CBP/TRS 49/90
September 1990
Estimation of Nonpoint
Source Loading Factors
in the Chesapeake Bay
Watershed Model
^^^^
Chesapeake
Bay
Program
-------
Estimation of Nonpoint Source Loading
Factors in the Chesapeake Bay Model
Linda L Blalock, Graduate Student
Dr. Michael D. Smolen, Extension Specialist
Water Quality Group
North Carolina State University
Grant Number 87-EXCA-3-0829
NATIONAL WATER QUALITY EVALUATION PROJECT
Biological and Agricultural Engineering Department
North Carolina State University
Raleigh, North Carolina
In Cooperation With:
U.S. Department of Agriculture
U.S. Environmental Protection Agency
June 1990
Printed by the U.S. Environmental Protection Agency for the Chesapeake Bay Program
-------
Final Report
Estimation of Nonpoint Source Loading
Factors in the Chesapeake Bay Model
Linda L. Blalock, Graduate Student
Dr. Michael D. Smolen, Extension Specialist
Water Quality Group
North Carolina State University
Introduction
Attention focused on water quality problems in the Chesapeake Bay has
revealed that agricultural activities are in large part responsible for the
degradation of water quality and associated animal and plant life. The
objective of the project entered into by the US Environmental Protection
Agency (US EPA) and North Carolina State University (NCSU) was to assist the
Chesapeake Bay Program in developing appropriate parameters to calibrate the
model US EPA has selected to simulate physical processes in the bay watershed,
namely Hydrological Simulation Program--Fortran (HSPF). HSPF will be used to
evaluate nonpoint source pollution control methods for improving water quality
in the Chesapeake Bay. There are, however, two significant drawbacks to the
use of HSPF. One is that many of the parameters are empirical in nature and
require calibration to determine their value and second is the need of a long
period of hydrological data to calibrate these parameters which is either hard
to obtain or nonexistent.
The model we selected to develop these parameters is CREAMS (A Field
Scale Model for Chemicals, Runoff, and Erosion from Agricultural Management
Systems). CREAMS (Knisel et al, 1980) is a physically based, daily simulation
model used to estimate runoff, erosion, plant nutrient and pesticide yield
from field-sized areas. We used a hypothetical, prototype watershed with
soils and characteristics similar to those that would be encountered in the
Chesapeake Bay watershed. Sediment yield and nutrient loading rates obtained
from CREAMS simulation runs will be the basis for calibrating HSPF.
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CREAMS MODEL
Hydrology Submodel
The hydrology submodel accounts for infiltration, soil water movement,
and soil/plant evapotranspiration between storms and maintains a continuous
water balance. The SCS curve number equation is used to predict surface
runoff:
(P - 0.2s)2
Q =
P + 0.8s
where Q - daily runoff, inches
P = daily rainfall, inches
s - retention parameter, inches
A depth-weighted retention parameter is used to compute the effect of
antecedent moisture, soil conditions, land use, and conservation practices on
runoff and is related to soil water content by:
s - s,max
where s.max - maximum retention parameter in inches
Wi •= weighting factor (function of depth
of each of seven layers and effective
rooting depth of crop)
SM - soil water content in the root zone
in inches
UL - upper limit of soil water storage in
the root zone in inches
s.max is estimated using the CNI moisture condition and the following SCS
equation:
1000
s ,max •» 10
CNI
CNI is for low runoff potential with soil having low antecedent
moisture suitable for cultivation and is related to CNII by the following
polynomial:
CNI - -16.91 + 1.348CNII - .01279CNII2 + .0001171CNII3
CNII selection is outlined in Appendix 1. However, the same results are
obtained as appear in Table A-4 in the CREAMS PC manual (Rawls, et al, 1980)
saving one the trouble of calculating each curve number.
Potential evapotranspiration (ET) is computed using daily temperature
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and daily solar radiation. Soil evaporation and plant transpiration are
computed separately; both use potential ET and the leaf area index. The leaf
area index is defined as the area of all leaves and stem within one square
meter. The submodel uses a soil storage routing technique to predict flow
through the root zone when accounting for percolation. The root zone is
divided into seven layers or storages for routing purposes. An appropriate
rooting depth for the crop on the field is selected by the user and the total
soil water storage for each of the seven layers is determined based on soil
properties.
Erosion Submodel
CREAMS is capable of representing sediment yield from a field with
overland flow, channel flow, and/or impoundments. The user selects the most
descriptive combination. In the erosion submodel, detachment on interrill and
rill areas and transport and deposition by rill flow are the erosion-transport
processes in the overland flow option. Detachment is described using slope,
slope length, and K, C, and P factors from the Universal Soil Loss Equation
(USLE), K being the soil erodibility factor, C the soil loss ratio, and P the
contouring factor. Runoff volume, peak runoff rate, and storm erosivity (El)
are also needed in the detachment equations and are computed in the hydrology
submodel and passed to the erosion submodel. The Yalin equation is used to
calculate sediment transport capacity. The submodel computes an initial
potential sediment load (up-slope segment sediment load + lateral inflow
sediment load). If this potential load is less than the transport capacity,
detachment occurs; if the potential load is greater than transport capacity,
then deposition occurs. Separate equations are used for determining soil
detachment and sediment transport.
An enrichment ratio (ER) is computed in the erosion submodel using
specific surface areas for sand, silt, clay, and organic matter. This value
represents the total specific surface area for the sediment yield to that of
the original soil. An runoff velocity decreases, larger soil particles drop
out of suspension and are deposited on the field. Finer particles settle out
more slowly by remaining in suspension longer and are transported to the edge
of the field. Clay particles with their high surface area-to-volume ratio are
noted for this type of behavior and enrichment. Therefore, high enrichment
ratios indicate that primarily clays are in the runoff and that the
implementation of good land conservation management practices have reduced the
amount of sediment leaving the field by limiting the size of the soil
particles leaving the field to small fines. Conversely, low enrichment ratios
indicate that sediment yield is being controlled by detachment and that larger
soil particles are leaving the field.
Nutrient Submodel
The. nutrient submodel in CREAMS simulates nitrogen and phosphorus
processes in and losses from the field. Nitrogen processes include nitrogen
in runoff and sediment, mineralization, plant uptake, leaching,
denitrification, fertilizer application, and rainfall nitrogen. Phosphorus
processes are field applications and losses in sediment and runoff. The
loading rate of nitrogen and phosphorus transported by sediment (SED_) is
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predicted by the following equations:
SED_ - SOIL_ * SED * ER_ , and
ER_ - A- * SEDB_
where SOIL_ - N or P content (kg/kg soil) in the field
SED - sediment predicted by the erosion model, kg/ha
ER_ - enrichment ration of N or P
A_ - coefficient for N or P
B_ - exponent for N or P
Conservation practices (best management practices) are commonly used
to reduce runoff and soil erosion from fields in the hopes of maintaining the
field's maximum production capability in a cost-effective manner. In so
doing, a fringe benefit is realized in that fertilizer nutrients are retained
on the field available for plants to take up and subsequently, the amount
which leaves the field and enters rivers, streams and other water bodies is
reduced. [Whether these practices are effective in improving water quality is
still a question for discussion.] Therefore, we decided to compare the
effects of conventional and conservational tillage practices on runoff and
sediment, nitrogen and phosphorus yields from the field. Loading rates for
sediment, nitrogen, and phosphorus generated by CREAMS can be used to more
accurately estimate the potency factor parameter [ratio of constituent yield
to sediment (washoff or scour) outflow] used in the HSPF watershed model.
HSPF POTENCY FACTORS
The HSPF subroutine QUALSD simulates the removal of a quality
constituent from a pervious land surface by association with the sediment
removal determined in module section SEDMNT. This approach assumes that the
particular quality constituent removed from the land surface is proportional
to the sediment removal. The relation is specified with user-input potency
factors. Potency factors, then, indicate the constituent strength relative to
the sediment removed from the surface. For each quality constituent
associated with sediment, the user supplies separate potency factors for
association with washed off and scoured sediment. The basic equation for
removal of sediment-associated constituents by sediment detached in washoff is
simulated by:
WASHQS - WSSD*POTFW
where:
WASHQS - flux of quality constituent associated with
. detached sediment washoff in quantity/acre per
interval
WSSD = washoff of detached sediment in tons/acre per
interval
POTFW = washoff potency factor in quantity/ton
And the removal of constituents by scouring of the soil matrix is simulated
by:
-------
SCRQS •= SCRSD*POTFS
where:
SCRQS - flux of quality constituent associated with scouring of the
matrix soil in quantity/acre per interval
SCRSD - scour of matrix soil in tons/acre per interval
POTFS - scour potency factor in quantity/ton
SOILS AND FARMING PRACTICES
We simulated runoff, sediment, nitrogen and phosphorus yields from a
35-acre watershed planted in continuous corn. We selected five (5) soil types
to represent soils characteristic of the major regions in the bay
watershed--Galestown (Psammentic Hapludult, Sandy), Norfolk (Typic Paleudult,
Fine-Loamy), two types of Cecil (Typic Hapludult, Clayey), and Penn Loam
(Table 1). For our hypothetical field, we represented sediment yield from the
field using the overland flow option. The slope of our field ranged from 2 to
10 percent depending on soil type. In all cases, slope length was 120 feet
and a simple, uniform slope profile was used. We chose a length-to-width
ration of 3.8 based on a hydrologic map obtained from the Chesapeake Bay
Liaison Office (CBLO). We broadcast a 10-5-5 fertilizer in April 14 at the
rate of 150 Ib N/acre. We selected the daily rainfall option using 1974-78
rainfall data also obtained from the CBLO. Total annual precipitation for the
5-year period ranged from 39 to 53 inches (Appendix 2). We also used actual
bay area average monthly temperatures and solar radiation values for the five
(5) years, also obtained from the CBLO. The farming activities we selected
for our hypothetical field include chisel plowing on April 15, disking on
April 16, planting on April 20, and harvesting on October 1.
Table 1. SOILS USED IN SIMULATION
Soil 1 Galestown, loamy sand (not typically found on 8% or 10% slopes)
Soil 2 Norfolk, loamy sand, loamy fine sand, sandy loam
Soil 3 Cecil, sandy loam, sandy clay loam, clay loam, clay
Soil 4 Cecil, sandy clay loam, clay loam, clay
Soil 5 Cecil, sandy clay loam, clay loam, clay -- eroded phase (not
typically found on 2% slope)
Soil 6 , Penn Loam, loam, silt loam
See Appendix 1 for soil profile descriptions.
We designed two scenarios to compare the difference that selected
management practices made in runoff and sediment, nitrogen, and phosphorus
yields. The base, or reference, scenario we defined as a field under
conventional tillage with up-and-down slope plowing with less than 30 percent
crop residue at time of planting. The alternate scenario was defined as a
field under conservation tillage with contour chisel plowing with more than 30
percent crop residue at time of planting. We defined conventional tillage as
a tillage operation which would leave less than 30 percent crop residue at
time of planting. We obtained soil profiles and characteristics from
appropriate Soils 5 sheets and the CREAMS manual (Appendix 3).
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RESULTS OF CREAMS SIMULATONS
As expected, runoff was reduced from the field when the alternative
management practices were employed (Table 2) . Reduction ranged from 21-44
percent, depending on soil type. What we did not expect was the small amount
of runoff. Several inches per year were expected but instead, runoff averaged
from less and one (1) inch to about 1.5 inches over the 5-year period. A
sensitivity analysis. of the hydrology submodel parameters revealed that the
most influential parameter in generating runoff is the SCS curve number which
influences the retention parameter; i.e., the maximum potential difference
between rainfall and runoff at the start of the storm. The larger the curve
number, the smaller the retention parameter and the more runoff you get and
vice versa. We used curve numbers from Table A-4 in the CREAMS PC manual
(USDA SCS TR 71) for appropriate soil-cover situations and these curve number
just did not generate the runoff experience told us we should expect (Refer to
Hydrology Submodel section above for description of how runoff is predicted.).
Because we knew that the driving parameter in the runoff equation was the
curve number, we decided to increase the curve number on the Soil 5 scenario
just to see what would happen (Table 2). An increase in runoff did occur
(from 1.5 to 2.7 inches), but because there was no justification for using the
larger values; i.e., no actual data, we continued to use the recommended
values from Table A-4.
Table 2. RUNOFF AS A FUNCTION OF SOIL TYPE (1974-78)
Annual Average Precipitation - 44.4 inches)
BASE ALTERNATE
SCENARIO1 SCENARIO2
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
13
2
3
4
5
6
1
1
2
3
.072
.806
.130
.530
.688
.068
• m
(67)4
(78)
(78)
(78)
(83)
(85)
.040
.592
.858
1.206
2.154
2.171
(65)
(76)
(76)
(76)
(81)
(82)
% REDUCTION
44
26
24
21
19
29
.0
.5
.0
.0
.9
.2
•"•Conventional tillage with up-and-down slope plowing, residue less than 30
percent.
^Conservation tillage with residue greater than 30 percent.
1: Galestown, loamy sand (Hydrologic Group A, not typically found on 8%
or 10% slopes)
Norfolk, loamy sand, loamy fine sand, sandy loam (Hydrologic Group B)
Cecil, sandy loam, sandy clay loam, clay loam, clay (Hydrologic
Group B)
Cecil, sandy clay loam, clay loam, clay (Hydrologic Group B)
Cecil, sandy clay loam, clay loam, clay -- eroded phase (not
typically found on 2% slope)
Soil 6: Penn Loam, loam, silt loam (Hydrologic Group C)
^Curve number for antecedent rainfall condition II in parentheses ( ) .
Soil 2:
Soil 3:
Soil 4:
Soil 5:
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Because runoff was low, sediment yields from the field were also low
and less than expected. Values ranged from 0 to 2.6 tons/acre (Table 3, Soil
5 with higher curve number not included in range given here). The results,
however, do reflect a reduction in sediment yield when conservation tillage
with contour plowing is implemented, with values ranging from about 47 to
almost 67 percent, depending on the soil type and the slope of the field.
Table 3. SEDIMENT YIELD AS A FUNCTION OF SOIL TYPE, SLOPE, AND TILLAGE
PRACTICE (1974-78 averages, Annual Average Precipatation - 44.4 inches)
2% slope
Base3
Alt.4
% red.
4% slope
Base
Alt.
% red.
6% slope
Base
Alt.
% red.
8% slope
Base
Alt.
% red.
10% slope
Base
Alt.
% red.
SOIL I1
(67/65)2
SOIL 2 SOIL 3 SOIL 4
(78/76) (78/76) (78/76)
SOIL 5
(83/81)
SOIL 6
(85/82)
0
0
0
.006
.002
66.7
.018
.006
66.7
.028
.012
57.0
.108
.042
61.1
.200
.078
61.0
.336
.142
57.7
.528
.234
55.7
.066
.030
54.5
.240
.106
55.8
.484
.232
52.1
.798
.404
49.4
1.208
.596
50.7
.090
.042
53.3
.314
.144
54.1
.632
.336
46.8
1.130
.558
50.6
1.736
.800
53.9
.554
.260
53.1
1.214
.542
55.4
2.05
.89
56.6
3.05
1.326
56.5
.208
.086
58.7
.714
.312
56.3
1.542
.674
56.3
2.644
1.122
57.6
•"•Soil 1: Galestown, loamy sand (not typically found on 8% or 10% slope); Soil
2: Norfolk, loamy sand, looam fine sand, sandy loam; Soil 3: Cecil, sandy
loam, sandy clay loam, clay loa m, clay; Soil 4: Cecil, sandy clay loam, clay
loam, clay; Soil 5: Cecil, sandy clay loam, clay loam, clay -- eroded phase
(not typically found on 10% slope); Soil 6: Penn Loam, loam, silt loam
2Curve numbers for antecedent rainfall condition II base and alternate
scenarios.
•^Conventional tillage with up-and-down slope plowing, residue less than 30%.
^Conservation tillage with residue greater than 30%.
Enrichment ratios (ER) for the six soils are shown in Table 4. As
expected, ERs decreased as sediment yield increased, indicating detachment and
transport of large soil particles along with fines and organic matter. The
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extremely high ER values for Soils 1 and 2 at low slopes indicate that runoff
was low and, consequently, the sediment yield was zero or very near zero. A
couple of observations can be made from these data. First, because sediment
yield was either zero or very near zero, nutrient losses computed in the
nutrient submodel, if any, will be known to exist in runoff and not in
erosion. Therefore, to aid in reducing nutrient losses, it is important to
control runoff first. In so doing, not only are runoff and accompanying
nutrients reduced, but because erosion is driven by runoff, erosion is
controlled as well. .Second, note that when conservation practices are
employed, ER values are generally higher. The exceptions in these runs, we
think, are due to the questionable results obtained by using the recommended
curve numbers from Table A-4 in the CREAMS PC manual (USDA SCS TR 72).
Table 4. AVERAGE ANNUAL ENRICHMENT RATIOS (1974-78)
Annual Average Precipitation - 44.4 inches
2%
4%
6%
8%
10%
Soil 1
Base1
Alt.2
Soil 2
Base
Alt.
Soil 3
Base
Alt.
Soil 4
Base
Alt.
11.339
11.373
6.256
6.268
3.515
3.494
2.783
2.743
8.516
9.183
4.374
4.351
2.567
2.618
2.153
2.188
6.809
7.322
4.025
4.168
2
2
174
102
1.888
1.781
3.441
3.446
1.922
1.865
1.663
1.654
2.884
2.863
1.759
1.751
1.549
1.562
Soil 5
Base
Alt.
Soil 6
Base
Alt.
2.278
2.263
1.956
1.947
1.751
1.754
1.653
1.674
1.493
1.512
1.464
1.476
1.360
1.369
1.345
1.343
•"•Soil 1: Gales town, loamy sand (not typically found on 8% or 10% slopes)
Soil 2: Norfolk, loamy sand, loamy fine sand, sandy loam
Soil 3: Cecil, sandy loam, sandy clay loam, clay loam, clay
Soil 4: Cecil, sandy clay loam, clay loam, clay
Soil 5: Cecil, sandy clay loam, clay loam, clay -- eroded phase (not
typically found on 2% slope)
Soil 6: Penn loam, loam, silt loam
^Conventional tillage with up-and-down slope plowing, residue less than 30%,
^Conservation tillage with residue greater than 30%.
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Soil type, field slope, and management practice also affected the
amount of total nitrogen and total phosphorus leaving the field (Tables 5 and
6). Total nitrogen and total phosphorus include runoff- and sediment-
associated constituents. Average annual losses ranged from
0.04 - 5.6 kg/ha for nitrogen and 0.006 - 1.6 kg/ha for phosphorus. The use
of conservation tillage and contour plowing reduced the loading rate by 28 -
59 percent for nitrogen and 33 - 70 percent for phosphorus. Notice that there
are some nutrient losses on Soil 1 at 2, 4, and 6 percent slopes. Recalling
that there was little to no sediment yield on this soil at these slopes, it is
our conclusion that nitrogen and phosphorus losses occurred primarily in
runoff rather than erosion. Hence, it is important to implement first those
conservation practices that will reduce runoff from the field.
A complete set of output results appears in Appendix 4.
HSPF washoff potency factors were calculated by dividing the sediment
loss from the field for associated nitrogen and phosphorus by the total
sediment yield (Table 7). Most of the alternate scenario values are larger
than the base scenario values because the fines associated with reduced runoff
are usually smaller than soil particles associated with runoff without
conservation practices and therefore have a higher adsorption capacity. We
did not calculate potency factors for soil matrix scouring.
NITROGEN LEACHING STUDY
We also used CREAMS to examine nitrogen leaching by simulating
fertilizer application at different nitrogen rates. We used the same
commercial 10-5-5 fertilizer broadcast at rates ranging from 50-350 Ib
N/acres. The base scenario (conventional tillage with up-and-down slope
plowing) was used on Soil 4 (eroded Cecil) with the 35-acre field in
continuous corn at 10 percent slope for the 5-year (1974-78) simulation
period. Potential nitrogen uptake was related to the potential yield in
bushels.
Results of the study on nitrogen leaching reduction as a function of
fertilizer application rate and potential corn yield indicate that there is a
maximum uptake rate of nitrogen after which the uptake rate levels out (Table
7). Reductions ranged from 26 to 64 percent (Fig. 1; negative values indicate
a nitrogen deficit). However, it is important to bear in mind that although
reduction of leached nitrogen was greater than 50 percent in most simulations,
these data must be understood in light of all the data--
rates of uptake, leaching, and excess nitrogen. The model assumes that all
nitrogen in excess of plant requirement is
available to leach. Hence, these data indicate that the plant can take up a
given amount of nitrogen after which the excess, no longer available to
plants, is leached below the root zone. In these simulations, the amount of
leached nitrogen ranged from 5 to 227 kg/ha. So the fact that part
of the data suggest significant reductions, the remainder of the data indicate
that the plants were unable to take up the excess and that the excess was then
available to migrate down to the groundwater, eventually entering streams and
tributaries which empty into the Chesapeake Bay. We caution the interpreter
of similar simulations to make decisions based on all of the data and not just
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selected portions.
Table 5. NITROGEN (N) LOSS AS A FUNCTION OF SOIL TYPE, SLOPE, AND TILLAGE
PRACTICE (1974-78 averages, Annual Average Precipitaton - 44.4 inches)
SOIL 1A
2% slope
Base5 .073
Alt.3 .040
% red. 45.1
4% slope
Base .097
Alt. .040
% red. 58.9
6% slope
Base .138
Alt. .064
% red. 53.5
8% slope
Base
Alt.
% red.
10% slope
Base
Alt.
% red.
SOIL 2
.950
.645
32.2
1.206
.766
36.5
1.456
.911
37.5
1.834
1.089
40.6
2.240
1.315
41.3
SOIL 3
1.534
1.065
30.6
2.015
1.312
34.9
2.600
1.663
36.0
3.277
2.094
36.1
4.061
2.510
38.1
SOIL 4
Kg/na- -
2.129
1.537
27.8
2.745
1.884
31.4
3.501
2.408
31.2
4.512
2.918
35.3
5.608
3.458
38.3
SOIL 5
5.576
3.856
30.8
6.981
4.553
34.8
8.501
5.356
37.0
0.261
6.253
39.1
SOIL 6
5.040
3.077
38.9
6.319
3.756
40.6
8.076
4.638
42.6
10.080
5.640
44.0
•"•Soil 1: Galestown, loamy sand (not typically found on 8% or 10% slopes)
Soil 2: Norfolk, loamy sand, loamy fine sand, sandy loam
Soil 3: Cecil, sandy loam, sandy clay loam, clay loam, clay
Soil 4: Cecil, sandy clay loam, clay loam, clay
Soil 5: Cecil, sandy clay loam, clay loam, clay -- eroded phase (not
typically found on 2% slope)
Soil 6: Penn Loam, loam, silt loam
^Conventional tillage with up-and-down slope plowing, residue less than 30
percent.
^Conservation tillage with residue greater than 30 percent.
10
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SUMMARY AND CONCLUSIONS
The use of conservation tillage and contour plowing reduced the amount
of runoff, sediment yield, nitrogen, and phosphorus leaving the field. Low
runoff values were due to the curve numbers selected. Subsequent low sediment
and nutrient yields reflect insufficient runoff to generate higher losses.
Use of a higher curve number generated more runoff and subsequent higher
sediment and nutrient yields. Additional simulations using actual soils from
the Chesapeake Bay watershed and further investigation of the curve number are
recommended.
Table 6. PHOSPHORUS (P) LOSS AS A FUNCTION OF SOIL TYPE, SLOPE, AND TILLAGE
PRACTICE (1974-78 averages, Annual Average Precipitaton <= 44.4 inches)
SOIL I1SOIL 2
SOIL 3
SOIL 4
SOIL 5
SOIL 6
2% slope
Base^
Alt.3
% red.
4% slope
Base
Alt.
% red.
6% slope
Base
Alt.
% red.
8% slope
Base
Alt.
% red.
10% slope
Base
Alt.
% red.
-kg/h-
.010
.006
44.6
.019
.006
69.9
.034
.015
57.3
.143
.088
38.1
.235
.132
43.8
.410
.162
60.4
.461
.248
46.1
.607
.330
45.7
.235
.152
35.5
.409
.241
41.1
.619
.367
40.7
.863
.522
39.5
1.145
.672
41.3
.320
.214
33.1
.541
.339
37.4
.814
.528
35.1
1.178
.711
39.6
1.582
.906
42.8
1.070
.685
36.0
1.576
.935
40.7
2.123
1.225
42.3
2.756
1.548
43.8
.770
.448
41.8
1.230
.692
43.7
1.863
1.010
45.8
2.584
1.371
46.9
•"•Soil 1: Galestown, loamy sand (not typically found on 8% or 10% slopes)
Soil 2: Norfolk, loamy sand, loamy fine sand, sandy loam
Soil 3: Cecil, sandy loam, sandy clay loam, clay loam, clay
Soil 4: Cecil, sandy clay loam, clay loam, clay
Soil 5: Cecil, sandy clay loam, clay loam, clay -- eroded phase (not
typically found on 2% slope)
Soil 6: Penn Loam, loam, silt loam
^Conventional tillage with up-and-down slope plowing, residue less than 30
percent.
•^Conservation tillage with residue greater than 30 percent.
11
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Table 7: POTENCY FACTORS FOR DETACHED SEDIMENT WASHOFF FOR NITROGEN (N) AND
PHOSPORUS
SOIL I1
N P
2Z slop*
Base*
Alt*
SOIL
N
0.01S
0.024
2
P
0.002
0.003
SOIL 3
N P
0.01 0.002
0.016 0.002
(SOIL 4
N' P
0.01 0.002
0.008 0.002
SOIL 5 SOIL 6
N P N f ,'
0.011 0.002^
0.016 0.002°
4Z slope
Bis* 0.007 0.001 • 0.005 0.001 0.004 0.001 0.004 0.001 0.004 0.001 0.004 0.001
Alt. 0.009 0.001 0.008 0.001 0.005 0.001 0.006 0.001 0.007 0.001 0.005 0.001
6Z slope
Base 0.003 0.001 0.003 0.001 0.002 0.001 0.002 0.001 0.003 0.001 0.002 0.001
Alt. 0.005 0.001 0.005 0.001 0.003 0.001 0.003 0.001 0.004 0.001 0.003 0.001
8Z slope
Base 0.002 0.001 0.002 0.0005 0.002 0.0005 0.002 0.0005 O.C02 0.0004
Alt. 0.003 0.001 0.002 0.001 0.002 0.0006 0.003 0.0006 O.C02 O.CC05
10: slope
Base 0.002 0.001 0.001 0.0004 0.001 0.0004 0.002 0.0004
Alt. 0.002 0.001 0.002 0.0005 0.002 0.0005 0.002 C.0005
•"•Soil 1: Galestown, loamy sand (not typically touna on o% or 1U% slopes;
Soil 2: Norfolk, loamy sand, loamy fine sand, sandy loam
Soil 3: Cecil, sandy loam, sandy clay loam, clay loam, clay
Soil 4: Cecil, sandy clay loam, clay loam, clay
Soil 5: Cecil, sandy clay loam, clay loam, clay -- eroded phase (not
typically found on 2% slope)
Soil 6: Penn Loam, loam, silt loam
^Conventional tillage with up-and-down slope plowing, residue less than 30
percent.
•^Conservation tillage with residue greater than 30 percent, .pa
12
-------
Table 8. REDUCTION OF NITROGEN LEACHING AS A FUNCTION OF FERTILIZER
APPLICATION RATE (1974-78 averages, Ann. Ave. Precipitation - 44.4 inches)1
Ib N/ac
applied
N
uptake
N N Efficiency of
leached excess Fertilizer Reduction^
Potential Nitrogen Uptake - 150 kg/ha (134 Ib/ac)
Potential Corn Yield = 85 bushels
- .............. kg/ha ............
50 123 57 -73
150 123 120 27
200 123 152 77
250 123 215 127
300 123 215 177
350 123 247 227
%
63
64
62
64
64
Potential Nitrogen Uptake •= 225 kg/ha (200 Ib/ac)
Potential Corn Yield - 128 bushels
50
150
200
250
300
350
148
184
184
184
184
184
41
86
118
149
181
213
-98
-34
16
66
116
166
45
64
62
64
64
Potential Nitrogen Uptake - 300 kg/ha (268 Ib/ac)
Potential Corn Yield = 170 bushels
50
150
200
250
300
350
154
220
238
245
246
248
37
63
86
116
147
179
-104
- 70
- 38
5
54
102
26
46
60
62
64
^-Simulations done on Soil 4 (Cecil, sandy clay loam, clay loam, clay) planted
in continuous corn at 10 percent slope.
2 Percentage of application increment that is leached.
REFERENCES
Knisel, W. G. (Ed.). CREAMS: A field-scale model for Chemicals, Runoff, and
Erosion from Agricultural Management Systems. U.S. Department of Agriculture,
Conservation Research Report No. 26, 643 pp.
Rawls, W. J., C. A. Onstad, and H. H. Richardson. 1980. Residue and tillage
effects on SCS runoff curve numbers. In: Knisel, W. G. (Ed.). CREAMS: A
field-scale model for Chemicals, Runoff, and Erosion from Agricultural
Management Systems. U.S. Department of Agriculture, Conservation Research
Report No. 26, Vol. Ill, pp. 405-425.
13
-------
APPENDIX 1
-------
CCNSERVAIICN TILLAGE Ebl'ELIS CN CURVE NUMBER
Watershed in good hydrologic condition with soils in hydrologic group
A and B and is farmed in straight row, continuous corn. Planned tillage
operations are chisel plowing and heavy disking before planting com.
Hvdrologic Group A
Step 1. Determine curve number without conservation tillage.
CN = 67 (Table 1)
Step 2. Determine residue amount left on surface.
Corn residue = 4500 Ib/ac (Jim Haimawald, CBLO)
Reduction as a result of tillage operations (Table 2)
(4500 lb/ac)(0.65 chisel plow)(0.30 heavy disk) = 877.5 l±>/ac
Corn residue remaining = 880 Ib/ac
Step 3. Reduce curve number (Table 3).
Corn is a large residue crop; interpolation give a
CN reduction = 3%
Step 4. Adjust curve number for conservation tillage.
CN = (CN from Step 1)(1 - CN reduction %/100)
CN = (67)(1 - 3/100) = 64.99
CN = 65
Hvdrolocric Group B
Step 1. Determine curve number without conservation tillage.
CN = 78 (Table 1)
Step 2-3. Same as above.
Step 4. Adjust curve number for conservation tillage.
CN = (78)(1-3/100) = 75.66
CN = 76
Source: "Procedure To Estimate Effects of Conservation Tillage on Reducing
Direct Runoff Using SCS Curve Number," CREAMS, CRR 26, pp. 420-425.
-------
Table I. RunofT Curve Numbers for Hydrologic Soil-Cover Complexes for Ante-
cedent Rainfall Condition II. and /„ - 0.2S
Land Use
or Cover
Fallow
Row crops
Small grain
Close-seeded
legumes or
rotation
meadow
Pasture or
range
Meadow
(permanent)
Woods
(farm wood-
lots)
Farmsteads
Roads and
right-of-way
(hard surface)
Treatment
or Practice
Straight row
Straight row
Straight row
Contoured
Contoured
Terraced
Terraced
Straight row
Straight row
Contoured
Contoured
Terraced
Terraced
Straight row
Straight row
Contoured
Contoured
Terraced
Terraced •
Contoured
Contoured
Contoured
*
HyJrolnyic
Condition
__
Poor
Good
Poor
Good
Poor
Good
Poor
Good
Poor
Good
Poor
Good
Poor
Good
Poor
Good
Poor
Good
Poor
Fair
Good
Poor
Fair
Good
Good
Poor
Fair
Good
_
_
'Hytlroloaie
A
77
72
67
70
65
66
62
65
63
63
61
61
59
66
58
64
55
63
51
68
49
39
47
25
6
30
45
36
25
59
74
B
36
81
78
79
75
74
71
76
75
74
73
72
70
77
72
75
69
73
67
79
69
61
67
59
35
58
66
60
55
74
84
Soil Group
c
91
88
85
84
82
80
78
84
83
82
81
79
78
85
81
83
78
80
76
86
79
74
81
75
70
71
77
73
70
82
90
D
94
91
89
88
86
82
81
88
87
85
84
82
81
S9
85
85
83
83
SO
89
84
SO
88
S3
79
78
S3
79
77
86
92
Sourer: U. S. Soil Conservation Service. Nuiionul Engineering Handbook. Hydrology. Section 4
(1972) and U. S. Depl. Agr. ARS 41-172 (1970).
-------
Table 2. Residue remaining
from tillage operations (1)
Tillage
operations
Residue
remaining
plow 6 5
Rod weeder 90
Light disk • 70
Heavy disk 30
Moldboard plow 10
Till plant 80
Fluted coulter 90
V Sweep 90
(1) Crop residue remaining
= (crop residue from
table 1) x ( tillage
factor (s)).
Table 3. Reduction in runoff curve numbers
caused by conservation tillage and
management
Large
residue
crop(l)
(lb/acre)
0
400
700
1,100
1,500
2,000
2,500
6,200
Medium
residue
crop(2)
(Ib/acre)
0
150
300
450
700
950
1,200
3,500
Surface
covered
by residue
(%)
0
10
19
28
37
46
55
90
Reduction
in curve
number(3)
(%)
0
0
2
4
6
8
10
10
(1) Large-residue crop (corn)
(2) Medium residue crop (wheat, oats,
barley, rye, sorghum, soybeans).
(3) Percent reduction in curve number
can be interpolated linearly. Only
apply 1 to 1/2 of these percent
reductions to CN's for contouring and
terracing practices when they are used
in conjunction with conservation
tillage.
PROCEDURE TO ESTEyftTE EFFECTS OF CONSERVATICN TILLAGE ON REDUCING DIRECT
RUNOFF USING THE SCS CURVE NUMBER
Conservation tillage is a form of noninversion tillage that retains
protective amounts of residue mulch on the surface throughout the year.
Conservation tillage practices include fill planting, chisel planting, strip
tillage, sweep tillage, chop planting, and no-till. Of these, only no-till
has not reduced direct runoff consistently when applied year after year on
experimental plots and watersheds. Direct runoff and associated peak
discharges are reduced by crop residue cover, which increases infiltration
potential through 1) lessening rainfall impact and surface crusting, 2)
decreasing runoff velocity by lengthening flow paths and increasing surface
roughness, 3) creating additional surface storage, and 4) providing organic
matter to improve soil structure.
Direct runoff is computed using thee SCS runoff curve number technique,
as described in chapters 9 and 10 of the National Engineering Handbook,
Section 4, Hydrology. The selected runoff curve number can be reduced by a
percentage to account for the effects of conservation tillage and residue
management practices. To take advantage of this reduction, conservation
tillage and residue management must be continued for the expected life of
the engineering practice. The adaptability of the tillage practices to the
local soil and crop growth conditions should be checked. This includes
drainage limitations of the soils, pest control problems, equipment on hand,
and the attitude and abilities of the farmers. No reductions should be used
-------
with continuous no-till or similar practices that do not increase
infiltration significantly.
Estimating the amount and type of residue cover remaining after harvest
is necessary for this procedure. Assumptions incorporated into the
procedure are, 1) normal decomposition of residue over the dormant season
and 2) no carryover of residue from year to year.
The approximate amount of residue can be determined by:
1. F.crH mating residue for 190^1 conditions bv experienced personnel.
The SCS State resource conservationist or agronomist can estimate the
percentage of the surface presently covered by residue or the amount of
residue resulting from specific crops and tillage practices.
2) Estimating residue cover by sampling airmg a transect.
One technique is to use a cord, 50 ft. or longer, that has 100 equally
spaced knots or other readily visible markings. This cord is stretched
diagonally across several rows, and the knots that contact a piece of mulch
are counted. Each knot represents 1% of the sample. This procedure is
repeated at randomly selected locations on the field, and the data are
averaged to obtain a representative percentage of surface area covered by
residue for the field.
3) Estimating residue from empirical data developed from crop and tillage
operation records.
a. Estimate the residue produced by the crop in pounds per acre from the
estimated crop yield using the equation and data given in Table 4.
b. Compute the amount of residue that will remain on the surface by using
the types of tillage practice and remaining residue from Table 5.
The type of residue is classified according to the maximum amount of
residue the crop will produce. Medium residue crop will produce residue
amounts up to about 4,000 Ib per acre and include wheat, oats, barley, rye,
sorghum, and soybeans. A large-residue crop, such as corn, can produce from
about 4,000 to 8,000 Ib per acre of residue.
The computations of direct runoff from areas using conservation tillage
and residue management practices involves five steps:
1. Determine the curve number (CN) for the hydrologic soil group, land
use, and treatment given in the National Engineering Handbook, Section 4,
(Table 1, this section).
2. Estimate the percentage of the surface covered by crop residue or the
amount (Ib per acre) of crop residues to be left on the surface. An
of the three preceding methods can be used.
3. Determine the percentage reduction in runoff curve number caused by
conservation tillage practices from Table 6.
-------
4. Determine the adjusted CN by reducing the CN obtained in step 1 by the
percentage obtained in step 3.
5. Obtain the direct runoff from the given rainfall using the curve
number obtained in step 4, according to the procedure in the National
Qigineering Handbook, Section 4, (figure 10.1). The adjusted CN also can
be used to determine the associated peak discharge.
Table 4—Method for converting
crop yields to residue(l)
Crop Straw/grain Bushel
ratio weight
Table 5—Residue remaining from
tillage operations(l)
Tillage
operation
Residue
remaining
POL J.cy
VJJLJ1
uats
iA.
m-| i i -ril -vrYt-
/U
->fl
JU
i n
an
Fluted coulter-
V Sweep-
-90
(1) Crop residue = (straw/
grain ratio) x (bushel weight
in ib/bu) x ( crop yield in
bu/acre).
(1) Crop residue remaining =
(crop residue from table 1) x
(tillage factor (s)).
Table 6—Reduction in runoff curve numbers cause by
conservation tillage and residue management.
Large residue Medium residue
crept1) crop(2)
Surface covered
by residue
Reduction in
number(3)
(Ib/acre)
0
400
700
1,100
1,500
2,000
2,500
6,200
(Ib/acre)
0
150
300
450
700
950
1,200
3,500
(%)
0
10
19
28
37
46
55
90
(%)
0
0
2
4
6
8
10
10
(1) Large-residue crop (corn).
(2) Medium residue crop (wheat, oats, barley, rye, sorghum, and
soybeans).
(3) Percent reduction in curve numbers can be interpolated linearly.
Only apply 0 to 1/2 of these percent reductions to CN's for
contouring and terracing practices when they are used in
conjunction with conservation tillage.
-------
When conservation tillage and residue management are used in conjunction
with contouring or with contouring and terracing, 0 to one-half of the table
3 reduction is needed, based on the type of soil and the increased potential
for infiltration, The smaller reduction is applied to the CN for contouring
or contouring and terracing. Research data are unavailable to determine the
combined effects of residue and these conservation practices to reduce
runoff.
Example 1;
A cultivated area in poor hydrologic condition with soils in hydrologic
soil group C is fanned in straight-row continuous corn. Corn yields are 90
bu per acre. Conservation tillage operations are estimated to provide a 50%
surface coverage with corn residue. Determine the direct runoff from a 3.0"
rainfall in 24-hr.
Step 1. Determine curve number without conservation tillage.
For straight-row, continuous corn, in poor hydrologic condition, in
a "C" soil; C = 88 (Table 1).
Step 2. Determine residue amounts left on surface.
The estimate of surface covered by corn residue was given directly
as 50%.
Step 3. Reduce curve number.
Entering Table 6 with 50% surface cover; CN reduction = 9%.
Step 4. Adjust curve number for conservation tillage.
CN = (CN from step 1) x (1-(CN reduction %/100)).
CN = 88 (l-(9/100))
CN = 80.1, use 80.
Step 5. Determine direct runoff, in inches, with conservation tillage.
With 3.0" rainfall and CN = 80; runoff = 1.3"(NEH, Sec.4, Table
10.1).
Example 2;
The watershed above a proposed engineering practice is a good hydrologic
condition with soils in hydrologic group B and is farmed in a straight-row
corn-soybean rotation. Com yields are expected to average 100 bu per acre
and soybean yields 40 bu per acre. The only tillage operations planned are
chisel plowing and heavy disking before planting soybeans and heavy disking
only before corn planting. The farmer is committed to these conservation
tillage practices, which are suitable for the local conditions. Assume 50%
of the cultivated area is in corn and 50% in soybeans in any one year.
Determine the direct runoff from a 3.0" rainfall in 24-hr as follows:
Step 1 Determine curve number without conservation tillage.
For corn: CN = 78 (table 1).
For soybeans: CN = 78 (table 1).
-------
Step 2 Residue amounts left on surface,
(a) After harvest (from Table 4):
Crop residue = (straw/grain ratio x bushel weight x crop yield).
Corn residue = (1.0 x 56 Ib/bu x 100 bu/ac) = 5,600 Ib/acre.
Soybean, residue = (1.5 x 60 Ib/bu x 40 bu/ac) = 3,600 Ib/acre).
(b) Reduction in crop residue as a result of tillage operations,
(from Table 5).
Corn residue remaining = (5,600 Ib/ac x 0.65 chisel plow x heavy
disk) = 1090 Ib/acre.
Soybean residue remaining = (3,600 Ib/ac x 0.30 heavy disk)
= 1,080 Ib/acre.
Step 3 Reduce curve number (from Table 6).
(a) Soybeans following corn, with corn residue = 1,090 Ib/acre since
corn is a large-residue crop; CN reduction = 4%.
(b) Corn following soybeans, with soybean residue = 1,080 Ib/acre
since soybean is a medium-residue crop; CN reduction = 9%.
Step 4 Adjust curve numbers for conservation tillage.
CN = (CN from step 1) x (1-(CN reduction %/100)).
(a) Soybeans following corn (corn residue).
CN = 78 X (l-(4/100)) = 74.9; use CN = 75.
(b) Corn following soybeans (soybean residue).
CN = 78 x (l-(9/100)) = 71
(c) Average CN for cultivated area, 50% of each crop.
CN = (75 CN soybeans + 71 CN corn)/2
CN = 73.
Step 5 Direct runoff in inches with conservation tillage with 3.0" rainfall
and CN = 73: runoff = 0.9" (NEH, Sect. 4, figure 10.1). Without
conservation tillage, CN = 78; runoff would be 1.1". This amounts
to an 18% reduction in runoff.
-------
APPENDIX 2
-------
RflIM
3-
CHESflPEflKE RFIY DRILY PRECIPITRTION
YERR=71
TOTAL -- 4o.S^l i^ .
LJ
I
O
z
g
CL
u
u ,
a: 1
Q.
0-
1,
3
1
lil.JI.li
. ill
1
1 II
.111.
J.
i ' > — i — i — i — i — i — i—
100
J
J
.•II.I...II...L i
..i,.
200
DRY
I
i
mt
l_
~l 1 1 1 r
(-
|
1 ' 1
300
1
J.
jj
100
-------
CHESflPEflKE BflY OfllLY PRECIPITflTION
YEftR=75
RflIN
in
ui
I
O
u
u
o:
CL
iLiI
100
I
200
DRY
300
100
-------
CHESflPEflKE BflY DRILY PRECIPITflTION
YEflR=76
60
LJ
I
o
z
o
Q.
O
LJ
a:
Q_
RfllH
3
2-
1 -
,
0 -
0
ll. .1
I ....1
i
t
nil
1 „
1 ' •-
100
yc
1
« KL
t,
f -" 1
.r ILT
iiil
l H L. -
2
00
T--i. O
III
1 T" "1"
} u^.
in
..i »
i..
3
.. ......i
00
l i
.1.1 J,
• i i i i |
'100
-------
RflIN
3-
CHESflPEflKE BflY DfllLY PRECIPITflTION
YEflR=77
= 31,03
60
LJ
I
O
o
LJ
-------
CHESflPEflKE BflY DF1ILY PRECIPITflTION
YEflR=78
CO
LJ
I
o
o
Q.
O
LJ
CtL
Q.
RflIN
3
2-
,
0-
(
j
1
i ..i
ii, ,.,Jj
)
YC«K«.
.!J.|.
A
111
i > | i 1 1 1 r—
100
-1
..1
f
1 —
If
1
— I
T
ii.
^L
...III,
- - ^<*.S uo .
i
1
1 1 1 1 III 1 1 i i
111] Jlljlli I.U. .,.4,1.1 JL,!..,
1 !, 1 1 1 1 , 1 1 . 1 | 1 1 I I I 1 1 1 1 |
200 300 100
DRY
-------
APPENDIX 3
-------
SOIL 1. GALESTOWN
DEPTH
0-24"
TEXTURE
LS
POROS.
0.40
ER15
0.05
FUL
0.4
CCN&
3.3
Source: Soils 5 sheet and CREAMS manual.
24"
UL(1)
UL(2)
UL(3)
UL(4)
UL(5)
UL(6)
UL(7)
1"
3"
20"
Rooting Depth, RD = 24"
(Soil Layer Depth) (RD)
1/36(24") = 0.67"
5/36(24") = 3.33"
1/6(24") = 4.0"
Saturated
Conductivity, RC, for good,
straight row crops, Hydrologic
Group A = 0.45
(CRR, p 184)
UL = (POROS - ER15) (RD) (Soil Layer Depth)
UL(1)
UL(2)
UL(3)
UL(4)
UL(5)
UL(6)
UL(7)
(0.4
(0.4
(0.4
1.40
1.40
1.40
1.40
0.05)(0.67)
0.05)(3.33)
0.05H4.0)
= 1
0.23
1.17
40
7 - Layer Averages
FUL = 0.40
COMA = 3.30
ER15 = 0.05
PCROS = 0.40
K - factor = 0.17
(Soils 5 sheet)
-------
SOIL 2. NORFOLK
DEPTH TEXTURE
PQROS.
ER15
Source: Soils 5 sheet and CREAMS manual.
FUL
COMA
0-16"
16-24"
LS,LFS
SL
0.40
0.40
0.05
0.08
0.49
0.44
3.3
3.5
24"
UL(1)
UL(2)
UL(3)
UL(4)
UL(5)
UL(6)
UL(7)
1"
3"
i fi
J.O
Rooting Depth, RD = 24"
(Soil Layer Depth) (RD)
1/36(24") = 0.67"
5/36(24") = 3.33"
1/6(24") = 4.0"
Saturated Hydraulic
Conductivity. RC. for good,
straight row crops, Hydrologic
Group B = 0.21
(CRR, p 184)
UL = (FORDS - ER15)(RD)(Soil Layer Depth)
UL(1)
UL(2)
UL(3)
UL(4)
UL(5)
UL(6)
UL(7)
(0.4
(0.4
(0.4
1.40
1.40
(0.4
1.28
0.05)(0.67)
0.05)(3.33)
0.05)(4.0)
= 1
0.23
1.17
40
- 0.08)(4.0) = 1.28
7 — Laver
FUL = 0.4433
COMA = 3.40
BR15 = 0.06
FORDS = 0.40
K - factor = 0.17
(Soils 5 sheet)
-------
SOIL 3. CECIL
DEPTH TEXTURE
PCROS.
BR15
Source: Soils 5 sheet and CREAMS manual.
FUL
CCNA
0-8"
8-12"
12-24
SL
SCLfCL
C
0.40
.4, .4
0.47
0.08
.18, .22
0.28
0.44
.54, .72
0.58
3.5
4.0,4
3.5
.0
24"
UL(1)
UL(2)
UL(3)
UL(4)
UL(5)
UL(6)
UL(7)
1"
Q"
3"
4"
20"
T "511
J.Z"
Rooting Depth, RD = 24"
(Soil Layer Depth) (RD)
1/36(24") = 0.67"
5/36(24") = 3.33"
1/6(24") = 4.0"
Saturated Hydraulic
Conductivityf RC. for good,
straight row crops, Hydrologic
Group B = 0.21
(CRR, p 184)
UL = (FCRQS - ER15) (RD) (Soil Layer Depth)
UL(1) = (0.4 - 0.08)(0.67) = 0.2144
UL(2) = (0.4 - 0.08)(3.33) = 1.0656
UL(3) = (0.4 - 0.18M4.0) = 0.88
UL(4) = (0.4 - 0.22)(4.0) = 0.72
UL(5) = (0.47- 0.28)(4.0) = 0.76
UL(6) = 0.76
UL(7) = 0.76
7 — Layer Averages
FUL = 0.527
CCNA. = 3.57
BR15 = 0.20
PCRQS = 0.43
K - factor = 0.28
(Soils 5 Sheet)
-------
SOIL 4. AND 5. CECIL
DEPTH TEXHJRE
PCROS.
BR15
FUL
CCNA
0-8" SCL 0.40 0.18 0.54 4.0
8-12" CL 0.40 0.22 0.72 4.0
12-24 C 0.47 0.28 0.58 3.5
Source: Soils 5 sheet and CREftMS manual.
__ -Tk^u-bA. -i « — TV*...- 1 1~ TO-* *"l * It
24"
UL(1)
UL(2)
UL(3)
UL(4)
UL(5)
UL(6)
UL(7)
1" (Soil Layer Depth) (RD)
8" 1/36(24") = 0.67"
3" 5/36(24") = 3.33"
.... T /cf>A«\ A f\n
±/O\£li ) — 4.U
4"
Saturated Hydraulic
Conductivity , RCf for good,
20" straight row crops, Hydrologic
12" Group B = 0.21
(CRR, p 184)
UL = (PCRDS - BRISXKDXSoil Layer Depth)
UL(1) = (0.4 - 0.18X0.67) = 0.1474
UL(2) = (0.4 - 0.20)(3.33) = 0.666
UL(3) = (0.4 - 0.20) (4.0) = 0.80
UL(4) = (0.4 - 0.22)(4.0) = 0.72
UL(5) = (0.47- 0.28) (4.0) = 0.76
UL(6) = 0.76
UL(7) = 0.76
7 — Laver Averaaes
FUL = 0.61
CCNA = 3.786
BR15 = 0.2343
PCROS = 0.43
K - factor =0.28
(Soils 5 sheet)
-------
SOIL 6. PENN LOAM
(0 - 8% Slope)
DEPTH TEXTURE
FORDS.
ER15
Source: Soils 5 sheet and CREAMS manual.
FUL
COMA
0-8"
8-24"
L
SIL
0.40
0.43
0.11
0.12
0.52
0.64
4.5
4.5
24"
UL(1)
UL(2)
UL(3)
UL(4)
UL(5)
UL(6)
UL(7)
8"
1
1 Cll
ID
Rooting Depth, RD = 24"
(Soil Layer Depth) (RD)
1/36(24") = 0.67"
5/36(24") = 3.33"
1/6(24") = 4.0"
Saturated Hydraulic
Conductivity f RC, for good,
straight row crops, Hydrologic
Group C = 0.10
(average between 0.5 - 0.15)
(CREAMS Manual)
UL = (FORDS - ER15) (RDMSoil Layer Depth)
UL(1) = (0.4 - 0.11)(0.67) = 0.19
UL(2) = (0.4 - 0.11H3.33) = 0.97
UL(3) = (0.4 - 0.11M4.0) = 1.16
UL(4) = (0.43- 0.12)(4.0) = 1.24
UL(5) = 1.24
UL(6) = 1.24
UL(7) = 1.24
7 — Laver Averages
FUL = 0.58
CONA = 4.5
BR15 = 0.115
POROS = 0.415
K - factor = 0.32
CNII: 85/82
C - factor
base .22 .25 .25 .22 .19 .16 .22
alt. .19 .14 .14 .13 .11 .09 .19
-------
APPENDIX 4
-------
Summary
5-yp. Simulation (1974-78)
Continuous Corn w/One Fertilizer Application (Broadcast)
Field size - 35 acres ZX Slope
PREC1P RUNOFF SOIL LOSS
(in) (in) (t/ac)
Soil 1 (Loamy Sand)
Base Scenario (CM 1 1 =67)
1974
1975
1976
1977
1978
Mean
Std Dev
40.590
52.780
42.890
39.030
46.500
44.358
4.9O4
0.020
0.050
0.130
0.000
0.160
0.072
0.062
0.000
0.000
0.000
0.000
0.000
0.000
0.000
TOT N
TOT P N LEACHED
K UPTAKE E
........ ^ n8/ nuj
0.016
0.035
0.090
0.000
0.223
0.073
0.081
0.002
0.004
0.012
0.000
0.034
0.010
0.013
95.552
89.031
74.406
103.393
135.180
99.512
20.214
190.472
184.873
182.529
163.723
134.206
171.160
20.548
NRICHHENT
RATIO
11.206
11.493
11.173
11.407
Alternate Scenario (CHI 1=65)
1974
1975
1976
1977
1978
Mean
Std Dev
Percent Reduction
il 2 (Loamy Sand, Fine
Base Scenario (CII=78)
1974
1975
1976
1977
1978
Mean
Std Dev
Alternate Scenario (CM
1974
1975
1976
1977
1978
Mean
Std Dev
40.590
52.780
42.890
39.030
46.500
44.358
4.904
Loamy Sand,
40.590
52.780
42.890
39.030
46.500
44.358
4.904
=76)
40.590
52.780
42.890
39.030
46.500
44.358
4.904
0.000
0.010
0.090
0.000
0.100
0.040
0.045
44.444
0.000
0.000
0.000
0.000
0.000
0.000
0.000
ERR
0.000
0.007
0.062
0.000
0.131
0.040
0.051
45.150
0.000
0.001
0.008
0.000
0.020
0.006
0.008
44.636
95.583
89.050
74.441
103.389
135.397
99.572
20.279
-0.060
190.472
184.872
182.529
163.723
134.112
171.142
20.582
0.011
1 1 . 206
11.238
11.472
Sandy Loam)
0.510
0.900
1.010
0.300
1.310
0.806
0.360
0.370
0.650
0.740
0.210
0.990
0.592
0.275
0.020
0.030
0.020
0.000
0.070
0.028
0.023
0.010
0.010
0.010
0.000
0.030
0.012
0.010
0.762
0.803
0.791
0.302
2.094
0.950
0.602
0.472
0.487
0.581
0.208
1.474
0.645
0.433
0.115
0.124
0.106
0.027
0.342
0.143
0.106
0.058
0.058
0.082
0.019
0.226
0.088
0.072
83.573
81.587
69.873
97.452
124.174
91.332
18.610
84.747
81.866
70.216
97.905
125.747
92.096
18.992
199.281
190.197
191.317
168.240
144.225
178.652
20.065
198.738
190.111
191.317
168.240
143.194
178.320
20.300
7.186
6.540
7.868
11.203
5.164
7.689
7.469
7.422
11.257
4.842
Percent Reduction
26.551 57.143 32.172 38.059 -0.837
0.186
Soil 1 Galestown, loamy sand
Soil 2 Norfolk, loamy sand, loamy fine sand, sandy loam
Soil 3 Cecil, sandy loam, sandy clay loam, clay loam, clay
Soil 4 Cecil, sandy clay loam, clay loam, clay
Soil 5 Cecil, sandy clay loam, clay loam, clay
Soil 6 Penn Loam, loam, silt loam
-------
Sumnary, con't.
5-yr. Simulation (1974-78)
Continuous Corn w/One Fertilizer Application (Broadcast)
Field size - 35 acres 2X Slope
PRECIP RUNOFF SOIL LOSS
(in) (in) (t/ac)
Soil 3 (Sandy Loam, Sandy
Base Scenario (CNII=78)
1974
1975
1976
1977
1978
Mean
Std Dev
Clay Loam,
40.590
52.780
42.890
39.030
46.500
24.643
22.343
TOT N
TOT P N LEACHED
N UPTAKE E
MRICHMENT
RATIO
Clay Loam, Clay)
0.670
1.290
1.420
0.530
1.740
0.628
0.658
0.040
0.100
0.040
0.010
0.140
0.037
0.048
1.266
1.306
1.215
0.566
3.316
0.852
1.031
0.189
0.210
0.145
0.060
0.572
0.131
0.176
75.351
83.762
75.327
111.780
110.135
57.044
46.043
188.988
212.038
180.246
152.406
179.419
114.137
89.698
3.620
3.177
4.356
5.525
3.283
Alternate Scenario (CNII=76)
1974
1975
1976
1977
1978
Mean
Std Dev
Percent Reduction
Soil 4 (Sandy Clay Loam,
Base Scenario (CI1«78)
1974
1975
1976
1977
1978
Mean
Std Dev
Alternate Scenario (C1I
1974
1975
1976
1977
1978
Mean
Std Oev
40.590
52.780
42.890
39.030
46.500
44.358
4.904
Clay Loam,
40.590
52.780
42.890
39.030
46.500
44.358
4.904
=76)
40.590
52.780
42.890
39.030
46.500
44.358
4.904
0.500
1.000
1.100
0.340
1.350
0.858
0.379
-36.673
Clay)
0.060
1.920
1.970
0.730
2.170
1.530
0.607
0.640
1.550
1.600
0.520
1.720
1.206
0.516
0.020
0.040
0.020
0.010
0.060
0.030
0.018
18.182
0.060
0.130
0.070
0.020
0.170
0.090
0.053
0.040
0.050
0.040
0.010
0.070
0.042
0.019
0.891
0.868
0.939
0.329
2.299
1.065
0.655
-25.003
1.610
2.149
1.906
0.765
4.216
2.129
1.143
1.153
1.509
1.395
0.499
3.127
1.537
0.869
0.129
0.115
0.119
0.028
0.368
0.152
0.114
-16.106
0.228
0.318
0.266
0.076
0.711
0.320
0.211
0.162
0.191
0.171
0.043
0.502
0.214
0.153
76.585
83.908
75.937
112.605
111.958
92.199
16.636
-61.626
67.678
82.455
70.084
106.556
104.166
86.188
16.456
69.341
82.841
70.877
107.447
106.063
87.314
16.554
188.988
212.038
180.246
152.406
178.135
182.363
19.206
-59.775
187.934
212.506
180.628
153.271
185.847
184.037
18.905
187.934
212.506
180.628
153.271
184.564
183.780
18.888
3.424
3.279
3.959
5.589
3.257
2.686
2.639
3.047
3.573
2.712
2.542
2.711
2.816
3.598
2.699
Percent Reduction
21.176 53.333 27.830 33.102 -1.306 0.139
-------
Sunnary
5-yr. Simulation (1974-78)
Continuous Corn w/One Fertilizer Application (Broadcast)
Field size - 35 acres AX Slope
PRECIP RUNOFF SOIL LOSS
(in) , (in) (t/ac)
Soil 1 (Loamy Sand)
Base Scenario (CII=67)
1974
1975
1976
1977
1978
Mean
Std Dev
40.590
52.780
42.990
39.030
46.500
44.358
4.904
0.020
0.050
0.130
0.000
0.160
0.072
0.062
0.000
0.000
0.010
0.000
0.020
0.006
0.008
TOT N
0.016
0.035
0.134
0.000
0.300
0.097
0.112
TOT P N
* 1, _ /L
•---(kg/n
0.002
0.004
0.028
0.000
0.062
0.019
0.024
LEACHED
aj. ......
95.552
89.031
74.406
103.393
135.180
99.512
20.214
N UPTAKE E
190.472
184.873
182.529
163.723
134.206
171.160
20.548
NRICHMENT
RATIO
11.183
11.003
9.752
7.716
Alternate Scenario (CHI 1=65)
1974
1975
1976
1977
1978
Mean
Std Oev
Percent Reduction
'I 2 (Loamy Sand, Fine
ase Scenario (CII=78)
1974
1975
1976
1977
1978
Mean
Std Oev
40.590
52.780
42.890
39.030
46.500
44.358
4.904
Loamy Sand,
40.590
52.780
42.890
39.030
46.500
44.358
4.904
0.000
0.010
0.090
0.000
0.100
0.040
0.045
44.444
0.000
0.000
0.000
0.000
0.010
0.002
0.004
66.667
0.000
0.007
0.062
0.000
0.131
0.040
0.051
58.922
0.000
0.001
0.008
0.000
0.020
0.006
0.008
69.927
95.583
89.050
74.441
103.389
135.397
99.572
20.279
-0.060
190.472
184.872
182.529
163.723
134.112
171.142
20.582
0.011
11.860
10.710
8.351
Sandy Loam)
0.510
0.900
1.010
0.300
1.310
0.806
0.360
0.100
0.120
0.090
0.010
0.220
0.108
0.067
1.047
1.117
1.002
0.346
2.517
1.206
0.712
0.217
0.237
0.182
0.043
0.494
0.235
0.147
83.573
81.587
69.873
97.452
124.174
91.332
18.610
199.281
190.197
191.317
168.240
144.225
178.652
20.065
3.815
4.442
4.680
9.564
4.209
Alternate Scenario (CII=76)
1974
1975
1976
1977
1978
Mean
Std Oev
40.590
52.780
42.890
39.030
46.500
44.358
4.904
0.370
0.650
0.740
0.210
0.990
0.592
0.275
0.040
0.040
0.050
0.000
0.080
0.042
0.026
0.639
0.621
0.672
0.208
1.688
0.766
0.491
0.118
0.106
0.114
0.019
0.303
0.132
0.093
84.747
81.866
70.216
97.905
125.747
92.096
18.992
198.738
190.111
191.317
168.240
143.194
178.320
20.300
4.164
4.446
3.999
10.639
4.251
Percent Reduction
26.551 61.111 36.496 43.778 -0.837
0.186
Soil 1 Galestown, loamy sand
Soil 2 Norfolk, loamy sand, loamy fine sand, sandy loam
Soil 3 Cecil, sandy loam, sandy clay loam, clay loam, clay
Soil 4 Cecil, sandy clay loam, clay loam, clay
Soil 5 Cecil, sandy clay loam, clay loam, clay
Soil 6 Penn Loam, loam, silt loam
-------
Summary, con't.
5-yr. Simulation (1974-78)
Continuous Corn w/One Fertilizer Application (Broadcast)
Field size - 35 acres 4X Slope
PRECIP RUNOFF SOIL LOSS
(in) (in) (t/ac) <
Soil 3 (Sandy Loam, Sandy
Base Scenario (CII=7S)
1974
1975
1976
1977
1978
Mean
Std Dev
Alternate Scenario (CMI
1974
1975
1976
1977
1978
Mean
3rd Dev
Percent Reduction
4 (Sandy Clay Loam.
Base Scenario (CHI 1=78)
1974
1975
1976
1977
1978
Mean
Std Oev
Clay Loam,
40.590
52.780
42.890
39.030
46.500
44.358
4.904
1=76)
40.590
52.780
42.890
39.030
46.500
44.358
4.904
Clay Loam,
40.590
52.780
42.890
39.030
46.500
44.358
4.904
TOT N
TOT P N LEACHED
H UPTAKE Ei
KIRICHMEMT
RATIO
Clay Loam, Clay)
0.670
1.290
1.420
0.530
1.740
1.130
0.459
0.500
1.000
1.100
0.340
1.350
0.858
0.379
24.071
Clay)
0.860
1.920
1.970
0.730
2". 170
1.530
0.607
0.190
0.310
0.170
0.030
0.500
0.240
0.157
0.070
0.120
0.110
0.010
0.220
0.106
0.069
55.833
0.210
0.430
0.260
0.060
0.610
0.314
0.189
1.646
1.943
1.641
0.688
4.159
2.015
1.152
1.059
1.171
1.186
0.373
2.772
1.312
0.789
34.880
2.046
3.001
2.396
0.931
5.349
2.745
1.466
0.326
0.439
0.299
0.104
0.875
0.409
0.257
0.189
0.224
0.208
0.044
0.538
0.241
0.162
41.105
0.385
0.625
0.442
0.137
1.118
0.541
0.328
75.351
83.762
75.327
111.780
110.135
91.271
16.374
76.585
83.908
75.937
112.605
111.958
92.199
16.636
-1.017
67.678
82.455
70.084
106.556
104.166
86.188
16.456
188.988
212.038
180.246
152.406
179.419
182.620
19.156
188.988
212.038
180.246
152.406
178.135
182.363
19.206
0.141
187.934
212.506
180.628
153.271
185.847
184.037
18.905
2.731
2.144
3.232
5.241
2.363
2.732
2.256
2.976
5.416
2.409
2.422
1.849
2.536
3.333
2.002
Alternate Scenario (CN1I=76)
1974
1975
1976
1977
1978
Mean
Std Dev
40.590
52.780
42.890
39.030
46.500
44.358
4.904
0.640
1.550
1.600
0.520
1.720
1.206
0.516
0.080
0.190
0.140
0.030
0.280
0.144
0.087
1.260
2.044
1.767
0.633
3.715
1.884
1.034
0.200
0.384
0.305
0.091
0.714
0.339
0.212
69.341
82.841
70.877
107.447
106.063
87.314
16.554
187.934
212.506
180.628
153.271
184.564
183.780
18.888
2.532
1.908
2.447
3.329
2.043
Percent Reduction
21.176 54.140 31.371 37.397 -1.306
0.139
-------
Surma ry
5-yr. Simulation (1974-78)
Continuous Corn w/One FertiIizer Application (Broadcast)
Field size - 35 acres 6X Slope
PRECIP RUNOFF SOIL LOSS
(in) (in)
Soil 1 (Loamy Sand)
Base Scenario (CM II
1974
1975
1976
1977
1978
Mean
Std Dev
Alternate Scenario
1974
1975
1976
1977
1978
Mean
Std Dev
=67)
40.590
52.780
42.890
39.030
46.500
44.358
4.904
(CN11=65)
40.590
52.780
42.890
39.030
46.500
44.358
4.904
0.020
0.050
0.130
0.000
0.160
0.072
0.062
0.000
0.010
0.090
0.000
0.100
0.040
0.045
(t/ac)
IS8BS8O8**
0.000
0.010
0.020
0.000
0.060
0.018
0.022
0.000
0.000
0.010
0.000
0.020
0.006
0.008
TOT N
TOT P N LEACHED
N UPTAKE ENRICHMENT
RATIO
0.016
0.080
0.167
0.000
0.429
0.138
0.157
0.000
0.007
0.106
0.000
0.208
0.064
0.082
0.002
0.020
0.040
0.000
0.108
0.034
0.040
0.000
0.001
0.024
0.000
0.048
0.015
0.019
95.552
89.031
74.406
103.393
135.180
99.512
20.214
95.583
89.050
74.441
103.389
135.397
99.572
20.279
190.472
184.873
182.529
163.723
134.206
171.160
20.548
190.472
184.872
182.529
163.723
134.112
171.142
20.582
11.411
8.086
7.080
6.467
11.818
7.366
7.088
Percent Reduction
44.444 66.667 53.513 57.286 -0.060
0.011
2 (Loamy Sand, Fine Loam/ Sand, Sandy Loam)
il
3ase Scenario (CHI 1=78)
1974
1975
1976
1977
1978
Mean
Std Dev
Alternate Scenario (CNII-76)
1974
1975
1976
1977
1978
Mean
Std Dev
Percent Reduction
40.590
52.780
42.890
39.030
46.500
44.358
4.904
6)
40.590
52.780
42.890
39.030
46.500
44.358
4.904
0.510
0.900
1.010
0.300
1.310
0.806
0.360
0.370
0.650
0.740
0.210
0.990
0.592
0.275
0.
170
0.200
0.170
0.030
0.430
0.200
0.129
0
0
0
0
0
0
0
.060
.070
.080
.010
.170
.078
.052
1.180
1.348
1.316
0.379
3.057
1.456
0.875
0.705
0.809
0.813
0.253
1.974
0.911
0.570
0.690
0.320
0.295
0.055
0.689
0.410
0.246
0.142
0.064
0.165
0.035
0.406
0.162
0.131
83.573
81.587
69.873
97.452
124.174
91.332
18.610
84.747
81.866
70.216
97.905
125.747
92.096
18.992
199.281
190.197
191.317
168.240
144.225
178.652
20.065
198.738
190.111
191.317
168.240
143.194
178.320
20.300
3.
4.
4.
7.
897
331
423
.431
3.518
4
4
4
7
3
.124
.770
.267
.599
.577
26.551 61.000 37.468 60.431 -0.837
0.186
Soil 1 Galestown, loamy sand
Soil 2 Norfolk, loamy sand, loamy fine sand, sandy loam
Soil 3 Cecil, sandy loam, sandy clay loam, clay loam, clay
Soil 4 Cecil, sandy clay loam, clay loam, clay
Soil 5 Cecil, sandy clay loam, clay loam, clay
Soil 6 Penn Loam, loam, silt loam
-------
Summary, can't.
S-yr. Simulation (1974-78)
Continuous Corn w/One Fertilizer Application (Broadcast)
Field size - 35 acres 6X Slope
PREC1P RUNOFF SOIL LOSS
(in) (in) (t/ac)
Soil 3 (Sandy Loam, Sandy Clay Loam,
Base Scenario (CM! I
1974
1975
1976
1977
1978
Mean
Std Dev
Alternate Scenario
1974
1975
1976
1977
1978
Mean
Std Oev
=78)
40.
52.
42.
39.
46.
44.
4.
(CNII=76)
590
780
890
030
500
358
904
40.S90
52.780
42.890
39.030
461500
44.358
4
.904
Percent Reduction
Soil 4 (Sandy Clay Loam, Clay Loam.
Base Scenario (CNI
1974
1975
1976
1977
1978
Mean
Std Dev
Alternate Scenario
1974
1975
1976
1977
1978
Mean
Std Dev
1=78)
40
.590
52.780
42
39
46
44
4
(CM 11 =76)
40
52
42
39
46
44
4
.890
.030
.500
.358
.904
.590
.780
.890
.030
.500
.358
.904
TOT
N
TOT P N LEACHED
N UPTAKE El
Clay Loam, Clay)
0.670
1.290
1.420
0.530
1.740
1.130
0.459
0.500
1.000
1.100
0.340
1.350
0.858
0.379
24.071
Clay)
0.860
1.920
1.970
0.730
2.170
1.530
0.607
0.640
1.550
1.600
0.520
1.720
1.206
0.516
0.440
0.530
0.400
0.070
0.980
0.484
0.293
0.170
0.230
0.260
0.040
0.460
0.232
0.137
52.066
0.440
0.880
0.540
0.120
1.180
0.632
0.366
0.200
0.420
0.370
0.070
0.620
0.336
0.189
2.
2.
2.
0.
5.
2.
1.
281
468
246
795
210
600
436
1.331
1.465
1.575
0.495
3.448
1.663
0.970
36.035
2
4
3
1
6
3
1
1
2
2
0
4
2
1
.609
.037
.146
.087
.627
.501
.834
.673
.614
.339
.806
.609
.408
.265
0.555
0.628
0.516
0.143
1.253
0.619
0.359
0.287
0.330
0.348
0.088
0.782
0.367
0.227
40.735
0.587
0.998
0.712
0.192
1.579
0.814
0.462
0.349
0.589
0.511
0.154
1.036
0.528
0.295
75.351
83.762
75.327
111.780
110.135
91.271
16.374
76.585
83.908
75.937
112.605
111.958
92.199
16.636
-1.017
67.678
82.455
70.084
106.556
104.166
86.188
16.456
69.341
82.841
70.877
107.447
106.063
87.314
16.554
188.988
212.038
180.
152.
179.
182.
19.
188.
246
406
419
620
156
988
212.038
180.246
152.406
178.135
HR1CHMENT
RATIO
1.932
2.036
2.535
4.166
2.060
2.014
2.177
2.127
4.081
1.930
182.363
19.206
0.141
187.934
212.506
180.628
153
.271
185.847
184
18
187
.037
.905
.934
212.506
180.628
153
184
183
18
.271
.564
.780
.888
1.879
1.693
2.174
2.852
1.809
1.710
1.674
1.966
2.728
1.663
Percent Reduction
21.176 46.835 31.216 35.145 -1.306 0.139
-------
Summary
5-yr. Simulation (1974-78)
Continuous Corn w/One Fertilizer Application (Broadcast}
Field size - 35 acres 8X Slope
PREC1P RUNOFF SOIL LOSS TOT N TOT P N LEACHED N UPTAKE
(in) (in) (t/ac) (kg/ha)
ENRICHMENT
RATIO
Soil 2 (Loamy Sand, Fine Loamy Sand, Sandy Loam)
Base Scenario (CHI 1=78)
1974
1975
1976
1977
1978
Mean
Std Oev
40.590 0.510 0.240 1.377 0.336 83.573 199.281
52.780 0.900 0.380 1.837 0.496 81.587 190.197
42.890 1.010 0.270 1.622 0.405 69.873 191.317
39.030 0.300 0.070 0.552 0.117 97.452 168.240
46.500 1.310 0.720 3.781 0.949 124.174 144.225
44.358 0.806 0.336 1.834 0.461 91.332 178.652
4.904 0.360 0.216 1.067 0.275 18.610 20.065
3.512
3.219
4. 545
6.450
2.828
Alternate Scenario (CNII=76)
1974
1975
1976
1977
1978
Hean
Std Oev
Percent Reduction
il 3 (Sandy Loam, Sandy
Base Scenario (CM 1 1 =78)
1974
1975
1976
1977
1978
Hean
Std Dev
40.590 0.370 0.100 0.819 0.182 84.747 198.738
52.780 0.650 0.140 0.990 0.239 81.866 190.111
42.890 0.740 0.130 1.016 0.238 70.216 191.317
39.030 0.210 0.030 0.286 0.047 97.905 168.240
46.500 0.990 0.310 2.335 0.536 125.747 143.194
44.358 0.592 0.142 1.089 0.248 92.096 178.320
4.904 0.275 0.092 0.676 0.160 18.992 20.300
26.551 57.738 40.611 46.086 -0.837 0.186
Clay Loam, Clay Loam, Clay)
40.590 0.670 0.600 2.572 0.659 75.351 188.988
52.780 1.290 0.910 3.337 0.941 83.762 212.038
42.890 1.420 0.710 2.958 0.773 75.327 180.246
39.030 0.530 0.130 0.937 0.194 111.780 152.406
46.500 1.740 1.640 6.582 1.747 110.135 179.419
44.358 1.130 0.798 3.277 0.863 91.271 182.620
4.904 0.459 0.493 1.844 0.507 16.374 19.156
3.476
3.447
4.465
6.858
2.655
1.903
1.786
2.139
3.562
1.776
-Alternate Scenario (CNII-76)
1974
1975
1976
1977
1978
Hean
Std Oev
Percent Reduction
40.590 0.500 0.230 1.500 0.348 76.585 188.988
52.780 1.000 0.450 2.085 0.553 83.908 212.038
42.890 1.100 0.390 1.950 0.483 75.937 180.246
39.030 0.340 0.070 0.586 0.121 112.605 152.406
46.500 1.350 0.880 4.350 1.106 111.958 178.135
44.358 0.858 0.404 2.094 0.522 92.199 182.363
4.904 0.379 0.272 1.244 0.327 16.636 19.206
24.071 49.373 36.095 39.486 -1.017 0.141
2.020
1.792
2.131
3.308
1.625
Soil 1 Galestown, loamy sand
Soil 2 Norfolk, loamy sand, loamy fine sand, sandy loam
Soil 3 Cecil, sandy loam, sandy clay loam, clay loam, clay
Soil 4 Cecil, sandy clay loam, clay loam, clay
Soil 5 Cecil, sandy clay loam, clay loam, clay
Soil 6 Penn Loam, loam, silt loam
-------
Summary, con't.
5-yr. Simulation (1974-78)
Continuous Corn w/One Fertilizer Application (Broadcast)
Field size - 35 acres 8X Slope
PRECIP RUNOFF SOIL LOSS
On) (in) (t/ac)
TOT N
TOT P N LEACHED
N UPTAKE E
NRICHMEI
RATIO
IT
Soil 4 (Sandy Clay Loan, Clay Loam, Clay)
Base Scenario (CNII
1974
1975
1976
1977
1978
Mean
Std Dev
Alternate Scenario
1974
1975
1976
1977
1978
Mean
Std Oev
=78>
40,
52
42
39
46
44
4
CCNII=76)
40
52
42
39
46
44
4
.590
.780
.890
.030
.500
.358
.904
.590
.780
.890
.030
.500
.358
.904 '
0.860
1.920
1.970
0.730
2.170
1.530
0.607
0.640
1.550
1.600
0.520
1.720
1.206
0.516
0.760
1.670
0.960
0.220
2.040
1.130
0.650
0.320
0.680
0.600
0.140
1.050
0.558
0.313
3.293
5.589
4.039
1.421
8.220
4.512
2.288
1.956
3.173
2.957
0.947
5.555
2.918
1.538
0.833
1.557
1.033
0.313
2.152
1.178
0.629
0.451
0.790
0.733
0.204
1.377
0.711
0.394
67.678
82.455
70.084
106.556
104.166
86.188
16.456
69.341
82.841
70.877
107.447
106.063
87.314
16.554
187.
212.
180.
153.
185.
184.
18.
934
506
628
271
847
037
905
187.934
212.506
180.628
153.271
184.564
1
1
1
2
1
1
1
1
2
1
.617
.460
.977
.624
.596
.660
.518
.830
.507
.526
183.780
18.888
Percent Reduction 21.176 50.619 35.340 39.620 -1.306 0.139
-------
Summary
5-yr. Simulation (1974-78)
Continuous Corn u/One Fertilizer Application (Broadcast)
Field size - 35 acres 10% Slope
PRECIP RUNOFF SOIL LOSS TOT N TOT P N LEACHED N UPTAKE
(in) (in) (t/ac) (kg/ha)
ENRICHMENT
RATIO
Soil 2 (Loamy Sand. Fine Loam/ Sand. Sandy Loam)
Base Scenario (CNII=78)
1974
1975
1976
1977
1978
Mean
Std Dev
40.590 0.510 0.350 1.647 0.433 83.573 199.281
52.780 0.900 0.620 2.379 0.691 81.587 190.197
42.890 1.010 0.410 1.915 0.510 69.873 191.317
39.030 0.300 0.120 0.659 0.155 97.452 168.240
46.500 1.310 1.140 4.599 1.244 124.174 144.225
44.358 0.806 0.528 2.240 0.607 91.332 178.652
4.904 0.360 0.345 1.307 0.362 18.610 20.065
3.027
2.512
4.103
5.819
2.289
Alternate Scenario (CNI1=76)
1974
1975
1976
1977
1978
Mean
Std Dev
Percent Reduction
3i I 3 (Sandy Loam. Sandy
Base Scenario (CNII=78)
1974
1975
1976
1977
1978
Mean
Std Dev
40.590 0.370 0.140 0.926 0.221 84.747 198.738
52.780 0.650 0.250 1.247 0.331 81.846 190.111
42.890 0.740 0.190 1.158 0.289 70.216 191.317
39.030 0.210 0.060 0.432 0.099 97.905 168.240
46.500 0.990 0.530 2.813 0.708 125.747 143.194
44.358 0.592 0.234 1.315 0.330 92.096 178.320
4.904 0.275 0.161 0.800 0.205 18.992 20.300
26.551 55.682 41.287 45.665 -0.837 0.186
Clay Loam, Clay Loam, Clay)
40.590 0.670 0.810 3.041 0.828 75.351 188.988
'52.780 1.290 1.530 4.466 1.347 83.762 212.038
42.890 1.420 0.980 3.507 0.970 75.327 180.246
39.030 0.530 0.210 1.153 0.272 111.780 152.406
46.500 1.740 2.510 8.136 2.307 110.135 179.419
44.358 1.130 1.208 4.061 1.145 91.271 182.620
4.904 0.459 0.775 2.305 0.676 16.374 19.156
3.195
2.478
4.139
5.990
2.165
1.801
1.590
2.090
3.201
1.598
Alternate Scenario (CNII=76)
1974
1975
1976
1977
1978
Mean
Std Dev
Percent Reduction
40.590 0.500 0.340 1.731 0.431 76.585 188.988
52.780 1.000 0.730 2.709 0.778 83.908 212.038
42.890 1.100 0.570 2.358 0.629 75.937 180.246
39.030 0.340 0.120 0.745 0.178 112.605 152.406
46.500 1.350 1.220 5.009 1.343 111.958 178.135
44.358 0.858 0.596 2.510 0.672 92.199 182.363
4.904 0.379 0.374 1.416 0.391 16.636 19.206
24.071 50.662 38.180 41.314 -1.017 0.141
1.897
1.570
2.065
2.923
1.556
Soil 1 Galestown, loamy sand
Soil 2 Norfolk, loamy sand, loamy fine sand, sandy loam
Soil 3 Cecil, sandy loam, sandy clay loam, clay loam, clay
Soil 4 Cecil, sandy clay loam, clay loam, clay
Soil 5 Cecil, sandy clay loam, clay loam,
Soil 6 Penn Loam, loam, silt loam
clay
-------
Suimary, con't.
5-yr. Simulation (1974-78)
Continuous Corn w/One FertiHzer Application (Broadcast)
Field size - 35 acres 10X Slope
PRECIP RUNOFF SOIL LOSS
(in) Cin) (t/ec)
TOT N
TOT P N LEACHED
N UPTAKE E
NRICHMENT
RATIO
Soil 4 (Sandy Clay Loam, Clay Loam, Clay)
Base Scenario (CHI I =78)
1974
1975
1976
1977
1970
Mean
Std Dev
Alternate Scenario
1974
1975
1976
1977
1978
Mean
Std Oev
40.
52
42
39
.590
.780
.890
.030
46.500
44
4
CCN II =76}
40
52
42
39
46
44
4
.358
.904
.590
.780
.890
."030
.500
.358
.904
0.860
1.920
1.970
0.730
2.170
1.530
0.607
0.640
1.550
1.600
0.520
1.720
1.206
0.516
1.
2.
1,
0.
3
1
1
0
0
0
0
1
0
0
,080
.580
.460
.340
.220
.736
.036
.480
.990
.820
.210
.500
.800
.442
3.944
7.113
5.061
1.741
10.181
5.608
2.870
2.372
3.952
3.385
1.154
6.428
3.458
1.764
1.078
2.106
1.402
0.428
2.897
1.582
0.851
0.600
1.071
0.887
0.279
. 1.691
0.906
0.476
67.678
82.455
70.084
106.556
104.166
86.188
16.456
69.341
82.841
70.877
107.447
106.063
87.314
16.554
187.934
212.506
180.628
153.271
185.847
184.037
18.905
187.934
212.506
180.628
153.271
184.564
183.780
18.888
1.
1
1
2
1
1
1
1
1
2
1
.507
.364
.819
.511
.486
.507
.526
.428
.714
.421
.459
Percent Reduction 21.176 53.917 38.337 42.759 -1.306 0.139
------- |