United States
Environmental Protection
Agency
Robert S Kerr Environmental Research EPA 600 2 79 151
Laboratory           August 1979
Ada OK 74820
Research and Development
Wastewater
Irrigation at
Tallahassee,  Florida

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                RESEARCH REPORTING SERIES

Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:

      1.  Environmental Health  Effects Research
      2.  Environmental Protection Technology
      3.  Ecological Research
      4.  Environmental Monitoring
      5.  Socioeconomic Environmental Studies
      6.  Scientific and Technical Assessment Reports (STAR)
      7  Interagency Energy-Environment  Research and Development
      8.  "Special" Reports
      9.  Miscellaneous Reports

This report has been assigned  to the  ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution-sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.

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                                             EPA-600/2-79-151
                                             August 1979
  WASTEWATER  IRRIGATION AT TALLAHASSEE, FLORIDA
                       by

                Allen R. Overman
              University of Florida
           Gainesville, Florida  32611
                 Project S800829
                 Project Officer

                 Lowell E. Leach
Robert S. Kerr Environmental Research Laboratory
      U.S. Environmental Protection Agency
              Ada, Oklahoma  74820
ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY
       OFFICE OF RESEARCH AND DEVELOPMENT
      U.S. ENVIRONMENTAL PROTECTION AGENCY
              ADA, OKLAHOMA  74820

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                                 DISCLAIMER


     This report has been reviewed by the Robert S.  Kerr Environmental
Research Laboratory, U.S. Environmental  Protection Agency, and approved for
publication.  Approval  does not signify that the contents necessarily reflect
the views and policies  of the U.S. Environmental Protection Agency, nor does
mention of trade names  or commercial  products constitute endorsement or
recommendation for use.
                                     11

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                                 FOREWORD


     The Environmental Protection Agency was established to coordinate
administration of the major Federal programs designed to protect the
quality of our environment.

     An important part of the agency's effort involves the search for
information about environmental problems, management techniques and new
technologies through which optimum use of the nation's land and water
resources can be assured and the threat pollution poses to the welfare of
the American people can be minimized.

     EPA's Office of Research and Development conducts this search through
a nationwide network of research facilities.

     As one of these facilities, the Robert S. Kerr Environmental Research
Laboratory is responsible for the management of programs to: (a) investi-
gate the nature, transport, fate and management of pollutants in ground-
water; (b) develop and demonstrate methods for treating wastewaters with
soil and other natural systems; (c) develop and demonstrate pollution
control technologies for irrigation return flows; (d) develop and demon-
strate pollution control technologies for animal  production wastes;
(e) develop and demonstrate technologies to prevent, control or abate
pollution from the petroleum refining and petrochemical industries; and
(f) develop and demonstrate technologies to manage pollution resulting from
combinations of industrial wastewaters or industrial/municipal  wastewaters.

     This report contributes to the knowledge essential if the EPA is to
meet the requirements of environmental laws that it establish and enforce
pollution control standards which are reasonable, cost effective and
provide adequate protection for the American public.
                    William C. Galegar
                    Director
                    Robert S. Kerr Environmental Research Laboratory

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                                  ABSTRACT


     Effluent from a secondary treatment plant was applied to crops on Lake-
land fine sand at Tallahassee, Florida.   Summer crops included coastal bermuda-
grass, sorghum x sudangrass, pearl  millet, corn and kenaf at irrigation rates
up to 200 millimeters (mm)/week [8 inches (in.)/week].   Winter crops included
rye and ryegrass at irrigation rates up  to 100 mm/week  (4 in./week).  Yields
and nutrient uptake increased with application rate,  while recovery efficiency
decreased.  Nitrogen recovery above 50%  required rates  in the range of 25-50
mm/week (1-2 in./week).

     Test wells in the 200 mm/week plots did show N03-N levels above 10 milli-
grams/liter (mg/1).  Results of this work and a companion study by the U.S.
Geological Survey showed mixing and dilution in the groundwater.   The soil  was
very effective in removing fecal  coliform bacteria and  BOD from the percolating
effluent.

     Field studies showed that nitrification was essentially complete in the
upper 120 centimeters (cm) [4 feet (ft)] of soil.   Phosphorus removal within
this same depth exceeded 99%, and complete removal  was  obtained before reach-
ing the water table some 12-15 meters  (m) (35-45 ft)  below ground surface.
Soil pH remained in the  vicinity  of 6.5.

     A model of cation transport  showed  that surface  exchange was linearly
coupled with flow velocity.   Good description of transport in a packed-bed
reactor was obtained for the NHt/K+ system.

     A model of phosphorus transport showed that at low velocities surface
exchange was diffusion limited, while  at higher velocities surface kinetics
was controlling.  The model  described  transport in a  packed-bed reactor quite
well.

     A model of phosphorus kinetics was  developed using Langmuir-Hinshelwood
kinetics for the heterogeneous process.   It also included a homogeneous
reaction.  Effects of pH and soil/solution ratio in a batch reactor were
accounted for.  The relevant species of  phosphate ion was identified as
H2PO~.

     This report was submitted in fulfillment of Grant  No. S800829 by the
University of Florida, Agricultural Engineering Department, under the sponsor-
ship of the U.S. Environmental Protection Agency.   This report covers the
period April 1, 1971, to December 1, 1978.
                                      IV

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                              CONTENTS
Foreword	    iii



Abstract	     iv



Figures	„  .     vi



Tables	„	   xiii



Acknowledgments   	     xx



   1.   Introduction  	      1



   2.   Conclusions 	      3



   3.   Recommendations	      4



   4.   Site Description	      5



   5.   System Characteristics  	     15



   6.   Crop Yields and Growth Response	     40



   7.  Analysis of Transport Processes 	  ....    143



References	    179



Appendix	    186

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                                   FIGURES



Number                                                                 Page



   1    General  Location of Study Site  	    6



   2   Detailed Location of Study Site 	  	    7



   3   Layout of Irrigation System and Field Plots 	    8



   4   Distribution of pH in Field Plots	   23



   5   Distribution of K in Field Plots	   24



   6   Distribution of Na in Field Plots	   25



   7   Distribution of Ca in Field Plots	   26



   8   Distribution of Mg in Field Plots	   27



   9   Distribution of Total Extractable Bases in Field Plots  ....   28



  10   Distribution of Extractable Bases in Field Plots  	   29



  11    Distribution of Base Exchange Fraction in Field Plots 	   30



  12   Distribution of Extractable P in Field Plots  	   33



  13   Distribution of Solution P Under Steady Irrigation  	   34



  14   Distribution of NH4~N and N03-N Under Steady Irrigation ....   35



  15   Estimated Yield Response of Coastal  Bermudagrass  	   43



  16   Estimated Nitrogen Recovery by Coastal Bermudagrass 	   44



  17   Estimated Phosphorus Recovery by Coastal  Bermudagrass 	   45



  18   Estimated Potassium Recovery by Coastal Bermudagrass  	   46



  19    Estimated Calcium Recovery by Coastal Bermudagrass  	   47



  20   Estimated Magnesium Recovery by Coastal Bermudagrass  	   48



  21    Estimated Sodium Recovery by Coastal Bermudagrass 	   49

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Number                                                                  Page
  22   Estimated Iron Recovery by Coastal Bermudagrass  	    50
  23   Estimated Zinc Recovery by Coastal Bermudagrass  	    51
  24   Estimated Yield Response of Sorghum x Sudangrass   	    53
  25   Estimated Nitrogen Recovery by Sorghum x Sudangrass  	    54
  26   Estimated Phosphorus Recovery by Sorghum x Sudangrass  	    55
  27   Estimated Potassium Recovery by Sorghum x Sudangrass   	    56
  28   Estimated Calcium Recovery by Sorghum x Sudangrass   ......    57
  29   Estimated Magnesium Recovery by Sorghum x Sudangrass   .....    58
  30   Estimated Sodium Recovery by Sorghum x Sudangrass  .......    59
  31   Estimated Iron Recovery by Sorghum x Sudangrass  	    60
  32   Estimated Zinc Recovery by Sorghum x Sudangrass  ,	    61
  33   Estimated Yield Response of Pearl Millet  	    62
  34   Estimated Nitrogen Recovery by Pearl Millet  .....  	    63
  35   Estimated Phosphorus Recovery by Pearl Millet  	  .    64
  36   Estimated Potassium Recovery by Pearl Millet   	    65
  37   Estimated Calcium Recovery by Pearl Millet   .  	    66
  38   Estimated Magnesium Recovery by Pearl Millet   	    67
  39   Estimated Sodium Recovery by Pearl Millet 	    68
  40   Estimated Iron Recovery by Pearl Millet	    69
  41   Estimated Zinc Recovery by Pearl Millet	    70
  42   Estimated Yield Response of Corn Silage .....  	    72
  43   Estimated Nitrogen Recovery by Corn Silage   	    73
  44   Estimated Phosphorus Recovery by Corn Silage   	    74
  45   Estimated Potassium Recovery by Corn Silage  	  ....    75
  46   Estimated Calcium Recovery by Corn Silage 	    76
                                    VII

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Number                                                                  Pa9e
  47   Estimated Magnesium Recovery by Corn Silage  	    77
  48   Estimated Sodium Recovery by Corn Silage   	    78
  49   Estimated Iron Recovery by Corn Silage	    79
  50   Estimated Zinc Recovery by Corn Silage	    80
  51   Estimated Yield Response by Corn Grain  	    81
  52   Estimated Nitrogen Recovery by Corn Grain  	    82
  53   Estimated Phosphorus Recovery by Corn Grain  	    83
  54   Estimated Potassium Recovery by Corn Grain   	    84
  55   Estimated Calcium Recovery by Corn Grain   	    85
  56   Estimated Magnesium Recovery by Corn Grain   	    86
  57   Estimated Sodium Recovery by Corn Grain 	    87
  58   Estimated Iron Recovery by Corn Grain	    88
  59   Estimated Zinc Recovery by Corn Grain	    89
  60   Estimated Yield Response o^ Kenaf 	    91
  61   Estimated Nitrogen Recovery by Kenaf  	    92
  62   Estimated Phosphorus Recovery by Kenaf  	    93
  63   Estimated Potassium Recovery by Kenaf 	    94
  64   Estimated Calcium Recovery by Kenaf 	    95
  65   Estimated Magnesium Recovery by Kenaf 	    96
  66   Estimated Sodium Recovery by Kenaf  	    97
  67   Estimated Iron Recovery by Kenaf	    98
  68   Estimated Zinc Recovery by Kenaf	    99
  69   Estimated Yield Response of Rye	100
  70   Estimated Nitrogen Recovery by Rye	101
  71   Estimated Phosphorus Recovery by Rye  	   102
                                    vi i i

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Number                                                                 Page

  72   Estimated Potassium Recovery by Rye 	   103

  73   Estimated Calcium Recovery by Rye	   104

  74   Estimated Magnesium Recovery by Rye 	   105

  75   Estimated Sodium Recovery by Rye	   106

  76   Estimated Iron Recovery by Rye	   107

  77   Estimated Zinc Recovery by Rye	,	   108

  78   Estimated Yield Response of Ryegrass  ,  .  ,	   109

  79   Estimated Nitrogen Recovery by Ryegrass  	   110

  80   Estimated Phosphorus Recovery by Ryegrass  	   Ill

  81   Estimated Potassium Recovery by Ryegrass	,  .  .  .   .   112

  82   Estimated Calcium Recovery by Ryegrass  .  ,  .  .  ,	   113

  83   Estimated Magnesium Recovery by Ryegrass	,  .  .  ,   ,   114

  84   Estimated Sodium Recovery by Ryegrass 	   115

  85   Estimated Iron Recovery by Ryegrass	,  ,   .   116

  86   Estimated Zinc Recovery by Ryegrass , .  .  ,	   117

  87   Response of Nitrogen Content, Dry Weight and Nitrogen
         Recovery for Corn (Pioneer 3369A) 	 ,.,..,.   122

  88   Response of Nitrogen Content, Dry Weight and Nitrogen
         Recovery for Corn (McNair 440V)	   127

  89   Response of Nitrogen Content, Dry Weight and Nitrogen
         Recovery for Sorghum x Sudangrass 	   131

  90   Response of Nitrogen Content, Dry Weight and Nitrogen
         Recovery for Kenaf	,	   135

  91   Growth Response of Cottonwood, Sycamore  and Black Locust
         to Effluent Irrigation  	   139

  92   Growth Response of Green Ash, Chinese Elm  and  Tulip Poplar
         to Effluent Irrigation  	   140

  93   Growth Response of Sweetgum, Bald Cypress  and  Red Cedar
         to Effluent Irrigation  	   141

                                     ix

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Number

  94   Growth Response of Loblolly Pine to Effluent
         Irrigation	142

  95   Steady State Distributions of Phosphorus for the
         Packed Bed Reactor	  147

  96   Dependence of Reaction,  Exchange and Dispersion
         Coefficients on Velocity for the Equilibrium
         Model  of Phosphorus  Transport	148

  97   Dependence of Adsorption,  Desorption and Reaction
         Coefficients on Velocity for the Kinetic Model  of
         Phosphorus Transport	,	154

  98   Effect of Soil Mass on Steady State Phosphorus
         Fixation in the Batch  Reactor	,	160

  99   Dependence on Maximum  Phosphorus Fixation  Rate
         on Soil Mass	,	161

 100   Dependence on Equilibrium  Constant of Phosphorus
         Fixation on Soil Mass	n^0
                                                                        I QL.
 101   Effect of pH on Steady State Phosphorus  Fixation
         in the Batch Reactor	164

 102   Dependence of Maximum  Phosphorus Fixation  Rate
         on pH	165

 103   Dependence of Equilibrium  Constant for Phosphorus
         Fixation on pH  . .  .  .  ,	166

 104   Effect of Solution Reaction on Steady State  Phosphorus
         Fixation in a Batch  Reactor	168

 105   Typical  Outflow Curves for NHl/K+ Transport  in a
         Packed Bed Reactor	172

 106   Dependence of Exchange and Dispersion Coefficients
         on Velocity for NH^/K+ Transport  	  174

 107   Lag  Between Surface and  Solution Concentration for
         NH^/K+ Transport  	  175

 108   Effect of Feed Concentration on Outflow  Curves
         for NHJ/K+ Transport  	  176

 109   Effect of Ionic  Strength on  Exchange Coefficient  and
         Cation Exchange Capacity for NH+/K+ Transport 	  177

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Number                                                                 Page

 A-l   Nitrogen Recovery by Sorghum x Sudangrass - 1971	   190

 A-2   Nitrogen Recovery by Kenaf - 1971	   196

 A-3   Nitrogen Recovery by Rye - 1971	   199

 A-4   Nitrogen Recovery by Ryegrass - 1971  	   201

 A-5   Nitrogen Recovery by Sorghum x Sudangrass With Single
         Applications - 1972	   204

 A-6   Nitrogen Recovery by Sorghum x Sudangrass With Split
         Applications - 1972	   212

 A-7   Nitrogen Recovery by Kenaf With Single
         Applications - 1972	215

 A-8   Nitrogen Recovery by Kenaf With Split
         Applications - 1972	218

 A-9   Nitrogen Recovery by Corn Grain With Single
         Applications - 1972	221

 A-10  Nitrogen Recovery by Corn Grain With Split
         Applications - 1972	224

 A-ll  Nitrogen Recovery by Corn Silage With Single
         Applications - 1972 ....".	"	227

 A-l2  Nitrogen Recovery by Corn Silage With Split
         Applications - 1972 .  . .  . ".	  230

 A-l3  Nitrogen Recovery by Pearl Millet - 1972	235

 A-14  Nitrogen Recovery by Rye - 1972	238

 A-l5  Nitrogen Recovery by Ryegrass - 1972	241

 A-l6  Nitrogen Recovery by Sorghum x Sudangrass - 1973	247

 A-l7  Nitrogen Recovery by Kenaf - 1973	250

 A-l8  Nitrogen Recovery by Pearl Millet - 1973	255

 A-19  Nitrogen Recovery by Corn Silage in 90 cm Rows - 1973 .....  258

 A-20  Nitrogen Recovery by Corn Silage in 45 cm Rows - 1973 	  261

 A-21  Nitrogen Recovery by Corn Grain in 90 cm Rows  - 1973  .....  264

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Number                                                                 Page



 A-22   Nitrogen Recovery by Rye - 1973	   272



 A-23   Nitrogen Recovery by Ryegrass  - 1973	   279



 A-24   Nitrogen Recovery by Pearl  Millet (Gahi-1)  - 1974  	   287



 A-25   Nitrogen Recovery by Pearl  Millet (Tiflate)  - 1974 	   290



 A-26   Nitrogen Recovery by Corn  Silage -  1974	   293



 A-27   Nitrogen Recovery by Coastal Bermudagrass  -  1974 	   299



 A-28   Nitrogen Recovery by Rye - 1974	   304



 A-29   Nitrogen Recovery by Ryegrass  - 1974	   309



 A-30   Nitrogen Recovery by Coastal Bermudagrass  -  1975 	   317
                                   xn

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                                   TABLES

Number                                                                 Page

   1    Conversions from Metric to English Units  	     2

   2   Lithologic Log of Calibration Well at the Treatment Plant ...    10

   3   Lithologic Log of Background Well	    13

   4   Characteristics of Lakeland Sand Near the Irrigation Site ...    14

   5   BOD and Solids Content of the Wastewater	    15

   6   Chemical Characteristics of the Secondary Effluent  	    17

   7   Chemical Characteristics of the Background Well  	    18

   8   Chemical Characteristics of the Field Well   	    18

   9   Chemical Characteristics of the Coastal  Bermudagrass Well  ...    19

  10   Average Chemical Characteristics of Effluent
         and Various Wells	    19

  11    Characteristics of Soil Extracts - March 1971	    21

  12   Characteristics of Soil Extracts - October 1971	    21

  13   Characteristics of Soil Extracts - March 1972	    22

  14   Extractable Bases 	    22

  15   Distribution of Basic Cations Between Adsorbed
         and Solution Phases	    31

  16   Climatological Data for Tallahassee - 1971   	    37

  17    Climatological Data for Tallahassee - 1972	    37

  18    Climatological Data for Tallahassee   1973	    38

  19    Climatological Data for Tallahassee - 1974	    38

  20    Climatological Data for Tallahassee - 1975	    39
                                    xm

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Number
  21   Climatological Data for Tallahassee - 1976	   39
  22   Crops Grown Under Effluent Irrigation at
         Tallahassee, Florida  	   40
  23   Crops and Varieties Used in Growth Study	119
  24   Irrigation Schedule for Growth Study  	  119
  25   Growth Response of Corn (Pioneer 3369A)  at 50 ran/week	120
  26   Growth Response of Corn (Pioneer 3369A)  at 100 mm/week  ....  120
  27   Growth Response of Corn (Pioneer 3369A)  at 150 mm/week  ....  121
  28   Growth Response of Corn (Pioneer 3369A)  at 200 mm/week  ....  121
  29   Estimated Yield and Nitrogen Response of Corn (Pioneer 3369A)
         at 50 and 200 mm/week	123
  30   Estimated Nitrogen Recovery by Corn (Pioneer 3369A)
         at 50 and 200 mm/week	123
  31   Growth Response of Corn (McNair 440V) at 50 mm/week	125
  32   Growth Response of Corn (McNair 440V) at 100 mm/week	125
  33   Growth Response of Corn (McNair 440V) at 150 mm/week	126
  34   Growth Response of Corn (McNair 440V) at 200 mm/week	126
  35   Estimated Yield and Nitrogen Response of Corn (McNair 440V)
         at 50 and 200 mm/week	128
  36   Estimated Nitrogen Recovery by Corn (McNair 440V)
         at 50 and 200 mm/week	128
  37   Growth Response of Sorghum x Sudangrass  at 50 mm/week .....  129
  38   Growth Response of Sorghum x Sudangrass  at 100 mm/week  ....  129
  39   Growth Response of Sorghum x Sudangrass  at 150 mm/week  ....  130
  40   Growth Response of Sorghum x Sudangrass  at 200 mm/week  ....  130
  41    Estimated  Yield and  Nitrogen Response of Sorghum x
         Sudangrass at 50  and  200 mm/week	132
  42    Estimated  Nitrogen  Recovery by Sorghum x Sudangrass
         at 50 and 200 mm/week	132
                                    xiv

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Number                                                                 Page

  43   Growth Response of Kenaf at 50 mm/week	  133

  44   Growth Response of Kenaf at TOO nun/week	133

  45   Growth Response of Kenaf at 150 mm/week	134

  46   Growth Response of Kenaf at 200 nun/week	134

  47   Estimated Yield and Nitrogen Response of Kenaf
         at 50 and 200 mm/week	136

  48   Estimated Nitrogen Recovery by Kenaf at 50 and 200 mm/week  ,  ,  136

  49   Estimated Harvest Age for Maximum Nitrogen Recovery 	  137

  50   Species in Tree Study	138

  51   Values of Rate Coefficients and Characteristic Times
         at 2 cm Depth	156

 A-l   Field Schedule for Summer 1971  .....  	  186

 A-2   Yield and Dry Matter of Sorghum x Sudangrass - 1971 	  .  187

 A-3   Nutrient Composition of Sorghum x Sudangrass - 1971 ......  188

 A-4   Nutrient Uptake by Sorghum x Sudangrass -  1971  	189

 A-5   Nutrient Recovery by Sorghum x Sudangrass  - 1971   .......  191

 A-6   Yield and Dry Matter of Kenaf - 1971  	,	192

 A-7   Nutrient Composition of Kenaf - 1971  	193

 A-8   Nutrient Uptake by Kenaf - 1971 .........  	  194

 A-9   Nutrient Recovery by Kenaf - 1971	195

A-10   Yield and Composition of Rye - 1971	196

A-ll   Nutrient Recovery by Rye - 1971 ................  198

A-12   Yield and Composition of Ryegrass -  1971  	200

A-l3   Nutrient Recovery by Ryegrass - 1971  	  ,,.,.,,.  200

A-14   Field Schedule for Summer 1972	  202

A-15   Schedule for Split Applications	203
                                     xv

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Number                                                                 Pa9e

 A-16  Yield and Dry Matter of Sorghum x Sudangrass with
         Single Applications - 1972	203

 A-17  Nutrient Composition of Sorghum x Sudangrass with
         Single Applications - 1972	205

 A-18  Nutrient Uptake by Sorghum x Sudangrass with
         Single Applications - 1972	206

 A-19  Nutrient Recovery by Sorghum x Sudangrass with
         Single Applications - 1972	207

 A-20  Yield and Dry Matter of Sorghum x Sudangrass with
         Single Applications - 1972	208

 A-21  Nutrient Composition of Sorghum x Sudangrass with
         Split Applications - 1972	209

 A-22  Nutrient Uptake by Sorghum x Sudangrass with
         Split Applications - 1972	210

 A-23  Nutrient Recovery by Sorghum x Sudangrass with
         Split Applications - 1972	211

 A-24  Yield and Composition of Kenaf with Single
         Applications - 1972	213

 A-25  Nutrient Recovery by Kenaf with Single
         Applications - 1972	214

 A-26  Yield and Composition of Kenaf with Split
         Applications - 1972	216

 A-27  Nutrient Recovery by Kenaf with Split
         Applications   1972	217

 A-28  Yield and Composition of Corn  Grain with Single
         Applications - 1972 	
                                           	219
 A-29  Nutrient Recovery by Corn  Grain with Single
         Applications - 1972	220

 A-30  Yield and Composition of Corn  Grain with Split
         Applications - 1972	222

 A-31   Nutrient Recovery by Corn  Grain with Split
         Applications - 1972	223

 A-32   Yield and Composition of Corn  Silage with Single
         Applications - 1972	225

                                     xv i

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Number                                                                 Page

 A-33  Nutrient Recovery by Corn Silage with Single
         Applications - 1972	  226

 A-34  Yield and Composition of Corn Silage with Split
         Applications - 1972	-	  228

 A-35  Nutrient Recovery by Corn Silage with Split
         Applications - 1972	  229

 A-36  Yield and Dry Matter of Pearl Millet - 1972	  231

 A-37  Nutrient Composition of Pearl Millet - 1972 	  232

 A-38  Nutrient Uptake by Pearl Millet - 1972	  233

 A-39  Nutrient Recovery by Pearl  Millet - 1972	  234

 A-40  Yield and Composition of Rye - 1972	  236

 A-41  Nutrient Recovery by Rye -  1972	  237

 A-42  Yield and Composition of Ryegrass	  239

 A-43  Nutrient Recovery by Ryegrass - 1972	  240

 A-44  Field Schedule for Summer 1973	  242

 A-45  Yield and Dry Matter of Sorghum x Sudangrass -  1973	  243

 A-46  Nutrient Composition of Sorghum x Sudangrass -  1973 	  244

 A-47  Nutrient Uptake by Sorghum  x Sudangrass - 1973   	  ...  245

 A-48  Nutrient Recovery by Sorghum x Sudangrass - 1973	  246

 A-49  Yield and Composition of Kenaf - 1973	  248

 A-50  Nutrient Recovery by Kenaf  - 1973	  249

 A-51  Yield and Dry Matter of Pearl Millet (Gahi-1) - 1973  	  251

 A-52  Nutrient Composition of Pearl Millet (Gahi-1) - 1973  	  252

 A-53  Nutrient Uptake by Pearl Millet (Gahi-1) -  1973 	  253

 A-54  Nutrient Recovery by Pearl  Millet (Gahi-1)  - 1973 	  254

 A-55  Yield and Composition of Corn Silage in 90  cm Rows  - 1973  ...  256

 A-56  Nutrient Recovery by Corn Silage in 90 cm Rows  - 1973 ....     257

                                    xvi i

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Number                                                                 Pa9e
 A-57  Yield and Composition of Corn Silage in 45 cm Rows - 1973 ...  259
 A-58  Nutrient Recovery by Corn Silage in 45 cm Rows - 1973	260
 A-59  Yield and Composition of Corn Grain in 90 cm Rows - 1973  ...  262
 A-60  Nutrient Recovery by Corn Grain in 90 cm Rows - 1973	263
 A-61  Field Schedule for Winter 1973	265
 A-62  Yield and Dry Matter of Rye - 1973	266
 A-63  Nutrient Content of Rye - 1973	267
 A-64  Nutrient Uptake of Rye - 1973	269
 A-65  Nutrient Recovery of Rye -  1973	271
 A-66  Yield and Dry Matter of Ryegrass  -  1973	273
 A-67  Nutrient Content of Ryegrass  -  1973	274
 A-68  Nutrient Uptake of Ryegrass -  1973	276
 A-69  Nutrient Recovery of Ryegrass  - 1973	278
 A-70  Field Schedule for Summer 1974	281
 A-71   Yield and  Dry Matter of  Pearl Millet  (Gahi-1)  - 1974	281
 A-72   Nutrient Composition  of  Pearl Millet  (Gahi-1)  - 1974  	  282
 A-73   Nutrient Uptake  of  Pearl  Millet (Gahi-1)  -  1974	284
 A-74   Nutrient Recovery by  Pearl Millet  (Gahi-1)  -  1974	,  .  286
 A-75   Yield and Composition of  Pearl Millet  (Tiflate)  -  1974   ....  288
 A-76   Nutrient Recovery by  Pearl Millet  (Tiflate)  -  1974   	  289
A-77   Yield and Composition of  Corn Silage -  1974	291
A-78   Nutrient Recovery by Corn Silage - 1974	,  292
A-79  Yield and Dry Matter of Coastal Bermudagrass  -  1974	294
A-80  Nutrient Content of Coastal  Bermudagrass  -  1974	295
A-81  Nutrient Uptake by Coastal Bermudagrass - 1974   	  297
                                  xvm

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Number                                                                  Page



 A-82  Nutrient Recovery by Coastal Bermudagrass - 1974 	  298



 A-83  Yield and Dry Matter of Rye - 1974	300



 A-84  Nutrient Content of Rye - 1974	301



 A-85  Nutrient Uptake of Rye - 1974	302



 A-86  Nutrient Recovery of Rye - 1974	303



 A-87  Yield and Dry Matter of Ryegrass - 1974	305



 A-88  Nutrient Content of Ryegrass - 1974	306



 A-89  Nutrient Uptake by Ryegrass - 1974	307



 A-90  Nutrient Recovery by Ryegrass - 1974	308



 A-91  Harvest Schedule for Summer 1975	310



 A-92  Yield and Dry Matter of Coastal Bermudagrass (Plots) - 1975  .  .  311



 A-93  Nutrient Content of Coastal Bermudagrass (Plots) - 1975  ....  312



 A-94  Nutrient Uptake by Coastal Bermudagrass (Plots) - 1975 	  314



 A-95  Nutrient Recovery by Coastal Bermudagrass (Plots) - 1975 ....  316



 A-96  Yield and Composition of Coastal Bermudagrass (Strip)   1975 .  .  318



 A-97  Nutrient Uptake by Coastal Bermudagrass (Strip) - 1975 	  319



 A-98  Nutrient Recovery by Coastal Bermudagrass (Strip) - 1975 ....  319
                                     xix

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                               ACKNOWLEDGMENTS


     Many persons contributed to the progress of this study.  Mr, Thomas P.
Smith, Director of Underground Utilities, City of Tallahassee, began the
effluent irrigation system at Tallahassee in 1966 and encouraged expanded
research on its performance, beginning in 1971.   He provided much support
for this work and stimulated a lot of discussion on the subject in Florida.
All of the field and laboratory measurements were conducted jointly with
Mr. William G. Leseman, Director, Tallahassee Water Quality Laboratory.  We
learned the art and science of waste treatment together.   Mr.  Alfred Nguy
served as laboratory assistant for the project and worked closely with
Mr. Leseman and his staff.

     Ms. Rolan Chu and Mr. Brian McMahon conducted the experiments and wrote
computer programs for the studies on rate processes.   The three of us, along
with Mr. Leseman and Mr.  Nguy, held many intensive discussions about chemical
kinetics and transport processes.

     Mr. Jack Woodard, Florida Department of Natural  Resources, Tallahassee,
provided assistance with  installation of test wells for the field study.

     Dr. Glenn W. Burton, Plant Geneticist,  Coastal Plains Experiment Station,
Tifton, Georgia, provided seeds for Tiflate  pearl  millet  and encouraged the
forage studies.

     Dr. Willis  Chapman,  Director of the University of Florida Agricultural
Research and Education Center, Quincy,  Florida,  kindly made a  forage harvester
and other equipment available on several  occasions.

     Mr.  Richard E.  Thomas served as initial  project officer and provided
stimulating discussions on land treatment of wastes.   Mr.  Lowell  E.  Leach
served in this capacity in the latter period and provided helpful suggestions
during the  completion  phase of the project.
                                    xx

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                                  SECTION 1

                                INTRODUCTION

     Land application systems for treatment of wastes have been in operation
for a long time at a large number of locations.  Several different techniques
(irrigation, recharge and overland flow) have been employed with a large
variety of wastes (agricultural, municipal and industrial).  A review of many
of the land application systems (both U.S. and foreign) has been given by
Stevens (1972).  Detailed reviews of facilities have been given also by
Sullivan et al_. (1973), Hartman (1975) and Carroll ejt al_. (1975).   Two munici-
pal systems which have received particular attention include Melbourne,
Australia (Seabrook, 1975 and Johnson e_t a]_., 1974) and Pennsylvania State
University (Kardos e_t al_., 1974 and Richenderfer et aj_., 1975).  In recent
years, a number of books have appeared on land treatment processes and systems
(Sopper and Kardos, 1973; Vesilind, 1975; Sanks and Asano, 1976; Shuval, 1976;
D'ltri, 1977; Elliot and Stevenson, 1977; and Loehr, 1977).  Survey of the
literature has been given by Tofflemire (1977) and by Carlisle and Stewart
(1977).

     Several other publications have appeared which aid in evaluation and
design of land treatment systems.  The U.S. Environmental Protection Agency
has published a design manual (USEPA, 1977) which outlines factors to consider
and procedures for design and evaluation.  Economic considerations have been
discussed by Young and Carlson (1974), Pound et_ al_. (1975) and Young (1976).

     The city of Tallahassee was probably the first city in Florida to utilize
wastewater irrigation.  During the 1940's, two treatment plants were con-
structed and subsequently discharged to a natural drainage stream and then
flowed to Lake Munson.  Much of the surface drainaqe also flowed through this
stream and lake.  In 1961, a 227 m3/day (0.060 mgd) high rate trickling filter
was constructed at the municipal airport.  Field tests at that site showed
that the soil could sustain an irrigation rate of 100 mm/day (4 in./day)
satisfactorily.  In 1966, a 9300 m-Vday (2.5 mgd) high rate trickling filter
was put into operation near the airport site, and included an irrigation
system with design capacity of 3700 m3/day (1 mgd).  The irrigation field of
6.5 ha (16 acres) was divided into four equal plots.  Experience showed that
these plots could handle 250 mm/day (10 in./day) over a four day rotation
without noticeable hydraulic problems.  Plots received maintenance mowing
without removal of vegetation.   The effects on groundwater quality were
unclear.

     An extensive study of geological and groundwater characteristics was
conducted in the vicinity of the irrigation site and surrounding area during
the period March 1972-June 1974 by the U.S. Geological Survey (Slack, 1975).

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Logs were made on 23 test wells,  along with hydrologic and chemical measure-
ments.

     This study was initiated in  1971  to evaluate the effects of wastewater
irrigation of a sandy soil  on 1)  growth and yields of forage crops, 2) changes
in soil and groundwater characteristics and 3)  coupling among transport
processes in the soil.   Both summer and winter  crops  were grown which were
suitable for production in the southeastern United States and for which
extensive literature was available.  Extensive  literature was also available
on the soil type (Lakeland fine sand)  prevalent at the treatment plant.

     For convenience, a table of  conversion factors from metric to English
units has been included (Table 1).
             TABLE 1.   CONVERSIONS FROM METRIC  TO  ENGLISH  UNITS
Metric Unit
Factor
                 English Unit
meters (m)
millimeters (mm)
hectare (ha)
kilogram (kg)
kilogram/hectare (kg/ha)
metric ton/hectare (mton/ha)
hectoliter/hectare (hl/ha)
meter3/minute  (m3/min)
meters/day (prr/day)
3.28
0.0394
2.
2,
 ,47
 .205
0.892
0.446
0.87
263
263 • 10
        -6
feet (ft)
inch (in)
acre (a)
pound (Ib)
pound/acre (Ib/a)
ton/acre (ton/a)
bushels/acre (bu/a)
gallons/minute (gpm)
million gallons/day (mgd)

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                                  SECTION 2

                                 CONCLUSIONS

     This study demonstrated the feasibility of growing both summer and
winter forage crops under effluent irrigation.

     Yields and nutrient contents compared favorably with values from the
literature.

     Yields and nutrient uptake increased with application rate, while
efficiency of nutrient recovery showed a decrease.  Nitrogen recovery above
50% required application rates of 25 to 50 mm/week (1 to 2 in./week).

     Soil pH remained around 6.5, in the optimum range for crop production.

     Lakeland fine sand was very effective in removing phosphate, BOD and
fecal coliform bacteria from the effluent.

     Shallow groundwater was influenced by effluent irrigation, but mixing
with groundwater caused dilution.

     Field measurements showed that nitrification essentially reached comple-
tion in the upper 120 cm (4 ft) of soil.

     The model of phosphorus transport showed coupling between  surface
exchange and convection.  Surface exchange was diffusion limited at the
lower flow rates.  Field and laboratory results correlated very closely.

     A model of phosphate kinetics based on Langmuir-Hinshelwood kinetics
described batch data very well.  Effects of soil/solution ratio and pH were
accounted for in this study.  The model included both heterogeneous catalysis
and a homogeneous reaction.

     The model of cation transport described data for NH^/K* system very
well.  Surface exchange was shown to be diffusion limited.

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                                  SECTION  3

                               RECOMMENDATIONS

     The feasibility of a  grazing  operation  coupled  with  effluent irrigation
should be investigated.  This  work showed  that  forage  production was reason-
able for green chop.

     Performance on poorly drained soil  should  be  studied,  with particular
reference to nitrogen behavior.   In this work appreciable nitrogen did reach
the groundwater.

     The relationship between  cation exchange capacity and  nitrogen uptake
should be established.

     Role of various factors on retention  and movement of pathogens in soils
receiving wastewater should be established.

     Determine breakdown and movement of carbon compounds in  soil  receiving
wastewater.

     A more  accurate measure of long-term  phosphorus fixing capacity of soils
is needed.

     A simplified model  of cation  transport  in  a mixed cation system should
be developed.

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                                  SECTION 4

                              SITE DESCRIPTION
LOCATION
     The study was a cooperative effort between the city of Tallahassee,
Fieri da and the Agricultural Engineering Department, University of Florida,
Gainesville.  All field studies were conducted in Tallahassee at the Thomas
P. Smith Wastewater Renovation Plant (formerly Southwest Sewage Treatment
Plant), located southwest of the city (Fig. 1) at the intersection of Spring
Hill Road and Capitol Circle (Fig. 2).

TREATMENT PLANT

     In 1966, the high-rate trickling filter was put on line with a flow of
950 m3/day (0.25 mgd).  By 1969 the flow had reached 3800 m3/day (1 mgd).
By October 1974 the Southwest Plant passed design capacity and reached 13000
m3/day (3.5 mgd), at which time the new 28,000 m3/day (7.5 mgd) conventional
activated sludge plant was opened.  The name of the plant was then officially
changed to Thomas P. Smith Wastewater Renovation Plant.  To accommodate the
steadily increasing flow, four large sprinklers were installed in a 7.3 ha
(18 acre) forest area to handle the flow above that needed for the agronomic
study.  This unit went into operation in March 1972.

IRRIGATION SYSTEM

     System layout was according to Figure 3.  A centrifugal pump with 2.7
m /min (720 gpm) capacity provided effluent from the polishing pond.   Irriga-
tion lines were portable aluminum with a 20-cm (8-in.)  main, 10-cm (4-in.)
laterals and 5-cm (2-in.) sublaterals.  Risers were 2.5-cm (1-in.) galvanized
pipe 3 m (10 ft) in height.  The impact sprinklers were Rainbird 70 with a
delivery rate of 0.21 m^/min (55 gpm) at 850 kg/cm^ (60 psi), which provided
an application rate of 1.25 cm/hr (0.5 in./hr).  Plots  were 30 m x 30 m (100
ft x 100 ft) with 40 m (120 ft) between plots to reduce spray drift.   Valves
were located on sublaterals to allow diverting of flow  among the various
plots.

CHARACTERISTICS

     The treatment plant was located adjacent to the Apalachicola National
Forest.  Hendry and Sproul  (1966) identified this area  as part of the Lake
Munson Hills, at the western edge of the Woodville Karst Plain.  Surface ele-
vation ranged 16-23 m (50-70 ft) above mean sea level,  water table elevation

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        TALLAHASSEE
Airport
                             Capitol   Circle
   Spring  Hill Rd
  Thomas  P Smith
Waste water Renovation
         Plant
         Figure 1.  General  location of study site.

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   Thomas R  Smith
Wastewater  Renovation
     Figure  2.  Detailed location of study site,

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0	
o	c
                        	
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ranged from 7-10 m (22-30 ft).  The top of the Floridan aquifer was 0-4 m (Slack,
1975).  A well, drilled at the site by the Florida Department of Natural  Resources
Bureau of Geology for calibration of equipment, provided a stratigraphic
profile of the geology (Table 2).  Core samples  from the background well
(Table 3) showed sand underlain by clay at 11.5-17 m with limestone below
17 m.  The water table depth was 13.5 m (45 ft)  below ground surface.   The
water table depth at the field well was 13 m (42 ft) below ground surface.
Soil samples collected prior to construction of the trickling filter showed
a pattern of 6-8 m (20-25 ft) of yellow quartz sand, a clay lens up to 3 m
(10 ft) in thickness, white quartz sand 3-4 m (10-12 ft) thick, then lime-
rock.  Vegetation in the area was mostly turkey oak and slash pine.  The soil
was Lakeland fine sand, a Quartzipsamment in the Entisol order.  A soil
profile taken near the treatment plant showed the soil contained approximately
95% sand, 2% silt and 3% clay (Table 4).  The pH of a 1:1 soil/water mixture
was approximately 5.5, and cation exchange capacity was very low.  Water
holding capacity of the soil was about 8 cm/m (1 in./ft).

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    TABLE 2.  LITHQLOGIC LOG OF CALIBRATION WELL AT THE TREATMENT PLANT


 Depth
                                   Description
m
  0-3        SAND, quartz, dark yellowish orange, fine to coarse, subangular-
            subrounded, loose, trace - 1% heavy minerals.

  3-4        SAND, as above, but very pale orange in color.

  4-9        SAND, quartz, grayish orange to dark yellowish orange, fine to
            coarse, mostly medium to coarse, loose, has burrowed or dis-
            rupted liminae appearance.

  9-10       SAND, quartz, very pale orange, fine to medium, some coarse,
            loose, trace - 1% heavy minerals.

 10-14       CLAY, mottled gray, light brown and dark yellowish orange, very
            sandy and silty at top - decreasing downward, soft but tough,
            waxy, abrupt contact with below.

 14-15       CAVITY

 15-17       CALCILUTITE, very pale orange, partially recrystallized, very
            finely sandy, soft but tough, microfossiliferous (Sorites,
            Miliolids).

 17-18       CAVITY

 18-18.5     CALCILUTITE, grayish orange,  partially recrystallized, hard,
            sandy.

 18.5-19     CAVITY

 19-20       CALCILUTITE, yellowish gray,  very clayey textured and soft,
            sandy.

 20-23       DOLOMITIZED CALCARENITE, pale orange,  very hard, partially
            recrystallized,  very microfossiliferous but indistinct.

23-26.5     CALCARENITE, pale  yellowish  orange, partially recrystallized,
            hard to  soft,  very microfossiliferous  with good porosity and
            permeability in  soft zones.

26.5-28     CAVITY -  filled  with rotten,  broken limestone material.


                                                       (continued)
                                    1,0

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                           TABLE  2.   (continued)
 DePth                                 Description
 28-39          CALCILUTITIC  CALCARENITE,  very pale orange, partially recrys-
               tallize-d,  very  microfossiliferous, soft, good porosity and
               permeability.

 39-40          CALCILUTITE,  very  pale  orange, partially recrystallized, hard,
               very  "tight"  -  silty  textured.

 40-46.5        CALCARENITE,  very  pale  orange, partially recrystallized, very
               microfossiliferous (first  appearance of Leps) moderately hard,
               very  porous and permeable,  appears to  have calcareous algae
               "globs"  -  especially  from  140-148 feet, macrofossiliferous
               molds.

 46.5-51.5     CALCILUTITE,  pale  yellowish  brown, partially recrystallized,
               very  evenly fine grained,  microfossiliferous (no Leps),
               friable,  partially dolomitized.  One inch base of interval
               appears  to be organic.

 51.5-59.5     DOLOMITE,  moderate yellowish brown, recrystallized, hard, some
               moldic  porosity, (with  some  zones silty textured and soft).

 59.5-60        CAVITY

 60-62          DOLOMITIC  CALCARENITE,  pale  yellowish  brown, very moldic, very
               microfosslliferous but  fossils indistinct, hard, brittle,
               recrystallized, grades  into  below.

 62-64.5        CALCILUTIC CALCARENITE,  grayish  orange, partially recrystal-
               lized,  microcoquina of  small  microfossils, porous and perme-
               able, friable.

 64.5-70        AS  ABOVE,  with  few macrofossils  fragments and molds and few
               zones of complete  recrystallization -  lower three feet pale
               yellowish  brown in color.

 70-71.5        CALCILUTITIC  CALCARENITE,  very pale orange, partially recrys-
               tallized,  microfossiliferous, soft to  medium hard, with
               harder  gray zones  (conglomeratic appearance).

 71.5-73        AS  ABOVE,  but more recrystallized and  harder - lower six
               inches  appears  dolomitized (small silt size rhombs) and
               laminated, and  is  pale  brown (?  organics) in color.
	. _                                                 ,   _	_	^

                                                       (continued)
                                    11

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                          TABLE  2.   (continued)
DePth                               Description
  m
73-73.5       DOLOMITE,  pale  brown,  crystalline,  very  hard, microfossilif-
              erous,  but very indistinct,  grades  into  below.

73.5-74       SAME AS 73-73.5.

74-74.5       SAME AS 73-73.5.

74.5-75       CAVITY.

75-76         DOLOMITE,  light brown,  crystalline  (sucrosic), with  zones  of
              non-crystalline,  partially recrystallized Calcarenite,  hard.

76-84         DOLOMITE,  as  73-73.5,  with some  zones  very micromoldic,  grades
              into below.

84-89         CALCARENITE,  very pale orange, soft to moderately  hard,
              partially  recrystallized, microfossiliferous, but  indistinct,
              intergranular and micromoldic porosity.

89-           CALCARENITE,  Pale yellowish  brown,  partially recrystallized,
              very microfossiliferous but  indistinct (many Leps),  hard,
              intergranular and micromoldic porosity but poorly  permeable.
Source:   Florida  Department  of  Natural Resources, Bureau of  Geology.
                                   12

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         TABLE 3.   LITHOLOGIC LOG OF BACKGROUND  WELL
  Depth                        n    ...
                               Description
0-0.3              Topsoil



0.3-1.5            Sand, dark yellow,  medium grain  size



1.5-3              Sand, light yellow, medium grain size



3-6                Sand, yellow,  medium grain size



6-7.5              Sand, light yellow, trace of  clay



7.5-9.5            Sand, very light yellow,  medium  grain



9.5-10             Sand, dark purple clay



10-10.5            Sand, gray, medium grain



10.5-11.5          Sand, white clay layers



11.5-13.5          Clay, gray, dense



13.5-15            Clay, dark yellow



15-16              Clay, deep yellow,  greenish gray streaks



16-17              Clay, lime rock fragments



17-18              Limestone, soft white



18-21              Limestone, dolomite, yellowish brown



21-24              Limestone, dolomite, tan
Source:   Florida Department of Natural  Resources,

         Bureau of Geology.
                             13

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                TABLE 4.  CHARACTERISTICS OF LAKELAND  SAND NEAR THE IRRIGATION SITE

Particle Si
Depth
cm
0-8
8-58
58-104
104-155
155-185
185-203

Horizon
Al
Cl
C2
C3
C4
C5
pH
H20
5.5
5.7
5.4
5.5
5.3
5.0
CEC
meq/100 gm
3.59
1.39
1.37
1.11
0.83
0.54

VC
0.7
1.0
1,2
1.5
1.4
1.5

C
21.2
21.6
21.6
20.3
21.1
22.4
Sand
M
48.7
48.7
47.2
43.5
44.1
46.0

F
21.9
22.5
23.8
28.9
26.7
26.2
ze Distribution

VF
1.7
1.5
1.7
2.3
2.0
1.8

Total
94.2
95.3
95.5
96.5
95.3
97.9
Silt

2.6
1.9
1.0
1.5
1.1
0.7
Clay

3.2
2.8
3.5
2.0
3.6
1,4
CEC = cation exchange capacity
VC = very coarse, 2-1 mm
C = coarse, 1-0.5 mm
M = medium, 0.5-0.25 mm
F = fine, 0.25-0.10 mm
VF = very fine, 0.10-0.05 mm
Silt = 0.05-0.002 mm
Clay = < 0.002 mm
Source:  University of Florida Soil Characterization Laboratory.

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                                  SECTION 5

                           SYSTEM CHARACTERISTICS
INTRODUCTION
     Data was collected on wastewater, groundwater and soil  to characterize
response of the system to wastewater irrigation.   Behavior of these three was
clearly interrelated.  Groundwater samples were collected for the highest
irrigation rates due to failure of the wells at the lower rates.   Climatic
data was included to show variability in temperature and rainfall.   There were
several nights during the winter season when irrigation would have  caused ice
formation.  However, this was only a minor problem.

WASTEWATER

     In September 1974 the activated sludge unit went on line.   Values  for BOD
and solids content (Table 5) for the period 4/71-9/74 were for the  trickling
filter and for 10/74-3/76 were for the activated  sludge plant.   Final BOD was


    	TABLE 5.  BOD AND SOLIDS CONTENT OF  THE WASTEWATER*	

                          BOD            Total Solids      Suspended Solids
      Period          Raw     Final       Raw     Final        Raw     Final
                          mg/1               mg/1                 mg/1
4/71-9/71
10/71-3/72
4/72-9/72
10/72-3/73
4/73-9/73
10/73-3/74
4/74-9/74
10/74-3/75
4/75-9/75
10/75-3/76
169
189
180
230
125
168
187
206
156
160
60
70
70
75
49
61
51
25
25
13
507
520
506
515
439
580
538
478
511
510
375
385
386
402
303
370
338
373
377
375
138
128
131
144
172
206
253
208
188
195
28
29
34
26
39
42
39
52
42
26
       Avg.            177       50         610       368         176       36
    *  From a  24-hour proportional  composite  sample  collected each week.
                                    15

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measured in samples from the outfall  of the polishing pond.   Suspended solids
averaged 36 mg/1, which represented 4 mtons/ha/yr (2 tons/acre/yr)  at 200 mm/
week.  Even this high rate did not cause noticeable clogging of the soil.
Chemical characteristics were measured on 24 hr proportional composite samples
collected at the pump intake (Table 6).  Average values obtained here agree
with those reported elsewhere (Kardos >e_t al_., 1974 and Metcalf and  Eddy, Inc.,
1972).

GROUNDWATER

     Background quality of groundwater in the vicinity of the treatment plant
was measured in a well near the power line (Figure 2).  Concentrations of
various chemical elements were very low (Table 7) and remained essentially
constant during the study period.   Chloride was approximately 2 mg/1, compared
to 50 mg/1 in the wastewater, and provided a good indicator for changes in
groundwater quality due to irrigation.

     The field well (Figure 3) showed the influence of irrigation (Table 8).
Application rates for that plot were 200 mm/week (8 in./week) during the
summer season and 100 mm/week (4 in./week) during the winter season.  Chloride
averaged 49 mg/1, compared to 51 mg/1 in the effluent.  A mass balance for chloride
showed the effluent comprised about 96% of the groundwater at this  well.
Total nitrogen averaged 18.6 mg/1, or 59% as much as in the effluent.  It
should be noted that nitrification (NH4 •* NOj) was essentially complete.
Potassium concentration dropped from 6.2 mg/1 in the effluent to 0.7 mg/1 in  the
well.  The decrease in nitrogen and potassium was attributable, in  part, to crop
uptake by the various crops grown on this plot.  Total phosphorus decreased
from 10.5 mg/1 in the effluent to 0.021 mg/1 in the groundwater; soil fixation of
phosphorus was complete.

     There appeared to be greater dilution of the percolating water with
groundwater in the well in the coastal bermuda (CB) plot (Table 9).  Chloride
in the well was 38 mg/1, or 75% of the value for effluent.  Based upon this
dilution factor, the concentration of total nitrogen in the percolating water
was 11.3/0.75 = 15 mg/1.  Since the effluent averaged 31.3 mg/1, this
represented a change of about 16 mg/1, or roughly 50%.  Since nitrogen
recovery by coastal bermudagrass at 200 mm/week (8 in./week) was less than
50%, some nitrogen appeared to be removed by other mechanisms.  From this
study it was not possible to discriminate among accumulation by roots, assim-
ilation by organisms, or reduction by organisms.  Average data for effluent
and the three wells were assembled for comparison (Table 10).  For all param-
eters the field and CB well values were intermediate to effluent and back-
ground levels.  Dilution was indicated by a comparison of the data  with data
from the USGS study (Slack, 1975).  Well 21, in the USGS study, was very near
the CB well and was cased to 75.3 m (247 ft).  During 1974, chloride averaged
16 mg/1 and total nitrogen 3.3 mq/1.

     Counts of fecal coliform, by the membrane method, never showed positive
counts, although the effluent was shown to contain as high as 10° fecal
coliform/100 ml.  BOD measurements showed values below 5 mg/1.  These results
indicated that the soil was very effective in removing bacteria and suspended
                                      16

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                 TABLE 6.   CHEMICAL CHARACTERISTICS  OF THE  SECONDARY  EFFLUENT

Characteristic
Peri od
1 C 1 1 WJ

4/71-9/71
10/71-3/72
4/72-9/72
10/72-3/73
4/73-9/73
10/73-3/74
4/74-9/74
10/74-3/75
4/75-9/75
10/75-3/76
4/76-9/76

pH

7.6
7.2
7.2
7.3
7.2
7.4
7.3
7.6
7.6
7.7
7.8

G
umho
460
520
530
530
410
480
480
440
400
420
440

Cl


61
60
74
51
47
40
42
43
44
44
N03
N

3.2
4.4
2.8
2.6
2.6
2.0
2.8
7.9
4.7
8.7
12.9
NH4 Kjeldahl
N

18.2
19.3
19.5
20.1
13.7
18.2
17.2
11.3
11.5
7.4
2.0
N

21.4
_
33.0
36.7
23.9
28.4
33.2
31.8
25.7
17.0
10.1
Total
N

24.6
_
35.8
39.3
26.5
30.4
36.0
40.8
30.5
25.7
23.0
Ortho
P
mg/1
6.5
7.1
_
8.5
7.1
9.0
9.0
7.7
7.7
8.2
8.4
Total
P


_
12.6
13,3
9.4
11.2
11.0
8.8
9.1
9.5
9.4

K


_
6.1
-
7.5
5.5
3.7
4.0
5.8
8.8
8.4

Ca


-
32
-
64
32
29
29
28
36
34

Mg


-
9.6
-
17.6
9.3
8.7
10.0
9.4
10.3
9.6

Na

_
-
39
-
55
36
33
26
33
41
42
Avg.      7.5    465    51    5.0   14.4   26.1      31.3      7.9      10.5     6.2    35    10.6    38

-------
                            TABLE  7.   CHEMICAL  CHARACTERISTICS OF THE BACKGROUND WELL*
OD
Period

3/73-9/73
10/73-3/74
4/74-9/74
10/74-3/75
4/75-9/75
10/75-3/76
4/76-9/76
Avg.
pH

7.8
8.1
8.3
8.4
8.3
8.5
8.4
8.3
G
umho
58
48
46
47
51
57
61
53
Characteristic
N03 NH4 Kjeldahl Total Ortho
Cl N N N N P

2 <
2 <
2 <
2 <
1 <
1 <
1 <
2 <

1 <1 1.0
1 <1 1.0
1 <1 1.2
1 <1 1.0
1 0.1 0.9
1 0.1 1.0
1 0.1 0.8
1 <1 1.0

<2
<2
<2
<2
<2
<2
<2
<2
mg/1

0.014
0.014
0.011
0.004
0.007
0.009
0.010
Total
P

0.030
0.025
0.037
0.022
0.011
0.015
0.025
0.024
K

0.3
0.2
0.1
0.1
0.4
0.2
0.3
0.2
Ca

10.5
6.2
7.6
8.4
8.6
8.5
10.5
8.6
Mg

0.5
0.5
0.6
1,0
1.5
1.2
0.6
0.8
Na

1.4
0.7
0,8
1.1
3.8
4.7
1.0
1.9

       From weekly  samples.
                               TABLE  8.   CHEMICAL  CHARACTERISTICS OF THE  FIELD WELL*

Period

4/73-9/73
10/73-3/74
4/74-9/74
10/74-3/75
4/75-9/75
10/75-3/76
4/76-9/76
Avg.
pH

7.5
7.5
7.7
7.9
7.7
7.9
7.8
7.7
G
umho
320
330
350
340
320
310
350
331
Cl

51
52
49
48
48
48
45
49
NO-, NH
N° N

16.4 <1
17.6 
-------
                   TABLE 9.   CHEMICAL CHARACTERISTICS  OF  THE  COASTAL  BERMUDA  WELL*

Characteristic
Period

10/74-3/75
4/75-9/75
10/75-3/76
4/76-9/76
Avg.
PH

8.1
8.1
8.1
8.2
8.1
G
umho
310
320
300
340
320
Cl

36
43
38
37
38
NO.
IT

9.8
11.9
9.2
8.7
9.9
NH4
N

1.6
0.3
0.5
0.4
0.7
Kjeldahl
N

1.8
1.1
1.4
1.2
1.4
Total
N

11.6
13.0
10.6
9.9
11.3
Ortho
P
mg/1
0.016
0.011
0.009
0.008
0.011
Total
P

0.030
0.025
0.017
0.020
0.023
K

0.7
1.0
0.5
0.7
0.7
Ca

40
33
36
43
38
Mg

6.8
5.2
5.4
6.5
6.0
Na

17
24
21
24
22

* From weekly samples.
              TABLE 10.  AVERAGE CHEMICAL CHARACTERISTICS  OF  EFFLUENT AND VARIOUS WELLS

Characteristic
Sample

Effluent
Background
Well
Field Well
CB Well
PH

7.5

8.3
7.7
8.1
G
umho
465

53
331
320
Cl

51

2
49
38
NOo
n

5.0

<1
17.3
9.9
NH4
N

14.4

< 1
<1
0.7
Kjeldahl
N

26.1

1.0
1.3
1.4
Total
N

31.3

<2.0
18.6
11.3
Ortho
P
mg/1
7.9

0.010
0.010
0.011
Total
P

10.5

0.024
0.021
0.023
K

6.2

0.2
0.7
0.7
Ca

35

9
35
38
Mg

10.6

0.8
4.1
6.0
Na

38

2
27
22

-------
organics.  Wells were always pumped a minimum of 2 min. before sample col-
lection to obtain a representative sample.

SOIL

     Soil samples were collected from several plots at various depths and at
different times to characterize some of the soil properties in relation to
chemical processes and crop production.  Since irrigation practices on the
plots were changed over the years from the beginning of plant operation in
1966, it was not possible to select plots which had received uniform treat-
ment.  Results are reported for the plots on which coastal bermudagrass was
sprigged in 1973.  The basic features of the system will be apparent from
the  results.

     Analyses were performed at the University of Florida Soil Testing Labora-
tory.  After air drying, samples were passed through a coarse sieve to remove
roots and other debris.  Soil pH was measured in a slurry of 50 g soil/100 ml
distilled water using a minimum equilibration period of 30 minutes.  Analyses
of pH, phosphorus and extractable bases (K, Ca, Mg, Na) were performed using
5 g  soil in 25 ml extractant of 0.7 N ammonium acetate in 0.54N acetic acid
buffered at pH 4.8.  A shaking time of 30 minutes was used.

     In 1971 and 1972 soil samples were collected at depth increments of 0-15
cm and 15-30 cm with an auger.  The need for more detail became apparent.  In
1973 samples were collected at depths of 15, 30, 60, 90 and 120 cm.  Soil was
removed with hole diggers to within 4 cm of the selected depth.  A sample
8 cm in length was then collected with a 5-crn diameter tube.

     High-rate irrigation experiments were conducted to measure distributions
of phosphate, ammonia and nitrate in the soil solution.  Attempts to collect
soil solution samples at irrigation rates up to 200 mm/week failed due to the
hydraulic characteristics of the sandy soil.  Samples were collected under
continuous irrigation.
     Results are given in Tables 11-13 and Figure 4.  These values were in
the same range as the value 6.4 reported by Fiskell  and Zelazny (1971) for
Lakeland soil.  Values of pH changed little or none  with depth.  Hortenstine
(1973) observed this same effect with effluent irrigation on Immokalee sand
at Walt Disney World in Florida.

Extractable Bases

     By leaching soil with a neutral  salt, such as ammonium acetate, it is
possible to determine the extractable (or exchangeable) basic cations (pri-
marily K,  Ca,  Mg, Na) held by the soil  (cf, Jacobs ejt aj_. , 1971).

     Results for this study are shown in Tables 11-14 and Figures  5-11.  A
noticeable change in the balances of cations occurred between the  sampling
dates  of 3/71, 10/71 and 3/72 (Tables 11-13); viz an increase in calcium
                                    20

-------
TABLE 11.  CHARACTERISTIC OF SOIL EXTRACTS  -  MARCH  1971.

Plot
1
2
3
4
Avg.
Depth
cm
0-15
15-30
0-15
15-30
0-15
15-30
0-15
15-30
0-15
15-30
PH
6.5
6.5
6.5
6.6
6.6
6.7
6.7
6.7
6.6
6.6
P
mg/kg
15.
7.
15.
8.
18.
10.
28.
19.
19.
11.
5
6
7
7
0
6
7
0
5
5
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
K
038
031
066
036
064
046
069
046
059
041

1
0
0
0
1
0
1
0
1
0
Ca
meq/100
.15
.55
.95
.53
.06
.65
.16
.75
.08
.62
Mg

0.56
0.43
0.55
0.47
0.56
0.45
0.61
0.51
0.57
0.47


0
0
0
0
0
0
0
0
0
0
Na

.69
.61
.60
.59
.60
.62
.60
.62
.63
.61


TABLE 12.
CHARACTERISTICS OF
SOIL
EXTRACTS

- OCTOBER
1971.



Plot
1
2
3
4
Avg.
Depth
cm
0-15
15-30
0-15
15-30
0-15
15-30
0-15
15-30
0-15
15-30
PH
6.5
6.5
6.8
6.8
6.5
6.7
6.6
6.6
6.6
6.6
P
mg/kg
17.
15.
19.
11.
16.
14.
16.
11.
17.
13.
1
3
2
7
7
1
8
3
4
1
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
K
038
020
054
041
028
020
049
026
041
026

2
1
1
0
1
0
1
0
1
1
Ca
meq/100
.12
.35
.58
.85
.52
.90
.48
.92
.68
.01
Mg
gin - -
0.41
0.36
0.44
0.26
0.30
0.24
0.42
0.26
0.39
0.28
_ _
0
0
0
0
0
0
0
0
0
0
Na
.41
.37
.39
.37
.39
.39
.39
.39
.40
.38
                           21

-------
TABLE 13.   CHARACTERISTICS  OF SOIL  EXTRACTS  -  MARCH  1972.
Plot
1
2
3
4
Avg.
Depth
cm
0-15
15-30
0-15
15-30
0-15
15-30
0-15
15-30
0-15
15-30
p
P mg/kg
6.9 17.1
6.9 18.1
6.9 16.4
6.9 16.3
6.9 15.3
7.0 17.8
6.9 22.8
6.9 19.8
6.9 17.9
6.9 18.0
K Ca Mg

0.013 1.70 0.38
0.015 1.62 0.39
0.038 1.55 0.31
0.031 1.50 0.36
0.010 1.38 0.36
0.010 1.45 0.34
0.015 1.80 0.39
0.008 1.30 0.34
0.020 1.60 0.36
0.015 1.47 0.35
Na

0.39
0.35
0.37
0.35
0.35
0.37
0.39
0.39
0.37
0.36

TABLE 14. EXTRACTABLE BASES

Plot
1
2
3
4
Avg.
Depth
cm
0-15
15-30
0-15
15-30
0-15
15-30
0-15
15-30
0-15
15-30
4/71

2.44
1.62
2.17
1.62
2.29
1.76
2.44
1.92
2.33
1.73
10/71 4/72
- - - lllcLj/ 1 UU y!ll bU ! 1 - - -
2.99 2.48
2.10 2.37
2.46 2.27
1.52 2.24
2.25 2.09
1.55 2.17
2.33 2.60
1.60 2.04
2.51 2.36
1.69 2.21
Avg.
2.63
2.03
2.30
1.79
2.21
1.83
2.46
1.85
2.40
1.88
                          22

-------
             PLOT
I
I—
O.

O
                fill    f    I     I
           (!)     1
           D     2
           4—4-	till!
     Figure 4,  Distribution of pH 1n field plots,
                          23

-------
 0
            1     I  —I     I     I     I
Figure 5.   Distribution of K in field plots,
                   24

-------
   en'
o

 fi.

I—
CL

Q
                  ,   MEO/100 GM
             f    i   Y    i
                                   PLOT
          \     \     I     I     \     \     I
    Figure 6,  Dtstrtbutlon of Na 1n field plots,
                    25

-------
              Cfi,  MEO/100  GM
   o
   tf>"~
«LJ


 »
I
I—

CL
   g.
   O*
   o
   Al-
   O
   un-
4—1   -\	f
4—+
    Figure 7.  Distributton of Ca tn field plots,
                     26

-------
              .   MEQ/1QO  GH
Figure 8,  Distribution of Mg in field plots.
                 27

-------
  EXTRflCTHBLE BflSES,  HEO/100  GM
  o. „
    """
CJ

 fr

I—
Q_

Q
   P. .
   o
                              PLOT
O    1
D    2
A    3
 Figure 9, Distribution of total extractable bases
         1n field plots.
                   28

-------
        >  [
      <*>
ELEHEMT
 O    K
      Nfi
                                   D
                                        MG
o
    Figure  10.   Distribution of extractable bases
                in  field plots.
                     29

-------
                             FRfiCTION,  %
CJ
   10-
                                   75

00
 Figure 11.  Distribution of base exchange  fraction
           in field plots.
                      30

-------
with a corresponding decrease in the others.  The quantity of extractable
bases remained essentially constant with time (Table 14), but showed a
decrease from 2.40 at 0-15 cm to 1.88 at 15-30 cm.

     In 1973, soil samples were collected from five depths.  Potassium and
sodium showed little change with depth (Figures 5 and 6), while calcium and
magnesium showed strong decreases with depth  (Figures 7 and 8).  These values
are in the same range reported by Fiskell and Zelazny (1971) for Lakeland
soil.  The sum of extractable bases.decreased with depth (Figure 9).  The same
trend was reported by Fiskell and Zelazny (1971) for Lakeland and by Horten-
stine (1973) for Immokalee soil.  Greater weathering and higher organic matter
near the soil surface cause this distribution.  Values for the four plots were
averaged for each depth to obtain average base cation concentrations.  Values
were then averaged for each cation from the four plots and divided by the
average base concentration to determine base exchange fraction.  Results are
shown in Figure 10 for the four cations.  More than one-half the base exchange
was occupied by calcium.  Most soils are dominated by calcium (Jacobs et a1.,
1971; Buckman and Brady, 1969; Fiskell and Zelazny, 1971; and HortenstTne,
1973).  Potassium occupied less than 5% of base exchange, due to the fact
that the fraction of potassium in the effluent was very low (less than 5%).

     The calcium fraction decreased with depth, from 70% at 15 cm to 54% at
120 cm (Figure 11).  Sodium showed a corresponding increase from 15% at 15 cm
to 30% at 120 cm.  It can be shown that for a mixed cation system (monovalent
and divalent cations) that as total cation exchange capacity decreases the
balance of adsorbed cations will shift toward monovalents and away from diva-
lents.  This agrees with the increase of sodium with depth and the compli-
mentary decrease of calcium, induced by the decrease of base exchange with
depth.

     The distribution of basic cations between adsorbed and solution phases
are shown in Table 15 for the 15 cm depth.  Overman and West (1972) showed


              TABLE 15.  DISTRIBUTION OF BASIC CATIONS BETWEEN
   	ADSORBED AND SOLUTION PHASES.	


    Cation                         K          Ca         Mg         Na
Adsorbed,
Solution,
Adsorbed
meq/100 gm
meq/1

0
0
3R
.036
.16

1
1
176
.66
.60

0
0
71
.33
.79

0
1
36
.36
.70

that Lakeland fine sand drained to a water content of approximately 10% under
gravity drainage.  Assuming a bulk density of 1.70 g/cm3,  the distribution
ratio for potassium was calculated to be:


                                     31

-------
    K Adsorbed    0.036 meg  (1.70)g      cm3     103cm3      1         ,R
    K Solution "    100 mg       cm3    (Oj0)crr)3    1     (0.16)meq "  JB


Solution values were assumed to be the.same as in the  effluent.   Even  though
the exchange capacity of the soil  was low, the reserve  of adsorbed cations was
appreciable.

Phosphorus

     Values for ammonium acetate - extractable phosphorus (Tables 11-13 and
Figure 12) showed a strong decrease with depth in all  cases.   This decrease
in weakly bound phosphorus with depth resulted from the logarithmic' decay in
solution P concentration with depth due to phosphorus  fixation by the  soil
(Overman ejt al_.,  1976).  A plot was irrigated with effluent continuously for
three days in July, 1970, and soil solution samples were collected at  the end of
that period.  Measurements of orthophosphate showed a  decrease from approxi-
mately 10 mg/1 P in the effluent to 0.1 mg/1 P at 120  cm (Figure 13),  for a
removal of 99%.  Hortenstine (1973) observed this same decay on  Immokalee
sand receiving effluent.   Phosphorus fixation in these Florida acid soils was
associated with oxides  of iron and aluminum.  Hortenstine (1973) demonstrated
that addition of lime to the soil enhanced fixation.  Hook e^t a]_. (1973)
reported rapid fixation of phosphorus by a clay loam soil in the Pennsylvania
State University studies.  More than 90% of the phosphorus in the effluent was
removed in the upper 15 cm of soil.

Nitrogen

     The soil solution  samples collected for phosphate analysis  from the
three-day continuous irrigation were also analyzed for NH*-N and NOq-N.
Ammonia concentration showed a rapid decrease with depth (Figure 14),  and
appeared to follow first order kinetics.  Nitrate concentration  showed a
corresponding increase  with depth.  These measurements indicated a high level
of activity by nitrifying organisms in the soil, since nitrification was
essentially complete in the upper 90 cm.

CLIMATE

     Temperature and rainfall data were taken from National Oceanic and
Atmospheric Administration records at the Tallahassee  Municipal  Airport
located approximately 3 km (2 mi.) from the treatment plant (Tables 15-20).
The transition from cool to warm season occurred during March-April, while
the reverse transition  occurred during October.  Accordingly, summer crops
were planted around April 1 and winter crops were planted in October.   While
the average minimum temperature was above freezing for all months, the number
of days with freezing temperatures ranged from 21 in, the 1971-1972 winter sea-
son to 50 in the 1975-1976 winter season.  Daytime temperatures  were always
above freezing.  June-September represented the period of high stress  for
crop growth due to high daytime temperatures.  Rainfall was extremely vari-
able during the period  1971-1976, with an average value of 179 cm (71  in.)
and a range of 148-223  cm (58-88 in.).  The least monthly rainfall was 1.40
cm (0.55 in.) in April  1972, while the greatest monthly value was 44.52 cm

                                     32

-------
               P,   MC/KC
          1     i     !    i     'f
Figure 12.  Distribution of extractable P  in
          field plots.
                  33

-------
o
    Figure  13.  Distribution of solution P
               under steady irrigation.
                        34

-------
   o. „
     ^
CJ
O
   Q= _
   o
    o
        NHi
            i      I     8     g     I      S      I
     Figure 14,  Distribution of NH4-N  and  N03-
                 under steady irrigation
                          35

-------
(17.5 in.)  in July 1975.   The  greatest  amount  in a  single day was 14.73 cm
(5.8 in.) in June 1975.   Runoff was  not a  problem due  to the high permeability
of the sandy soil.  Frequent afternoon  showers  during  June-August did present
some difficulty with harvests.   In spite of  rainfall and sizable irrigation
levels, summer crops did  show  moisture  stress  at times due to the low water-
holding capacity of the soil.
                                     36

-------
       TABLE 16.  CLIMATOLOGICAL DATA FOR TALLAHASSEE - 1971*

Temperature, °C
Year

1971











Number
Month

Jan
Feb
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
of days

Max
27
27
28
31
33
37
35
34
34
34
30
29
Ava
Max
18
19
21
26
29
33
32
32
32
29
23
23
with freezing -

Avg
11
12
13
17
21
26
26
27
26
22
14
17
39
Avg
Min
3
4
4
8
13
19
21
21
20
15
6
11


Min
-12
-10
-5
-2
1
14
19
19
12
5
-3
-1

Rain

Total
7.72
13.92
12.23
4.70
10.36
18.90
27.43
27.31
3.99
8.79
2.24
10.44

, cm
Greatest
Day
3.38
5.72
3.33
1.85
3.78
5.26
8.53
4.39
1.73
5.84
1.19
4.65


* Source:  National Atmospheric and Oceanic Administration.
       TABLE 17.  CLIMATOLOGICAL DATA FOR TALLAHASSEE - 1972*

Temperature, °C
Year
Month
Avg
Max Max
1972











Number
Jan
Feb
Mar
Apr
May
June
July
Auq
Sept
Oct
Nov
Dec
of days
28
27
29
33
32
37
36
38
36
32
30
27
with freezi
21
18
24
28
29
32
33
34
33
28
21
21
ng -
Avg
15
12
16
20
23
26
27
28
26
21
15
14
23
Avg
Min
9
6
7
12
17
19
21
22
19
14
9
7


Min
-4
-6
-1
3
8
9
16
19
16
6
-4
-3

Rain

Total
16.56
17.91
14.73
1 .40
23.06
28.27
10.49
13.28
0.28
4,45
25.04
12.32

, cm
Greatest
Day
3.73
4.57
6.63
0.66
10.01
14,73
3.35
4.04
0.15
2.95
10.59
7.75


* Source:  National Atmospheric and Oceanic Administration.
                                 37

-------
       TABLE 18.  CLIMATOLOGICAL DATA FOR TALLAHASSEE - 1973*

Temperature, °C
Year Month

1973 Jan
Feb
Mar
Aor
May
June
July
Aug
Sept
Oct
Nov
Dec
Number of days

Max
27
24
29
30
35
35
35
35
34
32
29
26
Avg
Max
18
18
24
25
29
32
34
33
32
29
25
19
with freezing -

Avg
11
11
18
18
22
27
28
27
27
21
18
11
32
Avg
Min
4
3
12
11
16
21
23
22
22
13
11
3


Min
-8
-8
0
1
4
19
20
17
18
-1
-1
-8

Rain

Total
12.60
18.19
34.47
33.35
21.29
18.01
11.20
27.38
13.46
5.97
8.15
18.95

, cm
Greatest
Day
3.07
7.65
8.74
11.86
7.62
4.22
2,21
4.37
4.29
3.12
4.95
4.62


* Source:  National Atmospheric and Oceanic Administration.
       TABLE 19.  CLIMATOLOGICAL DATA FOR TALLAHASSEE- 1974*

Temperature, °C
Year
Month
Avq
Max Max
1974











Number
Jan
Feb
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
of days
27
26
31
29
34
34
35
34
34
30
29
27
with freezi
24
20
26
26
31
32
33
32
31
27
22
18
ng -
Avg
19
12
18
18
24
26
27
27
26
18
14
11
31
Avg
Min
14
4
11
11
17
19
21
22
21
10
6
4


Min
6
-8
2
1
8
14
16
21
12
5
-4
-7

Rain

Total
8.53
7.29
7.62
10.13
21.82
9.75
19.30
23.83
26.49
2.36
4.17
9.65

, cm
Greatest
Day
3.15
4.24
3.35
5.46
8.79
3.23
4.39
7.75
9.07
2.36
2.03
3.76


* Source:   National  Atmospheric and Oceanic Administration.
                                 38

-------
        TABLE 20.   CLIMATOLOGICAL  DATA FOR TALLAHASSEE  -  1975*

Temperature, °C
Year
Month
Avg
Max Max
1975











Number
Jan
Feb
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
of days
27
27
28
33
36
34
34
36
34
31
29
26
with freezi
19
21
22
26
31
32
31
33
30
27
23
18
ng -
Avg
13
14
16
19
24
27
26
27
25
21
16
11
38
Avg
Min
6
7
9
11
18
21
22
22
19
15
8
3


Min
-4
-6
-1
0
14
17
17
21
10
4
-3
-6

Rain

Total
29.67
7.24
15.70
18.21
26.26
12.12
44.52
17.27
12.40
11.20
3.81
19.89

, cm
Greatest
Day
8.28
2.72
8.51
7.52
4.70
5.46
11.61
4.83
5.49
8.15
2.51
8.92


   Source:   National  Atmospheric and Oceanic  Administration.
       TABLE 21.  CLIMATOLOGICAL DATA FOR TALLAHASSEE - 1976*

Temperature, °C
Year Month

1976











Number of

Jan
Feb
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
days with
Max
24
28
29
33
31
36
38
36
34
31
25
25
freezi
Avq
Max
17
23
24
28
29
31
34
33
31
24
19
17
ng -

Avg
8
14
17
19
22
26
28
28
25
17
12
10
48
Avq
Min
1
5
10
11
16
20
22
22
19
11
5
3


Min
-9
-7
0
3
8
16
20
19
13
2
-6
-7

Rain

Total
14.05
3.07
13.46
4.19
29.62
27.99
10.64
18.67
7.09
29.95
26.52
10.39

, cm
Greatest
Day
6.71
2.01
5.38
1.70
7.67
6.65
3.10
5.72
3.45
9.27
12.53
2.34


*Source:  National Atmospheric and Oceanic Administration.
                                  39

-------
                                  SECTION 6

                       CROP YIELDS AND GROWTH RESPONSE
 INTRODUCTION
     These studies focused on agronomic field crops; viz, forage and grain
crops.  Crops grown are listed in Table 22.  Corn was grown for both silage
and grain.  All of these (except kenaf) are grown extensively in the United
States, so that considerable experience is already available on their produc-
tion and utilization.  Also, data on growth and nutrient uotake is available
from the literature, providing comparison between response to fertilization
and response to effluent irrigation.

     Limited studies were conducted on several species of trees to determine
the response to effluent irrigation on well-drained soil.


              TABLE 22.  CROPS GROWN UNDER EFFLUENT IRRIGATION
     _ AT TALLAHASSEE, FLORIDA


         Common Name _ Scientific Name _

                                Summer Crops

      Coastal bermudagrass                Cynodon dactylLon  (L.)
      Pearl millet                        Pe.nvuA£tim typhA
                                            Staph and E. C. Hubbasid
      Sorghum x sudangrass                Sorghum vulgate P&IA. x
      Corn                                Zea Mat/4 L.
      Kenaf                               Ht/b-c6coi eannab.-cna6 L.

                                Winter Crops
      Rye
      Ryegrass                            LolMm
     Effluent irrigation should be viewed in two ways:  1) wastewater renova-
tion and 2) crop production.  Viewed by the first, the nutrients of concern
are nitrogen and phosphorus; by the second, major (N, P, K), minor (Ca, Mg,
etc.) and micro (Fe, Zn, Cu, etc.) elements are all important.  For example,

                                     40

-------
removal of nitrogen from the wastewater by the crop depends upon crop vigor,
which depends upon other elements (such as K).  For this reason, wastewater
and plant samples were analyzed for a variety of elements other than N and P.

     Application levels of an element were estimated from average effluent
concentration for the crop season, irrigation rate and irrigation period.
The formula used was

                                A = 0.01 CIT

where  A = nutrient applied, kg/ha
       C = concentration in effluent, mg/1
       I = irrigation rate, mm/week
       T = irrigation period, weeks

To aid in conversion between English and metric units, a table of conversion
factors (Table 1) has been included in this report.  For example, 1  kg/ha  =
0.892 Ib/acre; a value in Ib/acre is 0.892 times the value in  kg/ha.

     Crop uptake of an element was estimated by

                                 H = 0.1 YDN

where  H = nutrient harvested, kg/ha
       Y = green yield, metric tons/ha
       D = dry matter, %
       N = nutrient composition, %

     Crop recovery of an element was calculated from the definition  of simple
recovery as


                                 R = j x 100


where R is recovery efficiency in %.  It should be noted that  some investi-
gators correct H for background uptake where no nutrient is applied,
reflecting base fertility of the soil.  For Lakeland fine sand base  fertility
is low, so that simple recovery is adequate.  The significance of recovery
efficiency should be properly understood -- it indicates that capacity of the
crop to capture the particular element under the prevailing environmental
conditions, and reflects crop/soil/environmental interactions.  It does not
provide a mass balance for the element, since no indication of storage (roots,
soil, organisms), leaching to groundwater, or gaseous losses are provided.

     Net values for dry matter content and nutrient content were calculated
as weighted averages by the formula

                                     N
                             V    =  I  V  W /W
                              avg        n  n
                                    n=l
                                     41

-------
where  Vavq = weighted average value, %

       Vn   = value for nth harvest, %
       Wn   = dry weight for nth harvest, mton/ha

       W    = total dry weight for all harvests, mton/ha

CROP YIELDS AND NUTRIENT RECOVERY

     Results are presented in this section on crop production under waste-
water  irrigation on Lakeland fine sand.  Measurements were made of green
weight, dry matter composition and nutrient composition for the various field
crops.  Estimates were then made of dry yields, nutrient uptake and recovery
efficiencies.  The approach was to use several crops under various irrigation
rates  to identify suitable crops and to bracket the loading rates.  It is
important  in fertility studies to have enough treatment levels (minimum of
three) to  be able to estimate the response curve, either yield vs rate or
nutrient vs rate.  Such curves approximate a curve of diminishing returns,
exhibiting an asymptotic approach to a maximum.  Data presented here follows
that general trend.

     Availability of equipment and personnel for the project favored treatment
levels over replication.  All harvesting operations utilized an available
commercial forage harvester (rather than a plot harvester) with a work force
of  no  more than two persons.  In most cases, four irrigation rates were used.
Irrigation sprinklers were located on 30 m x 30 m (100 ft x 100 ft) spacing.
Irrigation intensity was 13 mm/hr (0.50 in./hr).

     Throughout the experiments no commercial fertilizer, herbicides or
pesticides were used.  Limited cultivation of crops was practiced for weed
control.   In some cases, weed infestation did present a problem.

     In this section summaries of yield, nutrient uptake and nutrient recovery
are presented for the crops listed in Table 22.  These response curves were
estimated  for each crop from the basic data compiled in Appendix A,  In
Appendix A data are presented by years due to commonality of effluent charac-
teristics  and cultural practices.  In this report mton is used to denote
metric tons, to minimize confusion.   Cultural practices and analytical pro-
cedures are included in Appendix A,  also.

Coastal Bermudagrass

     Estimates of yields and nutrient uptake for coastal bermudagrass are
shown in Figures 15-23.  All  of the  curves exhibit the asymptotic response
which is typical of fertility studies.  Dry matter content averaged about 28%
in the green forage.   Values for dry matter yield (Figure 15) agreed closely
with fertility studies by Burton ejt  aj_. (1963).  Estimates of N uptake
(Figure 16) also increased with application as reported by Burton et al.
(1963), showing close agreement at lower rates and slightly below their values
at higher application rates.   It should be noted that application rates were
for the growing season (approximately 6 months) rather than for the year.
Recovery  efficiency followed  a  curve of diminshing returns,  dropping from 85%


                                     42

-------
CE
X
O
yj
o
GC
cc
>_
cc
        Figure 15.  Estimated yield response of coastal  bermudagrass,

-------
cr o
o
LU
*:
CT
H	1	1	h	1	h-	1	1	h
H	h
                                 f
             ^00      $00       1200      1600
               N  flPPLICflTION,   KG/Hfl
                                                     o
                                                     •o
                                               QZ

                                           . .p >


                                               UJ
                                                    -MC
                                          2000
   Figure 16.  Estimated nitrogen recovery by coastal bermudagrass.

-------
X
o
   g-
 «

LU o
         -I	1	1	1	1	1	1	1
                                            UPTflKE
                                            RECOVERY
         -I	1	1	h-	1	h	S
              100       200       30©       100

               P  RPPLICfiTIGN,   KG/Hfl
                                                      ,o
                                                       00
                                                      •S
                                                      .o >
                                                       » O
                                                         o
                                                    soo
  Figure 17.  Estimated phosphorus recovery by coastal bermudagrass.

-------
-pi
cr>
                                                                      O
                              SO    "    120   "    180

                                K  flPPLICflTION,  KG/Hfl
300
                    Figure 18.  Estimated potassium recovery by coastal bermudagrass.

-------
CC


o
   O.
   <£>
a:
i—
a.
CE
O
     o
                   ^	1-
                         -i	1	1-
                                                      _o
                                            RECOVERY
              -h-	1	h	1	h	1	1	f-
300       SOO       900       S 200

 Cfl  flPPLICflTION,  KC/Hfl
                                                         CC
                                                         LU
                                                     4.0 >

                                                         CJ
                                                      o
                                                    isoo
    Figure 19.  Estimated calcium recovery by coastal  bermudagrass.

-------
OD
                   o, „
                     *~
                O
o S--
                         ^	1	1—h—i—h-—i
                                                           RECOVERY
             100       200      300       100


              MG  RPPLICflTION,  KG/Hfl
                                                      .0

                                                      3"
                                                                        CC

                                                                        UJ

                                                                     I o >

                                                                      "M O



                                                                        UJ
                                                                    500
                   Figure 20,  Estimated magnesium recovery by coastal bermudagrass.

-------
oc

^
o
cc
I—
cs_
              H	1	!	1	1-—I	1	\-
                                            ECDVERY
+
                                                        or
                                                        UJ
         UJ



         
-------
                  a:
                  x

                  o
                   •h

                  LU
en

O
                                4-	1	H-—|
               1-	S-
                                                               RIECOVERY
                           4	-f
+
+
+
4»	1-
+
                                5         JO        35        30

                                FE  flPPLICflTIGN,  KG/Hfl
                               o
                               •o
                                    ,ltf» «^»
                                    ir*. &3
                                       ec
                                       UJ

                                   J_o >
                                   "*"iui o

                                       O
                                       yj

                                   •f   flC




                                   -4C f
                      Figure 22.  Estimated iron recovery by coastal  berrnudagrass.

-------
   8
   T&m, „
o
UJ IP.

cc
     0
                   4-	h
                                           UPTflKE
                                           RECOVERY
                                 +-	1
                                                      .o
                                                        o:
                                                        yj
                                                        >
                                                        o
                                                        4J
                                                        LLJ
                                                        OC
                                                    10
              ZN  RPPLICflTION,  KG/Hfl
      Figure 23.  Estimated zinc recovery by coastgl bermudagrass.

-------
at 200 kg/ha to 60% at 400 kg/ha.   The response curve of P (Figure 17)  also
showed asymptotic response.  These values agreed closely with those of Adams
ejt al_. (1967).  Although P recovery by the crop was low, losses of P were
minimal since this soil had a high capacity to retain P (Overman, et al..
(1976).  Results indicated that coastal bermudagrass showed strong response
to K (Figure 18).  For application rates below 200 kg/ha, K uptake exceeded
application, suggesting possible need for supplemental K.  Results from fer-
tility studies (Adams ejb al., 1967 and Woodhouse, 1968) agreed with these
estimates, and also showecTuptake in excess of application.

     Uptake of other elements by coastal bermudagrass is shown in Figures 19-
23.  These may aid in estimating the mineral  and trace element composition
of the forage for animal feed.

     Under conditions of adequate moisture and nutrients, coastal bermuda-
grass should be harvested 5 or 6 times during the warm season.  From Figure
15, for an N application of 400 kg/ha (360 Ib/acre) the estimated yield of
dry forage was 10 mtons/ha (4.5 tons/acre).  For hav production (65% dry
matter) this represented 15 mtons/ha (7.0 tons/acre), while greenchop (28%
dry matter) was 36 mtons/ha (16 tons/acre).

Sorghum x Sudangrass

     A strong response to nutrient application occurred for sorghum x sudan-
grass (Figures 24-32).  The yield curve (Figure 24) agreed fairly closely with
fertility studies in Gainesville,  Florida, with this variety (Agronomy Mimeo
Report, 1971), where 228 kg/ha applied N produced 9.3 mton/ha of dry forage.
Nitrogen content (approximately 1.75%) agreed with the range of values from
experiments in Alabama (Hoveland et al., 1967), and were somewhat below the
2.5% from Reulke and Prine (1974)  in Florida using more frequent harvest than
in the present study.

     Uptake of K by sorghum x sudangrass (Figure 27) exceeded application
below 120 kg/ha.  This indicated potential K deficiency with effluent irri-
gation and possible need for supplemental K.   Other elements were supplied in
adequate quantities 'since recoveries were below 100% (Figures 28-32).

     With adequate moisture and nutrients, sorghum x sudangrass should be
harvested about 3 times during the season.  Estimated yields of dry forage
from Figure 24 were 10 mtons/ha (4.5 tons/acre) at 400 kg/ha (360 Ib/acre)
applied N.  Corresponding yields of green chop (19% dry matter) were 53 mtons/
ha (23 tons'/acre).

Pearl Millet

     Pearl Millet showed a strong response to applications of nutrients
(Figures 33-41).  Estimated yields (Figure 33) agreed well with those from
Florida (Agronomy Mimeo Report, 1971) and from Georgia (Hart and Burton,
1965.)  Nitrogen uptake rose rapidly with increases in applied N (Figure
34), while recovery dropped sharply from approximately 50% at 200 kg/ha of N.
These values of uptake by pearl millet were somewhat below those of Hart and
Burton (1965), primarily due  to a  harvest frequency of roughly 8 weeks in the

                                     52

-------
                            ^—i—i—i
Ol
CO
                   cc
i|00      800       1200
 Ml flPPLICflTION,  KG/Hfl
                                                                      2000
                        Figure 24,  Estimated yield response of sorghum x sudangrass.

-------
en
                 CE ©
                 o
                 cc
                 ^_

                 Q-
-I	fc
                                          i     S
-S	h—+
HOO   "    800       1200     -1600


  N  RPPLICfiTION,  KG/Hfl
                                                              RECOVERY
                                                              4—+
                                          ,o
                                          'CD
                                                                       -t.°  ^s
                                                                       ""*Bf'J,r.«^  **•*
                                             CC

                                             yj

                                          ,o >
                                          is- 0

                                             o
                                             yj
                                                                      2000
                     Figure 25,  Estimated nitrogen recovery by sorghum x sudangrass.

-------
                   O
                   O-
en
                cr
                3:
                o
                 *
                UJ o.
4—rH	1	h	1	h	1	1
                         +—s-—lisa
                              ISO       300       5150   "    600
                               P  RPPLICflTION,   KG/Hfl
                                                            RECOVERY
                                   g    S
                                                0=
                                            J_G >
                                                O
                                            •f   fiE

                                              . a,
                                           750
                   Figure 26,  Estimated phosphorus recovery By sorghum x sudangrass.

-------
en
01
                              @D        120       ISO       Z>10

                               K  flPPLECflTIGN,  KG/Hfi
                    Figure 27.  Estimated potassium recovery by sorghum x sudangrass,

-------
en
                             (100      300      1200      1600
                             Cfl  RPPLICflTION,  KG/Hfl
aooo
                     Figure 28.  Estimated calcium recovery by sorghum x sudangrass.

-------
                    o
en
co
                                                 f-—I	1—I-
 .0
                              100       200       500       100

                              MG  flPPLICflTION,  KG/Hfl
500
                      Figure 29.  Estimated magnesium recovery by sorghum x sudangrass.

-------
                                                   f-	1	h—4-
en
UD
                 o
                 is:
                               500       1000      1500

                                    fiPPLICfiTION,
                      Figure 30,  Estimated sodium recovery by sorghum x sudangrass,

-------
         5        10        15        £0
        FE  RPPLICflTION,  KG/Hfl
Figure 31.  Estimated iron recovery by sorghum x sudangrass.

-------
en
                         i     g     i    \
                                                          RECOVERY
                                       8        sa       i@
                             ZN  flPPLICfiTION,  KG/Hft
                                                                   - -Brt  K|
•o
                     Figure 32.  Estimated zinc recovery by sorghum x sudangrass.

-------
2
O
o
CE
u.
CE
O
                            »    I     I     I
                       4-	1    I    I
             1100       800      iaOO      1600

              N  fiPPLICRTION,  KG/Hfl
2000
       Figure 33.  Estimated yield response of pearl millet.

-------
en
OJ
                   o
                   o
                 LU S.
                 i£ 01
                 CE
                 J—
                 o.
H	h—H	h	1-
-I	h	1-
      !     I
                                                  4-
                                         .0
                                         "at
                                                                       -8
                                            a=
                                            UJ
                                         .0 >
                                          3- CD
                                            O
                                            yj
                                         •  CC
                                                                      _ .o
WG       800      1200

  N  fiPPLICRTION,  KG/Hfl
                                                                     2000
                        Figure 34.  Estimated nitrogen recovery by pearl  millet.

-------
CTi
-p.
                   o
                   o
                a:
                x JC
                x
                o
LU o. _
                                      -I	—h	1"
                                                                        01

                                                                        lU

                                                                      .0 >
                                                            RECOVERY
                                   ^—i—i
                              100       200       300

                               P  flPPLICflTIQN,  KG/Hfl
                                                    500
                      Figure 35.  Estimated phosphorus recovery by pearl millet.

-------
O1
en
                             10       90       120   "    ISO

                               K  flPPLICfiTION,  KG/Hfl
200
                      Figure 36.  Estimated potassium recovery by pearl millet.

-------
CTl
CTl
o


 *
LU oj.

a:
i—
a.
                          •*	!	f-
                                      H	f—+
                                   H	h
                                                            UPTflKE
                                                                     _ .o ..
                                                                     -^ffli s+i
                                                                         ac
                                                                         yj
                                                                      .0 >
                                                                       fw o

                                                                         O
                                                                         LsJ
                                                            RECOVERY
             300   "    800       300       1200

              Cfl  RPPLICfiTIGN,  KG/Hfl
                                                                    ssoo
                       Figure 37.  Estimated calcium recovery by pearl millet.

-------
cr>
o
o-
                CE o
                O
                     i
4—H	h-	h
                                                                       o
                                                                      •o
                                                                       IfM
                                                   o
                                                   -in
                                                             ECOVERY
                                                                      o >
                                                                      •o
                                                                      .2 o
                                                                         o
                                                                      _o
                                                                      iin
                                                  •f
           100       200       300       100

           HG  fiPPLICfiTION,  KG/HR
                                                   •o
                                      soo
                      Figure 38.  Estimated magnesium recovery by pearl millet.

-------
00
CE


X

O
CE
I—

O.
                       H	S	h
                                                           I    I
                                                           UPTflKE
                                                                       cc
                                                                        o
                                                                        o
                                                                        CE
                                                           RECOVERY
                                   4-
                                4-	1-
                                                iaoo

                              Nfl flPPLICflTION,  KG/Hfl
                                                  aooo
                       Figure 39.  Estimated sodium recovery by pearl millet.

-------
CTl
LD
                 X
                 o
a.



LU
                                                I	h	1
                                                                  OVERY
                                     B     I     I
                                *         10        IS

                                    RPPLICflT
                                         I     I-
                                             20
                                                                           S ^?
    flc
    UJ

^g
    O
    laj
r  ec

   t yj
 o
                      Figure 40,   Estimated  iron  recovery fay pearl millet,

-------
o
cz
l__
a,
                                 I    i     8
                                           ECDVERY
^ — s- — i
i
                                     \     \
              a        '4        e         s
             ZN  flPPLZCfiTIGN,  KG/Hfl
                                                    o
                          01
                          UJ
                        0 >
                        - o
                          o
                          IUJ
                       +  «QC
                       io
         Figure 41.  Estimated zinc recovery by pearl millet.

-------
Georgia experiments.  The nitrogen content of forages generally decreases
with age, so that harvesting more frequently may increase total N uptake.

     Particular attention should be called to K uptake (Figure 36).  It was
estimated that pearl millet had a large capacity to recover K, and at low
application rates exhibited some deficiency.  Supplemental K could be bene-
ficial in this range.  Effluent appears to supply other elements in sufficient
quantities (Figures 37-41) since recoveries were below 100%.

     With adequate moisture and nutrients pearl millet should be harvested
3 or 4 times during the growing season.  At 400 kg/ha (360 Ib/acre) applied N,
forage yield of 10 mton/ha (4.5 tons/acre) was estimated (Figure 23).  The
corresponding yield of greenchop (17% dry matter) was 59 mtons/ha (26 tons/
acre).

Corn Silage

     Dry yields and N uptake (Figures 42 and 43) from this study agreed with
results from Alexander et al.  (1963), but were somewhat below those of Robert-
son et_ aJL (1965) and Gonske and Keeney (1969).  Uptake of N by corn is-more
efficient in bands than in broadcast application, as in effluent irrigation.
Crop uptake estimates of P, K, Ca and Mg (Figures 44-46) agreed closely with
those of Alexander et_ aj_. (1963).  Estimates of Fe and Zn concentrations
(Figures 49 and 50) of 0.020% and 0.0050%, respectively, were in the range of
other results (Linsner, 1970).  All the elements were adequate (Figures 42-
50), except K.

     Since corn silage has a short growing season (10-14 weeks), it could be
followed with another summer crop (such as soybeans).

     Estimated forage yield at 200 kg/ha (180 Ib/acre) applied N were 5 mtons/
ha (2.2 tons/acre), from Figure 42.  The corresponding yield of greenchop
(20% dry matter) was 25 mtons/ha (11  tons/acre).

Corn Grain

     Estimated yields of corn grain are given in Figure 51.   These values
agreed closely with those of Stanley and Rhoads (1971) in Florida and Jung
e_t aj_. (1972) in Wisconsin.  Nitrogen uptake estimates (Figure 52) from this
study were below those of Jung _et aj_. (1972), for two reasons.  First,  the
Wisconsin soil had a slightly higher base fertility than the Florida soil.
Second, corn intercepts more of the nitrogen banded application than for
broadcast, as in effluent irrigation.  This same effect was  noted above for
corn silage.

     Estimates of other elements are given in Figures 53-59.  Other nutrients
appeared to be present in adequate quantities.  However, at 25 mm/week corn
ears did not fill out completely in the 1973 season, indicating possible K
deficiency under extended production of corn at low application rates.   Sup-
plemental K might be necessary under these conditions.
                                     71

-------
CT

I
o
o
cc

-------
0
200      100      ©00       ©00
  N  flPPLICflTION,  KG/Hfl
   Figure 43.  Estimated nitrogen recovery fay corn silage.

-------
         -I	h—H	h-—I	h-	1-
X
o
LU O.

CE
i—
a.  •


a- S-
                                                     _ .o
                                                     ^^tf>
                                                     ..o >
                                                         yj
                                                         oc
                                                      _o
                                             E-CEIVERY
                   1-
                             -I	h
              50       100       ISO       200

               P flPPLICflTIGN,   KG/Hfl
                                                     2SO
       Figure 44,   Estimated phosphorus recovery by corn silage.

-------
   S
o
UJ O,
V S1

CC
j__

Q_  •
         ^	h
4—H	h	1	I-
                                            ECOVERt
                             i    I
              i|0        80       tao       160

               K  flPPLICflTIONf  KG/Hfl
                                                      o
                                                      o
                                                      fM
                                                      O
                                                      o >

                                                      2 o
                                                     .O
                                                   200
      Figure 45.  Estimated photassium recovery by corn silage.

-------
CTl
               o
Q-
ID

cr S
         •4-	h-	h
-I	1	1	1	J-
                                                          UPTflKE
                                                                   -•»
                                                          RECOVERY
                                                -I
             300       600       300      1200

              Cfl  flPPLICflTIGN,  KG/Hfl
                                                                     *>
                                                                       cc
                                                                       yj
                                                                       >
                                                                       o
                                                                       o
                                                                  1SOO
                      Figure 46.  Estimated calcium recovery by corn silage.

-------
CT _

X
o

 *
LU O.

CE
I—

ID

O £
  ^—h—\—h—h
                                             .0  >
                                             "OB  o
                                                o
                                               o
      I
                I     I
                               300       100
             MG  flPPLICflTION,  KG/Hfi
500
Figure 47.  Estimated magnesium recovery by corn silage.

-------
CO
                O
cc
H—
a.
3


CT
                            300      @00       900      1200

                             Nfl  flPPLICflTEON,  KG/Hfl
                                                 1500
                       Figure 48,  Estimated sodium recovery by corn silage.

-------
         +-T-H	1	1-	1	1-	1	1	1
o
   5?._
 _o
  CM
                                           RECOVERY
                                                     _JA
    CC
    UJ
. .0 >
  - o
    o
    UJ
-f-  cc

    UJ
•f-BA U_
         -S	h—H	h-—h-—+—I	h-—I-
 •o
              6        12        18

              FE  RPPLICflTION,   KG/Hfl
30
         Figure 49,  Estimated iron recovery by corn silage.

-------
CD

O
? *
X *
o


 *
oj ej_

cc
I—
a.  T
         ^—h—i—i—i—-+
^	\-
                                                                    _o
                                                                     ru
                                                          UPTflKE
                                                                   . .o
                                                                       CC

                                                                       LU
                                                                       LU

                                                                       fiC
                                                                   - HM>
                                                          RECOVERY
                                       h	1	h
                              2         «         6         8

                             ZN  flPPLICfiTION,  KG/Hfi
                                                   10
                                                     •o
                       Figure 50.  Estimated zinc recovery by corn silage.

-------
               * O.
              CL
              IT
co
                   o
                                                   H	1-	\-
                                     •h—f-
100      200      300       &IOO
 N flPPLICflTIGN,  KG/Hfl
SOO
                      Figure 51.  Estimated yield response by corn grain.

-------
00
ro
                O
                cc
o. .
irt-8-
                                                       OJ

                                                    .0 >


                                                       o
                                                       yj
                                                    •   cc
                                                             RECOVERY
       I     I
                              300   "    600   "   900

                                N  flPPLICfiTION,
4—+
                                                                       -o
                                                  1500
                       Figure 52,  Estimated nitrogen recovery by corn grain.

-------
CO
00
o


 A
yj


                         -i	h
                                                                     •§
                                                                       oc
                                                                       UJ
                                                                     .o >
                                                                     SF o
                                                                       O
                                                                       yj
              50        100       ISO

               P  flPPLICflTION,  KG/Hfl
                                                                   2SO
                       Figure 53.  Estimated phosphorus recovery by corn grain.

-------
CO
                X
                o
                CE
                h-»
                CL.
                         4	h—f
               4	h	1	h-	h
                              h	1-	1-
                             UPTfiKE
                                          


                                          UJ
50    "   100       ISO       200
  K  flPPLICflTION,  KG/Hfl
                                                           RECOVERY
                             4—4
                                                                   250
                       Figure 54,  Estimated potassium recovery by corn grain.

-------
00
en
cc


o
                     0
                                   H	h	1	1-
                                                           UPTflKE
                                                                        cc
                                                                        UJ
                                                                        >

                                                                        o
                                                           RECOVERt
         -I—I-
             300
                                                     +
    600       800      1200

flPPLICfiTION,  KG/Hfi
isoo
                       Figure 55,  Estimated calcium recovery by corn grain,

-------
00
                X
                yj oJL
                    0
                         I     i
i     I
                                                          UPTRKE
                           CC
                           yj
                           >
                           o
                           o
                           yj
                           O
                                                          RECOVERY
                             4,
III!
SOO      200

HG  flPPLICflTION,  KG/Hfl
                      500
                       Figure 56.  Estimated magnesium recovery by corn grain.

-------
co
en

x
o
cr
i—
o_


a: £+
                                       •{	1	h
                                                          UPTflKE
                             H	1	1	\-
                             300       eoo      soo       1200

                             Nfl  fiPPLICflTION,  KG/Hfl
                                                          RECOVERY
                                          -h—I-
                                                                       CC
                                                                       UJ
                                                                       >
                                                                       o
                                                                       C_)
                                                                       UJ

                       Figure 57.  Estimated sodium recovery by corn grain.

-------
CO
CO
               CE
               l_

               £L
               LU
               LL.
                                     S2       S8

                            FE  flPPLICflTION,  KG/Hfl
                      Figure 58.  Estimated iron recovery by corn grain.

-------
00
UD
                      .
                    fu
                 a:

                 x   •
                 o
                   *

                 LU
-1	h
                                      I     I
                                ZN  FtPPLICfiT
                                                                 ECOVERY
                               f     I
                                                   tr:
                                                                             yj
                                                                         10
                         Figure 59.  Estimated zinc recovery by corn grain.

-------
     For N application of 200 kg/ha (180 Ib/acre),  the yield of dry corn was
8 mtons/ha (3.6 tons/acre), from Figure 51.   For a  moisture content of 15%,
this corresponded to 9.4 mtons/ha (150 bu/acre).

Kenaf

     Dry matter yields of kenaf showed weak  coupling with application rate
(Figure 60).   Estimates based on the present study  were below those of Pepper
and Prine (1969), but in both cases only one harvest was obtained with Ever-
glades 41 variety.  Killinger (1967) reported similar yields to those of
Pepper and Prine (1969) with this variety.   The study of Killinger (1967)
showed a nitrogen content of 2.0% at 123 kg/ha applied N, compared to an
estimated value of 1% or less at that rate for this study.   Apparently N up-
take by kenaf was much weaker under broadcast application than banded appli-
cation, as used by Killinger (1967).  This probably accounted for low recovery
efficiencies  (Figure 61) estimated from the  present work.  As with other
crops, K uptake exceeded application at lower rates (Figure 63),  indicating
a possible need for supplemental  K.  Karbassi  and Killinger (1966) showed a
positive response of kenaf to K addition.  Kenaf also showed high demand for
Fe (Figure 67).  All elements, except K, were supplied in adequate quantities
(Figures 60-68).

     A yield  of 6 mtons/ha (2.7 tons/acre) of dry forage was estimated at
250 kg/ha (220 Ib/acre) of applied N (Figure 60).   This corresponded to 33
mtons/ha (15  tons/acre) of greenchop at 18%  dry matter.

Rye
     Dry matter yield showed an appreciable  increase  with  application rate
(Figure 69).   These estimates of yield agreed  closely with results  of Morris
and Jackson (1959)  and Morris and Reese (1962)  in  Georgia.  Nitrogen  uptake
(Figure 70) also agrees closely with  values  from Parks et_ _al_.  (1970).   As
with several  of the summer crops, at  lower application rates,  rye shows K
uptake exceeding application (Figure  72).  This  indicates  potential  K defi-
ciency and need for supplemental  K.   Other elements  appear to  be supplied  in
adequate quantities (Figures 70-77).   Beneficial  effects of the trace elements
Fe and Zn (Figures  76 and 77) occur,  since appreciable fractions of these  are
taken up by the rye.

     With adequate  moisture and nutrients, rye  should be harvested  about 3
times.  Since the yield of dry forage at 160 kg/ha (140 Ib/acre) applied N
was 3.5 mtons/ha (1.6 tons/acre)  from Figure 69,  the  corresponding  yield of
greenchop (20% dry  matter) was 18 mtons/ha (7.8 tons/acre).

Ryegrass

     Estimates of dry matter yields  (Figure  78)  agreed closely with results
from Mislevy and Dantzman (1974)  in  Florida.  Uptake  of N  (Figure 79) also
agreed with Mislevy and Dantzman (1974).  Nitrogen content of  2.5 to  3.5% is
in the range given  by Hylton ejt al_.  (1965),  and showed an  increase  with
application rate.  Content of other  nutrients  estimated here were:   P = 0.75,
K = 1.5, Ca = 0.5 and Mg = 0.25%.  Values  reported for these elements by

                                     90

-------
CE

X
z
LU
O
CE
cc
QC
Q
             a§0       SOO       750      I

              N  flPPLICfiTION,  KG/Hfl
        Figure 60.  Estimated yield response of kenaf.

-------
    250      500      750      JOOD
      N  RPPLICfiTIOM,  KG/Hfl
1250
Figure 61.  Estimated nitrogen recovery by kenaf.

-------
              ^ - f» -
                               1 - 1
X £


o




 A

LU c


CE








a, SH-
     0
                                    Rl
 -I	h-—I-	h—H	h-—I	h
      @0       160       240       320

        P fiPPUCfiTIGN,  KG/Hfl
                                                 flC

                                                 LU

                                              .0 >
                                              W o

                                                 o

                                                 LU
Figure 62.  Estimated phosphorus recovery by kenaf.

-------
   &
   g
a.  • •
                     +•—f—+
                                       RECOVERY
                120      160

K  RPPLICflTIQN,  KG/Hfl
                                                 O
                                                 o
                                                   cc
                                                   o
                                                   LLJ
                                               200
      Figure 63.  Estimated potassium recovery by kenaf.

-------
cn
                            200      HOO      ©00      800
                            Cfl  fiPPLICFSTION,  KG/Hfl
                       Figure 64.  Estimated calcium recovery by kenaf.

-------
LD
CTl
                            60       120      ISO      210
                            MG  flPPLICflTION,  KG/Hfl
300
                       Figure 65.  Estimated magnesium recovery by kenaf.

-------
©_
a:

x
o
           I     S
  0
       -I—h
4—4	\—4	h
                                                          --40  .X
                                               RECOVERY
                            I      I      I  —I	-+
               250        SCO        750        1000
                                                               o
                                                               o
      Figure 66.  Estimated sodium recovery by kenaf.

-------
UD
cx>
                                     §        9        12

                           FE  fiPPLICftTlON,  KG/Hfi
                      Figure 67.  Estimated iron recovery by kenaf.

-------
X
o
Qu  "f
s     s
B     8
                                         •i    S
                                UPTRKE
                                                  4-  >-
                                                      01
                                                      UJ
                                                  __o >

                                                      4J
                                                      yj
                                          RECOVERY
                                                   •o
                                         S
             ZN  fiPPLICflTION,   KG/Hfl
        Figure 68.  Estimated zinc recovery by kenaf.

-------
o
o
              
-------
   o
   o-
   
-------
o
cc o


o

 «
UJ o.

cr
H.
a.  •


Q. S'
                                                           UPTRKE
         +-—I-—f
                                                 I    1     B     I
T'(*» «^

     «
    >-
    (DC


 •° >
    O

 -   cc

 _ Q.
                                       130       180
                               P  flPPLICflTION,  KG/Hfi
                                                   300
                         Figure 71.  Estimated phosphorus recovery by rye.

-------
o
CO
                   o
                   o-
SCr
                    o
H	h
4-—I	h—h
                                                  O
                                                 -o
                                                          UPTflKE
                                                                    o
                                                                    -O
                                                                    O
                                                                       yj

                                                                   1-   cc


                                                                    O ^
                                                          RECOVERY
                                                     •f
           30        ©0   "    90    "   120

            K  flPPLICRTION,  KG/Hfl
                                          150
                        Figure 72.  Estimated potassium recovery by rye.

-------
o
-pa
                  0
ISO       320       i|80       PIG

Cfl  flPPLICRTIQN,  KG/Hfi
                       Figure 73.  Estimated calcium recovery by rye.

-------
o
Ol
e> _     i
OjTr
                 O
                    o ,
                 O
                    o-
                                                           4-	h
                                                                     . .o ^8
                                                                     ^^» *>?
                                                            UPTflKE
                                                            RECOVERY
i     i     i    I
                              +—I-
                              50    "    100    "   ISO   "    260

                              MG  fiPPLICflTION,  KG/Hfl
                                            .o
                                            sr
                                          ..o  >
                                            Ol  *Hs
                                                                         LLJ
o
                          Figure 74.  Estimated magnesium recovery by rye.

-------
o
CTl
o



 «t

UJ S.


cr
^-
Q_



CE ^
                                       S     I
                                         4-	S-
                                                           ECOVERY
              1 - 1
                                      +
1-
H	1-
                            200       400      ©00       800

                             Nfl  flPPLICflTION,  KG/Hfl
                                                                    .n >
                                                                    o O
                                                                      CJ
                          Figure 75.  Estimated sodium recovery by rye.

-------
   AJ-
                  4™	h—+
   fi
X
o
UJ
CL  -'
U.
                            UPTflKE
                                     J-S *Xe
                                     JLo
                                                      yj
                            RECOVERY
2         1         §        8

FE  flPPLICRTION,  KG/Hfi
                                                  so
          Figure 76.  Estimated iron recovery by rye.

-------
                        H	1	1	i—\	\	1	h—f
o
oo
               2E a
                                                        UPTRKE
                                                                 -
                                                                    oc
                                                                    uu
                                                                 .0 >
                                                                  fa w-i
                                                        RECOVERY
                                 i—i—i-
 '         2    '   "1	'	t

ZN  RPPLICflTION,  KG/Hfl
                                                                 -o
                       Figure 77.  Estimated zinc recovery by rye.

-------
   O.
UJ
o
cr
C£
O
u_
oc
Q
     0
  8    !     1	h-—h-—h—fr-
              4—1	1     I 	h—I	-I-	1-
     320

ftPPUCfiTIQN,   KG/Hfl
800
          Figure  78.  Estimated yield response of ryegrass.

-------
                                                            or
                                                            o
                                                            UJ
                                                            IT
Figure 79.   Estimated nitrogen recovery by ryegrass.

-------
   S-
o
d
I—
a.
^ - 1
    o
                            i - 1 - 1 - 1
                                           UPTflKE
                                                        CC
                                                        yj
                                                     .o  >
                                               yj
                                           f   cc

                                             .  0,
                                            ECQiERY

                                 4-	S	1
                                            •o
              120       1

      P  RPPLICflTIONf  KG/Hfl
        Figure 80.  Estimated phosphorus recuvery by ryegrass.

-------
   o
   4O-
CC o
x

o
CC
H-
a_
I     I     i	h
                                                       o
                                                       -o
                                            UPTflKE
                                                       o
                                                       -o
                                                         £C
                                                          O
                                                          O
                                                          UJ
                                                          cc
                                                       e
                                            RECOVERY
         H	4-
              30        ©0        90        120

                K  flPPLICflTION,
                                                     ISO
         Figure 81.  Estimated potassium recovery by ryegrass.

-------
          +-—I	h—+
o. _
Q- S-
                                                 . .O
                                                   cc
                                                   LU
                                                  O
                                                  LU
                                               •A
      I     I
                                8    1     B
                            480
                                        640
          Cfl  flPPLICflTION,
@00
      Figure 82.  Estimated calcium recovery by ryegrass.

-------
-h
0
I „ I.., ,. 	 p i „,. 	 	 	 I 	 L 	 	 	 I 	 	 	 .1 	 1 	 ., 	 	 1
50 ' 100 ISO Pnn ^e

•O
e"i
     HG  flPPLICflTION,  KG/Hfl
Figure 83.  Estimated magnesium recovery by ryegrass.

-------
CT o
   ISin
   0>
X
o


 «.
UJ O.

cz
g-
  0
                                          WFFflKE
                              •2 ^
                              |S> «X

                                  *!
                                 >-
                                 cc

                             J_o >
                                          RECOVEflY
              200        100
        800
ICflTION,  KG/Hfl
        Figure 84.  Estimated sodium recovery by ryegrass,

-------
o
ID

yj
           i      i -—i—+
                       ,o
                                                 UIPTRKE
                                                  RECOVERY
                                                                CJ
                                                                LU
                      -~S  u-
           ;     I     l
4—-f
                FE
           Figure 85.   Estimated iron  recovery by ryegrass,

-------
QC



O
O.  --
         -I	h	!	h	1	
                                                   -§ i^
                                                      O
                                                      yj

                                                      £C


                                                      z
                                         RECOVERY
         ^—h—h—i—i
              1         2         3

             IH flPPLICRTION,  KG/Hfl
                                         4—+
•o
         Figure 86.  Estimated zinc recovery by ryegrass.

-------
Parks and Fisher (1958) were approximately:  P = 0.25%, |< = 3.0%, Ca = 0.7% and
Mg = 0.5%.  These differences probably reflected differences in chemical
ratios applied, soil  characteristics and crop variety.  As with rye, K uptake
exceeded application  (Figure 81) at the lower rates, indicating potential
deficiency and need for supplemental K.  Other elements appeared to be avail-
able in adequate amounts (Figures 79-86).   A beneficial effect was provided
by Fe and Zn as with  rye.

     Three cuttings would  be expected.   At 160 kg/ha (140 Ib/acre) of applied
N, yield of dry forage was estimated to be 4 mtons/ha (1.8 tons/acre) from
Figure 78.  The corresponding yield of greenchop (15% dry matter) was 27
mtons/ha (12 tons/acre).

GROWTH RESPONSE OF CROPS

Introduction

     In 1972, field experiments were conducted to measure plant growth and
nitrogen uptake with  age under effluent irrigation.   The crops studied and
their varieties are listed in Table 23.  Plots were  30 m x 30 m (100 ft x
100 ft).  Irrigation  rates were 50, 100, 150 and 200 mm/week at an intensity
of 13 mm/hr (0.5 in./hr) following the schedule in Table 24.  All plots were
prepared by disking,  plowing and disking.   All crops were planted on April  23,
1972 in 0.9 m x 30 m  (3 ft x 100 ft) rows.  Seeding  rates were as follows:
corn   17 kg/ha, sorghum x sudangrass - 11 kg/ha and kenaf - 11 kg/ha.   Begin-
ning in the fourth week after planting, duplicate samples, 91.5 cm x 91.5 cm
in size, were clipped from each plot.  Samples were  weighed, chopped, dried at
70°C for 24 hours, and weighed again.  Composite samples were ground in a
Wiley mill and triplicate  0.500 g samples  were analyzed for Kjeldahl_N  (USEPA
1971).  Composite effluent samples were collected each week and analyzed for
Kjeldahl-N (USEPA, 1971) and for N03-N.

     Some aspects of  this  study have been  discussed  elsewhere (Overman and
Nguy, 1975 and Overman, 1975).

Results

     Measurements and estimates were made  of green weight, dry matter content,
dry weight, nitrogen  content, nitrogen uptake and nitrogen recovery.  Esti-
mates were made of harvest time for optimum nitrogen recovery.

Corn - Pioneer 3369 A
     Forage data were collected for irrigation rates of 50,  100, 150 and 200
mm/week.   Yield of green forage increased with age (Table 25-28).  Dry matter
content showed a concurrent increase,  while N content decreased (Figure 87a).
The crop showed a resultant increase in dry forage with age  and also with
irrigation rate (Figure 87b).   These trends have been reported by Bar-Yosef
and Kafkafi (1972).
                                    118

-------
   TABLE 23.  CROPS AND VARIETIES USED IN GROWTH STUDY


   	Crop	Variety	

    Corn                            Pioneer 3369A
                                    McNair   440V

    Sorghum x sudangrass            Asgrow Grazer S

    Kenaf                           Everglades 41
     TABLE 24.  IRRIGATION SCHEDULE FOR GROWTH STUDY

 Rate           Dose                  Application
mm/week     mm/irrigation             day of week


  50             50                       Wed.

 100             50                   Tues., Thurs.

 150             50                 Mon., Wed., Fri.

 200             50             Mon., Tues., Thurs., Fri
                          119

-------
TABLE 25.  GROWTH RESPONSE OF CORN (PIONEER 3369A)  AT 50 MM/WEEK
Age
days
0
25
32
39
47
53
60
67
77
84
95
Green
Weight
mton/ha
0
0.41
1.12
2.00
5.72
14.7
20.6
31.6
30.5
25.9
50.0
Dry
Matter
%

11.8
12.2
11.7
12.2
10.6
12.0
16.4
20.8
24.4
21.4
Dry
Weight
mton/ha
0
0.048
0.14
0.23
0.70
1.56
2.48
5.19
6.34
6.31
10.7
N
%
_
3.36
3.68
2.64
2.71
1.51
1.50
1.25
0.95
1.11
1.70
N
kg/ha
0
1.6
5.1
6.1
19
24
37
65
60
70
182

TABLE 26.   GROWTH RESPONSE  OF CORN (PIONEER 3369A)  AT  100  MM/WEEK

Age
days
0
25
32
39
47
53
60
67
77
84
95
Green
Weight
mton/ha
0
0.48
2.21
5.28
12.0
27.5
43.5
52.5
59.4
64.8
65.4
Dry
Matter
%

12.5
11.1
10.3
9.7
11.0
13.6
14.6
19.6
22.4
20.0
Dry
Weight
mton/ha
0
0.060
0.24
0.54
1.16
3.02
5.91
7.65
11.6
14.5
13.1
N
%

3.36
3.48
3.28
2.88
_
1.85
1.28
1.22
1.06
1.41
N
kg/ha
0
2.0
8.3
18
33
_
109
98
141
154
185
                               120

-------
TABLE 27.  GROWTH RESPONSE OF CORN (PIONEER 3369A) AT 150 MM/WEEK

Age
days
0
25
32
39
47
53
60
67
77
84
95
Green
Weight
mton/ha
0
0.54
2.01
4.20
12.9
25.8
41.1
48.3
69.0
87.0
64.4
Dry
Matter
%

12.1
10.4
10.2
10.2
9.0
12.2
13.8
19.4
25.8
20.3
Dry
Weight
mton/ha
0
0.065
0.21
0.43
1.32
2.32
5.00
6.67
13.4
22.5
13.1
N
%

3.43
3.37
3.27
2.30
_
2.44
1.49
1.31
1.33
1.28
N
kq/ha
0
2.2
7.1
14
30
_
122
99
175
300
168

TABLE 28.  GROWTH RESPONSE OF CORN (PIONEER 3369A) AT 200 MM/WEEK

Age
days
0
25
32
39
47
53
60
67
77
84
95
Dry
Weight
mtons/ha
0
0.65
2.04
5.16
16.1
31.0
43.0
62.8
75.0
99.8
70.0
Dry
Matter
%

18.5
14.1
11.2
11.0
9.8
15.2
14.0
16.4
20.0
17.6
Dry
Weight
mton/ha
0
0.12
0.29
0.58
1.77
3.04
6.53
8.80
12.3
20.0
12.3
N
%
_
3.61
3.71
3.37
2.52
2.32
2.63
1.31
1.29
1.51
1.46
N
kg/ha
0
4.3
11
20
45
70
172
115
159
302
180
                               121

-------
             EO  50 HM/HEEK
             O  200
                     lid         60

                    flGE,  DfiTS
100
Figure 87.   Response of nitrogen content,  dry weight  and
           nitrogen recovery for corn (Pioneer 3369A).
                       122

-------
TABLE 29.  ESTIMATED YIELD AND NITROGEN RESPONSE OF CORN
           (PIONEER 3369A) AT 50 AND 200 MM/WEEK



Age
days
30
35
40
45
50
55
60
65
70
75
80
85
90


N
%
3.80
3.40
3.00
2.60
2.25
1.95
1.70
1.50
1.35
1.25
1.20
1.15
1.10
50
Dry
Weight
mton/ha

0.05
0.2
0.5
1.1
1.8
2.7
3.7
4.7
5.8
7.1
8.3
9.7
mm/week

N
kg/ha

2
6
13
25
35
46
56
64
73
85
96
107
200
Dry
Weight
mton/ha

0.3
0.7
1.4
2.3
3.7
5.6
7.6
10.0
12.7
15.7
18.8
22.1
mm/week

N
kg/ha

10
21
36
52
72
95
114
135
159
188
216
242

     TABLE 30.   ESTIMATED NITROGEN  RECOVERY  BY  CORN
                (PIONEER 3369A)  AT  50  AND  200 MM/WEEK

50 mm/week
Age
days
35
40
45
50
55
60
65
70
75
80
85
90
Harvested
kg/ha
2
6
13
25
35
46
56
64
73
85
96
107
Applied
kg/ha
90
103
116
129
142
155
168
180
193
206
219
232
Recovered
%
2
6
11
19
25
30
33
36
38
41
44
46
200 mm/week
Harvested
kg/ha
10
21
36
52
72
95
114
135
159
188
216
242
Applied
kg/ha
360
412
464
516
568
620
672
720
772
824
876
928
Recovered
%
3
5
8
10
13
15
17
19
21
23
25
26
                          123

-------
     Due to the scatter obtained for both N content and dry weights, smooth
curves were visually fitted to the data.  A single curve was used for N con-
tent (Figure 87a), while separate curves were drawn for dry weights (Figure
87b).  Values from these curves were then used to estimate N uptake with age
(Table 29).  Applied N from planting to a particular age was estimated from
the average N content of the effluent for the crop season, irrigation rate
and time of irrigation.  Recovery of N was then calculated as the ratio of
harvested to applied (Table 30).   Recovery increased with age and was lower
for 200 mm/week than for 50 mm/week (Figure 87c).  This latter result is in
agreement with yield data presented above.  For 50 mm/week, recovery effi-
ciency  reached  approximately 50% at 90 days.  The crop had not reached
maximum N recovery, even at 90 days.

Corn - McNair 440 V

     Green and dry forage yields  increased with age and irrigation rate
(Tables 31-34).   Dry matter content rose, while N content declined with age.
Nitrogen uptake showed a general  increase with age and irrigation rate.

     Estimates of N content were  obtained from Figure 88a.  Similarly, esti-
mates of dry forage were taken from Figure 88b for 50 and 200 mm/week.  These
values were then combined to estimate N uptake (Table 35).  Nitrogen recovery
was finally calculated (Table 36) for 50 and 200 mm/week.   Recovery increased
with time (Figure 88c) and was higher at the lower application rate.  The
corn approached its maximum N recovery at 80 days, but never reached 50%.

Sorghum x Sudangrass

     Samples were only collected  for the first harvest period.   Green and
dry forage yields increased with  age and irrigation rate (Tables 37-40),  while
N content showed a decrease.  Crop uptake of N increased with age and with
irrigation rate.

     Estimates of N content (Figure 89a) and dry weight (Figure 89b) were
combined to calculate N uptake at 50 and 200 mm/week (Table 41)  and N recovery
(Table 42).   Recovery increased with age (Figure 89c), and reached a peak
around 65 to 70 days.  Efficiency of recovery was greater for the lower irri-
gation rate, but only reached approximately 25%.

     From these  results a harvest age of around 9 weeks appears  optimum for
the first cutting.

Kenaf

     Yields  of green and dry forage increased with age and with irrigation
rate (Table  43-46).   Even though  N content decreased"with  age,  N uptake  showed
an increase  with age and irrigation rate.   Estimates of N content (Figure 90a)
and dry weight (Figure 90b) for 50 and 200 mm/week were combined to calculate
N  uptake by  kenaf (Table 47).   Nitrogen recovery was then calculated (Table
48) with age at  50 and 200 mm/week.   Curves of N recovery (Figure 90c) showed
definite peaks around 70 days, reaching 30% recovery for 50 mm/week and only
about 10% for 200 mm/week.   Optimum harvest time appears to be about 10 weeks.

                                    124

-------
 TABLE 31.  GROWTH RESPONSE OF CORN  (.MCNAIR 44oy) AT so MM/WEEK
Age
days
0
26
33
40
48
54
61
68
77
85
Green
Weight
mton/ha
0
0.22
0.68
2.05
9.12
9.39
13.3
20.1
21.0
22.1
Dry
Matter
%

13.5
11.5
19.0
12.8
15.8
18.4
15.4
19.4
21.2
Dry
Weight
mton/ha
0
0.030
0.078
0.39
1.17
1.48
2.45
3.10
4.07
4.68
N
%

3.61
4.09
2.58
3.07
1.46
3.17
0.89
1.33
0.78
N
kg/ha
0
1.1
3.2
10
36
22
78
28
54
37

TABLE 32.  GROWTH RESPONSE OF CORN (MCNAIR 440V) AT 100 MM/WEEK

Age
days
0
26
33
40
48
54
61
68
77
85
Green
Weight
mton/ha
0
0.25
1.78
3.33
13.6
18.4
37.9
40.5
51.8
37.3
Dry
Matter
%

11.9
11.4
13.1
10.4
11.4
15.8
12.4
19.6
20.0
Dry
Weight
mton/ha
0
0.030
0.20
0.44
1.41
2.10
5.99
5.02
10.2
7.46
N
%
.
3.89
3.63
3.35
3.02
1.94
2.51
1 .35
1.57
-
N
kg/ha
0
1.2
7.3
15
42
41
150
68
160
-
                               125

-------
TABLE 33.  GROWTH RESPONSE OF CORN (MCNAIR 440V)  AT 150 MM/WEEK

Age
days
0
26
33
40
48
54
61
68
77
85
Green
Weight
mton/ha
0
0.35
1.94
3.04
10.3
22.0
48.0
45.6
41.2
47.3
Dry
Matter
%

11.9
11.7
12.0
10.4
10.8
15.0
14.0
19.2
19.8
Dry
Weight
mton/ha
0
0.042
0.23
0.36
1.07
2.38
7.20
6.38
7.91
9.36
N
%
_
4.29
4.15
3.77
2.87
2.55
1.84
1.53
1.85
-
N
kg/ha
0
1.8
10
14
31
61
132
211
146
—

TABLE 34.   GROWTH RESPONSE  OF CORN  (MCNAIR 440V)  AT 200 MM/WEEK

Age
days
0
26
33
40
48
54
61
68
77
85
Green
Weight
mton/ha
0
0.31
1.01
2.36
7.83
19.4
30.3
42.5
56.7
46.6
Dry
Matter
%

23.1
13.6
15.7
7.9
13.6
14.6
13.4
14.8
17.6
Dry
Weight
mton/ha
0
0.072
0.14
0.37
0.62
2.64
4.42
5.70
8.39
8.20
N
%

3.18
4.30
3.71
2.05
2.97
1.09
1.39
1.21
_
N
kg/ha
0
2.3
6.0
14
13
78
48
79
102
_
                             126

-------
UJ o.
> 01

o

CJ Q
III ,_=

CC
                                 HH/WEEK
                                    50
                                   200
GE
            CB)
S   50 MM/WEEK

O   200
                                    m
            Cfl)
                                  I     B     1      !
                                      60
       Figure 88.  Response of nitrogen content, dry weight and

                  nitrogen recovery for corn (McNair 440V).
                              127

-------
TABLE 35.   ESTIMATED  YIELD  AND  NITROGEN  RESPONSE OF CORN  (MCNAIR 440V)
                        AT  50 AND  200 MM/WEEK


Age
days
30
35
40
45
50
55
60
65
70
75
80

N
%
4.00
3.50
3.05
2.65
2.30
1.95
1.70
1.50
1.35
1.25
1.10
50
Dry
Weight
mton/ha

0.2
0.5
0.8
1.2
1.6
2.1
2.6
3.2
3.8
4.5
mm/week
N
kg/ha
_
7
15
21
28
31
36
39
43
48
54
200
Dry
Weight
mton/ha
_
0.3
0.6
1.1
1.9
2.8
3.9
5.1
6.4
7.8
9.3
mm/week
N
kg/ha
.
11
18
29
44
55
66
77
87
98
112

    TABLE 36.   ESTIMATED  NITROGEN RECOVERY BY CORN  (MCNAIR 440V)
                       AT  50 AND 200 MM/WEEK

Age
days
35
40
45
50
55
60
65
70
75
80
Harvested
kg/ha
7
15
21
28
31
36
39
43
48
54
Applied
kg/ha
90
103
116
129
142
155
168
180
193
206
Recovered
%
8
15
18
22
22
23
23
24
25
26
Harvested
kg/ha
11
18
29
44
55
66
77
87
98
112
Applied
kg/ha
360
412
464
516
568
620
672
720
772
824
Recovered
%
3.1
4.4
6.2
8.5
9.7
11
11
12
13
14
                                128

-------
TABLE 37.  GROWTH RESPONSE OF SORGHUM X SUDANGRASS
                   AT 50 MM/WEEK

Age
days
0
27
34
41
49
55
62
69
Green
Weight
mton/ha
0
0.29
1.01
2.62
5.52
12.2
27.1
19.6
Dry
Matter
%
_
16.3
14.8
8.0
13.2
14.0
16.0
16.6
Dry
Weight
mton/ha
0
0.047
0.15
0.21
0.73
1.71
4.34
3.25
N
%

3.99
3.67
3.41
2.62
1.74
1.37
1.28
N
kg/ha
0
1.9
5,5
7.2
19.1
30.0
59.5
41.6

TABLE 38.  GROWTH RESPONSE OF SORGHUM X SUDANGRASS
                   AT 100 MM/WEEK

Age
days
0
27
34
41
49
55
62
69
Green
Weight
mton/ha
0
0.25
1,36
3.70
8.52
17.8
25.7
35.2
Dry
Matter
%

15.4
14.1
8.9
11.8
15.0
15.0
14.6
Dry
Weight
mton/ha
0
0.015
0.19
0.33
1.00
2.67
3.86
5.14
N
%
.
4.39
4.05
3.19
2.75
2.00
1.60
1.42
N
kg/ha
0
0.66
7.7
10.5
27.5
53.4
61.8
73.0
                        129

-------
TABLE 39.   GROWTH RESPONSE OF SORGHUM X SUDANGRASS
                  AT 150 MM/WEEK

Age
days
0
27
34
41
49
55
62
69
Green
Weight
mton/ha
0
0.34
1 .49
3.25
8.46
17.1
29.7
35.8
Dry
Matter
%
_
15.8
12.9
9.4
15.2
15.2
15.8
16.0
Dry
Weight
mton/ha
0
0.054
0.19
0.31
1.29
2.60
4.69
5.73
N
%
.
4.21
3.69
3.75
2.87
2.30
1.60
1.53
N
kg/ha
0
2,3
7.0
11.6
37.0
59.8
75.0
87.7

TABLE 40.   GROWTH RESPONSE  OF  SORGHUM  X  SUDANGRASS
                  AT 200 MM/WEEK

Age
days
0
27
34
41
49
55
62
69
Green
Weight
mton/ha
0
0.43
1.44
3.47
8.64
21.8
32.4
37.4
Dry
Matter
%

12.7
13.3
7.5
10.6
14.8
14.6
18.0
Dry
Weight
mton/ha
0
0.054
0.19
0.26
0.92
3.22
4.73
6.73
N
%

4.93
3.95
3.75
2.52
2.41
1.53
1.32
N
kg/ha
0
2.7
7.5
9.8
23.2
77.6
72.4
88.8
                        130

-------
                                     +-—h
S*
oc
UJ Os
> «
O
tJ »
                                 200
           (B)
CE


X
50 HM/WEEK

?00
                           ffl
                 /
                                  ©'
                                   /
                   O,
                          4—f
                          4—f
                          no

                         flGE,  DflTS
                                    too
       Figure 89.  Response of  nitrogen  content,  dry weight and

                  nitrogen recovery for sorghum  x sudangrass.
                             131

-------
TABLE 41.   ESTIMATED YIELD AND  NITROGEN  RESPONSE  OF  SORGHUM  X  SUDANGRASS
                          AT  50 AND  200  MM/WEEK


Age
days
30
35
40
45
50
55
60
65
70
75

N
%
4.50
3.90
3.40
2.90
2.40
2.00
1.65
1.35
1.15
1.00
50
Dry
Weight
mton/ha
0.10
0.15
0.25
0.50
0.85
1.40
2.10
2.90
3.70
4.65
mm/ week
N
kq/ha
5
6
9
15
20
28
35
39
41
47
200
Dry
Weight
mton/ha
0.25
0.40
0.80
1.40
2.20
3.20
4.35
5.65
7.00
8.55
mm/ week
N
kg/ha
9
16
27
41
53
64
72
76
81
86

     TABLE  42.   ESTIMATED NITROGEN RECOVERY BY SORGHUM X SUDANGRASS
                         AT  50 AND 200 MM/WEEK


Age
days
30
35
40
45
50
55
60
65
70
75
50
Harvested
kg/ha
5
6
9
15
20
28
35
39
41
47
mm/week
Applied
kg/ha
77
90
103
116
129
142
155
168
180
193

Recovered
%
6
7
9
13
16
20
23
23
23
24
200
Harvested
kg/ha
9
16
27
41
53
64
72
76
81
86
mm/week
Applied
kg/ha
308
360
412
464
516
568
620
672
720
772

Recovered
%
3
4
7
9
10
11
12
12
11
11
                                  132

-------
 TABLE 43.  GROWTH RESPONSE OF KENAF AT 50 MM/WEEK

Age
days
0
28
35
42
50
56
63
70
78
85
98
Green
Weight
mton/ha
0
0.51
1.34
5.75
6.72
11.0
12.7
26.8
28.5
27.2
45.5
Dry
Matter
%
_
11.8
11.2
11.6
13.4
12.4
16.0
8.0
15.4
15.8
18.6
Dry
Weight
mton/ha
0
0.060
0.15
0.67
0.90
1.36
2.03
2.14
4.39
4.30
8.46
N
%

4.89
4.24
3.17
3.27
2.73
1.73
1.86
1 .58
1.42
1.23
N
kg/ha
0
2.9
6.4
21.2
29.4
37.1
35.1
39.8
69.4
61.1
104.0

TABLE 44.  GROWTH RESPONSE OF KENAF AT 100 MM/WEEK

Age
days
0
28
35
42
50
56
63
70
78
85
98
Green
Weight
mton/ha
0
0.47
1.70
7.70
8.58
13.9
18.6
24.6
28.6
28.0
51.9
Dry
Matter
%
_
11.4
10.2
6.8
8.5
10.8
15.0
9.4
18.2
19.4
16.8
Dry
Weight
mton/ha
0
0.054
0.17
0.52
0.73
1.50
2.79
2.31
5.21
5.43
8.72
N
%
_
5.03
4.44
3.38
3.03
2.89
1.94
1.81
1.92
2.28
1.72
N
kg/ha
0
2.7
7.5
17.6
22.1
43.4
54.1
41 .8
100.0
124.0
150.0
                       133

-------
TABLE 45.  GROWTH RESPONSE OF KENAF AT 150 MM/WEEK

Age
days
0
28
35
42
50
56
63
70
78
85
98
Green
Weight
mton/ha
0
0.68
1.96
7.34
9.96
12.6
12.4
21.4
16.5
27.8
42.3
Dry
Matter
%
__
10.7
10.1
6.5
6.1
11.2
14.2
9.6
19.8
21.6
15.6
Dry
Weight
mton/ha
0
0.073
0.20
0.47
0.61
1.41
1.76
2.05
3.27
6.00
6.60
N
%
_
3.78
3.72
3.35
3.35
3.56
2.18
1.74
1.15
1.25
2.60
N
kg/ha
0
2.8
7.4
15.7
20.4
50.2
38.4
35.7
37.6
75.0
172.0

TABLE 46.   GROWTH RESPONSE  OF  KENAF  AT  200  MM/WEEK

Age
days
0
28
35
42
50
56
63
70
78
85
98
Green
Weight
mton/ha
0
0.83
2.46
6.43
11.1
16.2
22.2
26.5
32.7
40.3
51.1
Dry
Matter
%

10.1
10.0
10.8
8.4
11.0
13.0
10.6
16.0
17.8
16.7
Dry
Weight
mton/ha
0
0.080
0.25
0.69
0.93
1.78
2.89
2.81
5.23
7.17
8.53
N
%

4.88
4.24
2.79
4.19
3.17
2.22
1.10
3.12
2.84
1.90
N
kg/ha
0
3.9
10.6
19.2
39.0
56.4
64.2
30.9
163.0
204.0
162.0
                        134

-------
                          I     !      I     I
yj 0
a:
CB)
                  m  50  HM/WEEK
                  o  eoo
                                           ^JU
                                      Q
   o-
                               ©
                              •E
               I     1      I
                                                 o
              4—4
                                                        fflp-
                                                       • ED
     1
   60
DflTS
                                             100
        Figure 90.  Response of nitrogen content, dry weight and
                  nitrogen recovery for kenaf.
                           35

-------
TABLE 47.   ESTIMATED YIELD AND NITROGEN  RESPONSE OF KENAF
                  AT 50  AND 200 MM/WEEK


Age
days
30
35
40
45
50
55
60
65
70
75
80
85
90
95

N
%
4.75
4.35
3.95
3.55
3.20
2.85
2.50
2.25
1.95
1.70
1.50
1.35
1.20
1.10
50
Dry
Weight
mton/ha
0.06
0.18
0.30
0.55
0.90
1.30
1.75
2.25
2.85
3.45
4.05
4.70
5.35
6.00
mm/week
N
kg/ha
3
8
12
20
29
37
44
51
56
59
61
63
64
66
200
Dry
Weight
mton/ha
0.10
0.25
0.45
0.80
1 .20
1.70
2.35
3.10
3.90
4.85
5.80
6.85
7.90
8.95
mm/ week
N
kg/ha
5
11
18
28
38
48
59
69
76
82
87
92
95
98

     TABLE  48.   ESTIMATED NITROGEN RECOVERY BY  KENAF
                  AT  50 AND  200 MM/WEEK

50 mm/week
Age
days
30
35
40
45
50
55
60
65
70
75
80
85
90
95
Harvested
kg/ha
3
8
12
20
29
37
44
51
56
59
61
63
64
66
Applied
kg/ha
77
90
103
116
129
142
155
168
180
193
206
219
232
245
Recovered
%
4
9
12
17
22
26
28
30
31
31
30
29
28
27
200 mm/week
Harvested
kg/ha
5
11
18
28
38
48
59
69
76
82
87
92
95
98
Applied
kg/ha
308
360
412
464
516
568
620
672
720
772
824
876
928
980
Recovered
%
1.6
3,1
4.4
6.0
7.4
8.5
9.5
10.3
10.6
10.6
10.6
10.5
10.2
10.0
                          136

-------
Summary

     The crops studied showed a lag time of 30-40 days in their growth
curves.  Rag!and et_ al_. (1965) reported similar results with corn.  Dry matter
yield increased with age, while N content decreased.  Bar-Yosef and Kafkafi
(1972) observed similar response with corn.  Nitrogen recovery by the crops
showed a continual increase throughout the study period.  Estimates were made
of harvest age for optimum N recovery (Table 49).  For Pioneer 3369 A  corn


        TABLE 49.  ESTIMATED HARVEST AGE FOR OPTIMUM NITROGEN RECOVERY

        	Crop	Age, weeks	

               Corn

                    Pioneer 3369 A                      >13
                    McNair   440V                       12

               Sorghum x Sudangrass                      9

               Kenaf                                    10
this value exceeded 13 weeks, with 14 weeks being a good estimate.   The value
for sorghum x sudangrass represented the first harvest only.  The second
harvest would be about the same, while the third harvest would cover a shorter
period due to reduced growth later in the season.

     Effluent irrigation had two beneficial effects on crop growth  - addition
of nutrients and reduction of soil moisture stress.  Higher levels  of applied
N produced greater uptake of N, in agreement with findings of Parks et al.
(1970).  Parks and Knetsch (1959) observed higher yields at reduced moisture
tension.  However, N recovery efficiency decreased with application rate,
with 50% recovery obtained at approximately 50 mm/week (2 in./week).

GROWTH RESPONSE OF TREES

     Field plots were established at Tallahassee by W. H. Smith and D. M.
Post, School of Forest Resources and Conservation, University of Florida.
The study was aimed at screening several species as to their suitability for
wastewater irrigation on well drained sandy soil.  Growth response  was
measured on several species (Table 50) over a three year period (Sinith and
Evans, 1977, and Smith et al_., 1978).

     Tree heights were measured 1, 2 and 3 years after planting.  Average
values from the three plots receiving 50, 100 and 200 mm/week were  averaged
and graphed to show growth trends (Figures 91-94).  Cottonwood showed the
most rapid growth (Figure 91) during the 3-year period.  Cottonwood, sycamore,
black locust, green ash, Chinese elm, and tulip poplar exhibited linear growth

                                     137

-------
(Figures 91  and 92).   Sweetgum, bald cypress and red cedar showed decreasing
growth rates (Figure 93),  while loblolly pine showed a rapid increase in
growth rate  during the 3-year period.
     All of  the species reported appeared to be suitable for effluent irri-
gation.
                   TABLE 50.   TREES IRRIGATED AT TALLAHASSEE
                Common Name
   Scientific Name
                Cottonwood
                Sycamore
                Black locusts
                Green ash
                Chinese elm
                Tulip poplar
                Sweetgum
                Bald cypress
                Red cedar
                Loblolly pine
         penn6 yl.vaYii.ca
Taxodium dJJ>£L
      AuA A
      tazda
                                     138

-------
              0_
CO
to
                          Figure 91.  Growth response of Cottonwood, Sycamore
                                      and Black Locust to effluent irrigation,

-------
1/1
                GREEN  R5H
                CHINESE  EL
                TULIP  PDPLRR
          Figure 92.  Growth response of Green Ash, Chinese Elm
                   and Tulip Poplar to effluent irrigation.

-------
CD    BflLD  CYPRESS
      RED CEDflR
 Figure 93.  Growth response of Sweetgum,  Bald Cypress
          and  Red Cedar to effluent irrigation.

-------
Figure 94.
Growth response of Loblolly Pine to
effluent irrigation.

-------
                                  SECTION 7

                       ANALYSIS OF TRANSPORT PROCESSES
INTRODUCTION
     Laboratory experiments were conducted to clarify the interplay among
various processes operating in the field system.  Attention was focused on
phosphorus and cations (including NH^) because of their particular importance
to water quality and to plant growth.  Crop response under effluent irrigation
was influenced by the availability of N, P and K in the soil solution for crop
uptake through the root system.  For N and K this availability was related to
cation exchange - transfer between solution and surface phases.  For P, anion
exchange and chemical reaction were the critical factors.  Measurements were
made to quantify the rates of some of the processes and to establish correla-
tions among the processes of convection, dispersion, exchange and chemical
reaction.  In both phosphorus fixation and cation exchange, mathematical models
were developed of transport and kinetic components to provide an analytical
framework.  Results from these laboratory studies were used to aid in explain-
ing field results.

PHOSPHORUS TRANSPORT

     In Section 5 it was observed that phosphorus in wastewater applied to
land decreased in concentration as the water percolated down through the soil,
and that ammonium acetate extractable phosphorus also decreased with depth.
Two models were developed to quantify the relevant processes involved.   Cho
et al_. (1970), Novak et al_. (1975), Novak and Adriano (1975) and Monke  et_ aJL
TT974) previously applied the theory of convective diffusion to phosphorus
movement in soil.  This analysis focused on the coupling among the various
processes and quantified the kinetics of fixation in this study of effluent
irrigation.

     Flow experiments were conducted in a packed-bed reactor.  The reactor was
constructed from acrylic plastic 4.7-cm ID and 10 cm in length.  End plates
were grooved to allow uniform entry and exit of solution.  Filter paper was
used at each end to confine the soil.  Sampling ports were installed at depths
of 2, 4, 6 and 8 cm.   Lakeland fine sand was dried in a forced air oven at
105°C for 24 hours and then packed into the reactor to a bulk density of 1.73
g/cm3.    The reactor was then purged with C02 gas to displace other gases,
followed by saturation with degassed distilled water.  Stock solution of
KH2P04 containing 10 mgA P was fed to the reactor with a peristaltic pump at
pore velocities of 0.118, 0.256, 0.539 and 0.900 cm/min.  Flow was continued
until phosphorus concentration reached a steady value.  Orthophosphate  was
determined by the stannous chloride reduction method (APHA, 1971).


                                     143

-------
Equilibrium Model

     This model included four processes:  convection, dispersion, adsorption
and reaction.  Concentration in a volume increment changed due to convection,
or mass flow, of the solution through the increment.  Concentration gradients,
partly due to nonuniform flow velocity in the pores, caused mixing due to
diffusion.  Adsorption and desorption at particle surfaces induced changes in
solution concentration.  Finally, chemical  reactions, in solution or on the
particle surfaces, caused changes in solution concentration.  A dispersed flow
model of this system for one dimension was  given by (Smith, 1970):


                     D^4- 7|f - er - e  ff-- e |f = 0                 0)
                       r, £     O Z          O L     d t
                       d Z

where C = solute concentration in the liquid phase
      z = depth in the bed
      t - time
      r = chemical reaction
      S_ = solute concentration in the adsorbed phase
      JD = dispersion coefficient for the bed
      V = volume flux through the bed
      e = porosity of the bed

Here V was taken as constant with depth and time.  A first order chemical
reaction with coefficient k was assumed so  that

                     r = kC                                              (2)

Equilibrium adsorption was assumed to be linear with exchange coefficient  R
so that

                     S = RC                                              (3)

The utility of these assumptions for the packed bed reactor was determined
from the experimental  results.   Combination of Equations (1) - (3) yielded

                        2
                     D i_C _ v |C _ kc _ (]  + R) 9C = Q                  (4)
                       9z^     dz                8t

where D = D/e and V =  V/e were pore dispersion coefficient and pore velocity,
respectively.  Initial and boundary conditions to be used in the system were

                                                                         (5)

                                                                         (6)

                                                                         (7)
z
z

z
>
=

->
0
0

00
C
C

C
= 0
= C
0
+ 0
t
t

t
=
>

>
0
0

0
                                    144

-------
where  C0 was  the  feed  concentration for the reactor.   This system of equations
was  reduced to  the  dimension! ess  form
with
? > o
5 = 0
^ +00
$ = 0
<}> = 1
cf> -> 0
T - 0
T .> 0
T > 0
(9)
(10)
(11)
where
                                 5=4     T=°
                           a    2D      B    *\I D
 using £ as a characteristic  length.  The  steady  state  and  transient  solutions
 were, respectively,  (Overman et al., 1976)
                    !>s = exp  [ - ( \|a  + 3   - a) 5 J                         (12)
and
                      - 1 exp  [ - ( Ja2 +  3    a) U  x
                         [ exp (2  a2 + 32 C) x  e^fc  (    +  J (a2 + 32) T )
                                        j(a2 + 32)t') ]                   (13)
where subscript s refers to steady state and e/rfc represents the complimentary
error function.  It was convenient for purposes of analysis to define the
dimensionless variables


                        r—   v _      T _ /-,  , . x V2   t
and the dimensionless parameter


                                   32 _ 4kD
                               Y = "T = -7.2
                                   a     V


                                     145

-------
Equations (12) and (13)  were  then  converted  to  the  form
                        ,   =exp  r.      +Y-    z]
                        5              H  + Y'
and

                      ^- = {[  exp(2Z)


                          + eAfc  (—=,-  17 )  ]                         (15)
                                   2/<}>s = C/CS versus T
with Z as a  parameter, or, C/CS versus Z with T as a parameter.  With no
chemical reaction (k = 0), Y =  0 and Cs = C0 for all depths, as expected.

     For the special case Y  <  < 1, it was shown by Taylor series expansion
that Equation  (14)  reduced to

                             C
                             ^=  exp (-|z)                           (16)
                               o

and that
                        7  ~  *  7        T ~ —	
                        L    2D              4D  1 + R

     Steady state  distributions are shown in Figure 95  for the four veloc-
ities.  Distributions  were logarithmic as predicted by Equation (12).  Values
of the reaction coefficient  k were estimated from the slopes of these lines
using Equation (16).   The  dependence of k on velocity is illustrated in
Figure 96a.

     Estimates of  D and  R  were  obtained from the transient data.  Equation
(15) was fitted to data  as follows.  From a plot of C/CS versus t for a parti-
cular depth and velocity,  estimates were made of times tQt2, to,5 and to.7
corresponding to C/CS  =  0.2,  0.5 and 0.7, respectively.  Values'of To.2/T0.5
and TO.7 were obtained for these same values of C/CS from Equation (15) for a
range of values of Z.  The value of Z which satisfied the equality


                        T0.7 " T0.2     t0.7 " ^.2
                            T0.5            ^.5

was selected as  the  proper  value.  An estimate of D was then obtained from
D - Vz/2Z.   For  example,  with  z =  2  cm  and V = 0.118 cm/min, Z = 9.6


                                    146

-------
                                                   0,10
111 <0
                                      0.118 CM/MI ML
    Figure  95.   Steady state distributions of phosphorus
                for the packed-bed reactor.
                         147

-------
 X
f\J
 o ~.
    O'
    gj-
    ©
 cc
      ..   (fl)
 I
 O
                            4	1      I     I
                           0.10        0.60

                           V,   CM/MIN
Figure  96.  Dependence of reaction, exchange and  dispersion coefficients
           on velocity for the equilibrium model of phosphorus  transport
                              148

-------
was obtained.  The corresponding value of D was 0.012 cm2/min.  At each
velocity the four values of D were averaged.  Variation of D with velocity
1s shown in Figure 96c.  From the definitions of Z and T it was shown that


                                  Z2    z2
                                  L  -
                                       _ _
                                   T    D*t                                  '

where D* = D/(l + R).  Estimates of D* were obtained by substituting appro-
priate values Into Equation (17).  For example, with z = 2 cm and V = 0.118
cm/mi n, Z = 9.6 and T0 .5/t(j.5 = 0.0076 1/min, so that D* = 0.00033 cm2/min.
It follows that R = 361   At each velocity the four values of R were averaged.
The trend of R with velocity is shown in Figure 96b.

     The various coefficients showed strong dependence upon pore velocity.
An asymptotic increase in k with V was apparent (Figure 96a).  This suggested
that the reaction was not homogeneous (solution phase) as implied in the
model, but was heterogeneous (solid phase) and that k approached a limiting
value at higher velocities.  At the lower velocities reaction was limited by
diffusion of reactants to the particle surface (Smith, 1970).  Variation of
R with V (Figure 96b) indicated that adsorption and desorption coefficients
had different velocity dependence, so that their ratio changed with velocity.
At higher velocities this ratio approached a constant value, which implied
that their velocity dependence assumed similar form in the upper range.
Dependence of both k and R on V brought the equilibrium assumption into  ques-
tion, which led to the global  model, as discussed in the next section.   Levich
(1962) pointed out that surface reactions should be included as a boundary
condition.  However, geometric complexity of the solution/solid interface
necessitated including these effects as a sink term.  The dispersion coeffi-
cient showed a more-than-linear increase with velocity (Figure 96c).  Bear
(1972) has discussed some of the proposed correlations between D and V,
including linear and quadratic types.  The observed dependence reflected in
part description of a multi-dimensional  transport by a one-dimensional model.

     The assumption that y« 1 was justified, since Y= 0.0163, 0.0122,
0.0112 and 0.0108 at velocities of 0.118, 0.256, 0.539 and 0.900 cm/min,
respectively, were calculated from appropriate values of k and D.   This
simplified the calculations considerably.

     As mentioned in Section 5, a field plot was irrigated continuously  for
three days in July, 1970 at an intensity of 1.25 cm/hr.   At the end of three
days, soil solution samples were collected and analyzed for orthophosphate.
The distribution was logarithmic (Figure  13), as predicted above.  The  slope
of the regression line was 0.0401 I/cm.   For this velocity, a water content of
0.16 was estimated from Overman and West (1972).  The corresponding pore
velocity was estimated to be V = 0.13 cm/min.  From Equation (16)  the rate
constant was calculated  to be k = (0.0401 )(0. 13) = 0.0052/min.  This value
agreed closely with the  corresponding value from Figure 96a.

     The dispersed flow model  with equilibrium exchange and first order
chemical reaction agreed closely with both steady state and transient results.
Observed steady state distributions were logarithmic, as predicted.  Reaction


                                     149

-------
coefficients for laboratory and field studies agreed rather closely.  However,
correlations of reaction and exchange coefficients with velocity suggested
that the assumption of equilibrium between solution and adsorbed phases was
not entirely justified.  A more detailed description of the surface component
seemed desirable.

Kinetic Model
     In this model the assumption of equilibrium between solution and surface
phases was removed and the chemical  reaction was assumed to occur on the par-
ticle surface.  Thus the problem became one of heterogeneous kinetics (multi-
phase system) in contrast to homogeneous kinetics (single phase system).  For
equilibrium exchange, the heterogeneous system may be treated as an equivalent
homogeneous system.  This explains the apparent success of the equilibrium
model discussed above.  The kinetic component for this model was written in
the global sense (Smith, 1970), i_.e_. without regard to intermediate steps
between bulk solution and the adsorbed phase.  This implicitly assumed that
transfer to and from surfaces was kinetically controlled and not limited by
external diffusion.  By assuming reversible adsorption followed by an essen-
tially irreversible reaction on the surface, the kinetic scheme was written as
                                  kd

where A = solute concentration in adsorbed phase
      F = solute concentration in fixed phase
     ka = adsorption coefficient
     k^ = desorption coefficient
     kr = reaction coefficient

Adsorption, desorption and reaction were all  assumed to follow first order
kinetics and the kinetic equations were written as

                               —— = k C - k A                            (19)

and


                            |£ = k C - k,A -  k A                         (20)
                            d L    d     U     r

Concentration of the adsorbed  phase was expressed on a solution volume basis.

     The transport equation for one-dimensional dispersed flow was written as
                                     150

-------
Initial and boundary conditions were
                         z>0     C = 0      t = 0                       (22)
                         z = 0     C = C0     t >: 0                       (23)
                         z + »     C -> 0      t >: 0                       (24)
                         z>0     A = 0      t = 0                       (25)
In the development of the model the dispersion term was neglected.  Justifi-
cation for this follows below.  Equations (19) and (21) were combined to  give
                            3 r   3 r
                          V— + °-5±+kf-kA = n                       (?fi}
                          v 3z   9t   V   KdM   u                       uo;
where V = V/e.
     Steady state distributions were obtained
                                  As = KCS                                (27)
and
                             Cs = CQ exp ( -y- z )                          (28)
where

                                 K = IT-XTT-                              (29)
and
                                   k = krK                               (30)
For the case of no adsorption (ka = 0) the equations yielded As = 0 and
Cs = C0, as expected.  With adsorption, but no reaction (kr = 0), the results
were Cs = C0, as expected.
     By using definitions
                * - _        A* =         z* =        t* =
                    Cs           As      Z    £
                                              kO I/
                             H  9               a
                        a = k~ K          B = TiT
                             a
                                     151

-------
Equations (26) and (20) were written as


                                   i- aB(C* - A*) = 0                      (31)
and


                              !££•= B(C* - A*)                           (32)


subject to the conditions

                       z* > 0      C* = 0      t* = 0                    (33)

                       z* = 0      C* = 1      t* .> 0                    (34)

                       z* + oo      C* + 0      t* >: 0                    (35)

                       z* > 0      A* = 0      t* = 0                    (36)

Overman et al.  (1978) solved Equations (31) - (36) and obtained
                                       exp(-3 )  I  \| 4a32z*y dy          (37)
              "s               ~  "

and


         ~~ = A
7^ = •£- + exp(-agz*) exp[ - 3(t* - z*)] I  J 4ag2z*(t* - z*)'       (38)
               s

and


                         -r- = £-= 0        t* < z*                      (39)
                         Hs   us

where I0 was the modified Bessel function of first kind and zeroth order.  For
a system with no adsorption (a = 0), Equation (38) reduced to plug flow, viz.


                             t <          C = 0                          (40)
                             t>f        C = CQ                         (41)
as expected.
     Values for k  and kj were estimated from the transient data.  From a
graph of C/CS versus t, the time corresponding to C/C$ = 0,5 was estimated.
Then t* was calculated, using the appropriate pore velocity and sampling
depth.  Then K = t* - 1 was assumed.   With kr «kd, this gave ka/kd = t* - 1
                                     152

-------
Values of ka and kj were then chosen, subject to this constraint, until the
calculated curve agreed with the data.  This procedure was followed for all
depths and velocities.

     The model predicted a logarithmic distribution at steady state, as given
by Equation (28).  By using the slopes from Figure  95 , estimates were ob-
tained for kr from Equation (30).  This relationship established the relation-
ship between the apparent coefficient for the homogeneous reaction and the
coefficient for the heterogeneous reaction.

     All three kinetic coefficients varied with velocity (Figure 97).  Since
each curve showed asymptotic response, an empirical equation

                           k = km [ 1 -exp(-XV) ]                          (42)


was fitted for each process, where km and X were curve fitting parameters.
The resulting equations were:
m
                        k  = 3.12 [1 - exp(-3.71 V)]                     (43)
                         a

                        kd = 0.170 [1 - exp(-2.71 V)]                    (44)

and

                      kr = 0.000520 [1 - exp(-2.53 V)]                   (45)


These equations indicated that the rates followed the order adsorption >
desorption > reaction.  Since R for the equilibrium model was related to k
and k . for the kinetic model by


                                   R = r*-                                (46)
                                       kd

Equation (46) was used to calculate R for various velocities.  The values
were 23.9, 23.5, 20.6 and 19.0 at 0.118, 0.256, 0.539 and 0.900 cm/min,
respectively.  The decrease in R with V was related to the different velocity
dependence of k  and k ,.

     In the kinetic model, a global  scheme was used which neglected any inter-
mediate steps between bulk solution and adsorbed phases.   An alternative pos-
sibility was  that transfer from solution to the surface was diffusion limited
(Smith, 1970) in which case solution concentration adjacent to the particle
surface was lower than in bulk solution.  At higher velocity mass transfer
(by diffusion)  was greatly enhanced, so that adsorption became the limiting
step.   This coupling, then, gave rise to asymptotic increase of the global
coefficients  to maxima.   This line of analysis is being continued in another
study.
                                     153

-------
      O
Figure 97.  Dependence of adsorption, desorption  e»nd  reaction  coefficients
            on velocity for the kinetic model of  ph.osph.orus  transport,

-------
     Characteristic times for the processes of convection, dispersion,
adsorption, desorption and reaction were defined from Equations (19) - (21).
The times were:


                          convection        T  = —                       (47)
                          dispersion        T  = -g-                      (48)


                          adsorption        T  = -r—                      (49)
                                                  a

                          desorption        T  = 1—                      (50)
                          reaction          T  = —                      (51)
                                             r   Kr

These values were calculated for the 2-cm depth, where dispersion showed the
greatest relative importance.  Values of D from the equilibrium model and
the kinetic coefficients from the kinetic model were used.   Comparison of
values in Table  51  showed that dispersion and reaction were slow compared to
convection, adsorption and desorption.   Hence, neglecting these terms in the
transient analysis was justified.  Of course, reaction was  relevant to the
steady state analysis.  The insignificance of dispersion was also indicated
by the fact that at one pore volume C/CS was less than 0.01  for all cases.

     Analysis of phosphorus transport with the kinetic model gave good
description of both steady state and transient response.  The model predicted
a logarithmic distribution at steady state, as was observed  experimentally
both in the laboratory and the field.  Estimates of adsorption, desorption
and reaction coefficients showed that all three varied in an asymptotic manner
with velocity.  It was concluded that at lower velocities mass transfer to
the particle surface was diffusion controlled, while at higher velocities
surface kinetics was controlling.  Calculation of characteristic times showed
that dispersion was negligible compared to the other processes, which justi-
fied use of Equation (26).

PHOSPHORUS KINETICS

     Batch studies were conducted to elaborate the details  associated with
the kinetic scheme,  Equation (18), used in the kinetic model of phosphorus
transport.  Since this model assumed that phosphate molecules were adsorbed
onto a surface, then the number of adsorption sites per molecule was an impor-
tant parameter in the process.

     Various aspects of phosphorus fixation in soils were discussed previously
by Hemwall (1957), Ulrich et al_. (1962), Hsu (1964), Tandon  and Kurtz (1968),
Rajan and Fox (1972), Probert and Larsen (1972), and Kuo and Lotze (1974).

                                     155

-------
TABLE 51.   VALUES OF RATE COEFFICIENTS AND
           CHARACTERISTIC TIMES AT 2-CM DEPTH

Parameter
V
D
ka
kd
kr
cm/mi n
cm
1
1
1
2
/min
/min
/min
/min
0.
0.
1.
0.
0.
118
0122
10
031
00013
Numerical Value
0.
0.
2.
0.
0.
256
0329
00
079
00024
0.
0.
2.
0.
0.
539
0515
75
110
00039
0.
0.
3.
0.
0.
900
239
00
184
00046
16.9
328
0.91
32
7700
7.8
122
0.50
13
4200
3.7
78
0.36
9
2600
2.2
17
0.33
5
2200
                    156

-------
In all the rate studies reported, a two-stage sequence was observed—a fast
initial drop in solution phosphate followed by a slower decrease.  Probert and
Larsen (1972) concluded that the fast step resulted from exchange between
solution and solid phases, while the slower step reflected incorporation of
phosphorus into the solid phase.  Hsu (1964) concluded that the fast step
related to adsorption of phosphate onto colloidal aluminum hydroxide and iron
hydroxide in the soil and that the slow step was caused by adsorption of
phosphate onto surfaces of hydroxides and oxides which formed during the
experiment.

     Enfield and Bledsoe (1975) applied several  kinetic models in estimating
phosphorus fixing capacity of soils.

Development of the Model

     Preliminary experiments were conducted in a batch reactor with several
combinations of soil mass and initial concentration of phosphorus.  If the
kinetic model of Equation (18) was correct, then the graph of relative phos-
phorus concentration versus time should be unaffected by soil mass.  It was
observed that changing the soil mass did shift the plot; viz, that increased
soil mass in the reactor increased the rate of disappearance of solution
phosphorus.  This observation indicated that at least one step in the process
was not first order.  In fact, the results suggested that adsorption could be
described by second order kinetics.  The kinetic model adopted was (Overman
and Chu, 1977a)

                                  ka     kr
                           P + S^Z!:  A —*-  F + S                       (52)

                                  kd

where  P = concentration of phosphorus in solution
       S = concentration of adsorptive sites in the soil
       A = concentration of adsorbed phosphorus
       F = concentration of fixed phosphorus
      ka = kinetic coefficient for adsorption
      kd = kinetic coefficient for desorption
      kr = kinetic coefficient for reaction

All concentrations were expressed on a volume basis.  Equation (52) repre-
sented a case of heterogeneous catalysis, and was recognized as an example of
Langmuir-Hinshelwood kinetics (Laidler, 1950).  Adsorption was assumed to
follow second order kinetics, while desorption and reaction were assumed to
be first order processes.  For a closed batch reactor the rate of gain of
phosphorus in solution was described by


                              3T • -kasp + kdA                           <53>

Because the nonlinear nature of Equation (53) presented difficulties for
obtaining a mathematical solution, it was decided to utilize an open reactor
with a steady input of phosphorus, r.  The appropriate kinetic equations for
this reactor were:

                                     157

-------
                                = r -  kaSP + kdA                         (54)

and

                            ^=kaSP-  kdA-krA                         (55)

subject to

                                 S = SQ  -  A                              (56)


where S0 was the total  concentration of  adsorptlve  sites  in  the  reactor.
Equation (56) resulted  from the  catalytic  nature of Equation (52).

     For steady state conditions  Equations  (54) - (56)  reduced  to


                            0  =  r - kaSsPs  + kdAs
and
                            0  =  kaSsPs  -  (kd +  kr> As                     (58)
                                Ss  =  S0  = As                             (59)
where subscript s  referred  to  steady  state.  Combination of Equations  (57) -
(59) yielded


                            Ss  = 	£	                             (60)

                                 i +F-hr ps
                                      kd   Kr  s

and


                              r  = k   /k° S	                            (61)
                                  d  * ^ + P
                                     ka      s

Using the definitions

                                     k ,  + k
                                K =  -4	r-                              (62)
                                      Ka

and


                                 rm  = krSo                               (63)


                                     158

-------
Equations  (60) and  (61) were reduced to

                                        S
                                 Ss = —V                              (64)
and


                                       m s                               //-i-\
                                 r = K +  p                               (65)
                                          s

It was noted that rm was the upper limit  for r and that at P$ = K, r = rm/2.
The catalytic form of Equation  (52) led to the hyperbolic relationship between
feed rate and steady state phosphorus concentration given by Equation (65).
In fact, achievement of a steady state required that Equation (52) be cata-
lytic in nature.  Equation (65) showed the same form as the Michaelis-Menton
relationship in enzyme kinetics (Aiba et_  aj_., 1965).

Effect of Soil/Solution Ratio

     Experiments were conducted in a batch reactor at 25°C and at a pH of 5.  At
the beginning of each run a selected quantity of I^PCty was diluted to 500 ml
with deionized water, adjusted  to pH = 5  and placed in the reactor.  A
selected quantity of soil was then added  to the reactor.  During the experi-
ment a paddle stirrer kept the  soil suspended while a solution of HgPCty was
injected into the reactor at a  constant rate of 3.16 m£/hr with a syringe
pump.  The pH was controlled at 5 with a  two-way pH controller by suspending
the electrodes in the reactor.  Checks of the electrodes at the beginning and
end of each run verified their  stability.  Lakeland fine sand was collected
from the 30-60 cm depth at Tallahassee in an area which had received neither
effluent nor fertilizer.  This  soil was known to contain < 5% silt, < 5% clay
and a large amount of iron and  aluminum (Hortenstine, 1966).   Experiments
were conducted with 100, 150, 200 and 250 g soil, which had been dried at
105°C in a forced air oven for  24 hr, in  500 ml of solution.   Samples were
collected at 1/2-, 1-, 1 1/2-,  2-, 2 1/2-, 3-, 4-, 5-, and 6-hr periods and
immediately filtered through 0.45 ym Mi Hi pore filters, with prefilters to
remove larger particles, to stop the reaction and for chemical  analysis.  Ortho-
phosphate was determined by stannous chloride reduction (APHA,  1971).  It was
found in preliminary experiments that beginning with a phosphate solution in the
reactor enhanced the approach to steady state.  In all  the runs phosphate
concentration in the reactor reached steady state within 2 hr.   In several
cases, the syringe pump was stopped after 6 hr to show that phosphorus did
decay rapidly toward zero.   Volumes added by the pump or removed by sampling
were negligible.  Experiments were_conducted at pH = 5 so that  essentially
all the phosphate occurred as
     Equation (65) was used to fit the experimental data, using the weighted
statistical procedure of Wilkinson (1961).  Four rates of phosphorus addition
were used for each soil/solution ratio.  The data did follow the predicted
trends (Figure  98).  Furthermore, the upper limit increased with soil mass,

                                     159

-------
                  PS,  H  HOLE/L
Figure 98.   Effect of soil  mass on steady state phosphorus
           fixation in the batch reactor.

-------
cr>
                                                                                  2SO
                                                   M,   GH
                                  Figure 99.   Dependence on maximum phosphorus
                                              fixation  rate on soil mass.

-------
01
ro
                                                    M,  GH
                           Figure 100.  Dependence  on equilibrium constant of phosphorus
                                       fixation  on soil mass.

-------
as predicted by Equation (13).  The graph of rm versus soil mass showed a
linear increase (Figure 99 ), as predicted by Equation (63).  However, the
graph showed a nonzero intercept.  This suggested that the solution reaction
between phosphate and slightly soluble aluminum (Hsu, 1975) was significant.
At constant pH this reaction was expected to be first order in P. and inde-
pendent of soil mass.  This effect was later verified.  The equilibrium con-
stant was also shown to vary with soil mass (Figure 100).  The reason for
this was not clear and remained unexplained.

Effect of pH

     Additional steady state batch experiments were conducted to show the
dependence of rm and K on pH (Overman and Chu, 1977b ).   Experiments were
conducted at pH = 2, 3, 5, 7 and 8.  Four rates of phosphorus addition were
used at each pH.  In all runs 250 g of Lakeland fine sand was used in 500 ml
solution.  Stirring and pH control were as noted above.

     Equation (65) was again used to fit the data (Figure 101).   The analysis
gave values for rm and K at each pH.  These curves at first appeared confus-
ing, however, further analysis revealed their meaning.  Values of rm showed a
decrease with an increase in pH (Figure 102).   This trend follows that
observed by Muljadi et al_. (1966), Chen et al_. (1973), Rajan ejt al_.  (1974)
and Hsu (1975).  Hsu~Tl975) suggested that OH" competed  strongly with H2POZ
for adsorption by aluminum and iron compounds in the soil.  The graph of 1/K
versus pH showed a distribution very similar to that of the H2P04 fraction
(Figure 103).  For pH 2-8,H2P04 and HPO^ were the dominant forms of phosphate
This was interpreted to mean that ka changed with pH.   The adsorption process
was written in terms of elemental P, but Figure 103 suggested that in fact
H£P07 was the relevant phosphate ion, by assuming that k= « H2P04-   Muljadi
et. aL (1966) and Rajan et al_. (1974) also concluded that H2P04 was  the form
involved in adsorption.  The shift between distributions  in Figure 10.3
resulted from the suspension effect of a pH value of approximately 0.2 in the
batch reactor.

Effect of Solution Reaction

     In the analysis above the batch process was treated  as heterogeneous
catalysis.  Hsu (1975) showed that phosphate reacted in  solution with alumi-
num.  Consequently, Equation (54) was modified to include a first order
homogeneous reaction so that

                          dP = r _ k.p _ k sp + k.A                      (66)
                          dt              ad

where k' was the first order rate coefficient (Overman and Chu,  1977c).
Equations (55) and (56) remained the same.  For steady state conditions it
was shown that


                              r = k'p+                                 (67)
                                    163

-------
CTl
                                                M  HOLE/L
                           Figure 101.   Effect of pH on steady  state phosphorus
                                       fixation in the batch reactor.

-------
                     X
                     oc
                     I
                     N
                    o
(Ti
(jn

                                  Figure  102.   Dependence of maximum phosphorus
                                               fixation rate on pH.

-------
CTi
                     x   --
                                                      PH
                                                                                          o
                                                                                     10
                                 Figure 103.  Dependence of equilibrium constant
                                              for phosphorus fixation  on pH.

-------
where rm and K were defined as before.  Using the definition

                                r1 = r - k'Ps                             (68)

Equation (67) was written as


                                 r'-                                     (69)
 Equation  (69) was of the same form as Equation  (65), so rm and K were
 evaluated by the same procedure as before.

     Values of k1 were chosen until the plot of rm versus soil mass passed
 through the origin.  With k' = 0.003/hr the graph was linear and passed
 through the origin.  This result conformed with Equation (63), since the cor-
 relation  between S0 and soil mass was expected to be linear with a zero
 intercept.  The correlation between r and P5 (Figure 104) was described very
 well by Equation (67).  These curves did not approach maxima because of the
 homogeneous reaction, which continued to increase with Ps.

 Summary

     The  kinetics of phosphorus fixation was studied in a batch reactor
 operated  in the steady state mode.  A kinetic model was developed which in-
 cluded both heterogeneous and homogeneous processes.  Langmuir-Hinselwood
 kinetics was used to describe the heterogeneous process, while the homogeneous
 component employed first order kinetics.  Results from the steady state
 experiments agreed with the assumption of heterogeneous catalysis.  Apparently
 adsorptive sites in the soil acted to catalyze chemical reaction between
 phosphate and some other component.  Results at different pH values identified
 ^04 as  the pertinent phosphate ion involved in the heterogeneous step.  The
 expected  linear correlation between the maximum rate of surface reaction and
 soil was verified.

     Dependence of phosphorus fixation on pH and soil mass was explained very
 well with the proposed kinetic model.  It did not estimate phosphorus fixation
 capacity of soil.  The very difficult task of identifying the chemical  mecha-
 nism was not achieved in this study.

     In the model for phosphorus transport, the kinetic component assumed
 first order kinetics, given by Equation (19).  This assumption was justified
 in the packed-bed reactor since an excess of adsorptive sites was present and
 the number of adsorbed molecules was very small compared to the number of
 sites.  For this reason the second order process reduced to pseudo first
 order.

 CATION TRANSPORT

     In the effluent irrigation system cation exchange was important in pro-
 cesses such as nitrification (NH^-^NO^) and nutrient uptake by plants,  A
model of cation transport was utilized to establish coupling between ion

                                     167

-------
                                        4—I—  I     \
CT)
OO
                                          Ps,  M  HOLE/L
                          Figure 104.  Effect of solution reaction on steady state
                                      phorphorus fixation in a batch reactor.

-------
exchange and convection.  Components of the model included convection, dis-
persion and cation exchange.  Measurements were made on a univalent/univalent
system.  The cations K+ and NH| were chosen because of their similar ionic
mobilities.

Cation Exchange Model

     A reversible ion exchange model was assumed for the univalent-univalent
system (Hiester and Vermuelen, 1952)


                                      kc
                            C + B • S —^ C - S + B                       (70)

                                      kB

where    C = solution concentration on the inflow cation
         B = solution concentration of the outflow cation
       C-S = surface concentration of the inflow cation
       B-S = surface concentration of the outflow cation
         k = exchange coefficient

and the subscript refers to the appropriate cation.   Cation exchange was
assumed to be controlled by mass action, so that the kinetic equation


                        8C'S   k,C (B-S) - kDB (C-S)                     (71)
                         Bt

was used, where t was the time.  The analysis was simplified by assuming
constant and uniform ionic strength throughout the experiments, so that,  by
electrical neutrality

                            B + C = A = constant                         (72)

where A was the solution concentration of anion.  It was further assumed  that
the cation exchange capacity of the soil, Q, was constant,  so that

                                B-S + C-S = Q                            (73)

and

                                 B + C = C0                              (74)


where C0 was the feed concentration of the cation.  Combination of Equations
(71) - (74) yielded


                      |9- = kcC (Q - q) - kB (C0 - C) q                   (75)


where q = C-S.   The initial condition was

                             q = 0     at t = 0                          (76)
                                     169

-------
2 > 0
z = 0
Z + oo
C = 0
C = C0
C + 0
t = 0
t A 0
t J> 0
Solution of Equation  (75) required  an  auxiliary  relationship of some type.
For the packed-bed reactor this  consisted  of  a mass  balance for the cation in
the solution phase.

Cation Transport Model

     A dispersed flow model  (Smith,  1970)  was used  for the packed bed reactor,
and for one dimensional flow was written as


                        n 32C    v 3C _ 3C   p  3 (OS)                     /77x
                        UT7?3z~3t   e    3t                       U/j
                          oZ

with the conditions

                                                                          (78)

                                                                          (79)

                                                                          (80)

where  z = depth in the reactor
       D = pore dispersion coefficient
       V = pore velocity
       p = bulk density of soil
       e = porosity.

In the analysis C'S was written as mass of cation/mass  of  soil.   Equations
(75) - (80) constituted the system to be solved.  However,  it was  convenient
to convert the system to dimensionless form with the definitions

                 r* = —     n* - 3.     7* - z.     +*  _  vt
                 L*    />      M  """ ^     ^    /i      L"~rt
                      C0     H    Q          £           I


                n - A     a - &kcCo     a - .Pi    K  - kc
                I    n      (-*             P ~~  ~r-      r\  ~ 1
                    VV           V           f~[           K
                    ™ v           V           C-\t          r\r\
                                               0           B

where 1 was a characteristic length.  Equations  (75) -  (80) were  converted to


                         n 32C* _ 3C* = 3C^ +    3qj^                       (81)
                           3z*    3z

with

                                                                          (82)

                                                                          (83)

                                                                          (84)


                                     170
z*
.z*
z*
> 0
- 0
-V OO
C* =
C
C
* =
* -V
0
1
0
t*
t*
t*
= 0
^ 0
n 0

-------
and
                       = a[C* (1 - q*) - 1 (] - C*) q* ]                (85)
with

                       z* > 0      q* = 0      t* = 0                    (86)

For the special case of symmetric exchange (kr = kR = k), Equation (85)
reduced to                                   L    b


                                   a[C* - q* ]                          (87)

     Equations (81) - (86) were solved by finite differences, using the Crank-
Nicolson implicit procedure (Gupta and Greenkorn, 1973).

Response Curves

     Experiments were conducted in a packed-bed reactor, 4.8 cm ID and 10 cm
in length.  The end plates were grooved to provide more uniform flow at the
ends.  After drying in a forced air oven at 105°C for 24 hr, Lakeland fine
sand was packed in the reactor to a bulk density of 1.66 g/crn3 and porosity
of 0.376.  After purging with C02 to displace insoluble gases, the reactor
was saturated with deionized water.  Several  pore volumes of 1 N NH^l were
passed through to saturate the exchange complex with NHj ions.  This was
followed by several pore volumes of Nh^Cl solution of appropriate feed con-
centration and pH = 6.5.  Flow rates were controlled with a peristaltic pump
with speed control.  Whole discrete outflow samples were collected with a
fraction collector.  Samples were analyzed for NH4 by spectrophotometer, K
by flame photometer and Cl~ by coulometric titration.  Experiments were con-
ducted by switching between KC1 and NH^Cl of the same molar concentration
and at pH = 6.5.  Measurements of Cl~ showed that its concentration remained
constant throughout a run.  Measurements of the two cations established that
Equation (74) was satisfied.

     Output curves were all of the type shown in Figure 105.  The amount of
cation in exchange was estimated from a mass  balance for the particular
cation; viz,

            In + Pores (initial) = Out + Pores (final) + Exchange        (88)

Mass 1n (moles) was calculated from feed concentration (moles/£), flow rate
(cnr/min) and total time (min).  Mass-out was calculated from concentration
(moles/Jl) for the fraction, flow rate (cm3/min) and time between fractions
(min), and summing over all fractions.  Mass  in the pores was calculated from
concentration (moles/&) and pore volume (cm3).  Exchange quantity was divided
by soil mass in the reactor to obtain Q (meq/100 g).  Values were averaged
for the inflow and outflow cations to obtain a value of 0 for use in the model
In all cases inflow and outflow values were within 10% of each other. + In the
analysis, exchange was assumed to be symmetric (k^ = kg = k), since NH4 and K+

                                     171

-------
IV)
                                              C0 = 0.00983 IMOLES/L
                                               V = 0. 117  CH/MIN
                                                                            30
                                              VT/L
                        Figure 105.  Typical  outflow curves for NH./K  transport
                                   in a packed bed reactor.

-------
both had the same Ionic diffusion coefficients, and Equation (87) was used.
Values for k and D were chosen to obtain good agreement between data and the
model.  It was observed that the influence of dispersion was primarily limited
to the early portion of the curves.  Exchange, on the other hand, influenced
the entire curve.  Reversal of the cations with the same feed concentration
and velocity gave curves which superimposed throughout the runs, which showed
that exchange between NHj and K+ was symmetric.

Coupling of D and k with V

     Response curves for a feed concentration of C0 -  0.01 moles/£ and veloc-
ities of 0.147, 0.297 and 0.588 cm/min all followed the shape of Figure 105,
and superimposed very closely over most of the curve.   The early portions
disagreed slightly.  A graph of the parameters showed that k versus V was
linear, while D versus V was quadratic (Figure 106).  These correlations
explained the superimposition of the three output curves over the upper
portions.

     The coupling between k and V was explained with elementary film theory
(Smith, 1970).  In the above analysis, Equation (71) was written as a global
model, where solution concentrations represented bulk solution.   Apparently
the transfer from bulk solution to the particle surface was diffusion limited,
so that solution concentration adjacent to the surface was lower than bulk
concentration.  For this system surface kinetics was fast compared to diffu-
sion.  This agreed with observations in a batch reactor where the character-
istic time was found to be less than one minute, which established that sur-
face kinetics of exchange was very fast.  The diffusion limited transfer in
the packed-bed reactor caused a lag between surface and solution phases
(Figure 107).  Lag was independent of velocity, due to linear coupling between
convection and cation exchange.

Feed Concentration and System Response

     Behavior of the response curves was strongly influenced by feed concen-
tration (Figure 108).  At low concentrations response  time was  governed by
exchange, while at high concentrations convection and  dispersion were the
controlling processes.  This behavior was inherent in  the coupling between
Equations (81) and (87).

     Ionic strength had a major influence on the exchange coefficient (Figure
109).  The decrease in the exchange coefficient with increased  ionic strength
probably resulted from compression of the electric double layer at the charged
particle/solution interface (Gast, 1977), which increased the concentration
gradient near the particle surface.  This increased diffusion showed up as  an
increased exchange coefficient in the global model.

     Cation exchange capacity increased with ionic strength (Figure 109).
Melendez (1976) showed that this type of correlation was associated with
colloids of metal oxides and hydroxides which possessed surfaces of constant
potential rather than surfaces of constant charge.  Hortenstine (1966) showed
that Lakeland fine sand contained large quantities of aluminum and iron
compounds.

                                     173

-------
8
                      V,   CH/HIN
Figure 106.  Dependence of exchange and dispersion  coefficients
            on velocity for NH^/K+ transport.

-------
                            I     I     1      I     1
fr—   i     i
01
                                               Co •  0,00983  HOLiS/L
                                                                              10
                       Figure  107.  Lag between  surface and solution concentration
                                   for NHJ/K+ transport.

-------
                                   0.00983
                                   0.00499
                                   0,00131
                    VT/L
Figure 108.   Effect of feed concentration on  outflow
            curves for NH^/K  transport.

-------
O'
             ,01
02
                      C0,
Figure 109.   Effect of ionic strength  on exchange coefficient and
             cation exchange capacity  for NHt/K  transport.

-------
Summary

     A transport model  for the simple case of NH./K  was developed using the
one dimensional  dispersed flow equation and a reversible second order kinetic
equation for exchange.   For these two cations exchange was shown to be sym-
metric.  The model  described output curves very well  for all  feed concentra-
tions and velocities.   Coupling between the dispersion coefficient and veloc-
ity was shown to be quadratic, so that dispersion assumed greater importance
at higher velocities.   Dependence of the exchange coefficient on velocity was
linear, which indicated that exchange was limited by  diffusion of cations to
and from the particle  surface.  Batch measurements verified that surface
kinetics was fast compared to mass transfer in solution.  These results sug-
gested that exchange of cations such as NHj and K+ under field conditions
was closely related to  convection, i_._e, during irrigation exchange rates
increased and then  slowed down after irrigation ceased and water percolation
rate diminished.

     Several effects of feed concentration were noted.   At low concentrations
response time was controlled by exchange, while at high concentration dis-
persion became more important.  The role of feed concentration resulted from
the second order kinetics of exchange.   The exchange  coefficient decreased
with increased ionic strength, due to compression of  the electric double
layer.  Cation exchange capacity increased with ionic strength due to the
presence of colloids of aluminum and iron in Lakeland soil.   Even for this
apparently simple system of NHj/K+ exchange, there was  a complex interplay of
several factors  in  the  system.

     From these  studies on cation transport and exchange it was concluded
that nitrification  (bacterial  conversion of exchangeable NH4  to NO^ )  would
be enhanced with higher solution concentration of NHt and in  soils with higher
cation exchange  capacity.  This suggested that nitrogen uptake by the crops
at Tallahassee was  limited by the low cation exchange capacity of Lakeland
fine sand (less  than 5  meq/100 g) and that it was lower for  the effluent
used (total  N <  40  mg/£)  than would have occurred with  effluent of higher N
concentration.
                                     178

-------
                                 SECTION 8

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                                     185

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                                 APPENDIX A

                RESULTS FOR CROP YIELDS AND NUTRIENT RECOVERY
INTRODUCTION
     Detailed results for the various  crops  and years  are presented in this
appendix because of the voluminous  amount of data.   Results  are presented by
years due to commonality of wastewater characteristics and cultural practices.
A summary of results by crops is  presented in Section  6 to relate data from
different years.  In this report, mton is used to denote metric tons,  as
distinguished from English tons,  to minimize confusion.  For each year the
crop varieties are listed since yields and chemical  composition may vary
widely among varieties of the same  crop.

1971 SUMMER CROPS

     The two crops used were sorghum x sudangrass (Asgrow Grazer-S) and kenaf
(Everglades 41).  Following plowing and disking, the plots (30 m x 30  m)  were
planted in 0.9 m (3 ft) rows, with  a seeding rate of 11 kg/ha (10 Ib/acre).
Planting and harvesting followed  the schedule shown  in Table A-l.   Irrigation
rates were 25, 50, 100 and 200 mm/week.  Green weights were  measured for  each


                 TABLE A-l.  FIELD  SCHEDULE  FOR SUMMER 1971

Operation
Planting
Crop
Sorghum x sudangrass
4/7/71

Kenaf
4/9/71
       Harvesting
          1st                             6/16/71             6/16/71
          2nd                             8/25/71             9/27/71
plot by collecting all  the vegetation.   From each batch 1  kg composite samples
were taken, dried in a  forced air oven  at 70°C for 24 hr,  weighed again and
ground in a Wiley mill.   Duplicate 1  g  samples were analyzed for Kjeldahl-N
(USEPA, 1971).   Other nutrients were  measured from 0.5 g samples digested in
15 ml HNO^ and  10 ml HC10*, made up to  50 ml with deionized water.  Chemical
analyses included P by  SnC^ (APHA, 1971), K and Na by flame emission, and all
others by atomic absorption.  Effluent  samples were analyzed by the same
methods.


                                     186

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     Chemical characteristics of the effluent were measured weekly on compos-
ite samples.  Average values for the period 4/71-9/71 are shown in Table 6.
Effluent pH averaged 7.6 while nitrogen composition was 74% Nhty-N, 13% N03-N
and 13% organic N.  Since these samples were not analyzed for P, K, Ca, Mg,
and Na, values for the period 4/72-9/72 were used.

Sorghum x Sudangrass

     The crop showed positive response to effluent irrigation.  Yields of
green forage as well as dry forage showed an increase with application rate,
as shown in Table A-2.  Dry matter content remained essentially constant, for
TABLE A-2.
YIELD AND
DRY MATTER
OF SORGHUM
X
SUDANGRASS -
1971

Rate

mm/week

25

50
1

st
100
Harvest
200

   Green Weight, mtons/ha
   Dry Matter, %
   Dry Weight, mtons/ha
   Green Weight, mtons/ha
   Dry Matter, %
   Dry Weight, mtons/ha
23.7
21.2
 5.04
18.6
21.9
 4.08
26.9
18.1
 4.86
32.9
18.8
 6.18
                                                 2nd Harvest
23.7
23.6
 5.60
25.3
21.7
 5.49
39.9
20.4
 8.13
31.4
23.3
 7.28
                                                    Net
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
42.3
21.5
9.12
50.6
20.7
10.46
58.2
20.0
11 .67
71.3
21.6
15.41

an average composite value of approximately 21%.   These  results  compare
closely with fertility trials in Gainesville,  Florida (Agronomy  Mimeo  Report,
1971) with this same variety where 228 kg/ha of applied  N  produced  58.8
mtons/ha.

     By combining dry yields (Table A-2)  and nutrient composition  (Table  A-3),
crop uptake of the various elements was calculated (Table  A-4).  Nutrient
uptake of all  elements (except Fe and Zn)  showed an increase with  irrigation
rate.  A positive correlation between uptake and application rate  of nutrients
may be seen from Table A-4.  All of these  illustrated the  response  of  dimin-
ishing returns, i.e. succeeding increments of nutrient applied  produced
smaller and smaller increments~of uptake.   This in turn  led to  decreasing
efficiency of recovery.  Figure A-l illustrates these features  for  nitrogen.
For example, an irrigation rate of 25 mm/week (1  in./week) provided 88 kg/ha N
                                    187

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TABLE A-3.   NUTRIENT COMPOSITION  OF  SORGHUM  X  SUDANGRASS  -  1971

Rate mm/week

N
P
K
Ca %
Mg
Na
Fe
Zn

N
P
K
Ca %
Mg
Na
Fe
Zn

N
P
K
Ca %
Mg
Na
Fe
Zn
25

0.89
0.42
0.29
0.39
0.53
0.16
0.0091
0.0037

1.04
0.75
0.98
0.50
0.57
0.18
0.0380
0.0041

0.96
0.57
0.60
0.44
0.55
0.18
0.0220
0.0039
50
1st
0.94
0.67
0.43
0.46
0.67
0.21
0.0065
0.0038
2nd
1.14
0.80
1.12
0.50
0.64
0.10
0.0140
0.0053

1 .05
0.74
0.80
0.48
0.65
0.15
0.0105
0.0045
100
Harvest
0.86
0.54
0.26
0.46
0.72
0.12
0.0100
0.0026
Harvest
1.50
1.00
0.96
1.55
0.95
0.36
0.0200
0.0097
Net
1.17
0.67
0.59
0.97
0.83
0.23
0.0147
0.0059
200

1.30
0.76
0.21
0.77
1.01
0.19
0.0390
0.0054

1.20
0.66
0.85
0.58
0.65
0.15
0.0130
0.0042

1.25
0.71
0.51
0.68
0.84
0.17
0.0195
0.0048
                              188

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45
21
15
20
27
9.0
0.46
0.19
46
33
21
22
33
10.2
0.31
0.18
54
33
16
28
44
7.4
0.62
0.16
105
62
17
63
82
15.5
3.17
0.44
	TABLE  A-4.   NUTRIENT  UPTAKE  BY  SORGHUM X  SUDANGRASS  -  1971


 Rate       mm/week	25	50	1_00	200

                                          1st Harvest

  N
  P
  K
  Ca         kg/ha
  Mg
  Na
  Fe
  Zn

                                          2nd Harvest

  N                        43          64           83          87
  P                        31           45           55          48
  K                        40          63           53          62
  Ca         kg/ha          20          28           85          42
  Mg                       23          36           52          47
  Na                       7.4          5.6         19.7        11.0
  Fe                       1.54         0.78         1.10        0.95
  Zn                       0.17         0.29         0.53        0.30

                                            Total

  N
  P
  K
  Ca         kg/ha
  Mg
  Na
  Fe                       2.00         1.09         1.72        4.12
  Zn                       0.36         0.47         0.69        0.74
88
52
55
40
50
16.4
110
78
84
50
69
15.8
137
88
69
113
97
27.1
192
no
79
105
129
26.5
                                  189

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UD
O
                                                                               o
                                        N
                       Figure  A-l.   Nitrogen recovery by sorghum x sudangrass.

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     TABLE A-5.   NUTRIENT RECOVERY  BY  SORGHUM  X  SUDANGRASS  -  1971

Rate      mm/week	25	50	TOO	200

                                       Harvested,  kg/ha

 N                        88           110           137          192
 P                        52            78           88          110
 K                        55            84           69          79
 Ca                       40            50           113          105
 Mg                       50            69           97          129
 Na                       16.4          15.8         27.1        26.5

                                       Applied,  kg/ha

 N                        88           175           350          700
 P                        42            85           170          340
 K                        21            42           85          170
 Ca                      112           225           450          900
 Mg                       31            62           125          250
 Na                      122           245           490          980

                                        Recovered,  %

 N                       100            63           39          27
 P                       120            92           52          32
 K                       260           200           81          46
 Ca                       36            22           25          12
 Mg                      160           110           78          52
 Na                       13.0          6.4          5.5          2.7
                                 191

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with a corresponding uptake of 88 kg/ha N,  for a recovery efficiency of 100%,
Increasing the application rate to 50 mm/week (2 in./week) raised the values
to 175 kg/ha N applied,  110 kg/ha harvested and 63% recovery.

     From Table A-5 it appears that most elements were supplied in adequate
quantity in the effluent.   The major exception to this was K.   At 25 mm/week
recovery was 260%.   For  a  soil low in available K, as  Lakeland fine sand is,
a deficiency of K could  eventually occur.   Supplemental  K might then be
required.  It has been pointed out that effluent is deficient  in K for pro-
ducing forage crops (Kardos,  et_ al_.,  1974).

     It should be pointed  out that response of a crop  to added nutrients
depends upon nutrient reserves in the soil.   From this work, Overman and Evans
(1978) estimated soil  reserves of N,  P and  K of 56, 45 and 45  kg/ha, respec-
tively.  Such values do  not seem unusual, since the plots had  carried a grass
cover under irrigation with effluent (no grass removal)  for five prior years.
However, under crop harvest,  these reserves  of N and K would likely diminish.

     In normal practice, two  or three harvests of sorghum x sudangrass would
be expected.   A third  harvest failed  for lack of weed  control.

Kenaf

     Yield results  are shown  in Table A-6.   Both green and dry yields
increased with irrigation  rate,  while dry matter content decreased slightly.
These results agreed closely  with fertility trials in  Gainesville, Florida
(Pepper and Prine,  1969) with this variety,  where 190  kg/ha N  applied produced
11 mton/ha of oven  dry material.

              TABLE A-6.   YIELD AND  DRY MATTER OF KENAF  - 1971

Rate
mm/ week
25
50 100
200
1st Harvest
   Green Weight,  mtons/ha
   Dry Matter,  %
   Dry Weight,  mtons/ha
   Green  Weight,  mtons/ha
   Dry Matter,  %
   Dry Weight,  mtons/ha
   Green Weight,  mtons/ha
   Dry Matter,  %
   Dry Weight,  mtons/ha
19.7
15.0
 2.96
27.8
28.0
 7.77
47.5
22.6
10.7
28.4
13.9
 3.94
29.6
15.3
 4.52
                                                 2nd  Harvest
30.5
25.6
 7.80
                                                    Net
58.9
19.9
11.7
30.7
22.6
 6.92
60.3
19.0
11.4
39.6
16.9
 6.70
40.1
19.2
 7.71
79.7
18.1
14.4
                                     192

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TABLE A-7.   NUTRIENT COMPOSITION OF KENAF -  1971

Rate

N
P
K
Ca
Mg
Na
Fe
Zn

N
P
K
Ca
Mg
Na
Fe
Zn

N
P
K
Ca
Mg
Na
Fe
Zn
mm/ week 25

1.49
0.90
0.28
% 1.91
1.02
0.28
0.0150
0.0049

0.74
0.74
0.86
% 1.38
0.75
0.22
0.0120
0.0076

0.94
0.78
0.70
% 1.52
0.82
0.24
0.0128
0.0069
50
1st
1.46
0.78
0.27
1.60
0.92
0.25
0.0170
0.0044
2nd
0.90
0.80
0.93
1.49
0.85
0.25
0.0140
0.0082

1.09
0.79
0.71
1.53
0.87
0.25
0.0150
0.0069
100
Harvest
1.34
0.86
0.28
1.70
1.02
0.33
0.0150
0.0059
Harvest
1.06
0.88
1 .25
1.40
0.85
0.40
0.0200
0.0094
Net
1.16
0.87
0.96
1.52
0.92
0.37
0.0180
0.0080
200

2.73
0.68
0.24
1.76
0.96
0.24
0.0250
0.0039

2.34
0.62
3.62
2.22
0.82
0.23
0.0340
0.0064

2.52
0.65
2.05
2.01
0,88
0.23
0.0300
0.0052
                      193

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TABLE A-8.   NUTRIENT UPTAKE BY KENAF - 1971

Rate

N
P
K
Ca
Mg
Na
Fe
Zn

N
P
K
Ca
Mg
Na
Fe
Zn

N
P
K
Ca
Mg
Na
Fe
Zn
mm/week 25

44
27
8
kg/ha 56
30
8.3
0.45
0.15

57
57
67
kg/ha 107
58
17.1
0.93
0.59

101
84
75
kg/ha 163
88
25.4
1.38
0.74
50

57
31
11
63
36
9.
0.
0.

71
62
72
116
66
19.
1.
0.

128
93
83
179
102
29.
1.
0.
100
1st Harvest
60
39
13
77
46
9 14.9
67 0.67
17 0.27
2nd Harvest
73
61
97
97
59
5 27.7
09 1.39
64 0.65
Total
133
100
no
174
105
4 42.6
73 2.06
81 0.92
200

183
46
16
118
64
16.1
1.68
0.26

180
48
279
171
63
17.7
2.62
0.49

363
94
186
289
127
33.8
4.30
0.75
                   194

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TABLE A-9.  NUTRIENT RECOVERY BY KENAF - 1971

Rate mm/week

N
P
K
Ca
Mg
Na

N
P
K
Ca
Mg
Na

N
P
K
Ca
Mg
Na
25

101
84
75
163
88
25.4

106
52
26
138
39
151

95
160
290
120
220
17.0
50
Harvested,
128
93
83
179
102
29.4
Applied,
212
103
52
275
78
302
Recovered
60
90
160
65
130
9.7
100
kg/ha
133
100
110
174
105
42.6
kg/ha
425
206
103
550
157
605
01
, h
31
48
no
32
67
7.0
200

363
94
186
289
127
33.8

850
412
206
1100
314
1210

43
23
140
26
41
2.8
                    195

-------
                    IRRIGATION  RflTE,  HM/WEEK
01
                                                         1000
                           N  flPPLI
                      Figure A-2.  Nitrogen recovery By kenaf - 1971

-------
     Combination of dry yields (Table A-6) and nutrient composition (Table
A-7) provided estimates of nutrient uptake (Table A-8).  Increased application
of all nutrients led to increased uptake.   Recovery efficiency (Table A-9,
Fig. A-2) decreased with application rate  for all elements measured.   As with
sorghum x sudangrass, a K deficiency may occur under extended periods of low
irrigation rates (<50 mm/week).   Overman and Evans (1978)  estimated soil
reserves of N, P and K of 56, 73 and 56 kg/ha, respectively, which agrees
reasonably well with the values  estimated  from the sorghum x sudangrass data.
Under continuing harvest, these  reserves of N and K would  be depleted.

     Potential uses for kenaf have been discussed by Killinger (1967, 1969).

1971 WINTER CROPS

     Rye (Wrens Abruzzi) and ryegrass (Florida Rust Resistant)  were selected
for winter crops.  Earlier attempts with oats failed,  apparently  due  to
disease problems.  All plots were disked,  plowed and disked again.   Both crops
were drilled at a rate of 1.7 hl/ha (2 bu/acre)  on October 22~  1971.   Plots
were harvested in January 1972,  but data was invalid due to malfunction of a
weighing device.  Plots were harvested again March 17, 1972.  Green weights
were recorded and 0.5 kg composite samples collected and dried  at 60°C.  All
other procedures were the same as for the  summer crops. Crop growth  was quite
vigorous.

     Effluent values from Table  6 were used for  the period 10/71-3/72.
Missing values were approximated as those  of 4/72-10/72.

Rye

     Results in Table A-10 show  that green and dry yields  increased with
irrigation rate, while dry matter content  decreased,  i.e.  higher  irrigation


  	TABLE A-10.   YIELD AND COMPOSITION OF RYE -  1971	

   Rate         mm/week           6         12         25         50
Green Weight, mtons/ha
Dry
Dry
N
P
K
Ca
Mg
Na
Fe
Zn
Matter, %
Weight, mtons/ha



%




6.97
19.3
1.35
4.21
0.68
2.80
0.52
0.23
0.28
0.110
0.0092
8.11
19.0
1.54
4.61
0.69
2.88
0.49
0.24
0.25
0.067
0.0095
11.8
17.1
2.02
4.62
1.05
2.80
1.15
0.46
1.40
0.020
0.0067
15.3
14.7
2.24
4.79
0.94
3.10
1.02
0.43
0.35
0.032
0.0170
                                     197

-------
produced forage of higher moisture content.   Nitrogen content of the rye was
quite high, since it was harvested in the dough stage after seed head forma-
tion, and showed an increase with irrigation rate.   Again,  the curve of
diminishing returns is well  illustrated by this data (Table A-ll).   Due to
the low application rates, efficiency of recovery was quite high, where H
recovery exceeded 100% (Fig. A-3) for all rates.  The likelihood of K
deficiency is strongly indicated here, since recovery exceeded 100%.
   Rate
               TABLE A-ll.  NUTRIENT RECOVERY BY RYE - 1971
mm/week
12
25
 50
    N
    P
    K
    Ca
    Mg
    Na
    N
    P
    K
    Ca
    Mg
    Na
                                         Harvested,  kg/ha
              57
               9
              38
               7
               3,1
               3.8
              12
               6
               3
              16
               5
              18
71
11
44
 8
 3.7
 3.8
93
21
57
23
 9.3
 2.8
                                          Applied,  kg/ha
25
12
 6
32
 9
35
50
24
12
65
18
70
                                           Recovered,
108
 21
 70
 23
  9.6
  7.8
100
 48
 24
130
 36
140
N
P
K
Ca
Mg
Na
470
150
1200
43
67
21
290
88
730
23
40
11
190
88
470
36
50
4
no
44
290
18
26
5

Ryegrass

     Green and dry yields of ryegrass (Table A-12)  also showed a positive
response to irrigation, with dry matter content showing a sizable decrease.
At 50 mm/week the forage was very wet (89% water).   Also, the N content was
somewhat lower than for rye.  In fact,  nutrient recovery was  lower for rye-
grass (Table A-13) than for rye, in spite of the higher yields.  Efficiency
of N recovery decreased rapidly with irrigation rate (Fig.  A-4), but remained
quite high.
                                     198

-------
                             HM/HEEK
cc
I
LU
cr
               25          50

            N flPPLIED,  KG/Hfl
                                       50b
      Figure A.-3.  Nitrogen recovery by Rye - 1971,
                    199

-------
TABLE A-12.   YIELD AND COMPOSITION OF RYEGRASS - 1971

Rate mm/week
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
N
P
K
Ca %
Mg
Na
Fe
Zn
6
11.8
20.1
2.38
1.97
1.06
3.18
1.10
0.45
0.72
0.028
0.0125
12
10.7
18.5
1.98
2.03
1.00
2.78
1.12
0.44
1.15
0.021
0.0091
25
12.9
16.3
2.11
2.35
0.77
2.82
0.74
0.34
1.28
0.042
0.0158
50
21.0
11.0
2.31
2.75
1.17
2.08
0.95
0.32
1.50
0.015
0.0036

  TABLE A-13.   NUTRIENT  RECOVERY  BY  RYEGRASS  -  1971

Rate mm/week

N
P
K
Ca
Mg
Na

N
P
K
Ca
Mg
Na

N
P
K
Ca
Mg
Na
6

47
25
76
26
10.7
17

12
6
3
16
5
18

380
420
2500
160
230
97
12
Harvested,
40
20
55
22
8.7
23
Applied,
25
12
6
32
9
35
Recovered
160
160
900
68
95
63
25
kg/ha
50
16
59
16
7.2
27
kg/ha
50
24
12
65
18
70
, %
100
67
490
24
39
38
50

64
27
48
22
7.4
35

100
48
24
130
36
140

65
56
200
17
20
24
                         200

-------
IN3
O
                                 Figure A-4.  Nitrogen recovery by  ryegrass  -  1971,

-------
1972 SUMMER CROPS

     Crops included sorghum x sudangrass (Asgrow Grazer-S), kenaf (Everglades
41), corn (McNair 440 V for silage and Pioneer 3369  A  for grain), and pearl
millet (Tiflate).  All plots were disked, plowed and disked again.  Planting,
cultivation and harvests followed the schedule in Table A-14.   All crops were
                 TABLE A-14.  FIELD SCHEDULE FOR SUMMER 1972

Crop
Sorghum x sudangrass
Kenaf
Corn Silage
Corn Grain
Pearl Millet
Planting
3/23/72
3/23/72
3/23/72
3/23/72
4/13/72
Cultivation
4/27/72
6/8/72
4/27/72
4/27/72
4/27/72
4/27/72
Harvesting
6/7/72
7/27/72
9/26/72
7/7/72
6/21/72
9/7/72
7/3/72
9/28/72

planted in 0.9 m (3 ft) rows with a length of 30 m (100 ft).   Four rows  of
pearl  millet  were planted and harvested,  with weights  being  recorded  for  the
inner two rows, only.   All other plantings contained  14 rows.   Seeding rates
were as follows:  sorghum x sudangrass  -  11  kg/ha, kenaf -  11  kg/ha, corn
silage - 11  kg/ha, corn grain - 17 kg/ha,  and pearl millet  -  11  kg/ha.   Ana-
lytical procedures followed those outlined above for  the 1971  summer crops.

     Duplicates of each crop (except pearl millet) were planted, and each
irrigation rate was duplicated so that  single and split application could  be
made to compare crop yields and nutrient  uptake under the two methods.   Split
applications were made as outlined in Table A-15.  Results  for these studies
have been discussed elsewhere (Overman, 1975 and Overman, 1978).

     Chemical  characteristics of the effluent for the period  4/72-9/72 are
shown in Table 6.  Irrigation rates were  50, 100, 150 and 200 mm/week.

Sorghum x Sudangrass - Single Applications

     Three harvests were made.   Yields  for the third  cutting  were lower due
to decreased solar radiation and temperature during this period of the year
(Table A-16).   Both green and dry weights  increased with irrigation rate,
while dry matter content remained essentially constant.  The  third harvest
also showed  slightly lower nitrogen (protein) content than  the other two
                                     202

-------
          TABLE A-15.   SCHEDULE FOR SPLIT APPLICATIONS*

Rate
mm/week
50
100
150
200
Applications
per week
1
2
3
4
Irrigation
days
Wed.
Tues. , Thurs.
Mon. , Wed. , Fri .
Mon., Tues., Thurs., Fri.

* Each increment included 50 m application.
    TABLE A-16.   YIELD AND DRY  MATTER  OF  SORGHUM  X SUDANGRASS
                 WITH  SINGLE  APPLICATIONS -  1972

Rate

mm/week

Green Weight
Dry Matter,
Dry Weight,


Green Weight
Dry Matter,
Dry Weight,


Green Weight
Dry Matter,
Dry Weight,


Green Weight
Dry Matter,
Dry Weight,


, mtons/ha
%
mtons/ha


, mtons/ha
%
mtons/ha


, mtons/ha
of
h
mtons/ha

5
"/
la
ml

mtons/ha
tons/ha
50

27.
16.
4.

28.
19.
5.

5.
25.
1.

61.
18.
11.


8
2
50

7
1
49

3
0
34

8
3
3
100

27
15
4

41
18
7

21
23
4

89
18
16

1st
.3
.7
.30
2nd
.0
.7
.66
3rd
.6
.0
.97

.9
.9
.9
150
Harvest
31.
16.
5.
Harvest
32.
18.
6.
Harvest
25.
25.
6.
Net
88.
19.
17.


1
6
17

7
8
14

1
0
27

9
7
6
200

34
16
5

35
18
6

25
23
6

95
18
18


.3
.0
.49

.6
.4
.56

.8
.5
.05

.7
.9
.1
                               203

-------
ro
o
                o
                o
     IRRIGATION  RfiTE,  HM/MEEK

0         SO         100        ISO        2
                      —  I     I —
              X o
              "x.
              o
               *,
             O
to
UJ

oc
CE
                  0
                                         I
                        E HflRVESTED
                 800      1200

            N  flPPLSEO,  KG/Hfi
                                                      •I	!•
                                             -.  Q
                                                 UJ
                                                 oc
                                             j_o yj
                                                » >
                                                 o

                                                 yj
                                                   O
                                                 2000
                Figure A-5.  Nitrogen recovery by sorghum x sudangrass with single
                          applications -  1972.

-------
         TABLE A-17.  NUTRIENT COMPOSITION OF SORGHUM X SUDANGRASS
	WITH SINGLE APPLICATIONS - 1972	


Rate	mm/week	50	100	150	200

                                              1st Harvest

N                               1.46        1.91          2.12         1.95
P                               0.43        0.44          0.38         0.37
K                               1.06        1.15          1.04         0.96
Ca               %              0.62        0.61          0.72         0.62
Mg                              0.55        0.80          0.76         0.58
Na                              0.018       0.020         0.025        0.035
Fe                              0.015       0.045         0.064        0.014

                                              2nd Harvest

N                               1.90        1.94          1.68         1.71
P                               0.44        0.33          0.29         0.32
K                               0.78        0.82          0.92         1.00
Ca               %              0.60        0.49          0.52         0.64
Mg                              0.59        0.64          0.70         0.75
Na                              0.030       0.035         0.032        0.035
Fe                              0.019       0.023         0.029        0.040

                                              3rd Harvest

N                               1.59        1.51          1.52         1.61
P                               0.39        0.29          0.28         0.27
K                               0.90        0.83          0.80         0.80
Ca               %              0.65        0.47          0.47         0.43
Mg                              0.49        0.44          0.48         0.52
Na                              0.033       0.030         0.030        0.025
Fe                              0.020       0.015         0.020        0.036

                                                   Net

N                               1.69        1.81          1.75         1.75
P                               0.42        0.35          0.32         0.32
K                               0.91        0.91          0.91         0.92
Ca               %              0.61        0.52          0.55         0.56
Mg                              0.56        0.63          0.64         0.62
Na                              0.026       0.029         0.030        0.032
Fe                              0.017       0.026         0.036        0.030
                                     205

-------
           TABLE A-18.   NUTRIENT UPTAKE BY SORGHUM X  SUDANGRASS
	HITH SINGLE APPLICATIONS - 1972	


Rate  	mm/week	50	100   	1_50	200

                                              1st Harvest

N                              66          82           110          108
P                              19          19            20           20
K                              48          49            54           53
Ca             kg/ha           28          26            37           34
Mg                             25          35            39           31
Na                              0.8         0.8            1.3           1.9
Fe                              0.7         1.9            3.4           0.8

                                              2nd Harvest

N                             104         149           103          112
P                              24          26            18           21
K                              42          63            56           66
Ca             kg/ha           32          38            31            31
Mg                             32          49            43           49
Na                              1.7         2.7            2.0           2.4
Fe                              1.0         1.8            1.8           2.6

                                              3rd Harvest

N                              21           75            95           97
P                               6          15            18           17
K                              12          41             50           48
Ca             kg/ha            9          24            29           26
Mg                              7          22            30           31
Na                              0.4         1.5            1.9           1.6
Fe                              0.2         0.8            1.2           2.1
                                    206

-------
TABLE A-19-   NUTRIENT RECOVERY BY SORGHUM X  SUDANGRASS
             WITH SINGLE APPLICATIONS - 1972

Rate

N
P
K
Ca
Mg
Na
Fe

N
P
K
Ca
Mg
Na
Fe
mm/week 50

191
49
102
69
64
2.9
1.9

450
155
62
410
120
492
6
100
Harvested
306
60
153
88
106
5.0
4.5
Applied,
900
310
125
820
240
985
12
150
, kg/ha
308
56
160
97
112
5.2
6.4
kg/ha
1350
465
187
1230
360
1477
18
200

317
58
167
91
111
5.9
5.5

1800
620
250
1640
480
1970
24
Recovered , %
N
P
K
Ca
Mg
Na
Fe
42
31
130
17
53
0.6
30
34
19
99
11
44
0.5
36
23
12
69
8
31
0.4
34
17
9
54
6
23
0.3
22
                           207

-------
(Table A-17).  Nutrient uptake for all  elements increased with irrigation
rate for all harvests (Table A-18).  While total  nutrient uptake for the
season increased with irrigation rate (Table A-19), efficiency of recovery
decreased for all elements.  The trend  is illustrated in Figure A-5.

Sorghum x Sudangrass - Split Applications

     Green and dry yields increased with irrigation rate for all three
harvests (Table A-20).  Dry matter content remained essentially constant.
          TABLE A-20.  YIELD AND DRY MATTER OF SORGHUM X SUDANGRASS
                       WITH SPLIT APPLICATIONS -  1972

Rate
mm/week
50 100 150
200
1st Harvest
    Green Weight, mtons/ha      21.6       36.5
    Dry Matter, %               16.4       16.4
    Dry Weight, mtons/ha         3.53       5.96
42.6
14.9
 6.34
                                              2nd Harvest
    Green Weight, mtons/ha      17.2       25.3
    Dry Matter, %               18.6       18.0
    Dry Weight, mtons/ha         3.20       4.55
34.
16,
 5.58
                                              3rd Harvest
    Green Weight, mtons/ha       5.7       14.5
    Dry Matter, %               20.5       23.0
    Dry Weight, mtons/ha         1.16       3.34
34.3
21.5
 7.37
45.7
14.0
 6.41
42.8
16.0
 6.85
36.5
20.0
 7.30
                                                  Net
Green Weight, mtons/ha
Dry
Dry
Matter,
Weight,
01
h
mtons/ha
44.
17.
7.
5
8
9
76.4
1
1
8.1
3.8
11
1
1
1
7
9
.3
.3
.3
125
16
20
.0
.5
.6

Nutrient content values (Table A-21)  were similar to those obtained for single
applications.  Nutrient uptake increased with irrigation rate (Table A-22)  for
all elements.  Efficiency of recovery decreased with application rate (Table
A-23), and showed similar values for  split and single applications.  Recover-
ies were relatively low due to the high level of N application (Fig. A-6).
                                     208

-------
TABLE A-21.   NUTRIENT COMPOSITION OF SORGHUM X SUDANGRASS
             WITH SPLIT APPLICATIONS - 1972

Rate mm/week

N
P
K
Ca %
Mg
Na
Fe

N
P
K
Ca %
Mg
Na
Fe

N
P
K
Ca %
Mg
Na
Fe

N
P
K
Ca
Mg
Na
Fe
50

1.47
0.47
1.15
0.52
0.74
0.030
0.024

1.65
0.57
0.95
0.82
0.74
0.032
0.021

1.64
0.39
1.22
0.71
0.79
0.062
0.022

1.56
0.50
1.08
0.65
0.74
0.035
0.023
100
1st
1.93
0.36
0.98
0.54
0.74
0.040
0.018
2nd
1.92
0.50
0.88
0.66
0.75
0.035
0.033
3rd
1.85
0.43
1.08
0.74
0.74
0.050
0.072

1.91
0.42
0.97
0.63
0.74
0.040
0.036
150
Harvest
1.89
0.45
1.11
0.58
0.84
0.060
0.019
Harvest
2.25
0.34
0.91
0.54
0.64
0.045
0.018
Harvest
1.44
0.29
0.79
0.61
0.42
0.040
0.013
Net
1.82
0.35
0.93
0.58
0.63
0.048
0.017
200

1.70
0.38
1.20
0.52
0.69
0.058
0.017

2.27
0.42
0.96
0.88
0.74
0.035
0.028

1.63
0.29
0.95
0.64
0.49
0.045
0.013

1.86
0.36
1.04
0.69
0.63
0.045
0.019
                            209

-------
           TABLE A-22.   NUTRIENT  UPTAKE  BY  SORGHUM  X  SUDANGRASS
	WITH  SPLIT  APPLICATIONS  - 1972	


Rate	mm/week	50	100	1_50	200

                                              1st Harvest

N                              52        115            120           109
P                              17          21            28            25
K                              40          58            71            77
Ca             kg/ha            18          32            37            34
Mg                             26          44            54            44
Na                             1.1          2.4           3.8          3.7
Fe                             0.9          1.1           1.2          1.1

                                              2nd Harvest

N                              53          87            125           156
P                              18          22            19            29
K                              30          40            50            66
Ca             kg/ha            26          30            30            60
Mg                             24          34            36            50
Na                             1.0          1.6           2.5          2.4
Fe                             0.7          1.5           1.0          1.9

                                              3rd Harvest

N                              19          62            106           119
P                              4          15            21            21
K                              15          36            58            69
Ca             kg/ha            8          25            45            47
Mg                             9          25            31            36
Na                             0.7          1.7           2.9          3.2
Fe                             0.2          2.4           1.0          0.9
                                    210

-------
TABLE A-23 .  NUTRIENT RECOVERY BY SORGHUM X SUDANGRASS
             WITH SPLIT APPLICATIONS - 1972

Rate

N
P
K
Ca
Mg
Na
Fe

N
P
K
Ca
Mg
Na
Fe
mm/week 50

124
39
85
52
59
2.8
1.8

450
155
62
410
120
492
6
100
Harvested
264
58
134
87
103
5.7
5.0
Applied,
900
310
125
820
240
985
12
150
, kg/ha
351
68
179
112
121
9.2
3.2
kg/ha
1350
465
187
1230
360
1477
18
200

384
75
212
141
130
9.3
3.9

1800
620
250
1640
480
1970
24
Recovered, %
N
P
K
Ca
Mg
Na
Fe
27
25
110
13
48
0.6
29
29
19
87
11
42
0.6
39
26
13
77
9
33
0.6
17
21
12
69
9
27
0.5
16
                           211

-------
                      IRRIGfiTION RfiTE,  MH/NEEK
rv>
                 0
     eoo       1200      seoo
N  APPLIED,  KG/Hfl
                                                                  *
                                                                 Oi
                                                                 UJ!
                                                                 cc
                                                                 UJ!

                    Figure A-6.  Nitrogen recovery by sorghum x sudangrass
                              with split applications - 1972.

-------
Kenaf - Single Applications

     Only one harvest of kenaf was obtained in 1972; the crop simply failed
to regenerate adequately following the first cutting.   Both green and dry
yields increased with irrigation rate (Table A-24), while dry matter content
 TABLE A-24.  YIELD AND COMPOSITION OF KENAF WITH SINGLE APPLICATIONS .- 1972


  Rate	mm/week           50         100         150         200
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
N
P
K
Ca %
Mg
Na
Fe
35.4
17.6
6.23
1.38
0.43
0.92
1.14
0.78
0.11
0.140
41.0
16.4
6.72
1.57
0.36
0.39
1.01
0.78
0.13
0.099
40.3
16.8
6.76
1.69
0.40
1.05
1.07
0.80
0.16
0.099
49.7
17.2
8.56
1.99
0.30
0.98
1.06
0.74
0,15
0.040

 remained essentially constant.   Nitrogen content showed a  slight increase
 with application rate.   Crop uptake of N increased with irrigation  rate,
 while uptake decreased  for Fe and remained essentially unchanged for  the
 other elements.  Nitrogen recovery (Figure A-7)  was low due  to  the  single
 harvest obtained.   Recovery was considerably higher in 1971  when two  cuttings
 were obtained.   Recovery of K was 140% at an irrigation rate of 50  mm/week,
 which indicated that the effluent was deficient  in K at this rate.  Results
 from 1971 (Table A-9) showed this same effect.   Iron was also slightly
 deficient at 50 mm/week, but was adequate at higher rates.   Crop uptake of
 N increased with irrigation rate (Table A-25), while N recovery showed  a
 decrease (Figure A-7).
                                     213

-------
  TABLE A-25.  NUTRIENT RECOVERY BY KENAF WITH SINGLE APPLICATIONS - 1972


Rate	mm/week	50	100	150	200

                                           Harvested, kg/ha

N                             86           105          114          170
P                             27            25           27           20
K                             57            26           71           66
Ca                            71            68           72           72
Mg                            48            53           54           49
Na                             6.8           8.7         10.8         10.1
Fe                             8.7           6.6          6.6          2.7

                                              Applied,  kg/ha

N                            235           470          705          940
P                             85           170          255          340
K                             40            80          120          160
Ca                           212           425          637          850
Mg                            62           125          187          250
Na                           205           510          715         1020
Fe                             3.2           6.5          9.7         13.0

                                              Recovered,  %

N                             37            22           16           18
P                             32            15           11             6
K                            140            32           58           41
Ca                            33            16           11             8
Mg                            77            42           29           20
Na                             2.7           1.7          1.4          1.0
Fe                           270           100           68           21
                                    214

-------
ro
en
                  0
                       IRRIGflTION  RflTE*  MM/MEEK
                            50        100
                    Figure A-7.  Nitrogen recovery by kenaf with single
                              applications - 1972.

-------
Kenaf - Split Applications

     Green and dry yields showed  erratic  trends  with  irrigation  rate  (Table
A-26).   Dry matter content  showed a  decrease,  while N content  showed  an
increase.   Nutrient uptake  values were  somewhat  erratic  (Table A-27),  but  N
showed a slight increase with  irrigation  rate.   Efficiency  of  recovery
decreased  for all  elements  (Figure A-8).   Values of N recovery were similar
for split  and single applications.
 TABLE A-26.   YIELD  AND  COMPOSITION  OF  KENAF WITH  SPLIT APPLICATIONS  -  1972
  Rate
mm/week
50
100
150
200
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
N
P
K
Ca %
Mg
Na
Fe
41 .0
17.8
7.30
1.19
0.40
0.78
1.18
0.71
0.15
0.080
39.4
16.7
6.59
1.63
0.36
0.80
1.19
0.65
0.20
0.082
32.3
16.0
5.17
1.73
0.37
0.78
1.15
0.72
0.26
0.080
44.1
15.6
6.90
1.78
0.31
0.92
1.17
0.59
0.27
0.110
                                    216

-------
TABLE A-27 .   NUTRIENT RECOVERY BY KENAF WITH  SPLIT APPLICATIONS  -  1972

Rate

N
P
K
Ca
Mg
Na
Fe

N
P
K
Ca
Mg
Na
Fe
mm/week 50

87
29
57
86
52
11
5.8

235
85
40
212
62
255
3.2
100
Harvested,
108
24
53
78
43
13
5.4
Applied,
470
170
80
425
125
510
6.5
150
kg/ha
90
19
40
59
37
13
4.1
kg/ha
705
255
120
637
187
765
9.7
200

123
21
64
81
40
19
7.6

940
340
160
850
250
1020
13.0
Recovered, %
N
P
K
Ca
Mg
Na
Fe
37
35
140
40
82
4.3
180
23
14
65
18
34
2.6
83
13
8
33
9
20
1.7
43
13
6
40
10
16
1.8
59
                                   217

-------
ro

oo
   oO
   o
              cc
              I  O
              o
               *

              O
              to
GC
o:
                O-L
                        IRRIGATION  RfiTE,  NH/WEEK
                                               •
                         s HfiRVESTED
                       +—s-
                           200       HOD

                               N  fiPPLl
                                600
800
                                                              200
              UJ
              sr
           ,© SiJ
            fw >
              o
              o
           •  UJ
              or
  -o
1000
                      Figure A-8.  Nitrogen recovery by kenaf with split
                                applications -  1972.

-------
Corn Grain - Single Applications

     Yields of grain were adjusted to a standard dry matter content of 15.5%,
Yields showed a strong response to irrigation rate (Table A-28).   Nitrogen
content also increased, while other elements remained essentially constant.
Nutrient uptake of all elements increased with irrigation rate (Table  A-29),
while efficiency of uptake decreased for all elements, including  N (Figure
A-9).
              TABLE A-28.   YIELD AND COMPOSITION OF CORN GRAIN
                           WITH SINGLE APPLICATIONS -  1972

Rate mm/week
Yield nitons/ha
N
P
K
c/s ^
Mg
Na
50
5.98
1.34
-
0.25
0.42
-
0.15
100
8.78
1.40
-
0.22
0.50
-
0.25
150
9.72
1.42
-
0.23
0.52
-
0.20
200
10.66
1.62
-
0.20
0.51
-
0.22
                                     219

-------
TABLE A-29.   NUTRIENT RECOVERY BY CORN GRAIN
             WITH SINGLE APPLICATIONS - 1972

Rate

N
P
K
Ca
Mg
Na

N
P
K
Ca
Mg
Na
rrm/week 50

80
-
15
25
-
9

290
102
49
262
78
312
100
Harvested
123
-
19
44
-
22
Applied,
580
204
98
524
157
625
150
, kg/ha
138
-
22
50
-
19
kg/ha
870
306
147
786
235
937
200

173
-
21
54
-
23

1160
408
196
1048
314
1250
Recovered, %
N
P
K
Ca
Mg
Na
28
-
31
9.5
-
2.9
21
-
19
8.4
-
3.5
16
_
15
6.4
-
2.0
15
_
11
5.2
_
1.8
                     220

-------
            o
IRRIGflTIGN  RflTE,  HH/WEEK

               IOC?	      ISO
rv>
ro
                         Figure A-9.  Nitrogen recovery by corn grain

                                   with single application - 1972.

-------
Corn Grain - Split Applications

     Yields of grain showed a  strong increase with  irrigation rate (Table
A-30) and were similar to those from single applications.   Nitrogen content
also increased, while other elements showed a decrease.   Uptake of N increased
with irrigation rate (Table A-31),  and  showed similar values  to single appli-
cations.  Recovery efficiency  of N  (Figure A-10)  showed  a  general  decline
with application rate.
               TABLE  A-30.   YIELD AND  COMPOSITION  OF  CORN  GRAIN
                            WITH SPLIT APPLICATIONS -  1972

Rate
Yield
N
P
K
Ca
Mg
Na
mm/week 50
mtons/ha 4.52
1.26
_
0.25
% 0 . 74
-
0.35
100
8.72
1.42
_
0.25
0.58
-
0.25
150
10.66
1.48
_
0.25
0.50
-
0.20
200
10.04
1.75
_
0.25
0.43
-
0.15
                                    222

-------
TABLE A-31.  NUTRIENT RECOVERY BY CORN GRAIN
             WITH SPLIT APPLICATIONS - 1972

Rate

N
P
K
Ca
Mg
Na

N
P
K
Ca
Mg
Na

N
P
K
Ca
Mg
Na
mm/week 50

57
-
11
33
-
16

290
102
49
262
78
312

20
-
22
13
-
5.1
100
Harvested,
124
-
22
50
-
22
Appl led,
580
204
98
524
157
625
Recovered
21
-
22
9.5
-
3.5
150
kg/ha
158
_
27
53
-
21
kg/ha
870
306
147
786
235
937
, %
18
-
18
6.7
-
2.2
200

176
_
25
43
-
15

1160
408
196
1048
314
1250

15
-
13
4.1
-
1.2
                     223

-------
                       IRRIGfiTI
                         5.0
         RflTE,   MH/NEEK
         100          ISO
ro
ro

                     200
i|00      $00
N  flPPLIED,  KG/Hfl
                        Figure A-10.  Nitrogen recovery by corn grain
                                  with split applications - 1972.

-------
Corn SHage - Single Applications

     Corn was harvested for silage when the grain reached  the  hard  dent
stage, 13 weeks after planting.   Green and dry yields  increased  with  irriga-
tion rate (Table A-32), while dry matter content remained  essentially con-
stant.  Content of N also showed an increasing trend.   Uptake  of N  increased
with application rate (Table A-33), while recovery efficiency  decreased
(Figure A-ll).
              TABLE A-32.   YIELD AND COMPOSITION  OF  CORN  SILAGE
                           WITH SINGLE  APPLICATIONS  -  1972

Rate mm/week
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
N
P
K
Ca %
Mg
Na
Fe
50
33.2
18.9
6.27
1.51
0.44
0.90
0.41
0.49
0.040
0.025
100
39.2
17.2
6.74
1.74
0.42
0.95
0.34
0.54
0.045
0.045
150
45.0
18.4
8.29
1.81
0.38
0.68
0.42
0.55
0.110
0.070
200
50.8
18.4
9.36
1.63
0.37
0.80
0,26
0.50
0.038
0.030
                                     225

-------
               TABLE A-33.  NUTRIENT RECOVERY BY CORN SILAGE
                            WITH SINGLE APPLICATIONS - 1972

Rate

N
P
K
Ca
Mg
Na
Fe
mm/week 50

95
28
56
26
30
2.5
1.6
100
Harvested,
118
29
64
22
36
3.0
3.0
150
kg/ha
150
31
56
35
46
9.1
5.7
200

152
35
75
25
47
3.6
2.8
                                             Applied, kg/ha

N                            200           400          600          800
P                             70           140          210          280
K                             31            62           93          134
Ca                           174           358          532          716
Mg                            54           108          162          216
Na                           215           430          645          860
Fe                             3             6            9           12

                                            Recovered,  kg/ha

N                             48            29           25           19
P                             40            21           15           12
K                            170            95           56           56
Ca                            14.4           6.2          6.5          3.
Mg                            56            33           28           22
Na                             1.1           0.7          1.4          0.
Fe                            53            50           63           23
                                   226

-------
o
Q
to
UJ
        Figure A-ll.
Nitrogen recovery by corn silage
with single applications - 1972.

-------
Corn Silage - Split Applications

     Green and dry yields  increased  with  irrigation  rate  (Table  A-34),  while
dry matter content showed  a  slight decrease.   Content  of  N  also  increased.
Nitrogen uptake increased  with  application  rate  (Table A-35), while  efficiency
of recovery generally decreased (Figure A-12).   Recoveries  were  similar for
split and single applications.  This indicated no  advantage to the more fre-
quent irrigations.
              TABLE  A-34.   YIELD AND COMPOSITION OF CORN SILAGE
                           WITH SPLIT APPLICATIONS -  1972

Rate mm/week
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
N
P
K
Ca %
Mg
Na
Fe
50
20.2
19.0
3.83
1.10
0.46
0.92
0.36
0.56
0.045
0.027
100
39.6
18.0
7.15
1.65
0.44
0.95
0.34
0.43
0.062
0.035
150
44.8
17.4
7.80
1.64
0.45
0.88
0.31
0.49
0.065
0.021
200
45.7
16.8
7.66
1.63
0.44
0.90
0.29
0.45
0.078
0.018
                                   228

-------
               TABLE A-35.   NUTRIENT RECOVERY BY CORN SILAGE
                            WITH SPLIT APPLICATIONS - 1972

Rate

N
P
K
Ca
Mg
Na
Fe
mm/ week 50

43
18
35
13
21
1.7
1.0
100
Harvested,
118
32
68
25
30
4.5
2.6
150
kg/ha
128
35
68
25
38
5.0
1.7
200

124
34
69
22
35
5.9
1.3
                                             Applied,  kg/ha

N                            200           400          600          800
P                             70           140          210          280
K                             31            62           93          134
Ca                           174           358          532          716
Mg                            54           108          162          216
Na                           215           430          645          860
Fe                             3             6            9           12

                                             Recovered,  %

N                             21            29           21            16
P                             26            23           17           12
K                            100           100           68           52
Ca                             7.5           6.9           4.6           3.1
Mg                            40            28           24           16
Na                             0.78          1.00         0.78         0.69
Fe                            37            46           20           12
                                    229

-------
fNJ
CO
O
                        IRRIGATION  RftTE,  HH/WEEK
                    o
aOO      400      600
N  HPPLIEO,   KG/Hfi
                                                       8C?0
                       Figure A-12.  Nitrogen recovery by corn silage
                                 with split applications - 1972.

-------
Pearl Millet

     Plots were harvested two times during the season.   Green and dry yields
were somewhat erratic (Table A-36) but tended to remain constant with irriga-
tion rate.  Dry matter content showed a decreasing trend.   Nitrogen content
increased with irrigation rate (Table A-37).   Uptake of N  by the crop showed
an increase with application rate (Table A-38), while efficiency of recovery
decreased (Table A-39 and Figure A-13).  Results from this experiment have
been reported elsewhere (Overman, 1975).
          TABLE A-36.   YIELD AND DRY MATTER OF PEARL  MILLET  -  1972
    Rate
mm/week
50
100
150
200
    Green Weight,  mtons/ha      24.2
    Dry Matter,  %                15.9
    Dry Weight,  mtons/ha         3,85
    Green Weight,  mtons/ha      72.8
    Dry Matter,  %                19.5
    Dry Weight,  mtons/ha        14.2
    Green Weight,  mtons/ha       97
    Dry Matter,  %                18.6
    Dry Weight,  mtons/ha         18.1
                                               1st  Harvest
                          46.8
                          14.1
                           6.61
                        47.5
                        12.5
                         5.94
                                               2nd  Harvest
                          80.2
                          17.5
                          14,0
                         127
                          16.3
                          20.6
                        64.1
                        17.5
                        11.2
                                                   Net
                       112
                        15.4
                        17.1
                         66.8
                         12,8
                          8.53
                         71.9
                         16.5
                         11.9
                        139
                         14,7
                         20.4
                                     231

-------
	TABLE A-37.  NUTRIENT COMPOSITION OF PEARL MILLET - 1972	


Rate	mm/week	50	TOO	150	200

                                             1st Harvest

N                              2.2           2.4          2.8          2.9
P                              0.92          1.00         0.88         0.75
K                              1.52          1.35         2.32         1.73
Ca                             0.48          0.52         0.52         0.48
Mg               %             0.43          0.70         0.71         0.76
Na                             0.035         0.050        0.090        0.110
Fe                             0.105         0.046        0.051         0.031
Zn                             0.0055        0.0050       0.0055       0.0048
Cu                             0.0020        0.0015       0.0013       0.0010

                                             2nd Harvest

N                              1.8           2.3          2.7          2.5
P                              0.73          0.70         0.73         0.68
K                              1.15          1.42         1.52         1.71
Ca                             0.39          0.48         0.53         0.60
Mg               %             0.51          0.50         0.53         0.58
Na                             0.030         0.070        0.070        0.085
Fe                             0.044         0.037        0.038        0.038
Zn                             0.0040        0.0040       0.0052       0.0040
Cu                             0.0010        0.0010       0.0008       0.0008

                                                  Net

N                              1.9           2.3          2.7          2.7
P                              0.78          0.80         0.78         0.70
K                              1.23          1.40         1.80         1.71
Ca                             0.41          0.49         0.52         0.55
Mg               %             0.50          0.56         0.59         0.65
Na                             0.031          0.064        0.077        0.096
Fe                             0.057         0.040        0.042        0.035
Zn                             0.0043        0.0043       0.0053       0.0043
Cu                             0.0012        0.0011        0.0009       0.0009
                                     232

-------
            TABLE A-38.  NUTRIENT UPTAKE BY PEARL MILLET - 1972
Rate
mm/week
 50
100
150
200
P
K
Ca
Mg
Na
Fe
Zn
Cu
P
K
Ca
Mg
Na
Fe
Zn
Cu
P
K
Ca
Mg
Na
Fe
Zn
Cu
kg/ha
kg/ha
kg/ha
 85
 35
 59
 18
 17
  1.3
  4.0
  0.21
  0.077
255
104
164
 55
 72
  4.3
  6.3
  0.56
  0.14
340
139
223
 73
 89
  5.6
 10.3
  0.77
  0.22
                                             1st Harvest
159
66
89
34
46
3.4
3.0
0.34
0.100
2nd
323
98
199
67
70
9.9
5.2
0.56
0.14

482
164
288
101
116
13.3
8.2
0.90
0.24
166
52
138
31
42
5.4
3.0
0.32
0.077
Harvest
302
82
170
59
59
7.8
4.3
0.58
0.08
Total
468
134
308
90
101
9.7
7.3
0.90
0.15
                           246
                            64
                           147
                            41
                            65
                             9.5
                             2.7
                             0.40
                             0.085
                           297
                            81
                           203
                            71
                            69
                            10.1
                             4.5
                             0.47
                             0.09
                           543
                           145
                           350
                           112
                           134
                            14.0
                             8.2
                             0.87
                             0.18
                                    233

-------
          TABLE A-39.  NUTRIENT RECOVERY  BY  PEARL  MILLET  -  1972
Rate	mm/week	50	100	150	200

                                          Harvested,  kg/ha

N                            340          482           468           534
P                            139          164           134           145
K                            223          288           308           350
Ca                            73          101             90           112
Mg                            89          116           101           134
Na                             5.6          13.3           9.7         14.0
Fe                            10.3           8.2           7.3          8.2
Zn                             0.77          0.90          0.90         0.87
Cu                             0.22          0.24          0.15         0.18

                                             Applied,  kg/ha

N                            460          920          1380         1840
P                            150          300           450           600
K                             78          156           234           312
Ca                           390          780          1170         1560
Mg                           122          245           367           490
Na                           500         1000          1500         2000
Fe                             5           11             16           22
Zn                             1.8           3.6           5.4          7.2
Cu                             1.1           2.2           3.3          4.4

                                             Recovered,  %

N                             74           52            34           30
P                             93           54            30           24
K                            280          185           130           110
Ca                            19           13            8            7
Mg                            73           47            27           27
Na                             1.1           1.3           0.9          1.0
Fe                           185           73            43           32
Zn                            43           24            17           12
Cu                            20           10            5            4
                                    234

-------
ro
oo
en
              I  O
              X
              o
              Q

              UJ
flC
                 tfs
                        IRRIGflTION  RflTE,  MM/WEEK
                                       1
                                    150    ,    ZOO
                                       Jimnjm	I	umil-.ii»»
                       © s HftBVESTED
   LUi
   oc
,0  UJ
*  >
   o
   o
   UJ
   flC
                      Figure A-13.  Nitrogen recovery by pearl millet - 1972.

-------
1972 WINTER CROPS

     Rye (Wrens Abruzzl)  and ryegrass  (Florida Rust Resistant)  were utilized
as in 1971.  All  plots were prepared by disking,  plowing and disking.   Seeding
rates were 1.7 hl/ha (2 bu/acre)  for rye and 23 kg/ha (20 Ib/acre)  for rye-
grass.  All plots exhibited vigorous growth.

     Effluent characteristics for the  period 10/72-3/73 are shown in Table 6.
Values for K, Ca, Mg and  Na were  approximated as  those from the period 4/72-
9/72.

     Rye was harvested on March 22,  1973,  and ryegrass on March 27.   No plots
were harvested in January due to  unavailability of equipment.   At irrigation
rates of 75 and 100 mm/week, both rye  and  ryegrass showed considerable lodging
due to high wind gusts just prior to harvest.  Much of the vegetation  in these
plots was inaccessible to the forage harvester.

     Forage samples were  analyzed as outlined for 1971.

Rye

     Green and dry yields declined sharply at the upper irrigation  rates due
to lodging.  Dry matter content decreased  with irrigation rate, while  N con-
tent showed an increase (Table A-40).   Nutrient uptake (Table A-41)  also
reflected the problem of  lodging.  However,  uptake values at 25 and  50 mm/week
were accurate due to negligible lodging and  showed the typical  upward  trend.
Recovery efficiencies (Figure A-14)  obtained for  the lower rates were  more
accurate.
              TABLE A-40.   YIELD  AND  COMPOSITION  OF  RYE  -  1972


    Rate	mm/week         25           50           75         100
Green Weight, mtons/ha
Dry
Dry
N
P
K
Ca
Mg
Na
Fe
Al
Matter, %
Weight, mtons/ha



°i
k




15.5
25.5
3.95
1.84
0.76
2.02
0.52
0.31
0.050
0.021
0.010
19.3
23.6
4.55
1.96
0.84
2.21
0.49
0.35
0.060
0.024
0.010
11.6
22.4
2.60
2.34
0.78
2.50
0.56
0.35
0.063
0.025
0.010
7.6
20.9
1.59
2.56
0.88
2.30
0.56
0.44
0.108
0.031
0.015
                                    236

-------
TABLE A-41. NUTRIENT RECOVERY BY RYE -
1972


Rate

N
P
K
Ca
Mg
Na
Fe
Al

N
P
K
Ca
Mg
Na

N
P
K
Ca
Mg
Na
mm/ week 25

73
30
80
21
12
2.0
0.83
0.40

190
64
30
154
46
188

38
47
270
14
26
1.1
50
Harvested,
89
38
101
22
16
2.7
1.09
0.46
Applied,
380
128
60
308
92
376
Recovered
23
30
170
7
17
0.7
75
kg/ha
61
20
65
15
9
1.6
0.65
0.26
kg/ha
570
192
90
462
138
564
, kg/ha
11
10
72
3
7
0.3
100

41
14
37
9
7
1.7
0.49
0.24

760
256
120
616
184
752

5
6
31
1
4
0.2
237

-------
ro
CjO
CD
                        IRRIGflTION RflTE,   MM/WEEK
                 o
                 o-
              X
              v,
              O
               e,

              O

              UJ o.
:LiJ
>
ir
CE
                 tf*__
                 <%J
25
5.0
                             75
                      © E HflRVESTED
                  0
            200
400
                  600
@00
                              N  fiPPLlEO,  KG/Hfl
                                                            1£S
                                                  o
                                                 "*& X'
                                                               4-  o
                                                                  LU!
                                                                  o
iODD
                        Figure A-14.  Nitrogen recovery by rye - 1972.

-------
Ryegrass

     Lodging was also a problem for ryegrass at the higher irrigation  rates,
as shown by the green and dry yields (Table A-42).   At irrigation rates  of
25 and 50 mm/week, N uptake showed an increase (Table A-43),  as  expected.
Recovery efficiency for N declined (Figure A-15)  with application rate.
            TABLE A-42.   YIELD AND COMPOSITION OF RYEGRASS  -  1972
    Rate
mm/week
25
50
75
100
Green Weight, mtons/ha
Dry
Dry
N
P
K
Ca
Mg
Na
Fe
Al
Matter, %
Weight, mtons/ha



%




30.4
15.5
4.71
1.93
0.54
1.73
0.56
0.39
0.25
0.032
0.010
32.3
21.9
7.07
2.03
0.60
1.74
0.65
0.40
0.51
0.038
0.010
27.8
14.7
4.09
2.07
0.68
1.70
0.69
0.52
0.84
0.047
0.010
24.2
14.4
3.48
2.67
0.69
1.70
0.59
0.45
1.18
0.041
0.020
                                    239

-------
TABLE A-43.  NUTRIENT RECOVERY BY RYEGRASS -  1972

Rate

N
P
K
Ca
Mg
Na
Fe
AT

N
P
K
Ca
Mg
Na
mm/week 25

91
25
81
26
18
12
1.5
0.47

190
64
30
154
46
188
50
Harvested
144
42
123
46
28
36
2.7
0.71
Applied,
380
128
60
308
92
376
75
, kg/ha
85
28
70
28
21
34
1.9
0.41
kg/ha
570
192
90
462
138
564
100

93
24
59
21
16
41
1.4
0.70

760
256
120
616
184
752
Recovered, %
N
P
K
Ca
Mg
Na
48
39
270
17
39
6.4
38
33
200
15
30
9.6
15
15
78
6
15
6.0
12
9
49
3
9
5.5
                       240

-------
      IRRIGRTION
0        25       50
cc
X
Q
yj
t—
to
x a-
75
          CD s HRRVESTED
                                                   125
                                                       .o
                                                          LU
                                                       •O
          Figure A-15.  Nitrogen recovery by ryegrass  - 1972,

-------
1973 SUMMER CROPS

     Crops Included sorghum x sudangrass (Asgrow Gazer-A), kenaf (Everglades
41), pearl millet (Asgrow Star), and corn (Pioneer 3369 A) for silage and for
grain.  All plots were disked, plowed and disked again.  Planting and har-
vesting followed the schedule of Table A-44.  Sorghum x sudangrass plots were
                 TABLE A-44.   FIELD SCHEDULE FOR SUMMER 1973

Crop
Sorghum x sudangrass
Kenaf
Corn Silage
Corn Grain
Pearl Millet
Planting
4/11/73
4/11/73
4/25/73
4/25/73
4/25/73
Cultivation Harvesting
6/22/73 6/21/73
8/30/73 8/29/73
10/24/73
7/11/73 7/10/73
7/10/73
8/30/73
6/21/73
8/29/73

rotovated on June 21, 1973, following the first harvest to control  crabgrass.
Corn was planted in 90 cm (36 in.)  and 45 cm (18 in.)  rows at seeding rates
of 17 kg/ha and 34 kg/ha, respectively.   Pearl  millet  was  drilled (broadcast
planted) at 28 kg/ha.  Sorghum x sudangrass and kenaf  were both planted in
90 cm rows at 11 kg/ha.

     Characteristics of the effluent for the period 4/73-9/73 are given in
Table 6.

Sorghum x Sudangrass

     Three harvests were obtained.   Green and dry yields increased  with
irrigation rate (Table A-45), while dry matter content remained essentially
constant.  Nitrogen composition was independent of rate (Table A-46).  Crop
uptake of various elements increased with irrigation rate  (Table A-47), while
efficiency of recovery showed a decreasing trend (Table A-48 and Figure A-16),
                                     242

-------
TABLE A-45. YIELD AND DRY MATTER OF SORGHUM X SUDANGRASS
- 1973

Rate mm/ week

Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
100

37.2
17.0
6.32
150
1st Harvest
39.6
16.3
6.47
200

70.6
16.5
11.65
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
23.1
23.0
 5.31
10.8
20.3
 2.20
71.1
19.5
13.8
2nd Harvest

     26.2
     24.2
      6.34

3rd Harvest

     11.2
     20.1
      2.26

     Net

     77.0
     19.6
     15.1
 26.2
 23.4
  6.14
 12.3
 21.5
  2.64
109.1
 18.8
 20.4
                                     243

-------
TABLE A-46. NUTRIENT
COMPOSITION OF SORGHUM X
SUDANGRASS -
1973

Rate mm/ week

N
P
K
Ca
Mg %
Na
Fe
Zn
Mn

N
P
K
Ca
Mg %
Na
Fe
Zn
Mn

N
P
K
Ca
Mg %
Na
Fe
Zn
Mn

N
P
K
Ca
Mg %
Na
Fe
Zn
Mn
100
1st
1.44
0.40
0.79
0.46
0.48
0.100
0.0085
0.0047
0.00085
2nd
1.13
0.25
0.28
0.38
0.31
0.220
0.0125
0.0063
0.00035
3rd
1.66
0.30
0.37
0.63
0.47
0.240
0.0402
0.0022
0.00050

1.35
0.33
0.53
0.46
0.41
0.17
0.015
0.0049
0.00060
150
Harvest
1.35
0.30
0.75
0.45
0.43
0.130
0.0132
0.0034
0.00050
Harvest
1.09
0.22
0.36
0.40
0.28
0.180
0.0095
0.0046
0.00075
Harvest
1.73
0.26
0.34
0.65
0.43
0.245
0.0322
0.0071
0.00075
Net
1.30
0.26
0.53
0.49
0.37
0.17
0.014
0.0044
0.00064
200

1.40
0.30
0.82
0.43
0.42
0.120
0.0135
0.0040
0.00075

1.18
0.23
0.39
0.35
0.25
0.225
0.0635
0.0175
0.00100

1.78
0.28
0.31
0.69
0.44
0.185
0.0585
0.0043
0.00100

1.38
0.28
0.62
0.44
0.37
0.16
0.034
0.0081
0.00086
244

-------
TABLE A-47.   NUTRIENT  UPTAKE  BY  SORGHUM  X SUDANGRASS  -  1973

Rate mm/week

N
P
K
Ca
Mg kg/ha
Na
Fe
Zn
Mn

N
P
K
Ca
Mg kg/ha
Na
Fe
Zn
Mn

N
P
K
Ca
Mg kg/ha
Na
Fe
Zn
Mn
100

91
25
50
29
30
6.3
0.54
0.30
0.054

60
13
15
20
16
11.6
0.66
0.34
0.019

36
7
8
14
10
5.3
0.88
0.048
0.011
150
1st Harvest
87
19
49
29
28
8.4
0.85
0.22
0.032
2nd Harvest
69
14
23
25
18
11.4
0.60
0.29
0.048
3rd Harvest
39
6
8
19
10
5.5
0.73
0.160
0.017
200

163
35
96
50
49
14.0
1.57
0.47
0.087

72
14
24
22
15
13.8
3.90
1.08
0.061

47
7
8
18
12
4.9
1.55
0.114
0.026
                            245

-------
	TABLE  A-4d  NUTRIENT RECOVERY BY SORGHUM X SUDANGRASS - 1973


Rate	mm/week	100	150	200

                                             Harvested, kg/ha

N                                     187           195          282
P                                      45            39           56
K                                      73            80          128
Ca                                     63            73           90
Mg                                     56            56           76
Na                                     23            25           33
Fe                                      2.1            2.2          7.0
Zn                                      0.69          0.67         1.66

                                              Applied, kg/ha

N                                     670          1000         1340
P                                     245           370          490
K                                     195           290          390
Ca                                   1680          2520         3360
Mg                                    465           700          930
Na                                   1455          2180         2910
Fe                                     29            44           58
Zn                                      8.7           13.1          17.4

                                               Recovered,  %

N                                      28            20           21
P                                      18            11           11
K                                      37            28           33
Ca                                      3.7            2.9           2.7
Mg                                     12.0            8.0           8.2
Na                                      1.6            1.2           1.1
Fe                                      7.1            5.0          12.0
Zn                                      7.9            5.1           9.6
                                    246

-------
Figure A-16.   Nitrogen recovery by  sorghum
              x sudangrass  -  1973,

-------
Kenaf

     As in 1972, the kenaf failed to  regenerate after first harvest.   Green
and dry yields showed the characteristic  increase  with irrigation  rate (Table
A-49), while dry matter content  decreased slightly.   Nutrient  composition was
slightly erratic.   Nitrogen uptake was  essentially constant (Table A-50),
while N recovery decreased rapidly with irrigation rate (Figure  A-17).
             TABLE A-49.   YIELD  AND  COMPOSITION  OF  KENAF  -  1973
    Rate
mm/week
100
150
200
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
N
P
K
Ca %
Mg
Na
Fe
Zn
Mn
24.6
18.7
4.61
1.86
0.47
0.71
0.99
0.48
0.142
0.0105
0.0065
0.0015
26.4
17.9
4.73
1.86
0.35
0.65
0.96
0.51
0.114
0.0045
0.0068
0.00085
27.6
17.6
4.84
1.67
0.33
0.77
0.87
0.43
0.109
0.0055
0.0056
0.00085
                                    248

-------
              TABLE A-50.  NUTRIENT RECOVERY BY KENAF - 1973
Rate	mm/week	IjOO	150	200

                                             Harvested, kg/ha

N                                      86            88           81
P                                      22            17           16
K                                      33            31           37
Ca                                     46            45           42
Mg                                     22            24           21
Na                                     66            54           53
Fe                                      4.8           2.1          2.7
Zn                                      3.0           3.2          2.7
Mn

                                              Applied, kg/ha

N                                     280           420          560
P                                     106           159          212
K                                      64            96          168
Ca                                    710          1070         1420
Mg                                    196           294          392
Na                                    620           930         1240
Fe                                     12            18           24
Zn                                      3.68          5.52         7.36
Mn                                     -

                                               Recovered, %

N                                      31            21           14
P                                      21            10            8
K                                      51            32           22
Ca                                      6.4           4.2          3.0
Mg                                     11.2           8.2          5.3
Na                                     10.6           5.8          4.2
Fe                                     40            12           11
Zn                                     82            58           37
                                     249

-------
en
O
                      IRRIGATION  RfiTE,  HM/I^EEK
   o
   Ifjf
p
                 CC
                 O
                    0
                    o-
                 to
oc
I
                    o-
                     o
                           50    100
                            200   250
                                            O s
                              ;5TED =
            200      100

            N  flPPLIED,
                          600
                                                          °
                                                          &
                                                            >?
                                         ,0 Q

                                           yj
                                           O
                                                          o
                                                          
-------
Pearl Millet

     Two cuttings were obtained.  The first harvest was at 8 weeks  of age.
Some vegetation could not be harvested from the 200 mm/week plot due to
lodging; the crop should have been harvested at 6 or 7 weeks after  planting.
Green and dry yields showed an upward trend with irrigation rate (Table A-51
while dry matter content showed a downward trend.  Nitrogen content also
tended upward (Table A-52).  Crop uptake of N showed a slight increase of N
with application rate (Table A-53).   Efficiency of N recovery decreased in
the typical manner (Table A-54, Figure A-18).
      TABLE A-51.  YIELD AND DRY MATTER OF PEARL MILLET (GAHI-1)  -  1973
    Rate
mm/week
50
100
150
200
                                               1st Harvest
    Green Weight, mtons/ha      45.2        46.1
    Dry Matter, %               14.3        12.6
    Dry Weight, mtons/ha         6.47        5.82
                                       53.8
                                       12.1
                                        6.50
                                               2nd Harvest
    Green Weight, mtons/ha      19.3        23.5
    Dry Matter, %               25.1        25.7
    Dry Weight, mtons/ha         4.84        6.03
    Green Weight, mtons/ha      64.5        69.6
    Dry Matter, %               17.5        17.0
    Dry Weight, mtons/ha        11.3        11.8
                                                   Net
                                       24.0
                                       23.9
                                        5.71
                                       77.8
                                       15.7
                                       12.2
                                    43.9
                                    12.3
                                     5.40
                                    26.9
                                    23.2
                                     6.23
                                    70.8
                                    16.4
                                    11.6
                                    251

-------
     TABLE A-52.  NUTRIENT COMPOSITION OF PEARL MILLET  (GAHI-1)  -  1973
Rate
mm/week
50
TOO
150
200
P
K
Ca
Mg
Na
Fe
Zn
Mn
P
K
Ca
Mg
Na
Fe
Zn
Mn
P
K
Ca
Mg
Na
Fe
Zn
Mn
                                              1st Harvest
1.58
0.81
0.89
0.39
0.63
0.029
0.042
0.027
0.0032
1.62
0.86
1.02
0.43
0.70
0.030
0.028
0.019
0.0031
1.78
0.70
1.00
0.44
0.67
0.031
0.018
0.011
0.0032
1.89
0.60
1.11
0.50
0.70
0.038
0.015
0.008
0.0026
                                              2nd Harvest
1.20
0.75
0.70
0.45
0.53
0.009
0.0115
0.0128
0.0021
1.01
0.67
0.75
0.36
0.54
0.010
0.0045
0.0062
0.0011
1.25
0.63
0.67
0.42
0.60
0.012
0.0058
0.0128
0.0020
1.35
0.54
0.76
0.43
0.63
0.010
0.0042
0.0072
0.0014
                                                    Net
1.42
0.78
0.81
0.41
0.59
0.021
0.029
0.021
0.0027
1.30
0.76
0.88
0.40
0.62
0.020
0.016
0.013
0.0021
1.53
0.67
0.85
0.43
0.64
0.022
0.012
0.012
0.0026
1.61
0.57
0.92
0.46
0.66
0.023
0.009
0.008
0.0020
                                     252

-------
       TABLE  A-53.  NUTRIENT UPTAKE BY PEARL MILLET (GAHI-1) - 1973	


Rate	mm/week	50	HX)	150	200

                                              1st Harvest

N                             102           94          115          103
P                              52           50           45           32
K                              58           60           65           60
Ca                             25           25           29           27
Mg             kg/ha           41           41           44           38
Na                              1.92         1.71         2.02         2.05
Fe                              2.73         1.66         1.15         0.80
Zn                              1.74         1.12         0.72         0.45
Mn                              0.21         0.18         0.21         0.14

                                              2nd Harvest

N                              58           61           71           84
P                              36           40           36           34
K                              34           45           38           47
Ca                             22           22           24           27
Mg             kg/ha           26           33           34           39
Na                              0.44         0.63         0.68         0.65
Fe                              0.56         0.27         0.34         0.26
Zn                              0.62         0.37         0.73         0.45
Mn                              0.10         0.07         0.11         0.09

                                                    Total

N                             160          155          186          187
P                              88           90           81           66
K                              92          105          103          107
Ca                             47           47           53           54
Mg             kg/ha           67           77           78           77
Na                              2.36         2.34         2.70         2.70
Fe                              3.29         1.93         1.49         1.06
Zn                              2.36         1.49         1.45         0.90
Mn                              0.31         0.25         0.32         0.23
                                    253

-------
      TABLE A-54 •   NUTRIENT RECOVERY BY PEARL MILLET (6AHI-1)  -  1973

Rate

N
P
K
Ca
Mg
Na
Fe
Zn
mm/ week 50

160
88
92
47
67
2.36
3.29
2.36
100
Harvested,
155
90
105
47
77
2.34
1.93
1.49
150
kg/ha
186
81
103
53
78
2.70
1.49
1.45
200

187
66
107
54
77
2.70
1.06
0.90
                                            Applied,  kg/ha

N                             175           350           525           700
P                              60           120           180           240
K                              50           100           150           200
Ca                            425           850          1275          1700
Mg                            112           224           336           448
Na                            365           730          1095          1460
Fe                              5            11            16           22
Zn                              1.7           3.4          5.1          6.8

                                               Recovered, %

N                              91            44            35           27
P                             150            75            45           28
K                             180           105            69           54
Ca                             11.1           5.5          4.2          3.2
Mg                             60            34            23           17
Na                              0.65          0.32         0.25         0.18
Fe                             66            18            9            5
Zn                            140            44            28           13
                                   254

-------
cn


 RRIGflTION

	^—
RflTE,  MM/WEEK

        I|G     gqO

                                         O s HfiRVESTED
                               200
                                                            O
                                                            O
                                                            •£ «
                                                               Lu
                                                            tf>
                                                               UJ
                                                            •o
                                       i L, U f
                    Figure A-18.  Nitrogen recovery by pearl millet - 1973,

-------
Corn Silage - 90 cm Rows

     A plant density of approximately 45,000  plants/ha  (18,000 plants/acre)
was used.   Both green and dry yields  increased  with  irrigation rate (Table
A-55), while dry matter content  and N content remained  essentially constant.
Uptake of all elements showed an upward  trend with application rate (Table
A-56).  Recovery efficiency for  N decreased downward (Figures  A-19) from 44%
at 50 mm/week.
              TABLE A-55.   YIELD  AND  COMPOSITION  OF  CORN  SILAGE
   	IN  90  CM RONS  -  1973	


    Rate         mm/week        50          100          150          200
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
N
P
K
Ca %
Mg
Na
Fe
Zn
Mn
23
22.2
5.1
1.22
0.48
0.50
0.22
0.25
0.0160
0.0060
0.0042
0.00120
26
23.5
6.1
1.23
0.37
0.57
0.18
0.23
0.0150
0.0060
0.0045
0.00085
34
24.2
8.2
1.09
0.32
0.52
0.13
0.22
0.0085
0.0023
0.0024
0.00075
35
23.3
8.2
1.14
0.35
0.62
0.18
0.21
0.0170
0.0060
0.0044
0.00085
                                    256

-------
TABLE A-56.   NUTRIENT  RECOVERY  BY CORN SILAGE
             IN  90  CM  ROWS  -  1973

Rate

N
P
K
Ca
Mg
Na
Fe
Zn
Mn

N
P
K
Ca
Mg
Na
Fe
Zn
Mn
mm/week 50

62
24
26
11
13
0.82
0.31
0.21
0.061

140
53
42
355
98
310
6
1.84
-
100
Harvested,
75
23
35
11
14
0.92
0.37
0.27
0.052
Applied,
280
106
84
710
196
620
12
3.68
-
150
kg/ha
89
26
43
11
18
0.70
0.19
0.20
0.062
kg/ha
420
159
126
1060
294
930
18
5.52
-
200

93
29
51
15
17
1.
0.
0.
0.

560
212
168
1420
392
1240
24
7.








39
49
36
070








31

Recovered, %
N
P
K
Ca
Mg
Na
Fe
Zn
Mn
44
45
62
3.1
13
0.26
5.2
11
-
27
22
42
1.5
7.1
0.15
3.1
7.3
-
21
16
34
1.0
6.1
0.08
1 .1
3.6

17
14
30
1.
4.
0.
2.
4.
-



1
3
11
0
9

                     257

-------
CO
     IRRIGfiTIGN

   ©0,      5,0     IOC
      —H———r
                  cc
                  o
to
LU
•>
££
cr
                      0
                                         1 SO    200    250
                                                s HflRVESTED  ..
                                         +    i     I    I
                                                             ,o
                                                               .X*
                                                               LU
                                                               O
                                                               HJ
             aoo       ^oo      eoo

            M  fiPPLIED,  KG/Hfl
                        Figure A-19.  Nitrogen recovery by corn silage
                                   in 90 cm rows - 1973.

-------
Corn Silage - 45 cm Rows

     Double planting was used to achieve a plant density of approximately
90,000 plants/ha (36,000 plants/acre).  Increased irrigation rates caused
higher green and dry yields (Table A-57), with dry matter content and N con-
tent remaining essentially constant.  Crop uptake of all elements increased
with application rate (Table A-58), with efficiency of recovery showing a
decrease for N (Figure A-20).
              TABLE A-57.  YIELD AND COMPOSITION OF CORN SILAGE
                           IN 45 CM ROWS - 1973

Rate mm/week
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
N
P
K
Ca %
Mg
Na
Fe
Zn
Mn
50
20.4
19.0
4.0
1.42
0.56
0.62
0.28
0.30
0.0225
0.0162
0.0051
0.0017
100
30.2
19.5
5.7
1.45
0.43
0.64
0.23
0.26
0.0285
0.0132
0.0044
0.0010
150
39.6
20.8
8.2
1.31
0.40
0.54
0.25
0.29
0.0130
0.0058
0.0050
0.0011
200
46.1
19.2
8.9
1.56
0.40
0.67
0.27
0.27
0.0320
0.0120
0.0086
0.0011
                                     259

-------
TABLE A-5&  NUTRIENT RECOVERY BY CORN SILAGE
            IN 45 CM ROWS - 1973

Rate

N
P
K
Ca
Mg
Na
Fe
Zn
Mn

N
P
K
Ca
Mg
Na
Fe
Zn
Mn
mm/week 50

57
22
25
11
12
0.90
0.65
0.20
0.068

140
53
42
355
98
310
6
1.84
-
100
Harvested,
83
25
36
13
15
1.62
0.75
0.25
0.057
Applied,
280
106
84
710
196
620
12
3.68
-
150
kg/ha
107
33
44
21
24
1.07
0.48
0.41
0.090
kg/ha
420
159
126
1060
294
930
18
5.52
-
200

139
36
60
24
24
2.85
1.07
0.77
0.098

560
212
168
1420
392
1240
24
7.36
-
Recovered, %
N
P
K
Ca
Mg
Na
Fe
Zn
Mn
41
42
60
3.1
12
0.29
11
11
_
30
24
43
1.8
7.7
0.26
6.2
6.8
_
25
21
35
2.0
8.2
0.12
2.7
7.4
_
25
17
36
1.7
6.1
0.23
4.5
10.5
_
                  260

-------
      RRIGflTION  RfiTE,  MM/WEEK
   0Q     SO     100    150    200    2SO
UJ
i—
to
yj
>
oc
4-0 o
    yj
    CC
    yj
                              = oiQBwpejcn
                              ™ n In BI ₯ C 3 I t U
                                           •o
      Figure A-20.  Nitrogen recovery by corn silage
                in 45 cm rows - 1973.

-------
Corn Grain

     Corn was planted in 90 cm rows at a density of 45,000 plants/ha.   Plots
were harvested 18 weeks  after planting.   Green and dry weights showed  a strong
increase with irrigation rate (Table A-59),  while dry matter content remained
essentially constant.  Nitrogen content  also increased with rate.   Calcium
was not determined due to an oversight.   Plant uptake of all  elements
increased with application rate (Table A-60).   Efficiency of recovery  of N
showed a slight upward trend (Figure A-21),  but was very low for all rates,
    TABLE A-59.   YIELD AND COMPOSITION  OF CORN  GRAIN  IN  90  CM RONS  -  1973


    Rate         mm/week        50          100          150         200
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
N
P
K
1.68
85.8
1.43
1.32
0.36
0.38
2.91
81.9
2.37
1.50
0.35
0.37
5.38
84.7
4.55
1.46
0.32
0.34
6.83
84.5
5.78
1.63
0.30
0.31
    Ca             %              -
    Mg                          0.092        0.100        0.108        0.095
    Na                          0.0010       0.0005       0.0005       0.0015
    Fe                          0.0085       0.0101       0.0068       0.0145
    Zn                          0.0028       0.0016       0.0015       0.0014
    Mn                          0.0001       0.0007       0.0001       0.0001
                                    262

-------
TABLE A-60L   NUTRIENT RECOVERY BY CORN GRAIN IN 90 CM ROUS - 1973

Rate

N
P
K
Ca
Mg
Na
Fe
Zn
Mn

N
P
K
Ca
Mg
Na
Fe
Zn
Mn
mm/week 50

19
5.1
5.4
-
1.3
0.014
0.12
0.040
0.001

140
52
32
355
98
300
6
1.8
-
100
Harvested
36
8.3
8.8
-
2.4
0.012
0.24
0.038
0.017
Applied,
280
105
64
710
195
600
12
3.7
-
150
, kg/ha
66
14.6
15.5
_
4.9
0.023
0.31
0.068
0.005
kg/ha
420
157
96
1065
293
900
18
5.5
-
200

94
17.3
17.9
_
5.5
0.087
0.84
0.081
0.006

560
210
168
1420
390
1200
24
7.4
-
Recovered, %
N
P
K
Ca
Mg
Na
Fe
Zn
Mn
14
9.8
17
-
1.3
0.005
2.0
2.2
-
13
7.9
14
-
1.2
0.002
2.0
1.0
-
16
9.3
16
-
1.7
0.003
1.7
1.2
—
17
8.2
11
-
1.4
0.007
3.5
1.1
~
                               263

-------
ro
CT)
                       IRRIGATION  RftTE,  HH/MEEK
                     uv
                  o
UJ
I—
4O
yj

£C
0
           !__1|L_J4L
                              200
                                             © s HiBRVESTED
                               600
                                                           o
                                        UJ

                                        o
                                        o
                                        UJ
                                        !3C
                                                           -O
800
                         Figure A-21.  Nitrogen recovery by corn grain
                                   in 90 cm rows - 1973.

-------
1973 WINTER CROPS

     Rye (Wrens Abruzzi)  and ryegrass (Gulf Annual)  were seeded  at  rates  of
0.9 hl/ha (1 bu/acre)  and 1.3 hl/ha (1.5 bu/acre),  respectively, using a
cultipacker seeder.   Before planting, all  plots were  disked,  plowed  and disked
again.   Both crops grew vigorously and provided three cuttings.  The  schedule
of planting and harvesting as shown Table A-61.

     Effluent characteristics for this period are given  in Table 6.
                 TABLE A-61.   FIELD SCHEDULE FOR WINTER  1973
                     Operation
 Date
                     Planting

                     Harvesting
                        1st
                        2nd
                        3rd
11/7/73
1/17/74
2/13/74
 4/4/74
Rye

     Yields of green and dry forage showed an increase  with  irrigation  rate
(Table A-62), while dry matter content showed a  slight  downward  trend.
Nitrogen content showed a definite increase with irrigation  rate (Table A-63),
while other elements showed much smaller changes.   Crop uptake of N  showed a
strong upward trend (Table A-64).   Nitrogen recovery  (Table  A-65,  Figure A-22)
followed the characteristic decline with application.   Uptake of K exceeded
supply at 25 and 50 mm/week (Table A-65).   This  could  lead to deficiency under
prolonged practice.
                                     265

-------
              TABLE A-62.   YIELD AND DRY MATTER OF RYE  - 1973
Rate
mm/week
25
50
75
100
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
Green Weight,  mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
Green Weight,  mtons/ha
Dry Matter,  %
Dry Weight,  mtons/ha
Green Weight,  mtons/ha
Dry Matter,  %
Dry Weight,  mtons/ha
                  5.44
                 17.8
                  0.97
                  1.70
                 23.3
                  0.39
                  9.50
                 25.2
                  2.39
                 16.6
                 22.6
                  3.75
               1st Harvest

              8.02         7.20
             13.8         15.8
              1.11         1.15

               2nd Harvest

              2.66         2.87
             20.8         20.0
              0.56         0.57

               3rd Harvest

             13.31        13.10
             22.0         20.4
              2.93         2.67
                                                   Net
             24.0
             19.1
              4.60
             23.3
             18.9
              4.39
                           9.21
                          16.0
                           1.47
                           2.31
                          19.9
                           0.46
                          13.78
                          20.4
                           2.81
             25.3
             18.8
              4.74
                                    266

-------
TABLE A-63.  NUTRIENT CONTENT OF RYE - 1973

Rate mm/week

N
P
K
Ca
Mg %
Na
Fe
Zn
Mn
Cu

N
P
K
Ca
Mg %
Na
Fe
Zn
Mn
Cu

N
P
K
Ca
Mg %
Na
Fe
Zn
Mn
Cu
25

4.13
0.64
2.20
0.47
0.29
0.021
0.040
0.0010
0.0032
0.0012

3.18
0.52
1.46
0.36
0.26
0.041
0.016
0
0.0030
0.0010

1.77
0.37
1.90
0.24
0.20
0.012
0.020
0
0.00125
0.00075
50
1st Harvest
4.42
0.69
1.46
0.48
0.34
0.026
0.027
0.0022
0.0015
0.0013
2nd Harvest
3.61
0.50
1.51
0.39
0.30
0.024
0.017
0
0.0013
0.0012
3rd Harvest
2.67
0.40
1.60
0.33
0.24
0.009
0.016
0
0.00075
0.00075
75

4.06
0.65
1.80
0.57
0.32
0.018
0.098
0.0000
0.0020
0.0018

4.01
0.51
1.55
0.45
0.31
0.028
0.016
0
0.0010
0.0010

2.41
0.44
1.51
0.40
0.25
0.012
0.010
0
0.00025
0.00075
100

4.42
0.65
1.28
0.54
0.32
0.026
0.092
0.0072
0.0020
0.0020

4.18
0.56
1.57
0.46
0.31
0.021
0.015
0
0.0010
0.0010

2.82
0.46
1.49
0.47
0.28
0.009
0.010
0
0.00050
0.00075

                                  (continued)
                    267

-------
TABLE A-63 .
( continued)

Rate mm/week 25
50 75 TOO
Net
N                               2.53          2.83          3.06         3.54
P                               0.45          0.49          0.51         0.53
K                               1.93          1.55          1.59         1.43
Ca                              0.31          0.38          0.45         0.49
Mg               %              0.23          0.27          0.28         0.29
Na                              0.017         0.015         0.016        0.015
Fe                              0.025         0.019         0.034        0.036
Zn                              _             0             -            -
Mn                              0.0019        0.0010        0.0008       0.0010
Cu                              0.0009        0.0009        0.0010       0.0012
                                    268

-------
                TABLE A-64.  NUTRIENT UPTAKE BY RYE - 1973
Rate	mm/week	25	50	75	100

                                              1st Harvest

N                              40           50           47           65
P                               6.2          7.7          7.5           9.6
K                              21           16           21            19
Ca                              4.6          5.3          6.6           7.9
Mg             kg/ha            2.8          3.8          3.7           4.7
Na                              0.20         0.29         0.21          0.38
Fe                              0.39         0.30         1.13          1.35
Zn                              0.010        0.024        0            0.106
Mn                              0.031        0.017        0.023         0.029
Cu                              0.012        0.014        0.021         0.029

                                              2nd Harvest

N                              12           20           23           19
P                               2.0          2.8          2.9           2.6
K                               6897
Ca                              1.4          2.2          2.6           2.1
Mg             kg/ha            1.0          1.7          1.8           1.4
Na                              0.16         0.13         0.16          0.10
Fe                              0.062        0.095        0.091         0.069
Zn                              0000
Mn                              0.0117       0.0073       0.0057        0.0046
Cu                              0.0039       0.0067       0.0057        0.0046

                                              3rd Harvest
N
P
K
Ca
Mg
Na
Fe
Zn
Mn
Cu
42
9
45
5.7
kg/ha 4.8
0.29
0.48
0
0.030
0.018
78
12
47
9.7
7.0
0.26
0.47
0
0.022
0.022
64
12
40
10.7
6.7
0.32
0.27
0
0.007
0.020
79
13
42
13.2
7.9
0.25
0.28
0
0.014
0.021

                                             'continued'
                                    269

-------
                         TABLE A-64.	(continued)
Rate	mm/week	  25	50	    75          100

                                                 Total

N                              94           148          134          163
P                              17            23           22           25
K                              72            71           70           68
Ca                             12            17           20           23
Mg             kg/ha            8.6          12           12           14
Na                              0.65         0.68         0.69         0.73
Fe                              0.93         0.87         1.49         1.70
Zn                              0.01         0.02         0            0.11
Mn                              0.073        0.046        0.036        0.048
Cu                              0.034        0.043        0.047        0.055
                                    270

-------
TABLE A-65.   NUTRIENT RECOVERY BY RYE - 1973

Rate

N
P
K
Ca
Mg
Na
Fe
Zn

N
P
K
Ca
Mg
Na
Fe
Zn
mm/week 25

94
17
72
12
8.6
0.65
0.93
0.01

160
60
29
170
50
190
2.3
1.0
50
Harvested
148
23
71
17
12
0.68
0.87
0.02
Applied,
320
120
58
340
100
380
4.7
2.1
75
, kg/ha
134
22
70
20
12
0.69
1.49
0
kg/ha
480
180
87
510
150
570
7.0
3.1
100

163
25
68
23
14
0.73
1.70
0.11

640
240
116
680
200
760
9.4
4.2
Recovered , %
N
P
K
Ca
Mg
Na
Fe
Zn
59
28
250
7.1
17
0.34
40
1
46
19
120
5.0
12
0.18
19
1
28
12
80
3.9
8
0.12
21
-
25
10
58
3.4
7
0.10
18
3
                     271

-------
ho
                    IRRIGflTIGN  RflTE,  MM/WEEK
o
o-
                 o:
                 X o
                 o
                 UJ


                 OC
                 CE
                                        = HflRVESTED
                            200

                            N  fiPPLIED,  KG/Hfl
                                                        ,0
                                                        (O
                                                        ,o
                                                          lij
                                                          flC
                                       o
                                       <_>
                                       bj
                      Figure A-22.  Nitrogen recovery by rye - 1973.

-------
Ryegrass

     Increased irrigation rates produced higher yields of green  and  dry  forage
(Table A-66), with a slight decrease in dry matter content.   Nitrogen  content
increased strongly with rate (Table A-67),  while other elements  showed only
moderate changes.   Crop uptake of N showed  a strong upward trend with  appli-
cation rate (Table A-68), while recovery of all  elements  decreased  (Table
A-69).  Figure A-23 shows the curve of diminishing returns for N.
            TABLE A-66.  YIELD AND DRY MATTER OF RYEGRASS    1973
    Rate
mm/week
25
50
75
100
    Green Weight, mtons/ha       4.2
    Dry Matter, %               13.2
    Dry Weight, mtons/ha         0.56
    Green Weight, mtons/ha       6.9
    Dry Matter, %               17.0
    Dry Weight, mtons/ha         1.17
    Green Weight, mtons/ha      17.2
    Dry Matter, %               15.8
    Dry Weight, mtons/ha         2.71
    Green Weight, mtons/ha      28.3
    Dry Matter, %               15.7
    Dry Weight, mtons/ha         4.44
                                               1st Harvest
                           12.4
                           11.2
                            1.39
                        12.5
                        10.2
                         1.27
                                               2nd Harvest
                            8.8
                           15.9
                            1.40
                         9.5
                        15.3
                         1.45
                                               3rd Harvest
                           15,
                           15,
                            2.42
                           37.1
                           14.0
                            5.21
                                                   Net
                        20.3
                        12.6
                         2.56
                        42.3
                        12.5
                         5.28
                        12.9
                        11.4
                         1.48
                         9.7
                        15.0
                         1.45
                        21.4
                        13.8
                         2.95
                        44.0
                        13.4
                         5.88
                                    273

-------
TABLE A-67.   NUTRIENT CONTENT OF  RYEGRASS - 1973

Rate mm/week

N
P
K
Ca
Mg %
Na
Fe
Zn
Mn
Cu

N
P
K
Ca
Mg %
Na
Fe
Zn
Mn
Cu

N
P
K
Ca
Mg %
Na
Fe
Zn
Mn
Cu
25

3.83
0.93
1.71
0.45
0.25
1.30
0.028
0
0.0022
0.0022

2.92
0.80
1.25
0.49
0.27
1.23
0.033
0
0.0010
0.0012

2.11
0.67
1.24
0.63
0.26
1.08
0.013
0
0.0020
0.0008
50
1st Harvest
4.13
0.92
1.71
0.41
0.25
1.61
0.024
0
0.0018
0.0018
2nd Harvest
2.88
0.87
1.47
0.41
0.26
1.61
0.023
0
0.0015
0.0013
3rd Harvest
3.09
0.82
1.49
0.46
0.29
1.25
0.014
0
0.0015
0.0012
75

4.04
0.86
1.68
0.48
0.29
1.58
0.019
0
0.0020
0.0020

3.78
0.77
1.49
0.47
0.28
1.75
0.023
0
0.0015
0.0015

3.36
0.72
1.57
0.49
0.26
1.33
0.013
0
0.0015
0.0012
100

4.12
0.80
1.68
0.44
0.25
1.38
0.037
0
0.0020
0.0020

3.47
0.72
1.49
0.47
0.27
1.74
0.036
0
0.0015
0.0015

3.20
0.66
1.38
0.48
0.25
1.41
0.013
0
0.0015
0.0012
                             (continued)
                       274

-------
                        TABLE A-67 .   (continued)
Rate          mm/week          25          50            75          100

                                                Net

N-                              2.55         3.30         3.37         3.49
P                               0.74         0.86         0.77         0.71
K                               1.30         1.77         1.57         1.48
Ca                              0.57         0.43         0.48         0.47
Mg              %               0.26         0.27         0.28         0.26
Na                              1.15         1.44         1.50         1.48
Fe                              0.020       0.019         0.017        0.025
Zn                              0000
Mn                              0.0017      0.0016        0.0016       0.0016
Cu                              0.0011       0.0014        0.0015       0.0015
                                    275

-------
              TABLE A-68.   NUTRIENT UPTAKE BY RYEGRASS - 1973
Rate	mm/week	25	50	75	100

                                             1st Harvest

N                              21          57           51            61
P                               5.2        13           11            12
K                              10          24           21            25
Ca                              2.5         5.7          6.1            6.5
Mg             kg/ha            1.4         3.5          3.7           3.7
Na                              7.3        22           20            20
Fe                              0.16        0.33         0.24          0.55
Zn                              0000
Mn                              0.012       0.025        0.025         0.030
Cu                              0.012       0.025        0.025         0.030

                                             2nd Harvest

N                              34          40           55            50
P                               9.4        12           11            10
K                              15          21           22            22
Ca                              5.7         5.7          6.8           6.8
Mg             kg/ha            3.2         3.6          4.1            3.9
Na                             14          22           25            25
Fe                              0.39        0.32         0.33          0.52
Zn                              0000
Mn                              0.012       0.021         0.022         0.022
Cu                              0.014       0.018        0.022         0.022

                                             3rd Harvest
N
P
K
Ca
Mg
Na
Fe
Zn
Mn
Cu
57
18
34
17
kg/ha 7.0
29
0.35
0
0.054
0.020
75
20
36
11
7.0
30
0.34
0
0.036
0.029
86
18
40
12
6.7
34
0.33
0
0.038
0.031
94
19
41
14
7.4
42
0.38
0
0.044
0.035
                                           (continued)
                                    276

-------
                         TABLE  A-68.   (Continued)
Rate          mm/week          25          50           75           100

                                                 Total

N                             112         172          192           205
P                              33          45           40            41
K                              59          81           83            88
Ca                             25          22           25            27
Mg             kg/ha           12          14           15            15
Na                             50          74           79            87
Fe                              0.90        0.99         0.90          1.45
Zn                              0000
Mn                              0.078       0.082        0.085          0.096
Cu                              0.046       0.082        0.078          0.087
                                     277

-------
TABLE A-69 .   NUTRIENT  RECOVERY  BY  RYEGRASS  -  1973

Rate

N
P
K
Ca
Mg
Na
Fe
Zn
Mn
Cu

N
P
K
Ca
Mg
Na
Fe
Zn
Mn
Cu
mm/ week 25

112
33
59
25
12
50
0.90
0
0.078
0.046

160
60
29
170
50
190
2.3
1.0
-
-
50
Harvested,
172
45
81
22
14
74
0.99
0
0.082
0.082
Applied,
320
120
58
340
100
380
4.7
2.1
-
-
75
kg/ha
192
40
83
25
15
79
0.90
0
0.085
0.078
kg/ha
480
180
87
510
150
570
7.0
3.1
-
-
100

205
41
88
27
15
87
1.45
0
0.096
0.087

640
240
116
680
200
760
9.4
4.2
-
-
Recovered, %
N
P
K
Ca
Mg
Na
Fe
70
55
205
15
24
26
39
54
38
140
6.5
14
19
21
40
22
95
4.9
10
14
13
32
17
76
4.0
7.5
11
15
                       278

-------
ro
                     1RRIGRTIGN RflTE,  MH/WEEK
                    o
                    o-
                  CT
                  I
                  X
                  o
Q
UJ
5—
4O
yj
                              £00

                                                  100
                                             O s HflRVESTED
                                                             oc
                                                             yj
                                                             >
                                                             o
                                                          -
                      Figure A-23.  Nitrogen recovery by ryegrass - 1973,

-------
1974 SUMMER CROPS

     Crops included pearl  millet (Tiflate and Gahi-1), corn (Pioneer 3369 A )
and coastal bermudagrass.   All  plots were prepared by disking, plowing, and
disking again.   Field operations followed the schedule of Table A-70.   Pearl
millet was planted at the  rate  of 11  kg/ha (10 Ib/acre)  with a cultipacker
seeder.  Corn was planted  in 0.9-m (36-in.)  rows  at a density of approximately
73,000 plants/ha (29,000 plants/acre).   Coastal  bermudagrass was sprigged in
August 1973 at the rate of 25 bales/ha  (10 bales/acre).   Bales of fresh green
coastal bermudagrass  were  distributed over the plots using a manure spreader
and then cut-in by light disking.   Good plot coverage was obtained by  June
1974.  Some weeds were evident  in the first  cutting.

     Characteristics  of the effluent for the period 4/74-9/74 are given in
Table 6.

Pearl Millet - Gahi 1
     Three cuttings were obtained  for the  season.   Green  and  dry yields  as
well as dry matter content,  were all  essentially  independent  of irrigation
rate (Table A-71).   Slight lodging was  evident at  the first harvest for  200
mm/week indicating that the  first  harvest  should  have been  at 6 or 7 weeks
after planting.   A small amount of forage  in  this  plot was  not harvestable.
Nitrogen content showed a small increase with rate (Table A-72).   Values of
N uptake (Table  A-73)  were slightly erratic.   Efficiency  of N recovery  (Figure
A-24) was low due to the high  application  rates of N.   Uptake of K exceeded
application for  all  rates, indicating a potential  for K deficiency.   Recovery
of other elements decreased  with irrigation  rate  (Table A-74).
                                     280

-------
             TABLE A-70.   FIELD SCHEDULE FOR SUMMER 1974
         Crop
                        Planting
                     Harvesting
     Pearl  Millet
           Gahi-1
           Tiflate

     Corn Silage

     Coastal Bermudagrass
                        4/10/74



                        6/12/74

                        3/27/74
                        6/5/74
                       7/31/74
                      10/16/74

                      10/16/74

                        7/3/74

                        6/5/74
                        7/3/74
                       7/31/74
                      10/16/74
  TABLE A-71.   YIELD AND DRY MATTER OF PEARL MILLET (GAHI-1)  -  1974
Rate
mm/week
100
150
200
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
                     38.8
                     13.4
                      5.20
                     40.5
                     19.8
                      8.02
                      9.2
                     26.4
                      2.44
                     88.5
                     17.7
                     15.7
             1st  Harvest

                36.5
                13.6
                 4.97

             2nd  Harvest

                36.7
                19.8
                 7.28

             3rd  Harvest

                10.0
                25.4
                 2.55

                 Net

                83.2
                17.8
                14.8
                41.2
                13.2
                 5.44
                37.6
                20.4
                86.0
                32.0
                 2.76
                87.4
                18.2
                15.9
                                 281

-------
TABLE A-72L.  NUTRIENT CONTENT OF  PEARL MILLET  (GAHI-1)  -  1974

Rate mm/week

N
P
K
Ca
Mg %
Na
Fe
Zn
Al

N
P
K
Ca
Mg %
Na
Fe
Zn
Al

N
P
K
Ca
Mg %
Na
Fe
Zn
Al
TOO

1.74
0.85
1.49
0.52
1.32
0.052
0.016
0.0021
0.0025

1.53
0.52
1.06
0.64
1.09
0.035
0.018
0.0027
0.0050

1.14
0.60
0.95
0.81
0.89
0.025
0.017
0.0028
0.0125
150
1st Harvest
1.71
0.85
1.36
0.50
1.18
0.032
0.021
0.0022
0.0025
2nd Harvest
1.56
0.45
1 .04
0.58
0.91
0.025
0.028
0.0012
0.0025
3rd Harvest
1.67
0.49
1.02
0.88
0.88
0.042
0.015
0.0030
0.0125
200

2.09
0.74
1.28
0.52
1.15
0.172
0.018
0.0026
0.0075

1.63
0.41
1.18
0.61
0.90
0.042
0.016
0.0014
0.0025

1.31
0.50
0.86
0.75
0.43
0.023
0.010
0.0040
0.0075
                                          (continued)
                            282

-------
                          TABLE A-72.  (continued)
jtete	mm/week	100	150	200

                                                      Net

 N                                        1.55            1.63           1.73
 P                                        0.64            0.59           0.54
 K                                        1.19            1.14           1.16
 Ca                                       0.63            0.61           0.60
 Mg               %                       1.00            1.00           0.90
 Na                                       0.039           0.030          0.084
 Fe                                       0.017           0.023          0.015
 Zn                                       0.0025          0.0019         0.0023
 Al                                       0.0054          0.0042         0.0050
                                      283

-------
TABLE A-73.  NUTRIENT UPTAKE BY PEARL MILLET  (GAHI-1)  -  1974

Rate mm/week

N
P
K
Ca
Mg kg/ha
Na
Fe
Zn
Al

N
P
K
Ca
Mg kg/ha
Na
Fe
Zn
Al

N
P
K
Ca
Mg kg/ha
Na
Fe
Zn
Al
100

90
44
77
27
69
2.7
0.83
0.11
0.13

123
42
85
51
87
2.8
1.4
0.22
0.40

28
15
23
20
22
0.61
0.41
0.068
0.31
150
1st Harvest
85
42
68
25
59
1.6
1.04
0.11
0.12
2nd Harvest
73
33
76
42
66
1.8
2.0
0.09
0.18
3rd Harvest
43
12
26
22
22
1.07
0.38
0.077
0.32
200

114
40
70
28
63
9.4
0.98
0.14
0.41

125
31
91
47
69
3.2
1.2
0.11
0.19

36
14
24
21
12
0.63
0.28
0.110
0.21
                           284

-------
                        TABLE A-73 .   (continued)
Rate	mm/week	100	150	200

                                                     Total

N                                     241             201             275
P                                     101              87             85
K                                     185             170            185
Ca                                     98              89             96
Mg             kg/ha                  178             147            144
Na                                      6.1              4.5           13.2
Fe                                      2.6              3.4            2.8
Zn                                      0.40            0.28           0.36
Al                                      0.84            0.62           0.81
                                    285

-------
TABLE A-74.   NUTRIENT RECOVERY  BY  PEARL  MILLET (GAHI-1)  -  1974

Rate mm/week

N
P
K
Ca
Mg
Na

N
P
K
Ca
Mg
Na

N
P
K
Ca
Mg
Na
100

241
101
185
98
178
6.1

840
260
85
670
200
770

29
39
220
14.6
89
0.79
150
Harvested, kg/ha
201
87
170
89
147
4.5
Applied, kg/ha
1260
390
128
1000
300
1150
Recovered, %
16
22
130
8.9
49
0.39
200

275
85
185
96
144
13.2

1680
520
170
1340
400
1540

16
16
no
7.2
36
0.86
                        286

-------
00
                 O
              X
              O
IRBIGflTIGN RflTE.  HM/HiEEK
                 o    .   iso
                       0 s HftRVESTED
                                                         200
                                                                  •
                                                                      *
                                                                     O
                                            I O Lull
                                             <* >
                                               O

                                               Lull
                                               1C
                       Figure A-24.
            Nitrogen recovery by pearl millet
            (Gahi-1) - 1974,

-------
Pearl Millet - Tiflate

     Only one harvest was  obtained,  18 weeks  after planting.   Plots  were
irrigated for only 14 weeks.   Yields of green and  dry  forage  increased with
irrigation rate (Table A-75),  while  dry matter content remained  approximately
constant.  Nitrogen content  showed an increase with rate.   Crop  uptake of N
showed a strong increase with  application  rate (Table  A-76),  while recovery
showed a gradual  decline from  37% at 50 mm/week (Figure A-25).   Again, K
uptake exceeded application.
     TABLE A-75.   YIELD  AND  COMPOSITION  OF  PEARL MILLET  (TIFLATE)  -  1974
    Rate
mm/week
50
100
150
    Green Weight,  mtons/ha
    Dry Matter,  %
    Dry Weight,  mtons/ha
    N
    P
    K
    Ca               %
    Mg
    Na
    Fe
    Zn
    Al
                  34
                  29
                  10
   3
   4
   1
 0.94
 0.55
 0.60
 0.40
 0.45
 0.020
 0.0105
 0.0042
 0.0050
 53.8
 26.8
 14.4
  1.10
  0.26
  0.72
  0.40
  0.44
  0.030
  0.0112
  0.0035
  0.0075
 60
 27
 16
  1
  7
  2
  5
  25
0.42
0.71
0.42
0.45
0.032
0.0162
0.0036
0.0150
                                    288

-------

TABLE A-76. NUTRIENT RECOVERY BY PEARL
MILLET (TIFLATE)
- 1974

Rate

N
P
K
Ca
Mg
Na
Fe
Zn
Al

N
P
K
Ca
Mg
Na
Fe
Zn
Al

N
P
K
Ca
Mg
Na
mm/ week 50

95
56
61
40
45
2.0
1.1
0.42
0.51

260
78
26
200
62
235
-
-
-

37
72
230
20
73
0.85
100
Harvested, kg/ha
158
37
104
58
63
4.3
1.6
0.50
1.1
Applied, kg/ha
520
156
52
400
124
470
-
-
-
Recovered, %
30
24
200
15
50
0.91
150

206
69
117
69
74
5.3
2.7
0.59
2.5

780
234
78
600
186
705
-
-
-

26
29
150
12
40
0.75
289

-------
ro
UD
o
                    IRRIGfiTI
                o
                o-
              cc
              o
                o
                o
               . 
                               o

                               uj
                               or
                           1000
                        Figure A-25.  Nitrogen recovery by pearl  millet
                                  (Tiflate) - 1974.

-------
Corn Silage

     The corn was harvested at the hard dent stage,  14 weeks  after  planting.
Green and dry yields showed a strong increase with irrigation rate  (Table
A-77), while dry matter content was approximately constant.   Nitrogen  content
showed a slight increase with rate.  A large increase in crop N  with appli-
cation rate was obtained (Table A-78), but recoveries of N were  low (Figure
A-26) due to the high application rates.
          TABLE A-77.  YIELD AND COMPOSITION OF CORN  SILAGE  -  1974

Rate mm/week
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
N
P
K
Ca %
Mg
Na
Fe
Zn
Al
100
20.0
28.0
5.58
1.18
0.37
0.27
0.31
0.27
0.038
0.024
0.0030
0.0050
150
25.2
27.2
6.83
1.29
0.39
0.26
0.36
0.31
0.035
0.015
0.0015
0.0025
200
31.5
30.0
9.43
1.26
0.35
0.26
0.26
0.24
0.035
0.011
0.0010
0.0025
                                    291

-------
TABLE A-78.  NUTRIENT RECOVERY BY CORN SILAGE - 1974

Rate mm/week

N
P
K
Ca
Mg
Na
Fe
Zn
Al

N
P
K
Ca
Mg
Na
Fe
Zn
Al

N
P
K
Ca
Mg
Na
100

66
21
15
17
15
2.1
1.3
0.17
0.28

510
155
52
403
123
470
-
_
-

13
14
29
4.2
12
0.45
150
Harvested, kg/ha
88
27
18
25
21
2.4
1.0
0.10
0.17
Applied, kg/ha
765
232
78
604
185
705
_
_
-
Recovered, %
12
12
23
4.1
11
0.34
200

119
33
25
25
23
3.3
1.1
0.094
0.24

1020
310
104
806
246
940
_
_
-

12
11
24
3.1
9
0.35
                         292

-------
ro
UD
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                    IRRIGATION  RATE,  HM/NEEK

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50 100 i|0 200

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O
ex
*l
BO f"ii
01 UJI
UJI
o
=o y

- z
-o
                                           7SO

                     Figure A-26.  Nitrogen recovery by corn silage - 1974.

-------
Coastal Bermudagrass

     This grass responded very well  to  irrigation  with  effluent.   Some prob-
lem with  weeds in the plots  was  experienced.   Four cuttings  were obtained
(Table A-79).   Yields of green and dry  forage  increased with  irrigation rate,
while dry matter content showed a slight decline.   Nitrogen  content showed
an increase with rate (Table  A-80).   Nitrogen  levels in the  last  cutting were
low because of the age of the grass;  viz,  11 weeks.   Better  forage quality
would have been obtained at an earlier  age, yielding 5  cuttings  instead of 4.
Crop uptake of N showed a general  increase with application  rate  (Tables A-81
and A-82).  Recovery efficiency exhibited  the  trend of  diminishing returns
(Figure A-27), from a value of 49% at 50 mm/week.
      TABLE A-79.  YIELD AND DRY MATTER OF COASTAL BERMUDAGRASS - 1974
    Rate
mm/week
50
100
          150
200
    Green Weight, mtons/ha
    Dry Matter, %
    Dry Weight, mtons/ha
    Green Weight, mtons/ha
    Dry Matter, %
    Dry Weight, mtons/ha
    Green Weight, mtons/ha
    Dry Matter, %
    Dry Weight, mtons/ha
    Green Weight, mtons/ha
    Dry Matter, %
    Dry Weight, mtons/ha
    Green Weight, mtons/ha
    Dry Matter,  %
    Dry Weight,  mtons/ha
                   10.3
                   20.0
                    2.07
                    6.3
                   24.4
                    1.54
                    7.5
                   25.6
                    1.91
                   10.9
                   46.0
                    5.03
                   35.0
                   30.3
                   10.6
                                                 1st Harvest
16.1
16.4
 2.63
           43.2
           25.7
           11.1
            13.9
            19.6
             2
  8.8
 25.4
  2.23
                                                 3rd  Harvest
            8.6
           25.4
            2.19
            9.7
           42.0
            4.05
                                                     Net
                         73
                                                 2nd Harvest
                      12.1
                      26.4
                       3.19
             9.6
            25.2
             2.41
                                                 4th  Harvest
            12.4
            40.6
             5.05
            48.0
            27.9
            13.4
 13.1
 20.0
  2.62
                      14.4
                      24.0
                       3.46
                      12.3
                      23.6
                       2.91
                      11.8
                      43.6
                       5.16
                      51 .6
                      27.4
                      14.2
                                    294

-------
TABLE A-80.   NUTRIENT CONTENT OF COASTAL BERMUDAGRASS - 1974
Rate

N
P
K
Ca
Mg
Na
Fe
Zn
Al

N
P
K
Ca
Mg
Na
Fe
Zn
Al

N
P
K
Ca
Mg
Na
Fe
Zn
Al

N
P
K
Ca
Mg
Na
Fe
Zn
Al
mm/week 50

1.95
0.37
1.53
0.88
% 0.33
0.13
0.014
0.0071
0.0050

1.96
0.35
1 .50
0.73
% 0.30
0.070
0.021
0.0030
0.0050

1.59
0.37
1.53
0.56
% 0.30
0.055
0.012
0.0019
0.0025

0.49
0.28
0.78
0.45
% 0.21
0.032
0.0062
0.0018
0.0075
100 1
1st Harvest
2.57
0.37
1.80
0.89
0.33
0.26
0.019
0.0040
0.0050
2nd Harvest
2.79
0.37
1.75
0.66
0.36
0.105
0.011
0.0018
0.0050
3rd Harvest
1.85
0.34
1.60
0.55
0.34
0.062
0.010
0.0010
0.0025
4th Harvest
0.56
0.25
1 .09
0.54
0.27
0.045
0.0112
0.0015
0.0125
50

2.57
0.37
1.73
0.72
0.30
0.20
0.017
0.0043
0.0050

2.43
0.36
1.69
0.58
0.34
0.095
0.014
0.0016
0.0050

2.01
0.32
1.45
0.53
0.34
0.058
0.015
0.0012
0.0100

0.70
0.24
0.89
0.45
0.23
0.040
0.0062
0.0009
0.0075
200

2.82
0.37
0.73
0.81
0.35
0.22
0.016
0.0038
0.0050

2.80
0.40
1.79
0.58
0.34
0.095
0.014
0.0018
0.0050

2.18
0.38
1.66
0.60
0.40
0.058
0.016
0.0016
0.0125

0.90
0.24
1.02
0.50
0.27
0.035
0.0078
0.0015
0.0100

                                          (continued)
                              295

-------
                         TABLE  A-80.   (continued)
Rate	mm/week	50	TOO	150	200

                                                  Net

N                               1.18         1.74          1.73          1.98
P                               0.32         0.32          0.31          0.33
K                               1.16         1.49          1.35          1.47
Ca                              0.59         0.65          0.55          0.60
Mg               %              0.26         0.32          0.29          0.41
Na                              0.061         0.111         0.089         0.088
Fe                              0.011         0.013         0.012         0.013
Zn                              0.0030        0.0021        0.0018        0.0020
Al                              0.0057        0.0072        0.0082        0.0083
                                    296

-------
	TABLE A-81 .  NUTRIENT UPTAKE BY COASTAL BERMUDA6RASS - 1974	


Rate	mm/week	50	TOO	150	200

                                              1st Harvest

N                              40           68           70           74
P                                7.7          9.7         10.1          9.7
K                              32           47           47           45
Ca                             18           23           20           21
Mg             kg/ha             6.8          8.7          8.2          9.2
Na                               2.7          6.8          5.5          5.8
Fe                               0.29         0.50         0.46         0.42
Zn                               0.15         0.11         0.12         0.10
Al                               0.10         0.13         0.14         0.13

                                              2nd Harvest

N                              30           62           78           35
P                                5.4          8.3         11.5         13.8
K                              23           39           54           62
Ca                             11           15           19           20
Mg             kg/ha             5            8           11           12
Na                               1.1          2.3          3.0          3.3
Fe                               0.32         0.25         0.45         0.48
Zn                               0.050        0.040        0.051        0.062
Al                               0.08         0.11         0.16         0.17

                                              3rd Harvest

N                              30           41           48           63
P                                7.1          7.4          7.7         11.1
K                              29           35           35           48
Ca                             11           12           13           17
Mg             kg/ha             5.7          7.4          8.2         11.6
Na                               1.1          1-4          1.4          1.7
Fe                               0.23         0.22         0.36         0.47
Zn                               0.036        0.022        0.029        0.047
Al                               0.05         0.05         0.24         0.36

                                              4th Harvest

N                              80           23           35           46
P                              14           10           12           12
K                              329           44           45           53
Ca                             23           22           23           26
Mg             kg/ha           11           11           12           14
Na                               1.6          1.8          2.0           1.8
Fe                               0.31         0.45         0.31          0.40
Zn                               0.090        0.061        0.045         0.077
Al                               0.38         0.51         0.38          0.52
                                     297

-------
	TABLE' A-82.   NUTRIENT RECOVERY  BY  COASTAL BERMUDAGRASS - 1974	


Rate          mm/week          50           100          150          200

                                           Harvested,  kg/ha

N                             180           194          231          218
P                              34            35           41           47
K                             123           165          181          208
Ca                             63            72           75           84
Mg                             29            35           39           47
Na                              6.5          12           12           13
Fe                              1.2          1.4          1.6          2.0
Zn                              0.33         0.23         0.24         0.28
Al                              0.61         0.80         0.92         1.18

                                            Applied, kg/ha

N                             365           730         1095         1460
P                             112           224          336          448
K                              37            74          111          148
Ca                            290           580          870         1160
Mg                             87           174          261          348
Na                            335           670         1005         1340
Fe                             -
Zn                             -
Al                             -

                                            Recovered, %

N                              49            27           21           15
P                              30            16           12           10
K                             330           220          160          140
Ca                             22            12            9            7
Mg                             33            20           15            4
Na                              1.9          1.8          1.2          1.0
                                   298

-------
ho
UD
o


  a  ^
Q

8—
                     o-
                                                                            250
                                                                                   •
                                                                                         XI
                                                                                      yji
                                                           © =  HIRRVES1ED
                                   Hh
                                       N
                        Figure A-27.   Nitrogen  recovery  by  coastal bermudagrass - 1974,

-------
1974 WINTER CROPS

     Rye and ryegrass  were  seeded  at rates  of 0.5  hi/ha  (1/2  bu/acre)  and
0.9 hl/ha (1 bu/acre), respectively, with a cultipacker  seeder.   Plots were
prepared by disking,  plowing  and disking again before  planting.   Two  cuttings
of both crops were  obtained.

     Characteristics  of the effluent for the period  10/74-3/75  are  given in
Table 6.

Rye

     Green and dry  yields both  increased slightly  with irrigation rate (Table
A-83).   Dry matter  content  was  approximately constant.   More  than 80%  of the
forage harvested was  collected  in  the second cutting;  growth  was  more  vigorous
after the first harvest.  Nitrogen content  increased with  rate  (Table  A-84).
Nitrogen uptake also  showed an  increase  (Table A-85).  Due to the high levels
of application (Table  A-86),  recovery of N  was low.  Recovery did follow the
downward trend (Figure A-28)  generally observed.
               TABLE A-83.   YIELD  AND  DRY  MATTER OF  RYE  -  1974
    Rate
mm/week
50
75
100
    Green Weight,  mtons/ha
    Dry Matter,  %
    Dry Weight,  mtons/ha
    Green Weight,  mtons/ha
    Dry Matter,  I
    Dry Weight,  mtons/ha
    Green Weight,  mtons/ha
    Dry Matter,  %
    Dry Weight,  mtons/ha
                      3.00
                     16.4
                      0.49
                     13.8
                     19.0
                      2.61
                     16.8
                     18.5
                      3.1
            1st Harvest

                2.78
               17.5
                0.49

            2nd Harvest

               15.7
               19.7
                3.10

                Net

               18.5
               19.4
                3.6
                3.99
               16.1
               0.64
               14.9
               18.5
                2.75
               18.9
               17.9
                3.4
                                    300

-------
                TABLE A-84 .  NUTRIENT CONTENT OF RYE -  1974
Rate mm/ week

N
P
K
Ca
Mg %
Na
Fe
Zn
Al
50

3.82
0.70
1.80
0.51
0.27
0.030
0.024
0.0065
0.0100
75
1st Harvest
3.72
0.70
1.96
0.54
0.26
0.025
0.020
0.0030
0.0125
100

4.26
0.67
1.84
0.61
0.27
0.060
0.028
0.0052
0.0275
                                               2nd Harvest

N                                      2.57           2.62            2.89
P                                      0.46           0.44            0.45
K                                      2.00           2.05            2.14
Ca                                     0.41           0.42            0.49
Mg               %                     0.23           0.23            0.23
Na                                     0.040          0.038           0.045
Fe                                     0.0210         0.0225          0.0188
Zn                                     0.0034         0.0052          0.0045
Al                                     0.0050         0.0075          0.0100

                                                   Net

N                                      2.76           2.77            3.15
P                                      0.50           0.48            0.49
K                                      1.96           2.04            2.09
Ca                                     0.42           0.63            0.51
Mg               %                     0.24           0.23            0.24
Na                                     0.038          0.036           0.048
Fe                                     0.0212         0.0222          0.0205
Zn                                     0.0039         0.0049          0.0036
Al                                     0.0058         0.0082          0.0133
                                     301

-------
TABLE A-85.   NUTRIENT UPTAKE BY RYE - 1974

Rate mm/ week

N
P
K
Ca
Mg kg/ha
Na
Fe
Zn
AT

N
P
K
Ca
Mg kg/ha
Na
Fe
Zn
Al

N
P
K
Ca
Mg kg/ha
Na
Fe
Zn
Al
50

19
3.4
8.8
2.5
1.3
0.15
0.11
0.032
0.049

67
12
52
11
6.0
1.0
0.55
0.089
0.13

86
15
61
14
7.3
1.2
0.66
0.12
0.18
75
1st Harvest
18
3.4
9.6
2.6
1.3
0.12
0.10
0.015
0.061
2nd Harvest
81
14
64
13
7.1
1.2
0.70
0.16
0.23
Total
99
17
74
16
8.4
1.3
0.80
0.18
0.29
100

27
4.3
11.8
3.9
1.7
0.38
0.18
0.033
0.176

79
12
59
13
6.3
1 .2
0.52
0.12
0.28

106
16
63
17
8.0
1.6
0.70
0.15
0.46
                    302

-------
               TABLE A-86.  NUTRIENT RECOVERY BY RYE - 1974
Rate          mm/week                 50            75             100

                                             Harvested, kg/ha

N                                     86            99             106
P                                     15            17              16
K                                     61            74              63
Ca                                    14            16              17
Mg                                     7.3           8.4             8.0
Na                                     1.2           1.3             1.6
Fe                                     0.66          0.80            0.70
Zn                                     0.12          0.18            0.15
Al                                     0.18          0.29            0.46

                                              Applied, kg/ha

N                                    455           682             910
P                                    100           150             200
K                                     45            68              90
Ca                                   320           480             640
Mg                                   112           168             224
Na                                   280           420             560
Fe                                     2.0           3.0             4.0
Zn                                     3.6           5.4             7.2
Al                                    -

                                              Recovered, %

N                                     19            15              12
P                                     15            11               8
K                                    140           110              70
Ca                                     4.4           3.3             2.7
Mg                                     6.5           5.0             3.6
Na                                     0.43          0.31            0.29
Fe                                    33            27              18
Zn                                     3.3           3.3             2.1
                                     303

-------
OJ
o
               ©'
               Iflr
               o
             O
O
yj  J.

to

> g
cc
oc
                      IRRIGftTION  RfiTE,  MM/WEEK
                                           © = HRRVESTED
                        200
                            N  flPPLIED,
                                                               ac
                                                               UJ!
                                                               o
                                                               UJ
                      Figure A-28.  Nitrogen recovery by rye - 1974.

-------
Ry_eg_rass

     Green and dry yields were somewhat erratic (Table A-87),  and showed no
definite trend.  Dry matter content did show an increase with  rate.   Nitrogen
content (Table A-88) did not show a definite trend.   Nitrogen  uptake  showed  a
slight upward trend with application rate (Table A-89), with a corresponding
decrease in N recovery (Figure A-29).   Recovery of N was low due to  the  high
application rates of N (Table A-90).
            TABLE A-87.   YIELD AND DRY MATTER OF RYE6RASS - 1974
    Rate
mm/week
50
75
100
    Green Weight, mtons/ha
    Dry Matter, %
    Dry Weight, mtons/ha
    Green Weight,  mtons/ha
    Dry Matter, %
    Dry Weight, mtons/ha
    Green Weight,  mtons/ha
    Dry Matter,  %
    Dry Weight,  mtons/ha
                      6.76
                     13.6
                      0.92
                     19.0
                     12.8
                      2.43
                     25.8
                     13.0
                      3.35
            1st Harvest

                7.66
               14.4
                1.10

            2nd Harvest

               26.4
               13.4
                3.53

                Net

               34.1
               13.6
                4.63
                7.77
               12.0
                0.93
               18.0
               15.2
                2.73
               25.8
               14.2
                3.66
                                     305

-------
              TABLE A-88.  NUTRIENT CONTENT OF RYEGRASS - 1974

Rate mm/week

N
P
K
Ca
Mg %
Na
Fe
Zn
Al
50

3.80
0.85
2.06
0.45
0.24
1.14
0.018
0.0048
0.0050
75
1st Harvest
3.62
0.75
2.00
0.47
0.23
1.00
0.034
0.0055
0.0050
100

4.12
0.84
2.18
0.41
0.24
1.29
0.039
0.0065
0.0125
N
P
K
Ca
Mg
Na
Fe
Zn
Al
2.57
0.58
1.66
0.50
0.24
1.25
0.035
0.0194
0.0125
2nd Harvest

      2.56
      0.60
      1.71
      0.50
      0.23
      1.31
      0.071
      0.0056
      0.0075
3.05
0.58
1 .99
0.50
0.25
1.10
0.026
0.0109
0.0175
                                                   Net
P
K
Ca
Mg
Na
Fe
Zn
Al
2.89
0.65
1 .76
0.48
0.24
1.21
0.030
0.0153
0.0103
      2.80
      0.64
      1.78
      0.49
      0.23
      1.24
      0.062
      0.0056
      0.0070
3.32
0.65
2.03
0.48
0.25
1.14
0.030
0.0098
0.0162
                                     306

-------
TABLE A-89.  NUTRIENT UPTAKE BY RYEGRASS - 1974
Rate mm/ week

N
P
K
Ca
Mg kg/ha
Na
Fe
Zn
Al

N
P
K
Ca
Mg kg/ha
Na
Fe
Zn
Al

N
P
K
Ca
Mg kg/ha
Na
Fe
Zn
Al
50

35
7.8
19
4.1
2.2
10
0.17
0.044
0.046

62
14
40
12
5.8
30
0.85
0.47
0.30

97
22
59
16
8.0
40
1.0
0.51
0.35
75
1st Harvest
40
8.2
22
5.2
2.5
11
0.37
0.060
0.055
2nd Harvest
90
21
60
18
8.1
46
2.51
0.20
0.26
Total
130
29
82
23
10.6
57
2.9
0.26
0.32
100

38
7.8
20
3.8
2.2
12
0.36
0.060
0.116

83
16
54
14
6.8
30
0.71
0.30
0.48

121
24
74
18
9.0
42
1.1
0.36
0.60
                      307

-------
TABLE A-90 .  NUTRIENT RECOVERY BY RYEGRASS - 1974

Rate mm/week

N
P
K
Ca
Mg
Na
Fe
Zn
Al

N
P
K
Ca
Mg
Na
Fe
Zn
Al

N
P
K
Ca
Mg
Na
Fe
Zn
50

97
22
59
16
8.0
40
1.0
0.51
0.35

455
100
45
320
112
280
2.0
3.6
-

21
22
130
5.0
7.1
14
50
14.2
75
Harvested, kg/ha
130
29
82
23
10.6
57
2.9
0.26
0.32
Applied, kg/ha
682
150
68
480
168
420
3.0
5.4
-
Recovered, %
19
19
120
4.8
6.3
14
97
14.8
100

121
24
74
18
9.0
42
1.1
0.36
0.60

910
200
90
640
224
560
4.0
7.2
-

13
12
82
2.8
4.0
8
28
5.0
                       308

-------
CO
o
O
U>
                  J
              I
              X
              o
              a—
              to
                tf>
IRRIGATION RATE,  MM/WEEK

-I    ?    I    T-H-
4s-
1?

                                                     ESTED
                                                                s
                                                                8
                                                                   yji
                                                  •..:
                                                  flC
                              N
                       Figure A-29.  Nitrogen recovery by ryegrass - 1974,

-------
 1975 SUMMER CROP

     For this period only coastal bermudagrass was studied.  In the summer of
 1973 a 1.35 ha (3.34 acres) strip of coastal bermudagrass was sprigged at the
 same time and in the manner as the plots.  The strip was irrigated with water
 from 4 large guns at an average intensity of 28 mm/hr (1.1 in./hr) for 4 hours
 for an irrigation rate of 112 mm/week (4.4 in./week).  This area had not been
 irrigated previously and thus had less weed infestation than the plots.

     All plots and the strip were clipped on April 2, 1975, to remove any early
 weeds.  Some weeds were evident in the 50 mm/week plot at the first and second
 harvests, so these plots were simply clipped without weighing the material.
 Plots and strip were harvested by the schedule shown in Table A-91.

     Effluent characteristics for the period 4/75-9/75 are given in Table 6.



                TABLE A-91.   HARVEST SCHEDULE FOR SUMMER 1975

                                          Coastal  Bermudagrass
           Harvest
1
2
3
4
5
6
4/30/75
6/5/75
6/25/75
8/6/75
9/10/75
-
4/30/75
6/5/75
6/25/75
8/6/75
9/10/75
10/21/75
           Total Time, weeks              23               29
Coastal Bermudagrass Plots

     The plots were harvested 5 times during the season.   Due to light weed
infestation, vegetation from the 50 mm/week was  not saved for the first and
second harvests.   Thus, values for this  rate are somewhat low.   With this  in
mind, it may be seen that dry yields increased only slightly with irrigation
rate (Table A-92), as did dry matter content.   Nitrogen content appeared
somewhat uniform with rate (Table A-93).   Nitrogen  uptake showed only modest
increase with application rates from 100  to 200 mm/week (Table A-94).  The
value of nutrient uptake at 50 mm/week was adjusted by assuming that 40% of
total uptake occurred in the first two cuttings  (based on results for the
other irrigation rates).  Adjusted values  are given in Table A-95.   Based  on
these values N recovery declined downward  from 44%  at 50 mm/week (Figure
A-30).   At this rate K uptake exceeded application, indicating potential
deficiency in long term operation.
                                    310

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  JABLE A-92.  YIELD AND DRY MATTER OF COASTAL BERMUDAGRASS (PLOTS)  - 1975
Rate
mm/week
50
100
                                                        150
200
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
Green Weight, mtons/ha
Dry Matter, %
Dry Weight, mtons/ha
                  6.99
                 24.0
                  1.68
                  5.24
                 27.6
                  1.46
                  3.70
                 26.5
                  0.99
                 15.9
                 26.0
                  4.13
                                              1st Harvest
                               2.97
                              20.0
                               0.60
                           1.43
                          28.8
                           0.40
               2nd Harvest

              9.77       10.7
             24.6        30.8
              2.40         3.29

               3rd Harvest

              6.88         5.64
             25.0        33.5
              1.72         1.88

               4th Harvest

              7.10         5.44
             26.0        33.4
              1.84         1.81

               5th Harvest
             4.61
             23.8
             1.10
             31.3
             24.5
              7.66
                                                   Net
              3.38
             40.4
              1.37
             26.6
             32.9
              8.75
                            1.95
                           26.4
                            0.52
                                                       11.2
                                                       31.2
                                                        3.49
                           6.27
                          30.7
                           1.93
                           4.84
                          29.0
                           1.41
  4.84
 30.8
  1.48
 29.1
 30.3
  8.83
                                     311

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   TABLE A-93 .   NUTRIENT CONTENT OF COASTAL BERMUDAGRASS (PLOTS)  -  1975


Rate          mm/week	   50          100	^50	200

                                              1st Harvest

N                              -             3.05         3.04          3.29
P                              -             0.41         0.31          0.34
K                              -             1.76         1.50          1.58
Ca               %             -             1.22         0.72          0.72
Mg                             -             0.34         0.27          0.26
Na                             -             0.258        0.092         0.068
Fe                             -             0.0230        0.0155        0.0100
Zn                             -             0.0048        0.0033        0.0029

                                             2nd- Harvest

N                              -             2.45         2.27          2.50
P                              -             0.31          0.33          0.34
K                              -             1.45         1.95          1.68
Ca               %             -             1.04         1.02          1.16
Mg                             -             0.30         0.23          0.26
Na                             -             0.118        0.075         0.052
Fe                             -             0.0100        0.0128        0.0122
Zn                             -             0.0033        0.0031        0.0027

                                             3rd Harvest

N                               2.49          2.09         2.53          2.83
P                               0.35          0.40         0.29          0.27
K                               1.51          1.65         1.62          li.60
Ca               %              0.78          0.88         0.54          0.56
Mg                              0.31          0.28         0.26          0.25
Na                              0.092         0.108        0.052         0.050
Fe                              0.0215        0.0130        0.0108        0.0108
Zn                              0.0042        0.0041        0.0026        0.0023

                                             4th Harvest
N
P
K
Ca
Mg
Na
Fe
Zn
1.90
0.40
1.32
% 0.55
0.27
0.032
0.0420
0.0075
2.42
0.34
1.41
0.59
0.30
0.070
0.0125
0.0029
2.25
0.29
1.48
0.54
0.26
0.030
0.0232
0.0054
1.86
0.29
1.58
0.65
0.27
0.062
0.0205
0.0060
                                                  (continued)
                                     312

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                         TABLE A-93.   (continued)
Rate	mm/week	50	100	150	200

                                              5th Harvest
P
K
Ca               %
Mg
Na
Fe                              0.0235       0.0218       0.0180       0.0280
Zn                              0.0037       0.0024       0.0017       0.0033
N
P
K
Ca
Mg
Na
Fe
Zn
2.39
0.42
1.26
0.75
0.32
0.050
3.11
0.31
1.32
0.84
0.32
0.105
3.00
0.25
1.10
0.50
0.27
0.045
3.50
0.30
1.41
0.81
0.31
0.05
                                                    Net
2.28
0.38
1.39
0.71
0.30
0.060
0.0300
0.0054
2.49
0.56
2.24
0.89
0.29
0.112
0.0132
0.0034
2.48
0.31
1.61
0.73
0.26
0.056
0.0153
0.0033
2.68
0.32
1.60
0.86
0.27
0.055
0.0165
0.0033
                                    313

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     TABLE A-94.  NUTRIENT UPTAKE BY COASTAL BERMUDAGRASS (PLOTS)  - 1975


Rate          mm/week          50          100          150          200
                                             1st Harvest

N                              -            18           12           17
P                              -             2.5          1.2          1.8
K                              -            11             6.0          8.2
Ca             kg/ha           -             7.3          2.9          3.7
Mg                             -             2.0          1.1           1.4
Na                             -             1.55         0.37          0.35
Fe                             -             0.14         0.062         0.052
Zn                             -             0.029         0.013         0.015

                                             2nd Harvest

N                              -            59            33           35
P                              -             7.4         10.9          11.9
K                                           35            64           59
Ca             kg/ha           -            25            34           40
Mg                             -             7.2          7.6           9.1
Na                             -             2.8          2.5           1.8
Fe                             -             0.24         0.42          0.43
Zn                             -             0.079         0.102         0.094

                                             3rd Harvest

N                              42            36            48           55
P                               5.9           6.9          5.5           5.2
K                              25            28            30           31
Ca             kg/ha           13            15            10           11
Mg                              5.2           4.8          4.9           4.8
Na                              1.5           1.9          1.0           1.0
Fe                              0.36          0.22         0.20          0.21
Zn                              0.071         0.071         0.049         0.044

                                             4th Harvest
N
P
K
Ca
Mg
Na
Fe
Zn
28
5.8
19
kg/ha 8.0
3.9
0.47
0.61
0.11
45
6.3
26
10.9
5.5
1.29
0.23
0.05
41
5.2
27
9.8
4.7
0.54
0.42
0.10
26
4.1
22
9.2
3.8
0.87
0.29
0.08

                                               (continued)
                                    314

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                           TABLE A-94.  (continued)
Rate	mm/week	50	TOO	150	200

                                             5th Harvest

N                              24           34           41            52
P                               4.2          3.4          3.4          4.4
K                              12           15           15           21
Ca             kg/ha            7.4          9.2          6.9         12.0
Mg                              3.2          3.5          3.7          4.6
Na                              0.50         1.16         0.61          0.77
Fe                              0.23         0.24         0.25          0.41
Zn                              0.037        0.026        0.023        0.049

                                                  Total

N                              94          192          175          185
P                              16           27           26           27
K                              56          115          142          141
Ca             kg/ha           28           67           64           76
Mg                             12           23           22           24
Na                              2.5         11.3          5.0          4.8
Fe                              1.2          2.3          1.4          1.4
Zn                              0^22         o!l8         0.28          0.28
                                    315

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TABLE
Rate

N
P
K
Ca
Mg
Na
Fe
Zn

N
P
K
Ca
Mg
Na
Fe
Zn
A-95. NUTRIENT RECOVERY BY COASTAL BERMUDAGRASS (PLOTS)
rim/week 50

155
26
95
48
20
4.1
2.0
0.37

350
105
67
320
no
380
4.5
2.1
100
Harvested,
192
27
115
67
23
11.3
2.3
0.18
Applied,
700
210
134
640
220
760
9.0
4.2
150
kg/ha*
175
26
142
64
22
5.0
1.4
0.28
kg/ha
1050
315
201
960
330
1140
13.5
6.3
- 1975
200

185
27
141
76
24
4.8
1.4
0.28

1400
420
268
1280
440
1520
18.0
8.4
Recovered, %
N
P
K
Ca
Mg
Na
Fe
Zn
44
25
140
15
18
1.1
44
18
27
13
86
10
10
1.5
26
4.3
17
8.3
71
6.7
6.7
0.4
10
4.4
13
6.4
53
5.9
5.5
0.3
8
3.3

*Value at 50 mm adjusted for 1st two  harvests.
                                    316

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     IRRIGATION  RfiTE,  HH/NEEK

an
cc
X o
0 ^
m
*
O
s Sr
11"™ f^J
CO
yj
X 0-
BS
SO 1 00 1 SO 200 250
1 I 1 1
0 STRIP
m KB

B ^
\
0-^N^^^
\^ PLOTS
m ^^""'v. ^
G = HRRVESTED
	 IL. — 8 II » II 6 II j 	 II 	
O
CO
•
m «i ^t_8]

. Qi
LLJl
01
.0 UJ
3F Sl*ii,
•" .^•"
0'
o
= 1 p II
tJiJi
li;

        100
800
1200
iOOO
Figure A-30. Nitrogen recovery by coastal bermudagrass - 1975,

-------
Coastal  Bermuda Strip

     Six cuttings  were  obtained.   Yield  of  oven  dried  forage was  15.2 mton/
ha, with an average dry matter  content in the  field  of 28.4%  (Table  A-96).
Nitrogen content averaged  2.36%.   Nutrient  uptake  values  for the  various
cuttings are given in Table  A-97.   Recovery efficiencies  for all  elements  are
given in Table A-98.  The  value for N was low  due  to the  high  application  rate
of 1000  kg/ha (890 lb/acre).  Even at this  high  irrigation  rate,  K uptake
slightly exceeded  application.   Other elements appeared quite  adequate.
  TABLE A-96.   YIELD  AND  COMPOSITION  OF COASTAL BERMJDAGRASS  (STRIP) -  1975
Harvest
Green Weight,
mtons/ha
Dry Matter, %
Dry Weight,
mtons/ha
N
P
K
Ca
Mg
Na
Fe
Zn
1
2.2
28.8
0.63
2.49
0.32
1 .54
0.57
0.25
0.062
0.0190
0.0046
2
13.4
27.9
3.71
2.49
0.35
1.56
0.59
0.28
0.089
0.0035
0.0054
3
8.8
27.4
2.42
2.58
0.33
1.53
0.62
0.30
0.079
0.0198
0.0058
4
13.0
28.5
3.72
1.83
0.30
1.24
0.48
0.28
0.040
0.0097
0.0046
5
10.0
27.5
2.76
2.80
0.30
1.27
0.51
0.29
0.062
0.0149
0.0031
6
6.3
31.7
1.99
2.12
0.31
1.31
0.55
0.30
0.050
0.0206
0.0025
Net
53.7
28.4
15.2
2.36
0.32
1.39
0.55
0.29
0.065
0.0263
0.0044
                                    318

-------
 TABLE A-97.  NUTRIENT UPTAKE BY COASTAL BERMUDAGRASS (STRIP) - 1975

Harvest
1
2
3
4
5
6
Total
Harvested, kg/ha
N
P
K
Ca
Mg
Na
Fe
Zn
16
2.0
10
3.6
1.6
0.39
0.12
0.029
93
12.9
58
22
10.5
3.3
2.21
0.20
62
8.1
37
15
7.3
1.9
0.48
0.14
67
11.2
46
18
10.3
1.5
0.36
0.17
77
8.4
35
14
8.0
1.7
0.41
0.085
43
6.2
26
11
6.0
1.0
0.41
0.050
357
49
212
84
44
9.9
4.0
0.67

TABLE A-98.  NUTRIENT RECOVERY BY COASTAL BERMUDAGRASS (STRIP)  - 1975
Element
N
P
K
Ca
Mg
Na
Fe
Zn
Harvested
kg/ha
357
49
212
84
44
9.9
4.0
0.67
Applied
kg/ha
1000
300
190
910
310
1090
12.5
5.9
Recovered
%
35
16
110
9.2
14
0.91
32
11
                                 319

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                                   TECHNICAL REPORT DATA
                            (Please read Instructions on the reverse before completing)
 1. REPORT NO.

   EPA-600/2-79-151
 4. TITLE AND SUBTITLE
   WASTEWATER IRRIGATION  AT  TALLAHASSEE, FLORIDA
             5. REPORT DATE
                August  1979  issuing date_
                                                           6. PERFORMING ORGANIZATION CODE
                                                           3. RECIPIENT'S ACCESSI ON-NO.
 7. AUTHOR(S)
   Allen R. Overman
                                                           8. PERFORMING ORGANIZATION REPORT NO.
 9. PERFORMING ORGANIZATION NAME AND ADDRESS
   University of Florida
   Agricultural Engineering  Department
   Gainesville, Florida   32611
             10. PROGRAM ELEMENT NO.
                 1BC822
             11. CONTRACT/GRANT NO.

                   S800829
 12. SPONSORING AGENCY NAME AND ADDRESS
   Robert S. Kerr  Environmental  Research Lab-Ada, OK
   Office of Research and  Development
   U.S. Environmental Protection Agency
   Ada, Oklahoma   74820
                                                           13. TYPE OF REPORT AND PERIOD COVERED
             14. SPONSORING AGENCY CODE

                 EPA-600/15
 15. SUPPLEMENTARY NOTES
 16. ABSTRACT
   Municipal wastewater  from  the City of Tallahassee,  Florida,  which has received
   secondary treatment was  used  to demonstrate the effectiveness of wastewater
   renovation without pollution  of groundwater or surface  water through land
   application to forage  crops  by sprinkler irrigation.  Five summer and two winter
   forage crops were grown  with  applied wastewater at  rates  up  to 200 and 100 mm per
   week, respectively.   Vegetation was harvested at appropriate stages of growth and
   evaluated for yield response, forage quality, and nutrient removal.  Groundwater
   chemical  characteristics were measured in wells located in the irrigated fields
   and compared with off-site control  wells and the applied  wastewater.  Soil samples
   were collected from several  plots  at various depths through  time to characterize
   the change in soil properties in relation to chemical processes and crop
   production.
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
                                              b.lDENTIFIERS/OPEN ENDED TERMS  C. COSATI Field/Group
   Land  use/water quality
   Sewage  treatment/winter reclamation
   Groundwater/soi1  water
   Environmental  engineering/waste  disposal
 Land treatment/sewage
  effluents
 Land pollution  abatement
 Land management/crop
  management
 Wastewater spray irrigat
                                                                         on
68D
68C
48B
48G
48E
91A
 3. DISTRIBUTION STATEMENT
     RELEASE  TO PUBLIC
                                              19. SECURITY CLASS (This Report)
                                                  UNCLASSIFIED
                           21. NO. OF PAGES
                                340
20. SECURITY CLASS (This page)
    UNCLASSIFIED
                           22. PRICE
EPA Form 2220-1 (9-73)
                                            320
                                                                  4 U-S. GOVERNMENT PRINTING OFFICE. 1979-657-060/5387

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