Feedlot Industry Sector Profile
Revised Draft Report
December 30, 1998
C:\MYFOLD~1\FEEDLOTS\WAO-33.WPD
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Contents
Tables vii
Figures xiii
Acknowledgments xiv
1.0 Introduction 1-1
1.1 Background 1-1
1.2 Scope and Document Organization 1-5
1.3 References 1-6
2.0 Animal Waste Production in the United States 2-1
2.1 Introduction 2-1
2.2 Approach 2-1
2.3 Waste Generation 2-3
2.4 References 2-3
3.0 Dairy 3-1
3.1 Introduction 3-1
3.2 Housing 3-2
3.2.1 Replacement Housing 3-2
3.2.1.1 Calf Housing 3-3
3.2.1.2 Transition Housing 3-4
3.2.1.3 Heifer Housing 3-4
3.2.2 Housing During Periparturient (around calving) Period 3-4
3.2.3 Housing for Lactating Dairy Cows 3-4
3.2.4 Dry Cow Housing 3-5
3.3 Demographics 3-5
3.3.1 National Change 3-5
3.3.2 Geographic Distribution 3-6
3.4 Waste Management Systems 3-12
3.4.1 Nutritional Strategies 3-14
3.4.2 Waste Collection 3-14
3.4.3 Waste Storage 3-15
3.4.3.1 Solid and Semisolid Manure Storage Units 3-16
3.4.3.2 Liquid and Slurry Storage Units 3-16
3.4.4 Waste Disposal and Use 3-17
3.5 Example Systems 3-19
3.5.1 Connecticut 3-19
3.5.2 Idaho 3-19
3.5.3 Nebraska 3-19
3.5.4 Kansas 3-20
3.5.5 Oregon 3-20
3.5.6 California 3-21
3.5.7 Florida 3-21
3.5.8 Texas 3-22
3.6 Bibliography 3-22
iii
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Contents (continued)
4.0 Beef 4-1
4.1 Introduction 4-1
4.1.1 Cow-calf Operations 4-1
4.1.2 Finishing Operations 4-3
4.1.3 Housing and Related Facilities 4-4
4.2 National Distribution by Type and Size 4-5
4.3 Waste Management Technologies 4-13
4.3.1 Waste Reduction 4-13
4.3.2 Waste Collection, Storage, Treatment, and Use 4-14
4.3.2.1 Waste Collection 4-14
4.3.2.2 Waste Storage 4-15
4.3.2.3 Waste Treatment 4-16
4.3.2.4 Waste Use 4-17
4.4 Effectiveness of Waste Management Systems 4-18
4.5 Example Systems 4-18
4.5.1 Ohio 4-18
4.5.2 Southeast Region 4-19
4.5.3 Northeast Region 4-20
4.5.4 South-Central Region 4-20
4.5.5 Colorado 4-21
4.6 Bibliography 4-21
5.0 Sheep 5-1
5.1 Introduction 5-1
5.2 Demographics 5-2
5.2.1 National Change and Composition 5-2
5.2.2 Geographic Distribution 5-2
5.3 Waste Management Technologies 5-10
5.4 Bibliography 5-11
6.0 Horses 6-1
6.1 Introduction 6-1
6.2 Waste Management Technologies 6-2
6.2.1 Waste Collection and Handling 6-2
6.2.2 Waste Storage 6-3
6.2.3 Waste Treatment and Disposal 6-3
6.3 Bibliography 6-4
7.0 Ducks 7-1
7.1 Introduction 7-1
7.2 Type and Size 7-2
7.2.1 National Distribution 7-2
7.2.2 Regional Distribution 7-2
7.3 Waste Management Technologies 7-2
7.3.1 Nutritional Strategies 7-2
7.3.2 Waste Collection 7-2
7.3.3 Waste Storage, Handling, and Treatment 7-3
7.3.4 Waste Disposal and Use 7-4
7.3.5 Examples of Typical Systems 7-4
7.3.6 Component/Unit Cost 7-5
7.4 Bibliography 7-5
iv
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Contents (continued)
8.0 Goats 8-1
8.1 Introduction 8-1
8.2 Type and Size 8-1
8.2.1 National Distribution 8-1
8.2.2 Regional Distribution 8-3
8.3 Waste Management Technologies 8-3
8.3.1 Nutritional Strategies 8-3
8.3.2 Waste Collection 8-3
8.3.3 Waste Storage, Handling, and Treatment 8-4
8.3.4 Waste Disposal and Use 8-5
8.3.5 Examples of Typical Systems 8-6
8.3.6 Component/Unit Cost 8-7
8.4 Bibliography 8-7
9.0 Swine 9-1
9.1 Introduction 9-1
9.2 Demographics 9-5
9.2.1 National Change 9-5
9.2.2 Regional Distribution 9-6
9.3 Waste Management Systems 9-11
9.3.1 Nutritional Strategies 9-11
9.3.2 Waste Collection and Storage 9-13
9.3.3 Anaerobic Lagoon Treatment 9-15
9.4 Example Systems 9-16
9.4.1 Systems in Alaska, California, Hawaii, Idaho, Montana, Nevada, Oregon,
and Washington 9-16
9.4.2 Systems in Arkansas, Arizona, New Mexico, Oklahoma, Texas, and Utah 9-16
9.4.3 Systems in Connecticut, Delaware, Maryland, Massachusetts, Maine, New
Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont,
and West Virginia 9-17
9.4.4 Systems in Alabama, Florida, Georgia, Kentucky, Louisiana, Mississippi,
North Carolina, South Carolina, Tennessee, and Virginia 9-18
9.4.5 Systems in Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri,
Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin 9-19
9.5 Example System Costs 9-19
9.5.1 Water Flush/Lagoon/Spray Field System in the Southeast 9-20
9.5.2 Deep Pit Storage System in the Midwest 9-20
9.6 Bibliography 9-21
10.0 Poultry 10-1
10.1 Introduction 10-1
10.2 Demographics 10-1
10.2.1 Broilers 10-1
10.2.2 Turkeys 10-7
10.2.3 Layers 10-13
10.3 Waste Management Systems 10-20
10.3.1 Broilers 10-21
10.3.2 Turkeys 10-21
10.3.3 Layers 10-22
10.4. Economic Considerations 10-23
10.5 Bibliography 10-24
v
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Contents (continued)
11.0 Waste Management Systems Technologies and Practices 11-1
11.1 Introduction 11-1
11.2 Waste Generation 11-1
11.3 Waste Reduction Through Feeding Practices 11-6
11.4 Comparison of Common Waste Collection, Storage, and Treatment Practices 11-7
11.5 Solid-Liquid Separation 11-13
11.6 Anaerobic Digestion 11-14
11.7 Composting 11-16
11.8 OdorControl 11-18
11.9 Wetlands and Vegetative Filter Strips 11-20
11.10 Waste Disposal 11-21
11.11 Other Technologies 11-25
11.12 Other Effectiveness and Cost Information 11-26
11.13 Bibliography 11-28
Appendix A—Animal Waste Production Computation Method A-l
vi
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Tables
Table Page
1-1 Criteria from 40 CFR Part 122, Appendix B 1-1
1-2 Estimation of operations that might be CAFOs derived from data collected in the 1992
Census of Agriculture 1-3
1-3 Distribution of operations by animal category and size class derived from data collected
in the 1992 Census of Agriculture 1-4
2-1 Basic manure characteristics 2-2
2-2 Estimate of animal units and nutrients from manure by animal category and region 2-4
3-1 Distribution of calves, heifers, and mature cattle in a typical dairy herd 3-1
3-2 Percent of operations and cows on those operations that had outside area accessible on a
daily basis 3-2
3-3 Percent of U.S. dairy operations by herd size 3-5
3-4 Percent of U.S. milk cow inventory by herd size 3-6
3-5 Size distribution of all dairy operations derived from data collected in the 1992 Census
of Agriculture 3-6
3-6 Milk cows: number of operations by size group, selected states, and United States, 1997-1998 3-11
3-7 Milk cows: percent of inventory by size group, selected states, and United States, 1996-1997 3-12
3-8 Percent of operations by method of removing manure from cow housing areas 3-14
3-9 Flush parameters 3-15
3-9 Percent of operations by waste storage system 3-16
3-10 Percent of operations by waste disposal practice 3-18
4-1 Percent of beef cattle or weaned calves sold in 1996 by animal class and herd size 4-1
4-2 Operation average sale weight for beef cattle and weaned calves sold in 1996 by animal
class and herd size 4-2
4-3 Percent of cow-calf operations in 1996 by type of grazing used and herd size 4-2
4-4 Percent of cow-calf operations in 1996 by type of grazing used and state 4-2
4-5 Percent of cow-calf operations feeding hay, silage, supplements, or grain to the cow herd
during 1993 4-3
vii
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Tables (continued)
Table Page
4-6 Percent of cow-calf operations by water source and month 4-3
4-7 Percent of operations and beef cows where various methods were used to dispose of manure 4-3
4-8 Minimum lot space requirements for different lot slopes 4-5
4-9 Number of cattle and calves by class and year in the United States 4-6
4-10 Size distribution of all beef operations derived from data collected in the 1992 Census
of Agriculture 4-6
4-11 Number of operations by beef cow size group in selected states and United States,
1996-97 4-11
4-12 Cattle and calves: total number on feed by state, 1996-98 4-12
4-13 Comparative costs (1994 dollars) of composting methods 4-16
4-14 Fresh manure as excreted 4-18
4-15 Nitrogen losses with different handling techniques 4-18
4-16 Estimated N availability (%) as a function of soil properties, environment, and
application time and method for first year after application, assuming that 50%
of the applied N is organic N and 50% is inorganic N 4-19
5-1 Percent of operations and percent of sheep by primary flock type 5-1
5-2 Percent of operations and percent of sheep by primary breed category 5-2
5-3 Sheep inventory and lamb crop (January 1 sheep inventory) 5-3
5-4 Breeding sheep: survey percent of operations by size group in 1997 and 1998 5-3
5-5 Size distribution of all sheep operations derived from data collected in the 1992
Census of Agriculture 5-3
5-6 Number of breeding and market sheep and lambs by state during 1997 and 1998 5-4
5-7 Operations with sheep and lambs (1994-1997) 5-9
5-8 Fresh manure production and characteristics per 1,000 pounds of live animal weight
per day from ASAE Standard D384.1 DEC93 5-10
6-1 Horse "as excreted" manure characteristics 6-2
viii
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Tables (continued)
Table Page
6-2 Average manure application rates and area requirements for forages 6-4
7-1 Recommended indoor floor area per duck 7-1
7-2 Duck inventory and sales 7-2
7-3 1992 regional distribution of commercial ducks 7-2
7-4 Composition of fresh manure for a variety of animals 7-3
7-5 Approximate manure production by poultry 7-3
8-1 Goat inventory and sales 8-3
8-2 Regional distribution of angora goats 8-3
8-3 Regional distribution of dairy goats 8-3
8-4 Daily manure production by individual goats 8-4
8-5 Nutrient removal rates for various crops 8-5
8-6 Manure nutrient loss by days until worked into soil 8-6
9-1 Percent of swine operations that changed or developed waste management programs
due to environmental concerns or regulations affecting environmental quality 9-2
9-2 Waste management systems: types of flooring 9-2
9-3 Percent of swine operations using different waste storage systems 9-3
9-4 Swine operation waste disposal methods 9-3
9-5 Waste disposal methods of swine operations that do not separate solids and liquids 9-3
9-6 Waste disposal methods of swine operations that separate solids and liquids 9-3
9-7 Waste disposal methods used to dispose of liquid on owned or rented land (by percent) 9-4
9-8 Most frequently used waste management systems 9-4
9-9 Percent of operations using different waste management systems by production phase 9-4
9-10 Percent of producers using different methods of carcass disposal 9-4
9-11 Percent of U.S. hog operations by herd size, 1990-1995 9-5
ix
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Tables (continued)
Table Page
9-12 Percent of U.S. hog inventory by herd size, 1990-1997 9-5
9-13 Changes in the Number of U.S. swine operations (1990-1997) 9-5
9-14 Number of swine operations in selected states by size group 9-6
9-15 Theoretical model of the effects of reducing dietary protein and supplementing
with amino acids on nitrogen excretion by 200-lb finishing pig 9-11
9-16 Theoretical model of effects of dietary phosphorus level and phytase supplementation 9-12
9-17 Effect of microbial phytase on relative performance of pigs 9-13
9-18 Effect of microbial phytase on increase in phosphorus digestibility by age of pigs
and the recommended rates for inclusion of phytase in each phase 9-13
9-19 Distribution of pigs and predominant waste systems by farm size in Alaska, California,
Hawaii, Idaho, Montana, Nevada, Oregon, and Washington 9-17
9-20 Distribution of pigs and predominant waste systems by farm size in Arkansas, Arizona,
New Mexico, Oklahoma, Texas, and Utah 9-17
9-21 Distribution of pigs and predominant waste systems by farm size in Connecticut,
Delaware, Maryland, Massachusetts, Maine, New Hampshire, New Jersey, New
York, Pennsylvania, Rhode Island, Vermont, and West Virginia 9-18
9-22 Distribution of pigs and predominant waste systems by farm size in Alabama, Florida,
Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee,
and Virginia 9-19
9-23 Distribution of pigs and predominant waste systems by farm size in Illinois, Indiana,
Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South
Dakota, and Wisconsin 9-19
9-24 Sample costs and benefits of typical manure management systems 9-20
10-1 Broiler production in the United States, 1987-96 10-1
10-2 Broiler production by state, 1995 and 1996 10-2
10-3 Distribution of broiler operations derived from data collected in the 1992 Census
of Agriculture 10-7
10-4 Turkey production in the United States, 1987-96 10-7
10-5 Turkey production by state, 1996 10-8
x
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Tables (continued)
Table Page
10-6 Distribution of turkey operations derived from data collected in the 1992 Census
of Agriculture 10-13
10-7 Layer and pullet production in the United States, 1988-97 10-14
10-8 Distribution of layer operations derived from data collected in the 1992 Census of
Agriculture 10-14
10-9 Layer and pullet production by State, 1997 10-19
11-1 Annual volume and nutrient content of raw manure 11-2
11-2 Livestock waste characterization as excreted manure 11-3
11-3 Fresh manure production and characteristics per 1,000 lb live animal mass per day 11-4
11-4 Dairy waste characterization of milking center 11-5
11-5 Characterization of poultry waste litter 11-5
11-6 Approximate fertilizer nutrient values of animal manure as applied to land solid
handling systems 11-6
11-7 Approximate value (1994 dollars) of nutrients in animal manure as produced from a
solid manure handling system in Minnesota 11-6
11-8 Livestock waste characterization in anaerobic, aerobic, and runoff ponds 11-9
11-9 Percent of original nutrient content of manure retained by various management systems 11-10
11-10 Liquid manure nutrient concentrations in pit storage 11-10
11-11 Liquid manure nutrient concentrations in anaerobic lagoons 11-11
11-12 Nutrients produced for a dairy lagoon system 11-11
11-13 Nutrients produced for a dairy liquid manure tank system 11-11
11-14 Cost comparison (1994 dollars) of manure systems in Minnesota 11-12
11-15 Comparison of digester costs 11-16
11-16 Comparative costs of composting methods 11-19
11-17 Filter strip effectiveness 11-21
11-18 Estimated N availability, assuming 50 percent of N is organic N and 50 percent is
ammonium N 11-22
xi
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Tables (continued)
Table Page
11-19 Costs (1996 dollars) for vee and tanker spreaders 11-23
11-20 Costs of commercial application of liquid or slurry manure 11-24
11-21 Costs of commercial application of solid manure 11-24
11-22 Change in runoff concentrations with alum use, mg/L 11-25
11-23 Effectiveness and cost of waste treatment system components 11-27
11-24 Cost data (1993 dollars) for Pennsylvania state averages for manure management
practices 11-27
xii
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Figures
Figure Page
1-1 Regional grouping of states to facilitate data summaries presented in this report 1-5
3-1 Percent of operations by housing facilities for dairy heifers and adult cows 3-3
3-2 Number of milk cows per county 3-7
3-3 Number of operations per county with 500 or more milk cows 3-9
3-4 Basic components of solid and liquid manure systems for a dairy 3-13
4-1 Number of beef cows per county 4-7
4-2 Number of operations per county with 500 or more beef cows 4-9
4-3 Handling alternatives for beef cattle manure 4-13
5-1 Number of sheep and lambs per county 5-5
5-2 Number of operations per county with 1,000 or more sheep and lambs 5-7
6-1 Percent of operations and equids by primary function of operation 6-1
8-1 Loose housing for dairy goats 8-2
8-2 Individual stall housing for dairy goats 8-2
9-1 Number of hogs and pigs per county 9-7
9-2 Number of operations per county with 1,000 or more hogs and pigs 9-9
10-1 Number of broilers per county 10-3
10-2 Number of operations per county with 200,000 or more broilers sold 10-5
10-3 Number of turkeys per county 10-9
10-4 Number of operations per county with turkeys 10-11
10-5 Number of hens and pullets of laying age per county 10-15
10-6 Number of operations per county with 50,000 or more hens and pullets of laying age 10-17
11-1 Manure characteristics that influence management options 11-7
xiii
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Acknowledgments
This document was prepared by Tetra Tech, Inc. under EPA Contract 68-C7-0014, Work Assignment 1-33 by staff
located at the Fairfax, VA; Research Triangle Park, NC; and Las Cruces, NM offices. Chapter 9 and portions of
Chapter 10 are an abridged version of Chapters 1 through 8 of Draft Swine and Poultry Industry Characterization,
Waste Management Practices and Model Detailed Analysis of Predominantly Used Systems, prepared by North
Carolina State University on September 30, 1998, under EPA Contract 68-C7-0014, Work Assignment 1-27. SAIC
prepared selected summary tables that were derived from data collected in the 1992 Census of Agriculture under
EPA Contract 68-C4-0046, Work Assignment 4-24 based on technical direction from Maria Smith. EPA staff, Anna
Kinney and Paul Shriner, provided technical contributions to Chapter 11. Anna Kinney, Kurt Roos, and Warren
McFall provided comments on the draft document.
xiv
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1.0 Introduction
This study is part of a preliminary analysis of operations that breed and grow animals primarily for food stocks.
Typical and alternative waste management technologies and practices are described for a variety of animal sectors.
The information presented in this report is complemented by the technical information presented in the Draft of
Swine and Poultry Industry Characterization, Waste Management Practices and Model Detailed Analysis of
Predominantly Used Systems (NCSU, 1998).
1.1 Background
According to 40 CFR 122.23, an animal feeding operation (AFO) is a lot or facility (other than an aquatic animal
production facility) where the following conditions are met:
< Animals (other than aquatic animals) have been, are, or will be stabled or confined and fed or maintained for a
total of 45 days or more in any 12-month period.
< Crops, vegetation, forage growth, or post-harvest residues are not sustained in the normal growing season over
any portion of the lot or facility.
For purposes of 40 CFR 122.23, a concentrated animal feeding operation (CAFO) is an AFO that meets one of the
criteria summarized in Table 1-1 or has been designated on a case-by-case basis by the Environmental Protection
Agency (EPA). Criteria (a) in Table 1-1 are applicable for any facility while criteria (b) are applicable if one of the
following conditions is met: pollutants are discharged into navigable waters through a man-made ditch, flushing
system, or other similar man-made device; or pollutants are discharged directly into waters of the United States that
originate outside of and pass over, across, or through the facility or otherwise come into direct contact with the
animals confined in the operation; provided, however, that no AFO is a CAFO if the AFO discharges only in the
event of a 25-year, 24-hour storm event.
Table 1-1. Criteria from 40 CFR Part 122, Appendix B.
Animal Categories
Number of Animals
Criteria (a)
Criteria (b)
Slaughter and feeder cattle
1,000
300
Mature dairy cattle (whether milked or dry)
700
200
Swine each weighing over 25 kg (~55 pounds)
2,500
750
Horses
500
150
Sheep or lambs
10,000
3,000
Turkeys
55,000
16,500
Laying hens or broilers (continuous overflow watering)
100,000
30,000
Laying hens or broilers (liquid manure system)
30,000
9,000
Ducks
5,000
1,500
Animal units3
1,000
300
a According to 40 CFR Part 122, Appendix B, an animal unit is calculated as the number of slaughter and feeder cattle multiplied by 1.0, plus
the number of mature dairy cattle multiplied by 1.4, plus the number of swine weighing over 25 kg multiplied by 0.4, plus the number of sheep
multiplied by 0.1, plus the number of horses multiplied by 2.0.
1-1
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An assessment of the number of operations that might be CAFOs was made using the 1992 Census of Agriculture.1
Since the Census of Agriculture data are not directly comparable to the regulations summarized above, the
methodology included various scenarios to qualify the sensitivity of the assessment. The scenarios are as follows:
< Scenario 1: Broiler and layer operations with fewer than 30,000 animals for criteria (a) or fewer than 9,000
animals for criteria (b) were excluded.
< Scenario 2: Broiler and layer operations with fewer than 100,000 animals for criteria (a) or fewer than 30,000
animals for criteria (b) were excluded.
< Scenario 3: Broiler and layer operations with fewer than 100,000 animals for criteria (a) or fewer than 30,000
animals for criteria (b) were excluded; grazed sheep and horses were excluded.
< Scenario 4: Broiler and layer operations were excluded; grazed sheep and horses were excluded.
Complete details about the assessment methodology are provided in Sections A. 1 and A.2 of Appendix A. Table 1-2
presents the results of this assessment for 40 CFR Part 122. Scenario 4 excludes broilers and layers and has a
consideration for grazed sheep and horses, resulting in the lowest total number of operations (5,845) that might be a
CAFO based on criteria (a) from Table 1-1. Scenario 3 includes broiler and layer operations with more than 100,000
animals. Under this scenario, an additional 540 layer and 1,855 broiler operations might be a CAFO, for a total of
8,205 operations. In Scenario 2, grazing is not considered and the number of horse and sheep operations doubles.
Scenario 1 includes layer and broiler operations with more than 30,000 animals, resulting in increases to 1,731 and
12,785 operations, respectively.
A similar assessment was performed for 40 CFR Part 412. The results from this assessment are the same as those
presented in Table 1-2 for beef, dairy, swine, turkeys, layers, broilers, and ducks. In Scenarios 3 and 4, the number
of horse operations decreased by 3 from the results presented in Table 1-2. There was an 80 percent decrease in the
number of sheep operations for all scenarios using criteria (a); a 62 percent decrease in the number of sheep
operations using criteria (b), Scenarios 1 and 2; and a 71 percent decrease in the number of sheep operations using
criteria (b), Scenarios 3 and 4. There was also a decrease (between 5.6 and 7.9 percent) in mixed operations
depending on criteria and scenario. Overall, there was a decrease of between 0.5 and 1.2 percent of total operations.
More recently, USD A and EPA have considered normalizing operation sizes by computing the number of animal
units at a given operation using the same procedure. These computations are usually based on the number of animals
corresponding to 1000 pounds of live weight and are usually based on assumptions of average animal weight. The
results presented in Table 1-2 are based on EPA's current animal unit definition. For the remainder of this report;
however, the methodology developed by Lander et al. (1998) for dairy, beef, broilers, layers, and turkeys will be
adopted and extended to other animal categories. The Lander et al. (1998) procedure was selected because it had
already been designed to work with the Census of Agriculture data and included substantial work summarizing the
most current literature.2 The modified procedure is summarized in Section A.3 of Appendix A. Table 1-3 presents
the results of this assessment for the range of animal categories summarized in the 1992 Census of Agriculture
database.
1 The 1997 Census of Agriculture data were not available for preparation of this report.
2
Discussions with the senior author indicate that USDA is considering modifications to this methodology, but such modifications are
not available at this time.
1-2
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Table 1-2. Estimation of operations that might be CAFOs derived from data collected in the 1992 Census of Agriculture.
Part 122, criteria (a)
Part 122, criteria (b)
Scenario 1
Scenario 2
Scenario 3
Scenario 4
Scenario 1
Scenario 2
Scenario 3
Scenario 4
Animal
Category
Broiler and
layer
operations
with fewer
than 30,000
animals
excluded
Broiler and
layer
operations
with fewer
than 100,000
animals
excluded
Broiler and
layer
operations
with fewer
than 100,000
animals
excluded;
grazed sheep
and horses
excluded
Broiler and
layer
operations
excluded;
grazed sheep
and horses
excluded
Broiler and
layer
operations
with fewer
than 9,000
animals
excluded
Broiler and
layer
operations
with fewer
than 30,000
animals
excluded
Broiler and
layer
operations
with fewer
than 30,000
animals
excluded;
grazed sheep
and horses
excluded
Broiler and
layer
operations
excluded;
grazed sheep
and horses
excluded
Number of
Operations
Evaluated
Beef
967
967
967
967
2,678
2,678
2,678
2,678
147,201
Broilers
12,785
1,855
1,855
0
17,778
12,785
12,785
0
35,759
Dairy
952
952
952
952
5,565
5,565
5,565
5,565
155,339
Ducks
108
108
108
108
156
156
156
156
16,854
Horses
39
39
22
22
275
275
176
176
338,346
Layers
1,731
540
540
0
4,621
1,731
1,731
0
87,927
Sheep
114
114
53
53
674
674
197
197
83,650
Swine
2,879
2,879
2,879
2,879
19,613
19,613
19,613
19,613
202,315
Turkeys
689
689
689
689
2,402
2,402
2,402
2,402
15,591
Animal units3
221
221
215
215
1,739
1,739
1,694
1,694
735,812
Total"
20,339
8,289
8,205
5,845
54,614
46,922
46,301
32,047
791,627
a Uses EPA's current animal unit definition (see Table 1-1).
b Since an operation can be characterized as a CAFO for more than one animal category, the total number of operations might not equal the column total.
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Table 1-3. Distribution of operations by animal category and size class derived from data collected in the 1992 Census of Agriculture.
Animal Category
Size Class (Animal Units3)
1-25
25-100
100-300
300-500
500-1,000
1,000-5,000
5,000-10,000
10,000 or
More
Tot. Num.
of Oper.
Beef
612,458
314,125
77,239
12,982
7,749
3,665
256
240
1,028,714
Broilers
18,519
9,214
7,319
531
153
18
2
3
35,759
Dairy
41,111
73,864
33,901
3,579
1,764
1,090
25
5
155,339
Ducks
16,771
58
16
4
3
2
16,854
Geese
12,387
10
1
12,398
Goats
47,316
1,245
344
53
21
4
48,983
Horses
336,732
6,257
384
49
16
14
1
343,453
Layers
84,076
4,489
1,649
363
244
196
20
3
91,040
Mink
828
78
10
916
Mules, burros, donkeys
26,157
28
1
26,186
Other poultry
5,619
30
5
3
1
5,658
Pheasants
2,609
26
2
1
2,638
Pigeons
1,724
4
1,728
Quail
1,560
3
2
1,565
Rabbits
14,880
23
3
1
14,907
Sheep
81,869
3,179
924
152
93
36
1
1
86,255
Swine
138,860
49,661
14,499
1,840
963
328
21
12
206,184
Turkeys
12,251
274
1,128
810
766
344
10
8
15,591
a Lander et al. (1998) procedure for computing animal units was adopted and extended for this table and the remainder of this document.
-------
1.2
Scope and Document Organization
Data gathering for this report was limited to a literature search of readily available sources (including U.S.
Department of Agriculture documents, Census of Agriculture, U.S. EPA documents, academic documentation, and
trade literature) and information voluntarily submitted by stakeholders. Based on the data presented in Table 1-3,
geese, pigeons, pheasants, quail, other poultry, mules, burros, donkeys, rabbits, and mink are not considered in
detail. These sectors were excluded since each represents less than 2.5 percent of the total 1,061,056 operations that
raise livestock and more then 90 percent of the operations within each of these sectors is in the 1 to 25 animal unit
size class. Ducks also meet this criteria but were not excluded since ducks are included in the existing regulation. It
should also be noted that there was not much available data on the excluded sectors or any other sectors not
specifically considered.
The next chapter in this report is an assessment of the manure generation by animal operations across the United
States. Chapters 3 through 10 provide an animal sector profile summarizing key operational characteristics and
trends of dairy, beef, sheep, horses, goats, ducks, swine, and poultry (broilers, turkeys, and layers). Operational
characteristics include the type of animal handling, feeding, and waste handling practices and the advantages and
drawbacks associated with these practices. The information presented in Chapters 9 (swine) and 10 (poultry) were
abridged from the NCSU (1998) report that was prepared to support revisions to the pork and poultry subcategories
of the regulation (40 CFR 122.23 and 40 CFR Part 412). Chapter 11 presents a summary of waste treatment
technology effectiveness and cost data.
Throughout this report, data summaries have been prepared by region to better describe the geographic distribution
of the various animal sectors. For consistency, these regions correspond to those shown in Figure 1-1 although
future analyses might require different regional groupings for different animal sectors.
Figure 1-1. Regional grouping of states to facilitate data summaries presented in this report.
1-5
-------
1.3 References
Lander, C.H., D. Moffitt, and K. Alt. 1998. Nutrients Available from Livestock Manure Relative to Crop Growth
Requirements. U.S. Department of Agriculture, Natural Resources Conservation Service, Resource
Assessment and Strategic Planning Working Paper 98-1. . Accessed October 15, 1998.
NCSU. 1998. Draft of Swine and Poultry Industry Characterization, Waste Management Practices andModel
Detailed Analysis of Predominantly Used Systems. North Carolina State University, Raleigh, North
Carolina. September.
1-6
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2.0 Animal Waste Production in the United States
2.1 Introduction
This chapter describes the procedures and results associated with estimating animal waste production in the United
States. It is based on the methodology developed by Lander et al. (1998) and the 1992 Census of Agriculture data
(Geographic Area Series IB, U.S. Summary and County Level Data).
2.2 Approach
The Lander et al. (1998) approach for computing animal units, manure production, and nutrient availability was
adopted for beef, dairy, swine, broilers, layers, and turkeys. The basic methodology was extended for other animal
sectors through additional literature searches and assessment. The top portion of Table 2-1 summarizes the work
from Lander et al. (1998); the bottom portion of the table documents the sources and assumptions used to extend
their procedure to additional animal sectors.
For animals taken from birth to market weight in the same operation, a simple average weight between birth and
market weight was used. These values were then converted into the number of animals per animal unit (Table 2-1,
third column). Production length was set to 365 days per year, which tends to overestimate manure production for
operations that have multiple cycles per year. In cases such as broilers, the amount of down time is not controlled by
the individual producer. Manure generation and nutrient content as excreted were compiled from the Livestock
Waste Facilities Handbook (Midwest Plan Service, 1985), Agricultural Waste Management Field Handbook
(USDA-NRCS, 1992), Livestock Manure Characterization Values From the North Carolina Database (NCSU,
1990), and Manure Production and Characteristics (ASAE Standard D384.1). Local information generally proved
to be local adaptations of nationally available information. According to Lander et al. (1998)
The categories of nitrogen, phosphorus, and potassium content (after losses) in [Table 2-1] were
added to provide a mechanism for estimating the amount of nutrients that would be present in land
applied manure and effluent. There is no national or even regional perspective on what these
values should be. The estimates shown are based on a three part assumption:
< Nitrogen losses will exceed (greatly exceed) those of phosphorus and potassium primarily due
to volatilization of nitrogen compounds.
< As the quality (from an automation view) and numbers of manure management systems
improve, the losses of nutrients, particularly nitrogen, may increase. In other words, as the
manure management system becomes more automated, nitrogen losses through volatilization
also increase.
< Phosphorus and potassium amounts are present within the bottom sludge of lagoons and
ponds, and even though the sludge is not removed on a regular basis, the phosphorus and
potassium content must be considered in an application strategy; i.e., effluent composition
may not reflect actual nitrogen, phosphorus and potassium in the lagoon or holding pond.
Numerous individuals in USD A, at universities, and part of the industry groups were consulted to
arrive at the national values for after losses. The discussions focused on the types of manure
systems typically used by the industry in different parts of the country, the losses typically
associated with these systems ..., and the portion of the nation's livestock raised in different parts of
the country. The values shown in [Table 2-1] are estimates based on all these assumptions and
considerations.
2-1
-------
Table 2-1. Basic manure characteristics.
Animal Category
Census
Variable
Symbol
Animal
/AU
Annual
Manure
Production
Factors
(Tons/
AU-yr)
Manure Nutrient Content Factors (lbs/ton)
Produc.
Cycles
(#/year)
Nitrogen
Phosphorus
Potassium
as
excreted
after
losses
as
excreted
after
losses
as
excreted
after
losses
Beef cows a
K804
1
11.50
10.95
3.3
3.79
3.23
8.25
7.44
1
Milk cows a
K805
0.74
15.24
10.69
4.3
1.92
1.65
6.70
6.04
1
Calves a
K804 or
K805
4
Heifers and heifer calves a
K806
1.82
12.05
6.06
1.82
1.30
1.10
5.03
4.53
1
Steers, steer calves, bulls, and bull
calves a
K807
1.64
10.59
10.98
3.3
3.37
2.86
7.87
7.08
1
Fattened cattle sold a
K812
1.14
10.59
10.98
4.39
3.37
2.86
7.87
7.08
2.5
Breeding hogs/pigs a
K816
2.67
6.11
13.26
3.32
4.28
3.62
7.85
7.04
1
Other hog/piga
K817
9.09
14.69
11.30
2.82
3.29
2.80
7.95
7.16
2
Hens/pullets laying age a
K892
250
11.45
26.93
18.46
9.98
8.50
10.44
9.40
1
Pullets>3 months, not laying a
K894
250
8.32
27.20
13.6
10.53
8.95
11.41
10.27
2
Pullets<3 months a
K896
455
8.32
27.20
13.6
10.53
8.95
11.41
10.27
2
Broilera
K898
455
14.97
26.83
16.1
7.80
6.61
10.49
9.48
6
Turkeys for slaughtera
K900
67
8.18
30.36
16.18
11.83
10.06
11.61
10.44
2
Turkey hens for breed a
K902
50
9.12
22.41
11.2
13.21
11.23
7.60
6.84
1
Horse
K830
lb
9.31 b
11.76 b
3.53 n
2.78 b
2.37 p
9.80 b
8.82 '
1
Donkeys/mules/burros
K833
1.7°
1
Sheep
K824
16.7 b
7.30 b
21.00 b
6.30°
4.35 b
3.70 p
16.00 b
14.40 '
1.5
Milk goats
K843
7.6 w
7.48 b
21.95 b
6.59°
5.37b
4.56 p
15.12b
13.61 '
1
Angora goats
K847
10 e
7.48 m
21.95 m
6.59°
5.37 m
4.56 p
15.12 m
13.61 '
1
Mink
K836
200 f
0.20
2 1
Rabbit
K854
1548
2.5 1
Duck
K904
244 b-h
20.08 b
27.27 b
16.36°
9.82 b
8.35 p
12.91 b
11.62 '
5 1
Geese
K906
101h
2 1
Pigeons
K908
435 1
3 1
Pheasants
K910
357j
4 1
Quail
K912
4760 k
5 1
a Lander et al. (1998)
b ASAE Standard (1998) D384.1
c L. Patton, personal communication 7/13/98
d http: 11 us link. net/~act/bmf/history. html
e http://members.aol.com/melodiehll/goats.html
f http://agri.gov.ns. ca/rs/greenplan/waste/061 .html
8 http://www.rabbit.org/faq/faq.txt
h http://eru.usask.ca/saf_corp/livestock/poultry/ducks_and_geese.html
1 http://www.geocities.com/Athens/Acropolis/6450/ BASICPIGEONH
j http://ndsuext.nodak.edu/extpubs/alt-ag/pheasan.htm
k http://pages.prodigy.net/nightfalcon/bobwhite.htm
1 Estimated based on ratio of animals sold to inventory from 1992
Census of Agriculture
m Estimated from milk goats
n Estimated as 30 percent of nitrogen excreted
0 Estimated as 60 percent of nitrogen excreted
p Estimated as 85 percent of phosphorus excreted
>.html q Estimated as 90 percent of potassium excreted
To calculate the quantities of nutrients available from animal manure, it was necessary to estimate
the quantities of recoverable manure for each of the animal categories studied ... In application, the
recoverable manure factors are multiplied times the tons of manure per animal unit or by the total
tons of manure produced by the entire population of an animal category to arrive at the value of
recoverable manure. Nutrient values per ton [of recoverable manure] remain the same [as excreted
manure] based on the assumption that the decrease in nutrients ... mirror[s] the reduction in the
solids content [from excreted to] recoverable manure. This assumption is environmentally
conservative and, for phosphorus and potassium, is relatively sound. For nitrogen, however, the
assumption has some problems. Nitrogen, being relatively volatile in some forms, has a tendency
to decrease rapidly as the manure is left unrecovered. Unfortunately, there is relatively little
information to relate recoverable manure and recoverable nitrogen. It could vary both by animal
2-2
-------
type and management style. The best estimate of manure nutrient content for land application
comes from considering both recoverable manure and after losses together, i.e., neither taken
separately tells the complete story.
Based on the typical nutrient losses developed by Lander et al. (1998), similar values were developed for the
additional animal categories. For this report, manure as excreted and recoverable manure after losses are evaluated.
The equations used in this analysis are summarized in Appendix A, Exhibits A-l and A-2.
2.3 Waste Generation
Using state summary-level data from the 1992 Census of Agriculture, the number of animal units and amount of
nutrients as excreted and recoverable after losses were estimated. State- and region-level results are presented in
Appendix A, Tables A-7 and A-8. Table 2-2 presents a summary of this information.
Beef accounts for 62.6 percent (51,051,678 animal units) of the total number of farm-domesticated animal units.
Dairy and swine follow with 18.1 and 9.6 percent of the total animal units, respectively. Layers, broilers, turkeys,
horses, sheep, and goats account for the remaining 9.7 percent of the animal units.
Beef accounts for more than one-half (53 percent) of the nitrogen as excreted, but only 18.5 percent of the
recoverable nitrogen after losses. Dairy accounts for nearly one-fifth (19.9 percent) of the excreted nitrogen, but
30.4 percent of the recoverable nitrogen after losses. Swine account for less than one-tenth (9.5 percent and 8.9
percent) of the excreted nitrogen and recoverable nitrogen after losses. Broilers, layers, and turkeys account for 14.1
and 37.2 percent of the excreted nitrogen and recoverable nitrogen after losses, respectively.
Beef accounts for more than one-half (58.8 percent) of the excreted phosphorus and about one-fourth (23.7 percent)
of the recoverable phosphorus after losses. Dairy account for 12.5 percent of the excreted phosphorus and 21.9
percent of the recoverable phosphorus after losses. Swine account for 9.6 percent of the excreted phosphorus and
16.2 percent of the recoverable phosphorus after losses. Broilers, layers, and turkeys account for 16.5 and 32.5
percent of the excreted phosphorus and recoverable phosphorus after losses, respectively.
Horses, sheep, goats, and ducks account for less than 3.3 and 2.5 percent of the nitrogen and phosphorus as excreted,
respectively. Assuming 100 percent recovery (a high estimate), horses, sheep, goats, and ducks account for 4.8 and
5.7 of the nitrogen and phosphorus after losses, respectively.
2.4 References
Lander, C.H., D. Moffitt, and K. Alt. 1998. Nutrients Available from Livestock Manure Relative to Crop Growth
Requirements. U.S. Department of Agriculture, Natural Resources Conservation Service, Resource
Assessment and Strategic Planning Working Paper 98-1. . Accessed October 15, 1998.
2-3
-------
Table 2-2. Estimate of animal units and nutrients from manure by animal category and region.
Animal
Category
Animal Units
Nitrogen as
Excreted
Recoverable
Nitrogen after
Losses
Phosphorus as
Excreted
Recoverable
Phosphorus after
Losses
Potassium as
Excreted
Recoverable
Potassium after
Losses
AU
Percent
Tons
Percent
Tons
Percent
Tons
Percent
Tons
Percent
Tons
Percent
Tons
Percent
Beef
51,051,678
62.6
2,991,126
53.0
213,334
18.5
977,468
58.8
150,560
23.7
2,244,666
59.3
370,701
24.6
Broilers
1,970,429
2.4
395,707
7.0
229,673
19.9
115,040
6.9
94,294
14.8
154,713
4.1
135,236
9.0
Dairy
14,756,164
18.1
1,124,909
19.9
350,093
30.4
207,227
12.5
139,083
21.9
718,387
19.0
504,932
33.5
Ducks'
15,059
0.02
4,123
0.07
2,473
0.2
1,485
0.09
1,262
0.2
1,952
0.05
1,757
0.1
Goats'
194,064
0.2
15,931
0.3
4,783
0.4
3,898
0.2
3,310
0.5
10,974
0.3
9,878
0.7
Horses3
2,049,522
2.5
112,197
2.0
33,678
2.9
26,523
1.6
22,611
3.6
93,497
2.5
84,147
5.6
Layers
1,246,034
1.5
182,971
3.2
114,557
9.9
68,224
4.1
55,098
8.7
71,734
1.9
61,257
4.1
Sheep1'
673,154
0.8
51,597
0.9
15,479
1.3
10,688
0.6
9,091
1.4
39,312
1.0
35,381
2.3
Swine
7,814,778
9.6
538,467
9.5
101,952
8.9
160,096
9.6
103,160
16.2
367,121
9.7
250,560
16.6
Turkeys
1,836,468
2.3
221,911
3.9
85,650
7.4
92,161
5.5
57,437
9.0
83,628
2.2
54,886
3.6
Total
81,607,349
5,638,938
1,151,673
1,662,809
635,908
3,785,985
1,508,736
Region
Animal Units
Nitrogen as
Excreted
Recoverable
Nitrogen after
Losses3
Phosphorus as
Excreted
Recoverable
Phosphorus after
Losses3
Potassium as
Excreted
Recoverable
Potassium after
Losses3
AU
Percent
Tons
Percent
Tons
Percent
Tons
Percent
Tons
Percent
Tons
Percent
Tons
Percent
Mountain
9,902,263
12.1
606,993
10.8
72,458
6.3
184,408
11.1
42,036
6.6
445,571
11.8
121,245
8.0
North-Central
32,433,500
39.7
2,159,519
38.3
430,893
37.4
632,351
38.0
268,642
42.2
1,479,577
39.1
681,762
45.2
Northeast
4,544,869
5.6
374,712
6.6
127,936
11.1
91,808
5.5
58,479
9.2
225,245
5.9
147,498
9.8
South-Central
15,300,869
18.7
1,023,170
18.1
169,596
14.7
319,362
19.2
91,677
14.4
703,524
18.6
197,080
13.1
Southeast
13,216,785
16.2
1,027,891
18.2
246,784
21.4
316,102
19.0
126,316
19.9
639,576
16.9
224,879
14.9
West
6,056,642
7.4
437,060
7.8
102,857
8.9
115,843
7.0
48,103
7.6
285,571
7.5
134,557
8.9
Other
152,421
0.2
9,593
0.2
1,151
0.1
2,935
0.2
654
0.1
6,920
0.2
1,714
0.11
Total
81,607,349
5,638,938
1,151,673
1,662,809
635,908
3,785,985
1,508,736
a Assumes all manure from horses, sheep, goats, and ducks is recoverable.
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3.0 Dairy
3.1 Introduction
The care and management of the dairy cow depends on the animal's age, lactation and pregnancy status, and health,
as well as the location, facilities, and surrounding environment. Nearly all dairy operations (93 percent) use holstein
cows as the primary animal breed. Dairy operations that primarily use Jersey and Guernsey cows account for 4.1 and
1.7 percent of the dairies. Ayrshire, Brown Swiss, and other breeds account for the remaining 1.2 percent of dairy
operations (APHIS, 1996a). Table 3-1 shows the distribution of calves, heifers, and mature cattle in a typical dairy
herd.
Table 3-1. Distribution of calves, heifers, and mature cattle in a typical dairy herd.
Herd size (total mature cows)
75
100
250
400
Calves and heifers (total)
75
100
250
400
0-2 months, 150 lb
6
8
20
32
3-5 months, 250 lb
9
12
30
48
6-8 months, 400 lb
9
12
30
48
9-12 months, 600 lb
14
18
45
72
13-15 months, 800 lb
9
12
30
48
16-24 months, 1,050 lb
28
38
95
152
Dry cows (total)
13
17
43
68
Transition (first 4-14 days)
0-4
1-5
4-9
5-16
Next 40 days (divide in 2 groups)
8-9
11-12
28-30
45-48
Close-up (2-3 weeksprepartum)
2-5
3-6
8-15
16-24
Maternity (individual pens)
3-5
4-6
10-16
16-24
Fresh cows (0-7 days postpartum)
1-3
1-4
3-10
4-12
Two-year-olds (305 days lactation)
18-24
26-30
65-75
104-120
Three years and older (305 days lactation)
44
58
145
232
High producers (< 120 days)
15-18
20-24
50-60
80-96
Medium producers
12-15
16-20
40-50
60-72
Low producers
12-15
16-20
40-50
60-72
Sick cows
0-4
0-5
0-13
0-20
Source: Adapted from MWPS (1997). Numbers assume uniform calving year-around, 12-month calving interval,
first calving at 24 months of age, all males sold at birth, a 30% culling rate, 0% mortality, and a stable herd size.
After calving, a dairy cow is normally milked two or three times a day for 10 to 12 months. Once milking is stopped,
the cow is called a "dry" cow. This dry period, which usually begins 40 to 70 days (with an average of 61.7 days)
prior to the next calving, allows for the regeneration of milk secretory tissue in the udder. On average, dairy cows
have an average calving interval of 13 months, with the first calving at 25.5 months.
Most cows have access to outside areas. Table 3-2 summarizes the percentage of lactating and dry cows that have
access to outside areas on a daily basis during the summer and winter months.
Each year, up to one-third of the lactating dairy cattle are culled from the herd. The average percentage of cows
culled from the herd in 1995 (as a percent of January 1, 1996, dairy cow inventory) is 24 percent. The leading
reasons for culling include reproductive problems, udder or mastitis problems, poor production, or lameness/injury.
Operations that use milk production as a criterion for culling use an average of 33.4 pounds of milk per cow per day
to determine when to cull non-pregnant dairy cows. Most culls (95.5 percent) go to slaughter, but some (4.5 percent)
are purchased at auctions and relocated to other farms (APHIS, 1996a).
3-1
-------
Table 3-2. Percent of operations and cows on those operations that
had outside area accessible on a daily basis.
Type of Area
Lactating Cows
Dry Cows
Summer
Winter
Summer
Winter
Percent
Oper.
Percent
Cows
Percent
Oper.
Percent
Cows
Percent
Oper.
Percent
Cows
Percent
Oper.
Percent
Cows
Both pasture
and dry lot
41.8
31.7
11.4
10.8
38.4
30.7
11.4
12.5
Pasture only
27.7
18.5
5.5
4.5
39.9
34.6
9.5
11.0
Dry lot only
21.6
37.5
57.5
59.6
18.4
32.0
56.7
56.3
Neither
pasture nor
dry lot
8.9
12.3
25.6
25.1
3.3
2.7
22.4
20.2
Source: APHIS, 1996c.
Many dairy operations use artificial insemination as the primary means for breeding cows. In fact, 45.4 percent of
operations do not keep bulls in their inventory (APHIS, 1996a). Some dairies use bulls to breed cows that had
difficulty conceiving through artificial insemination or aborted early in gestation. These bulls, referred to as "clean-
up" bulls, are housed with cows in group corrals. Clean-up bulls are usually purchased from registered breeders to
provide superior genetics for the herd. Sometimes semen is collected from the clean-up bulls and distributed to other
dairies for artificial insemination.
Heifer calves are usually raised as replacements for lactating cows. Forty-five percent of heifer calves are separated
from the mother immediately (no nursing), 27.4 percent are separated within 12 hours, 18.7 percent are separated
within 12 to 24 hours, and 8.9 percent are separated after 24 hours. Weaning involves the transition from a milk-
based diet to a forage or concentrate. On average weaning occurs at 8.7 weeks, with 94.2 percent of heifer calves
weaned between 4 and 12 weeks (APHIS, 1996a). Usually, a healthy calf can be weaned successfully once it is
eating at least 1.5 pounds of calf starter (dry feed). Nationally, 1.7 percent (7.8 percent in the West) of farmers have
someone else raise their heifers on a contract basis (APHIS, 1993). Some bull calves are raised for veal or beef or
are terminated soon after birth. The proportion of bull calves raised for veal or beef is geographically variable.
From birth to weaning is the time of the greatest mortality and morbidity. About 10.8 percent of heifer calves die
before weaning, primarily due to scours, diarrhea, digestive problems, or respiratory problems. Approximately 2.4
percent of weaned heifers die before first calving, and 3.8 percent of dairy cows die each year (APHIS, 1996a).
3.2 Housing
Most dairy operations provide separate housing for different groups of animals based on age (calf versus cow) and
milking status (lactating versus dry). Figure 3-1 summarizes the percent of operations by housing facilities for dairy
heifers and adult cows. Housing can also be characterized as cold versus warm housing. Cold housing is
uninsulated, with natural ventilation designed as an integral part of the building. Indoor temperatures are closely
related to outside temperatures. Cold housing systems are less expensive to build and are easily ventilated, allowing
better disease control. During cold weather cold housing can make manure handling more difficult, as well as
increasing feed consumption to maintain body heat. Warm housing, or environmentally controlled housing, tends to
be less desirable since it is typically more expensive to construct and requires increased management.
3.2.1 Replacement Housing
Replacement housing can be grouped into the following categories: calf housing (0-2 months), transition housing (3-
5 months), and heifer housing (6-24 months).
3-2
-------
Hutch
Individual Animal Area
Multiple Animal Area
Tie Stall or Stanchion
Dry Lot
Pasture
Individual Animal
Area
Multiple Animal Area
Tie Stall or Stanchion
Dry Lot
Pasture
20 40 60
Maternity
Figure 3-1. Percent of operations by housing facilities for dairy heifers and
adult cows (Source: APHIS, 1996a).
3.2.1.1 Calf Housing
As mentioned earlier, the period from birth to weaning is the time of greatest mortality and morbidity, therefore,
special care is taken to minimize enviromnental stress by ensuring that the housing provides protection from heat,
cold, wind, and rain. Adequate space, comfort, and proper ventilation are also important when designing calf
housing. Facilities are designed for complete cleaning and disinfecting on a regular basis to reduce the number of
pathogens. The types of housing that can be used for calves include individual pens, hutches, and closed housing
(Stull, 1996).
Individual pens. Individual pens separate calves and reduce the spread of communicable diseases. Individual pens
also make it easier to observe changes in behavior, feed consumption, and waste production, which can indicate
sickness. In cold housing systems, pens are typically 4 by 7 feet and removable. A cover on the back half of the pen
may be added to give the calf additional protection in drafty locations. These pens are usually placed on crushed
rock or concrete as a base for bedding. In warm housing systems, it is possible to use 2 by 4 foot expanded metal or
slatted wood elevated pens. However, to avoid hock, leg, and joint problems sometimes associated with the metal
pens, expanded metal is coated with plastic. Because these pens provide little shelter from drafts and cold in the
winter, calves may suffer from cold stress, making it advisable to avoid individual pens for housing calves in colder
climates. Pneumonia may also be associated with the elevated pens that are placed over flush systems for cleaning.
These problems can be minimized if the pen size is doubled and a bedding box filled with straw or other comfortable
materials is added.
Hutches. Most individual outside hutches are approximately 4 by 8 by 4 feet and made out of wood. One end of the
hutch is left open, and wire fence is provided to allow the calf to move outside. Hutches are more labor-intensive
than elevated metal pens, but they allow for complete separation of unweaned calves and better insulation from
drafts. Hutches are easy to move and can be modified to account for temperature, sunlight, predominating winds,
and direction of inclement weather. This mobility also allows for easier cleaning. Fiberglass or polyethylene hutches
are easier to sanitize than wooden hutches or metal pens.
Closed housing. An enclosed barn containing individual pens constitutes "closed housing." Problems of
accumulating moisture and manure gases (methane, carbon dioxide, hydrogen sulfide, and ammonia) increase calves'
susceptibility to respiratory diseases, making it critical for closed housing to have adequate ventilation.
Environmentally controlled closed housing is expensive to construct and operate, and it requires more management
than the other types of calf housing.
3-3
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3.2.1.2 Transition Housing
As calves age, group size may be increased. After about 150 days of age, calves may be placed on pasture or housed
in groups of up to 100 to 200, sorted into uniform groups with individual calves having no more than about 10
percent weight variation from the mean of the group. Typical housing includes calf shelters or super hutches,
transition barn, and calf barn.
Calf shelter or super hutches. These portable pens provide a feeder, water trough, and shelter for up to six calves,
usually providing calves with 25 to 30 square feet each (Morrill et al., 1991 and Stull, 1996). Super hutches can be
moved in a field or pasture when necessary to provide a clean surface for the calves.
Transition barn. A transition barn provides a series of pens (typically 10 by 24 feet) for calves up to 6 months old.
Capacity is slightly higher if the entire pen is bedded (eight versus six animals). Transition barns usually have a
single sloped roof and are open to the south or east to take advantage of sunlight. The back and end walls can be
removed in the summer for natural ventilation.
Calf barn. A calf barn combines individual pens and transition group pens for calves in one building design. Pens
are designed for easy dismantling and manure removal.
3.2.1.3 Heifer Housing
The most common types of housing for heifers after 6 months of age are freestall and bedded pack housing systems.
In freestalls, young heifers are grouped in stalls that are sized to be compatible with the age or size of the heifer.
Freestall housing requires less bedding than bedded pack housing, but more frequent manure removal from alleys.
Bedded pack housing is often used with an outside feeding area. It is sized to allow for installation of a scrape alley
and freestalls at a later date. The bedded area is roofed to provide a warm, draft-free resting surface and includes
substantial amounts of bedding to keep animals clean and dry. Manure is removed as a solid two to four times a
year.
3.2.2 Housing During Periparturient (around calving) Period
Sod pastures are often used for calving during the summer, but might become too muddy during the winter in some
climates. Maternity and calving pens may also be used. In those operations where special housing is provided, cows
are moved to a "close-up" pen for easier observation (usually 2 weeks before parturition). When parturition is very
near, cows are moved to a maternity area for calving (Stull, 1996).
Close-up cow pens. Cow density in close-up cow pens is about one-half the density in lactating cow pens to allow
the calving cows some space to segregate themselves from other cows.
Maternity area. A pasture can be used for the maternity area; small individual pens are also suitable. Pens are
usually designed to allow at least 100 square feet per cow and maintain a well-ventilated but not drafty environment.
3.2.3 Housing for Lactating Dairy Cows
Nearly 70 (69.5) percent of operations use tie stall or stanchion type milking parlors. These account for 43.9 percent
of the cows in the United States. Milking parlors are used in 28.8 percent of the dairy operations and account for
54.9 percent of the cows milked in the United States (APHIS, 1996a). Methods to house lactating cows include
freestall barns and loose housing such as barns, corrals, or shades. The predominant flooring type for lactating cows
is concrete (83.2 percent of cows), followed by dirt (9.6 percent), pasture (4.6 percent), and concrete slats (1.6
percent). About two-thirds (66.9 percent) of operations use straw and/or hay for bedding, followed by wood
products (27.9 percent), rubber mats (27 percent), corn cobs or stalks (12.8 percent), sand (11.2 percent), and
shredded newspaper (6.7 percent) (APHIS, 1996c). Composted manure, rubber tires, and mattresses were also
identified as bedding.
3-4
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Freestalls. Freestalls are individual cow bedding areas where comfort and sanitation are aided through partitions
separating the cows. One stall is provided for each lactating cow, and in some cases more stalls may be added to
accommodate herd growth and provide an escape area for subordinate animals to move away from more aggressive
members of the herd.
Loose Housing. Loose housing units, such as barns, shades, and corrals, provide the dairy cow with thermal and
physical comfort and minimize disease. Because overcrowding tends to intensify unfavorable conditions like excess
moisture, manure accumulation, and reduced ventilation, which can lead to cow health problems such as mastitis and
pneumonia, animal spacing is important under loose housing conditions. The recommended loafing space for each
cow is 40 to 50 square feet of roofed area, in semi-arid conditions. In unpaved earthen exercise corrals, the
recommended space for a group of 100 cows is 500 to 600 square feet per animal. When corrals are paved, space can
be reduced to 100 square feet per animal. Alternatively, in cooler climates only 20 to 30 square feet of roofed area
per animal is necessary for small breeds and 30 to 40 square feet for larger breeds (Stull, 1996). Surfaces in loose
housing should contain scarified concrete areas that are 15 to 20 feet wide around water troughs, feed bunks, and
entrances to give cows ample footing in these areas. The hard surfaces should also have a 4 percent slope for proper
drainage. Dirt lots should slope at 4 percent or more, depending on the soil type and rainfall (Stull, 1996). Mud
problems can be reduced in these areas with proper drainage and berming to control rainwater.
3.2.4 Dry Cow Housing
Dry cows are usually housed in groups for about 40 days. If using earthen corrals in semi-arid conditions, 500 to 600
square feet of loafing area and 40 to 50 square feet of shade are provided per cow. If using freestalls, one stall or 25
square feet is allocated per cow. Exercise pens are designed for 100 to 200 square feet per cow.
3.3 Demographics
3.3.1 National Change
The number of milk cows in the United States has continuously decreased since the peak of 24.1 million milk cows
in 1940. According to the National Agricultural Statistics Service (NASS), there were approximately 9.7 million and
9.4 million milk cows in 1991 and 1996, respectively. The number of dairy operations has also decreased from
180,640 in 1991 to 140,090 in 1996 (APHIS, 1996b). Tables 3-3 and 3-4 present the percentage of U.S. dairy
operations and milk cow inventory by size class from 1991 through 1995. The trend since 1991 has been that the
proportion of smaller herds (1 to 49 head) has steadily decreased while the proportion of larger herds (50 or more
head) has steadily increased.
Table 3-3. Percent of U.S. dairy operations by herd size.
Year
1-29 Head
30-49 Head
50-99 Head
100-199
Head
200 or More
Head
1991
39.8
22.8
25.9
11.5a
a
1992
38.9
22.1
26.0
13.0a
a
1993
37.2
22.2
26.9
9.3
4.4
1994
35.8
22.0
27.7
9.9
4.6
1995
34.4
22.2
27.9
10.5
5.0
' The 100-199 size group includes 200 or more head.
Source: NASS data as presented by APHIS (1996b).
3-5
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Table 3-4. Percent of U.S. milk cow inventory by herd size.
Year
1-29 Head
30-49 Head
50-99 Head
100-199
Head
200 or More
Head
1991
6.3
16.6
31.7
45.4a
a
1992
5.5
15.2
30.0
49.3a
a
1993
5.0
14.8
29.2
19.2
31.8
1994
4.6
14.0
28.7
19.3
33.4
1995
4.0
13.0
28.0
20.0
35.0
a The 100-199 size group includes 200 or more head.
Source: NASS data as presented by APHIS (1996b).
3.3.2 Geographic Distribution
Dairy cattle are distributed in several regions in the United States. Table 3-5 summarizes the number of operations
in each region by operation size class computed from the 1992 Census of Agriculture. In 1992, more than one-half
of all operations were located in the North-Central Region, although more than one-half of the operations with 500
or more animal units were located in the West Region. Figure 3-2 presents a geographic distribution of the number
of milk cows per county, and Figure 3-3 presents the geographic distribution of operations with 500 or more milk
cows.
Table 3-5. Size distribution of all dairy operations derived from
data collected in the 1992 Census of Agriculture.
Operations Categorized by Size
Class (animal units3)
500-
1,000-
5,000-
10,000 or
Location
1-25
25-100
100-300
300-500
1,000
5,000
10,000
More
Total
Northeast
5,349
15,925
8,623
642
198
40
0
0
30,777
(13%)
(21.6%)
(25.4%)
(17.9%)
(11.2%)
(3.7%)
(0.0%)
(0.0%)
(19.8%)
Southeast
7,637
4,595
3,872
599
196
93
2
2
16,996
(18.6%)
(6.2%)
(11.4%)
(16.7%)
(11.1%)
(8.5%)
(8%)
(40%)
(10.9%)
North-Central
15,816
49,947
16,611
772
149
16
0
0
83,311
(38.5%)
(67.6%)
(49%)
(21.6%)
(8.4%)
(1.5%)
(0.0%)
(0.0%)
(53.6%)
South-Central
5,729
1,881
2,307
483
170
71
3
1
10,645
(13.9%)
(2.5%)
(6.8%)
(13.5%)
(9.6%)
(6.5%)
(12%)
(20%)
(6.9%)
Mountain
4,129
1,027
1,179
288
215
165
8
1
7,012
(10%)
(1.4%)
(3.5%)
(8%)
(12.2%)
(15.1%)
(32%)
(20%)
(4.5%)
West
2,388
482
1,304
791
829
700
12
1
6,507
(5.8%)
(0.7%)
(3.8%)
(22.1%)
(47%)
(64.2%)
(48%)
(20%)
(4.2%)
Other
63
7
5
4
7
5
0
0
91
(0.2%)
(0.0%)
(0.0%)
(0.1%)
(0.4%)
(0.5%)
(0.0%)
(0.0%)
(0.1%)
United States
41.111
73,864
33,901
3,579
1,764
1,090
25
5
155,339
a The procedure for estimating animal units was adopted from Lander et al. (1998).
One of the geographical shifts since 1992 has been the increased number of milk cows that have calved in many of
the western and mountain states, with the largest increase being 88.1 percent in New Mexico. On the other hand, the
largest decreases in the number of milk cows that have calved have occurred in the southeastern states, with the
largest decrease (besides Wyoming, whose small numbers exaggerate decreases) occurring in Tennessee with a 27.3
percent decrease from 1992 to 1996. At the same time, the number of operations with milk cows has decreased
across the board, except for no change in Alaska and New Hampshire. Herd size also increased
3-6
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from 1991 to 1996 in every state except Arkansas, New Hampshire, Alaska, and Wyoming. The most notable
changes occurred in Alabama, New Mexico, and South Carolina, where herd sizes increased more than 100 percent
(APHIS, 1996b).
Table 3-6 presents the most recent inventory of the number of dairy operations by size class for selected states for
1997 and 1998. Table 3-7 presents the most recent inventory of milk cows (as a percent of inventory) by size class
for selected states in 1996 and 1997.
Table 3-6. Milk cows: number of operations by size group, selected states, and United States, 1997-1998.a
State
1-29 Head
30-49 Head
50-99 Head
100-199 Head
200+ Head
Total
1997
1998
1997
1998
1997
1998
1997
1998
1997
1998
1997
1998
Arizona
190
180
0
0
0
0
10
10
100
100
300
290
California
570
500
100
90
130
120
300
290
1,800
1,800
2,900
2,800
Colorado
630
610
30
40
50
50
70
70
120
130
900
900
Florida
340
350
10
10
30
30
40
40
180
170
600
600
Georgia
300
230
20
20
140
130
200
190
140
130
800
700
Idaho
430
350
150
130
280
250
250
250
290
320
1,400
1,300
Illinois
430
330
420
430
880
780
330
320
40
40
2,100
1,900
Indiana
2,100
1,700
500
500
700
700
250
250
50
50
3,600
3,200
Iowa
1,300
1,010
1,300
1,200
1,650
1,500
480
520
70
70
4,800
4,300
Kentucky
1,500
1,300
730
650
990
900
330
300
50
50
3,600
3,200
Maryland
190
160
130
130
480
440
240
220
60
50
1,100
1,000
Michigan
1,100
1,000
900
850
1,300
1,200
880
830
220
220
4,400
4,100
Minnesota
2,100
1,700
4,100
3,600
3,800
3,600
830
850
170
250
11,000
10,000
Missouri
1,800
1,500
700
680
900
800
540
560
60
60
4,000
3,600
New Mexico
550
340
0
0
10
10
10
10
130
140
700
500
New York
1,800
1,700
2,000
2,000
3,700
3,300
1,300
1,200
400
400
9,200
8,600
North Carolina
570
520
60
60
210
200
260
230
100
90
1,200
1,100
Ohio
3,800
3,200
800
800
1,400
1,400
400
500
100
100
6,500
6,000
Oregon
530
370
50
20
150
140
210
210
160
160
1,100
900
Pennsylvania
2,600
2,300
3,800
3,800
3,900
3,800
1,000
1,100
200
200
11,500
11,200
Tennessee
300
260
290
240
540
520
300
300
70
80
1,500
1,400
Texas
1,200
800
100
100
400
300
700
600
600
700
3,000
2,500
Utah
300
320
70
70
190
170
210
210
130
130
900
900
Vermont
150
150
450
400
1,000
950
350
350
150
150
2,100
2,000
Virginia
550
500
130
110
520
500
400
390
100
100
1,700
1,600
Washington
750
540
70
70
180
120
320
300
380
370
1,700
1,400
Wisconsin
5,000
4,600
9,500
8,500
9,600
8,900
2,530
2,550
370
450
27,000
25,000
Other States
8,700
6,900
2,000
1,800
3,800
4,000
2,000
2,250
700
740
17,200
15,690
Total
39.780
33.420
28.410
26.300
36.930
34.810
14.740
14.900
6.940
7.250
126.800
116.680
1 An operation is any place having one or more head of milk cows on hand at any time during the year.
Source: NASS, 1998.
3-11
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Table 3-7. Milk cows: percent of inventory by size group, selected
states, and United States, 1996-1997.a
State
1-29 head
30-49 head
50-99 head
100-199 head
200+ Head
1996
1997
1996
1997
1996
1997
1996
1997
1996
1997
Arizona
0.2
0.2
-
-
-
-
0.8
0.8
99.0
99.0
California
0.1
0.1
0.3
0.3
0.8
0.8
3.8
3.8
95.0
95.0
Colorado
2.4
1.5
1.5
2.0
5.1
5.0
13.0
14.5
78.0
77.0
Florida
0.3
0.3
0.2
0.2
1.5
1.5
3.0
3.0
95.0
95.0
Georgia
1.1
1.0
0.9
1.0
11.0
10.0
30.0
29.0
57.0
59.0
Idaho
1.0
0.7
2.3
1.9
7.2
5.9
13.5
12.5
76.0
79.0
Illinois
3.0
2.0
11.0
11.0
49.0
47.0
28.0
30.0
9.0
10.0
Indiana
13.0
14.0
15.0
16.0
36.0
35.0
24.0
22.0
12.0
13.0
Iowa
8.0
6.5
19.0
19.0
43.0
40.0
23.0
26.0
7.0
8.5
Kentucky
8.5
7.0
17.0
16.0
42.0
41.0
25.0
27.0
7.5
9.0
Maryland
2.7
2.7
5.3
5.3
36.0
37.0
35.0
35.0
21.0
20.0
Michigan
5.0
4.0
11.0
10.0
28.0
27.0
35.0
35.0
21.0
24.0
Minnesota
7.0
6.0
26.0
23.0
41.0
41.0
17.0
17.0
9.0
13.0
Missouri
9.0
8.0
15.0
15.0
33.0
32.0
34.0
36.0
9.0
9.0
New Mexico
0.9
0.7
-
-
0.4
0.4
0.7
0.9
98.0
98.0
New York
2.7
2.6
11.3
11.4
37.0
35.0
28.0
28.0
21.0
23.0
North Carolina
1.5
1.5
2.5
2.5
17.0
16.0
41.0
41.0
38.0
39.0
Ohio
13.0
12.0
13.0
13.0
40.0
41.0
22.0
23.0
12.0
11.0
Oregon
2.0
2.0
2.0
1.0
13.0
12.0
31.0
30.0
52.0
55.0
Pennsylvania
6.0
5.0
23.0
22.0
41.0
41.0
20.0
22.0
10.0
10.0
Tennessee
3.5
2.5
9.5
7.5
33.0
33.0
37.0
36.0
17.0
21.0
Texas
1.2
0.9
1.0
1.1
7.8
7.0
24.0
23.0
66.0
68.0
Utah
1.3
1.3
2.7
2.7
16.0
14.0
31.0
31.0
49.0
51.0
Vermont
1.0
1.0
11.0
9.0
39.0
39.0
24.0
25.0
25.0
26.0
Virginia
3.0
3.0
4.0
4.0
30.0
29.0
40.0
40.0
23.0
24.0
Washington
0.9
0.7
1.1
1.0
5.0
3.3
20.0
19.0
73.0
76.0
Wisconsin
5.1
4.5
26.0
25.0
41.0
40.0
21.0
22.0
6.9
8.5
Other States
4.0
3.5
9.0
8.5
31.0
31.0
23.0
23.0
33.0
34.0
Total
4.0
3.5
12.0
11.5
27.0
26.0
20.0
20.0
37.0
39.0
a Percents reflect average distribution of various probability surveys conducted during the year but are based primarily on
beginning-of-year and mid-year surveys.
Source: NASS, 1998.
3.4 Waste Management Systems
The type of housing system affects the quantity of bedding or dilution water used in a manure management system.
This, in return, influences the manure characteristics and selection of collection, transfer, storage, and transport
equipment. The basic components of dairy manure management systems are shown in Figure 3-4. In addition to the
components shown by Veenhuizen et al. (1998), manure is also stockpiled in (or outside of) dry lots similarly to
stockpiling for beef feedlots described in Chapter 4.
Solid wastes are usually associated with bedded loafing barns, stanchion stalls, and dry lots where the solids content
is greater than 18 percent. Fresh manure has a solids content of 12 percent and can be handled as a semisolid or as a
solid if bedding is added. (Semisolid manure has a solids content ranging from 10 to 16 percent. For fresh manure to
be handled as a solid, 12 pounds of bedding would be needed for every 100 pounds of fresh manure.) Handling
manure as a solid or semisolid minimizes the volume of manure that is handled. (Milking center wastes would
typically be managed separately as a liquid.) Solid storage can include a stacking slab or covered storage. One or
two walls are commonly provided to control leachate, ease load-out, reduce required
3-12
-------
SOLID HANDLING
LIQUID HANDLING
Figure 3-4. Basic components of solid and liquid manure systems
for a dairy (Source: Veenhuizen et al., 1992).
floor area, and screen manure. In high-rainfall regions, roofing on storage can be used to keep precipitation out so
that manure can continued to be handled as a solid or semisolid. Rainwater that does fall on uncovered storage can
be drained with a picket-dam structure. Solid manure is usually transferred and loaded into storage using a tractor-
mounted front-end loader, elevator stacker, or solid piston pump. Manure is then unloaded from storage using a
front-end loader or is spread as a solid or semisolid in a box or flail spreader.
Fresh manure can be treated as a slurry if 30 gallons of dilution water (from precipitation, runoff, or milking center
wastewater) is added per 100 gallons of the fresh manure, resulting in a solids content of 4 to 10 percent. Slurry
systems maintain more plant nutrients from the waste than lagoons and are often used where geology is unsuitable
for lagoons. Operations may switch from the solid to slurry system to reduce labor costs. Slurry systems are also
known as liquid tank systems.
Manure with a solids content of less than 4 percent is considered liquid. This is usually the effluent from the liquid-
solid separation process, milking centers, or supernatant from lagoons. If there is no solids separation performed,
about 250 gallons of dilution water must be added per 100 gallons of fresh manure, to reduce the solids content to
below 4 percent. Liquid systems are usually associated with the lagoon waste management system and are favored
by large operations because labor costs are minimized and a flushing system can be used to collect and transport
waste to the lagoon. Flushing systems have the primary advantage of being automated. Manure can also be
collected and removed from the barn with a tractor-mounted scraper, mechanical alley scraper, flushing system, or
slotted floor. Based on the site conditions, manure is stored in earthern basins, belowground tanks, or aboveground
tanks. Liquid manure is transferred to storage using gravity pumps, large piston pumps, pneumatic pumps, and
centrifugal chopper pumps. Some liquid-storage structures allow for agitating the waste prior to irrigating or loading
a tank spreader (typical of belowground tanks). If solids are not agitated (common in lagoons), they will accumulate
in the structure, reducing storage capacity.
The remainder of this section provides a more detailed description of the equipment and typical practices used to
manage dairy manure.
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3.4.1 Nutritional Strategies
Nutritional strategies for dairy cattle to minimize nutrient excretion have not been adequately reported in the
literature at this time although anecdotal evidence suggests opportunities for decreased nutrient excretion exist. One
objective of future research might be to optimize the balance between milk production and nutrient excretion.
Surveys conducted on dairy farms in New York have shown that feed imports account for 62 to 86 percent of the
total nitrogen input of a farm: 64 to 76 percent of this nitrogen remains on the farm in initial manure excretions.
Likewise, feed accounts for 45 to 80 percent of the total phosphorus input to the farm, and 68 to 81 percent of the
total phosphorus input remains on the farm. For potassium, 16 to 62 percent of the inputs are represented in the feed,
while 67 to 89 percent of the potassium inputs remain on the farm (Grusenmeyer and Cramer, 1997).
3.4.2 Waste Collection
As shown in Table 3-8, about three-fourths (74 percent) of dairy operations with less than 100 milk cows and one-
third (34.7 percent) of dairy operations with 100 to 199 milk cows use a gutter cleaner (APHIS, 1996c). Gutter
cleaners are frequently used in confined stall dairy barns. The gutters are usually 16 to 24 inches wide, 12 to 16
inches deep, and flat on the bottom. Either shuttle-stroke or chain and flight gutter cleaners are used to clean the
gutters. Shuttle-stroke gutter cleaners are driven by electric motors. They have paddles that pivot on a drive rod,
which travels alternately forward for a short distance and backwards, for the same distance. The paddles move the
manure forward on the forward stroke, then collapse on the drive rod on the return stroke, forcing the manure down
the gutter.
Table 3-8. Percent of operations by method of removing manure from cow housing areas.
Fewer than
100-199
200 or
Method
100 Head
Head
More Head
Total
Gutter cleaner
74.0
34.7
9.0
63.2
Alley scraper (mechanical or tractor)
50.2
82.4
85.0
57.7
Alley flushed with water
0.2
4.3
26.6
2.8
Other
1.3
0.5
0.1
1.1
Source: APHIS, 1996c.
More than 80 percent of operations with more than 100 milk cows use a mechanical or tractor scraper (APHIS,
1996c). Tractor scraping is more common since the same equipment can be used to clean outside lots as well as
freestalls and loose housing. A mechanical alley scraper consists of one or more blades that are wide enough to
scrape the entire alley in one pass. The blades are pulled by a cable or chain drive that is set into a groove in the
center of the alley. The system is run by a 0.5- to 1-horsepower electric motor and controls. A timer can be set so
that the scraper runs two to four times a day, or continuously in colder conditions to prevent the blade from freezing
to the floor. Scrapers reduce daily labor requirements, but have a higher maintenance cost due to corrosion and
deterioration.
Outside lots usually produce semisolid or solid waste from lot scrapings and sheltered bedded packs, while lot runoff
is liquid. The solids and semisolids can be moved to storage using a tractor scraper or front-end loader. Runoff is
commonly drained to a settling basin and/or solids separator. The removed solids can be spread as fertilizer and soil
conditioner, mixed as a feed for heifers, or composted and used for freestall bedding. The separated liquid wastes
can be stored. Runoff from areas without livestock impact do not need to be handled in the manure management
system. Instead, this runoff is diverted away from outside lots, reducing the total volume into the system.
Flush systems are suitable for cleaning freestall alleys, parlor floors, and holding areas when temperatures are above
25 eF. One-fourth (26.6 percent) of operations with more than 200 milk cows flush alleys with water (APHIS,
1996c). Required flush water volume varies according to alley width and slope (see Table 3-9). The values in Table
3-9 were developed to provide an initial flow depth of 3 inches, a velocity of 5 feet per second, and a 10-second flow
duration for alley lengths up to 150 feet.
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Typical freestalls with alley widths of 10 and 12 feet and a 2 percent floor slope would require about 2,750 gallons
per flush. Thus, to flush the alley two or three times a day would require 5,500 to 8,250 gallons per day. To reduce
the amount of fresh water needed for flushing, flush water can be recycled (MWPS, 1997). Of those operations that
flush alleys, 54.4 percent recycle water for multiple flushings (APHIS, 1996c). A solids separation system is used if
the flush water is recycled. Note that only fresh water is used to clean the milking parlor area.
Table 3-9. Flush parameters.
Alley Slope
Flow Depth
Flow Rate
Flush Volume
(%)
(in)
(gpm/ft alley width)
(gal/ft alley width)
1.0
7.0
1,306
220
1.5
5.0
933
156
2.0
4.0
747
125
2.5
3.4
635
106
3.0
3.0
560
94
Source: Adapted from MWPS (1997).
Milking center effluent is a liquid, but it contains milk solids, manure, grit, detergents, and sometimes feed. When
dairy barn manure is handled and stored as a slurry or liquid, the milking center effluent can be mixed in with the
animal manure, serving as dilution water to ease pumping. If a gravity system is used to transfer manure to storage,
milking center effluent may be added at the collection point in the barn.
Concrete slotted floors allow manure to be quickly removed from the animal environment with minimal labor cost.
Manure falls through the slotted floor or is worked through by animal traffic. The waste is then stored in a pit
beneath the floor or removed with gravity flow channels, flushing systems, or mechanical scrapers. Mechanical
scrapers are not common under slotted floors because of the difficulty associated with repair and replacement
(MWPS, 1997). The storage of animal and milking center waste in a pit beneath slotted floors combines manure
collection, transfer, and storage. Problems may arise; however, if the pits cause manure gasses and moisture to build
up in the animal environment. The excess gas and moisture can also be corrosive, causing premature deterioration of
metal gusset plates on trusses. Other disadvantages include expensive construction and difficulties in proper solids
removal (MWPS, 1997). If the gravity flow channel beneath the slotted floor has straight sides, the collected manure
can be removed by flushing.
3.4.3 Waste Storage
Storage planning should consider all farmstead operations, building locations, and prevailing summer winds. The
American Society of Agricultural Engineers (ASAE) indicates that manure storages are to be located at least 100 feet
away from water supplies and 50 feet from the milking center (ASAE EP393.2 DEC97). According to a recent
survey, three-fourths (73.8 percent) of dairy operations have a distance of 500 or more feet between manure storage
and the nearest waterway or body of water, while 14.6 and 11.6 percent of dairy operations have a distance of 200 to
499 feet and less than 200 feet between manure storage and the nearest waterway or body of water. More than 80
(81.1) percent of dairy operations have a distance of 200 or more feet between manure storage and the nearest well
(APHIS, 1996c). If storage units are located over shallow, creviced bedrock or in gravel beds, construction
procedures and materials that prevent seepage to the ground water should be used (ASAE EP393.2 DEC97).
Belowground storage units should be avoided in areas with high water tables unless drains are installed to
permanently lower the water table (ASAE EP393.2 DEC97). ASAE also recommends that storage units have a
storage capacity of up to 210 days in colder climates and as little as 45 days in warmer climates (ASAE EP393.2
DEC97).
Table 3-9 summarizes the percent of operations by waste storage system used. Operations with 200 or more milk
cows have a larger proportion of operations with anaerobic lagoons without covers (46.7 percent), provide outside
storage within dry lots or pens (22.0 percent), and provide slurry storage in tanks (17.5 percent) than operations with
fewer than 200 milk cows. Operations with 200 or more milk cows also have a larger proportion of aerated lagoons
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(8.3 percent) than other operations, but overall are a smaller percentage of operations than operations with anaerobic
lagoons. Below-floor slurry/deep pits and slurry storage in earthen-basins are more prevalent in operations with 100
or more milk cows. For those operations with lagoons, 84 percent use a single-stage lagoon while 16.6 percent use a
multiple-stage lagoon. Interestingly, only 2.3 percent of operations separate solid waste from liquids before
placement in some type of storage tank or lagoon while 29.5 percent do not separate solids; 68.2 percent do not use
storage tanks or lagoons (APHIS, 1996c).
Table 3-9. Percent of o
derations by waste storage system.
Fewer than
100-199
200 or
Method
100 Head
Head
More Head
Total
Below-floor slurry or deep pit
4.7
19.6
16.9
7.9
Slurry storage in tanks
3.2
10.9
17.5
5.4
Slurry storage in earthen-basin
13.5
25.2
27.8
16.3
Anaerobic lagoon with cover
0.2
0.3
1.1
0.3
Anaerobic lagoon without cover
5.7
18.2
46.7
10.7
Aerated lagoon
0.5
3.3
8.3
1.5
Manure pack (inside barn)
22.3
20.4
14.1
21.4
Outside storage for solids (not in dry lot or pen)
37.9
33.0
30.1
36.6
Outside storage within dry lots or pens
14.8
11.5
22.0
14.9
Solids in a building without cattle access
2.8
4.1
2.4
3.0
Other
2.1
1.8
1.6
2.0
Source: APHIS, 1996c.
3.4.3.1 Solid and Semisolid Manure Storage Units
When bedding is used and water dilution is avoided, dairy manure can be stacked and stored on paved areas with
appropriate controls for drainage. If solid manure from the bedded areas is combined with manure scraped from
freestall or feeding alleys, the result is typically a semisolid mixture that needs to be confined by walls constructed
from concrete or pressure-treated wood. These structures are filled using a bottom-loading piston pump or a push-
off ramp, and they are emptied using a front-end loader or manure auger. If these storage units are not covered,
picket dams or floor drains can be used to allow rainwater to drain to a holding tank or detention pond. Picket dams
consist of vertical slots about Vi inch wide (ASAE EP393.2 DEC97) between standing planks or pickets holding
solid manure but allowing liquids, such as rainwater, to drain. Detention ponds are designed for a 25-year, 24-hour
return storm and 1-foot freeboard (ASAE EP393.2 DEC97). Manure from roofed storage units would typically be
dryer than that from unroofed storage units.
3.4.3.2 Liquid and Slurry Storage Units
Milking centers may produce up to 50 percent of the waste volume, but because of the dilute nature of milking center
effluent, only about 15 percent of the total solids. This is mainly due to the many cleaning and flushing procedures
used to keep the milking area sanitary. About 5 to 10 gallons of fresh water per cow milked per day is used in
milking centers where flushing does not occur. In milking centers that use manure flushing and automatic cow
washing, water use can climb to 150 gal/d/cow with 10 percent of the water usage associated with parlor, cleanup,
and sanitation; 30 percent with cow washing; 50 percent with manure flushing; and 10 percent with miscellaneous
uses. Therefore, milking center wastes and runoff from corrals and open feeding areas are dilute enough to handle as
a liquid that can be stored in steel or reinforced concrete tanks, earthen basins, or retention ponds.
The allowable storage depth of belowground tanks is limited by the soil mantle depth over bedrock, the water table
elevation, and the pump's effective lift. Aboveground tanks range in size from 10 to 30 feet high and 30 to 120 feet
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in diameter. They are made of concrete staves, reinforced concrete, preformed concrete panels, and steel.
Compared to earthen basins they are expensive and usually not used to store runoff or dilute wastes. However, in
areas where basins are limited by space, high ground water, or shallow and creviced bedrock, or where earthen
basins are not aesthetically acceptable, aboveground storage tanks are a good alternative.
Earthen basins allow long-term storage at low to moderate investment. Currently, these structures can be unlined or
they can be lined, depending on location and unloading methods, with clay, a synthetic material, or concrete. The
inside bank slopes common for most soils are from 2:1 to 3:1 (run:rise). The outside side slopes are typically 3:1.
Holding ponds are used for temporary storage of runoff water from a settling basin, or the effluent from a solids
separator. Lagoons that receive large quantities of manure, such as from the holding area or the cow feed yard,
usually operate in an anaerobic mode. In the anaerobic lagoon, the nutrient concentration of the supernatant, or the
upper liquid layer of the lagoon, is greater than that in an aerobic lagoon. Sludge accumulates at a rate of about
0.073 ft3/lb of total solids added to the lagoon, or about 266 cubic feet per year for each 1,000-pound lactating cow
equivalent. Lagoons receiving wastewater from only the milk house of the milking parlor generally exhibit a
nonviscous supernatant and operate in an aerobic mode. Also, sludge accumulates at a slow rate in such lagoons.
3.4.4 Waste Disposal and Use
Table 3-10 summarizes the percentage of dairy operations that implement various manure disposal practices.
Most (98.9 percent) operations apply manure to land owned or rented by the operator. Larger operations have also
exploited other disposal options including selling, composting, and giving the manure away more than smaller
operations. Larger operations also tend to analyze manure for nutrient content more than smaller operations, yet less
than one-half of all operations establish manure application rates based on manure nutrients and/or crop needs
(APHIS, 1996c). According to a study in Wisconsin of 1,179 farmers, less than 29.8 percent of operations made an
effort to credit manure nitrogen on their most productive corn field. Of those operations that credited manure
nitrogen, 66 percent underestimated manure nitrogen by 11 percent or more, 28 percent overestimated manure
nitrogen by 11 percent or more, and 6 percent estimated manure nitrogen within 10 percent of the University of
Wisconsin guidelines. In all, less than 2 percent of all farmers spreading manure on corn ground are crediting
manure nutrients with any degree of accuracy (Nowak et al., 1998).
For those operations that applied manure to their own land, 30.4, 25.5, 10.8, and 33.3 percent of operations apply
manure on a daily, weekly, monthly, or less frequent basis, respectively, during summer months. During winter
months, 46.5, 14.7, 7.8, and 31.0 percent of operations dispose of manure on a daily, weekly, monthly, or less
frequent basis, respectively (APHIS, 1996c).
Broadcast spreaders are the most prevalent equipment used to apply manure regardless of operation size, but they are
more common on small operations and can be used for solid or semisolid waste. Box-type spreaders have moving
aprons that move the load rearward to beaters. Flail-type spreaders use chains attached to a shaft that revolves at
high speed to flail the manure out of the tank.
Larger operations have a higher frequency of irrigation systems such as center pivots, traveling guns, stationary
hand-carried sprinklers, and gated pipe for disposing of liquid wastes. The type of system used depends on trade-
offs related to operation size, capital costs, labor availability, and the type of land. Larger operations tend to use
center pivots or traveling guns. Center pivots have the highest capital cost and lowest labor requirements. Traveling
guns require less capital and more labor. Small operations can use stationary hand-carried sprinklers if labor is
available. In certain circumstances, liquid wastes from milking centers or lagoons can be surface-irrigated with gated
pipe. Gated pipe systems can be made from polyethylene pipe with holes drilled at 30- to 40-inch intervals. These
holes should be small enough to allow flow to be distributed throughout the length of the pipe, but large enough to
prevent clogging by small solids. Commercial systems with adjustable gates are also available. Conventional
irrigation pumps or centrifugal pumps can used if installed to prevent surface debris and sludge from entering the
intake.
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Table 3-10. Percent of operations by waste disposal practice.
Method
Fewer than
100 Head
100-199
Head
200 or
More Head
Total
Disposal Method
Applied on land owned or rented by operator
99.4
98.6
94.7
98.9
Sold or received other compensation
0.8
2.7
17.5
2.3
Gave away
4.9
8.7
22.6
6.8
Composted
3.3
6.2
16.3
4.7
Application Method
Irrigation
3.1
11.2
40.5
7.0
Broadcast/solid spreader
90.6
85.1
75.8
88.7
Slurry (surface application)
17.7
38.5
44.6
22.7
Slurry (subsurface injection)
3.6
5.9
8.6
4.3
Other method
0.0
0.4
1.0
0.1
Practices
Analyzed nutrient content of manure
10.3
26.4
28.6
14.0
Established manure application rate based on
manure nutrients and/or crop needs
41.7
50.5
43.3
43.2
Applied manure a minimum of 50 feet from
waterbodies
77.9
77.2
82.5
78.1
Incorporated manure into soil within 24 hours after
application
15.8
22.8
31.5
17.9
Source: APHIS, 1996c.
Settling tanks can also be used in combination with filter strips. Once the solids are removed, grass filter strips can
provide surface disposal of the effluent. Filter strips are an effective means of wastewater treatment for dairy
facilities producing less than 500 gallons per day from the milking center. The wastewater flows through the filter
strip and the water evaporates while the fine solids and bacteria remain. Organic compounds are degraded
aerobically so that little odor is given off, and phosphorus and nitrogen are consumed by plants. The soils most
compatible with this disposal system are fine-textured soils with moderate permeability, such as sandy loam to clay
loam. Filter strips might not be sufficient where the soil is too sandy. Good cover crops to use, because of their
tolerance to moisture and ability to develop thick ground cover (thus reducing erosion), are tall fescue and reed
canary grass. Other crops might be selected because of uptake characteristics or increased usefulness. The
vegetation is periodically harvested and fed to livestock, used as a bedding or soil amendment, or used as a fuel.
Slurries can be pumped with chopper pumps into tank wagons drawn by tractors. Tank wagons have capacities of
1,000 to 3,000 gallons. For large operations or if longer hauls are necessary, a tank truck may be more cost-
effective. Tank wagons spread the liquid on the soil or may be equipped with knives to inject the waste into the soil.
Although injection reduces odors and nitrogen loss, substantial power is required to pull the tank wagon and
injectors at a reasonable speed. Injection is not an option if the soil is frozen or too rocky.
In general, sludge should be removed when sludge levels have reached about two-thirds of the normal pond depth
(NSW, 1994). There are several options for removing the sludge. The decision of which to use depends on
producer preference, the availability of the necessary equipment and contractors, and the costs involved. Hydraulic
dredging removes the sludge as a liquid/slurry by using a large-capacity pump to mix the whole pond contents and
keep solids suspended while pumping the slurry. Sludge can then be transferred directly to a land disposal site, or a
vacuum tanker can be used to distribute the wastes to land whenever desired. This type of sludge removal is often
done by septic tank pump-out contractors or specialized waste management contractors. If liquid is pumped off and
in-flow from the milking center is by-passed to contour drains or alternative disposal systems for a short time, the
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accumulated sludge will dry slightly, allowing removal as a semisolid with a long-arm excavator. Sludge removal is
usually timed so that the sludge can be land applied immediately.
3.5 Example Systems
This section provides a summary of dairy waste management systems used today. Some examples, in particular
those based on personal communication with knowledgeable experts, may be a general characterization of operations
in that state or region rather than a specific system.
3.5.1 Connecticut (Neafsy, personal communication, 1998)
Dairy waste is usually handled as a liquid. Historically, the storage volume required in liquid systems was 6 months'
capacity. Recently, it has become important to consider nutrient management as the basis for waste management
systems. This has led to an increase in the suggested storage volume to 9 months' capacity. The typical storage unit
has historically been earthen storage lagoons. Currently, however, polyethylene or PVC liners have been suggested
to protect leaching from the lagoons to groundwater in cases where permeability of the surrounding soil is too high.
Liquid waste is applied using irrigation if the crop is near the waste storage facility. The most common application
method, however, is to use conventional spreaders. Application is done when the crops can best utilize the nutrients.
For corn crops, application is completed in April or May. Once applied, the manure is immediately incorporated and
corn is planted. For hay crops, a light application is performed after harvest.
Solids are a minor part of the typical dairy waste management systems in the Northeast. In fact, about 30 to 40
percent of producers put the milk room and silage leachate in with the manure so that all waste is handled as a liquid.
In smaller operations where handling of solids is more practical, solids are composted and used as bedding.
Runoff is diverted using roofs, gutters, and graded land into settling basins and vegetative filter areas that are set up
in a pattern described as an "ice cube tray." This pattern allows detention and infiltration of some of the water
before the runoff enters any surrounding waterbodies.
3.5.2 Idaho (Shoemaker, personal communication, 1998)
In the wetter areas of the West, wastes are scraped from corrals, while in drier areas the wastes are left mounded in
the corrals. Barn wash water and storm water that runs off from corrals are stored in earthen ponds designed for 6
months of storage. Liners are necessary in cases where permeability of the surrounding soils exceeds certain values.
These earthen ponds are emptied in early spring just before the growing season. Sprinkler systems are the current
trend for applying liquid waste because minimal labor is required.
Wastes from the holding pens are stacked as solids. The solids are applied to the land using manure spreaders.
Solids application and immediate incorporation are usually performed in the fall after the crops have been harvested.
Storm water handling is most important through the winter period; therefore, clean water is diverted off site through
earthen runoff diversions or pipe lines. Roofing or gutters to divert runoff have received limited acceptance due to
the drier climate in the mountain region. Separators are not common due to the dry climate, but have recently
become more important in some dairy operations during spring thaw.
3.5.3 Nebraska (Bodman, 1995)
In Nebraska, many dairy producers still rely on daily scrape/haul methods for managing manure. This is appropriate
as long as land area is available to allow spreading throughout the year without exceeding agronomic nutrient needs
and as long as runoff is controlled to prevent contaminated runoff from leaving the owner's property. Because of
increasing herd sizes, which have increased environmental and water quality concerns and have created a need for
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more efficient use of labor, many dairy producers are considering various storage options. In Nebraska, a minimum
of 180 days of storage is required. The storage options include underfloor storage, aboveground tub or tower silos,
slotted dams, earthen-bank storage units, and lagoons.
Underfloor storage is used for operations where daily labor and equipment are minimized. Manure enters the storage
through slotted floor or by scraping. The storage is constructed of reinforced concrete and is considered expensive.
The underfloor storage is divided into individual cells up to 50 by 50 feet. To remove the manure from an
underfloor storage system, the manure is agitated and handled as a slurry.
Aboveground tub or tower silos are used in areas with a shallow watertable or where bedrock exists. Costs and
handling methods are similar to those for underfloor storage. If these storage units are not covered, the usable depth
is 3 to 5 feet less than the total depth. Rainfall and duration of storage determine the volume available for storing
manure. It is important to provide sufficient storage depth at all times to allow accumulation of rainfall and runoff
from a 25-year, 24-hour precipitation event, which in Nebraska ranges from 3.5 inches to 5.7 inches from northwest
to southeast Nebraska.
Slotted dam storage units use an earthen-bank enclosure to store manure solids. This enclosure has a concrete floor
and access ramp. A separate earthen-bank impoundment is used to store the milking center effluent, precipitation,
and runoff from both parts of the storage system. This type of storage works best for producers using fibrous
bedding and fibrous feeds such as long hay and corn silage. Slotted dams are not well suited for operations that use
sand bedding with a high haylage ration. If manure is a semisolid, it is hauled to the fields using open-top tanks,
whereas liquid manure is usually land-applied via irrigation.
Earthen storage units are well suited to operations having a low to moderate amount of lot drainage or runoff. This is
also the least expensive storage option. The storage unit should be agitated so the settled and floating solids are put
into suspension. The resulting slurry is hauled to the fields using an enclosed tank spreader. Earthen-bank storages
are designed with considerations for precipitation, runoff, manure production rate and duration of storage.
3.5.4 Kansas (Melton, personal communication, 1998)
Solid manure is scraped from the lots and stockpiled. It is handled with heavy equipment such as front-end loaders
or scrapers and spread onto cropland or pastureland using a manure spreader.
Building washdown water, liquid manure, and lot runoff are directed into earthen ponds or concrete-lined holding
tanks. No special lining considerations are usually necessary because the highly aggregated clay that makes up most
of the soils in the area prevent-leaching. The holding tanks and ponds should be designed with a 1-year holding
capacity due to the possibility of frozen ground during the winter months preventing application. Liquids are directed
to the holding ponds by earthen diversions, open channels, or pipes. Holding tanks are emptied using "honey
wagons" or liquid manure spreaders, while ponds are emptied using irrigation equipment.
3.5.5 Oregon (Moore and Hart, 1997)
Dairy manure is collected using tractor scrape units or hydraulic flush systems. In the more temperate areas, flushing
is the main method used for larger herds. This system reduces labor, provides excellent barn cleaning, and is easily
controlled. During wet weather or when soils are at or near saturation, field spreading is not possible so this system
may require large storage units.
One of the most common treatment methods is the use of a mechanical separator. Most flush collection units have
separators, which are used to remove the large particles from the waste stream. The most common separator is the
static inclined screen. In such a separator, manure passes over an inclined screen. The liquid passes through the
screen while the solids continue over and flow off the end of the screen. The solids can then be handled with other
solid wastes. The purpose of the separator is to reduce the buildup of solids in ponds and lagoons. The separation
also allows for the liquid to be more easily pumped and reduces clogging in piping and sprinkler heads.
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In Oregon dairy manure application to cropland is usually limited by soil moisture content or nutrient loading rate.
Along the Washington and Oregon coast, soil temperatures rarely drop below freezing so that manure nitrogen is
slowly converted into the soluble nitrate form available to plants. The cool temperatures allow minor growth of
pasture grass, but the presence of high winter rainfall makes this time one of the highest concerns in terms of runoff.
Therefore, manure applications in late fall must match the limited uptake of the cover crop. By January and
February the soil temperatures increase enough so that the growth of the cover crop is plentiful, allowing for up to 30
kg of nitrogen/month-ha to be spread. In the Willamette Valley, where some soil temperatures drop below freezing,
dairy operators interseed rye in corn so that a growing fall-winter crop can be used to take up nitrate from fall and
winter manure applications.
3.5.6 California (Meyer et al., 1997)
Regulations regarding manure storage capacity and use have existed in California since 1984. Nevertheless herd size
has increased to 979 lactating and dry cows, total farm acreage has increased from 501 to 685 acres, and land
available for manure application has increased from 379 to 505 acres. These regulations include a requirement that
storage must have the capacity to store rainfall that has been contaminated by manure and maintain storage capacity
for a 25-year, 24-hour storm event. The storage structure must also have the impermeability of a 10 percent clay
soil. Manure application must be done at proper rates. Meyer et al. (1997) determined the most commonly used
manure management practices were the following:
c The technique used most often for collecting manure is a combination of flushing and scraping (64.9 percent) or
just flush collection (77.1 percent),
c The most common storage systems are holding or storage ponds (95.9 percent); 59.5 percent of producers have
one pond and 24.3 percent have two ponds. The mean total storage capacity for waste liquids is 48.57 acre-ft,
with a mean of 115,673 ft2 of pond surface area. Evaporation ponds for temporary storage and disposal of waste
are used by 9.5 percent of the producers. The most popular system for solid-liquid separation is settling ponds
or basins (54.1 percent), while mechanical solid-liquid separators are used by 9.5 percent of the producers.
c Liquid manure and runoff that has accumulated in ponds are most often applied to the land through seasonal
(29.7 percent) oryear-round (33.8 percent) irrigation. Almost all (94.6 percent) producers include scraping solid
manure into piles as part of their solid manure collection system. Solid manure is disposed of most often by
field spreading or is sold.
3.5.7 Florida (Watts, personal communication, 1998)
Manure deposited on the pastures or on any unlined area is to be applied at an agronomic rate. If this is not possible,
the manure should be collected and applied at recommended rates that depend on the crops planted and the estimated
crop production rate. To collect all contaminated water and waste, which includes wash water, cooling water, and
wastewater, the concrete area is curbed, inlet boxes are employed, waterways are lined or drain pipes used, and the
waste is pumped to a waste storage facility.
Waste storage facilities are for temporary storage for contaminated water generated by the dairy. Facility storage
volume includes water from the facility's drainage area that comes into contact with the animal activities, normal
precipitation minus evaporation, waste water, manure, and the 25-year, 24-hour storm precipitation on the actual
facility surface. Storage facilities are either an excavated pond with an approved liner, a fabricated structure, or a
holding tank constructed of approved material.
The disposal method usually consists of a waste distribution system that includes a center pivot, a traveling gun, a
solid-set irrigation system, a linear irrigation system, or a honey wagon. The waste is applied to the crop at planned
agronomic rates. The soils at each waste application site are examined to determine whether to use nitrogen or
phosphorus as the soil limiting nutrient for application. Some dairies scrape the manure and apply it to designated
fields on the dairy; if not, the manure is hauled off site.
3-21
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3.5.8 Texas (Walker, personal communication, 1998)
Because of the drastic differences in climate in different areas of Texas, waste management practices differ from one
area to the next. The dairy farms tend to the larger, greater-than-l,000-head in Erath County and to the south and
west of Fort Worth. In eastern Texas, the farms tend to be smaller, family-owned operations. In the east, where the
rainfall amounts are generally higher and nutrient buildup on the land might lead to runoff, treatment lagoons based
on 140 to 160 days of storage are used. Often, these systems include a waste storage pond that the waste enters after
the treatment lagoon. Then the waste is land-applied based on a water budget The storage ponds are built for 30
days' capacity to match crop demand, or they may need up to 3 months' storage capacity to carry over into the winter
months when application is not feasible. Most of the large dairy farms in Texas are located in the western parts of
the state where rainfall amounts are quite small. On these operations, storage ponds are designed for enough
capacity to hold the water from a 25-year, 24-hour storm event and with enough settling time to allow the solids
holding the majority of the phosphorus to settle out.
In eastern Texas where perched water tables might also be a problem, earthen storage units require liners made of
treated local soil or proper soil imported from other areas. In western Texas where the climate is more arid, direct
surface application of waste is possible, with the runoff being pumped back into the system using special channels
and pipes surrounding the fields. Because of the climate in Texas, aboveground storage is not necessary except
possibly during the winter and spring in the wettest areas of eastern Texas.
Land application is usually done in the spring. Farmers often plant a small seed crop, such as clover, between their
regular crops to allow for plant uptake of nutrients. This makes it possible, in places such as southern Texas, to land-
apply liquid waste year-round.
Because of the large amount of wastewater produced, the most common type of application system is using
commercial pumping services to dewater the lagoons and apply the waste through traveling guns. Alternatively,
some operations have their own pumping system with underground pipes, polyethylene hoses, and traveling gun or
pivot sprinklers.
For the confined feedlot areas that collect waste in solid form, front-end loaders are typically used to collect and then
stack the manure. This is the system used more often by the drier western Texas operations. The solid waste is
field-applied using manure spreaders.
3.6 Bibliography
APHIS. 1993. National Dairy Heifer Evaluation Project, Contract Heifer Raising, . File ndhepcon.pdf accessed October 15, 1998. U.S. Department of Agriculture, Animal
and Plant Health Inspection Service.
APHIS. 1996a. National Animal Health Monitoring System, Parti: Reference of1996 Dairy Management
Practices, . File dr96desl.pdf accessed October 15, 1998.
U.S. Department of Agriculture, Animal and Plant Health Inspection Service.
APHIS. 1996b. National Animal Health Monitoring System, Partll: Changes in the U.S. Dairy Industry: 1991-
1996. . File dr96trnd.pdf accessed October 15, 1998. U.S.
Department of Agriculture, Animal and Plant Health Inspection Service.
APHIS. 1996c. National Animal Health Monitoring System, Part III: Reference of1996 Dairy Health and Health
Management, . File dry3-96.pdf accessed October 15, 1998.
U.S. Department of Agriculture, Animal and Plant Health Inspection Service.
Bennet, Myron, Donald Osborn, Charles D. Fulhage, and Donald L. Pfost. 1994. Economic Considerations for Dairy
Waste Management, .
3-22
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Bodman, Gerald R. 1995. Manure Management Storage Options for Nebraska: 1994-1995 Dairy Report. Nebraska
Cooperative Extension MP65-A. University of Nebraska-Lincoln.
Buckalew, Evelyn, and Phillip Norcross, eds. 1986. Dairy Manure Management: A Supplement to Manure
Management for Environmental Protection. Pennsylvania Department of Environmental Resources.
Commonwealth of Pennsylvania, Harrisburg, PA.
Evans, Shelby M. and Lori Sandman. 1997. Barnyard Runoff Management: An Information Source for Dairy
Farmers. Dairy Network Partnership.
Fulhage, Charles D. and Donald L. Pfost. 1993. Fertilizer Nutrients in Dairy Manure. Department of Agricultural
Engineering, University of Missouri-Columbia, .
Grusenmeyer, D.C. and T. N. Cramer. 1997. Symposium: Manure Management, A System Approach. Journal of
Dairy Science 80(10):2651-2653.
Lander, C.H., D. Moffitt, and K. Alt. 1998. Nutrients Available from Livestock Manure Relative to Crop Growth
Requirements. U.S. Department of Agriculture, Natural Resources Conservation Service, Resource
Assessment and Strategic Planning Working Paper 98-1. . Accessed October 15, 1998.
Melton, Charles. Design Engineer, NRCS-USDA, Salina, Kansas. Personal communication. September 2, 1998.
Meyer, D. Morse, I. Garnett, and J.C. Guthrie. 1997. A Survey of Dairy Manure Management Practices in
California. Journal of Dairy Science 80(8): 1841-1845.
MWPS. 1997. Dairy Freestall Housing and Equipment. Midwest Plan Service, Iowa State University, Ames, Iowa.
Moeller, N. J. and W.H. Friday. 1976. Solid Waste Handling for Dairy Operations.
.
Moore, J. A. and J.M. Hart. 1997. Manure Management System Design Strategies: How and Why. Journal of Dairy
Science 80(10):2655-2658.
Morrill, James L., James R. Hunham, and Edward P. Call. 1991. Raising Dairy Heifers. Cooperative Extension
Service, Kansas State University, Manhattan KS.
NASS. 1998. Agricultural Statistics 1998. . File 98_ch7.pdf
accessed October 19, 1998.
Neafsy, Joe. Connecticut State NRCS Water Quality Specialist, Agricultural Team, NRCS-USDA. Personal
correspondence. September 1, 1998.
Nowak, P., R. Shepard, and F. Madison. 1998. Farmers and Manure Management: A Critical Analysis. In Animal
Waste Utilization: Effective Use of Manure as a Soil Resource, ed. J.L. Hatfield and B.A. Stewart. Ann
Arbor Press, Chelsea, Michigan.
NSW Dairy Farmers' Association and NSW Agriculture. 1994. Managing Dairy Farm Wastes.
Pfost, Donald L. and Charles D. Fulhage. 1995. Dairy Waste Management Systems in Missouri.
.
3-23
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Shoemaker, Art. Idaho State NRCS Engineer. Personal communication. August 31, 1998.
Stull, Carolyn, E. DePeters, and G. Beall, eds. 1996. Dairy Care Practices: Animal Care Series. Dairy Workgroup,
University of California Cooperative Extension.
Tamminga, S. 1996. A Review on Environmental Impacts of Nutritional Strategies in Ruminants. Journal of Animal
Science 74(12):3112-3124.
USD A, NRCS. 1992. National Engineering Handbook: Agricultural Waste Management Field Handbook. U.S.
Department of Agriculture, Natural Resources Conservation Service.
Veenhuizen, Michael A., D.J. Eckert, Kevin Elder, Jay Johnson, William F. Lyon, Karen M. Mancl, and Gary
Schnitky. 1998. Ohio Livestock Manure and Wastew ater Management Guide. Bulletin 604. Ohio State
University Extension, Ohio, .
Walker, Jerry. Texas NRCS Water Management Engineer, NRCS-USDA, Temple, TX. Personal communication.
September 8, 1998.
Watts, Nga. Agricultural Engineer, NRCS-USDA, Florida. Personal communication. September 10, 1998.
3-24
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4.0 Beef
4.1 Introduction
Beef production has two primary phases—the cow-calf phase, in which calves reach maturity (usually on pasture),
and the finishing phase, in which cattle are generally confined and fed a strict diet to promote weight gain and to
improve the quality of meat.
4.1.1 Cow-calf Operations
Most cow-calf operations use pasture for calving. Less than 10 percent of operations surveyed had a cow or heifer
that calved in a calving lot or confined shed/barn, and only 21.1 percent of operations had a cow or heifer that calved
in a special calving pasture or shelter (APHIS, 1997a). In 1993, 81.2 percent of the calves were born from January
through May. About 2.9 percent of calves are born dead, 1.8 percent die within 24 hours, and 2.5 percent die by 3
weeks for a cumulative percentage of 7.2 (APHIS, 1994d). Calves from replacement heifers have a cumulative
mortality in the first 3 weeks of 13.9 percent, while calves from cows have a cumulative mortality in the first three
weeks of 5.9 percent (APHIS, 1994c). In 1996, the proportion of calves born during January through May of 1996
was 78.6 percent. Producers reported a 92.6 percent calving rate (APHIS, 1997a).
In 1992, the average calf weaning weight was 502.4 pounds (APHIS, 1994b). In 1996, the average weaning weights
for steers/bulls and heifers were 526 and 484 pounds, respectively (APHIS, 1998a). Larger operations tend to wean
calves at an older age and heavier weight. Most operations (93.6 percent) wean bulls and steer calves after they
weigh at least 400 pounds, while nearly one-fourth (24.5 percent) wean bulls and steer calves at weights over 600
pounds. On average calves are weaned at 221 days with 77.3 percent of operations weaning calves between 170 and
259 days (APHIS, 1997a). If the cow-calf phase is confined, calves are typically raised in hutches for approximately
12 weeks and then sent to a corral for maturation for an additional 22 to 26 weeks. If calves are intended for veal,
they are sent to slaughter at maturation; if not, the calves are confined for finishing and slaughter. Of the cattle or
weaned calves that are sold, most (85.7 percent) are intended for slaughter (see Table 4-1). The operation average
sale weights are presented in Table 4-2.
Table 4-1. Percent of beef cattle or weaned calves sold in 1996 by
animal class and herd size.
Herd Size, Number of Cows
Fewer
300 or
All
Animal Class
than 50
50-99
100-299
More
Operations
Steers
39.5
46.0
44.6
46.9
43.8
Heifers intended for breeding
10.8
9.3
8.5
6.5
9.0
Heifers intended for slaughter
23.5
29.2
29.9
30.0
27.8
Cows intended for breeding
5.0
1.3
4.9
2.6
3.9
Cows intended for slaughter
14.1
9.7
8.6
11.2
10.9
Bulls intended for breeding
1.5
1.8
1.2
1.2
1.4
Bulls intended for slaughter
5.6
2.7
2.3
1.6
3.2
Source: APHIS, 1997a.
Heifers not confined for finishing are bred and are sent back to pasture or range. Tables 4-3 and 4-4 present the
percentage of operations by type of grazing used, herd size, and location. After a year-long gestation period, bred
cattle calve and either are sent back to pasture or range to be rebred or sent to slaughter. Of the breeding age females
culled in 1992, the most common reasons for culling were pregnancy status (open or aborted) (32.7 percent), age/bad
teeth (21.4 percent), and economics (drought, market, herd reduction) (15.2 percent) (APHIS,
4-1
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Table 4-2. Operation average sale weight for beef cattle and weaned calves
sold in 1996 by animal class and herd size.
Herd Size, Number of Cows
Fewer than
300 or
Animal Class
50
50-99
100-299
More
Steers
584
645
660
674
Heifers intended for breeding
519
600
603
685
Heifers intended for slaughter
557
611
625
689
Cows intended for breeding
1,023
1,058
1,071
1,147
Cows intended for slaughter
996
1,055
1,055
1,073
Bulls intended for breeding
1,145
1,141
1,305
1,239
Bulls intended for slaughter
1,040
1,476
1,600
1,670
Source: APHIS, 1997a.
Table 4-3. Percent of cow-calf operations in 1996 by type of grazing used and herd size.
Type of Grazing
Herd Size, Number of Cows
Fewer than 50
50-99
100-299
300 or More
Grazed on public lands
1.4
6.5
18.0
36.4
Grazed in a grazing association
0.1
1.6
4.7
11.0
Grazed on leased, private land
30.6
49.1
68.0
68.0
Grazed on own land
95.8
96.1
97.3
95.5
Source: APHIS, 1998a.
Table 4-4. Percent of cow-calf operations in 1996 by type of grazing used and state.
Type of Grazing
State
California
Colorado
Montana
New Mexico
Oregon
Wyoming
Kansas
Nebraska
North Dakota
South Dakota
Oklahoma
Texas
Arkansas
Illinois
Iowa
Missouri
Alabama
Florida
Georgia
Kentucky
Mississippi
Tennessee
Virginia
Grazed on public lands
32.8
9.7
0.1
0.0
1.1
Grazed in a grazing association
7.1
2.7
0.1
0.0
0.0
Grazed on leased, private land
49.8
63.0
41.0
45.3
16.1
Grazed on own land
85.4
98.8
94.1
98.4
98.2
Source: APHIS, 1998a.
1994d). Most cow herds have access to pasture, ranging from 83.2 percent in January to 99.4 percent in July.
During the winter months (November-January) 18 to 19 percent of the operations with cow herds had access to crop
residues (APHIS, 1994d). Despite the high proportion of cow-calf operations that use pasture, a large number of
operations also provide hay, silage, supplements, or grain depending on the season (see Table 4-5).
4-2
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Table 4-5. Percent of cow-calf operations feeding hay, silage, supplements, or grain to the
cow herd during 1993. (Value in parentheses corresponds to average pounds of feed per
head per day for operations feeding the associated feedstuff.)
Month
Type of Additional Feed/Supplement
Hay
Silage
Supplements
Grain
January
95.6 (28.4)
3.5 (25.3)
53.1 (1.9)
40.0 (3.4)
March
88.1 (27.0)
3.6 (26.3)
50.2(1.7)
34.9(3.8)
May
14.9(19.7)
0.9 (28.2)
24.9(1.2)
8.1 (4.1)
July
0.8 (22.3)
0.0(0.0)
18.5 (0.9)
4.1 (4.4)
September
11.8(12.4)
0.4(15.0)
24.0(1.4)
6.4 (3.0)
November
63.9 (22.7)
0.1 (34.4)
42.7(1.6)
22.9 (4.3)
Source: APHIS, 1994d.
Cow-calf operations use a variety of water sources including tanks, troughs, automatic waterers, rivers, streams,
ponds, lakes, and other sources. As shown in Table 4-6, natural sources such as ponds/lakes and rivers/streams,
followed by tanks/troughs, are the dominant water sources for most of the year. Table 4-7 summarizes the manure
disposal methods used in cow-calf operations. Sweeten (1998) notes that in many cases the effect on nutrients of
unconfined cow-calf operations on range or pasture cannot be distinguished from natural or background conditions
although elevated bacteria and sediment would be the most common water quality change.
Table 4-6. Percent of cow-calf operations by water source and month.
Water Source
Month
January
April
July
October
Tank or trough
42.6
36.6
38.2
36.2
Automatic waterer
15.4
13.9
9.9
12.4
River/stream
45.5
47.9
46.6
48.1
Pond/lake
54.7
58.9
62.8
61.9
Other
4.7
3.9
4.6
5.4
Source: APHIS, 1994d.
Table 4-7. Percent of operations and beef cows where various methods
were used to dispose of manure. i
Manure Disposal Method
Operations
Beef Cows
Drag or harrow pastures
43.0
44.2
Hauled and spread onto land used for grazing or forage
production for the operation
25.5
34.1
Hauled and spread onto other land
21.9
25.4
Other
2.5
1.7
No disposal
34.7
32.4
Source: APHIS, 1998a.
4.1.2 Finishing Operations
The finishing phase typically starts when the calves reach 6 months of age or weigh at least 400 pounds, and the
phase can last up to 24 months of age. Typically, the annual average steer weight is from 1,100 to 1,300 pounds at
slaughter while the annual average heifer weight is from 1,100 to 1,200 pounds (NASS, 1998). This phase is
4-3
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conducted in a confined area to control weight gain, feed fiber ratios, feed efficiency, feed costs, and animal health.
In this phase, there is generally between 50 to 200 square feet of feedlot area per head of cattle, with the larger space
allocations associated with unpaved lots or wetter conditions. Beef cows and bulls culled from the breeding stock
are slaughtered at weights up to 1,400 pounds. Unlike grazed land, the runoff from feedlots contains high levels of
nutrients, salts, bacteria, and organic matter (Sweeten, 1998).
From 1989 to 1994 for operations with more than 1,000 head, 38.4 and 42.1 percent of operations instituted a
ground and surface water monitoring program, respectively. Nearly 70 (69.6) percent of these operations also
changed their manure management program. Operations with fewer than 1,000 head instituted or changed these
same actions less (instituted ground water monitoring, 10.1 percent; instituted surface water monitoring, 8.8 percent;
changed manure management, 20.1 percent) (APHIS, 1995a).
In the same survey, nearly all (99.5 percent) operations with fewer than 1,000 head dispose of manure on their own
land while only 88 percent of larger operations use their own land. Larger operations (those with 1,000 or more
head) also give the manure away (23 percent), sell the manure (9.3 percent), pay someone to take the manure (6.6
percent), or dispose of it by some other method (4.1 percent). More than one-third (38 percent) of operations with
more than 1,000 head test the manure nutrient content, while only 7.7 percent of smaller operations test manure for
nutrient content. About 50 (48.6) percent of smaller operations and 70 (69.1) percent of operations with more than
1,000 head test the nutrient content of the soil. Of operations testing soil, only one-third (32.5 percent) of smaller
operations and 62.4 percent of operations with more than 1,000 head use soil testing to determine manure application
rates. Forty-five (44.9) percent of operations with more than 1,000 head, while a little more than one-tenth (10.5
percent) of smaller operations, test ground water. Nearly 95 (94.8) percent of dead animals are sent to a renderer for
disposal, and 4.4 percent of dead animals are buried on the farm (APHIS, 1995a).
4.1.3 Housing and Related Facilities
Housing facilities for beef cattle operations include confined calving facilities, bull pens, artificial insemination
areas, and feedlots (MWPS, 1987), all of which require manure management. As suggested earlier, many operations
do not house their cow-calf operations and most finishing operations use feedlots.
Cow-Calf Feed Yard. Separate feed yards might be provided for mature cows, first calf heifers, bulls, and calves.
Layouts and size vary depending on herd size, feed storage and handling equipment, and soil and drainage
conditions. Lot size also depends on how long the cattle are confined. Up to 1,000 square feet per cow-calf unit is
provided. More area is allocated if cattle are penned year-round; less area is allocated if cattle are grazed. Fence-
line feed bunks are common for herds over 100 head, although mechanical feed bunks can be used for herds up to
500 head.
Calving Facility. Calving facilities are used for observing cows and heifers that are ready to calve and might
require assistance. The building might consist of a shed with stalls in colder areas or an open, wind-protected pen in
mild regions. There might be a loose housing observation area, individual pens ranging in size from 10 by 10 to 12
by 12 feet with three solid sides, and a chute for holding and treating cows. The barn or pen is sized to hold 5 to 10
percent of the herd, or more if the risk of severe weather is high, if several cows or heifers require observation at one
time, or if heat synchronization and artificial insemination practices are used. Bedding is provided, as well as heated
areas for the calves in cold or wet weather. Cows and calves are usually turned out 2 to 3 days after birth.
Bull Pens and Yards. Space is usually provided for one bull per 25 cows or heifers. Bulls are penned either
separately or in groups of up to 10 to prevent fighting. Bulls can be kept outdoors if windbreaks and shade are
provided, but a barn is usually available if extreme temperatures occur since such conditions adversely affect bull
fertility.
Open Feedlots. Open feedlots can be paved, partially paved, or unpaved. Feedlots are sloped or graded from 4 to 6
percent to promote drainage away from the lot, typically to a retention pond. Inside the feedlot, mounds provide
4-4
-------
consistently dry areas for cattle to rest. Windbreaks and shade are provided in areas where weather can be extreme.
Alleys for cattle are typically 12 feet wide. In areas of high rainfall or snowfall, more space is needed for drainage
and/or snow storage. Heavily trafficked areas might be paved for easier cleaning and to prevent excessive erosion,
especially near feedbunks and waterers. Table 4-8 presents typical space allocations based on lot slope. Runoff
from feedlots is directed to retention ponds. In some feedlots, a solids separator (i.e., settling pond or sediment trap)
is used as a pretreatment to a retention pond.
Table 4-8. Minimum lot space requirements for different lot slopes.
Slope of Feedlot
Minimum Area Requirement (ft2/head)
4% or greater
150-250
2%-4%
250-400
Less than 2%
400-800
Source: MWPS, 1987.
Cattle Feeding Facility. Outdoor feedlots might have several pens with fence-line feed bunks located around a
central office and feed storage area. Pens have rounded corners to facilitate cattle and equipment turning. The
feedlot area depends on herd size, manure and snow storage, amount of paved area, soil type, drainage, rainfall,
freezing and thawing cycles, and the type of equipment used, although in general lots contain 400 to 450 square feet
per head.
Barn with Outdoor Pens. Semienclosed lots with three-sided barns are used in areas with severe weather or high
rainfall, with outdoor space provided for exercise, resting, and manure storage. Feed, cattle, and equipment stay dry,
promoting more regular feed intake and improved cattle comfort. The barn is designed to improve conditions within;
for instance, a light-colored roof and northern exposure might be used in hot climates to keep the inside cooler, or a
southern exposure and dark-colored roof might be used where heating is needed in colder climates. The floor is
sloped toward the opening, heavily trafficked areas are paved, and bedding might be provided for a loafing area.
Confinement Feeding Barns. Confined feeding barns require less area per head and prevent problems associated
with severe weather and high precipitation. Fence-line or mechanical bunks are used for feeding. Minimum space
allocation is 18 ft2/head in slotted floor pens and 30 ft2/head in solid floor pens for 800- to 1,000-pound cattle.
Slotted floors have the added advantages of easier manure collection and improved cattle cleanliness since cattle
traffic works manure through the slots. Slats are typically concrete, but wood, plastic, and aluminum are also used.
Slot spacing depends on cattle size.
4.2 National Distribution by Type and Size
Table 4-9 summarizes number of cattle and calves from 1989 through 1998. Although the number of milk cows has
declined during this period, the number of beef cows has remained generally stable. Table 4-10 presents the number
of operations in each region by operation size class computed from the 1992 Census of Agriculture. In 1992, more
than one-third of all operations were located in the North-Central Region and more than 20 percent in the Southeast
and South-Central Regions. Figure 4-1 presents a geographic distribution of the number of beef cows per county,
and Figure 4-2 presents the geographic distribution of operations with 500 or more beef cows. Table 4-11
summarizes the number of operations by beef cow herd size by state for 1996 and 1997. Table 4-12 presents the
number of cattle and calves on feed by states for 1996 through 1998.
4-5
-------
Table 4-9. Number of cattle and calves by class and year in the United States.
Year
All Cattle
and
Calves
(thousands)3
Cows and Heifers
that Have Calved
(thousands)
500 Pounds and Over (thousands)
Calves
Under 500
Pounds
(thousands)
Heifers
Steers
Bulls
Beef Cows
Milk
Cows
Beef Cow
Replace.
Milk Cow
Replace.
Other
1989
96,740
32,488
10,138
5,325
4,117
7,631
15,431
2,150
19,461
1990
95,816
32,455
10,015
5,283
4,171
7,803
15,512
2,160
18,418
1991
96,393
32,520
9,966
5,443
4,093
8,102
15,967
2,196
18,107
1992
97,556
33,007
9,728
5,643
4,131
8,048
16,424
2,239
18,336
1993
99,176
33,365
9,658
6,092
4,176
8,550
16,940
2,278
18,118
1994
100,988
34,650
9,528
6,365
4,144
9,068
17,042
2,307
17,884
1995
102,755
35,156
9,487
6,475
4,141
9,275
17,463
2,390
18,369
1996
103,487
35,228
9,416
6,179
4,104
9,949
17,732
2,392
18,488
1997
101,460
34,271
9,309
6,056
4,057
10,199
17,320
2,339
17,909
1998b
99,501
33,683
9.191
5.745
3,982
10,018
17,197
2,266
17,418
" Total may not add due to rounding. b Preliminary.
Source: NASS, 1998.
Table 4-10. Size distribution of all beef operations derived from data collected
in the 1992 Census of Agriculture.
Operations Categorized by Size
Class (animal units3)
500-
1,000-
5,000-
10,000 or
Location
1-25
25-100
100-300
300-500
1,000
5,000
10,000
More
Total
Northeast
56,254
11,825
1,142
125
41
20
0
0
69,407
(9.2%)
(3.8%)
(1.5%)
(1%)
(0.5%)
(0.5%)
(0.0%)
(0.0%)
(6.7%)
Southeast
155,861
70,644
10,220
1,156
569
255
12
5
238,722
(25.4%)
(22.5%)
(13.2%)
(8.9%)
(7.3%)
(7%)
(4.7%)
(2.1%)
(23.2%)
North-Central
216,941
124,906
32,396
4,691
2,538
1,180
97
92
382,841
(35.4%)
(39.8%)
(41.9%)
36.1%)
(32.8%)
(32.2%)
(37.9%)
(38.3%)
(37.2%)
South-Central
125,038
75,539
17,446
2,964
1,857
942
61
80
223,927
(20.4%)
(24%)
(22.6%)
(22.8%)
(24%)
(25.7%)
(23.8%)
(33.3%)
(21.8%)
Mountain
27,385
20,739
11,777
3,045
2,007
905
56
39
65,953
(4.5%)
(6.6%)
(15.2%)
(23.5%)
(25.9%)
(24.7%)
(21.9%)
(16.3%)
(6.4%)
West
30,382
10,295
4,189
988
724
340
30
23
46,971
(5%)
(3.3%)
(5.4%)
(7.6%)
(9.3%)
(9.3%)
(11.7%)
(9.6%)
(4.6%)
Other
597
177
69
13
13
23
0
1
893
(0.1%)
(0.1%)
(0.1%)
(0.1%)
(0.2%)
(0.6%)
(0.0%)
(0.4%)
(0.1%)
United States
612,458
314,125
77,239
12,982
7,749
3,665
256
240
1028,714
a The procedure for estimating animal units was adopted from Lander et al. (1998).
4-6
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Table 4-11. Number of operations by beef cow size group in selected states and United States, 1996-97.a
State
1-49 Head
50-99 Head
100-499 Head
More than 500 Head
1996
1997
1996
1997
1996
1997
1996
1997
AL
27,000
23,000
3,200
3,200
1,750
1,750
50
50
AZ
1,500
1,500
330
230
400
500
170
170
AR
20,000
20,000
4,100
4,100
1,870
1,870
30
30
CA
11,700
11,600
1,200
1,200
1,800
1,700
300
300
CO
5,300
5,300
1,500
1,600
2,450
2,350
250
250
FL
15,300
16,400
1,700
1,600
1,650
1,700
350
300
GA
21,000
20,500
2,800
2,280
1,180
1,200
20
20
ID
5,000
5,100
1,100
1,000
1,280
1,280
120
120
IL
15,600
15,700
1,600
1,600
600
500
IN
15,000
15,000
800
800
200
200
IA
21,000
20,800
5,050
5,250
1,900
1,900
50
50
KS
20,000
19,000
5,900
5,500
3,980
4,350
120
150
KY
38,500
38,000
4,700
4,400
1,770
1,570
30
30
LA
13,400
13,200
1,700
1,600
1,400
1,400
100
100
MN
13,500
13,400
2,000
2,100
480
480
20
20
MS
25,000
24,000
3,000
3,000
960
950
40
50
MO
51,000
48,000
8,000
8,300
3,900
3,600
100
100
MT
4,300
4,800
2,650
2,150
4,200
4,300
550
550
NE
12,300
12,200
4,600
4,600
4,600
4,700
500
500
NM
3,900
3,900
1,000
1,000
1,300
1,300
300
300
ND
5,700
5,300
3,500
3,500
3,140
3,240
60
60
OH
20,000
19,000
780
760
220
240
OK
41,000
42,000
8,400
8,000
4,400
3,800
200
200
OR
14,000
12,000
1,300
1,500
1,300
1,300
200
200
PA
11,500
11,000
380
380
120
120
SD
8,200
7,200
4,500
4,500
5,000
5,000
300
300
TN
46,000
45,000
4,600
3,600
1,375
1,375
25
25
TX
104,000
104,000
17,500
17,500
10,500
10,500
1,000
1,000
UT
3,400
3,200
790
870
890
910
120
120
VA
22,000
23,000
2,800
2,700
1,170
1,260
30
40
WA
11,500
11,500
700
700
750
750
50
50
WY
1,800
1,700
1,000
1,000
1,800
1,800
300
400
Other
87,000
87,000
4,300
4,300
930
950
150
150
US
716,400
703,300
107,480
104,820
69,265
68,845
5,535
5,635
"An operation is any place having one or more cattle on hand during the year. Missing data combined with other size groups.
Source: NASS, 1998.
4-11
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Table 4-12. Cattle and calves: total number on feed by state, 1996-98.a
1996
1997
1998
State
(thousands)
(thousands)
(thousands)
Alabama
5
5
4
Arizona
222
233
245
Arkansas
18
19
10
California
350
375
400
Colorado
1,070
1,130
1,140
Georgia
10
5
5
Idaho
270
270
295
Illinois
290
265
240
Indiana
200
220
170
Iowa
900
1,000
1,000
Kansas
2,210
2,220
2,370
Kentucky
25
20
20
Louisiana
3
3
1
Maryland
17
11
15
Michigan
200
200
200
Minnesota
335
300
275
Mississippi
4
4
3
Missouri
100
95
110
Montana
105
85
80
Nebraska
2,030
2,220
2,300
Nevada
22
25
24
New Jersey
4
6
4
New Mexico
136
137
123
New York
30
30
30
North Carolina
10
10
10
North Dakota
75
100
70
Ohio
235
200
165
Oklahoma
415
400
435
Oregon
80
80
60
Pennsylvania
75
75
75
South Carolina
8
6
7
South Dakota
330
320
320
Tennessee
20
20
20
Texas
2,630
2,630
2,860
Utah
60
50
40
Virginia
35
30
30
Washington
166
163
200
West Virginia
9
8
10
Wisconsin
150
150
155
Wyoming
95
80
85
Other
19
16
12
US
12,968
13,216
13,618
battle and calves on feed are animals for slaughter market being fed a full ration of grain or other
concentrates and are expected to produce a carcass that will grade Select or better.
Source: NASS, 1998.
4-12
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4.3
Waste Management Technologies
Manure management is important in beef cattle facilities to
c Maintain good animal health
c Minimize pollution
c Maintain aesthetics
c Reduce odors and dust
c Control insects and pathogens
c Balance nutrient use
A manure management plan should consider methods for integrating collection, storage, transfer, and use.
One key aspect of designing a manure management plan is the manure consistency. In beef cattle operations, manure
as excreted is semisolid with about 12 percent solids by weight. The advantages of solid handling are reduced total
volume. Labor requirements may be greater in solid waste handling operations since waste handling cannot be easily
automated. Liquid waste handling can be automated, requiring less labor, but equipment installation and
maintenance costs are higher and the total volume of manure is higher due to water inputs. Operator preference is
often the deciding factor in selecting which kind of system will be used. Figure 4-3 provides a schematic of waste
handling alternatives for beef cattle management. The following section describes waste management technologies
for both solid and liquid manure.
4.3.1 Waste Reduction
Waste storage volume can be reduced by diverting clean water (precipitation and surface flow) from contact with
manure. Roofing animal housing areas and manure storage sites (with gutters to divert roof runoff) can be used to
prevent contact with precipitation, while diversionary structures (berms), channels, and well-planned drainage
patterns will keep clean surface runoff out of feedlot and waste storage and treatment areas.
SOLID HANDLING
LIQUID HANDLING
HOUSING
FACILITY
Enclosed Building, Partial Housing,
Paved Open Lots (with bedding), and
Dry Lots (in arid regions)
Enclosed building with slotted floor
Paved open lot (no bedding)
STORAGE
TRANSPORT
UTILIZATION
r
f
r
COLLECTION
Tractor Scrape
Scrape (tractor or
cable)
Slotted
Floor
Flush Alley
Gutter
Under Slats
Liquid/
Solid
Separation
Stockpiled Inside Dry Lots
Stockpiled Outside Dry Lots
Plank walls (roofed)
Concrete Slab (roofed)
Earthen Basin
Concrete Pit or
Tank
Steel Tank
Concrete
Pit
Box Spreader (end gate)
Flail Spreader
Agitate
Tank Wagon
i
Earthen
Plank Wall
Basin or
Concrete
Lagoon
Slab
I
Irrigation
System
Box Spreader
Flail Spreader
Field Spread on Cropland
Figure 4-3. Handling alternatives for beef cattle manure (Source: After Veenhuizen et al., 1992).
4-13
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Nutritional strategies are sometimes used for other livestock, such as swine or poultry, to reduce the nutrient content
of manure. Although some research has been conducted to determine the relationship between feed quality and
waste quantity and quality (Tamminga, 1996), this option has not been adequately reported in the literature at this
time despite anecdotal evidence suggesting opportunities for decreased nutrient excretion.
4.3.2 Waste Collection, Storage, Treatment, and Use
4.3.2.1 Waste Collection
Scraping. Manure scraping is the most common method for collecting solid and semisolid manure from both barns
and open lots. Collection can be done with tractors or mechanical systems. To scrape alleys, tractors can be fitted
with a rubber or steel blade attached to the front or rear. Alternatively, a skid-steer tractor with a front-mounted
bucket can be used to scrape alleys, large open areas, and convoluted spaces. Tractors have fewer problems than
more mechanized systems and work better on frozen manure. Paving surfaces allow for improved scraping, although
unpaved lots can be scraped if care is taken not to disrupt the natural surface seal formed by cattle traffic and
microbial activity (this seal improves surface flow and helps protect against groundwater contamination).
Mechanical scrapers and barn cleaners can reduce labor requirements by automating the scraping process. Also,
odor is reduced in enclosed areas by removing manure regularly (at least once a day). This equipment is limited to a
single alley or gutter and is propelled electrically with cables or chains. Sometimes a single system can clean two
parallel alleys in opposite directions. Alley scrapers are most often used in free stall barns and cover the entire
length and width of the alley in one pass. The cable/chain is recessed into the floor to stabilize the blade and prevent
a tripping hazard. They travel at 4 to 7 feet per minute and do not interfere with cattle in the alley or at the feedbunk.
They can be equipped with automatic stopping systems if an animal or other obstruction gets caught and requires
attention. Cold barns may need to be tractor scraped on very cold days.
Slotted Flooring. This method rapidly removes manure from the animal's space. Cattle traffic works the manure
between the slats and keeps the floor surface relatively clean. Wide slats (4 to 8 inches) are recommended for beef
cattle with spacing between slats of 1.5 to 1.75 inches. Slotted floors should not be used for breeding areas to ensure
firm footing (stressed animals do not breed as well). Slats can be made of concrete, aluminum, or plastic. Each
material has advantages and disadvantages with respect to cost, durability, and animal safety. Concrete is used most
often in beef operations to support the weight of the large animals. Slats should have a textured surface for sure
footing and tapered sides for improved cleaning. Solid manure can be removed from under the floor using
mechanical scrapers or flushing systems.
Flushing systems. Beef cattle manure can be diluted with water to allow for automated handling. However, this
approach increases the volume of manure to be handled, treated, and stored and requires a larger capital investment
for equipment and storage facilities. A flushing system requires a large volume of water to carry manure down a
sloped gutter (0.5 to 1.0 percent) to storage. This system is usually found under slotted floors in beef operations.
Water can be discharged using a flush tank or a large-capacity pump. A small pump can be used to fill the flush
tank. Typically 100 gallons per 1,000 pounds live weight per day is required for adequate cleaning. Large-capacity
pumps are controlled by a time clock. Gutters should be pumped with 110 gpm/foot of gutter width for 3 to 5
minutes at least twice a day.
Liquid can be transferred to a storage lagoon or basin via a sump and pump at the end of collection gutters or with
gravity transfer at a 1 to 5 percent slope through concrete, steel, or plastic pipes. Both systems are flushed with
water to prevent clogging with solids, salts, or mineral deposits. Either clean water or recycled water from a lagoon,
storage basin, or holding pond can be used. Pipe size, flushing frequency, and flush water volume are designed for a
specific consistency and volume of manure to ensure that efficient scouring is achieved. In general, large diameter
(20- to 36-inch) pipes work for manure with up to 3 lb/day of well-mixed, chopped, or fine bedding per 1,000-lb
animal. Small (6- to 8-inch) pipes work well with liquid manure. There should be a 4- to 6-foot difference between
the collection channel and the top of the storage, and the storage should be bottom-loaded to prevent gases from
returning to the building.
4-14
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Runoff from open feedlots, manure storage areas, and feeding facilities are another source of liquid wastes produced
in beef cattle operations. Liquid wastes are directed toward a storage or treatment system. Runoff that has not come
into contact with manure is normally diverted from the storage or treatment system. The size of a treatment system is
dependent on the lot size; the rainfall duration, intensity, and frequency; and the quantity of manure on the lot. The
last is determined based on the number of cattle present, the amount of time during which they have access to the lot,
and the volume of manure produced per animal.
Separation. Runoff or liquid from flushing systems will contain suspended solids that can be removed before
storage in a pond or lagoon or treatment in a vegetated filter area. Separation of liquids and solids reduces the solids
entering a storage facility and extends its storage capacity. For example, a settling basin slows water velocity and
removes solids by gravity (up to 50 to 85 percent removal) if detention time is at least 30 minutes. Baffles and
porous dams can be used to slow the flow, and concrete basins tend to improve solids removal, although in arid
regions where evaporation is high, earthen basins are used. The settling basin needs to be cleared of solids between
runoff events. The solids from separation are cheaper to transport. Choosing a separation system is usually based on
consideration of maintenance, operating, and installation costs; applicability; and benefits that may offset costs.
Common methods to separate liquids and solids include the following:
c Settling basin—gravity separation (see above).
c Centrifuge—rapidly rotating devices that use centrifugal force to squeeze liquids from solids,
c Particle size screens, vibratory screens, strainers, and filters—liquids pass through screen.
c Belt pressure rollers—liquids pass through or out the belts while solids are scraped out.
c Screw presses—liquids pass through a screen while solids are discharged out the end of a cylinder that contains
a screw that conveys the manure,
c Evaporation—common in arid regions where evaporation exceeds precipitation.
4.3.2.2 Waste Storage
Manure, if dry enough, can be stacked as a solid for storage. Storage areas can be located in the barn with the
animals, in a separate, roofed structure, in an unroofed structure, in the feedlot, in a storage yard near the animal
facility, or at the site of future land application (which would require more frequent or daily hauling). If the storage
area is unroofed and precipitation can enter, runoff from the manure area can be collected and treated. Roofed
structures keep out precipitation, and diversionary measures can be used to reduce surface runoff. Solids from
settling ponds or other separation processes would generally be stored in a similar fashion.
Liquid wastes are typically stored in a waste storage pond or in some cases, a reception pit after separation. These
storage structures are rectangular or circular and can be earthen, steel, or reinforced concrete. Belowground storage
tanks are designed based on bedrock depth, water table elevation, and effective pump lift. Tanks made of concrete
are designed to withstand internal and external pressures and potential uplift. Before use, 6 to 12 inches of water is
added to tanks to keep solids submerged. Earthen storage basins can be lined with clay or a synthetic liner (in some
cases both) to prevent leakage to ground water. The choice of liners depends on local regulations, soil and geologic
conditions, cost, and pond emptying methods (for example, some agitation and pumping devices may tear plastics
and geomembranes). In some cases clay liners are susceptible to channeling (macropores) and worm activity.
Runoff that has not passed through areas with manure is excluded to reduce total storage requirements. Currently,
design documents recommend that storage capacities accommodate the runoff from a 25-year, 24-hour storm event
in addition to storing wastewater for a desired length of time and allowing for a 1-foot freeboard. Depending on
climate and other agronomic issues, systems are designed for up to 10 to 12 months of storage (less in warmer
climates), including dilution water from spilled waterers, precipitation, and water added to allow for irrigation of
manure with pumps. Some storage basins are bottom loaded to promote crust formation that reduces odors and fly
problems and to promote even distribution of solids. For bottom-loaded basins, the inlet pipe is at least 1 foot above
4-15
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the bottom of the basin. Aboveground storage tanks are expensive but may be desirable when earthen or pit storage
is unacceptable due to poor geologic, hydrologic, or soil conditions or when alternative storage structures are not
aesthetically acceptable. Aboveground tank sizes range from 10 to 60 feet in height and 30 to 120 feet in diameter.
The tanks are constructed of concrete and steel.
4.3.2.3 Waste Treatment
Composting. Composting produces an excellent soil conditioner that improves organic matter content, soil tilth, and
nutrient content and protects against cropland erosion. Composted manure contains about one-half the nitrogen of
fresh manure; however, much of the nitrogen is in an organic form that is less susceptible to leaching and
volatilization. In fact, only about 15 percent of the nitrogen in manure is available in the first cropping season.
Nevertheless, if manure handling and application methods are inefficient in conserving nitrogen, compost might have
more nitrogen than the field-applied manure. Composting can be labor-intensive and expensive. (Starting costs
range from $20,000 to $125,000 and higher depending on operation size and technology chosen.) Some additives
may be required (i.e., crop residues, sawdust, newspaper clippings, or yard waste) to adjust the carbon-to-nitrogen
ratio and moisture content of the materials. The compost product can be sold to nurseries or cash crop farms to
partially offset treatment costs. Runoff from the composting process should be diverted to retention basins, ground
water infiltration should be minimized, and clean surface runoff should be excluded from treatment areas.
Management practices vary seasonally, but composting can continue year-round even in cold climates.
Table 4-13 presents comparative costs (1994 dollars) of composting. Some compost piles are turned or aerated
regularly to maintain optimal oxygen concentration and temperature. Other composting systems are mechanized and
do not require turning, but capital investment and maintenance costs are higher. Windrow composting involves
placing the manure mixture in long, narrow piles (windrows) that are turned on a regular basis. The windrows are
approximately 3 feet high and 10 to 20 feet wide for dense manure. The shape of the windrow depends on the
turning equipment used. The turning frequency depends on compost materials and climatic conditions. Passively
aerated windrows eliminate the need for turning because air is supplied through open-ended, perforated PVC pipes
embedded in the windrow. Air flow is maintained through two rows of 0.5-inch holes to control the heat produced
by the decomposition process. Windrow materials should be thoroughly mixed when constructed and built on a base
of straw, moss, or compost to absorb moisture and provide insulation. Aerated static piles are similar to passively
aerated windrows, except that air is forced into the pile using pipes with blowers. This method allows for larger piles
and turning is not required. In in-vessel composting, composting materials are confined within a building, container,
or vessel. Forced aeration and mechanical turning techniques are used to speed the process (Minnesota Dept. of
Agriculture, 1995).
Table 4-13. Comparative costs (1994 dollars) of composting methods.
Method
Estimated Cost per Ton
of Incoming Material
Windrow composting using a loader for turning
$5-$10
Windrow composting using specialized windrow turners
$15-$30
Aerated static pile systems
$20-$50
In-vessel systems
$50-$100
Source: Minnesota Dept. of Agriculture, 1995.
Anaerobic Digestion. This process, appropriate for liquid manure, decomposes organic material in the absence of
air. Both methane and carbon dioxide are given off. Collectively, they are referred to as biogas. Biogas, when
collected, can be used as an energy source. The systems best suited for cattle manure include
c Anaerobic lagoon—covers for biogas recovery are considered expensive; biogas yields are low
c Plug-flow system—single tank system; relatively simple to operate; higher potential for loss of treatment
c Complete-mix systems—single tank with mixing systems to evenly distribute solids and increase surface area for
bacterial activity; lower potential for loss of treatment; energy requirements may be high
4-16
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Costs associated with these systems include materials handling, tank covers, heating and mixing equipment, gas
handling equipment, and electricity generation. Odors can be a problem with poorly managed systems.
Aerobic Lagoons and Oxidation Ditches. These systems, also appropriate for liquid manure, allow both aerobic
and anaerobic treatment in the same unit by physical aeration (by movement) in part of the ditch. Treatment
effectiveness is determined by the treatment surface area and the oxygen provided by mixing equipment (or other
supplemental oxygen source) based on daily BOD5 loading per unit. These systems often rely on large surface areas
or high equipment/energy costs to provide oxygen, resulting in the technology's not being cost-effective.
Vegetated Filter Strips and Infiltration Areas. Solids are removed before liquids are treated through a vegetated
filter area since sediment would quickly overload the system. These systems work best for small quantities of runoff
(relatively infrequent or low-intensity runoff events) since continuous application nullifies the ability of the filter
strip to take up nutrients. The inflow is spread out using a concrete apron and a gravel spreader strip. This allows
for further deposition of suspended solids and spreads the water evenly and thinly over the vegetated area. When the
nutrient-rich water enters the soil, it is converted biologically and chemically to plant-available nutrients that are
incorporated into the organic component of the soil or are taken up by plants. This transforms the nutrients into
biomass that can be harvested. Vegetation generally consists of grasses, such as reed canary grass, smooth
bromegrass, and intermediate wheat used alone or in combination with bunch grasses. Species that tend to mat are
usually avoided. Capital investment includes land, surface shaping, and vegetation establishment costs. Periodic
harvesting or mowing is required. Gravel spreaders are replaced every 5 to 10 years to remove solids buildup.
Flow-through time should be at least 15 minutes. The size of the vegetated area depends on feedlot size, slope, soil
type, and rainfall.
4.3.2.4 Waste Use
Land Application. Solid manure can be loaded into manure spreaders (box- or flail-type), dump trucks,
earthmovers, or wagons for broadcast land application as fertilizer or soil conditioner. To minimize nitrogen losses,
solid manure is incorporated soon after application.
Feedlot runoff can be used to water crops, especially if the pond is located near the fields. Using appropriate design
and management, water can be applied with minimal seepage to ground water. Storage capacity should account for
climate (long enough to save up for the growing season). Since the water is nutrient-rich, applying it to crops will
reduce the need for commercial fertilizer. Land application can be accomplished with tank sprayers or piped through
irrigation systems if fields are near the storage site.
Spray or furrow irrigation systems can be used to transport liquids short distances to nearby fields for land
application. High concentrations of solids may clog pumps, pipes, and sprinkler heads in these systems, so solids
separation and/or dilution may be required (however, dilution increases the total volume and treatment
requirements). Initial installation costs are high and equipment will require maintenance, but labor costs can be
greatly reduced with the increased automation.
Depending on the operator, the sludge in the bottom of a lagoon can be removed using an excavator or agitated to
mix with the supernatant. Agitation can be achieved by reversing the flow of the manure pump to facilitate
horizontal and vertical mixing, ensuring not to damage the storage liner. Semisolid manure can be injected into the
ground to reduce odors and nitrogen losses through volatilization.
The timing of liquid application is important to control nutrient losses. Manure should be applied as close to the
time of crop needs as possible, during low rainfall periods, when the ground surface is not frozen, and when soil
moisture is low enough to avoid compaction. In all cases, the rate of manure application can be determined by
balancing crop uptake with existing soil nutrients.
Bedding and Livestock Feed. Dry manure can also be mixed with various bedding materials for loafing barns and
resting areas, or it can be recycled as livestock feed.
4-17
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4.4 Effectiveness of Waste Management Systems
Table 4-14 describes the quantity and nutrient quality of freshly excreted manure. Nutrients are lost in handling and
storage at rates described in Table 4-15. Treatment methods further reduce the nutrient content of manure. The
amounts of nutrients that are ultimately land applied also depend on soil and environmental conditions, as well as the
timing and method of application. Table 4-16 shows that nutrient availability is greater when manure is applied in
the spring, when the soil is finely textured, in areas of low precipitation, and when the manure is incorporated or
injected rather than just surface applied. Land managers therefore have some flexibility in controlling nutrient inputs
from manure to the soil.
Table 4-14. Fresh manure as excreted.
Animal
Size
(lb)
Total Manure Storage Allowance
Nutrient Content of Fresh Manure
N
(lb/day)
P
(lb/day)
K
(lb/day)
lb/day
ft2/day
gal/day
500
30
0.48
3.6
0.17
0.13
0.15
750
45
0.71
5.3
0.26
0.19
0.22
1000
60
0.95
7.1
0.34
0.25
0.30
1250
75
1.19
8.9
0.43
0.31
0.38
Source: MWPS, 1993.
Table 4-15. Nitrogen losses with different handling techniques.
Scrape and Haul
Collection and storage
15-35% losses before application
Broadcasting solids
15-30% during and after application
Additional losses prior to crop use
5-10%
Liquid Handling
Collection and storage
15-35% losses before application
Injection of liquid manure
0-2% losses
Additional losses prior to crop use
5-10% for fall application
Source: Legg and Easter, 1992.
4.5 Example Systems
The goal of this section is to compare and contrast waste management systems from different regions of the country.
This is important because a particular system might be appropriate for one region but entirely ineffective for another.
For example, a lagoon might be suitable for runoff treatment in a humid region where water is plentiful and a 6-foot
depth is easily maintained, whereas in the arid southwest an evaporation or retention pond might be more
appropriate. Some examples are general characterizations of operations in the state or region rather than descriptions
of a specific system.
4.5.1 Ohio (Veenhuizen et al., 1992)
In Ohio, the typical cow/calf beef operation provides housing and bedding during winter and early-spring months.
Solid-manure-handling systems are commonly used with both cow/calf operations and confined feeder operations.
The common housing system for feeder beef cattle is an open-front shelter with an earthen or paved lot. Many
feedlots are unpaved and require more total lot area for effective management. Paved lots are recommended to
reduce the required lot area and ease manure collection and runoff control. Open-lot systems require two
manure-handling methods. Lot scrapings are either solid or semisolid, and lot runoff is liquid. Solid manure is
4-18
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Table 4-16. Estimated N availability (%) as a function of soil properties, environment, and
application time and method for first year after application, assuming that
50% of the applied N is organic N and 50% is inorganic N.
Time of
Application
Soil
Texture
Rainfall
Application Methods
Broadcast w/o
Incorporation
Broadcast w/
Incorporation
Knife Injection
Sweep Injection
Fall
Coarse
Low, Norm
30
55
45
55
High
20
45
40
45
Fine
Low, Norm
35
60
50
60
High
30
55
45
55
Spring
Coarse
Low, Norm
40
55
50
55
High
35
50
45
50
Fine
Low, Norm
45
55
45
55
High
45
55
40
50
Fall
Coarse
Low, Norm
30
35
50
60
High
24
40
40
50
Fine
Low, Norm
35
55
45
55
High
35
50
40
50
Spring
Coarse
Low, Norm
40
50
50
55
High
35
45
45
50
Fine
Low, Norm
40
50
45
55
High
40
50
40
50
Source: Schmitt, 1990.
moved from the lot to storage with a tractor scraper and front-end loader. Lot runoff is collected as part of the
manure-handling system. Clean runoff should be diverted away from manured areas to reduce the total volume of
liquid.
Beef cattle can be fed in solid or slotted-floor confinement buildings. Liquid-manure-handling systems are common
with confinement housing. Manure is stored in a concrete tank under the building or in an outdoor earthen or
concrete storage. It is transferred from the building with either a tractor or mechanical scraper, or by gravity flow.
Manure can be handled as a liquid, semisolid, or solid. The amount of dilution water or bedding influences the
manure's form, but ultimately the choice of a manure handling and storage system is dictated by the landowner's
preference for a more automated liquid system with greater initial costs or a more labor-intensive solid system that
requires less capital investment.
Storage capacity depends on the existing regulations, number and size of animals, quantity of bedding used, amount
of dilution by spilled and cleaning water, amount of stored precipitation and runoff, and desired length of storage.
The required length of storage can vary from farm to farm. Enough storage capacity and length of storage should be
provided to allow spreading of manure when field conditions, weather, and local regulations permit. It is
recommended that 3 to 6 months of storage capacity for liquid manure and at least 3 months of storage capacity for
solid manure be allowed. Storage capacity of up to 12 months will provide more flexibility for scheduling
field-spreading of manure.
4.5.2 Southeast Region (Alabama NRCS, 1998a, 1998b; Brantley, personal communication, 1998; Deal,
personal communication, 1998; and Georgia NRCS, 1997)
Large confined beef cattle facilities are rare in the southeastern United States due to the distance from feed sources
and slaughter houses, adverse cattle-raising conditions (very hot and humid), and problems with excessive runoff due
4-19
-------
to high rainfall rates. Although beef cattle are present in this area, stock density is very low. Often, little manure
management is required unless several animals are confined in a small area where contaminated runoff drains to a
stream or other water body. If this is the case, a filter strip or other instrument of nutrient removal should be
installed between the lot and the water. Solid storage capacity of 30 to 45 days is recommended for a stacking
facility, and at least 90 to 180 days of storage should be allowed for liquids in a holding pond. Storage capacity
should also include precipitation directly into the storage unit, nondiverted runoff generated from the facility's
drainage area during a 25-year, 24-hour precipitation event, and residual solids that are not pumped out when the
liquids have been removed. Wastewater should not be applied within 2 days of a predicted rain or 2 days after a rain
of 0.5 inch or more. The Southeast Regional NRCS office has several documents specifying standards for designing
and operating waste management systems and their components, which can be found at their web site:
http://www.ga.nrcs.usda.gov/reg/cps.html.
4.5.3 Northeast Region (University of Delaware, 1989; Graves, 1986; and Sato, personal communication,
1998)
There are few large feedlots in this area, although there are many smaller beef operations. Manure is considered a
commodity, and nutrient management plans are written to apply the manure agronomically.
Runoff is diverted from manure lots using diversions and roof runoff management (gutters, downspouts, etc.). Lot
runoff that has contacted manure is collected using curbing, grading, pipes, culverts, paving, and other collection
methods. It is stored in holding ponds or storage tanks and is sometimes treated and disposed of using a vegetated
filter strip. Storage capacity is determined by the accumulated runoff volume from the drainage area and rain
volume over the storage structure. The liquids are stored in a holding pond and land applied using spray tankers at
rates dictated by the nutrient management plan. Solids separation is used before the stored runoff is irrigated.
Solid manure can be stored in the same lot if it is under a roof, or it can be hauled to a separate facility. Daily land
application is done when no storage is available. Solid storage capacity is generally designed for approximately 6
months if under a roof. Storage time varies depending on the size of the storage area, the availability of land for
application, and local weather conditions (because manure should not be applied when the ground is frozen or wet).
Solid manure treatment is not common in this region, although some landowners do use solids separation and
composting. Land application is accomplished with manure spreaders prior to planting in spring or after harvest in
fall. If the latter, conservation measures are taken to prevent surface water contamination.
4.5.4 South-Central Region (Green, personal communication, 1998)
This region receives an average of 12 to 16 inches of rain per year. Cattle are kept in open, dry lots, where manure is
frequently scraped and piled within the lot until it is removed as a solid and land applied using a manure spreader.
The frequency of scraping and duration of storage depend on landowner preferences. Runoff control is achieved
using diversions to prevent clean runoff from entering the feedlot, while feedlot runoff is channeled to a storage pond
to be land applied.
Storage pond volume is designed for a minimum of 45 days' storage of solids, liquids, precipitation, and runoff from
a 25-year, 24-hour storm, and a 1-foot freeboard. Solids removal can be achieved with a settling basin or other solid
separation mechanism, or both solids and liquids can be stored in the pond together. Either agitation to produce
slurry for land application or irrigation of water and subsequent scraping and sludge application of solids can
maintain the storage pond's capacity. Treatment lagoons are not practical in this area since it is difficult to maintain
a minimum depth due to high evaporation rates. Treatment to reduce nitrogen is generally not necessary since
manure is used as a crop fertilizer. The NRCS recommends land application from March to November when the
crop is actively growing and when the ground is neither saturated nor snow-covered.
4-20
-------
4.5.5 Colorado (Meyer, personal communication, 1998)
In Colorado, most beef cattle feedlots are located in the arid (approximately 10 inches of rain per year) eastern part
of the state. These account for 85 percent of Colorado's cattle. The other 15 percent are found on smaller farms
throughout the state. These feedlots act as a finishing center for cattle that are owned by smaller farms. When the
finished cattle are returned, their owner is required to haul a quantity of manure from the feedlot in proportion to the
number of cattle that were sent for finishing. This relieves part of the feedlot manager's burden of manure disposal.
At the feedlot, the cattle are penned in large, open lots that are frequently scraped of solids. Little effort is taken to
control runoff since precipitation is low and the large feedlots are not located near waterways. However, berms and
other diversions are used to keep clean runoff from storms from entering the lot. Storage ponds are generally not
used for liquid waste since very little is produced. Evaporation is responsible for eliminating most of the liquid
waste.
For the smaller confined beef operations, solid waste is scraped and stored temporarily until it can be land applied to
crops with a manure spreader. Since Colorado rangeland is not lush with vegetation, manure applications for this
type of land use are less than they would be in an area where more dense vegetation could use most of the nutrients.
There have been limited efforts with windrow composting of solid manure to improve the quality of the manure
materials.
4.6 Bibliography
Alabama NRCS. 1998. Waste Transfer (Conservation Practice Standard Code 634).
Alabama NRCS. 1998. Waste Utilization (Conservation Practice Standard Code 633).
APHIS. 1993. National Animal Health Monitoring System, Parti: Beef Cow/CalfHerd Management Practices in
the United States, . File chapdesl.pdf accessed October 15,
1998. U.S. Department of Agriculture, Animal and Plant Health Inspection Service.
APHIS. 1994a. National Animal Health Monitoring System, Part II: Beef Cow/Calf Reproductive and Nutritional
Management Practices, . File chapdes2.pdf accessed October
15, 1998. U.S. Department of Agriculture, Animal and Plant Health Inspection Service.
APHIS. 1994b. National Animal Health Monitoring System, Part III: Beef Cow/Calf Health Management.
. File chapdes3.pdf accessed October 15, 1998. U.S.
Department of Agriculture, Animal and Plant Health Inspection Service.
APHIS. 1994c. National Animal Health Monitoring System, Part IV: Beef Cow/Calf Breeding Management.
. File chapdes4.pdf accessed October 15, 1998. U.S.
Department of Agriculture, Animal and Plant Health Inspection Service.
APHIS. 1994d. National Animal Health Monitoring System, Part V: Quality Assurance Profile.
. File chapdes5.pdf accessed October 15, 1998. U.S.
Department of Agriculture, Animal and Plant Health Inspection Service.
APHIS. 1995a. National Animal Health Monitoring System, Parti: Feedlot Management Practices.
. Files cofdesla.pdf and cofdeslb.pdf accessed October 15,
1998. U.S. Department of Agriculture, Animal and Plant Health Inspection Service.
APHIS. 1995b. National Animal Health Monitoring System, Part II: Feedlot Health Management Report.
. File cofdes2.pdf accessed October 15, 1998. U.S. Department
of Agriculture, Animal and Plant Health Inspection Service.
4-21
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APHIS. 1997a. National Animal Health Monitoring System, Part I: Reference of1997 Beef Cow-CalfManagement
Practices, . File bf97desl.pdf accessed October 15, 1998. U.S.
Department of Agriculture, Animal and Plant Health Inspection Service.
APHIS. 1997b. National Animal Health Monitoring System, Part II: Reference of1997 Beef Cow-Calf Health and
Health Management Practices, . File bf97des2.pdf accessed
October 15, 1998. U.S. Department of Agriculture, Animal and Plant Health Inspection Service.
APHIS. 1998a. National Animal Health Monitoring System, Part III: Reference of1997 Beef Cow-Calf Production
Management and Disease Control, . File bf97des3.pdf
accessed October 15, 1998. U.S. Department of Agriculture, Animal and Plant Health Inspection Service.
APHIS. 1998b. National Animal Health Monitoring System, PartIV: Changes in the U.S. Beef Cow-Calf Industry,
1993-1997. . File bf97des4.pdf accessed October 15, 1998.
U.S. Department of Agriculture, Animal and Plant Health Inspection Service.
Brantley, Sid, P.E. Regional Grazing Land Coordinator, NRCS. Personal communication. August 31, 1998.
Deal, Pete, P.E. Rangeland Management Specialist, Florida NRCS. Personal communication. August 31, 1998.
Georgia NRCS. 1997. Waste Storage Facility (Conservation Practice Standard Code 313).
Graves, Robert E. 1986. Beef Manure Management: A supplement to Manure Management for Environmental
Protection. Pennsylvania Department of Environmental Resources and Commonwealth of Pennsylvania,
Harrisburg, PA.
Green, John, P.E. Oklahoma NRCS. Personal communication. September 1, 1998.
Lander, C.H., D. Moffitt, and K. Alt. 1998. Nutrients Available from Livestock Manure Relative to Crop Growth
Requirements. U.S. Department of Agriculture, Natural Resources Conservation Service, Resource
Assessment and Strategic Planning Working Paper 98-1. . Accessed October 15, 1998.
Legg, Thomas D. and K. William Easter. 1992. Manure is a Good Source of Nitrogen. Minnesota Extension
Service, University of Minnesota.
Meyer, Daniel, P.E. Colorado NRCS. Personal communication. September 2, 1998.
MWPS, Iowa State University. 1987. Beef Housing and Equipment Handbook, 4th ed.
Minnesota Department of Agriculture. 1995. Manure Management Alternatives: A Supplemental Manual.
NASS. 1998. Agricultural Statistics 1998. . File 98_ch7.pdf
accessed October 19, 1998.
Reichow, Kathy. 1995. Manure Management Planning Guide for Livestock Operators. Minnesota Department of
Agriculture, Agriculture Planning and Development Division.
Sato, Noel. Grazing Lands Specialist, PA-NRCS. Personal communication. September 8, 1998.
Schmidt, Michael A. 1990. Manure Management in Minnesota. Minnesota Extension Service, University of
Minnesota.
4-22
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Sweeten, John M. 1998. Cattle Feedlot Manure and Wastewater Management Practices. In Animal Waste
Utilization: Effective Use of Manure as a Soil Resource, ed. J.L. Hatfield and B.A. Stewart. Ann Arbor
Press, Chelsea, Michigan.
Tamminga, S. 1995. A Review on Environmental Impacts of Nutritional Strategies in Ruminants. Journal of
Animal Science 74: 3112-3120.
University of Delaware. 1989. Beef Manure Management: .1 Supplement to Delaware Guidelines—Manure
Management for Environmental Protection. Agricultural Experiment Station, Cooperative Extension,
Newark, DE.
USDA-NRCS. 1992. Agricultural Waste Management Field Handbook, Chapters 1-11. U.S. Department of
Agriculture, Natural Resources Conservation Service, Washington, DC.
Veenhuizen, Michael A., Donald J. Eckert, Kevin Elder, Jay Johnson, William F. Lyon, Karen M. Mancl, and Gary
Schnitkey. 1992. Ohio Livestock Manure and Wastew ater Management Guide (Bulletin 604).
.
4-23
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5.0 Sheep
5.1 Introduction
The sheep industry declined from approximately 30 million head in 1960 to less than 10 million head by the mid-
1990s. The decrease in real prices for lamb is also resulting in structural changes as farmers diversify into other
enterprises. The seasonality issues of lamb production, imports, and competing pricing of other commodities such as
pork, poultry, and beef also have a major influence on the structure of the industry.
The sheep industry in the United States is diverse. Some operations produce farm flocks of 50 to 200 animals.
Others have very large range operations of 1,000 to 5,000 sheep with shepherds to watch over the sheep and dogs (or
other predator management practices) to guard the sheep from predators. Sheep can adapt to a wide range of
climates and management systems and therefore can be raised all over the country.
In 1995 an average of 121.3 lambs were born alive per 100 ewes exposed. Smaller operations (flock sizes smaller
than 50) had the highest number of lambs born alive with 138 per 100 ewes. There is a trend of fewer live lambs per
ewe in larger operations. Operations with a flock size between 500 and 999 had an average of 121.1 live lambs per
100 ewes, and operations with a flock size of more than 1,000 had an average of 108 live lambs per 100 ewes.
Approximately 9.4 percent of lambs born alive die before weaning. Mature sheep (those 1 year of age or older) are
culled at a rate of 16.1 percent and die due to other causes at an annual rate of 5.1 percent (APHIS, 1996b).
Most sheep are raised in a grazing environment (Table 5-1), with only 2.3 percent of operations in the United States
having intensive confinement, representing 6.4 percent of all sheep raised in that type of operation (APHIS, 1996b).
During the 9-year period from 1988 to 1996, the average live weight of all sheep and lambs ranged from 124 to 128
pounds, with dressed weights of 63 to 64 pounds. During the same period, the number of sheep slaughtered per year
range from 5.72 million in 1991 to 4.18 million in 1996 (NASS, 1998). Table 5-2 shows the percentage of
operations that raise each breed of sheep and the distribution of the different breeds. Fine wool white face sheep are
the most common, making up 41.8 percent of all sheep, but are raised in only 13 percent of sheep operations.
Table 5-1. Percent of operations and percent of shee
Flock Type
Percent Operations
Percent Sheep
Herded range flock
1.0
18.9
Fenced range flock
10.0
37.3
Farm flock
84.9
34.6
Intensive confinement
2.3
6.4
Multiple types
1.8
2.8
) by primary flock type.
Source: APHIS, 1996b.
Feed and forage costs tend to be the single largest cost of producing lamb and wool. The housing and confinement
structures for sheep are not usually very costly. Typically, sheep are placed in either a fenced in or herded area and
can graze freely. Four typical management systems for rearing sheep include the following:
Pastures-a plot of land for grazing; the solid manure can be dispersed, requiring no extra handling if there is
enough land area; rotating land areas and avoiding steep slopes, streams, and drainage ways minimize
runoff pollution. Sheep prefer to graze hillsides and steep slopes and can provide a means for improving
forage utilization and fertility in those areas since they possess a great ability to convert a wide variety of
forage and crop residues into meat and fiber.
5-1
-------
Table 5-2. Percent of operations and percent of sheep
by
primary breed category.
Breed Category
Percent Operations
Percent Sheep
Colored wool
2.4
0.6
Fine wool white face
13.0
41.8
Medium wool white face
20.6
26.0
Black face
32.3
10.2
Crossbred
23.8
15.6
Hair sheep
1.0
0.4
Milk sheep
0.0
0.0
Multiple breeds
6.9
5.4
Total
100.0
100.0
Source: APHIS, 1996a.
Open Lots for Sheep-open lots should be located away from streams, steep slopes; settling basins are
recommended for lot runoff.
Facilities with Slotted Floors-slats or perforated mesh flooring rapidly separates the animal from its manure
improves cleanup, and reduces buildup of solids and the daily labor. Flooring can be made out of wood,
concrete, steel, aluminum, or plastic.
Bedded pens-bedded pens, with a manure pack, are the most common housing for sheep.
5.2 Demographics
5.2.1 National Change and Composition
The U.S. sheep and lamb inventory for 1996 was 8.46 million. Of these animals 60.6 percent are ewes 1 year old or
older, 2.8 percent are rams, 10.2 percent are replacement lambs, and 26.4 percent are market sheep and lambs.
Approximately 11.8 percent of the 82,000 operations with sheep in 1995 are not expected to have sheep in 2001
(APHIS, 1996b).
Table 5-3 summarizes how the sheep and lamb inventory has declined since 1989, when there were a total of 10.853
million head. In 1998, there were 7.616 million head. Table 5-4 summarizes breeding sheep operation size across
the United States during 1997 and 1998. In 1997 there were an estimated 74,710 operations with sheep. More than
90 percent of the operations had fewer than 90 head, representing about one-fourth of the breeding inventory.
Operations with 100 to 499 head represent a little more than 6 percent of the operations and one-fifth of the breeding
inventory. A little more than 2 percent of the operations have more than 500 head and represent about 55 percent of
the breeding inventory (NASS, 1998).
5.2.2 Geographic Distribution
Table 5-5 summarizes number of operations in each region by operation size class using the 1992 Census of
Agriculture. Table 5-6 present the number of breeding and market sheep by state for 1997 and 1998. In 1998 the
states with more than 200,000 breeding sheep and lambs include Texas (1,170,000), Wyoming (510,000), California
(440,000), Montana (385,000), South Dakota (330,000), Utah (315,000), Colorado (240,000), Idaho (234,000), and
New Mexico (215,000). The states with more than 100,000 market sheep and lambs include California (430,000),
Colorado (335,000), Texas (330,000), and Wyoming (170,000). Figure 5-1 presents a geographic distribution of the
number of sheep and lambs per county, and Figure 5-2 presents the geographic distribution of operations with 1,000
or more sheep and lambs. The number of operations with sheep and lambs from 1994 to 1997 is presented in Table
5-7.
5-2
-------
Table 5-3. Sheep inventory and lamb crop (January 1 sheep inventory).
Year
All Sheep
and Lambs
(thousands)
Sheep and
Lambs on
Feed
(thousands)
Breeding Sheep (thousands)
Total
Lambs
1 year and Over
Ewes
Wethers®
and Rams
Ewes
Wethers®
and Rams
1989
10,853
1,646
9,207
1,341
346
7,186
334
1990
11,358
1,762
9,596
1,322
311
7,608
355
1991
11,174
1,730
9,444
1,340
347
7,409
348
1992
10,797
1,832
8,965
1,166
320
7,129
350
1993
10,201
1,896
8,305
1,126
308
6,537
333
1994a
9,742
1,839
7,233
864
384
5,804
302
1995a
8,886
C
6,436
878
d
5,300
258
1996a
8,461
C
6,228
863
d
5,128
236
1997a
7,937
C
5,850
794
d
4,836
220
1998ab
7.616
C
5.537
804
d
4.527
206
a Includes new crop lambs.b Preliminary, discontinued. d Combined with ewes. e Castrated males.
Source: NASS, Livestock and Economics Branch.
Table 5-4. Breeding sheep: survey percent of operations by size group in 1997 and 1998.
Percent of Operations by Size Group
1-99 Head
100-499 Head
500-4,999 Head
5,000 or More Head
1997
1998
1997
1998
1997
1998
1997
1998
91.9
90.8
6.2
6.8
1.8
2.3
0.1
0.1
Percent of Inventory by Size Group
1-99 Head
100-499 Head
500-4,999 Head
5,000 or More Head
1997
1998
1997
1998
1997
1998
1997
1998
25.7
25.5
20.3
19.2
40.0
42.6
14.0
12.7
Source: NASS, 1998.
Table 5-5. Size distribution of all sheep operations derived from data
collected in the 1992 Census of Agriculture.
Location
Operations Categorized by Size Class (animal units3)
1-25
25-100
100-300
300-500
500-
1,000
1,000-
5,000
5,000-
10,000
10,000 or
More
Total
Northeast
9,643
(11.8%)
68
(2.1%)
5
(0.5%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
9,716
(11.3%)
Southeast
5,769
(7%)
46
(1.4%)
6
(0.6%)
0
(0.0%)
1
(1.1%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
5,822
(6.7%)
North Central
38,352
(46.8%)
887
(27.9%)
106
(11.5%)
10
(6.6%)
3
(3.2%)
2
(5.6%)
0
(0.0%)
0
(0.0%)
39,360
(45.6%)
South Central
9,244
(11.3%)
898
(28.2%)
259
(28%)
33
(21.7%)
12
(12.9%)
9
(25%)
0
(0.0%)
0
(0.0%)
10,455
(12.1%)
Mountain
9,991
(12.2%)
982
(30.9%)
458
(49.6%)
78
(51.3%)
51
(54.8%)
20
(55.6%)
1
(100%)
1
(100%)
11,582
(13.4%)
West
8,784
(10.7%)
292
(9.2%)
90
(9.7%)
31
(20.4%)
25
(26.9%)
5
(13.9%)
0
(0.0%)
0
(0.0%)
9,227
(10.7%)
Other
86
(0.1%)
6
(0.2%)
0
(0.0%)
0
(0.0%)
1
(1.1%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
93
(0.1%)
United States
81,869
3.179
924
152
93
36
1
1
86,255
a The procedure for estimating animal units was adopted from Lander et al. (1998).
5-3
-------
Table 5-6. Number of breeding and market sheep and lambs by state during 1997 and 1998.
Breeding Sheep and Lambs
Market Sheei
p and Lambs0
1997
1998"
1997
1998"
State
(thousands)
(thousands)
(thousands)
(thousands)
Alabama
7.0
7.0
a
a
Alaska
1.4
1.3
0.2
0.1
Arizona
50.0
53.0
75.0
67.0
California
480.0
440.0
480.0
430.0
Colorado
250.0
240.0
325.0
335.0
Connecticut
6.2
6.1
0.8
0.9
Idaho
245.0
234.0
40.0
51.0
Illinois
69.0
68.0
10.0
11.0
Indiana
55.0
44.0
12.0
11.0
Iowa
188.0
158.0
97.0
77.0
Kansas
100.0
80.0
50.0
40.0
Kentucky
17.7
14.0
4.3
3.0
Louisiana
13.0
12.0
2.0
1.5
Maine
OO
OO
9.5
1.2
1.5
Maryland
27.6
28.2
4.4
4.8
Massachusetts
10.0
9.9
1.5
1.1
Michigan
65.0
60.0
33.0
30.0
Minnesota
130.0
110.0
50.0
60.0
Missouri
55.0
52.0
13.0
13.0
Montana
400.0
385.0
32.0
25.0
Nebraska
77.0
84.0
18.0
16.0
Nevada
74.0
70.0
11.0
10.0
New Hampshire
5.8
6.1
0.7
0.9
New Jersey
13.5
13.0
4.0
4.0
New Mexico
220.0
215.0
15.0
25.0
New York
48.0
53.0
12.0
12.0
North Carolina
11.5
10.0
1.7
1.0
North Dakota
105.0
84.0
30.0
26.0
Ohio
101.0
87.0
29.0
30.0
Oklahoma
60.0
56.0
15.0
14.0
Oregon
209.0
175.0
95.0
90.0
Pennsylvania
81.0
80.0
13.0
14.0
South Dakota
355.0
330.0
95.0
70.0
Tennessee
10.0
9.0
3.5
2.0
Texas
1,150.0
1,170.0
250.0
330.0
Utah
339.0
315.0
36.0
35.0
Vermont
14.3
11.5
2.1
2.5
Virginia
65.0
64.0
15.0
17.0
Washington
45.0
47.0
5.0
15.0
West Virginia
42.0
35.0
8.0
5.0
Wisconsin
57.0
58.0
12.0
12.0
Wyoming
550.0
510.0
170.0
170.0
Other States
38.1
42.1
14.8
15.0
US
5,849.9
5,536.7
2,087.2
2,079.3
a Data for this table are no longer available.b Preliminary.c Sheep and lambs on feed are animals being fattened for slaughter market on grain,
other concentrates, or succulent pastures and are expected to produce a carcass that will grade Good or better.
Source: NASS, 1998.
-------
Table 5-7. Operations with sheep and lambs (1994-1997).
State
1994
1995
1996
1997
Alabama
340
310
310
300
Alaska
40
40
40
40
Arizona
450
450
400
400
California
5,000
4,800
4,600
4,500
Colorado
1,600
1,300
1,300
1,200
Connecticut
480
350
350
350
Idaho
1,400
1,300
1,100
1,100
Illinois
3,700
3,500
3,300
3,100
Indiana
3,200
2,700
2,400
2,700
Iowa
6,500
6,300
6,000
5,800
Kansas
2,300
1,900
1,900
2,000
Kentucky
1,000
900
850
800
Louisiana
1,100
1,000
900
800
Maine
700
600
550
550
Maryland
1,100
1,000
1,000
1,100
Massachusetts
600
500
500
600
Michigan
2,100
2,000
2,000
2,100
Minnesota
3,600
3,500
3,300
3,000
Missouri
2,900
2,600
2,300
2,100
Montana
2,300
2,200
2,200
2,200
Nebraska
1,700
1,800
2,000
2,000
Nevada
350
350
350
350
New Hampshire
540
400
450
400
New Jersey
900
850
800
800
New Mexico
1,000
1,000
1,000
900
New York
1,800
1,700
1,800
1,700
North Carolina
600
600
600
620
North Dakota
1,400
1,200
1,000
1,000
Ohio
5,200
5,000
4,500
4,000
Oklahoma
2,000
1,700
1,700
1,700
Oregon
3,200
2,600
3,100
3,000
Pennsylvania
3,300
3,200
3,100
3,000
South Dakota
3,500
3,000
2,700
2,500
Tennessee
650
650
650
600
Texas
7,600
7,300
7,000
6,500
Utah
2,000
1,900
1,700
1,600
Vermont
720
750
600
600
Virginia
1,800
1,600
1,400
1,300
Washington
1,500
1,500
1,500
1,500
West Virginia
1,500
1,600
1,400
1,300
Wisconsin
2,500
2,400
2,300
2,100
Wyoming
1,200
1,100
1,100
1,100
Other States
1,780
1,620
1,460
1,400
Total U.S.
87,150
81,070
77,510
74,710
Source: NASS, 1998.
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5.3
Waste Management Technologies
A market lamb weighing about 100 pounds produces about 4 pounds of manure daily. Table 5-8 gives the typical
amount of manure and its constituents provided by 1,000 lb of sheep or lamb per day. In some areas of the country,
sheep are used to graze leftover stalks and seeds after crops have been harvested. Crop residues, grass clippings, and
food processing by-products are often feed to sheep. However, controlling sheep diets from a waste management
perspective has not been considered in the literature at this time.
Table 5-8. Fresh manure production and characteristics
per 1,000 pounds of live animal weight per day from
ASAE Standard D384.1 DEC93.
Parameter
Sheep
Total Manure (lb)
40
Urine (lb)
15
Density (lb/cubic feet)
64
Total solids (lb)
11
Volatile solids (lb)
9.2
BOD5 (lb)
1.2
COD (lb)
11
Total Kjeldahl Nitrogen (lb)
0.42
Total Phosphorus (lb)
0.087
Orthophosphorus (lb)
0.032
Source: ASAE, 1998.
Because of sheep manure's density and moisture content (75 percent water), the manure is almost always handled as
a solid by scraping and hauling to the field. In fact, it is difficult to handle as a liquid because manure solids float
(low density) to the surface. As stated earlier, only 2.3 percent of operations in the United States have intensive
confinement, which represents 6.4 percent of all sheep raised (APHIS, 1996b). As a result, most sheep manure is
dispersed onto pastures and requires no handling. For those operations that confine sheep, most of the waste
management technologies will be similar to those presented for handling solid wastes from beef feedlots. A brief
synopsis is provided here, but the reader is referred to Chapter 4 for further reading.
Open Lot with Shelter. Unpaved lots are scraped periodically and the manure is field spread; paved lots are
scraped regularly, and the manure is field spread either immediately or after storage. Lot runoff is handled using
holding ponds or vegetated infiltration areas to control runoff. Settling basins are recommended between the lot and
holding pond or infiltrated area to remove large manure solids that either float or settle from runoff. The settling
basin floor can be paved to facilitate cleaning. An expanded metal screen and a perforated pipe riser drain runoff
water from settled solids. For most of the United States, 5 to 10 cubic feet of settling basin per 100 square feet of the
lot area is sufficient. Sludge buildup in the pond tends to be greater with unpaved lots, with infrequent lot scraping,
and where settling basins are not used (Hirning et al., 1994).
Vegetated Filter Strips and Infiltration Areas. A vegetated infiltration area is practical for many feedlots up to
about 750 head if located next to grassland or other land kept out of crop production. Infiltration capacity is sharply
reduced unless runoff is passed through a settling basin (Hirning et al., 1994).
Slotted Floors. Slotted floors significantly reduce daily labor for manure handling. Some of the more common
floor materials used are green, undressed oak; concrete; flattened expanded metal X-plate; unflattened, expanded
metal; metal and plastic slats; and kiln-dried pine. Floors and fleeces stay cleaner on more open floors and with
high-roughage diets. Sheep are more sure footed and hooves wear more evenly on expanded metal than on other
materials. Oak floors have irregular openings between slats that can trap lambs' feet. Pine floors soon show heavy
wear. The choice of materials depends on cost, desired life expectancy, labor availability, cleanliness desired, and
slipperiness (Hirning et al., 1994).
5-10
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5.4 Bibliography
American Sheep Industry Association, Inc. 1997. Caring for Land Animals. Sheep Production Handbook.
.
American Sheep Industry Association, Inc. 1997. Management Chapter. Sheep Production Handbook.
.
American Sheep Industry Association, Inc. 1997. Potential Nutritional Problems. Sheep Production Handbook.
.
American Sheep Industry Association, Inc. 1997. Sheep and Waste Management. Sheep Production Handbook.
.
APHIS. 1996a. Reference of1996 U.S. Regional Sheep Health and Management Practices.
. File sheepreg.pdf accessed October 15, 1998. U.S.
Department of Agriculture, Animal and Plant Health Inspection Service.
APHIS. 1996b. Reference of1996 U.S. Sheep Health and Management Practices.
. File sheepnatpdf accessed October 15, 1998. U.S.
Department of Agriculture, Animal and Plant Health Inspection Service.
ASAE. 1998. ASAE Standards 1998. ed. American Society of Agricultural Engineers, St. Joseph, MI.
Chastain, John P. 1995. Pollution Potential of Livestock Manure. University of Minnesota. Department of Animal
Science, .
Hirning, et al. 1994. Sheep Housing and Equipment Handbook. 45th ed. Midwest Planning Service, Agricultural
and Biosystems Engineering Department, Iowa State University, Ames, IA.
Lander, C.H., D. Moffitt, and K. Alt. 1998. Nutrients Available from Livestock Manure Relative to Crop Growth
Requirements. U.S. Department of Agriculture, Natural Resources Conservation Service, Resource
Assessment and Strategic Planning Working Paper 98-1. . Accessed October 15, 1998.
Morse, Deanne. October 1993. Water Quality: The Animal Component. In Water Quality Management.
North Dakota State University.
NASS. 1998. Agricultural Statistics 1998. . File 98_ch7.pdf
accessed October 19, 1998.
Ohio State University Extension. 1992. Ohio Livestock, Manure, and Wastewater Management Guide.
Bulletin 604. .
Palmer, Jack. 1993. Idaho Waste Management Guidelines for Confined Feeding Operations (For Non-Dairy
Facilities). Idaho Department of Health and Welfare. Division of Environmental Quality. Twin Falls, ID.
.
Purdue University. 1996. Sheep Manure Management. Department of Agricultural and Biological Engineering.
Cooperative Extension Service, .
Umberger, Steven H. June 1996. Sheep Production in Virginia. Virginia Cooperative Extension. Publication
#410-025. .
University of California Division of Agricultural and Natural Resources, Factsheet #13.
5-11
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6.0 Horses
6.1 Introduction
In 1900, the Census of Agriculture indicated that 79 percent of all farms had horses, whereas by 1992 this percentage
had dropped to 18 percent. Specifically, the 1992 Census of Agriculture reported 338,346 farms with 2,049,522
horses. Today's horse industry is quite diverse, providing animals for pleasure, showing, breeding, racing,
farm/ranch, and other uses. Because the horse industry is so diverse and much of the population is off farm, statistics
on horse population sizes, distributions, and trends are much less available than they are for other agricultural
livestock. The USD A estimates that up to 3 million of the approximately 5 million horses in the United States are
raised off farms or on farms with too few animals to be reported in the Census data (APHIS, 1996). However, a
study of equids (domestic horses, miniature horses, ponies, mules, donkeys, and burros) was recently completed for
28 states representing more than three-fourths of the U.S. horse and pony inventory on farms (APHIS, 1998a). In
addition, 133 race tracks participated in portions of this survey. Participation and accounting for race tracks is
important since some facilities are very large. The Lone Star Park at Grand Prairie located near Dallas/Fort Worth,
Texas, has accommodations for up to 1,250 horses. It is also believed that since mules, donkeys, and burros
represented only 4.7 percent of the animals, this survey is useful for characterizing the horse sector.
For the surveyed states, 40.1 percent of the equids are located in Texas, Oklahoma, Louisiana, Maryland, Virginia,
Kentucky, Tennessee, Alabama, Georgia, and Florida; 13.0 percent are located in Ohio, Pennsylvania, New Jersey,
and New York; 20.7 percent are located in Kansas, Missouri, Illinois, Indiana, Michigan, Wisconsin and Minnesota;
and 26.2 percent are located in Montana, Wyoming, Colorado, New Mexico, Washington, Oregon and California.
More than 95 (96.3) percent of the operations have from 1 to 19 equids on the operation, representing 73 percent of
all equids. Less than 4 (3.7) percent of operations have 20 or more equids, representing 27 percent of all equids.
Overall, boarding/training and breeding operations account for 3.7 and 5.2 percent of the operations, yet account for
more than 10 percent of the equids (see Figure 6-1). Race tracks account for 53.4 percent of the operations with 20
or more equids, followed by boarding/training facilities (26.7 percent), breeding (22.7 percent), and farm/ranch (2.1
percent) (APHIS, 1998a).
Other
Residence
Farm/Ranch
Breeding Farm
Race Track
Boarding/Training
Facility
0 20 40 60
D Operations I Equids
Figure 6-1. Percent of operations and equids by primary function of operation (Source: APHIS, 1998a).
Nationally, stalls are provided on two-thirds of operations (does not include race tracks). New England states
provide stalls on nearly all (94.5 percent) of their operations, while about one-half of operations in the western
6-1
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United States provide stalls. For those operations that do provide stalls, about 70 (71.3) percent had at least one stall
per equid. About one-third (34.5 percent) of those operations with stalls clean them at least once a day, while about
one-half (50.2 percent) clean stalls once a week or less often. Straw, hay, wood shavings, chips, or sawdust are the
most common type of bedding. Less than 40 (36.4) percent of operations indicate that they usually or sometimes
compost manure or waste bedding on site. For those operations with more than 20 equids, the most common method
of disposal was to apply the waste to fields where no animals graze (30.7 percent), followed by applying it to fields
where livestock graze (29.7 percent), allowing manure/waste bedding to accumulate or leaving it to nature (15.1
percent), selling it or giving it away (11.5 percent), and hauling it away other than a landfill (8.9 percent) (APHIS,
1998b).
6.2 Waste Management Technologies
An average 1,000-pound horse generates approximately 9 tons of manure a year (51 pounds per day). Table 6-1
presents the characteristics of horse manure. The volume of this solid excrement ranges from 0.75 to 1.0 cubic foot
per day. Urine production ranges from 2.25 to 8 gallons per day depending upon diet, activity, and environmental
conditions (Wheeler and Cirelli, 1995). Depending on practices, substantial amounts of bedding are added to the
wastes.
Table 6-1. Horse "as excreted" manure characteristics.
Concentration
Component
(lb/day/AU)
Weight
51
Total solids
15
Volatile solids
10
Total Kjcldahl nitrogen
0.30
Total phosphorus
0.071
Total potassium
0.25
Source: ASAE, 1998.
The characteristics of the horse waste will vary by the type of diet fed to the animal, which can range from low-
nutrient crops such as Bermuda grass to nitrogen-rich forages such as clover, in addition to supplemental feeding.
Since horses unlike ruminants, are limited in their ability to use forages of low nutritive value, feeding regimes
require a greater level of management, especially for horses raised primarily on pastures.
In general nitrogen is easily lost from horse manure. Decomposition rates depend on handling and storage methods.
Horse manure should be kept compact and moist to prevent excessive losses. Manure left in loose heaps loses
nitrogen rapidly to the atmosphere in the form of ammonia. Nutrients in urine are readily available for crop use.
Additionally, bedding used in horse stalls absorbs and holds this valuable component well (Barney et al., 1990).
6.2.1 Waste Collection and Handling
Horse manure is best handled as a solid. As stated earlier, many operations collect manure from stalls and paddocks
regularly. This is usually done with a fork or shovel and a wheelbarrow, tractor-loader, or trailer. Daily maintenance
of horses in a confined setting requires intense labor requirements to maintain sanitary conditions for the housed
animals. Once manure and dirty bedding have been removed, wet areas might be treated with lime to maintain safe,
clean, and odor-free conditions (Wheeler and Cirelli, 1995). Fresh bedding, typically composed of such materials as
pine sawdust, peanut shells, peatmoss, rice hulls, and other absorbent materials, is added following removal of
manure and soiled bedding to ensure clean, dry conditions. Simply adding fresh bedding and allowing manure and
soiled bedding to accumulate in the horse stall results in dirty animals, provides excellent fly-breeding conditions,
and may be unhealthy to horses (Graves, 1987). Depending on conditions, the runoff from paddocks, pens, corrals,
and outdoor areas might need to be diverted to a settling basin or filter strip.
6-2
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Manure management in pastures depends primarily on good distribution of manure across the pasture. Rotational
grazing is a good option to avoid manure concentration in isolated spots in a pasture. Additionally, avoiding grazing
during rainy periods when soils are saturated is important to avoid soil compaction and manure runoff. Restricted
access to streams avoids manure deposition in or near water bodies. Also, damaging the grass stand increases the
potential for manure runoff from pastures. The risk of this can be reduced by refraining from excessive stocking
rates that lead to overgrazing (Colorado State University, 1996).
6.2.2 Waste Storage
Manure is typically stockpiled prior to use, providing greater flexibility for land application. The B.C. Government
(1998) recommends not to stockpile manure directly on the ground for long-term storage where there is high rainfall
or water tables. The size of any storage facility would depend on the number of animals housed. A facility 12 feet
wide by 12 feet long by 6 feet high can hold a year's worth of manure for a 1,000-pound animal (USDA, Spring
1997).
For horse operations that employ confined operations, an on-site storage facility is considered the most efficient way
to collect and contain manure. Manure storage facilities should receive as much attention and planning as any other
aspect of a horse operation (B.C. Government, 1998). Storage facilities are permanent structures designed and
operated to contain all manure until it can be applied as a fertilizer or removed for use elsewhere. Basic siting and
sizing considerations of storage facilities from the B.C. Government (1998) include the following:
c Located at least 15 meters (50 feet) away from any watercourse and at least 30 meters (100 feet) away from
wells or domestic water sources.
c Located so that clean surface runoff from adjacent areas is excluded.
c Sized to provide enough storage to prevent having to spread manure during the fall and winter or at any time
runoff is likely to occur.
c Of watertight construction.
c Structurally sound (with possible consideration of professionally engineered designs for both earthen and
concrete structures).
c Sized and located to contain all of the runoff expected from local climatic conditions, using figures from the
worst precipitation in 25 years.
c Adequately fenced to prevent the accidental entry of humans, animals, or machinery.
c Located out of sight and downwind from public places and neighboring residences (where possible).
c Covered in areas of the province receiving more than 600 millimeters (24 inches) of rainfall between October
and April.
6.2.3 Waste Treatment and Disposal
For smaller operations, composting is commonly used to treat horse manure. Composting produces a relatively dry
end-product that is easily handled and reduces the volume of the manure (40 percent to 65 percent less volume and
weight than the raw material). Ideal conditions for composting include a carbon-to-nitrogen (C:N) ratio between
25:1 and 30:1, a moisture content between 40 and 60 percent, and good aeration. Horse manure as excreted has a
C:N ratio of 19:1. With the addition of bedding, the C:N ratio usually increases to a level ideal for composting.
Under normal composting conditions, the internal temperature will increase to between 135 eF and 160 eF, killing
most pathogens, parasites, and weed seed. Properly constructed and maintained compost piles or windrows will
6-3
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finish composting in as few as 90 days, though the average time is approximately 120 days. When the composting
process is complete, the temperature cools naturally.
Compost can be reused on horse pastures. However, experience has shown in the absence of careful management,
this practce can spread internal parasites. Composted manure/bedding can also be used as a surface for riding areas
when mixed with sand and wood products. Shavings-based stall waste can often be used by nurseries and do not
require a complete composting process. Table 6-2 shows the average rates of horse manure application for forages
and should follow normal practices for minimizing runoff and leaching that are applicable for all manures.
Table 6-2. Average manure application rates and area requirements for forages.
Yield Annual
Yield
Horse Manure
Land Base Needed
Forage
(tons/acre)
(tons/acre)
(acres/horse/yr)
Alfalfa
4
30
0.3
Alfalfa-Grass
4
20
0.4
Bentgrass
2
21
0.4
Big Bluestem
3
10
0.9
Birdsfoot Trefoil
3
25
0.4
Bluegrass
2
19
0.5
Bromegrass
3
19
0.5
Little Bluestem
3
11
0.8
Orchard Grass
4
20
0.5
Red Clover
3
20
0.4
Reed Canary Grass
4
18
0.8
RyeGrass
4
22
0.3
Switchgrass
3
12
0.8
Source: Colorado State University, 1996.
6.3 Bibliography
APHIS. 1996. The USDA's Role in Equine Health Monitoring, . U.S.
Department of Agriculture, Animal and Plant Health Inspection Service.
APHIS. 1998a. National Animal Health Monitoring System, Parti: Baseline Reference of1998 Equine Health and
Management, . File eq98ptl.pdf accessed October 15, 1998.
U.S. Department of Agriculture, Animal and Plant Health Inspection Service.
APHIS. 1998b. National Animal Health Monitoring System, Part II: Baseline Reference of1998 Equine Health and
Management, . File eq98pt2.pdf accessed October 15, 1998.
U.S. Department of Agriculture, Animal and Plant Health Inspection Service.
ASAE. 1998. ASAE Standards 1998. ed. American Society of Agricultural Engineers, St. Joseph, MI.
Barney, S., P. Davis, N.R. Deuel, F.E. Gilman, J. Hodson, B.A. Marriott, J.D. Minnick, T.F. Mitchell, J.R. Mitchell,
E. Poole, E.S. Taylor, 1990. Good Neighbor Guide for Horse-Keeping: Manure Management. New
Hampshire Department of Environmental Services, University of New Hampshire Cooperative Extension,
New Hampshire Department of Agriculture, U.S. Department of Agriculture, Soil Conservation Service.
B.C. Government. 1998. Manure Management Chapter 8, Horse Owner. Ministry of Agriculture and Food,
Planning for AgridMtis4i Columbia Government.
6-4
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Cirelli, A. Jr., and B. Cloud. 1994. Surburban Horse Keeping. Fact Sheet 94-09. University of Nevada Cooperative
Extension.
Colorado State University. 1996. Management of Horse Manure: A Renewable Resource. Colorado State
University Cooperative Extension, Fort Collins, CO. December 1996.
Graves, R.E. 1987. Animal Manure-Manure Management for Horses. PENpages Number: 0870177.
Pennsylvania State University Agricultural Engineering Department
King, Marcia. 1997. Manure Management. Horse Interactive, October 1997.
Ohio State University. 1992. Ohio Livestock Manure And Wastewater Management Guide. Bulletin 604.
Santa Monica Bay. 1996. Horses and Livestock. Santa Monica Bay Restoration Project.
.
USD A. 1997. Horses: A Common Sense Approach. U.S. Department of Agriculture. Spring. 1997.
USEPA. 1994. Pollution Control for Horse Stables and Backyard Livestock. Rural Nonpoint Source Management.
U.S. Environmental Protection Agency, Region 6, Water Management Division, Water Quality
Management Branch, Dallas, TX. Publications Division, Washington, DC.
Wheeler, Gene, and A. Cirelli. 1995. Animal Waste Management for the Horseowner. Fact Sheet 95-11, University
of Nevada Cooperative Extension, Lincoln, Nebraska.
6-5
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7.0 Ducks
7.1 Introduction
The most popular market duck raised for meat production in the United States is the Pekin duck. These ducks are
relatively easy to raise because they are hardy and not susceptible to common poultry diseases. Small farms use
barns or simple shelters to house the birds and often provide access to pastures or ponds for grazing and exercise.
Large-scale operations, however, confine ducks year-round and seldom incorporate outside ranges or swimming
(Hearn and Gouderham, 1988; Scott and Dean, 1991).
Modern confinement housing is similar to that used in the poultry industry for broilers and roasters, as described in
Chapter 10. Barns are constructed with clear-span trusses and equipped with mechanical ventilation and heating
systems. Common floor designs for duck houses include all wire mesh, solid floors with litter, or a combination of
the two. Wire mesh floors are constructed over concrete pits that collect the duck manure. Solid floor systems are
bedded with 4 to 6 inches of straw or wood shavings to help dry the waste and keep the animals comfortable. To
keep the litter as dry as possible, solid floor systems should place drinkers over wire mesh. This helps to collect
spilled water and waste and reduces the frequency of manure clean-out. Pelleted feeds and automatic hopper-type
feeders are the standard for intensive duck operations. A constant supply of fresh water is essential because ducks
consume about five times as much water by weight as food. Most conventional poultry drinking systems such as
bell, trough, and nipple drinkers are suitable for ducks.
The housing floor design and age of the ducks dictate the amount of area required to raise each bird (Table 7-1).
Age groups are kept isolated, either in separate buildings or in the same buildings with solid partitions between them.
It is common for the female ducks and male drakes to be reared together. Breeding ducks are kept in breeder houses
similar to turkey pole-barns. The mature ducks are typically bred at a ratio of one drake to five or six ducks. Nest-
boxes are commonly filled with bedding and provided at the rate of one space for every five or six ducks. Eggs are
fertile about 3 days after the first mating and should be routinely collected from the nests, washed, and placed in
incubators. When the ducklings hatch, they are moved to a separate brooder house or isolated from the rest of the
flock behind a partition. Ducklings are brooded at a minimum temperature of 80 eF for the first week. The
temperature in the brooder house is gradually reduced over the next 2 weeks until heating is no longer required. At 3
weeks of age the ducklings are moved to their rearing quarters, where they remain until selected for market (7 to 9
weeks of age) or added to the breeding stock. The benefits of modern confinement duck production are the ability to
market the birds at an earlier age, improve feed conversion, obtain more predictable weight gain, and better control
disease.
Table 7-1. Recommended indoor floor area per duck.
Age (weeks)
All Wire Floor (ft2)
Wire and Litter3 (ft2)
All Litter" (ft2)
1
0.25
0.25
0.3
2
0.4
0.5
0.6
3
0.6
0.9
1.1
4
0.9
1.2
1.5
5
1.1
1.5
1.9
6
1.3
1.8
2.25
7
1.5
2.0
2.5
Developing Breeders
Not Recommended
2.5
2.7
Laving Breeders
Not Recommended
3.0
3.0
" Wire covering 1/4 to 1/3 of the total floor area. b All litter except for narrow screen underwaterers.
Source: Scott and Dean, 1991.
7-1
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7.2
Type and Size
7.2.1 National Distribution
The 1992 Census of Agriculture reported an inventory of nearly 3.5 million ducks in the United States (Table 7-2).
This represented more than a 26 percent drop from 1987. The number of farms dropped from about 25,000
operations in 1987 to about 16,000 operations in 1992. The specialized husbandry for ducks has limited expansion
due to the fact that duck production "know-how" has tended to remain within families or in large companies (Scott
and Dean, 1991). Duck farms must also be located in close proximity to processing plants specially adapted to
handle ducks. These factors, as well as the specialized market for duck meat in the United States, have played an
important role in limiting the expansion of the duck industry.
Table 7-2. Duck inventory and sales.
Category
1987
1992
Total ducks Inventory
Number of farms
4,538,716
24,664
3,339,659
16,312
Duck sales Sold
Number of farms
26,041,817
4,262
16,391,031
3,038
Source: 1992 Census of Agriculture.
7.2.2 Regional Distribution
Ducks were first produced commercially in the United States on Long Island, New York. The major producers are
now located in the Midwest and California. Indiana produces the majority of commercial ducks, followed by
Wisconsin, California, New York, and Pennsylvania (Table 7-3).
Table 7-3. 1992 regional distribution of commercial ducks.
State
Inventory
Farms
Indiana
1,170,154
388
Wisconsin
695,109
653
California
526,610
806
New York
312,523
524
Pennsylvania
152,855
653
Source: 1992 Census of Agriculture.
7.3 Waste Management Technologies
7.3.1 Nutritional Strategies
Nutritional strategies followed by duck farmers are primarily designed for rapid growth and optimum egg
production. The nutritional programs are not directly intended to reduce the quantity or nutrient content of the
manure. One study, however, reported a 10 percent improvement in nitrogen utilization in ducks when their feeds
were treated with both pectinase and hemicellulase enzymes (Scott and Dean, 1991).
7.3.2 Waste Collection
The two varieties of housing and floor design influence the waste collection process. The manure-litter mixture that
accumulates in solid floor houses is completely cleaned out between flocks with power equipment, such as skid
steers and front-end loaders. Houses with wire mesh floors collect manure in concrete pits. This waste is either
collected with mechanical scrapers or pressure-washed and drained from the pit into storage tanks or lagoons.
7-2
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7.3.3 Waste Storage, Handling, and Treatment
The proper use of duck manure can add to the fertility and productivity of cropland. If not managed properly, duck
waste can cause odor and fly problems and pollute ground and surface waters. The best handling and treatment
methods for preventing these problems depend on the type of housing and the characteristics of the manure collected.
Fresh duck manure has a slightly different composition than other types of animal manure (Table 7-4). The manure
can be handled and managed as either a dry litter (similar to broiler production) or a semisolid or liquid (similar to
some layer production systems).
Table 7-4. Composition of fresh manure for a variety of animals.
Kind of Manure
% Water
% N
%P
% K
Duck
61
1.1
1.45
0.5
Goose
67
1.1
0.55
0.5
Hen
73
1.1
0.9
0.5
Turkey
74
1.3
0.7
0.5
Hog
87
0.55
0.3
0.45
Horse
80
0.65
0.25
0.5
Source: Florida Agricultural Information Retrieval System, 1998.
The amount of manure produced depends on the number of birds, the amount and type of feed, and the age of the
birds. Table 7-5 presents estimates for manure production by poultry. Manure storage facilities should be sized to
allow the waste to be spread when crop and field conditions are appropriate. There are many different types of dry
litter storage facilities, including covered stockpiles, bunkers, and roofed structures.
Table 7-5. Approximate manure production by poultry.
Type of Bird
Market Wt.
(lb)
Feed Eaten/Animal (lb/yr)
Manure Produced
(lb/yr/animal)
Layer
4
77
15.4
Pullet
3
30
6.0
Broiler
4
54
10.8
Roaster
7
72
14.4
Turkey
20
120
24.0
Duck
7
114
22.8
Source: Jordan and Graves, 1996.
Covered stockpiles are the simplest and cheapest storage structures to design and construct. Manure is stacked on
compacted material or a concrete pad located on high, well-drained ground. Plastic sheeting weighted with old tires
is commonly used to cover the pile. Diversion ditches constructed around the pad further limit any contact with
runoff. Bunker-style storage structures are built above the ground or into the ground and require similar pollution
prevention measures. The bunkers are built with 6- to 10-foot-high parallel walls and a concrete floor that allows for
easy loading and unloading. The most costly but effective dry litter storage facilities have a permanent roof.
Construction estimates for these structures are between $3 and $5 per square foot for materials plus additional labor
costs. Walls are typically constructed of pressure-treated wood or concrete. Roofs should be clear span with trusses
10 to 18 feet above the floor and support posts along the outside walls. This design allows the litter to be stacked
high and permits easy access with power equipment. Manure collected as a semisolid or liquid is typically stored in
tanks or lagoons outside the house.
Dry litter, duck manure, and carcasses can be treated by composting the materials. Composting aerobically reduces
the organic content through microbial decomposition. The process requires a material with minimal compaction,
proper temperatures (135 to 160 eF), 40 to 60 percent moisture content, and the appropriate carbon-to-nitrogen ratio
7-3
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(25:1 to 30:1). The end-product looses more than one-half the initial volume due to losses of carbon dioxide and
water to the atmosphere. Most nutrients are retained in the material along with organic matter that did not
decompose during composting. This makes finished compost a valuable soil amendment that can be sold or added to
the farmer's land.
Large-scale duck operations also use a variety of treatment technologies to manage semisolid or liquid wastes.
These technologies have been implemented in other concentrated animal operations, including the chicken and
turkey industries. Liquid waste treatment processes include anaerobic digestion in lagoons or tanks, aerobic
digestion with mechanical aerators, constructed wetland systems, and scaled-down multistage treatment plants.
7.3.4 Waste Disposal and Use
Waste disposal techniques and environmental concerns are similar for the duck and poultry industries. Although
older duck operations and small operations might still provide access to water, large-scale operations confine ducks
year-round and seldom incorporate outside ranges or swimming (Hearn and Gouderham, 1988; and Scott and Dean,
1991). Thus, solid waste is typically disposed of by spreading it on hay land, pasture, or cropland with a wagon, box
spreader, or flail spreader. The equipment should be calibrated to ensure proper application rates and to minimize
pollution potential. The correct application rate takes into account the nutrient content of the soil and manure, as
well as the type of vegetation that will use the nutrients. If the manure is not immediately worked into the soil by
tillage, runoff potential increases and most of the volatile nitrogen compounds will be lost to the atmosphere as
ammonia.
Liquid waste is also disposed of by applying it to land. Liquids can be pumped onto the land and irrigated, broadcast
with tank wagons, or incorporated into the soil with subsurface injection equipment. Manure should not be applied
to land near wells or springs or on slopes adjacent to surface waters. Vegetated buffer strips maintained along these
waters and drainage ditches can provide additional surface water quality protection.
7.3.5 Examples of Typical Systems
Generally, ducks raised on small farms are housed in barns or poultry sheds with packed earthen or concrete floors.
Bedding, such as straw or wood shavings, is used to dry the manure and keep the animals comfortable. The manure
is removed manually or with power equipment at different intervals depending on the number of ducks and the
season. The manure is then stored temporarily on a concrete pad or in a shed and then land applied. Some
operations compost the manure and either sell the compost to sod farms or neighboring crop farms or apply the
compost to their own land.
The large operations sometimes handle duck manure as a solid. Older barns or structures with solid floors
accumulate a manure-litter mix that is removed between flocks with skid steers or front-end loaders. The solid
manure is transported to a storage structure or directly applied to land. This system is comparable to the system used
with the production of broilers.
Newer duck housing facilities use wire floors over deep pits and handle the waste as a semisolid or liquid. These
facilities do not use bedding, so the manure drops through the wire floor and collects into concrete pits. The manure
is mechanically scraped or pressure washed from the pit and pumped to a holding tank or lagoon outside the house.
This waste can be directly applied to land, stored, or sent to an on-site waste treatment system. Common systems
include anaerobic digestion in lagoons or tanks, aerobic digestion with mechanical aerators, constructed wetland
systems, and scaled-down multistage treatment plants.
Examples from Telephone Interviews
A commercial duck farm on Long Island, New York, produces 800,000 to 900,000 birds per year
(approximately the sixth largest producer in the United States). The ducks are housed on wire floors over a
concrete base. The manure is scraped and pressure washed into a holding tank and then enters a treatment
system. The waste is first processed in a primary clarifier and the effluent enters an activated sludge lagoon.
7-4
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Solids from the clarifier are land injected or composted. Effluent that enters the lagoon is aerated mechanically
(15-day retention) and eventually is pumped to 6 acres of artificial wetlands for finishing. The wastewater
processed by the wetlands is reused as wash-down water or is emptied onto sand beds for groundwater
infiltration.
Maple Leaf Farms is the largest duck operation in the United States and raises nearly 70 percent of all the ducks
produced. The company maintains three farms in Indiana, Wisconsin, and California along with smaller
contract farms. Duck manure is managed as both a solid and a liquid depending on the age and design of the
house. Solid-floor houses use bedding (pine shavings or curls), and the manure-litter mixture (40 to 60 percent
moisture) is removed from the house. The manure-litter mixture is then stored on a concrete pad and
composted. The compost is sold to sod farmers or neighboring farms or land applied off site. The bedded
houses are more labor-intensive and are best suited for smaller operations (older facilities and family-run farms).
Bedding costs are approximately $50 to $70 per ton.
The Maple Leaf Farm facilities also manage duck waste in liquid form. In the newer houses, liquid waste is
collected in deep pits under wire mesh floors. The liquid waste is scraped and washed from the pits to a 2000 to
5000-gallon holding tank outside the house. This waste either is land applied or enters a treatment system. The
system (60,000 to 80,000 gallons treated per day) decants liquid off the top of the holding tank. The liquid
waste goes to a rotor screen to remove solids and then enters a high-rate anaerobic digester. The digestor waste
then goes to a digester clarifier, and the clarifier effluent enters an aerobic activated sludge plant. After being
clarified, the final effluent is spray irrigated on canary grass, alfalfa, or corn. The process reduces BOD from
15,000 to less than 50 and total N from 251b/1000gal to 100 to 200 ppm). All solids wasted from the process
are land applied. The treatment facility costs are approximately $500,000 per year to treat 200 million gallons
of waste. This cost covers transport, treatment, capital costs, etc.
7.3.6 Component/Unit Cost
Waste management system costs are not provided in the literature. The costs, however, would include the capital
costs of housing and storage facilities, bedding material (straw or wood shavings), and handling equipment. Liquid
waste systems would include additional costs for irrigation and/or injection equipment, pumping, and constructing
and operating specialized treatment systems. Income-generating arrangements, such as selling compost to nearby
farmers, could potentially reduce or offset some of these costs. Estimates from farmers, however, indicate that waste
treatment costs can be very high, especially if land area for application is not abundant.
7.4 Bibliography
Clauer, Phillip J. 1998. Management Requirements for Waterfowl.
. Accessed July 16, 1998.
Corwin, Douglas. 1998. Personal communication.
Eghbal, Bahman. 1998. Composting Manure and Other Organic Residues.
. Accessed July 14, 1998.
Florida Agricultural Information Retrieval System. 1998. Animal Manures.
. Accessed July 15, 1998.
Fulhage, Charles D. 1993. Storing Poultry Litter, .
Accessed July 15, 1998.
Geiger, Glenn and Harold Biellier. 1993. Brooding and Rearing Ducklings and Goslings.
. Accessed July 15, 1998.
7-5
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Graves, Robert E. 1994. Dairy Manure Handling. Agricultural and Biological Engineering Extension Fact Sheet.
University Park, PA.
Hamre, MelvinL. 1994. Raising Ducks. . Accessed
July 15, 1998.
Hearn, P.J. andK.R. Gooderham. 1988. Management and Welfare of Farm Animals. London, 243-253.
Jordan, H.C. andR.E. Graves. 1996. DER Poultry Management, .
Accessed July 15, 1998.
Maple Leaf Farms. 1998. Personal communication.
Minnesota Department of Agriculture. 1995. Manure Management Alternatives: A Supplemental Manual.
Agriculture Planning and Development Division.
Minnesota Department of Agriculture. 1998. Feedlot and Manure Management Fact Sheets.
. Accessed July 14, 1998.
Nova Scotia Agriculture and Marketing. 1997. Housing, Feeding, and Management of Duck Breeders.
. Accessed July 15, 1998.
Nowland, W.J. 1996. Raising Ducks. . Accessed July 15,
1998.
Ohio State University Extension. 1998. Best Management Practices: Land Application of Animal Manure.
. Accessed July 15, 1998.
Oklahoma State University Extension. 1997. Duck Breeds, . Accessed
July 15, 1998.
Purdue Cooperative Extension Service. 1998. Poultry Manure Management Planning.
. Accessed July 15, 1998.
Schmitt, Michael and George Rehm. 1998. Fertilizing Cropland with Poultry Manure.
. Accessed July 15, 1998.
Scott, M.L. and W.F. Dean. 1991. Nutrition and Management of Ducks. M.L. Scott of Ithaca, Ithaca, NY.
U.S. Department of Commerce. 1992. 1992 Census of Agriculture: United States Summary and State Data.
. Accessed July 17, 1998.
7-6
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8.0 Goats
8.1 Introduction
Goats are raised for a variety of purposes and provide consumers with milk, cheese, fiber, meat, and leather. In the
United States, Angoras are by far the most popular goat commercially produced, followed by dairy goats. Goats
raised for meat, such as the Spanish meat goat, the Boer goat, and sometimes the Angora, represent a relatively new
and developing market.
Goats are ruminants and will readily forage on grasses, shrubs, and woody plants not preferred by sheep or cattle.
Because of this feeding behavior, they can often be raised on marginal lands that are not fertile enough for other
livestock. A large number of Angora and meat goats in the southwestern United States are maintained under range
conditions, where they are grazed year-round in herds or loose grazed (unherded) in fenced areas. Both meat and
Angora goats are extensively managed with minimal supplemental feed, limited or simple shelter, and minimal health
care practices. Dairy goats, on the other hand, are intensively managed with special housing systems, supplemental
feeds, and limited or no grazing area.
Goat husbandry techniques vary depending on the type of goat and the size of the farm. For large-scale meat and
Angora operations, the male goats, called bucks, can be raised separately or herded year-round with the females,
known as does. During the seasonal mating season from August to March, 3 to 4 bucks can be used to mate around
100 does in a herd. Pregnant does are given feed supplements and are eventually separated into clean straw-bedded
pens to deliver the young, called kids. After a gestation period of about 21 weeks, domestic does usually give birth
to one to three kids at a time. In commercial fiber and meat operations, kids are either separated into pens or corrals
or remain with their mothers as a suckler herd until weaned at around 12 to 14 weeks. Replacement does that are not
marketed for meat are returned to the breeding herd at about 1 year of age. Spanish and Boer meat goats are ready
for market at 4 or 5 months of age, while Angoras are clipped for mohair every 6 months and then marketed for
meat after 2 to 3 years (4 to 6 clippings).
Dairy operations typically keep bucks and does in separate pens until they are bred. One buck can mate with 30 or
40 does in a mating season. Some dairies use artificial insemination to better control the breeding period and limit
the seasonal disruption to milk production. Pregnant does are given feed supplements and placed in maternity pens
to deliver their kids. After a day or two, the kids are moved to kid pens.
The two main methods of housing dairy goats are loose housing and tie stalls or individual confinement. In loose
housing, the goats rest together in a common area except at milking time (Figure 8-1). The goats have the freedom
to exercise, and the building construction and maintenance costs are minimized. Stall housing confines the goats into
rows of individual stalls and requires less space per animal (Figure 8-2). The advantage of confinement stalls is that
the goats can be individually fed and cared for; the disadvantage is that the system increases housing and labor costs.
8.2 Type and Size
8.2.1 National Distribution
The 1992 Census of Agriculture reported an inventory of over 2.5 million goats (Table 8-1). Nearly 2 million of
these were Angora goats. The U.S. milk goat inventory dropped from about 130,000 animals in 1987 to roughly
125,000 in 1992. The census reports that the number of dairy farms declined at an even greater percentage rate over
the same period. The U.S. meat goat inventory is not specifically reported in the census, but it represents some
portion of the "other goats" category in Table 8-1. This category of goat production grew by nearly 50 percent from
1987 to 1992.
8-1
-------
BEDDED AREA \
—JW.TOEPWttt:
MATERNITY & KID PENS I
PAVED EXERCISE AREA
WATER BOWL
Figure 8-1. Loose housing for dairy goats (Source: Ensminger and Parker, 1986).
MILKING
Figure 8-2. Individual stall housing for dairy goats (Source: Ensminger and Parker, 1986).
-------
Table 8-1. Goat inventory and sales.
Goat Varietv
1987
1992
Total goats
Inventory
Number of farms
2,246,587
45,032
2,515,541
47,164
Angora goats
Inventory
Number of farms
1,702,166
5,352
1,799,280
6,150
Milk goats
Inventory
Number of farms
129,225
15,443
124,718
11,559
Other goats
Inventory
Number of farms
415,196
29,354
591,543
34,901
Source: 1992 Census of Agriculture.
8.2.2 Regional Distribution
Angora goats are primarily raised in the southwestern United States. Texas produces the greatest number of Angoras
by far, followed by Arizona, New Mexico, and Oklahoma (Table 8-2). Between 1987 and 1992, Texas and
Oklahoma increased production, while Angora inventories in Arizona and New Mexico decreased.
Table 8-2. Regional distribution of angora goats.
State Producer
1987
1992
Percent Change
Texas
1,419,310
1,498,037
5.5
Arizona
109,529
73,164
(33.2)
New Mexico
81,064
62,648
(22.7)
Oklahoma
37,501
46,796
24.7
Source: 1992 Census of Agriculture.
Dairy goats are produced throughout the United States, with no region dominating the market. California is the
number one producing state, closely followed by Texas, Wisconsin, and New York (Table 8-3).
Table 8-3. Regional distribution of dairy goats.
State Producer
1987
1992
Percent Change
California
16,055
16,593
3.3
Texas
10,559
11,727
11.1
Wisconsin
5,562
7,677
38.0
New York
5,234
5,746
9.8
Source: 1992 Census of Agriculture.
8.3 Waste Management Technologies
8.3.1 Nutritional Strategies
Nutritional management for Angora and meat goats raised on rangeland is minimal. Dairy goat nutrition is managed
more intensively to maximize milk production. Neither nutritional management strategy, however, is used to reduce
the quantity or nutrient content of the manure.
8.3.2 Waste Collection
The quantity of manure produced varies according to the number of animals, type of feed, and amount of bedding.
Daily manure production (feces and urine) from goats of various weights is outlined in Table 8-4. Manure is
collected from exercise yards, bedded pens or packs, stalls, or from pits below slatted floors. In either case, the
8-3
-------
manure is normally handled as a solid because it does not liquify well and is unsuitable for liquid manure handling
and treatment systems. Goat manure produced daily equals about 5 percent of body weight and contains 60 to 70
percent moisture. Housing systems that use bedding of straw or wood shavings help to further dry the manure and
create a pack. The pack is collected regularly by hand or power equipment, depending on the number of animals.
Feeding and watering areas must be scraped more frequently (every 1 to 3 days) to remove clumps of litter and keep
the goats clean and dry. Manure must also be collected from the milking parlor although dairy goats tend to deposit
very little manure in this part of the facility. Milking parlor waste is either handled as a solid or washed as a semi-
solid into an outside storage tank or lagoon. Goats raised on pasture or rangeland distribute their manure when
grazing. This manure is normally not collected unless the land area is too small for the number of animals stocked.
Barns designed with slatted floors have more specialized manure collection systems. The manure falls through the
slats and into a concrete pit or gutter, where it is removed manually or by a mechanical scraper. A mechanical
scraper system has one or more scraping blades pulled by a chain or cable. Common scraper systems are gutter
cleaners, below-slat scrapers, and alley scrapers. These systems allow more frequent removal of manure and can
reduce daily labor requirements.
Table 8-4. Daily manure production by individual goats.
Goat Weight
Manure Weight (lb)
Manure Volume (in3)
7
0.3
8
27
1.1
31
47
1.9
53
67
2.7
76
87
3.5
98
107
4.3
121
147
5.9
166
187
7.5
211
Source: Ensminger and Parker, 1986.
8.3.3 Waste Storage, Handling, and Treatment
The characteristics of goat manure influence the types of storage, handling, and treatment systems selected. Goat
manure is handled by hand (shovel or fork) or power equipment, depending on the size of the operation. The waste
is easiest to manage as a solid, especially when collected with bedding material. Large quantities of manure require
storage facilities that can be accessed with power equipment, such as skid-steers and small front-end loaders. About
1 cubic foot per day of storage is needed for each 1,000 pounds of live goats. The total volume of storage should be
adequate to coordinate land spreading with field and crop conditions.
There are many different types of litter storage facilities, including covered stockpiles, bunkers, and roofed
structures. Covered stockpiles are the simplest and cheapest storage structures to design and construct. Manure is
stacked on compacted material or a concrete pad located on high, well-drained ground. Plastic sheeting should be
used to cover the pile and diversion ditches constructed around the pad in order to limit any contact with runoff.
Bunker-style storage structures are built above the ground or into the ground. They have parallel walls 6 to 10 feet
high and a concrete floor that allows for easy loading and unloading. Cover, such as plastic sheeting weighted with
old tires, is commonly used to prevent the manure from coming into contact with and polluting runoff.
The most costly but effective storage facilities have a permanent roof. Construction estimates for these structures are
between $3 and $5 per square foot for materials plus additional labor costs. Walls are typically constructed of
pressure-treated wood or concrete. Roofs should be clear-span with trusses 10 to 12 feet above the floor and support
posts along the outside walls. This design allows the litter to be stacked high and permits easy access with power
equipment. Goat manure is typically not treated before being disposed of on land. An exception is composting,
8-4
-------
which is an aerobic treatment process controlled by microbial action. The process requires a material with minimal
compaction, 40 to 60 percent moisture content, and the appropriate carbon-to-nitrogen ratio (25:1 to 30:1).
Composting generates heat (120 to 160 eF) and decomposes the manure into a stable and dry humus-like material.
The end-product is typically one-half the initial volume due to losses of carbon dioxide and water to the atmosphere.
Most nutrients are retained in the material. This makes finished compost a valuable fertilizer and soil amendment
that can be sold or land applied.
8.3.4 Waste Disposal and Use
The most common practice of manure disposal is applying the waste to hay fields, pasture, or cultivated land
(Graves, 1986). Manure removed from the barns, milking parlor, and exercise yards is either disposed of directly or
stored for future land application. To limit nutrient losses, odors, and pollution potential, manure must be applied
correctly. Proper timing and application rates can reduce nutrient losses through mineralization, volatilization,
denitrification, leaching, and erosion. Goat manure is best applied in the spring or throughout the growing season
when plants can use the nutrients and minimize environmental impacts on surface and ground water. The waste
should be applied to fields at agronomic rates suitable to the nutrient needs of the vegetation (Table 8-5).
Table 8-5. Nutrient removal rates for various crops.
Cron
Units
Nutrients Removed3
(lb/unit production)
N
P.O.
Corn, grain
bu
1.0
0.4
Corn, stover
ton
20.6
7.5
Corn, silage
ton
7.4
2.9
Soybeans, grainb
bu
—
1.0
Soybeans, residueb
ton
—
6.5
Wheat, grain
bu
1.3
0.5
Wheat, straw
ton
13.0
3.6
Oats, grain
bu
0.7
0.3
Oats, straw
ton
12.4
4.6
Barley, grain
bu
1.0
0.4
Barley, straw
ton
13.5
4.7
Rye, grain
bu
1.0
0.5
Rye, straw
ton
10.0
6.0
Alfalfa"
ton
—
11.0
Orchardgrass
ton
50.0
16.6
Bromegrass
ton
33.2
13.2
Tall fescue
ton
55.0
18.6
Blue grass
ton
25.8
18.3
Clover grassb
ton
41.0
13.3
Sorghum-Sudan grass
ton
39.9
15.5
^ix sources listing nutrient removal for a given yield were averaged to estimate removal for a unit of production.
bLegumes fix a proportion of their required nitrogen depending on soil status.
Source: Fulhage, 1993.
Goat manure is spread onto the land with wagons, box spreaders, or flail spreaders. The equipment should be
calibrated to ensure proper application rates and to minimize pollution potential. The correct application rate takes
into account the nutrient content of the soil and manure, as well as the type of vegetation that will use the nutrients.
If the manure is not immediately worked into the soil by tillage, runoff potential increases and most of the volatile
8-5
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nitrogen compounds will be lost to the atmosphere as ammonia (Table 8-6). Manure should not be applied to land
near wells or springs or on slopes adjacent to surface waters. Vegetated buffer strips maintained along these waters
and drainage ditches can also reduce water quality impacts.
Table 8-6. Manure nutrient loss by days until worked into soil.
Days Until Incorporation
% NH,-N Available to Plants
0-2
80
2-4
60
4-7
40
>7
20
Source: Fulhage, 1993.
Some goat farms dispose of the manure by hauling it off site to other farms, where it is composted or applied to land.
Transportation costs can be high, so this method is practical only if the farmer does not have enough land for proper
disposal.
Milking parlor wash water is sometimes handled as a semisolid and is disposed of in different ways. If the waste is
collected in storage tanks or lagoons, the solids are separated and land applied as mentioned above. The liquid waste
can be irrigated onto the fields or spread by tank wagon. One method to reduce potential air and water quality
problems is to incorporate the waste into the soil. This increases the amount of nutrients available to plants and
reduces volatilization of ammonia. Subsurface injection, however, is suitable only for liquid waste, and it requires
more time, labor, and costly equipment and maintenance than other disposal methods.
8.3.5 Examples of Typical Systems
Goat farms do not use a variety of intense waste management technologies common to other concentrated animal
operations such as swine or poultry production. The manure, with or without bedding, has been easy for farmers to
collect, handle, and manage as a solid. Typically, the waste management strategy is to dispose of the manure by
applying it to land with little or no treatment. To limit potential impacts or air and water quality, litter may be stored
until crop and soil conditions are appropriate for land application. Composting is a simple waste treatment processes
and is one of the few used by the commercial goat industry. The most common waste management systems for
different types of goats and farm sizes have already been presented. The following examples are provided as a
general overview.
Smaller-sized goat operations house the animals in barns or sheds and use bedding to dry the manure pack and keep
the animals comfortable. The litter is eventually removed from the barn manually or with power equipment and is
either directly land applied or temporarily stored and then disposed of. Some operations compost the manure and
apply it to their land or sell the compost as fertilizer to sod farms or neighboring crop farms. If land on the goat farm
is sufficient for application or a market for compost is not readily available, composting becomes a less cost-
effective management option.
Dairy goat operations of all sizes collect and handle the manure with the same solid waste management strategies.
An exception is that some of the manure deposited in the milking parlor may be handled as a semisolid and washed
from the building to a filter strip, storage tank, lagoon, or sanitary sewer. The volume of liquid waste is usually
small and can be irrigated onto the land when it begins to reach the capacity of the tank or lagoon. Solids collected
in the tank or lagoon can be separated and spread onto the land or composted.
Large commercial meat and Angora goat operations are generally operated on fenced pasture or rangeland. If the
land area is large enough, manure is dispersed on the range and naturally decomposes without the need for further
waste management. Because the goats are extensively managed, waste is seldom concentrated like it is with
intensive confinement operations. Potential water quality problems, however, can exist if the animals have access to
a stream or surface water. In these cases it is necessary to provide other watering sources and fence the animals out
of streambank areas.
8-6
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Examples from Telephone Interviews
Coach Farms is a 1200-head dairy goat farm located in New York. The animals are kept in barns with bedding,
and the litter is removed daily and spread on the fields. Milking parlor waste enters a settling tank before
entering a holding lagoon. The settling tank is periodically pumped out by a commercial septic tank company.
During the 15 years of operation, the lagoon has never been emptied and the waste applied to land.
Redwood Hills Dairy is located in California and raises about 300 goats. The animals are housed in barns with
straw bedding. The litter pack is removed twice each year (spring and fall) with a skid steer and is hauled off
site to either be used directly as fertilizer or composted. Renting the skid steer is the only cost incurred.
A dairy goat farm located in California raises about 500 goats. The manure is cleaned from the barn and stored
in a bin. It is then picked up for free by an independent company to be composted and later sold. The goats are
housed in open barns with pasture. Milking parlor wastewater is washed into a simple holding pond until it is
pumped onto the land.
8.3.6 Component/Unit Cost
Waste management system costs are not provided in the literature. The costs, however, would include the capital
costs of housing, bedding material (straw or wood shavings), and handling equipment. Income-generating
arrangements, such as selling compost to nearby farmers, could potentially reduce or offset collection and handling
costs. Dairy goat operations may have additional costs for lagoons or storage tanks used to store milking parlor wash
water.
8.4 Bibliography
Coach Farms. 1998. Personal communication.
Eghball, Bahman. 1998. Composting Manure and Other Organic Residues.
. Accessed July 14, 1998.
Ensminger, M.E., and R.O. Parker. 1986. Sheep and Goat Science. The Interstate Printers and Publishers, Danville,
Illinois, 246-303.
Fulhage, Charles. 1993. Land Application Considerations for Animal Wastes.
. Accessed July 14, 1998.
Graves, Robert E. 1994. Dairy Manure Handling. Agricultural and Biological Engineering Extension Fact Sheet.
University Park, PA.
Graves, Robert E. 1996. DER Managing Sheep and Goat Manure.
. Accessed July 14, 1998.
Graves, Robert E. 1986. Horse, Sheep, Goat, and Small Animal Manure Management. Document HS2,
Pennsylvania Department of Environmental Resources.
Haenlein, G.F.W. 1992. The U.S. Dairy Goat Industry. . Accessed July
14, 1998.
Jordan, R.M. 1990. Angora Goats in the Midwest. . 1990.
Minnesota Department of Agriculture. 1995. Manure Management Alternatives: A Supplemental Manual.
Agriculture Planning and Development Division.
8-7
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Minnesota Department of Agriculture. 1998. Feedlot and Manure Management Fact Sheets.
. Accessed July 14, 1998.
Ohio State University Extension. 1998. Best Management Practices: Land Application of Animal Manure.
. Accessed July 15, 1998.
Ohio State University Extension. 1998. Ohio Livestock Manure and Wastewater Management Guide. Bulletin 604.
. Accessed July 22, 1998.
Oklahoma State University Extension. 1996. Breeds of Livestock - Angora Goats.
. Accessed July 14, 1998.
Pinkerton, Frank, et al. 1991. Meat Goat Production and Marketing, .
Accessed July 14, 1998.
Pinkerton, Frank, et al. 1994. A Survey of Prevalent Production and Marketing Practices in Meat Goats of Southern
Origin. SRDC Publication No. 182.
Purdue Cooperative Extension Service. 1998. Poultry Manure Management Planning.
. Accessed July 14, 1998.
Redwood Hills Dairy. 1998. Personal communication.
Russel, A.J.F., and A. Mowlem. 1988. Management and Welfare of Farm Animals: Goats. London, 125-142.
Steevens, Barry, and Rex Ricketts. 1993. Feeding and Housing Dairy Goats.
. Accessed July 14, 1998.
USDA. 1993. The Goat Handbook. . U.S. Department of
Agriculture. Accessed July 14, 1998.
USDA-NRCS. 1997. Nutrient Management Code 590. U.S. Department of Agriculture, Natural Resources
Conservation Service. Alabama
U.S. Department of Commerce. 1992. 1992 Census of Agriculture: United States Summary and State Data.
. Accessed July 17, 1998.
Wilkinson, J.M., andB.A. Stark. 1987. Commercial Goat Production. BSP Professional Books, London.
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9.0 Swine3
9.1 Introduction
Swine production typically falls into three phases. Pigs are farrowed, or born, in farrowing operations. Baby pigs
are typically allowed to nurse for three to four weeks, then moved to a nursery, the second phase of swine
production. Young pigs are usually moved to a nursery at about 15 pounds. They remain at the nursery for seven to
eight weeks. They typically weigh about 60 pounds when they move from a nursery to a finishing operation. During
finishing, pigs are raised to market weight, 240 to 280 pounds. Finishing typically takes 15 to 18 weeks; hogs are
typically sent to market when they are 26 weeks old.
A farrow-to-finish operation includes all three production phases. A feeder pig operation is one that includes
farrowing and a nursery at one site. While some large farms continue to include the full range of production, from
farrow to finish, these are no longer the norm. More frequently in new operations, several specialized farms are
linked, or horizontally integrated, into a chain of production and marketing. Pigs begin in sowherds on one farm,
move to a nursery on another, and then move again to a grow-out farm for finishing. As each operation specializes,
it takes advantage of skilled labor, expertise, advanced technology, streamlined management, and modern housing.
But the primary advantage of specialization is disease control. In a farrow-to-finish operation, a disease outbreak
that begins in one phase of the operation can spread to other phases. Physically separating the phases makes it easier
to break this kind of disease cycle. At the same time, separating phases spreads the cost of establishing swine
operations, particularly if the different operations are owned by different persons.
Sows are usually bred for the first time when they are 180 to 200 days old. Artificial and natural insemination are
probably used equally to breed sows, although the use of artificial insemination appears to be increasing. A pig's
gestation period is 114 days. Sows usually average just over two litters per year, and an average litter is 10 or 11
pigs. A sow, therefore, usually gives birth to 23 or 24 pigs annually. Sows normally produce five to six litters
before they are culled and sold for slaughter at a weight of 400 to 460 pounds. Baby pigs are typically weaned 3 to 4
weeks after birth, and sows usually resume sexual activity within a week after a litter is weaned. Growers are able to
roughly synchronize production by weaning all their baby pigs on the same day. When they do this, all the sows in a
farrowing group become sexually active again at roughly the same time and may be bred again at the same time. The
sows then farrow at roughly the same time, over a period of about a week. In this way, growers are able to keep
groups of pigs together as they move from one phase of production to another. With the exception of some
Midwestern farmers, growers usually farrow relatively small groups of sows weekly.
While there are still many farms on which relatively small numbers of pigs are raised outdoors, the trend in the swine
industry is toward larger confinement farms where pigs are raised indoors. A typical confinement farrowing
operation houses 3,000 sows, although there are farrowing operations that house as many as 10,000 sows at one
location and farms that will house as many as 15,000 sows at one site are being planned.
The remainder of this section presents selected results from the Swine '95: Grower/Finisher Study that provides
more details about swine production practices. In this study, owners of operations with at least 300 market hogs
were interviewed twice. National estimates generated from this study were reported in Swine '95 Part II: Reference
of1995 Grower/Finisher Health and Management (May 1996). The states included in the two studies were
Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Michigan, Minnesota, Missouri, Nebraska, North Carolina,
Ohio, Pennsylvania, South Dakota, Tennessee, and Wisconsin. Information collected during these two studies and a
similar study done in 1990 provide an overview of environmental practices of U.S. pork producers.
Concerns about or regulations designed to protect environmental quality has led many producers to change or
develop management schemes during the 5 years prior to the Swine '95 study. Nearly 21 percent of the producers
3 This chapter is an abridged version of Chapters 1 through 4 of Draft Swine and Poultry Industry Characterization, Waste
Management Practices and Model Detailed Analysis of Predominantly Used Systems, prepared by North Carolina State University on September
30, 1998, under EPA Contract 68-C7-0014, Work Assignment 1-27.
9-1
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interviewed and more than one-half of the producers that market 10,000 or more hogs stated they had changed or
developed manure management programs (Table 9-1).
About one-third (36 percent) of producers who marketed 10,000 or more hogs from December 1, 1994, to May 31,
1995, also changed their dust control programs during the 5-year period. Many of these operations also changed
their programs for monitoring groundwater, surface water, and air quality (14.7, 18.8, and 9.8 percent, respectively).
These changes and those shown for employee training programs indicate a growing producer awareness of
responsible environmental management.
Table 9-1. Percent of swine operations that changed or developed waste management programs due to
environmental concerns or regulations affecting environmental quality.3
Type of Program
All Operations
Operations That Marketed More
Than 1,0000 Head
Manure management
20.9
52.6
Dust control in buildings
8.7
36.0
Surface water monitoring
5.7
18.8
Ground water monitoring
5.2
14.7
Employee training
4.6
43.2
Air aualitv monitoring
2.9
9.8
a Changes made during the 5 years prior to June 1995 interview.
Source: APHIS, 1995 and 1996.
Waste management systems used are shown for flooring type (Table 9-2) and waste storage (Table 9-3). The
predominant floor types include concrete, slats, and partial slats. The predominant waste storage systems included
anaerobic lagoon without cover, below-floor slurry or deep pit, and below-ground slurry storage. Below-floor slurry
or deep pits are more prevalent for operations that marketed between 2,000 and 9,999 hogs while anaerobic lagoons
without covers are more prevalent for operations that marketed more than 10,000 hogs.
Table 9-2. Waste management systems: types of flooring.3
Type of Flooring
Percent of Swine Operations
that use Flooring
Percent of Grower/Finisher
Pigs on this Flooring
Concrete slabs
26.3
38.8
Metal slats
3.6
0.8
Fiberglass or plastic slats
2.7
0.8
Slats and other flooring combined (partial slats)
33.0
23.9
Solid concrete
61.6
31.4
Dirt/pasture
12.1
3.2
Other
1.9
1.1
a Percentages based on number of pigs on hand on day of Swine '95 Interview.
Source: APHIS, 1995 and 1996.
Tables 9-4 through 9-7 summarize waste disposal methods used by swine operations. Nearly all operations dispose
of their waste on their farm (Table 9-4). Interestingly, only 4 percent of the nation's hog operations separate the
solid and liquid portions of waste. Tables 9-5 and 9-6 describes waste disposal by the operations that do not separate
their waste and that do separate their waste, respectively. Table 9-7 describes wastewater disposal by size of
operation.
9-2
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Table 9-3. Percent of swine operations using different waste storage systems.
Fewer Than
2,000-9,999
More Than
System
All Operations
2,000 Head3
Head3
10,000 Head3
Below-floor slurry or deep pit
49.9
43.6
70.4
47.9
Above-ground slurry storage
5.6
4.1
10.3
8.3
Below-ground slurry storage
19.4
17.3
25.6
26.3
Anaerobic lagoon with cover
1.8
2.2
0.5
2.0
Anaerobic lagoon without cover
20.9
17.4
29.2
81.8
Aerated lagoon
2.6
1.3
6.9
1.0
Oxidation ditch
2.2
2.9
0.1
0
Solids separated from liquids
4.6
4.1
5.9
4.7
Other
0.4
0.6
0
1.1
a Number marketed for slaughter during the 12-month period beginning December 1, 1994.
Source: APHIS, 1995 and 1996.
Table 9-4. Swine operation waste disposal methods.
Method
Percent of Operations Using Method
Applied to owned or rented land
97.3
Sold
0.8
Given away
4.2
Pay someone to remove
0.5
Other
1.0
Source: APHIS, 1995 and 1996.
Table 9-5. Waste disposal methods of swine operations that do not separate solids and liquids.
Method
Percent of Operations Using Method
Applied to owned or rented land
95.7
Sold
0.3
Given away
2.7
Pay someone to remove
0.3
Other
1.0
Source: APHIS, 1995 and 1996.
Table 9-6. Waste disposal methods of swine operations that separate solids and liquids.
Method
Solids
Liquids
Applied to owned or rented land
94.2
95.4
Sold
0.8
0.3
Given away
4.2
4.3
Pay someone to remove
0.5
0
Other
1.0
0
Source: APHIS, 1995 and 1996.
The most frequently reported waste management system used in 1990 was hand cleaning (41.6 percent), which
declined in use to 28.3 percent of operations in 1995, when pit-holding was used most (Table 9-8). Table 9-9
presents the prevalence of waste management system by production phase. Producers disposed of animal carcasses
most often by burying them, according to both the 1990 and 1995 studies (Table 9-10). Burning and use of
Tenderers decreased significantly as carcass disposal methods from 1990 to 1995. On-site composting increased as a
disposal method over the 5-year period.
9-3
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Table 9-7. Waste disposal methods used to dispose of liquid on owned or rented land (by percent)
All
Fewer Than
2,000-9,999
More Than
Method
Operations
2,000 Head3
Head3
10,000 Head3
Irrigation
12.8
8.8
24.1
55.3
Broadcast of solid spreader
57.9
63.3
41.9
10.5
Slurry (surface application)
46.0
42.6
58.3
33.2
Slurry (subsurface injection)
21.9
15.1
44.2
32.6
Other
0
0
0
0
a Number marketed for slaughter during the 12-month period beginning December 1, 1994.
Source: APHIS, 1995 and 1996.
Table 9-8. Most frequently used waste management systems.
Waste Management System
Percent of Producers Who Listed
the System as Most Used
Standard Error
None
5.1
+/- 1.9
Pit-holding
41.1
+/- 2.9
Mechanical scraper/tractor
10.1
+/- 1.8
Hand cleaning
28.3
+/-3.1
Flush-under slats
9.7
+/- 1.3
Flush-open gutter
3.2
+/- 0.9
Other
2.5
+/- 0.8
Source: APHIS, 1995 and 1996.
Table 9-9. Percent of operations using different waste management systems by production
phase.
System
Farrowing
Standard
Error
Nursery
Standard
Error
Grower/
Finisher
Standard
Error
None
13.8
+/-2.0
4.3
+/- 1.0
14.8
+/- 1.9
Pit-holding
25.5
+/-2.1
33.7
+/- 2.4
23.2
+/- 1.9
Mechanical scraper/tractor
12.0
+/- 1.6
17.6
+/- 2.2
24.9
+/- 2.0
Hand cleaning
38.2
+/- 2.6
29.9
+/- 2.9
27.2
+/- 2.4
Flush-under slats
5.3
+/- 0.8
9.4
+/- 1.3
2.4
+/- 0.5
Flush-open gutter
3.0
+/- 0.9
2.1
+/- 0.7
3.4
+/- 1.0
Other
2.2
+/- 0.5
3.0
+/- 0.8
4.1
+/- 0.8
Source: APHIS, 1995 and 1996.
Table 9-10. Percent of producers using different methods of carcass disposal,
Method
1990 National
Swine Survey
Standard Error
Swine '95 Total
Standard Error
Burial (on operation)
62.4
+/- 3.2
58.5
+/- 2.3
Burning (on operation)
21.6
+/-2.1
12.3
+/- 1.4
Renderer entering operation
26.6
+/-2.5
25.1
+/-1.8
Renderer at perimeter of
operation
29.0
+/- 3.3
6.9
+/- 0.9
Composting on operation
N/A
N/A
10.5
+/- 1.3
Other
17.6
+/- 2.2
7.2
+/- 1.3
Source: APHIS, 1995 and 1996.
9-4
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9.2 Demographics
9.2.1 National Change
The general trend in the U.S. swine industry is toward a smaller number of large operations (Table 9-11 and 9-12).
As the percentage of smaller producers decreases, there is a consistent increase in the percentage of herds with a total
inventory of 1,000 or more head. The number of U.S. swine operations has decreased more than 30 percent since
1990. A steady decline in the number of operations has occurred each year, with nearly a 50 (48.3) percent decrease
from 1990 to 1997 (Table 9-13). But the larger producers who are entering the industry raise more hogs, so the
overall number of hogs is increasing. The increase in the number of large operations has predominantly occurred in
conjunction with extended use of total confinement operations that separate the three production phases. On farms
with fewer than 500 hogs, the animals are still typically maintained outdoors.
Table 9-11. Percent of U.S. hog operations by herd size, 1990-1995.
Year
1-99 Head
100-499 Head
500-999 Head
1,000-1,999 Head
More Than 2,000
Head
1990
63.9
25.0
7.1
4.0a
a
1991
61.4
26.4
7.8
4.4a
a
1992
60.2
26.5
8.1
3.6
1.6
1993
61.1
25.3
8.3
3.5
1.8
1994
59.9
25.5
8.5
3.9
2.2
1995
59.4
25.0
8.7
4.3
2.6
a The 1,000-1,999 size group includes the more than 2,000 head.
Source: NASS, 1998.
Table 9-12. Percent of U.S. hog inventory by herd size, 1990-1997.
Year
1-99 Head
100-499 Head
500-999 Head
1,000-1,999 Head
More Than 2,000
Head
1990
6.4
28.6
23.8
41.2a
a
1991
5.5
27.2
23.4
43.9a
a
1992
5.3
25.3
22.0
18.9
28.5
1993
5.0
23.0
21.5
17.5
33.0
1994
4.5
20.5
20.0
18.0
37.0
1995
3.5
18.0
17.5
17.0
44.0
1996
3.0
15.0
15.0
16.0
51.0
1997
3.0
12.0
14.0
16.0
55.0
a The 1,000-1,999 size group includes the more than 2,000 head.
Source: NASS, 1998.
Table 9-13. Changes in the Number of U.S. swine operations (1990-1997).
Year
Number
Percent of Previous Year
Percent of 1990
1990
268,140
89.1
100.0
1991
247,090
92.1
92.1
1992
240,150
97.2
89.6
1993
225,210
93.8
84.0
1994
207,980
92.3
77.6
1995
181,750
87.4
67.8
1996
156,250
85.9
58.3
1997
138,690
00
00
00
51.7
Source: NASS, 1998.
9-5
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9.2.2 Regional Distribution
Swine farming historically has been centered in the Midwest in the United States; Iowa is far and away the largest
hog producer in the country (Table 9-14). Although the Midwest continues to be the nation's leading hog producer,
significant growth has taken place in other areas. Perhaps the most dramatic growth has occurred in North Carolina.
Over a decade, North Carolina has gone from being the 12 largest pork producer in the nation to second behind
Iowa. Climate has played a major role in the growth of North Carolina's swine industry. Figure 9-1 presents a
geographic distribution of the number of swine per county, and Figure 9-2 presents a geographic distribution of
operations with 1,000 or more swine in 1992, respectively.
Winters are mild and summers are tolerable, which has allowed growers to use open-sided buildings, which are less
expensive than the solid-sided buildings needed in the Midwest because of the cold winters. Midwestern growers
must also insulate or heat their buildings in the winter. North Carolina's pork boom was also fueled by tobacco
farmers who found hogs as a means of diversifying their operations. The idea of locating production phases at
different sites was developed in North Carolina.
Growth has occurred elsewhere as well. There has been significant growth in recent years in the panhandle area of
Texas and Oklahoma, as well as in northern Iowa and southern Minnesota. In the far West, hog farms have been
established in Utah and Colorado. In the Southeast, North Carolina remains by far the largest producer, but the
industry appears to be growing in Alabama and Mississippi.
Table 9-14. Number of swine operations in selected states by size group.3
State
1-99 Head
100-499 Head
500-499 Head
1,000-1,999
Head
2,000-4,999
Head
More Than
5,000 Head
1996
1997
1996
1997
1996
1997
1996
1997
1996
1997
1996
1997
Arkansas
2,100
1,900
230
240
60
60
100
90
70
70
40
40
Georgia
2,700
2,100
500
450
160
120
80
60
30
40
30
30
Illinois
2,900
2,600
3,300
2,600
1,300
1,200
830
660
370
340
100
100
Indiana
3,700
2,900
2,400
2,400
1,000
800
500
500
300
300
100
100
Iowa
4,600
4,500
8,900
6,800
4,300
3,500
2,300
2,000
700
980
200
220
Kansas
2,400
2,300
1,200
750
310
360
90
90
70
70
30
30
Kentucky
1,800
950
400
270
180
170
70
60
35
35
15
15
Michigan
3,200
2,800
750
820
170
180
150
150
100
120
30
30
Minnesota
5,000
4,900
3,300
3,100
1,400
1,400
800
850
350
400
150
150
Missouri
3,600
2,600
2,300
1,900
670
530
260
260
130
160
40
50
Nebraska
2,600
2,300
3,500
2,900
1,100
1,100
550
470
200
170
50
60
North Carolina
4,000
3,700
310
280
190
180
350
340
700
820
450
480
Ohio
7,000
6,500
2,200
1,700
490
490
200
200
90
90
20
20
Pennsylvania
3,800
3,400
800
600
220
200
180
160
80
115
20
25
South Dakota
1,200
950
1,600
1,200
450
400
150
150
60
60
40
40
Wisconsin
3,300
3,100
1,000
930
220
210
130
110
40
40
10
10
Other Statesb
37,700
34,800
3,500
3,000
780
730
450
420
115
130
105
110
United States
94,800
84,900
36,270
29,990
13,020
11,670
7,200
6.590
3.520
4,020
1.440
1.520
"An operation is any place having one or more hogs and pigs on hand any time during the year. b Individual state estimates are not available for the
34 states included in the Other States grouping.
Source: NASS, 1998.
9-6
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9.3
Waste Management Systems
9.3.1 Nutritional Strategies
Grinding. Fine grinding and pelleting are simple but effective ways to improve feed utilization and decrease
nitrogen and phosphorus excretion. By reducing the particle size, the surface area of the grain particles is increased,
allowing for greater interaction with digestive enzymes. When particle size is reduced from 1,000 microns to 400
microns, nitrogen digestibility increases by approximately 5 to 6 percent. As particle size is reduced from 1,000
microns to 700 microns, excretion of nitrogen is reduced by 24 percent. The industry average particle size is
approximately 1,100 microns, with the recommended size being between 650 and 750 microns. Reducing particle
size below 650 to 750 microns greatly increases the energy costs of grinding and reduces the throughput of the mill,
as well as increasing the incidence of stomach ulcers.
Amino acid supplemental diets. Supplementing the diet with synthetic lysine to meet a portion of the dietary lysine
requirement is an effective means of reducing nitrogen excretion by pigs. This process reduces nitrogen excretion
because lower-protein diets can be fed when lysine is supplemented. Research studies have shown that protein levels
can be reduced by 2 percentage points when the diet is supplemented with 0.15 percent lysine (3 pounds lysine-
HCl/ton of feed) without negatively affecting performance of grow-finish pigs. Greater reductions in protein are
possible, but only if threonine, tryptophan, and methionine are also supplemented.
Table 9-15 shows a theoretical model of the effect of feeding low-protein, amino acid-supplemented diets on
nitrogen excretion of finishing pigs. Note that reducing the protein level from 14 percent to 12 percent and adding
0.15 percent lysine results in an estimated 22 percent reduction in nitrogen excretion. Reducing the protein further to
10 percent and adding 0.30 percent lysine, along with adequate threonine, tryptophan, and methionine, reduces the
estimated nitrogen excretion by 41 percent.
Table 9-15. Theoretical model of the effects of reducing dietary protein and
supplementing with amino acids on nitrogen excretion by 200-lb finishing pig.ab
Diet Concentration
14% CP
12% CP + Lysine
10% CP + Lysine +
Threonine + Tryptophan
+ Methionine
N Balance
N intake, g/d
67
58
50
N digested and absorbed, g/d
60
51
43
N excreted in feces, g/d
7
7
7
N retained, g/d
26
26
26
N excreted in urine, g/d
34
25
17
N excreted, total, g/d
41
32
24
Reduction in N excretion, %
—
22
41
Change in dietary costs, $/tonb
0
-0.35
+$14.50
" Assumes an intake of 6.6 lb/d and a growth rate of 1.98 lb/d. b Costs used L-Lysine HC1, $2.00/lb; corn, $2.50/bushel; SBM, $250/ton; L-
Threonine, $3.50/lb; DL-Methionine, $1.65/lb; Tryptosine (70:15, Lys: Tryp) $4.70/lb.
Source: as presented in NCSU, 1998.
Although it is currently cost-effective to use supplemental lysine and methionine (Table 9-15), supplemental
threonine and tryptophan are currently too expensive to use in practical diets. However, because of the rapid
technological advances in fermentation procedures for synthesizing amino acids, threonine and tryptophan will likely
become sufficiently inexpensive in the next few years for use in practical diets.
Phase feeding and split-sex feeding. Dividing the growth period into more phases with less spread in weight allows
producers to more closely meet the pig's protein requirements. Also, since gilts (females) require more protein than
barrows (males), penning barrows separate from gilts allows lower protein levels to be fed to barrows without
9-11
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compromising leanness and performance efficiency in gilts. Feeding three or four diets during the grow-finish period
compared with feeding only two diets during that phase would reduce nitrogen excretion by at least 5 to 8 percent.
Formulate diets on an available phosphorus basis. A high proportion (56 to 81 percent) of the phosphorus in
cereal grains and oilseed meals occurs as phytate. Phosphorus in this form is not well utilized by pigs because they
lack intestinal phytase, the enzyme needed to remove the phosphate groups from the phytate molecule. Therefore,
supplemental phosphorus is added to the diet to meet the pig's growth requirements, but excessive phosphorus is
excreted in the urine, increasing manure phosphorus concentrations.
Because some feedstuffs are high in phytate, and because there is some endogenous phytase in certain small grains
(wheat, rye, triticate, barley), there is wide variation in the bioavailability of phosphorus in feed ingredients. For
example, only 12 percent of the total phosphorus in corn is available while 50 percent of the total phosphorus in
wheat is available. The phosphorus in dehulled soybean meal is more available than the phosphorus in cottonseed
meal (23 vs. 1 percent), but neither source of phosphorus is as highly available as the phosphorus in meat and bone
meal (66 percent), fish meal (93 percent), or dicalcium phosphate (100 percent).
Supplementing diets with phytase enzyme. Supplementing the diet with the enzyme phytase is an effective means
of increasing the breakdown of phytate phosphorus in the digestive tract and reducing the phosphorus excretion in
the feces. Using phytase allows one to feed a lower phosphorus diet because the unavailable phytate phosphorus in
the grain and soybean meal is made available by the phytase enzyme to help meet the pig's phosphorus needs.
Studies at Purdue University, at the University of Kentucky, and in Denmark indicate that the inclusion of phytase
increased the availability of phosphorus in a corn-soy diet by threefold, from 15 percent up to 45 percent.
A theoretical example of using phytase follows (Table 9-16). If a finishing pig is fed a diet with 0.4 percent
phosphorus (the requirement estimated by NRC, 1988, cited in NCSU, 1998), 12 g of phosphorus would be
consumed daily (3,000 x 0.4 percent), 4.5 g of phosphorus would be retained, and 7.5 g of phosphorus would be
excreted. Feeding a higher level of phosphorus (0.5, 0.6 or 0.7 percent) results in a slight increase in phosphorus
retention, but causes considerably greater excretion of phosphorus (10.3, 13.2, and 16.2 g/d, respectively). Being
able to reduce the phosphorus to 0.3 percent in a diet supplemented with phytase would reduce the intake to 9 g of
phosphorus per day and would potentially reduce the excreted phosphorus to 4.5 g/day (a 37 percent reduction in
phosphorus excretion vs. NRC). The percent reduction in excreted phosphorus is even more dramatic (56 percent)
when one compares the 4.5 g with the 10.3 g of phosphorus that is excreted daily by finishing pigs fed at the 0.5
percent phosphorus level typically being recommended by universities and feed companies. Bone strength can be
completely recovered by supplementing a low-P diet with 1,000 phytase units/kg of feed, while most of the grain and
feed efficiency is returned to NRC levels. In addition to returning bone strength and growth performance to control
levels, there is a 32 percent reduction in phosphorus excretion. A summary of 11 experiments (Table 9-17) indicates
that all the growth rate and feed efficiency can be recovered with the dietary supplementation of 500 phytase units
and reduced phosphorus diets. Some analyses have suggested that a 50 percent reduction in excreted phosphorus by
pigs would mean that land requirements for manure applications based on phosphorus crop uptake would be
comparable to manure applications based on nitrogen.
Table 9-16. Theoretical model of effects of dietary phosphorus level and
phytase supplementation (200-lb pig).
Dietary P (%)
Phosphorus (g/d)
Change From Industry
Average (%)
Intake
Retained
Excreted
0.70
21.0
4.8
16.2
+57
0.60
18.0
4.8
13.2
+32
0.50
15.0
4.7
10.3
0
0.40 (NRC, 1988)
12.0
4.5
7.5
-27
0.30
9.0
2.5
6.5
-37
0.30 + Phvtase
9.0
4.5
4.5
-56
Source: Cromwell and Coffey, 1995, cited in NCSU, 1998.
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Table 9-17. Effect of microbial phytase on relative performance of pigs.a
Growth Response
Negative Control
Positive Control
Effect of 500+ Phytase
Units/kg
ADG
100
115 (+/- 6.5)
116.7 (+/-10.6)
ADFI
100
105 (+/- 5.2)
107.6 (+/- 7.8)
Feed Conversion Ratio
100
93 (+/- 4.9)
93.2 (+/- 5.0)
a Eleven experiments with the negative control diets set at 100% and the relative change in pig growth performance to the control diets.
Source: Jongbloed et al., 1996, cited in NCSU, 1998.
Previously, phytase was too expensive to use as a feed additive. However, this enzyme can now be effectively
produced by recombinant DNA techniques, and the cost has decreased. A cost evaluation can be performed by
replacing an inorganic phosphorus source like dicalcium phosphate in the diet with phytase. Current phytase prices
indicate that dietary phosphorus levels could be reduced by 0.1 percent and the phytase enzyme would be cost
neutral. However, if the dicalcium phosphate price were $0.15/lb instead of $0.20/lb, dietary phosphorus would
need to be reduced by 0.15 percent to be cost neutral. The pig requires that phytase supplementation be fed at
different levels based on the age of the pig (Table 9-18). The different levels based on phase of production likely
relate to the digestive enzyme and cecum development of the pig, the younger pig being less developed.
Table 9-18. Effect of microbial phytase on increase in phosphorus digestibility by age of pigs and the
recommended rates for inclusion of phytase in each phase.
Nursery
Grower
Finisher
Gestation
Lactation
Approximate
Increase (%)
13
17
17
7
20
Inclusion Level
(Phvtase Unit/lb)
454-385
385-227
27-113
227
227
Source: Jonbloed et al., 1996, cited in NCSU, 1998.
9.3.2 Waste Collection and Storage
Removal of manure from the animals' living space is critical for animal and farm worker well-being. Odor, gases,
and dust carried by ventilation exhaust air are also affected by the manure removal system. Slatted floors are
commonly used to separate the manure from hogs. Underfloor flushing or pit recharge systems are commonly used
with anaerobic lagoon systems.
Storage is a critical function of farm systems since manure nutrients can be applied to farmland only at certain times
of the year as determined by crops, climate, and weather. Deep pits and slurry basins have been used with slurry
systems. Storage capacity is one function served by anaerobic lagoons. Most hog farms have from 90 to 365 days of
storage capacity. Transport and land application of manure nutrients is necessary to realize the fertilizer benefit of
manure nutrients and to comply with nutrient management regulations designed to protect water quality. Surface
application and injection are common means of land application for slurry. Transport of slurry is by "umbilical"
hose and pump or by pump and haul in tanks. Transport and land application of anaerobic lagoon liquid is
commonly done through irrigation. Transport and land application of anaerobic lagoon sludge may be done by
irrigation or by pump and haul.
Water wash waste removal from swine houses. Typically, the floor surface in swine houses is slotted over manure
collection pits. Because animals work the manure through floor slots, manure is separated quickly from the animals
into the pits. Water wash systems, which recycle lagoon water, are used to remove wastes from the underfloor pits,
which are 2 to 3 feet deep. Pits can be washed once a day or even more frequently. The more frequently the manure
is removed from the houses, the more healthful the environment for both animals and workers.
Pit recharge. Pit recharge is the periodic draining of the pit contents by gravity to a lagoon, then recharging the pit
with new lagoon water. Regular pit draining removes much of the manure solids that would otherwise settle and
remain in the bottom of the pit. The regular dissolution of settled solids increases the likelihood the solids will be
removed at the next pit draining. Zero slope is specified for the pit floor in pit recharge systems, but a minimum
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slope of 1:20 is used for constructing the pit to overcome an uneven floor surface, which could result in incomplete
waste removal and associated problems. If the entire house is sloped, enough pit depth must exist to cover the upper
end of the pit floor with at least 6 inches of water, while allowing enough storage below the air plenum openings on
the lower end. The drains are located at the lower end of the pits, while the recharge locations are opposite the drain
outlets. An average depth of 12 inches of recharge water and another 12 inches for waste accumulation between pit
drainings is allowed. The maximum pit water level should be at least 4 inches below the air plenum openings or 12
inches below the slats. Generally, a 32-inch pit depth is the minimum between the slotted floor and pit floor. A
gutter across the drain end of the pit floor directs waste to an exterior collection box, which is connected to an
underground drainpipe leading to the lagoon. The pits are usually drained and recharged once a week.
This is the most common waste management system in the midwest. Specifically, these systems use a 16 to 18-inch-
deep in-house pit with 6 to 8 inches of precharge water, which is emptied every 7 days to a single anaerobic lagoon.
Previously, 24-inch deep pits were preferred, but now 16 to 18-inch-deep pits are used with the hog slat system.
Because of odor problems, there is a trend away from the earthen pond for solids separation to either a single
anaerobic lagoon or an anaerobic lagoon and an evaporation pond. These ponds are designed to remove 40 percent
of the total solids on a 6 percent solids basis for 3 month's storage; the material is pumped to another earthen pit,
which serves as a drying bed, or flow is diverted to a parallel solids removal pond. The slurry dries to about 38
percent solids and 3-inch thickness within 6 months. Material is then moved with a front-end loader into a box-type
spreader and land applied. Solids drying ponds and beds are not covered to prevent the introduction of rainfall. The
lagoon is based on 2 to 3 cubic feet per pound (ft 3/lb) and irrigation is through a center pivot system. A floating
pump is located half the lagoon distance from the inlet with a screen over the discharge to protect sprinkler nozzles.
The screen has to be cleaned, but this is easier than cleaning nozzles for traveling big guns. Another variation is to
have a single lagoon (based on 2 to 3 ft 3/lb) followed by an evaporation pond that is 6 ft deep and as big as possible.
Some of these evaporation ponds dry up during the summer.
One operation is installing a 16-inch-deep pit recharge system using 6 to 8 inches of precharge water and emptying it
every 7 days. The operator had been using an older NRCS lagoon criteria of about 1 ft 3/lb but has now increased
that to 2 ft3/lb because of odor problems. Lagoon design is 1 year of storage in addition to the treatment volume.
This type of a lagoon/center pivot irrigation system is more acceptable in states with a decreasing population density
and an established center pivot irrigation system, such as Oklahoma, Kansas, and Iowa. The operation is taking
advantage of the fertilizer value for corn. Future plans are to go beyond the 18-inch compact soil seal to synthetic
liners and plastic covers, both for existing earthen solids drying beds and anaerobic lagoons.
Flush. Flush systems use recycled lagoon water for frequent removal of feces and urine from underfloor collection
gutters or shallow pits. As with pit recharge systems, flush systems also improve animal health and performance as
well as human working conditions in the swine houses by avoiding prolonged storage of manure in the collection
pits. Flush tanks with the capacity to release at least 1.5 gallons per 100 pounds of live animal weight per flush are
adjacent to the end of the swine houses. Pit floors should be level from side to side, and wide pits should be divided
into individual channels no wider than 4 to 5 feet. The floor slope for most flush systems is between 1 to 2 percent.
Floors should be flushed at least 4 to 6 times per day. The flush tanks are filled with recycled lagoon water before
every flush. The flushed waste is collected and removed from the houses into the lagoon through a system similar to
that used in pit recharge systems.
Deep pits. Many farms use deep pits that are 6 to 8 feet deep for up to 6 months storage of under the house. Twice
a year a slurry is removed from the pit for surface application or subsurface injection, into an earthen storage facility,
or pumped to a steel aboveground storage tank. This material is valued for its nutrient content and is applied to
nearby land as fertilizer for corn and soybeans. Application is most often by surface spreading and tillage or by
direct injection. This slurry system produces a waste stream with higher dry matter content (4 to 5 percent) and
higher nutrient content than liquid manure systems. The aboveground storage system conserves more nitrogen than
other systems (nitrogen loss of 10 to 30 percent). In this system, nutrients average 4.3 g/L N, 1.4 g/L P, and 2.2 g/L
K (MWPS, 1985). Operations use this system to avoid problems associated with lagoons such as odor, ammonia
volatilization, and ground water impact.
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9.3.3 Anaerobic Lagoon Treatment
Treatment of manure to separate nutrients is economical in some situations when the cost of storing and hauling
manure slurry exceeds its potential value as a fertilizer. Treatment becomes more attractive as crop yields decrease
(and therefore land required for nutrient utilization increases). Treatment also becomes more attractive as hog farm
size increases. No treatment occurs in typical slurry systems. Anaerobic digestion is the primary treatment in
anaerobic lagoon systems. Plant-available nitrogen and phosphorus in land-applied anaerobic lagoon liquid may be
at 10 percent of the nutrient concentration in the flush water entering the lagoon. Much of the nitrogen in swine
manure is volatilized from the anaerobic lagoon or from the spray field. Much of the phosphorus in the manure
settles in the lagoon sludge and attaches to the lagoon walls and bottom. Once every 5 to 15 years, anaerobic lagoon
sludge can be applied to land other than the spray field receiving lagoon liquid. As a result, phosphorus is often
spread over a greater area than the reduced quantity of nitrogen that is applied to a smaller spray field.
Anaerobic lagoons are the most common means of swine manure treatment in the southeastern region. Anaerobic
bacteria, present in the intestinal tract of warm-blooded animals, can decompose more organic matter per unit lagoon
volume than aerobic bacteria. However, incomplete anaerobic decomposition of organics can result in offensive by-
products, primarily hydrogen sulfide, ammonia, and intermediate organic acids, which may cause disagreeable odors.
Therefore, proper size and management are necessary to operate an anaerobic lagoon. The minimum total capacity of
an anaerobic lagoon should include appropriate design treatment capacity, additional storage for sludge
accumulation, temporary storage for rainfall and wastewater inputs, surface storage for a 25-year, 24-hour design
rainfall event, and a freeboard, or indicator of the highest watermark, to prevent embankment overtopping. In North
Carolina, the recommendation is 2 cubic feet of liquid volume per pound of live animal weight for a single anaerobic
lagoon. A two-stage lagoon would have 1.5 cubic feet of volume per pound of live animal weight in the first stage
and 0.5 cubic foot of volume per pound of live animal weight in the second stage. It is suggested that a lagoon to be
located at least 1,000 feet from any residence or inhabited dwelling not owned by the producer. Lagoons should be
located on soils of low permeability or soils that seal through biological action or sedimentation, and proper liners
should be used to avoid ground water contamination.
New lagoons should be half filled with water before waste loading begins. Starting up during warm weather and
seeding with bottom sludge from a working lagoon will speed establishment of a stable bacterial population. Under
no circumstances should dead animals, molded feed, plastic gloves, long-stemmed vegetation, or other foreign
material be allowed to enter a lagoon. Proper lagoon maintenance and operation is absolutely necessary to ensure
that lagoon liner integrity is not affected and that berms and embankments are stable and provide the required
freeboards and rainfall storage.
Even when bacterial digestion is efficient, significant amounts of sludge accumulate in anaerobic lagoons. Although
lagoons can be designed with enough storage to minimize the frequency of bottom sludge removals, at some point
the treatment capacity of most lagoons will be diminished greatly as a result of accumulation. The method used most
frequently to remove sludge entails vigorous mixing of sludge and lagoon water by means of an agitator/chopper
pump or propeller agitator. The operation of the agitator/chopper for sludge removal must be continuously
monitored to ensure that liner damage does not occur or that berms or embankments are damaged, which could result
in contamination of surface or ground water. The sludge mixture is pumped through a gun-sprinkler slurry irrigation
system onto cropland and disked into the soil.
Lagoons usually fill to capacity within 2 to 3 years of startup due to the added waste volume and rainfall that is in
excess of evaporation. When the lagoon is full, water overflow will occur unless the operator is in a position to land
apply the excess water. Since no overflow is permitted, excess water needs to be applied to cropland, grassland, or
woodland at rates within the soil infiltration capacity and the fertilizer requirement of the vegetation. Sampling and
analysis of the lagoon water is suggested to determine its nutrient content. Many states require a nutrient
management program for which records regarding the amount of nitrogen applied to cropland must be kept to be sure
fertilizer recommendations are not exceeded. Lagoon water drawdown by irrigation should begin before the water
reaches the maximum wastewater storage level. Several states require that liquid level indicators be placed in the
lagoon to be sure that the liquid stays below the level required to contain the 24-hour, 25-year storm.
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9.4 Example Systems
There is also a trend toward consistency from one part of the country to another. The three-site model that separates
production phases is being adopted across the country, while finishing age and number of litters per year tends to be
the same from one part of the nation to another. With the exception of the Midwest, producers tend to farrow small
groups of sows weekly. In the Midwest, some producers farrow only twice a year, usually in the spring and fall.
This is usually done on smaller farms, where sows are maintained outdoors, then moved indoors for farrowing. Pigs
are also finished in confinement. Of course, the buildings in which pigs are housed in the Midwest tend to differ
from those in more temperate parts of the country, and waste is managed differently in the Midwest than in other
parts of the country.
Confined, three-site operations predominate in the Southeast, South-Central, and West Regions, although there are
some smaller outdoor operations in the South-Central and West Regions. In the Midwest and New England, the
number of outdoor and confinement operations is roughly the same, but there are far more hogs raised in
confinement operations.
Most types of waste management systems are similar across all regions with only minor deviations. For example, the
pit recharge systems with aboveground storage and land application are nearly identical among farms in the
Midwest, South-Central, and Northeast Regions. The primary waste management system that has the most variation
among and within regions is that described as the hand wash system. Hand wash systems are found predominantly
on operations with fewer than 500 pigs; most of the operations using hand washing as their primary waste
management system have fewer than 100 pigs. On these operations, it is in the farrowing house and/or nursery
phases of production in which hand washing is used to remove fecal material and urine from the buildings. For units
using hand washing, the wash water either exits the building and enters the environment directly or a collection basin
is located underneath or at one end of the building. In the case of collection, the wash water is stored and used for
land application at a later time or is allowed to evaporate over time. Frequency of hand washing may vary among
operations from three times per day to once per week.
Another type of system identified as a primary waste management system on small operations in the Midwest and
New England (NAHMS, 1995 and 1996) uses a flat blade on the back of a tractor to scrape or remove manure from
feeding floors. The popularity of this system apparently has decreased over the last 3 years, and the system no
longer represents a major avenue for removing wastes from swine feeding locations.
9.4.1 Systems in Alaska, California, Hawaii, Idaho, Montana, Nevada, Oregon, and Washington
Descriptive information about the number of pigs and types of operations in these states is contained in Table 9-19.
These states contain 6.0 percent and 0.9 percent of the swine farms and total pigs in the United States, respectively.
California and Montana account for 71 percent of the production within these states and are the only two states with
significant numbers of farms with more than 2,000 animals. In general, these states are primarily composed of farms
with fewer than 500 pigs (93 percent) that use hand washing and dry lots as their primary waste management system.
In contrast, the majority of pigs (56.6 percent) are produced on farms with 500 to 2,000 animals that use either hand
washing/dry lots or deep pit/aboveground storage/land application for reincorporation of swine waste back into the
environment.
9.4.2 Systems in Arkansas, Arizona, New Mexico, Oklahoma, Texas, and Utah
Table 9-20 present information for Arkansas, Arizona, New Mexico, Oklahoma, Texas, and Utah which contain 10.2
percent and 5.9 percent of the swine farms and total pigs in the United States, respectively. Five of the six states
have experienced a net increase in the number of pigs and large farms (more than 2,000 head) during the past 5
years. This area also accounts for the fastest growing area of swine production in the nation at the present time. As a
result, the majority of the farms (53.3 percent) in these states contain more than 2,000 head and contain 90 percent of
the pigs. As a group, these large farms seem to rely on aeration of anaerobic lagoons, biogas production from
lagoons, or evaporation from lagoons as the main ways to treat swine waste and reincorporate it back into the
environment.
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Table 9-19. Distribution of pigs and predominant waste systems by farm size in Alaska,
California, Hawaii, Idaho, Montana, Nevada, Oregon, and Washington.
Farm Size
(number of pigs)
Number of
Farms
Percent of Farms
Percent of Pigs
Primary Waste
Management System
Fewer than 500
7,524
93.0
11.4
1. Hand Wash/Dry Lots
2. Scraper/Aboveground
Storage/Land Application
500 to 2,000
485
6.0
56.6
1. Hand Wash/Dry Lots
2. Deep Pit/Aboveground
Storage/Land Application
More than 2,000
81
1.0
32.0
1. Deep Pit/Aboveground
Storage/Land Application
2. Pit Recharge/Covered
Anaerobic Lagoon/Irrigation
Total
8,090
Source: as presented in NCSU, 1998.
Table 9-20. Distribution of pigs and predominant waste systems by farm size in
Arkansas, Arizona, New Mexico, Oklahoma, Texas, and Utah.
Farm Size
Percent of
Primary Waste
(number of pigs)
Number of Farms
Farms
Percent of Pigs
Management System
Fewer than 500
4,022
28.5
0.8
1. Hand Wash/Dry Lots
500 to 2,000
2,563
18.2
9.2
1. Flush or Pit Recharge/Anaerobic
Lagoon/Irrigation
2. Deep Pit/Aboveground
Storage/Land Application
More than 2,000
7,515
53.3
90.0
1. Flush or Pit Recharge/Aeration of
Anaerobic Lagoon/Irrigation
2. Flush or Pit Recharge/Covered
Anaerobic Lagoon/Land Application
3. Pit Recharge/Evaporation from
Two-Stage Lagoon System
Total
14,100
Source: as presented in NCSU, 1998.
Utah swine production. Circle 4 is the primary integrator in Utah. These operations use a pit-recharge system
(depth of pit and volume of recharge water are unknown at this time) that is emptied about 3 times per week.
Wastewater treatment is by a two-stage evaporative lagoon system. The primary stage is designed for treatment of
volatile solids with additional volume for 20 years of sludge storage. Exact treatment volume design is farm- (or
complex-) specific and includes consideration of diet, feed digestibility, and absorption and conversion efficiency of
the animal. The primary stage is sized on the basis of volume per volatile solids input plus an additional volume for
20 years of sludge storage. The secondary stage lagoon volume and surface area are specified to allow evaporation
of all excess water not required for pit recharge.
Waste management plans call for sludge removal on the order of 20 years. Land for agronomic application of
biosolids is not required to be under the direct control of the farm owner/operator. No operation has reached its
design life at this time to evaluate this procedure.
9.4.3 Systems in Connecticut, Delaware, Maryland, Massachusetts, Maine, New Hampshire, New Jersey,
New York, Pennsylvania, Rhode Island, Vermont, and West Virginia
Table 9-21 summarizes descriptive information for Connecticut, Delaware, Maryland, Massachusetts, Maine, New
Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and West Virginia which contain 8
percent and 0.2 percent of the swine farms and total pigs in the United States, respectively. Of these states,
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Pennsylvania contains about 80 percent of the pigs and farms. It also contains the vast majority of the large-and-
medium-size units. The medium and large farms rely on either anaerobic lagoons and irrigation or aboveground
storage and land application as their primary means of waste management. Farms in the remaining 11 states
typically have fewer than 500 animals each. Small operations constitute 57.8 percent of all farms in these states and
use hand washing in conjunction with drylots as their primary waste management system.
Table 9-21. Distribution of pigs and predominant waste systems by farm size in Connecticut,
Delaware, Maryland, Massachusetts, Maine, New Hampshire, New Jersey, New York,
Pennsylvania, Rhode Island, Vermont, and West Virginia.
Farm Size
Number of
Percent of
Percent of
Primary Waste
(number of pigs)
Farms
Farms
Pigs
Management System
Less than 500
6,390
57.8
3.7
1. Hand Wash/Dry Lots
2. Gravity Drain/Collection
Basin/Land Application
500 to 2,000
2,297
20.8
40.6
1 Deep Pit/Aboveground
Storage/Land Application
2. Pit Recharge/Anaerobic
Lagoons/Irrigation
3. Scraper/Aboveground
Storage/Land Application
More than 2,000
2,363
21.4
55.7
1 Deep Pit/Aboveground
Storage/Land Application
2. Pit Recharge/Anaerobic
Lagoons/Irrigation
Total
11,050
Source: as presented in NCSU, 1998.
The design and operation of the anaerobic lagoon and irrigation system are very similar to those of the system used
in the southeast; however, there are some notable differences. Lagoon loading rates must be lowered to
accommodate the lower temperatures of the region and storage requirements must be increased to accommodate the
longer inactive period during winter. Although average yearly rainfall is about the same in the two regions, rainfall
in excess of evapotranspiration is higher in these states, further increasing storage requirements. Emergency storage
for the 25-year, 24-hour storm event is lower in these states than in the southeast. Design and operation of the
above-ground storage/land application system are similar to those used in the Midwest. The primary difference is
the site-specific realistic yield expectation of the fields accepting the nutrients. Differences in crop production
techniques must also be considered.
9.4.4 Systems in Alabama, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South
Carolina, Tennessee, and Virginia
Table 9-22 summarizes descriptive information for Alabama, Florida, Georgia, Kentucky, Louisiana, Mississippi,
North Carolina, South Carolina, Tennessee, and Virginia which contains 17.7 percent and 21.3 percent of the swine
farms and total pigs in the United States, respectively. Large operations (more than 2,000 head) represent 63.4
percent of the farms in these states and produce 92.5 percent of the pigs. North Carolina contains the largest number
of farms with more than 2,000 animals and 77.1 percent of the region's production. The predominant waste
management system is a flush or pit-recharge system for removal of waste from buildings, an anaerobic lagoon for
treatment and storage of waste, and reincorporation of treated waste back into the environment by irrigation. In these
states, housing is usually enclosed with ventilation and concrete floor surface. A typical waste management practice
for swine production farms includes a water wash system to remove wastes from swine houses, an anaerobic lagoon
to treat the wastes, and a cropland irrigation system to use the nutrients in the lagoon water.
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Table 9-22. Distribution of pigs and predominant waste systems by farm size in Alabama, Florida, Georgia,
Farm Size
(number of pigs)
Number of
Farms
Percent of
Farms
Percent of
Pigs
Primary Waste Management System
Less than 500
4,199
16.9
0.9
1. Hand Wash/Dry Lots
2. Scraper System/ Aboveground
Storage/Land Application
500 to 2,000
3,883
15.9
6.6
1. Flush or Pit Recharge/Anaerobic
Lagoon/Irrigation
More than 2,000
16,268
63.4
92.5
1. Flush or Pit Recharge/Anaerobic
Lagoon/Irrigation
Total
24,350
Source: as presented in NCSU, 1998.
9.4.5 Systems in Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota,
Ohio, South Dakota, and Wisconsin
Table 9-23 summarizes descriptive information for Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri,
Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin which contains 58.2 percent and 69.8 percent of the
swine farms and total pigs in the United States, respectively. Numbers of small, medium, and large farms are fairly
evenly distributed in this region. However, recent construction of large units in Iowa, Minnesota, Missouri, and
South Dakota indicate that the trend toward production in larger units, as seen in the southeastern United States, is
probably increasing in the Midwest. Primary waste management systems for farms with fewer than 500 pigs are
hand wash coupled with drylots with and without collection basins. In contrast, medium and large farms rely on
storage of waste either in buildings with deep pits or in above-ground structures in conjunction with direct land
application for crop production.
Table 9-23. Distribution of pigs and predominant waste systems by farm size in Illinois, Indiana, Iowa,
Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin.
Farm Size
(number of pigs)
Number of
Farms
Percent of
Farms
Percent
of Pigs
Primary Waste Management System
Less than 500
23,693
29.5
2.7
1. Hand Wash/Dry Lots
2. Hand Wash/Dry Lots and Collection Basin/Land
Application
3. Deep Pit/Land Application
500 to 2,000
22,334
27.8
18.1
1. Deep Pit/Aboveground Storage/Land Application
2. Pit Recharge/Aeration of Anaerobic
Lagoons/Irrigation
3. Deep Pit/Land Application
More than 2,000
34,273
42.7
79.8
1. Deep Pit/Aboveground Storage/Land Application
2. Pit Recharge/Covered Anaerobic
Lagoon/Irrigation
Total
80,300
Source: as presented in NCSU, 1998.
9.5 Example System Costs
This section summarizes the basic costs associated with a water flush/lagoon/spray field system in the southeast and
a deep pit storage system in the Midwest (Table 9-24). The details of assumptions are presented recognizing that
site-specific conditions could substantively change the results.
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Table 9-24. Sample costs and benefits of typical manure management systems.
Category
Slurry (Midwestern) System ($/hog
finished)
Anaerobic Lagoon (Southeastern)
System ($/hog finished)
Storage, Treatment
$1.69
$0.42
Transport, Land Application
$1,164
$0,514
Sludge Removal, Land Application
NA
$0.05 to $0.90
Reduced Crop Income on Spray Field
and Land Cost
NA
$0,121
Value of Fertilizer Saved
$2,438
NA
Net Cost
$0,416
$1.10 to $2.00
9.5.1 Water Flush/Lagoon/Spray Field System in the Southeast
Gravity flow in conjunction with slatted floors provides the mechanism for manure removal from the majority of
southeastern swine facilities. A lagoon typically provides liquid and sludge storage for treatment by an anaerobic
lagoon system. The excavated volume of the lagoon is 1.5 cubic feet per pound steady-state live weight or 810,000
cubic feet. Excavation and other costs are $1.10 per cubic yard. Total construction cost of the lagoon is $33,000.
Annual ownership costs of the lagoon are $4,350 or $0.42 per hog finished.
Costs of lagoon liquid irrigation are estimated at $41.13 per acre-inch (0.001515 per gallon) for 130 acre-inches per
year and an annual cost of $5,347. This equates to an irrigation cost of $0.514 per finished hog. Benefits of the
water flush-anaerobic lagoon system include the value of fertilizer saved and application costs reduced compared to
other systems. Income from crops cultivated on spray fields is diminished if the farmer plants a less profitable crop
that uses higher levels of nitrogen. For example, a spray field of bermudagrass will result in a lost income that
equals the difference between the most profitable crop or rotation and the income actually received from the benefit
of bermudagrass and the net savings on fertilizer costs. Irrigation provides 330 and 90 lb/acre of nitrogen and
phosphorus, respectively with an estimated value of $30.75 per acre. Considering the rental value of land occupied
by the lagoon, the total cost for water flushing to an unaerated lagoon followed by land irrigation to coastal
bermudagrass is $1.10 per finished hog.
Costs of removing sludge from the anaerobic lagoon depend heavily on the accumulation rate, the frequency of
removal, the method of removal, and the distance transported. The lowest cost of sludge removal occurs if the
sludge accumulates slowly, is removed after 15 years, and is removed by irrigation of sludge diluted 1:1 with lagoon
liquid. The highest cost occurs when sludge accumulates quickly, is removed every 5 years, is removed by pump
and haul, and is hauled more than 3 miles.
9.5.2 Deep Pit Storage System in the Midwest
This cost analysis is based on a typical midwestern waste system that allows for 6 months of storage of manure in the
house and land application by direct injection. The system considered here is sized to serve a finishing pig operation
with a 4,000-head one-time capacity. Manure removal is via slatted floors and gravity flow. The volume of manure
and other water falling through the slats each day is 1.44 gallons per hog. Storage is in a concrete tank with a
capacity of 180 days or 1,037,000 gallons or 138,356 cubic feet plus 10,643 cubic feet for a 1-foot freeboard.
Construction cost is estimated at $113,633 including all excavation, concrete, labor, and plumbing. Amortized over
15 years at 8 percent (APR) and including 1.5 percent annually for property tax and insurance, the annual cost of
owning the concrete tank is $17,617. Assuming a 4,000-head capacity and 2.6 groups finished peryear, the cost per
finished hog is $1.69.
Transport and land application are by pump, umbilical line and tractor-drawn injection for the slurry system. Custom
rates for the slurry pump and injection system are $0.0071 per gallon plus $0.0028 per gallon per mile for distances
greater than 1 mile. It is estimated that 563 acres of 120 bushel per acre corn land is needed to receive the annual
slurry production for this operation. (This analysis assumes 144 lb nitrogen per acre, 47.5 plant-available nitrogen
per 1,000 gallons of injected slurry, and 164 gallons slurry per hog finished). If this land area is available within 1
mile of the storage tank, the pumping and injection costs will be $1,164 per hog finished.
9-20
-------
Benefits of the slurry system include the value of fertilizer saved. If the slurry provides all the fertilizer required by
the crop, the cost of an application may also be saved. The 164 gallons of slurry applied to 120 bushels per acre
continuous corn replaces $2.127 of fertilizer and may save $0,311 per hog finished in fertilizer application costs for
a benefit of $2,438 per hog finished.
Net cost is the sum of cost less benefits. In this example, the cost of the slurry system on 120 bushel per acre corn
land is less than the cost of the anaerobic lagoon system on less productive land producing bermudagrass.
Considering a deep pit for up to 6 months storage of manure followed by land application by direct injection, a total
cost of $0.41 per finished hog is accrued.
9.6 Bibliography
APHIS. 1995. Swine '95 Part I: Reference of 1995 Swine Management Practices.
. File sw95desl.pdf accessed October 15, 1998. U.S.
Department of Agriculture, Animal and Plant Health Inspection Service.
APHIS. 1996. Swine '95 Part II: Reference of 1995 Grower/Finisher Health and Management.
. File sw95des2.pdf accessed October 15, 1998. U.S.
Department of Agriculture, Animal and Plant Health Inspection Service.
Lander, C.H., D. Moffitt, and K. Alt. 1998. Nutrients Available from Livestock Manure Relative to Crop Growth
Requirements. U.S. Department of Agriculture, Natural Resources Conservation Service, Resource
Assessment and Strategic Planning Working Paper 98-1. . Accessed October 15, 1998.
NASS. 1998. Agricultural Statistics 1998. . File 98_ch7.pdf
accessed October 19, 1998.
NCSU. 1998. Draft of Swine and Poultry Industry Characterization, Waste Management Practices andModel
Detailed Analysis of Predominantly Used Systems. North Carolina State University, Raleigh, North
Carolina. September.
9-21
-------
10.0 Poultry4
10.1 Introduction
This chapter summarizes the demographics and waste management practices associated with broilers, layers, and
turkeys.
10.2 Demographics
10.2.1 Broilers
Broiler production in the United States has steadily increased over the last decade (Table 10-1). Between 1987 and
1996, the number of broilers has increased by 52 percent, from approximately 5 billion to 7.6 billion.
Accompanying the increased number of broilers, is an increase average live weight at slaughter from 4.3 to 4.8
pounds. Together these changes have yielded nearly a 70 (69.5) percent increase in live weight of broilers produced
since 1987.
Table 10-1. Broiler production in the United States, 1987-96.a
Year
Number raised
(thousands)
Pounds produced
(live weight,
1,000 pounds)
1987
5,003,560
21,523,356
1988
5,237,901
22,464,479
1989
5,516,521
23,978,816
1990
5,864,150
25,630,960
1991
6,137,150
27,202,862
1992
6,402,490
28,828,872
1993
6,694,310
30,617,600
1994
7,017,540
32,528,500
1995
7,325,670
34,222,000
1996b
7.598.200
36.486.050
a Broilers are young chickens of the meat-type breeds, raised for the purpose of meat production.
Estimates cover the 12-month period, Dec. 1 previous year through Nov. 30. Excludes states that
produce fewer than 500,000 broilers. b Preliminary.
Source: NASS, 1998.
Table 10-2 displays broiler production by state for 1995 and 1996. The top five states in number of broilers raised in
1996 are Arkansas (1.155 billion), Georgia (1.154 billion), Alabama (873 million), North Carolina (681 million),
and Mississippi (676 million). Texas, Maryland, Virginia, Delaware, and Missouri are ranked sixth through tenth in
broiler production, respectively.
Figure 10-1 displays the number of broilers per county, and Figure 10-2 displays the number of operations per
county with 200,000 or more broilers sold. Table 10-3 presents the number of broiler operations by size class and
region. There are 9,214 operations (25.8 percent) that range in size from 25 to 100 animal units (11,400 to 45,500
broiler capacity), 7,319 operations (20.5 percent) that range in size from 100 to 300 animal units (45,500 to 136,500
broiler capacity), and 707 operations (2 percent) that are larger than 300 animal units (136,500 broiler capacity).
4 Sections 10.3 and 10.4 of this chapter are an abridged version of Chapters 5 through 8 of Draft Swine and Poultry Industry
Characterization, Waste Management Practices and Model Detailed Analysis of Predominantly Used Systems, prepared by North Carolina State
University on September 30, 1998, under EPA Contract 68-C7-0014, Work Assignment 1-27.
10-1
-------
Table 10-2. Broiler production by state, 1995 and 1996.a
1995
1996"
Pounds Produced
Pounds Produced
State
Number Raised
(thousands)
(live weight,
1,000 pounds)
Number Raised
(thousands)
(live weight
1,000 pounds)
Alabama
900,000
4,230,000
873,300
4,191,800
Arkansas
1,107,300
4,982,900
1,155,000
5,659,500
California
235,800
1,179,000
234,200
1,171,000
Delaware
263,100
1,394,400
257,600
1,416,800
Florida
139,800
615,100
131,400
591,300
Georgia
1,070,000
5,136,000
1,154,000
5,654,600
Hawaii
940
3,800
950
4,000
Iowa
15,000
72,000
17,200
77,400
Kentucky
64,500
258,000
77,000
331,100
Maryland
295,700
1,360,200
294,800
1,385,600
Michigan
630
2,850
550
2,200
Minnesota
48,000
249,600
47,500
251,800
Mississippi
644,000
2,962,400
675,900
3,109,100
Missouri
190,600
800,500
246,300
1,059,100
Nebraska
2,900
18,600
2,300
13,300
New York
1,400
6,900
1,500
8,000
North Carolina
670,100
3,417,500
681,100
3,541,700
Ohio
43,000
215,000
48,600
243,000
Oklahoma
198,300
852,700
204,000
877,200
Oregon
21,100
105,500
21,300
106,500
Pennsylvania
121,400
607,000
128,200
653,800
South Carolina
162,000
680,400
177,500
786,300
Tennessee
130,000
572,000
134,000
603,000
Texas
395,200
1,746,800
419,200
1,886,400
Virginia
260,100
1,196,500
259,100
1,243,700
Washington
40,300
197,500
40,000
196,000
West Virginia
88,900
391,200
89,700
394,700
Wisconsin
22,200
104,300
32,400
152,300
Other statesc
193.400
863.350
193.600
874.850
Total
7.325.670
34,222,000
7,598,200
36,486,050
a Broilers are young chickens of the meat-type breeds, raised for the purpose of meat production. Estimates cover the 12-month period,
Dec. 1 previous year through Nov. 30. Excludes states that produce fewer than 500,000 broilers. b Preliminary. c CT, IL, IN, LA, ND,
mid SD.
Source: NASS, 1998.
10-2
-------
Table 10-3. Distribution of broiler operations derived from
data collected in the 1992 Census of Agriculture.
Location
ODerations Categorized bv Size Class (animal units3)
1-25
25-100
100-300
300-500
500-
1,000
1,000-
5,000
5,000-
10,000
10,000 or
More
Total
Northeast
2,384
(50.8%)
1,358
(28.9%)
878
(18.7%)
58
(1.2%)
12
(0.3%)
1
(0.0%)
1
(0.0%)
0
(0.0%)
4,692
(13.1%)
Southeast
2,739
(22.8%)
4,632
(38.6%)
4,283
(35.7%)
280
(2.3%)
70
(0.6%)
8
(0.1%)
0
(0.0%)
0
(0.0%)
12,012
(33.6%)
North-Central
8,541
(93.5%)
330
(3.6%)
246
(2.7%)
18
(0.2%)
1
(0.0%)
3
(0.0%)
0
(0.0%)
0
(0.0%)
9,139
(25.6%)
South-Central
2,223
(31.6%)
2,806
(39.9%)
1,817
(25.9%)
142
(2.0%)
35
(0.5%)
3
(0.0%)
1
(0.0%)
1
(0.0%)
7,028
(19.7%)
Mountain
1,275
(99.9%)
0
(0.0%)
1
(0.1%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
1,276
(3.6%)
West
1,306
(83.9%)
87
(5.6%)
91
(5.8%)
33
(2.1%)
35
(2.2%)
3
(0.2%)
0
(0.0%)
2
(0.1%)
1,557
(4.4%)
Other
51
(92.7%)
1
(1.8%)
3
(5.5%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
55
(0.2%)
United States
18,519
9,214
7,319
531
153
18
2
3
35,759
a The procedure for estimating animal units was adopted from Lander et al. (1998).
10.2.2 Turkeys
The turkey industry is substantially smaller than the broiler industry in the United States, but it has undergone a 25
percent increase in number of turkeys raised in the last decade (Table 10-4). The average live weight at slaughter
also increased from 20.4 to 23.8 pounds, yielding an increase of 46.5 percent in total live weight production. Table
10-5 displays turkey production by state for 1996. The top five states in number of turkeys raised in 1996 are North
Carolina (59.5 million), Minnesota (43.5 million), Arkansas (28 million), Virginia (25 million), and California (22.5
million). Figure 10-3 displays the number of turkeys per county, and Figure 10-4 displays the number of operations
per county with turkeys.
Table 10-4. Turkey production in the United States, 1987-96.
Year
Number Raised3
(thousands)
Pounds Produced
(live weight,
1,000 pounds)
1987
240,438
4,894,858
1988
242,421
5,059,056
1989
261,394
5,467,629
1990
282,475
6,043,155
1991
284,910
6,114,620
1992
289,880
6,355,293
1993
287,650
6,432,577
1994
286,605
6,540,887
1995
292,856
6,779,277
1996b
301.378
7.171.527
" Total poults hatched less death loss of poults and young turkeys during the year. b Preliminary.
Source: NASS, 1998.
10-7
-------
Table 10-5. Turkey production by state, 1996/
State
Number Raisedb
(thousands)
Pounds Produced
(live weight,
1,000 pounds)
Arkansas
28,000
526,400
California
22,500
492,750
Colorado
4,800
179,040
Connecticut
8
152
Georgia
550
16,995
Illinois
3,300
78,870
Indiana
14,000
351,400
Iowa
8,000
221,600
Kansas
1,750
49,000
Maryland & Delaware
330
6,653
Massachusetts
80
1,600
Minnesota
43,500
948,300
Missouri
22,000
578,600
New Hampshire
15
300
New Jersey
73
1,650
New York
520
12,792
North Carolina
59,500
1,457,750
North Dakota
2,100
46,200
Ohio
6,800
227,120
Pennsylvania
11,700
245,700
South Carolina
8,300
256,470
South Dakota
3,000
96,000
Vermont
35
630
Virginia
25,000
475,000
West Virginia
4,500
85,500
Other statesc
31,017
815,055
Total
301,378
7,171,527
Preliminary b Based on turkeys placed Aug. 1, 1992, through, Jul. 31, 1993. Excludes young turkeys
lost. c MI, NE, OK, OR, TX, UT, and WI combined to avoid disclosing individual operations.
Source: NASS, 1998.
Table 10-6 presents the number of turkey operations by size class and region. There are 12,525 operations (80.3
percent) that are smaller than 100 animal units (5,000 breeders or 6,700 turkeys for slaughter capacity), 1,128
operations (7.2 percent) that range in size from 100 to 300 animal units (5,000 to 15,000 breeders or 6,700 to 20,100
turkeys for slaughter capacity), 1,576 operations (10.1 percent) that range in size from 300 to 1,000 animal units
(15,000 to 50,000 breeders or 20,100 to 67,000 turkeys for slaughter capacity), and 362 operations (2.3 percent) that
are larger than 1,000 animal units (50,000 breeders or 67,000 turkeys for slaughter capacity).
10-8
-------
Table 10-6. Distribution of turkey operations derived from
data collected in the 1992 Census of Agriculture.
Location
ODerations Categorized bv Size Class (animal units3
1-25
25-100
100-300
300-500
500-
1,000
1,000-
5,000
5,000-
10,000
10,000 or
More
Total
Northeast
2,027
(89.6%)
46
(2.0%)
91
(4.0%)
52
(2.3%)
30
(1.3%)
16
(0.7%)
0
(0.0%)
0
(0.0%)
2,262
(14.5%)
Southeast
2,107
(66.4%)
32
(1.0%)
334
(10.5%)
318
(10.0%)
293
(9.2%)
87
(2.7%)
0
(0.0%)
1
(0.0%)
3,172
(20.3%)
North-Central
4,186
(75.6%)
159
(2.9%)
494
(8.9%)
299
(5.4%)
269
(4.9%)
124
(2.2%)
3
(0.1%)
5
(0.1%)
5,539
(35.5%)
South-Central
1,634
(80.0%)
10
(0.5%)
138
(6.8%)
104
(5.1%)
107
(5.2%)
48
(2.3%)
2
(0.1%)
0
(0.0%)
2,043
(13.1%)
Mountain
1,129
(92.8%)
14
(1.2%)
28
(2.3%)
18
(1.5%)
21
(1.7%)
6
(0.5%)
0
(0.0%)
1
(0.1%)
1,217
(7.8%)
West
1,142
(85.7%)
13
(1.0%)
43
(3.2%)
19
(1.4%)
46
(3.5%)
63
(4.7%)
5
(0.4%)
1
(0.1%)
1,332
(8.5%)
Other
26
(100.0%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
26
(0.2%)
United States
12,251
274
1,128
810
766
344
10
8
15,591
a The procedure for estimating animal units was adopted from Lander et al. (1998).
10.2.3 Layers
Table 10-7 presents the number of layers and pullets in the United States from 1988 to 1997 (excluding broiler
breeding stock). Since 1988 there has been a 12.7 percent increase in layers and a 13.8 percent increase in pullets.
Table 10-8 presents the number of layer operations by size class and region. There are 84,076 operations (92.4
percent) that are smaller than 25 animal units (6,250 layers), 4,489 operations (4.9 percent) that range in size from
25 to 100 animal units (6,250 to 25,000 layers), 1,649 operations (1.8 percent) that range in size from 100 to 300
animal units (25,000 to 75,000 layers), and 826 operations (0.9 percent) that are larger than 300 animal units (75,000
layers). Figure 10-5 displays the number of hens and pullets per county, and Figure 10-6 displays the number of
operations per county with 50,000 or more hens and pullets of laying age.
Layers and pullets are distributed across the country with less regional concentration than broilers (Table 10-9).
California produces the greatest number of layers older than 1 year (15.27 million), followed by Iowa (11.66 million)
and Ohio (10.86 million). The top three pullet-producing states are Arizona (3.49 million), Ohio (3.4 million), and
Georgia (3.12 million). The top three egg-producing states are Ohio (6.98 billion), California (6.66 billion), and
Pennsylvania (5.79 billion).
10-13
-------
Table 10-7. Layer and pullet production in the United States, 1988-97.a
Year
Layers
Pullets
Older than
1 Year
(thousands)
20 Weeks to
1 Year Old
(thousands)
13 to 20 Weeks
Old
(thousands)
Under 13
Weeks Old
(thousands)
1988
123,435
152,714
33,739
40,859
1989
118,839
153,230
35,769
43,415
1990
119,551
153,916
34,222
38,945
1991
117,178
162,943
34,272
42,344
1992
121,103
163,397
34,710
45,160
1993
131,688
158,938
33,833
47,941
1994
135,091
163,418
32,805
45,146
1995
133,537
165,216
32,786
45,446
1996
137,822
165,932
31,366
44,611
1997b
140.686
170.398
34.174
50.693
" Does not include commercial broilers. b Preliminary.
Source: NASS, 1998.
Table 10-8. Distribution of layer operations derived from
data collected in the 1992 Census of Agriculture.
Location
Operations Categorized by Size Class (animal units3)
1-25
25-100
100-300
300-500
500-
1,000
1,000-
5,000
5,000-
10,000
10,000 or
More
Total
Northeast
10,988
(93.0%)
391
(3.3%)
296
(2.5%)
82
(0.7%)
38
(0.3%)
19
(0.2%)
4
(0.0%)
1
(0.0%)
11,819
(13.0%)
Southeast
15,652
(83.8%)
2,246
(12.0%)
588
(3.1%)
93
(0.5%)
58
(0.3%)
44
(0.2%)
1
(0.0%)
0
(0.0%)
18,682
(20.5%)
North-Central
29,172
(95.9%)
654
(2.1%)
366
(1.2%)
100
(0.3%)
73
(0.2%)
53
(0.2%)
12
(0.0%)
2
(0.0%)
30,432
(33.4%)
South-Central
13,262
(89.8%)
1,115
(7.6%)
293
(2.0%)
42
(0.3%)
26
(0.2%)
30
(0.2%)
0
(0.0%)
0
(0.0%)
14,768
(16.2%)
Mountain
6,895
(99.0%)
35
(0.5%)
15
(0.2%)
3
(0.0%)
5
(0.1%)
12
(0.2%)
0
(0.0%)
0
(0.0%)
6,965
(7.7%)
West
7,881
(96.9%)
43
(0.5%)
87
(1.1%)
41
(0.5%)
42
(0.5%)
38
(0.5%)
3
(0.0%)
0
(0.0%)
8,135
(8.9%)
Other
226
(94.6%)
5
(2.1%)
4
(1.7%)
2
(0.8%)
2
(0.8%)
0
(0.0%)
0
(0.0%)
0
(0.0%)
239
(0.3%)
United States
84,076
4,489
1,649
363
244
196
20
3
91,040
a The procedure for estimating animal units was adopted from Lander et al. (1998).
10-14
-------
Table 10-9. Layer and pullet production by State, 1997.a
Layers
Pullets
Older than
20 Weeks to
13 to 20
Under 13
1 Year
1 Year Old
Weeks Old
Weeks Old
State
(thousands)
(thousands)
(thousands)
(thousands)
Alabama
4,292
6,200
2,066
2,500
Arkansas
6,070
8,351
3,486
3,976
California
15,270
11,010
1,000
3,080
Colorado
1,910
1,760
229
543
Connecticut
1,141
2,318
299
550
Delaware
150
250
0
0
Florida
6,216
4,522
1,045
1,133
Georgia
6,680
13,840
3,120
5,080
Hawaii
465
263
55
80
Idaho
546
385
30
223
Illinois
1,534
1,679
174
380
Indiana
10,238
12,076
1,355
3,479
Iowa
11,655
10,130
1,700
2,150
Kansas
505
843
245
256
Kentucky
1,550
1,650
380
820
Louisiana
940
963
165
370
Maine
2,256
2,523
621
1,495
Maryland
1,518
1,644
428
483
Massachusetts
72
473
3
155
Michigan
2,343
2,817
390
630
Minnesota
6,740
5,215
810
1,895
Mississippi
2,487
4,424
1,407
2,049
Missouri
3,490
3,605
675
1,490
Montana
35
240
45
69
Nebraska
6,011
3,979
563
1,573
New Hampshire
53
106
24
29
New Jersey
931
1,023
174
0
New Mexico
636
536
68
162
New York
1,070
2,400
540
470
North Carolina
4,307
7,306
1,920
2,952
North Dakota
125
140
3
40
Ohio
10,863
16,195
3,400
2,644
Oklahoma
1,910
1,700
310
710
Oregon
1,800
1,200
344
241
Pennsylvania
9,000
13,605
1,650
2,550
Rhode Island
10
61
17
1
South Carolina
2,205
2,424
438
446
South Dakota
800
1,370
175
205
Tennessee
316
922
246
442
Texas
5,630
11,545
2,315
2,700
Utah
849
669
198
151
Vermont
8
171
1
4
Virginia
704
2,759
582
428
Washington
2,900
2,221
1,090
805
West Virginia
285
760
322
292
Wisconsin
1,994
1,989
59
958
Wyoming
8
4
2
2
Other statesb
168
132
5
2
US
140.686
170.398
34.174
50.693
" Preliminary. b AK, AZ, and NV combined to avoid disclosure of individual operations
Source: NASS, 1998.
10-19
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10.3 Waste Management Systems
10.3.1 Broilers
Broiler and roaster housing. Houses used to rear broilers and roasters are usually 40 feet wide and 400 to 500 feet
long. The houses are equipped with automatic feeding systems and automatic closed water systems (not a flow-
through system). Ventilation varies from manual (side curtain) to complete fan ventilation controlled by thermostat
and timer. Brooding (period when auxiliary heat is used) is often done in half to a third of the house and released to
the remainder of the house, which has an impact on nutrient level in the litter in the brooding area. Broilers are
usually grown for 42 to 56 days depending on market weight desired. Roasters are usually grown separated by sex
with the females being harvested at 42 days of age and the males given the space in the entire house until they are
sent to market at 75 to 84 days of age.
Wood shavings are initially added to the houses at a depth of approximately 4 inches and top dressed with about 1-
inch of new shaving between flocks. Litter (bedding and manure) is typically cleaned out completely annually,
although there is a trend toward complete clean-out less often. Between flocks, a machine is often used to clean out
any clumps of litter (termed caking out) that may build up around waterers and feeders. When the broiler or roaster
house is completely cleaned out, the feeders, waterers, and brooding equipment are winched to the ceiling and litter
is removed with a front loader or bobcat to a spreader trucks. Spreader trucks are similar to lime-spreading trucks,
with a moving bed that empties onto large, round metal plates that distribute the litter for use as fertilizer nutrients
for pasture and crops. Rate of application is controlled by the rate at which the moving bed empties and the speed of
the truck. In addition to land application, several other uses of litter are common, including feeding the litter to
cattle as a protein source, composting it and using it as a soil amendment, using it as an ingredient for organic
fertilizer, and burning it as fuel.
Broiler breeding and pullet housing. Pullet houses are generally 40 to 45 feet in width and 300 to 500 feet in
length. Most houses are equipped with drinkers (nipple, trough, or bell type) and mechanical feeders (drag chain,
trough, or pan type). Ventilation is mostly power ventilation; during the winter it is used to remove moisture and
obnoxious gases, and during the summer it aids in removing excess heat produced by the birds.
The pullets are reared on a floor that is covered with a bedding source, 1 to 4 inches deep which can be wood
shavings, rice hulls, chopped straw, peanut hulls, or another product depending on geographical availability. The
bedding absorbs moisture and dilutes the manure produced by the birds when it mixes. This litter mixture is either
removed after each flock (20 to 21 weeks) or used for a second flock, but a small amount of litter as cake
(compacted and concentrated manure/litter mix) is removed and the remaining litter is top dressed with an inch or so
of new bedding material. When the house is totally cleaned out, the litter is pushed to the center of the house and a
front loader places it in a litter spreader to be used as a nutrient source for growing crops. Complete cleaning of the
house is one of the procedures needed to practice good biosecurity and minimize of disease transmission.
Breeder houses are generally 40 to 45 feet in width and 300 to 600 feet in length. There will be a few variations to
these dimensions. Most of the breeder houses are two-thirds slats and one-third litter. Occasionally some breeder
organizations may use a totally littered floor. Slats are elevated (18 to 24 inches) panels of wood slats laid across
supports with 1 inch of space between the slats that allows the fecal material to drop to the floor below. The slats
generally cover one-third of each side of the house for the entire length of the house, with the center section free of
equipment.
The center third of the house is covered with 2 to 6 inches of a bedding source before young breeder layers are
placed in the breeder house. Drinkers, mechanical feeders, and nests are placed over the slat section of the house,
which allows most of the manure produced by the birds to fall beneath the slat area, keeping the area accessible to
the birds cleaner. The breeder house is cleaned after the hens have finished the lay cycle. When the house is
cleaned, all of the equipment (including slats) is removed from the house to allow a front-end loader to push all of
the manure to the center litter section of the house. Then the front-end loader places the mixture of manure and litter
into a litter spreader to be used as a nutrient source for growing crops. A thorough cleaning after each flock
(essentially once per year) removes potentially harmful organisms that might be present to prevent them from
infecting the next flock placed in the house. After removal of all organic matter, the house is disinfected.
10-20
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Two decades ago, breeder layers were housed in systems that were 100 percent litter and had no slat area. Only a
few of these systems are still in use, and litter is handled as described under the pullet system. An extremely small
percentage of the breeder hens are housed in cages so that they can be artificially inseminated and so that detailed
egg production records can be kept for purposes of genetic improvement by the primary breeder organizations. The
manure in these facilities is handled similarly to that in a commercial cage layer facility.
10.3.2 Turkeys
Production systems. The production systems for turkey production are very similar to those for broilers with some
minor, but significant, differences. Most turkeys are produced under contract. As with broilers, an integrated
company provides birds, feed, medicines, bird transport, and technical help. The contract producer provides the
production facilities and labor to grow the birds from hatchling to a market-age bird. For this, the contract producer
receives a guaranteed price, which may be adjusted up or down based on the performance of the birds compared to
other flocks produced or processed by the company during the same span of time. With this type of production, the
contract turkey producer avoids much of the risk associated with production and market variation. In contrast to
broiler production, which is about 99.9 percent integrated as just described, there are variations for turkey
production. Some turkeys are raised by independent turkey producers. Even under this type of production, however,
the independent producer may arrange for feed, poults, medical care, and possibly processing, through contracts. In
addition to independent production, some turkeys are produced on farms owned by the integrator company. The
integrator turkey company may also be the company that processes the birds. However, some turkey integrators
provide all services except the processing, which is arranged by the integrator with a processing company.
Housing equipment. Regardless of the contractual arrangement, all turkeys are produced in very similar housing
and systems. Rearing and housing systems for breeder and market turkeys are very similar. Therefore, descriptions
provided here may be construed to be descriptive of both market and breeder turkeys. Housing systems for turkey
production are very similar across the United States and throughout the rest of North America.
The young turkey poults are received from the hatchery on the day of or the day after hatching. The poults are
placed in barns called brooder houses. These barns are usually 40 to 50 feet wide and 300 to 400 feet long. The
barns have dirt or clay floors covered with 3 to 4 inches of pine shavings or similar bedding. Once bedding has been
used or even exposed to birds, it is usually called litter.
In southern climates, the side walls of these barns are 6 to 8 feet high with a 4- to 5-foot-wide opening that is covered
by wire and curtains. These curtains may be opened or closed to provide ventilation. Ventilation can also be
provided by side wall-mounted fans that pull air out of the barn. Inlets or opened curtains provide areas for air to
then move into the barn. This is a negative-pressure air exchange system.
In northern climates the side walls may be solid, with all ventilation provided by side wall fans or movable solid side
walls. The center of the barn may be 10 to 12 feet high. Each brooder house is equipped with gas-powered heaters
or brooders, hence the name brooder house. Beneath each of these brooders, an 18- to 24-inch-high ring made of
cardboard or a similar material is set up with a 12- to 14-foot diameter. This ring will keep the poults, approximately
300 per ring, in proximity to the brooder to make sure the poults are kept at the proper temperature. In addition, feed
and water are provided in temporary flats and jugs.
In 5 to 9 days the rings, flats, and jugs are removed and the poults are trained to use permanent bell waterers and
circular feed pans. Both water and feed systems are automatic or self-filling. Poults are placed in numbers to
provide approximately 1 square foot per bird. Therefore, a brooder house that is 40 by 400 feet contains 16,000
square feet and can house up to 16,000 poults.
The poults are reared in the brooder house until 6 to 8 weeks of age. At that time, the poults are moved to range or
grower barns, which are constructed very similarly to or the same as the brooder houses. In the grower house the
male birds (toms) are provided approximately 1 square foot of space per 10 lb of live market weight per bird.
Female birds (hens) are provided approximately 1 square foot of floor space for every 8 pounds of live market
weight per bird. For example, toms expected to be marketed at 40 pounds live weight are provided 4 square feet per
bird while hens expected to be marketed at 14 to 16 pounds live weight are provided 2 square feet per bird. These
10-21
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traditional systems as described are termed two-aged farms because two ages of birds can be on the farm at one time.
Once the poults are moved to the grower barn, the brooder house is totally cleaned up for a second group of poults.
This clean-up includes removal of all litter used during the brooding phase. This second group of poults occupies
the brooder house while the first group of birds is still in the grower barn.
This two-age farm system has served the turkey industry for more than 20 years. Currently, however, there are
efforts to modify and change this system due to increased morbidity and mortality, which has been difficult to control
in some geographical areas of turkey production. These areas include but are not limited to North Carolina, South
Carolina, Virginia, and Minnesota. These modifications are directed at raising older birds in facilities removed from
the poults. This provides an opportunity to break any disease cycle that might put the birds, especially the younger
birds, at increased risk for disease.
These current modifications include single-age farms, separate contract brooding farms, separate contract grower
farms, and brood-and-move farms. Single-age farms are farms where poults are placed as described above.
However, the poults are kept on the same farm for the entire production cycle. At 6 to 8 weeks of age, the birds are
provided more floor space and properly sized equipment. Once the birds are transported to the processing plant, the
entire facility is prepared for the next group of birds. Under separate brooding and growing contracts, birds are
brooded by one contract producer and then moved to another farm owned by a second contract producer. In this way
the birds are brooded and then reared on separate farms. Under one brood-and-move system, the poults are handled
similarly but the same contract producer owns both the brooder and grower farm. In another brood-and-move
system, the integrator company owns and operates the brooder farm and moves the poults to contract grower farms.
Litter handling systems. For brooder facilities, the litter is removed after every flock of brooded poults. This
practice is necessary to provide the next group of poults with clean bedding for the lowest possible risk of disease
exposure. For grower systems, the litter is removed once per year. In between flocks, caked manure is removed and
the old litter may be top-dressed with a thin layer of new bedding. For single-age farms, the bedding in the brooding
section is moved to the grower section. New bedding is put in the brooder section, and the facilities are prepared for
the next group of poults.
Litter is usually removed by skid-steer tractors or tractors equipped with front-end loaders or scoops. The litter is
dumped into trucks with lift beds or spreader trucks and transported to holding facilities or end users such as farmers
who will use the litter on crop or pasture land.
10.3.3 Layers
High-rise cage systems. High-rise cage housing is a two-story poultry house with cages for the laying hens in the
top story suspended over the bottom story, where the manure is deposited and stored. The house structure itself is
usually 40 to 60 feet wide and from 400 to 500 feet long. The ventilation system is designed so that the external air
is brought into the top story, brought through the cages where the birds are located, and then over the manure in the
bottom story, and exits through fans in the bottom story side wall. The watering system is a closed (noncontinuous
flow) nipple or cup system.
The ventilation system is designed to dry manure as it is stored. With proper management of waterers preventing
water leaking onto the stored litter, litter moisture is commonly 30 to 50 percent. Litter of 30 percent to 50 percent
can be stored for extended periods of time and handled and land applied similar to a litter product of broilers or
turkeys. Usually clean-out of the high-rise is timed to coincide with availability of crop land for application or flock
movement.
Scrape-out and belt systems. Housing facilities for scrape-out and belt manure removal cage systems are the same
dimensions as high-rise units except they have one story. Watering systems in these operations are also closed, using
nipple or cup waterers. Ventilation varies from fan-controlled to adjustable curtains in the side wall.
Cages in the scrape-out system are suspended over a shallow pit, which is scraped out to the end of the house with a
small tractor or a pit scraper. Another scraping system in use includes a wench and cable to supply the power to
10-22
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move the scraper from one end of the house to the other, scraping the manure in front of it to an unloading device at
the end of the house, which places the manure in a field spreader.
Belt systems have a continuous belt under the different tiers of cages that moves the manure to the end of the house,
where it is placed into a field spreader or some other suitable storage device. Some of the newer belt systems
attempt to move air over the manure on the belt in an attempt to dry the manure before its removal.
The manure from scrape-out and belt systems usually has a moisture content of between 70 and 85 percent.
Therefore, the manure must be handled as a slurry and is either injected or land applied with a spreader that can
handle the high-moisture manure.
Flush cage housing. Housing, equipment, and ventilation are similar to the scrape-out system except with regard to
how the manure is handled. Cages are suspended over a shallow pit as in the scrape-out system, but water is used to
move the manure from under the cages to the end of the house, where the water and manure mixture is placed in an
anaerobic lagoon. The water used to flush the manure pits is recycled from the lagoon. A variation of this system
consists of solids separation by means of a primary lagoon and a secondary lagoon. Lagoon levels are maintained so
that sufficient storage is provided for the 25-year, 24-hour storm by irrigating liquid onto pasture or cropland. Some
states require storage of more than the 25-year, 24-hour storm. North Carolina, for example, requires storage for the
equivalent of two such storms.
Other systems. A few litter and slat/litter houses are used to produce table eggs. These same housing systems are
used for the breeders that produce fertile eggs for production of hatching eggs, which will produce the commercial
layer chicks that will eventually produce table eggs.
10.4 Economic Considerations
The predominant manure management system in all regions of the country involves the removal of poultry litter
(wood shavings and manure) from production houses after one or more broods have been reared on the same litter.
Equipment costs for a typical broiler operation are displayed here:
Item
Litter cruster machine (for removing cake between flocks)
Tractor to pull cruster machine
Front-end loader tractor (bobcat type)
Spin spreader and truck
Litter storage shed (40-ft by 160-ft to store annual production
from four 40-ft by 500-ft production houses)
Total Investment $91,000.00 or $0.875/bird capacity based
on a four-house family operation
Turkey operations follow the same basic manure management strategy as broiler operations with certain variations.
Costs equate to $106,000 or $2.20 per bird, following the same criteria as above.
Costs for production houses and equipment (including fans and waterers) vary widely among regions. The 1997 cost
of housing and equipment was more than $5 and $4.45 per square foot of building for broilers and turkeys,
respectively, in North Carolina.
Maintaining good litter conditions inside the house results in a litter product containing optimum moisture and
nutrient contents for land application. This nutrient resource has excellent physicochemical characteristics that can
greatly improve the quality of cultivated soils. In addition to nutrients, poultry manure provides organic matter that
Costs
$9,500.00
$12,500.00
$15,000.00
$32,000.00
$22,000.00
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enhances soil water-holding capacity, improves soil aeration, and increases retention of certain nutrients (Reeves et
al., 1998, cited in NCSU, 1998). Some of the costs of poultry manure management will thus be defrayed by savings
in fertilizer expenditures and invaluable soil properties that will enhance crop growth.
The high nutrient content of poultry manure presents alternative management strategies. Composting and bagging a
pelleted poultry manure fertilizer produces a marketable product for the commercial horticulture industry. Ease of
handling, lack of objectionable odor, and freedom from pathogens makes poultry manure an attractive soil
amendment (Trumbauretal., 1994, cited in NCSU, 1998).
The high concentration of phosphorus and protein in poultry manure has been capitalized upon as a dietary
supplement for cattle in poultry-producing areas since the 1950s. Reeves et al. (1998, cited in NCSU, 1998) report
that 20 to 25 percent of litter consists of crude proteins after five to six flocks. This translates into an $80 to $120
value per ton when formulated into a cattle feed (NSOE, 1996, cited in NCSU, 1998).
10.5 Bibliography
Lander, C.H., D. Moffitt, and K. Alt. 1998. Nutrients Available from Livestock Manure Relative to Crop Growth
Requirements. U.S. Department of Agriculture, Natural Resources Conservation Service, Resource
Assessment and Strategic Planning Working Paper 98-1. . Accessed October 15, 1998.
NASS. 1998. Agricultural Statistics 1998. . File 98_ch8.pdf
accessed October 19, 1998.
NCSU. 1998. Draft of Swine and Poultry Industry Characterization, Waste Management Practices andModel
Detailed Analysis of Predominantly Used Systems. North Carolina State University, Raleigh, North
Carolina. September.
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11.0 Treatment Technology Efficiency Summary
11.1 Introduction
This chapter summarizes technologies and practices used to collect, store, treat, and dispose of manure with an
emphasis on treatment efficiency and available information on cost. In earlier chapters it was demonstrated that the
major manure disposal method for most operations is application on their own land. As animal feeding operations
continue to consolidate (i.e., more large operations) to take advantage of specialized labor and equipment, applying
manure on their own land at rates that balance crop uptake with existing soil nutrients will become more difficult.
To encourage agronomic application of manure, some states have developed "manure banks" to help animal feeding
operators find off-farm land for manure application. Some operators have built manure sheds to improve the ability
to apply manure during more desirable times of the year. Because of the focus on nutrient management, most of the
published treatment efficiency data is related to solids and nutrient removal or concentrations of major nutrients.
Thus, the majority of the information presented in this chapter is related to solids and nutrients.
Several sources of literature provide national data summaries or typical values for a variety of common animal types
and technologies. These data could be used to serve as a baseline for existing systems. In recent years, research has
focused on odor control and improved nutrition strategies. Odor control research is largely driven by the need to
maintain animal health and avoid nuisance odor liability. As odor controls are implemented there is likely to be a
decrease in ammonia volatilization, the primary mechanism through which nitrogen is lost from stored manure.
From an environmental perspective, this industry change might be advantageous since some research has shown that
ammonia volatilization might contribute to atmospheric deposition in nearby watersheds (e.g., Paerl et al., 1995 and
Fisher and Oppenheimer, 1991). Waste minimization technologies such as improved nutrition strategies (e.g., split-
sex feeding, phytase addition) also show promise for reducing the production and nutrient content of manure. While
split-sex feeding has been adopted by some operators, feed additives (e.g., phytase) have been cost neutral, in some
instances. Anaerobic digestion and composting, both well-understood and value-added technologies, have
reemerged due to programs such as EPA's AgStar Program for anaerobic digestion. However, Day and Funk (1998)
state that there is still a need for continued research and demonstration of low-maintenance and less capital-intensive
anaerobic digestion and development of compost systems that can receive and compost large volumes of high-
moisture manure in a labor-efficient manner.
At the end of this chapter is an extensive bibliography of standard references and recent papers from proceedings,
conferences, and journals that were considered for this chapter. Results from selected publications that included
treatment efficiency or cost information are presented to supplement standard reference material. In most cases,
information on novel and emerging technologies is based on a few studies, and further research is likely needed
before these practices can be reliably implemented on a general basis. While it is reasonable to suspect that a
technology proven effective for one animal type and location could be considered for a similar situation, it would be
premature to assume that the technology could be transferred to other animal types and locations. Finally, exclusion
or inclusion from this document does not imply disapproval or endorsement.
11.2 Waste Generation
The Midwest Planning Service, the American Society of Agricultural Engineers, and the USD A provide quantities
and characteristics of manure excreted for a variety of animal types (Tables 11-1 through 11-3). Tables 11-4 through
11-6 provide general characteristics associated with milking center waste, poultry waste litter, and a comparison of
animal waste with and without bedding, respectively. In states like Texas, feedlot operators estimate manure and
constituent characteristics based on the mean plus one standard deviation (from Table 11-3) in order to obtain a
permit (Sweeten, 1998). While excretion data exists for chemical parameters other than the major nutrients,
relatively little has been published about the effect of different handling, storage, and treatment practices on chemical
parameters other than nitrogen, phosphorus, and potassium. For example, hog manure includes copper and zinc,
while broiler manure contains copper, zinc, and arsenic. Some concern has also been raised about organic
compounds in manure such antibiotics, pesticides, and hormones, and their associated
11-1
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Table 11-1. Annual volume and nutrient content of raw manure.
Animal Category
Manure
Produced
Nutrients Prodi
(lb nutrient/1000
iced
*al/yr)
1000 gal/yr.
N
P
K
Farrow, per sow and litter
0.989
36.9
9.7
16.8
Nursery, per pig cap.
0.101
57.7
15.8
30.0
Grow-fin, per pig cap.
0.440
58.1
19.2
39.9
Breed-gestation, per sow cap.
0.396
59.9
24.2
36.8
Dairy cow, per mature cow
5.057
41.1
8.6
27.6
Dairy heifer, per hd cap.
2.639
42.2
9.1
28.4
Dairy calf, per hd cap.
0.528
41.5
9.1
28.7
Veal calf, per hd cap.
0.352
36.3
13.6
43.1
Beef cows, per hd cap.
2.770
47.4
12.7
34.2
Feeder calf (500#), per hd cap.
1.275
48.7
13.0
30.0
Fattening cattle, per hd cap.
2.551
48.7
13.0
30.0
Broilers, per bird cap.
0.006
130.4
36.3
44.3
Pullets, per bird cap.
0.007
116.2
31.4
45.9
Layers, per bird cap.
0.011
110.2
35.4
37.7
Tom-turkeys, per bird cap.
0.025
116.5
50.9
36.3
Hen-turkevs, per bird cap.
0.025
103.8
46.6
32.0
Ducks, per bird/vr.
0.014
80.3
42.1
24.5
Source: MWPS, 1993 as presented by Jones and Sutton, 1994.
by-products. For example, nonylphenol residue concentrations are similar to those found in municipal biosolids
(Chaney, 1997). Although a comprehensive scan of pollutant parameters has not been performed, the leading issues
related to ground and surface waters appear to be nitrogen and phosphorus.
Site-specific manure nutrient content is affected by numerous factors including rations, feed waste, water waste,
nutrient loss, and bedding. The value of manure nutrients is dependent on the nutrient status of the field to which it
is applied, the nutrient needs of the crop to be grown, the nutrient content of the manure, and the cost of purchased
nutrients. The value of manure as a nutrient source is greatest when applied to a soil of low fertility. When applying
manure at a rate to satisfy the N needs of a crop, P and K are usually applied in excess, and excess nutrients would
not be given any value. In addition, continued build-up of soil P might be undesirable since it has resulted in some
instances of increased dissolved P losses from fields (Sharpley, 1995). At the same time, manure has other benefits
such as providing micronutrients and organic matter. Table 11-7 presents the average annual value (1994 dollars) of
manure based on the nitrogen ($0.20/lb), phosphorus ($0.28/lb), and potassium ($0.16/lb) content for a variety of
operations in Minnesota. Note, that in a 1995 study of dairy operations in the Chesapeake Bay, Ritter and
Scarborough (1995) used nitrogen, phosphorus, and potassium costs of $0.22, $0.25, and $0,132 per pound.
In a more recent study, Lorimor and Xin (1998) evaluated poultry manure volume and nutrient production of layers
from high-rise houses containing 80,400 to 124,500 birds at four commercial facilities in Iowa. Measured manure
production was 10.5 tons/1000 birds/year with an average moisture content of 41 percent. Nutrient production was
shown to be 385, 379, and 457 lb/1000 birds/year of N, P, and K, respectively. Different manure handling systems
had a different effect on manure moisture content—manure had a higher moisture content when the manure dropped
directly into storage rather than be allowed to remain on boards beneath the cages for a period of time before
removal to a storage pile.
11-2
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Table 11-2. Livestock waste characterization as excreted manure.0
Moistur
Weight
Volume
e
TS
TS
vs
FS
COD
bods
N
P
K
C:N
Animal Category
lb/d/1000#
ft3/d/1000#
%
% w.b.
lb/d/1000#
lb/d/1000#
lb/d/1000#
lb/d/1000#
lb/d/1000#
lb/d/1000#
lb/d/1000#
lb/d/1000#
ratio
Dairy3
Cow, Lactating
80.00
1.30
87.50
12.50
10.00
8.50
1.50
8.90
1.60
0.45
0.07
0.26
10
Cow, Dry
82.00
1.30
88.40
11.60
9.50
8.10
1.40
8.50
1.20
0.36
0.05
0.23
13
Heifer
85.00
1.30
89.30
10.70
9.14
7.77
1.37
8.30
1.30
0.31
0.04
0.24
14
Beef
Feeder
High forage diet
59.10
0.95
88.40
11.60
6.78
6.04
0.74
6.11
1.36
0.31
0.11
0.24
11
High energy diet
51.20
0.82
88.40
11.60
5.91
5.44
0.47
5.61
1.36
0.30
0.094
0.21
10
450 - 750 lb
58.20
0.93
87.00
13.00
7.54
6.41
1.13
6.00
1.30
0.30
0.10
0.20
12
Cow
63.00
1.00
88.40
11.60
7.30
6.20
1.10
6.00
1.20
0.33
0.12
0.26
10
Swineb
Grower (40-220 lb)
63.40
1.00
90.00
10.00
6.34
5.40
0.94
6.06
2.08
0.42
0.16
0.22
7
Replacement gilt
32.80
0.53
90.00
10.00
3.28
2.92
0.36
3.12
1.08
0.24
0.08
0.13
7
Sow, gestation
27.20
0.44
90.80
9.20
2.50
2.13
0.37
2.37
0.83
0.19
0.063
0.123
6
Sow, lactation
60.00
0.96
90.00
10.00
6.00
5.40
0.60
5.73
2.00
0.47
0.15
0.30
6
Boar
20.50
0.33
90.70
9.30
1.90
1.70
0.30
1.37
0.65
0.15
0.05
0.10
6
Nursing/nursery pig
106.00
1.70
90.00
10.00
10.60
8.80
1.80
9.80
3.40
0.60
0.25
0.35
8
(0 - 40 lb)
Poultry3
Layer
60.50
0.93
75.00
25.00
15.10
10.80
4.30
13.70
3.70
0.83
0.31
0.34
7
Pullet
45.60
0.73
75.00
25.00
11.40
9.70
1.70
12.20
3.30
0.62
0.24
0.26
9
Broiler
80.00
1.26
75.00
25.00
20.00
15.00
5.00
19.00
5.10
1.10
0.34
0.46
8
Turkey
43.60
0.69
75.00
25.00
10.90
9.70
1.25
12.30
3.30
0.74
0.28
0.28
7
Duck
-
-
-
-
12.00
7.00
5.00
9.50
2.50
0.70
0.30
0.50
6
Other livestock3
Veal
60.00
0.96
97.50
2.50
1.50
0.85
0.65
1.50
0.37
0.20
0.03
0.25
2
Sheep
40.00
0.63
75.00
25.00
10.00
8.30
1.76
11.00
1.00
0.45
0.07
0.30
10
Horse
50.00
0.80
78.00
22.00
11.00
9.35
1.65
-
-
0.28
0.05
0.19
19
a Increase solids and nutrients by 4% for each 1% feed waste more than 5%.
b Average daily production for weight range noted. Increase solids and nutrients by 4% for each 1% feed waste more than 5%.
c 1000# refers to 1,000 lb of animal live weight.
Source: USDA, 1992.
-------
Table 11-3. Fresh manure production and characteristics per 1,000 lb live animal
mass per day. Values in table are parameter mean (standard deviation).
Parameter
Animal Type
Dairy
Beef
Veal
Swine
Sheep
Goat
Horse
Layer
Broiler
Turkey
Duck
Total manure, lb
86
(17)
58
(17)
62
(24)
84
(24)
40
(11)
41
(8.6)
51
(7.2)
64
(19)
85
(13)
47
(13)
110
Urine, lb
26
(4.3)
18
(4.2)
39
(4.8)
15
(3.6)
10
(0.74)
Density, lb/ft3
62
(4)
63
(4-7)
62
62
(1.5)
64
(4)
63
63
(5.8)
60
(2-4)
63
63
Total solids, lb
12
(2.7)
8.5
(2.6)
5.2
(2.1)
11
(6.3)
11
(3.5)
13
(1)
15
(4-4)
16
(4-3)
22
(1.4)
12
(3.4)
31
(15)
Volatile solids, lb
10
(0.79)
7.2
(0.57)
2.3
8.5
(0.66)
9.2
(0.31)
10
(3.7)
12
(0.84)
17
(1.2)
9.1
(1.3)
19
BOD5, lb
1.6
(0.48)
1.6
(0.75)
1.7
3.1
(0.72)
1.2
(0.47)
1.7
(0.23)
3.3
(0.91)
2.1
(0.46)
4.5
COD, lb
11
(2.4)
7.8
(2.7)
5.3
8.4
(5-3)
11
(2-5)
11
(2-7)
16
(18)
9.3
(1.2)
27
PH
7
(0.45)
7
(0-34)
8.1
7.5
(0-57)
7.2
6.9
(0-56)
Total Kjeldahl
nitrogen, lb
0.45
(0.096)
0.34
(0.073)
0.27
(0.045)
0.52
(0-21)
0.42
(o.ii)
0.45
(0-12)
0.3
(0.063)
0.84
(0.22)
1.1
(0.24)
0.62
(0-13)
1.5
(0-54)
Ammonia nitrogen,
lb
0.079
(0.083)
0.086
(0.052)
0.12
(0.016)
0.29
(o.i)
0.21
(0.18)
0.08
(0.018)
Total phosphorus,
lb
0.094
(0.024)
0.092
(0.027)
0.066
(0.011)
0.18
(o.i)
0.087
(0.03)
0.11
(0.016)
0.071
(0.026)
0.3
(0.081)
0.3
(0.053)
0.23
(0.093)
0.54
(0-21)
Orthophsphorus, lb
0.061
(0.058)
0.03
0.12
0.032
(0.014)
0.019
(0.0071)
0.092
(0.016)
0.25
Potassium, lb
0.29
(0.094)
0.21
(0.061)
0.28
(0.1)
0.29
(0.16)
0.32
(0.11)
0.31
(0.14)
0.25
(0.091)
0.3
(0.072)
0.4
(0.064)
0.24
(0.08)
0.71
(0.34)
Calcium, lb
0.16
(0.059)
0.14
(0.11)
0.059
(0.049)
0.33
(0.18)
0.28
(0.15)
0.29
(0.11)
1.3
(0.57)
0.41
0.63
(0.34)
Magnesium, lb
0.071
(0.016)
0.049
(0.015)
0.033
(0.023)
0.07
(0.035)
0.072
(0.047)
0.057
(0.016)
0.14
(0.042)
0.15
0.073
(0.0071)
Sulfur, lb
0.051
(0.01)
0.045
(0.0052)
0.076
(0.04)
0.055
(0.043)
0.044
(0.022)
0.14
(0.066)
0.085
Sodium, lb
0.052
(0.026)
0.03
(0.023)
0.086
(0.063)
0.067
(0.052)
0.078
(0.027)
0.036
0.1
(0.051)
0.15
0.066
(0.012)
Chloride, lb
0.13
(0.039)
0.26
(0.052)
0.089
0.56
(0.44)
Iron, lb
0.012
(0.0066)
0.0078
(0.0059)
0.00033
0.016
(0.0097)
0.0081
(0.0032)
0.016
(0.0081)
0.06
(0.049)
0.075
(0.028)
Manganese, lb
0.0019
(0.00075)
0.0012
(0.00051)
0.0019
(0.00074)
0.0014
(0.0015)
0.0028
(0.0021)
0.0061
(0.0022)
0.0024
(0.00033)
Boron, lb
0.00071
(0.00035)
0.00088
(0.000064)
0.0031
(0.00095)
0.00061
(0.0003)
0.0012
(0.00048)
0.0018
(0.0017)
Molybdenum, lb
0.000074
(0.000012)
0.000042
0.000028
(0.00003)
0.00025
(0.00038)
0.000083
(0.000033)
0.0003
(0.000057)
Zinc, lb
0.0018
(0.00065)
0.0011
(0.00043)
0.013
0.005
(0.0025)
0.0016
(0.001)
0.0022
(0.0021)
0.019
(0.033)
0.0036
0.015
(0.012)
Copper, lb
0.00045
(0.00014)
0.00031
(0.00012)
0.000048
0.0012
(0.00084)
0.00022
(0.000066)
0.00053
(0.00039)
0.00083
(0.00084)
0.00098
0.00071
(0.0001)
Cadmium, lb
0.000003
0.000027
(0.000028)
0.0000072
0.0000051
0.000038
(0.000032)
Nickel, lb
0.00028
0.00062
0.00025
Lead, lb
0.000084
(0.000012)
0.000084
0.00074
All values in table are wet basis. All nutrients and metals values are given in elemental form. Typical live animal masses for which manure values
represent are dairy, 1,400 lb; beef, 800 lb; veal, 200 lb; swine, 135 lb; sheep, 60 lb; goat, 140 lb; horse, 1000 lb; layer, 4 lb; broiler, 2 lb; turkey, 15
lb; and duck, 3 lb. Parameter means within each animal species are comprised of varying populations of data. Maximum numbers of data points
for each species are dairy, 85; beef, 50; veal, 5; swine, 58; sheep, 39; goat, 3; horse, 31; layer, 74; broiler, 14; turkey, 18; and duck, 6.
Source: ASAE, 1998, ASAE Standard D384.1 DEC93.
11-4
-------
Table 11-4. Dairy waste characterization of milking center.
Components
Units
Milking center
Milk house
Milk house and
milking parlor
Milk house,
milking parlor
and holding area3
Milk house,
milking parlor
and holding areab
Volume
ft3/d/1000#
0.22
0.60
1.40
1.60
Moisture
%
99.72
99.40
99.70
98.50
TS
% w.b.
0.28
0.60
0.30
1.50
VS
lb/1000 gal
12.90
35.00
18.30
99.96
FS
lb/1000 gal
10.60
15.00
6.70
24.99
COD
lb/1000 gal
25.30
41.70
B0D5
lb/1000 gal
8.37
N
lb/1000 gal
0.72
1.67
1.00
7.50
P
lb/1000 gal
0.58
0.83
0.23
0.83
K
lb/1000 gal
1.50
2.50
0.57
3.33
C:N ratio
10
12
10
7
" Holding area scraped and flushed - manure excluded. b Holding area scraped and flushed - manure included.
Source: USDA, 1992.
Table 11-5. Characterization of poultry waste litter.
Component
Units
Layer
high-rise3
Broiler
Broiler
breederb
Turkey
Duck"
Weight
lb/d/1000#
24.00
35.00
24.30
Moisture
%
50.00
24.00
34.00
34.00
11.20
TS
% w.b.
50.00
76.00
66.00
66.00
88.80
lb/d/1000#
12.00
26.50
16.10
VS
lb/d/1000#
21.40
58.60
FS
lb/d/1000#
5.10
30.20
N
lb/d/1000#
0.425
0.68
1.06
0.88
2.31
NH4-N
lb/d/1000#
0.01
P
lb/d/1000#
0.275
0.34
1.32
0.40
K
lb/d/1000#
0.30
0.40
1.19
0.45
C:N ratio
9
14
a No bedding or litter added to waste.
b All values are precent wet basis.
Source: USDA, 1992.
11-5
-------
Table 11-6. Approximate fertilizer nutrient values of animal manure as
Nutrient Content (lb/ton)
Type of System
Total N
NH,
p,o<
K,0
Swine
No Bedding
10
6
9
8
Bedding
8
5
7
7
Beef Cattle
No Bedding
21
7
14
23
Bedding
21
8
18
26
Dairy
No Bedding
9
4
4
10
Cattle
Bedding
9
5
4
10
Poultry
Without Litter
33
26
48
34
With litter
56
36
45
34
Deep pit (compost)
68
44
64
45
Table 11-7. Approximate value (1994 dollars) of nutrients in animal manure as produced
from a solid manure handling system in Minnesota.
Approx.
N
p2o5
k2o
Type of operation
Value
(lb/ton)
(lb/ton)
(lbs/ton)
60 head dairy at 1,300 lb
Without Bedding
$8,370
9
4
10
with replacements, 50%
increase from replacements
With Bedding
$10,245
100 head Beef at 1,000 lb
Without Bedding
$6,730
21
14
23
With Bedding
$8,076
21
18
26
200 head finishing pigs at
Without Bedding
$3,561
10
9
8
2001b
With Bedding
$3,820
8
7
7
27,500 layers at 4 lb
Without Litter
$16,060
27
20
17
With Litter
$17,666
20
16
13
20 percent increase in manure produced because of bedding, N=$0.20/lb, P=$0.28/lb, K=$0.16/lb
Source: Reichow, 1995.
11.3 Waste Reduction Through Feeding Practices
Wasted feed can increase the waste generated. For example, for each 1 percent of feed wasted above 5 percent, the
solid and nutrient values presented in Table 11-2 are increased by 4 percent. To reduce waste some swine growers
have switched to pelletized feed. The design of feeders and waterers are being improved to reduce waste and
overflow. For example, some poultry houses have alarms that indicate when there is a water line break.
Numerous advances have also been made to improve feeding efficiency, thereby reducing waste. Knowledge about
animal nutrition requirements and feed composition has allowed operators to customize feeding to animal type and
performance. For example, some swine operations have already implemented multi-phase and/or split-sex feeding.
Swine and poultry are better able to digest feed if it is more finely ground. Other studies have shown that typical
copper supplements in poultry feed exceed requirements, resulting in enlargement of the proventriculus in broilers
(Wideman, 1996). At the University of Kentucky, reductions in dietary zinc and copper in nursery pigs had no
impact on pig performance (Cromwell, 1998). At Purdue University, sulfurous volatile organic carbons have been
reduced 63 percent by controlling dietary protein intake (Sutton, in progress). Amino acid additions to pig feed such
as lysine allow a reduction in the total protein intake, which results in lower excretion of total nitrogen and up to 45
percent less ammonia (Sutton, in progress). Section 9.3.1 provides more details about dietary manipulation to reduce
nutrient excretion from swine operations. Section 9.3.1 also provides a preliminary cost analysis of some
alternatives that demonstrate dietary manipulation to be cost neutral in some situations (NCSU, 1998). Boland et al.
(1997) found that phytase adoption is likely to have little economic impact for swine producers under current
conditions. Some anecdotal evidence also suggests that phosphorus loading from beef and dairy cattle waste can be
11-6
-------
reduced by changing the form and type of feed, although published results were not found during this literature review.
Digestability and degradability of typical feeds have also been extensively examined. Broilers, for instance, absorb
about 20 to 30 percent of the phosphorus in the corn and soybeans they ingest. Food additives such as phytase allow
animals to assimilate more phosphorus resulting in decreased phosphorus in manure. The inter-relationships
between phosphorus, phytase, calcium, Vitamins D and E, and magnesium are now better understood. Additives for
rumen and hindgut micrflora may alter digestability and in some cases reduce volatility and odor. A genetically
engineered corn contains a phosphorus compound that is more readily assimilated, resulting in half the normal
amount of phosphorus excreted by poultry (Farm Journal, 1998) and two-thirds the normal amount in pigs (Spencer,
1998). Subsequent land application of broiler litter on tall fescue plots resulted in 22 percent less phosphorus runoff
as compared to unaltered corn. Phosphorus runoff decreased by 26 percent when genetically engineered corn and
phytase were used (Moore, 1995). Manure with less phosphorus will tend to have a nitrogen-to-phosphorus ratio
more in line with crop nutrient requirements. In addition, some plants naturally contain or have been modified to
produce antibiotic compounds, reducing the need to directly add these substances to animal feed.
11.4 Comparison of Common Waste Collection, Storage, and Treatment Practices
A variety of technologies are used for waste collection including
< Scrapers and front-end loaders for paved outside feeding areas and freestalls and unpaved beef feedlots and a
growing number of dairies in arid regions.
< Front-end loaders and other specialized equipment for bedded or litter systems common in dairy loafing sheds,
turkeys for slaughter, pullets, broilers, and hoop structures for swine.
< Control structures for runoff.
< Flush systems for dairies, swine, and layers.
< Under-house collection common to swine and layers.
The selection of animal production and housing techniques determines whether the waste will be managed as a
liquid, semisolid, or solid (see Figure 11-1) and ultimately determines the selection of storage, treatment, and
disposal technologies used. Other factors that effect selection include location, capital versus labor cost, automation,
operator preference, dust and odor control, and, as demonstrated in a number of surveys, ground and surface water
protection. The type of manure and how it is collected has a direct impact on the nutrient value of the waste and its
value as a soil amendment or for other uses.
PERCENT TOTAL SOLIDS
0 5 10 15 20 25 30
LIQUID
SEMISOLID
SOLID
WATER ADDE
D
BEDDING ADDED
PUMPABLE
SCRAPER AND B
JCKETLOAD
LIQUID MANURE
| STACKABLE
SOLID MANURE
HANDLING SYSTEMS
HANDLING SYSTEMS
Figure 11-1. Manure characteristics that influence management
options (after Ohio State University Extension, 1998).
11-7
-------
Solid manure storage can range from simply-constructed mounds inside feedlots to manure sheds that are designed to
prevent runoff and leaching. In liquid manure handling systems, the manure is typically stored under house, in
aboveground or belowground steel or concrete tanks, or in lagoons. In addition to storage, lagoons also provide
treatment. Most lagoons operate anaerobically (although a lagoon receiving only milking parlor waste will usually
operate aerobically). Aerated lagoons have received less attention due to increased costs; however, decreased odor
might increase their use. Svoboda (1995) achieved nitrogen removal from 47 to 70 percent depending on aeration
through nitrification and denitrification in a 24 m3 aerobic treatment reactor using whole pig slurry in Scotland.
Secondary, or biological, treatment (such as oxidation ditches, activated sludge, and rotating biological contactors)
can be used to treat manure in the same way as it is used to treat human wastes. However, it is an expensive
technology in comparison to what is currently in use, and does not eliminate the resulting liquid effluent and solid
sludge.
Lagoons may be either lined (clay or synthetic material) or unlined, depending on factors considered prior to
construction. Some lagoons were designed assuming they would "self-seal." Other lagoons have leaked due to
disturbing the bottom liner during lagoon pumpout. Lagoon sidewalls have also cracked after repeated drying and
wetting cycles that occur following lagoon emptying. Some farmers have reported worm holes in the sidewalls of a
lagoon that contribute to leaching. In an evaluation of an earthen-lined dairy manure storage basin in Wisconsin,
physicochemical and biological mechanisms were responsible for creating macropores resulting in preferential flow
and leakage (McCurdy, 1993).
The effect of some lagoons on ground water has been fairly well documented. For example, in a targeted survey of
34 lagoons built on swine operations before the 1993 North Carolina requirement to meet NRCS standards, 13
lagoons were shown to have seepage losses such that ground water samples 125 ft from the lagoon had strong to very
strong levels of N03-N. Another 9 lagoons had ground water samples that exceeded the NO 3-N drinking water
standard, but were expected to dissipate quickly with increasing distances from the lagoon. Surface water samples
indicated that 1 of 16 lagoons was the likely cause of nearby surface water nutrient enrichment, while 8 of 16
lagoons are potentially contributing to nearby surface water nutrient enrichment (Huffman and Revels, 1998). At a
clay-lined swine waste lagoon located on the Delmarva Peninsula, ammonium nitrogen was above 1,000 mg/1 N at
shallow wells around the lagoon; chlorides and TDS were also high (Ritter, 1990). Some research has been done to
evaluate the application of surfactants for enhancing soil liner materials in animal waste storage and treatment
lagoons. In a laboratory experiment on sandy loam soil, optimum surfactants were found to reduce saturated
hydraulic conductivity and did not negatively impact mechanical compaction characteristics; however, no influence
on nitrate mobility was observed (Allred and Brandvold, 1998).
The proportion of phosphorus and potassium remaining in manure after storage is generally higher than nitrogen
except when considering open lots or lagoons. Runoff and leaching from open lots can range from 20 to 40 percent
of the phosphorus and 30 to 50 percent of the potassium. If runoff control systems such as settling basins and
holding ponds are employed, much of the phosphorus and potassium can be recovered. It is also possible for up to
80 percent of the phosphorus in lagoons to accumulate in bottom sludges (MWPS, 1993). Table 11-8 is a
comparison of livestock waste characteristics in anaerobic, aerobic, and runoff ponds, and Table 11-9 presents the
percent of original nutrient content of manure retained by various management systems (USDA, 1992). Sweeten
(1998) also provides a summary of beef feedlot runoff characteristics.
Jones and Sutton (1994) analyzed manure nutrient content just before land application. Table 11-10 shows the
nutrient concentrations obtained from liquid manure pit samples. These concentrations were compared to those
presented in Table 11-1 to determine the change in nutrient value. For example, nitrogen as excreted from a nursery-
sized pig can be estimated as 0.101 x 57.7 = 5.83 lb-N/year. From Table 11-10, the nitrogen after storage would be
0.130 x 25.00 = 3.25 lb-N/year or a 44 percent decrease. On amass basis for pit storage, nitrogen decreases range
from 11 to 47 percent; phosphorus, 9 to 67 percent; and potassium, 5 to 42 percent. Comparable values from Table
11-9 (i.e., manure stored in pits beneath slatted floors) indicate that nitrogen decreases range from 10 to 30 percent,
and phosphorus and potassium decreases range from 5 to 15 percent. Table 11-11 shows the nutrient concentrations
obtained from anaerobic lagoon samples. These concentrations were compared to those presented in Table 11-1 to
determine the change in nutrient value. On a mass basis for a lagoon, nitrogen decreases range from 76 to 84
percent; phosphorus, 78 to 92 percent; and potassium, 71 to 85 percent. Comparable values from Table 11-9 (i.e.,
manure treated in anaerobic lagoon) indicate that nitrogen
11-8
-------
Table 11-8. Livestock waste characterization in anaerobic, aerobic, and runoff ponds.
Component
Units
Anaerobic Lagoon
Aerobic
Lagoon
Feedlot Runoff Pond
Supernatant
Sludge
Supernatant
Supernatant
Sludge
Dairy
Swine
Poultry
Dairy
Swine
Poultry
Dairy
Beef
Layer
Pullet
Layer
Pullet
Moisture
%
99.75
99.75
99.50
99.70
90.00
92.40
86.90
92.60
99.95
99.70
82.80
TS
% w.b.
0.25
0.25
0.50
0.30
10.00
7.60
13.10
7.40
0.05
0.30
17.20
VS
lb/1000 gal
9.16
10.00
18.33
10.83
383.18
379.89
404.06
314.09
1.67
7.50
644.83
FS
lb/1000 gal
11.66
10.83
23.32
14.17
449.82
253.27
687.32
302.42
2.50
17.50
788.12
COD
lb/1000 gal
12.50
10.00
433.16
538.18
1.25
11.67
644.83
bod5
lb/1000 gal
2.92
3.33
0.29
N
lb/1000 gal
1.67
2.91
6.25
3.00
20.83
25.00
32.50
24.17
0.17
1.67
51.66
nh4-n
lb/1000 gal
1.00
1.83
4.58
2.24
4.17
6.33
7.66
4.91
0.10
1.50
P
lb/1000 gal
0.48
0.63
0.83
0.75
9.16
22.50
45.82
27.49
0.08
17.50
K
lb/1000 gal
4.17
3.16
8.33
7.00
12.50
63.31
6.00
6.17
7.50
14.17
C:N ratio
3
2
2
2
10
8
7
7
Source: USDA, 1992.
-------
Table 11-9. Percent of original nutrient content of manure retained by various management systems.
Management System
Beef
Dairy
Poultr
V
Swine
N
P
K
N
P
K
N
P
K
N
P
K
Manure stored in open lot, cool humid region
55-70
70-80
55-70
70-85
85-95
85-95
55-70
65-80
55-70
Manure stored in open lot, hot, arid region
40-60
70-80
55-70
55-70
85-95
85-95
Manure liquids and solids stored in a covered,
essentially watertight structure
70-85
85-95
85-95
70-85
85-95
85-95
75-85
85-95
85-95
Manure liquids and solids stored in an uncovered,
essentially watertight structure
60-75
80-90
80-90
65-75
80-90
80-90
70-75
80-90
80-90
Manure liquids and solids (diluted less than 50%) held
in waste storage pond
65-80
80-95
80-95
Manure and bedding held in roofed storage
65-80
80-95
80-95
55-70
80-95
80-95
Manure and bedding held in unroofed storage, leachate
lost
55-75
75-85
75-85
Manure stored in pits beneath slatted floor
70-85
85-95
85-95
70-85
90-95
90-95
80-90
90-95
90-95
70-85
90-95
90-95
Manure treated in anaerobic lagoon or stored in waste
storage pond after being diluted more than 50%
20-35
35-50
50-65
20-35
35-50
50-65
20-30
35-50
50-60
20-30
35-50
50-60
Source: USDA, 1992.
Table 11-10. Liquid manure nutrient concentrations in pit storage.
Manure
Producedb
1000 gal/yr.
lb nutrient/1000
Nutrients
gal/yr (% decrease from Table ll-l)a
Animal Category
Nitrogen
Phosphorus
Potassium
Farrow, per sow and litter
1.400
15.00
(42%)
5.24
(24%)
9.13
(23%)
Nursery, per pig cap.
0.130
25.00
(44%)
8.44
(31%)
18.26
(22%)
Grow-fin, per pig cap.
0.530
32.75
(32%)
11.55
(28%)
22.41
(32%)
Breed-gestation, per sow cap.
0.500
25.00
(47%)
13.55
(29%)
22.41
(23%)
Dairy cow, per mature cow
6.000
31.00
(11%)
6.56
(9%)
15.77
(32%)
Dairy heifer, per hd cap.
3.000
32.00
(14%)
6.12
(24%)
23.24
(7%)
Dairy calf, per hd cap.
0.700
27.00
(14%)
6.12
(11%)
19.92
(8%)
Veal calf, per hd cap.
0.400
26.50
(17%)
9.61
(20%)
33.20
(12%)
Beef cows, per hd cap.
3.600
20.00
(45%)
6.99
(28%)
19.92
(24%)
Feeder calf (500#), per hd cap.
1.550
27.00
(33%)
7.87
(26%)
19.92
(19%)
Fattening cattle, per hd cap.
3.100
29.00
(28%)
7.87
(26%)
21.58
(13%)
Broilers, per bird cap.
0.010
63.00
(19%)
17.48
(20%)
24.07
(9%)
Pullets, per bird cap.
0.011
60.00
(19%)
15.30
(23%)
24.9
(15%)
Layers, per bird cap.
0.017
60.00
(16%)
19.67
(14%)
23.24
(5%)
Tom-turkeys, per bird cap.
0.034
53.00
(38%)
17.48
(53%)
24.41
(9%)
Hen-turkeys, per bird cap.
0.028
60.00
(35%)
16.61
(60%)
26.68
(7%)
Ducks, per bird/vr.
0.030
22.00
(41%)
6.56
(67%)
6.64
(42%)
a Percentage decrease based on decrease mass (i.e., accounts for increased dilution) from Table 11-1.
b Includes dilution water.
Source: after Jones and Sutton, 1994.
decreases range from 65 to 80 percent, phosphorus decreases range from 50 to 85 percent, and potassium decreases
range from 35 to 50 percent. (Recall that phosphorus and potassium decreases for lagoons are related to sludge
accumulation and nitrogen losses are due to volatilization.)
Fulhage (1994b) compared nutrient production from dairy lagoon/flush and slurry systems (see Tables 11-12 and 11-
13). Based on an economic analysis, Boland et al. (1997) found that swine operations should use storage and
application systems that minimize the cost of handling the manure. They also found that for deep pit systems
11-10
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Table 11-11. Liquid manure nutrient concentrations in anaerobic lagoons.
Animal Category
Manure
Producedb
1000 gal/yr.
lb nutrient/1000
Nutrients
gal/yr (% decrease from Table ll-l)a
Nitrogen
Phosphorus
Potassium
Farrow, oer sow and litter
2.100
4.10 (16%)
0.874 (81%)
1.660 (79%)
Nursery, oer me cat).
0.220
5.00 (81%)
1.398 (81%)
2.656 (81%)
Grow-fin. oer me cat).
0.950
5.60 (19%)
1.639 (82%)
3.486 (81%)
Breed-gestation, per sow cap.
0.900
4.40 (83%)
1.857 (83%)
3.320 (79%)
Dairy cow. oer mature cow
11.000
4.20 (78%)
0.765 (81%)
2.490 (80%)
Dairy heifer, oer hd cat).
6.000
4.25 (77%)
0.874 (78%)
2.490 (80%)
Dairy calf, oer hd car).
1.200
3.00 (84%)
0.437 (89%)
2.075 (84%)
Veal calf, oer hd car).
1.000
3.00 (77%)
0.437 (91%)
2.490 (84%)
Beef cows, oer hd car).
6.000
4.00 (82%)
1.311 (78%)
3.320 (79%)
Feeder calf (500#). oer hd car).
2.700
4.00 (83%)
1.311 (79%)
2.905 (79%)
Fattenine cattle, oer hd car).
5.300
5.00 (79%)
1.748 (72%)
4.150 (71%)
Broilers, oer bird car).
0.016
8.50 (83%)
1.879 (86%)
2.905 (83%)
Pullets, oer bird car).
0.017
8.50 (82%)
1.748 (86%)
2.905 (85%)
Layers, oer bird car).
0.027
7.00 (84%)
1.748 (88%)
2.905 (81%)
Tom-turkevs. oer bird car).
0.060
8.00 (84%)
1.748 (92%)
3.735 (75%)
Hen-turkevs. oer bird car).
0.060
8.00 (82%)
1.748 (91%)
3.320 (75%)
Ducks perbird/vr
0 035
5 00 f84%)
1311 (97.%)
?. 075 (19%)
a Decrease based on decrease mass (i.e., accounts for increased dilution) from Table 11-1. b Includes rainfall and dilution water.
Source: after Jones and Sutton, 1994.
Table 11-12. Nutrients produced for a dairy lagoon system.
Nutrients produced
(lbs/yr)
Herd Size
100
200
300
500
750
1000
NH4-N
2623
3912
4876
7130
9384
11960
Organic N
1312
1956
2438
3565
4692
5980
P
1994
2973
3710
5425
7140
9100
K
6838
10198
12770
18600
24480
31200
Source: Fulhage, 1994b
Table 11-13. Nutrients produced for a dairy liquid manure tank system.
Nutrients produced
(lbs/yr)
Herd Size
100
200
300
500
750
1000
NH4-N
7027
14054
21031
35135
52703
70270
Oreanic N
11225
22450
33675
56125
84188
112250
P
4212
8424
12636
21060
31590
42120
K
15444
30880
4633?.
117.7.0
115830
154440
Source: Fulhage, 1994b.
almost four times as much land was needed when applying manure based on phosphorus rather than nitrogen; 2.5 and
1.7 times as much land would be needed for liquid tank and lagoon systems, respectively. These differences are due
to less ammonia volatilization in deep pit systems and solids settling in lagoons.
A field study of Missouri swine lagoon surface-to-volume ratios found that large swine lagoons have significantly
higher TKN concentrations than small lagoons, and lagoons with specific surface areas of 0.0221 and 0.0498 m 2/kg
pig exhibited average TKN levels of 1,300 mg/L (300 lb/acre-inch) and 550 mg/L (12 lb/acre-inch), respectively.
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This suggests that land application of treated swine manure might need to be based on the design and performance
characteristics of the lagoon rather than animal weight alone (Fulhage, 1998b).
Laboratory studies using a two-stage anaerobic sequencing batch reactor (ASBR) system were conducted on swine
and dairy manure. Volatile solids were reduced by 54.7 percent for swine waste and 26.1 to 47.5 percent for dairy
waste. Odor was negligible and H2S and mercaptans were not detectable after anaerobic treatment for both waste
types. Thermophilic-mesophilic treatments removed 6 to 15 percent more volatile solids than mesophilic-mesophilic
treatments, indicating that a temperature-phased ASBR might be an attractive modification for treatment of animal
waste (Tao et al., 1998).
A pilot swine waste treatment system composed of two upflow aerated biofilters in series with two polishing tanks
also in series was tested for 1 year. The plant, with a 8 m3/day capacity, removed approximately 88 percent BOD, 75
percent COD, and 82 percent suspended solids from flushed swine wastes containing 5.7 kg COD/day per m3 of
biofilter media. Total Kjeldahl nitrogen, total ammonia, and total nitrogen concentrations were decreased by 84, 94,
and 61 percent, respectively although increased organic matter and lower temperatures decreased the efficiency of
the system (Westerman et al., 1998).
Due to the lack of adequate land disposal area in Arizona, Blume and McCleve (1997) increased the evaporation of
wastewater from a 6,000 hog flush/lagoon treatment system by spraying the wastewater into the air. A solid set
irrigation system was aligned on top of plastic ground covers so that any non-evaporating water could be collected
and directed back into the lagoon. Although information on volatilization was not available, the evaporative increase
from spraying and pond evaporation was 51 percent greater than pond evaporation alone.
Table 11-14 is a cost comparison (1994 dollars) of storage systems in Minnesota. This table is based on the same
amount of storage required for different systems. They are approximations based on the following assumptions:
< Storage is for manure and runoff.
< The basins are excavated and no drainage problems exist.
< All systems, excluding the round tanks, are square.
< The clay liner is 2.4 feet thick and material for it is available on site.
< Two agitating pads plus a runoff ramp are included in all the basin cost comparisons.
< Collection pits, pumps, or pipe that may be needed for transfer to storage systems are not included.
< $3,000 has been included for components such as waterways, diversions, and fences.
Table 11-14. Cost comparison (1994 dollars) of manure systems in Minnesota.
System
Investment
Earthen basin
$10,000 -$50,000
Waste storage structure, concrete/below ground
$60,000 - $75,000
Prestressed concrete above ground storage
$60,000 - $75,000
Solid manure stacking slab & runoff pond
$40,000 - $55,000
Slurry storage/steel tank
$100,000 -$150,000
Used slurry
$70,000 - $80,000
Rotational grazing (if the producer has enough
acreage)3
$40 - $100 per acre, includes water system, fencing,
and livestock lanes
aData based on average cost obtained throughout Minnesota by the NRCS Office, St. Paul, USDA
Source: Reichow, 1995.
System costs would also include the cost of pumping versus hauling, which includes labor costs as well as agitation
requirements, capital, maintenance, and fuel costs. For example, Reichow (1995) estimated that for a dairy operation
with a 34,000 ft3 storage basin and a 1,000 gallon tank it would take 255 loads to empty the basin. Assuming 17
minutes to fill the tank, apply the manure to the field, and return it would take a total of 72 hours to empty this basin
at a cost of between $1,600 and $2,500 (Reichow, 1995).
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NCSU (1998) estimates the typical costs of constructing a lagoon to be $0.04/ft3. Pit storage was estimated at
$0.82/ft3. In an example analysis, NCSU (1998) estimated the annual storage and treatment cost to be $1.69 and
$0.42 per hog finished for a slurry (pit storage) system and an anaerobic lagoon, respectively. Related transportation
and land application costs were estimated at $1.164 and $0,514 per hog finished for a slurry and lagoon system,
respectively. Additional costs related to lagoon sludge removal and reduced income for a spray field combined with
the value of fertilizer saved for a slurry system yielded a net cost of $0,416 and $1.10 to $2.00 per hog finished for
slurry and lagoon systems, respectively.
Liang and Paquin (1997) have designed a variety of bioreactors for small swine operations made of high density
polyethylene (HDPE) in Hawaii that are inexpensive, mobile, and capable of aerobic, anaerobic, or facultative waste
treatment. The main limitations are due to the strength of HPDE which restricts the size of storage facilities
(maximum 4 ft high and 16 ft wide). Costs of HDPE facilities are $0.45 per gallon compared to typical cone bottom
poly olefin tanks ($1.8/gallon) or concrete block ($2/gallon).
11.5 Solid-Liquid Separation
Physical treatment by separation of solid and liquid wastes is used to minimize the solids loading to lagoons, to
facilitate reuse of the liquid in a flushing system, to reduce clogging of irrigation sprinklers, or when volume
reduction aids treatment. Separation can be achieved through sedimentation (gravity), centrifuging, or screening
(Day and Funk, 1998). Settling basins are common when runoff is collected from feedlots or similar areas. If the
detention time in a basin is about 30 minutes, 50 to 85 percent of the solids can be removed from runoff in the
settling basin before passing to a retention pond. Lorimor et al. (1995) found that settling basins removed 64.2
percent of total solids below an earthen lot and 39 and 52.9 percent of total solids below two concrete feedlots
studied in Iowa.
Sedimentation was also demonstrated when Stowell and McKenney (1998) analyzed dairy wastewater from an Ohio
second-stage storage pond to characterize solid content in flushwater used to clean manure from dairy facilities.
Total solids were found to range from 0.94 to 3.17 percent as water flowed from the first to the second storage pond.
Solids in the second pond ranged from 1.045 to 3.21 percent for the top 1 m of water, 2.15 to 4.12 percent for the top
2 m, and 3.17 to 5.81 percent for the full pond depth.
The most common mechanical separation methods include (in general order of increasing cost): static inclined
screens, vibrating screens, belt pressure rollers, screw presses, rotary strainers, vacuum filters, and centrifuges. In a
study by Shutt et al. (1975, cited in Day and Funk, 1998), a static inclined screen, a vibrating screen, a liquid
cyclone, and a settling chamber were evaluated. Using flushed swine waste, the static inclined screen removed 35
percent of total solids while the vibrating screen and cyclone removed 22 and 26 percent, respectively. Chiumenti et
al. (1987, cited in Day and Funk, 1998) compared a horizontal decanter, vertical decanter, centrifugal separator,
rotorpress, and an experimental pressure filter using cattle manure. They found that the horizontal decanter achieved
81 percent total solids removal and the centrifugal separator removed 32 percent of total solids. In another study, a
vibrating screen separator was used to increase solids content from a flushed swine waste from 3 percent to 5-10
percent to optimize anaerobic digestion and methane production (Holmberg, 1983). A dairy manure solids
separation research facility was installed in Sessums, Mississippi for an alley-flush type waste removal system with
free stalls bedded with sand. A gravitational settling basin (GSB) alone or in combination with a mechanical screen
separator (MSS) installed upline were used to separate solids whereby the effluent was transferred to a three stage
anaerobic/facultative lagoon system. The objective was to separate manure solids, sand, and liquid, although some
manure was collected in the GSB even with MSS treatment. End product nutrient concentrations were not affected
by either treatment scenario (Burcham et al., 1997). Fulhage et al. (1998) found that an inclined, stainless steel bar
screen type separator for a 160-cow freestall barn removed 45.5 percent of dry matter, 50.1 percent of volatile solids,
17.1 percent of total Kjeldahl nitrogen, 8.28 percent of ammonia-N, 11.0 percent of phosphorus, 9.93 percent of
potassium, and 19.0 percent of organic-N. The separated solids had a 23.1 percent dry matter content.
Metal salts such as aluminum sulfate and calcium and iron salts can also be used to precipitate solids. Polymers such
as polyacrylamide (PAM) can be used to precipitate nutrients. PAM has been demonstrated to remove 80 percent
TSS, organic nitrogen, and phosphorus. PAM costs $2.50/kg for use in solid-liquid separation. Henriksen et al.
11-13
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(1998) evaluated several flocculating agents and ion exchange to separate liquid swine manure. It was possible to
flocculate 14-day old manure, but fresh swine manure was difficult to flocculate at best.
A screw press separator was installed at a 6,400-head swine facility in South Carolina to examine the removal of
solids and nutrients from liquid waste. The separator, an alternative to strict gravity separation, had a 0.5 mm screen
and 40 kg weights on each pressure plate arm. It was determined that the screw press was capable of removing total
solids, volatile solids, TKN, organic-N, and total P by 16, 21, 12.5, 16, and 16 percent, respectively, from pit-
recharge buildings with pre-settling (Chastain et al., 1998).
A mobile tangential flow separator (TFS) system was tested using chemical amendments to recover swine waste
solids and phosphorus in North Carolina. The system reduced phosphorus from pre-screened flushed waste by
greater than 90 percent when lime, ferric chloride, and polymer were added. Anaerobic lagoon liquid phosphorus
was reduced by approximately 80 percent. End products were 25 percent sludge by volume with total solids of 4 to
5 percent (Westerman and Bicudo, 1998).
Some Asian pig producers separate the solid and liquid fractions of manure at the source (Tengman, 1997). An
example of such separation occurs in an under house pit where the floor under the slats is sloped or v-shaped. The
solids are scraped and the liquid fraction either flows by gravity or is pumped to storage. Such practices are being
studied and gradually implemented at facilities in the United States. The solids fraction contains over 90 percent of
the phosphorus and 37-76 percent of the nitrogen. The solid fraction (65 percent moisture, 14:1 C:N ratio) is about
one-third of the total manure mass, and allows for increased economical transportation distance of manure.
Mechanical separators range from less than $20,000 to well over $100,000 although some operations might be able
to erect their own version of a functional separator for a fraction of the cost. Other costs include power
requirements, labor, and maintenance costs. A portion of the costs can be deferred based on the end product value,
provided that a consumer is readily available. Avoidance costs are also present if the liquids and solids are land
applied due to the concentrating of nutrients, the reduction in volume of solids, and reduction and ease of application
of the liquids. One study (Bio/Resource News, Spring 1995) comparing separation with land application determined
the cost per gallon of separating pig slurry was $0,005 while the cost per gallon of land spreading was $0,017.
11.6 Anaerobic Digestion
Anaerobic digestion is a biological process that decomposes organic material in the absence of air. During the
decomposition process, biogas, which is a mixture of about 70 percent methane and 30 percent carbon dioxide is
given off. Biogas contains about 60 percent of the energy value of the same amount of natural gas. In temperate to
warmer climates, some lagoons are operated anaerobically with a synthetic cover. An existing lagoon that is covered
can only digest manure containing less than 2 percent solids. More sophisticated equipment can be used, such as a
complete mix digester, to process manures containing 3 to 8 percent solids. Plug flow digesters can handle dairy
manures up to 11 percent solids, producing around 40 ft3 of methane per cow per day (USEPA, 1997). Anaerobic
digestion provides both odor and BOD reduction. In fact, a plug flow operation can produce up to a 90 percent
reduction in BOD, more than 99 percent reduction in pathogens, and up to 95 percent reduction in solids. It also
converts up to 70 percent of organic nitrogen to ammonia, a more available form for crop uptake. What remains is a
semisolid effluent that is relatively odor-free and contains all the nitrogen, phosphorus, and potassium originally
present in the animal manure (Day and Funk, 1998 and USEPA, 1997). In these systems, a storage lagoon is
provided following anaerobic treatment and prior to final use or disposal.
Capital costs for anaerobic digesters can be broken down into the following major components:
c Materials handling, including equipment to move material into and out of the digester,
c Digester tanks including heating equipment and mixing equipment,
c Gas handling equipment,
c Electrical generation equipment if used.
11-14
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Yang and Can (1997) investigated an anaerobic swine manure treatment prototype to determine its effects on odor,
byproduct utilization, and wastwater reuse in Hawaii. Initial costs for facility construction are high and profit
margins were decided by the efficiency of biogas electric production and wastewater irrigation. Profits were
calculated for swine operations greater than 850 pigs. Strict wastewater reuse policies in Hawaii were achieved with
this system by reduction in COD (89 to 95 percent), TKN (82 to 89 percent), and total phosphorus (81 percent) and
little or no odor. An integrated system with anaerobic biofilm digester and intermittent aeration tank was tested for
treatment of swine waste in North Carolina. Using plastic ballast rings as a medium, the anaerobic digester reduced
COD, TOC, TSS, and VSS by 66, 56, 68, and 72 percent, respectively. The aeration tank further reduced organics
and maintained strong nitification; however, no significant denitrification was determined in the intermittent aeration
process (Cheng and Liu, 1998).
Berge and Hansen (1998) describes initial bench-scale experiments to remove ammonia, which inhibits bacteria
activity, from anaerobic digesters. Using household ammonia and citric acid, ammonia removal was 9.58 mg/min/L.
Similar experiments achieved ammonia removal rates of 4.4 mg/min/L from fish processing waste with ammonia
concentrations above 2,500 mg/L.
Three leachbed-UASB closed-loop anaerobic digestion treatment systems were compared in a laboratory study to
test alternatives for poultry mortality disposal (Chen, 1998).
The three leachbeds (Lbs), which carry out the hydrolysis/acidification phase of treatment, differed in their initial
solids contents (4.4, 7.5, 13.3 percent). The UASBs accomplish the methanogenesis phase and serve as a vessel for
continuous inoculum production for the LBs. All systems performed very well with little operational problems, but
overall the system with an initial total solids in the LB of 7.5 percent performed best. After 118 days of anaerobic
digestion in the LB-UASB system, about 86 percent of the poultry mortalities were biodegraded, and methane
accounted for 83.7 percent of the total COD. The LBs accounted for at least 63 percent of the bioconversion in each
system. System capacity can be further expanded by scheduling several LBs in sequence for one UASB in order to
fully exploit the UASB potential as a high-rate digestor.
Zucker et al. (1997) used EPA's Ag Star software to identify the cost effectiveness of anaerobic digestion for
methane and electricity production for several independent dairy farms in the York, NY area and with a
conglomerated manure facility. Inputs for the Ag Star model, such as farm type, size, location, and electrical
expenses, were obtained by a survey from 30 dairies located in the area. Break-even costs are dependent on the
value of electricity and any additional benefits from the anaerobically digested manure. Economies of scale apply to
farms of 850 or more cows.
Williams et al. (1998) describe the design, construction, and anticipated operation of a lagoon-type methane recovery
system for a California dairy facility expected to have 300 to 600 cows. The 16,000 cubic meter lagoon will be
covered with a flexible membrane designed to float on the surface. Assuming 350 animals create an average of 370
cubic meters of biogas per day, a gas collection system is predicted to produce 25 kW using a micro-turbine electric
generator. This system is estimated to annually produce 170,000 kWh and 77,000 KJ of hot water worth $16,000.
An anaerobic digester (anticipated 1000 cows) and a wetland system (anticipated 300 cows) were investigated as
treatment alternatives for dairy waste in New York. The anaerobic digester was designed for monetary returns on the
$365,000 initial cost through electric generation ($24,000 per year) and for sale of solids collected as a nutrient
supply ($32,445 per year). The wetland treatment system initially cost $94,919 and obtained $6,000 per year on
solids sold. Wright and Perschke (1998) determined that both systems were feasible options for treatment of dairy
waste.
Overall, the costs of anerobic digesters vary with the size and type of system to be used. A digester for a 120-head
dairy or a 150-head hog operation should cost between $125,000 and $175,000. Economic viability for anaerobic
digesters is strongly dependent on the operator's ability to use the biogas and the price placed on odor control cost
avoidance (Minnesota Dept. of Agriculture, 1995). Several operations have installed some form of digester for gas
recovery. In general, only larger facilities have installed a large-scale digester, but a few hundred dairy head have
been shown to be sufficient for a reasonable return (EPA, 1995). In 1993 dollars, capital and installation costs for
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gas recovery equipment ranges from $100 to $380/head for dairy and $40 to $170/head for pigs. The gas utilization
equipment for a 5,000-head hog farm is about $21/pig. Annual operating and maintenance costs range from $2 to
$6/head for complete mix digesters, and about $4/head for plug flow digesters. At $0.07/kWh electricity costs,
annual benefits are estimated at $8/head for dairy, $13/head for pigs, and up to $34/head for a complete mix digester.
According to an AgStar Fact Sheet (EPA, 1995), a 500-head dairy operation installed a covered concrete lagoon to
collect methane for both electrical energy and heat. The manure collection method for this facility is tractor
scraping. The facility experienced an operating and maintenance (O&M) cost reduction of $53,000 with an annual
rate of return of 21 percent. Another 270-head dairy installed a complete mix digester for $500,000 with an annual
operating cost of $4,125 (EPA, 1997). The farm sells gas that is equivalent to 17,000-18,000 gallons peryear of fuel
oil to a neighboring retirement home and heats its digester with the biogas, saving $10,000 per year. The resulting
land-applied effluent is valued at $25,000 per year. In addition, a 1,000-sow farrow-to-finish operation covered part
of an existing lagoon to collect methane for electricity and heat. Their O&M costs decreased by $36,000 with a 34
percent annual rate of return. Another 1,500-sow farrow-to-finish operation installed a complete mix digester for
$250,000 and demonstrated reduced O&M costs of $65,000 per year. Table 11-15 provides additional examples
documented in EPA's AgStar program.
Table 11-15. Comparison of digester costs.
Size and Type of
Operation
Type of Digester
Costs
Benefits/Break-even
300 sow farrow-to-
feeder
covered lagoon
$16,000 capital
<$500 O&M
12-13 gallons propane equiv/day
700 sow farrow-to-
finish
covered lagoon
provides 80-90% of electricity demand (about
$70,000 peryear); reduces dust, odor, flies
1,000 sow farrow-to-
finish
partial cover on
existing lagoon
$36,000 electricity & heat (34% annual rate of
return)
1,500 sow farrow-to-
finish
complete mix digester
$250,000 capital
$65,000 electricity & heat per year (4 to 5
years)
150-head dairy
covered lagoon
$44,000 capital
$9,350 peryear hot water (4.9 years)
270-head dairy
complete mix digester
$500,000 capital
$4,125 O&M
$10,000/year heat + sells 17,000-18,000 gal/yr
fuel oil equivs. (Land applied effluent valued
(a), $25,000/yr.)
350-head dairy
plug flow digester
$185,000
$40,000/yr. Electricity (solids sold blended as
soil amendment)
400-head dairy
plug flow digester
$200,000
$51,000/year electricity & heat (digested solids
sold as mulch for $6,000/yr.) Reduced clean-
outs saved $9,000/yr. (5 years)
500-head dairy
(scraped)
covered concrete
lagoon
$53,000 electricity & heat; fewer lagoon
cleanings; solids sales (21% annual rate of
return)
1,000-head dairy
covered lagoon
$254,000 capital
$10,000 O&M
$56,000 electricity (5.5 years, 18% rate of
return)
5,000-head dairy
(manure from 1,500 to
2,000 cows)
3 plug flow digesters
$300,000 $12,000 to
$15,000 O&M
$125,000 to $160,000/yr. energy (6 years)
Source: USEPA, 1995, 1996, 1997a, 1997b.
11.7 Composting
Composting turns potentially nuisance-causing waste products into a more easily handled and valuable commodity.
It is an excellent soil conditioner, and when applied to cropland, it adds organic matter, improves soil tilth, reduces
fertilizer requirements, and reduces the potential for soil erosion (NRAES, 1992). Composted material also contains
some natural plant disease suppression characteristics.
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Although the composted product's value is higher than raw manure, composting can be relatively expensive and
labor intensive. As a result, agricultural operations usually only consider composting when a marketable product is
created that will remove excess nutrients from the farm. If transportation distances are long, composting might
reduce transportation costs since composted material is typically one-half the uncomposted volume. Compost can
also be used for the disposal of dead animals, yard waste from municipalities, sawdust and wood chips from lumber
mills, food wastes from food processing facilities, paper mill sludge, etc. In some cases compost operators can
charge a tipping fee for disposal of the wastes that would otherwise be disposed in a land fill, improving the
economics of composting.
Some compost piles are turned or aerated regularly to maintain optimal oxygen concentration and temperature.
Other composting systems are mechanized and do not require turning, but capital investment and maintenance costs
are higher. Windrow composting involves placing the manure mixture in long, narrow piles (windrows) that are
turned on a regular basis. The windrows are approximately 3 feet high and 10-20 feet wide for dense manure. The
shape of the windrow depends on the turning equipment used. The turning frequency depends on compost materials
and climatic conditions. Passively aerated windrows eliminate the need for turning because air is supplied through
open-ended, perforated PVC pipes embedded in the windrow. Air flow is maintained through two rows of 0.5-inch
holes to control the heat produced by the decomposition process. Windrow materials should be thoroughly mixed
when constructed and built on a base of straw, moss, or compost to absorb moisture and provide insulation. Aerated
static piles are similar to passively aerated windrows, except that air is forced into the pile using pipes with blowers.
This method allows for larger piles and turning is not required. In in-vessel composting, composting materials are
confined within a building, container, or vessel. Forced aeration and mechanical turning techniques are used to
speed the process (Minnesota Dept. of Agriculture, 1995).
Different types of in-house deep litter manure management systems were tested in a 100,000-chicken commercial
high-rise layer operation in Georgia. Composting was conducted using raw manure, a manure and leaf mixture, and
manure and woodchip mixtures of 0.12 m, 0.25 m, and 0.38 m. The in-house composting was found to more
efficiently reduce weight and volume of wastes than conventional methods of stacking manure under the house.
Woodchip and leaf manure compost displayed similar properties, decreasing moisture content and concentrating
nutrients compared to the raw manure. The composting process was found to be enhanced by regular turning of the
manure mixtures (Thompson et al., 1998).
Five treatment combinations of composted cattle feedyard manure and liquid phosphate (10-34-0) were applied to
provide 100 percent of the phosphorus requirement for full-season corn hybrid crops. Five replicates were tested for
each treatment. No significant difference was determined between corn yields in treatment-by-treatment
comparisons, indicating that composted feedlot manure may provide adequate substitute for chemical fertilizers.
These findings may have been confounded by water limitations during the growing season and conclusions need to
be verified (Auvermann and Marek, 1998).
Hong et al. (1997), in an unreplicated study in Ohio, measured ammonia concentrations from dairy manure and rice
hauls composted with continuous aeration rates of 53, 73, and 90 L m 3 min"1. Temperature and ammonia
concentrations peaked 48 days after initiation of aeration and then declined steadily, approaching an asymptote after
150 hours. The highest ammonium removal occurred at the 73 L m 3 min"1 aeration rate.
The feasibility of using sawdust and chopped fescue hay as a low cost or waste carbon source to compost with
separated swine manure solids was investigated using 21 L vessels and bin composting units. Manure and fescue hay
produce the lowest C:N ratio in both small (11.5) and large composting units (26). The percent TKN (1.84 percent)
and K (1.84 percent) were also higher for the fescue hay matrix. Percent phosphorus was greater for the sawdust
material (0.84 percent). Temperature trends were used as indications of biological activity. Although labor
intensive, composting manure with a carbon source was recommended because the product was easy to transport,
odor stable, and appropriate for transport through residential areas (Hoehne et al., 1998).
The effect of intermittent aeration on composting swine waste was studied to determine changes in ammonia
emissions and dry matter loss. Continuous and intermittent aeration treatments (4 each) were conducted on
composting hog manure amended with sawdust in pilot-scale 200 L vessels run for a three week trial. Internal
temperature was maintained in the continuous sequence using feedback control air flow fans while intermittent
treatments received a cycle of 5 minutes of airflow and 55 minutes of rest. Ammonia emissions were 39 percent less
11-17
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from the intermittent aeration treatments, with nitrogen loss as ammonia-N consisting of 25.9 and 14.3 percent for
continuous and intermittent aeration, respectively, although these differences were not statistically significant. Dry
solids loss and other physicochemical properties were similar between the two treatments. It was concluded that
intermittent aeration may be a practical method to reduce nitrogen loss and ammonia emissions during composting of
swine manure with sawdust (Hong et al., 1998).
To reduce the bulk of swine manure slurries, Panti and Kinsman (1997) measured water loss after irrigation of swine
manure slurry on existing swine manure:straw (3:1 w/w) compost piles when pile temperatures exceeded 50 eC.
After 60 days, water in the control pile (with no added irrigation) was reduced by 75 percent. Including the
additional water added to the compost pile by irrigation, the treatment piles removed about 340 percent of the water
compared to the control pile during the same period.
Two waste products from a municipal and a dairy source were composted in the lab under controlled temperature
and air flow rates. Maintaining high and constant temperatures (50 to 70 eC) destroys pathogens and accelerates
decomposition. Air flow as low as 4 L/min was sufficient for decomposition of waste sources (Hall and
Aneshansley, 1997).
The influence of ammonium sulfate (AS) amendments intended to increase nitrogen content in poultry manure was
studied in pilot scale reactor vessels. Partially composted poultry waste (30 to 40 days old) received 80.6 gAS/kg
compost (wet basis) and were monitored for two weeks. Treatments receiving AS retained 81-100 percent of the
initial nitrogen content and demonstrated a 1 percent increase in final nitrogen concentration over non-amended
compost. Sequential additions of AS exhibited greater ammonia emissions than a one-time application. Carey et al.
(1998) concluded that ammonium sulfate could be added in one application to improve nitrogen content while
experiencing minimal ammonia loss.
To compost swine carcasses in Missouri, Fulhage (1998) recommends the addition of 2.8 m3 (100 ft3) sawdust per
450 kg (1000 lb) of swine carcass (6 months total composting time). He estimated that one-third of the nitrogen and
one-half of the dry matter and water in the raw ingredients are lost as products of respiration when swine are
composted with sawdust, leaving 18 lb N and 2000 lb of finished compost (wet weight) per 1000 lb of animal
carcass. These estimates are useful in sizing the soil-plant filter for carcass composting and in determining the land
area needed for disposing of the compost product based on its nutrient content and the desired application rate.
Ekinci et al. (1998) investigated poultry litter composting as a function of the C/N ratio and pH of starting materials.
They mixed short paper fiber, which has a high C:N ratio (> 200) and is slow to decompose, with broiler litter, which
has a low C:N ratio (10-12) and emits too much ammonia when composted alone. An evaluation of ammonia
emissions showed that NH3-N losses decreased substantially as the C:N ratio increased. NH3-N losses decreased
significantly at pH > 7 and increased significantly at pH > 8. They also found that the initial temperature of the
compost material (> 1°C) did not significantly affect the time needed for the material to reach the desired
temperature of 45°C.
When assessing the cost of using composting as part of a waste management system, it is necessary to consider the
availability and price of raw materials, the amount of land available for composting, the expected markets for the
finished compost, local costs of labor and fuel, and location factors. There are also different composting methods.
Composting equipment costs for starting an on-farm composting operation can range from $20,000 to $125,000 and
higher, depending on the size of the operation and the level of technology chosen. Some smaller operations may use
existing equipment, however, to help keep start-up costs low. Table 11-16 is a comparison of their costs. Note that
costs include labor and equipment expenditures, and may vary widely depending on the size of the operations and the
materials being handled.
11.8 Odor Control
Much research in the past decade has been aimed at odor (and dust) control. The extent to which odor control
practices influence ammonia volatilization is important because the amount of ammonia volatilized can be
significant. For example, ammonia emission from a new, grow-finish swine facility with a 2.4 m deep pit was
11-18
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Table 11-16. Comparative costs of composting methods.
Composting Method
Estimated Cost (1995 dollars) per Ton
of Incoming Material
Windrow composting using a loader for turning
$5-$10
Windrow composting using specialized turners
$15 -$30
Aerated static pile systems
$20 - $50
In-vessel systems
$50-$100
Source: Minnesota Dept. of Agriculture, 1995.
measured from June 26 through September 25, 1997. Gaseous concentrations, temperature, and pig number were
continuously recorded. The measured 122 ±8 g-ammonia/day/500 kg pig weight emission rate was higher than
published literature values. This was likely the result of warm weather and high ventilation rates. The flux of
ammonia from the building was directly proportional to ventilation rate, pig weight, and indoor temperature (Ni et
al., 1998b). The 7.0 ± 0.9 g-hydrogen sulfide/day/500 kg pig weight emission rate measured was also higher than
published literature values (Ni et al., 1998a). Recent research has tended to focus onbiofilters and waste
amendments. The remainder of this section describes some of this work.
Four biofilters constructed of yard waste compost and brush chips were tested to determine the effect of residence
time on swine waste treatment. Odor was reduced by 87 and 91 percent for 4- and 8-second residence times,
respectively. Hydrogen sulfide emissions were reduced 96 and 97 percent and ammonia emissions were reduced 74
and 82 percent. No significant difference between the 4- and 8-second test biofilters was determined. In conjunction
with information from other studies, the current recommended minimum residence time for an open face biofilter is 4
to 5 seconds (Nicolai and Janni, 1998).
Chen et al. (1997) identified the presence of purple sulfur bacteria in 4 of 8 swine lagoons sampled. Purple sulfur
bacteria are known to reduce odors from lagoons, but the reasons for their presence and growth are speculative.
Characteristics of lagoons with and without purple sulfur bacteria indicated that amounts of alkalinity, BOD,
salinity, or ammonium were significantly lower in purple lagoons. Sulfide concentrations were not significantly
different in purple and non-purple lagoons.
A laboratory study to determine the odor reduction of swine and dairy manure was conducted using algae, powdered
lava rock, a mixture of algae and powdered lava rock, and various thicknesses of rapeseed oil surface coatings. The
algae extract increased ammonia release by 13 percent, while lava rock and the mixture reduced ammonia release by
3 percent and 2 percent, respectively. Rapeseed oil thickness of 24, 40, and 60 L/m2 reduced ammonia emissions by
56, 53, and 64 percent and odor release by 67, 75, and 78 percent, respectively (Btischer et al., 1997).
A plenum covered with dairy and poultry compost and kidney bean straw was established outside an exhaust fan
(2,200 cfm) from a manure storage pit under a swine farrowing barn in Minnesota. Average annual reductions of
odor (78 percent), H2S (86 percent), and NH3 (50 percent) were measured between the inside and outside of the
biofilter. The cost of this biofilter based on a 10-year life and compost/straw replacement frequency of 3 years was
$0.28/piglet produced (Nicolai and Janni, 1997).
Amendments of materials to dairy waste during composting was investigated to determine their influence on odor
emissions. Rice husks (control) and finished dairy waste compost mixed with rice husks (treatment) were added to a
stainless-steel tank in a 1:1 weight ratio with dairy manure. The odor emission rate was reduced by 64 and 40
percent between the control and treatment during the first and second weeks, respectively. Sulfur emissions were
reduced by 54.8, 28.9, and 17.5 percent for methylmercaptan, dimethyl sulfide, and dimethyl disulfide, respectively.
There was no significant reduction in average ammonia emissions (Tanaka et al., 1998).
Potassium permanganate, used in municipal and industrial wastewater treatment, has been used to reduce sulfides,
mercaptans, and other odor causing agents in manure storage structures, particularly lagoons. Cement kiln and
power-plant alkaline by-products have also been used to reduce volatilization and odor.
11-19
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The treatment costs of several odor-control chemicals were compared with costs of operating an oxidation ditch.
The oxidation ditch was three times more expensive to treat 1,000 gallons of waste than any of the chemicals
evaluated. The cost of treating liquid manure with hydrogen peroxide at the 12.5 ppm level, which is sufficient to
control sulfides during waste removal and land spreading, was less than treatment with any of the other chemical
agents tested.
The costs of other odor-control chemicals, including Enviro-chem CX, Pit Boss, Micro-Aid, INHIBODOR, OD-R-
ADE, LIQUIDATOR, NOXDOWN, MANU-RX, and De Odorase, range from $22 to $150 per gallon and treat
various quantities of waste. Disk granulates are around $13 per disk and treat 1,000 square feet of surface area, or
$5.40 per pound.
The cost of several oxidants, absorbents, and five proprietary odor control products (TNK, AGCO, Odor Control
Plus, Micro-AID, and SANZYME) for beef feedlot manure ranged from $300 to $600 per acre for treatment during
the odor production season. Feed additives, such as Micro-Aid and OD-R-ADE cost between $1.50 to $3.00 per ton
of complete feed (Minnesota Dept. of Agriculture, 1995).
11.9 Wetlands and Vegetative Filter Strips
Constructed wetlands and vegetative filter strips use plants to take up nutrients and capture suspended solids from
animal waste. Liquids percolate more slowly through wetland soils, resulting in more treatment. For example, Hunt
et al. (1995) found that when swine wastewater containing 14 kg/ha-day of nitrogen was applied to a wetland
combined with a grass filter strip over 95 percent N removal was achieved. Using the waste from a 140 mature
milking cow herd, Moore et al. (1995) achieved fecal coliform removal of 89-95 percent; COD, 53-65 percent;
BOD, 59-72 percent; total solids, 51-56 percent; total Kjeldahl nitrogen, 45-60 percent; and total phosphorus 54-69
percent from a constructed wetland in Oregon.
Three constructed wetlands in Ohio were sampled for the following water quality parameters: P, K, Ca, Mg, Na, Fe,
Mn, Zn, Cu, B, N03-N, NH4-N, S04-S, CI", pH, EC, and TDS (Zimmermann, 1998). The wetlands were used for the
disposal and treatment of milkhouse wash water from dairy farms with 40 to 60 cows. Results showed that the water
in the third cell of the wetland was as good as or better than drinking water quality standards for all the parameters
that had standards except for Fe and Mn. Although the wetlands were an effective method for disposal and treatment
of milkhouse wash water, their effectiveness decreased with age due to overloading of various nutrients. This
decrease in effectiveness can be avoided by removing wetland vegetation before overloading occurs or remedied by
removing both the vegetation and the soil after overloading has occurred.
Buffer strips or vegetative zones serve as a barrier between manure-applied land and waterbodies. Typically, filter
strips reduce runoff volume and velocity due to increased infiltration. This reduces sediment and suspended solids
(SS) by increased deposition, chemical degradation, and transformation. Also, some nutrients are absorbed. In
general, research has shown that filter strips can remove 56-95 percent of the sediment load depending on flow
conditions, soil, slope, and filter width. Nutrient removal tends to be highly variable, although Clausen and Meals
(1989) measured reductions in phosphorus runoff of 86 percent. Forest buffers can also be effective in reducing
nutrients. An 80-90 percent nutrient removal (N,P,K) occurred when dairy feedlot runoff was passed through a
forest buffer (Doyle et al., 1975). Table 11-17 presents filter strip effectiveness in simulated rainfalls (Leeds et al.,
1994).
An experimental study was conducted in Georgia to determine the feasibility of using riparian buffer systems to
remove nitrogen and phosphorus from swine lagoon effluent. Hubbard et al. (1998) showed that the systems were
effective at removing nitrogen, but that phosphorus levels in shallow groundwater increased over time. Nitrogen
concentration increased over time at the top ends of the plots but showed little increase at the bottom ends. An
experimental study was conducted in Virginia to determine the effectiveness of vegetative filter strips at removing
sediment, nutrients, bacteria, and pesticides from surface runoff (Barone et al., 1998). They found that 8.5 m filters
trapped 23 percent of the incoming runoff, 96.7 percent TSS, 91 percent NH 4-N, 84 percent TKN, 96 percent total
phosphorus, 88 percent atrazine, and 92 percent metolachlor. The 4.3 m filters trapped 39 percent of the incoming
runoff, 96.7 TSS, 85 percent NH 4-N, 79 percent TKN, 81 percent total phosphorus, 84 percent
11-20
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Table 11-17. Filter strip effectiveness.
Soil
Texture
Slope
(%)
Flow Conditions
Filter
Width (ft)
Sediment
Removal (%)
Total N (%)
Total P (%)
silt loam
11-16
shallow uniform overland
flow
15
70
54
61
30
84
73
79
silt loam
11-16
concentrated flow
15
83
83
85
30
93
82
87
sandy loam
3-4
shallow uniform overland
flow
15
66
0
27
30
83
48
46
Source: Leeds et al., 1994.
atrazine, and 82 percent metolachlor. The filters did reduce levels of bacteria, although not below primary contact
water standards, and they did not reduce NO 3-N concentration. The authors felt that the small differences in
trapping efficiency between the 4.3 m strip and the 8.5 m strip do not justify the additional cost of installing the
wider strip.
Murphy and George (1997) created an organic (bark bed) filter that flowed into a constructed wetland in
Pennsylvania. The organic filter effectively reduced odors, but residual ammonia concentrations remained too high
for the constructed wetland to remove enough N for discharge into surface waters. Evapotransipiration from the
wetland removed much of the wastewater, and an average of 80 percent reduction in nutrients was observed in both
dormant and growing seasons.
In a replicated study, nine constructed wetlands were amended with nitrogen from dairy manure at loading rates of
5,000, 10,000, and 20,000 kg N ha"1 yr"1 with a 7-day hydraulic residence time. Nitrogen was reduced by about 50
percent for each manure loading rate indicating that the system was not N-saturated. Average COD was reduced by
75 percent. COD and N reduction was enhanced in summer and diminished in winter. Solar radiation, rather than
temperature, controls the rates of N and COD reductions. The cost of this type of system is $3-4/month/animal
(Raman etal., 1997).
11.10 Waste Disposal
Land application is the primary disposal method used by most operators. In general, waste should be applied at
rates, and with a timing, that balance crop uptake with existing soil nutrients. It should be noted, however, that
applying manure in accordance with a sound nutrient management plan does not eliminate nutrients from leaving
fields. In an Iowa field-plot study, for example, Kanwar et al. (1998) found that NO 3-N concentrations in subsurface
drains were significantly higher from manured continuous-corn plots compared with corn-soybean rotation, fecal
coliform bacteria were detected in drain water from both manure and non-manured plots with higher numbers for
manured plots, and N03-N concentrations in subsurface drain water were higher for manure plots.
Depending on the soil characteristics, application method, application time, and weather conditions, the amount of
nitrogen available during the first year of application is variable (see Table 11-18). Table 11-18 shows that
broadcasting without incorporation is the application method that results in the most volatilization and the least
amount of nitrogen available for crop use. Substantial amounts of the available or inorganic nitrogen are lost
through volatilization. This occurs within a few days after application on warmer spring and fall days, or within a
few weeks on winter days. If the manure is incorporated into the soil within a day or two after the broadcasting,
volatilization losses are greatly reduced. Incorporation into the soil also allows thorough mixing of the manure into
the soil, promoting conditions for organic N mineralization. Injection can be done with chisel-type knives, reducing
volatilization losses, but the potential for denitrification losses exist. To avoid these denitrification losses from
conventional injector systems, a sweep knife injection system can be used to reduce the concentrated zones of
manure beneath the soil surface. Instead of creating a vertical band of manure where a knife shank runs through the
soil, a broad horizontal band is created, reducing volatilization potential and encouraging rapid breakdown in the soil
because of the more complete mixing of manure and soil.
11-21
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Table 11-18. Estimated N availability, assuming 50 percent of N is organic N and
50 percent is ammonium N.
Organic
Matter
Application
Time
Soil
Texture
Rainfall
Application Methods
Broadcast
w/o incori)
Broadcast
w/ incori)
Knife
Injection
Sweep
Injection
Low
Fall
Coarse
Low, Norm
30
55
45
55
High
20
45
40
45
Fine
Low, Norm
35
60
50
60
High
30
55
45
55
Spring
Coarse
Low, Norm
40
55
50
55
High
35
50
45
50
Fine
Low, Norm
45
55
45
55
High
45
55
40
50
High
Fall
Coarse
Low, Norm
30
35
50
60
High
25
40
40
50
Fine
Low, Norm
35
55
45
55
High
35
50
40
50
Spring
Coarse
Low, Norm
40
50
50
55
High
35
45
45
50
Fine
Low, Norm
40
50
45
55
High
40
50
40
50
Source: Schmitt, 1990.
In addition to manure's value for macronutrients, manure also provides micronutrients and improves soil condition
as demonstrated in a field study to evaluate the effectiveness of biosolid application for improving water penetration
in heavy clay soils planted with alfalfa and sudangrass in the Imperial Valley, California (Bali et al., 1998).
Applying biosolids at rates ranging from 9-27 Mg/ha prior to the first irrigation in the season resulted in significantly
increased infiltration rates. The increased infiltration was accompanied by a reduction in the irrigation time needed
for a typical application depth of 10 cm. While increasing infiltration might be desirable, it might not be appropriate
for surface irrigated fields due to decreased application uniformity or where increased chemical (e.g., atrazine)
transport is a concern. In a laboratory study, Abu-Zreig and Rudra (1998) found that manure application increased
the quantity and rate of atrazine leaching, especially when manure was applied immediately before a rainfall. The
movement of atrazine was also greater and faster in undisturbed soils than in disturbed soils due to the presence of
macropores. These results indicate that land application of manure results in an increase in chemical transport
processes through the soil. To counter this affect, other researchers added poultry manure/paper pellets to
shrinking/swelling soils to reduce cracking and limit preferential flow of water and solutes to groundwater in a Texas
A&M field study. Organic matter additions are known to improve soil structure, thereby reducing cracking and
allowing a substrate to absorb harmful contaminants. Treatments with pellets adsorbed more atrazine than control
plots (McClure and Munster, 1997). Changes in infiltration rates were not expected until the pellet weathered
further.
In addition to applying manure to agricultural fields, some researchers have proposed application to rangeland
(Phillips, 1998) or investigated application to woodlands. Dickens et al. (1998) are evaluating the long-term effect
on ground water of applying swine lagoon effluent as a seedling tree nutrient source. Loblolly pine, longleaf pine,
and sycamore trees grown on a clayey soil typical of the South Caroline Piedmont region received a variety of weed
control and effluent treatments at a rate of 0, 50, or 100 lb/plant available nitrogen. Tree survival was good, ranging
from a mean of 87.1 percent (loblolly pine) to 93.9 percent (sycamore). Monitoring of soil nutrient status is
currently underway and further studies are planned or in progress using broiler litter, turkey litter, dairy effluent, and
swine effluent on both recently planted and more mature stands. In another study, five species of trees (box elder,
green ash, sweetgum, swamp black gum, later replaced by sycamore due to high mortality, and bald cypress) were
treated with swine effluent in North Carolina to show the effective utilization of nutrients by hardwood species.
Application of swine waste at 200 and 400 lb N/acre resulted in increased survival for all seedling species, except for
sycamore. Tree growth was increased by the 400 lb N/acre treatment for all species except bald cypress; the 200
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lb/acre treatment exhibited no influence on growth. Box elder and green ash appeared to most effectively
accumulate nutrients (Frederick et al., 1998).
There are opportunites to improve manure application technology. It has been estimated, for example, that a
computer-directed liquid-manure applicator with GPS technology could be used for precision manure spreading.
Equipment modifications to exisiting liquid-manure equipment would cost about $5,000. Glancey et al. (1997)
developed a precision spreader for broadcasting solid waste in Delaware to accurately spread a range of manure (1 to
5 tons/acre) on various grid sizes (>0.5 ac) with infrequent calibration. The spreader has computer-controlled
adjustable flow rates and GPS to enable accurate record keeping that facilitates manure application mapping.
Capitals costs for Vee and Tanker spreaders in 1996 in York, New York are listed in Table 11-19 (Wright, 1997).
Table 11-19. Costs (1996 dollars) for vee and tanker spreaders.
Vee Spreader
Capacity,gal
912
1,255
1,621
2,239
3,000
Capital Cost, $
7,500
10,000
12,500
$16,700
20,000
Tanker Spreader
Capacity, gal
2,250
3,250
4,500
5,000
6,000
Capital Cost, $
$9,000
$9,500
$14,000
$15,500
$18,500
Source: Wright, 1997.
Powell (1994, cited in Sweeten, 1998) measured manure harvesting from feedlots of 53 tons/hour using a box
scraper and 87 tons/hour using wheel loaders. In 1985, a survey of contractors in Texas found that farmers received
up to $1.20 or paid as much as $0.60 per ton of manure removed. In 1989, hauling costs were found to be $2.61 per
ton plus $0,055 per ton-mile (Sweeten, 1998). In 1996, manure could be purchased from contractors at about $30
per tractor trailer load for local hauls or $0.85 to $1.00 per mile in Dona Ana County, New Mexico. Other costs for
commercial application of liquid and solid manure are summarized in Tables 11-20 and 11-21, respectively.
A survey on the economics of manure application and fertilizer value was presented to 97 York, New York area
dairy farmers (33 surveys were returned). Although many manure land application systems were identified, some
trends were evident. Farms are spending more money to apply manure than the concomitant cost of commercial
fertilizer. Economies of scale allow large farms to reduce overall manure disposal costs, and analysis of manure and
valuation of the nutrients will further reduce costs. The average cost of spreading manure is $77 per acre while net
returns ranged from $-225 to $37 per acre. For the larger dairies studied, spreading costs were approximately $50
per cow per year or $45 per acre per year. Farms with storage had lower spreading costs despite the additional
precipitation (Wright, 1997).
Ritter and Scarborough (1995) estimated that the annual cost of daily manure spreading in the Chesapeake Bay
Watershed was $198.17, $159.27, and $127.75 per cow for 50-, 100-, and 200-cow dairy herds, respectively. The
estimated annual collection, storage, and disposal costs for a 200-cow dairy herd were $150.59, $158.99, $185.03,
$189.23, $201.07, and $150.88 per cow when using an earthen basin, earthen basin lined, belowground concrete
storage, aboveground storage, aboveground steel storage, and anaerobic lagoon, respectively.
Some researchers have added a nitrate-based solution to lagoons just prior to land application to promote nitrifying
bacteria growth. Additives such as PEG have been added to animal bedding, storage structures, and fields
designated to receive manure. The additives bind nutrients, metals, and organic compounds. In some cases binding
is slowly reversible; in other cases, long-term studies indicate binding is strong or relatively permanent. Other long-
term studies are underway to determine the effects of these additives on the environment.
Aluminum, calcium, and iron compounds have also been used to decrease the amount of water-soluble phosphorus in
poultry manure and to decrease nitrogen loss (Moore et al., 1995). Plots amended with this chemically-treated
manure result in 87 percent lower phosphorus runoff concentrations. One study measured runoff from one-acre
11-23
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Table 11-20. Costs of commercial application of liquid or slurry manure. (Values
include costs of manure mixing, hauling, and land application.)
Hauling and
Umbilical Cord attached
Extra
Location and Method of
Application
to applicator
Charges
Application (if applicable)
$ / gallon
Comments
Iowa"
Broadcast
Maximum
0.011
0.007
0.0025
2 miles free
Average
0.0067
0.0065
0.0012
1 mile free
Minimum
0.003
0.006
0.0005
0.5 miles free
Injection
Maximum
0.012
0.007
0.0025
2 miles free
Average
0.0077
0.0065
0.0012
1 mile free
Minimum
0.005
0.006
0.0005
0.5 miles free
Iowab
0.01
no data
0.0013
1 mile free
Midwest6 (injected)
0.0071
no data
0.0028
Southeast0 (irrigation)
0.0015
no data
no data
North Carolina"1
0.01
no data
no data
Ontario Canada6
0.086
no data
no data
aLorimor, J. 1998. Commercial Manure Applicator Directory, www.ae.iastate.edu/manurdir98.htm
b Livestock Industry Facilities & Environment. 1995. You Can't Afford Not to Haul Manure. Iowa State University, University Extension, Ames,
IA. Pub. No. Pm-1609.
c NCSU. 1998. EPA National Guidelines for Swine and Poultry Waste Management.
d Barker, J.C. 1996. Water Quality & Waste Management. Utilization of Dairy Manure as Fertilizer. Pub. No. EBAE 133-88.
e Ontario Federation of Agriculture. 1994. Best Management Practices: Livestock and Poultry Waste Management. Ministry of Agriculture and
Food, Ontario, Canada.
Table 11-21. Costs of commercial application of solid manure.
(Values include costs of hauling and land application.)
Location
Cost
Georgia3 (average)
$20/ton
Oklahomab
$0.10/mile/ton
Delaware6
$0.08/mile/ton
Maryland"1
90 mile transport
$0.23/mile/ton
150 mile transport
$0.18/mile/ton
afrom Vest, L., B. Merka, W.I. Segars. 1994. Poultry Waste: Georgia's 50 Million Dollar Forgotten Crop.
b from Johnson, G.V. H. Zang, W.R. Ruan, N.J. Basta, and J.A. Hatter. 1889. Animal Waste Management:
Economics of Nutrient Recycling. Southern Soil Fertility Conference, Memphis, TN.
c from Martin, J.H., J.G. Farrel, J.E.A. MacKenzie. 1998. An Analysis of Nutrient Utilization Efficiency by
Agriculture in Delaware's Inland Bays Drainage Basin. Final Project Report. The Center for Inland Bays.
Nassau, DE.
d Parker, D. 1998. Alternative Uses for Poultry Litter. Economic Viewpoints Vol. 3 No. 1. University of
Maryland, Cooperative Extension Service.
watersheds at two commercial broiler farms. The watersheds were equipped with flumes and automatic water
samplers. Untreated poultry litter (control) and litter treated with alum were applied to grass pastures and runoff was
monitored. The runoff concentrations are provided in Table 11-22.
11-24
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Table 11-22. Change in runoff concentrations with alum use, mg/L.
Soluble P
Total P
NH,
Nitrate
TKN
Total K
Total As
Total Cu
Control litter
3.23
4.23
2.14
1.55
4.94
17.6
0.04
0.05
Alum-treated litter
1.05
1.49
2.13
1.80
3.89
12.8
0.09
0.04
Source: Moore, 1998.
Aluminum sulfate has also been demonstrated to decrease runoff of metals such as As, Cu, Fe, and Zn in poultry
litter, whereas Ca and Mg concentrations in the runoff increased (Moore, 1998). Ferrous sulfate was also effective
in reducing soluble P in the runoff from land-applied poultry litter, but is not favored as an option for use inside
poultry houses because chickens might ingest the toxic substance.
11.11 Other Technologies
Throughout the world, research continues in nearly all aspects of animal waste management. This section presents
some of these technologies. In most cases, information discussed here is based on a few studies and further research
is likely needed before these practices could be reliably implemented on a general basis. While it is reasonable to
suspect that a technology proven effective for one animal type and location could be considered for a similar
situation, it would be premature to assume that the technology could be transferred to other animal types and
locations. Finally, exclusion or inclusion from this document does not imply disapproval or endorsement.
< Some countries have been experimenting with digging trenches around fields that accept manure and filling the
trenches with an iron compound. This compound captures phosphorus that runs off the field.
< A two-stage reactor that uses red and green algae has been used to remove nutrients from the wastewater. BOD
removal from 25,000 mg/L raw waste to less than 10 mg/L in the effluent was achieved. Full scale
demonstration of technology on swine waste is being implemented in the New England area. Equipment and
system installation costs are high, approaching $1 million for a 2,500- to 5,000-head facility. A 5-year payback
is estimated using the algae as a feed (protein) source.
< Chemical oxidation processes, particularly ozonation, are used to reduce organics, pathogens, and color in
wastewater. Other oxidants include chlorine and chlorine dioxide, but their use is of concern due to the
generation of trihalomethanes and chlorinated organics. In Japan, pig producers make extensive use of
ozonation to treat urine and wastewater following an under-house pit solid-liquid separation process; the solid
fraction is composted. Ozonation processes are currently being studied at a large scale U.S. farrow-to-finish
operation.
< Microbial inactivation in swine waste was laboratory tested using several coagulants for solids removal followed
by a UV radiation treatment. Four coagulants (two polyacrylamides, ferric chloride, and a polyaluminum
chloride) were used, with the two metal salts lowering total suspended solids most effectively (70-95 percent).
UV exposure did not reduce microbial populations sufficiently for many water reuse activities. It was found that
UV treatment following the polyaluminum chloride application of waste diluted by a factor of 15 was capable of
meeting Hawaii water reuse regulations (Pauin, 1998).
< USDA/ARS has been evaluating encapsulated nitrifiers as part of an alternative treatment sequence for animal
waste. This technology is in use at the Pegasus project in Osaka, Japan. Research on municipal wastewater with
nitrifying microorganisms suspended in a polyethylene glycol resin demonstrated a nitrification rate 2.6-3.8
times as high as activated sludge (the denitrification rate of activated sludge was 1.5 times higher than
conventional biological denitrification processes). Overall, a pilot system combining traditional denitrifying
with encapsulated nitrifiers resulted in nitrogen removal greater than 70 percent and an effluent BOD5 of less
than 20 mg/L (Tanaka, 1991). In another project, removal of ammonia nitrogen from swine wastewater by
nitrifying bacteria was tested in bench experiments with loading rates of 418 mg N/L/day and a hydraulic
11-25
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residence time of 12 hours. Nitrification efficiencies of 95 percent were obtained using nitrifiers encapsulated in
polyvinyl alcohol gel. These encapsulated microbes were then added to a pilot plant built at a North Carolina
swine facility. Nitrification activity increased from 21 to 200 g N/M3/day in 30 days using a 48-hour retention
time (Vanotti and Hunt, 1998).
< In addition to microbial digestion, systems have been developed that use algae (photosynthetic fermentors), fish
(grass carp), or aquatic plants (duckweed, water hyacinths) to remove nutrients from the wastewater. For
example, in a bench-scale experiment on duckweed using swine wastewater, Lemna gibba removed ammonia
and phosphate by 99.8 and 99 percent, respectively, from wastewater in a 1:1 dilution with tap water. Greater
dilution of wastewater did not appear to enhance nutrient removal capabilities (Cheng et al., 1998). The effluent
is used for recycle, or in some cases animal drinking water. The plants are harvested for use as an animal feed.
One system used in India involves integration of a fish pond under the slats of a goat confinement house. Both
the goats and fish are sold, and very little manure management is needed.
< Alternative uses of manure are another option beyond new treatment technologies. Some possibilities that have
not been widely adopted include using manure as a fuel, a commercial fertilizer additive, and an animal feed
component (Steele, 1995). Flachowsky and Hennig (1995) found that poultry and pig excrement can be used as
low-quality feed for ruminants. They also found that deep stacking of poultry litter might destroy potential
pathogens and improve feed value while urea treatment preserved wet pig-slurry solid, and sodium hydroxide
increased digestibility. Manure can also be dried and incinerated, or mixed with cement, kiln by-products, or
glass to create a floor tile product.
< Crystallization or freezing processes have been used to treat wastewater. By turning the wastewater to snow, the
volatile gases are readily stripped from the water. Other contaminants are precipitated from the water in a
process called atomizing freeze-crystallization. In a pilot test program, the meltwater had reductions of 60
percent of the nutrients, and almost 100 percent of pathogens were killed (MacAlpine, 1997). Options to
capture the stripped gases are being explored. The system appears to be especially suitable for colder climates,
where typical bacterial digestion and treatment processes are slowed by the temperature.
< Ion exchange is a process by which one ion is displaced from a insoluble material or resin by ions of a different
species. The process can be operated continuously or in a batch mode. The used resin is regenerated and
reused. The process is used to remove ammonium, some nitrate and nitrite, TDS, and SS. Zeolite, a volcanic
mineral, is frequently used for its cation properties and to reduce odor.
< The thermochemical conversion (TCC) process of altering the chemical structure of organic matter was tested in
a bench-scale processor to change swine waste into oils and gases (He et al., 1998). COD was reduced by 94
percent and 8.5 percent of the volatile solids were converted to oils. It was concluded from these preliminary
results that the TCC process could be an alternative treatment option of swine waste.
11.12 Other Effectiveness and Cost Information
Table 11-23 presents a relative comparison of common waste treatment systems developed by NCSU (1998).
Values of 1 indicate most effective and 3 indicate least effective. Costs are rated as high (H), medium (M), and low
(L).
Table 11 -24 shows the average costs in the state of Pennsylvania for some of the most common manure management
systems. It was compiled by the Bureau of Land and Water Management of the Pennsylvania Department of
Environmental Resources in 1993. The cost data can be highly variable between sources, years, and regions. BMP
costs can also vary between farms.
11-26
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Table 11-23. Effectiveness and cost of waste treatment system components.
Oxygen
Odor
Ammonia
Nitrogen
Phosphorus
Demand
Pathogen
Emission
Emission
System Component
Reduction
Reduction
Reduction
Reduction
Reduction
Reduction
Cost
Covered Reactors
3
2
1
2
1
1
H
Solids Separation
2
2
2
2
2
2
M
Composting
N/A
N/A
N/A
1
2
2
M
Anaerobic Digester
3
2
1
2
1
1
H
Anaerobic Lagoon
2
2
1
2
2
3
L
Aerated Lagoon
2
2
1
1
1
1
H
Sequencing Batch
1
2
1
1
1
1
H
Reactor
Fixed-media Aerated
2
2
1
1
1
1
H
Biofilters
Activated Sludge
1
2
1
1
1
1
H
Source: NCSU, 1998.
Table 11-24. Cost data (1993 dollars) for Pennsylvania state averages for manure management practices.
Management
Practice
Cost3 ($)
Benefits
Maintenance
Requirements
Coordinating
Structures/Practices
Terrace (grassed)
Gradient
Storage
$1.38/LF
$2.20/LF
Slows runoff to allow sediment
eposition; reduces the volume of
runoff to enter a filter strip; assists
the collection of clean or dirty
runoff
Remove sediment buildup
and debris; protect from
animal access; seed as
necessary to maintain
vegetation
Collection facility for
contaminated runoff;
transportation of clean runoff;
off-site treatment of polluted
runoff
Reduce Barnyard
Surface Area
move fencing
Enables runoff containment with
curbing and basins; reduces the
volume of barnyard runoff
Frequent scrapings to reduce
manure buildup; attention to
animal occupancy time
Runoff collection practices;
storage and treatment structure
Roof Barnyard
$5.50/SF
Enables diversion of clean roof
water to prevent contamination;
reduces the amount of barnyard
waste to be treated
Snow removal; monitor for
leakage
Roof runoff management
system; gutters and downspouts
Diversion
$1.58/LF
Protects uncontaminated water
from barnyard contaminants;
reduces volume of contaminated
water runoff
Remove sediment buildup
and debris; seed as necessary
to maintain vegetation; protect
from animal access
Channel to move clean runoff
off-site; collection facility for
contaminated runoff
Grassed
Waterways
$2082.34/AC
Allows transportation of clean or
contaminated water
Seed as necessary to maintain
vegetation; protect from
animal access; remove
sediment buildup and debris
Channel to move clean runoff
off-site; collection facility for
contaminated runoff
Subsurface Tile
Drainage
$1.44/LF
Improves absorption of rainwater
at barnyard surface; helps contain
barnyard pollutants
Check drains for clogging;
monitor transport of polluted
drainage
Collection and treatment of
liquid waste drainage;
collection of undrained runoff
from lot surface
Roof Runoff
Management
System
$4.64/LF
Diverts clean roof water, prevents
contamination; reduces the
amount of barnyard waste to be
treated
Monitor for leakage; snow
removal; remove debris
Collection of diverted clean
water; transportation of clean
roof runoff off-site
Downspout (4"
diam)
$1.41/LF
Enables diversion of clean roof
water to prevent contamination;
enables reduction of barnyard
waste to be treated
Remove debris; monitor for
leakage
Collection of diverted clean
water; transportation of clean
roof runoff off-site
11-27
-------
Table 11-24. Cost data (1993 dollars) for Pennsylvania state averages for manure management practices.
Management
Practice
Cost3 ($)
Benefits
Maintenance
Requirements
Coordinating
Structures/Practices
Curbing (concrete)
$7.37/LF
Provides containment of barnyard
wastes; enables collection of all
effluent and solids
Monitor to ensure working
order
Collection of solid and liquid
waste; transportation of waste
to storage and treatment
Barnyard Paving
(concrete)
$106.37/CY
Enables better cleaning of
barnyard surface; improved herd
health due to cleaner animals
Frequent scrapings to reduce
manure buildup; check
surface and repair damages
Runoff collection practices;
storage and treatment structure
Waste Storage
Pond (10-20,000
cu.ft.)
$3.17/CF
Provides containment and storage
of barnyard wastes; waste may be
removed as needed for spreading
Removal of solids for
spreading or composting;
transportation of fluids for
treatment
Fluid waste treatment facility;
composting facility; transport
system of waste to the storage
pond
Vegetative Filter
Strip
$295/AC
Provides an effective way to treat
fluid portion of waste
Seed as necessary to maintain
vegetation; ensure level soil
surface to prevent
channelling; harvest grass to
remove nutrients from site
Sediment basin to separate
solids prior to strip treatment
Sediment
Detention Basin
$217.92/LF
Allows waste water recycling;
enables use of filter strips for
treatment of liquid
Removal of sediment;
maintain outflow of fluids
onto treatment areas
Treatment of polluted fluid
runoff; treatment or use of
sediment
Ag. Waste
Stacking &
Handling Pad
N/A
Compost may be sold; provides a
means of separating solids for
treatment or use; provides an
effective way to separate and treat
fluid waste
Maintain filter strip; maintain
level pad surface-fill as
needed; prevent spillage of
solids from pad onto filter;
maintain even flow across
interface to filter
Filter strip or storage pond;
compost storage area; transport
of waste to pad site
Composting
N/A
Compost may be sold; compost
serves as an excellent soil
conditioner
Turn windrow stacks to
maintain aeration; check
temperature to ensure
working condition
Compost storage area;
treansport of waste to compost
site
Maintain Riparian
Wetlands:
Tree Plantation
$142.24/AC
Improves population of insect pest
predators; treatment of surface
and subsurface runoff waters;
improves biodiversity on property
Intermittant harvesting to
maximize productivity
Upslope separation and
removal of solids
Streambank
Protection
$21.25/LF
a LF=Linear Foot, SF=Square Foot, CF=Cubic Foot, AC=Acre, CY=Cubic Yard
Source: Evans and Sandman, 1997. Barnyard Runoff Management: An Information Source for Dairy Farmers.
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