Environmental  Protection Technology  Series
Herbicide  Runoff From Fo
Coastal Plain Soil Types
                                 National Environmental Research Center
                                 Office of Research and Development
                                 U.S. Environmental Protection Agency
                                 Corvallis, Oregon 97330

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Research reports of the  Office  of  Research  and
Monitoring,  Environmental Protection Agency, have
been grouped into five series.  These  five  broad
categories  were established to facilitate further
development  and  application   of   environmental
technology.   Elimination  of traditional grouping
was  consciously  planned  to  foster   technology
transfer   and  a  niaximuai  interface  in  related
fields.  The five series are:

   1«  Environmental Health Effects Research
   2.  Environmental Protection Technology
   3.  Ecological Research
   4.  Environmental Monitoring
   5.  Socioeconomic Environmental studies

This report has been assigned to the ENVIRONMENTAL
PROTECTION   TECHNOLOGY   series.    This   series
describes   research   performed  to  develop  and
demonstrate   instrumentation,    equipment    and
methodology  to  repair  or  prevent environmental
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.

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                                                   EPA-660/2-74-017
                                                   April 1974
                   HERBICIDE RUNOFF FROM FOUR

                    COASTAL PLAIN SOIL TYPES
                               by

                           G.W. Bailey^
                         A.P.  Barnett
                        W.R.  Payne, Jr.
                           C.N. Smith
          Southeast Environmental Research Laboratory
                      College  Station Road
                     Athens, Georgia  30601
                               and

                                                       2
       Southern Piedmont Conservation Research Center
                Soil, Water and  Air Sciences
                       Southern  Region
                          ARS, USDA
                Watkinsville,  Georgia  30677
                     Program Element 1BB039
             NATIONAL ENVIRONMENTAL RESEARCH CENTER
               OFFICE OF RESEARCH AND MONITORING
              U.S. ENVIRONMENTAL  PROTECTION AGENCY
                    CORVALLIS,  OREGON  97330
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.45

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                                ABSTRACT

    The movement of two herbicides in runoff and on sediment were
studied as examples of pesticides in general use.  Gas chromatography
was used to determine the losses of atrazine (2-chloro-4-ethylamino-6-
isopropylamino-s-triazine) and dichlobenil  (2,6-dichlorobenzonitrile
from fallow plots on four Coastal Plain soil types following the
application of about 13 cm  (5 in.) of rainfall in 2 hours.
    The herbicides, as wettable powders, were surface-applied and
incorporated.  Simulated high intensity  (a  100-year frequency storm)
rainfall was started 1 hour after application.
    Significant amounts of both compounds were transported.  The percent
loss was greater in all cases for atrazine, but because more dichlobenil
was applied, its losses were greater on an  absolute basis.  Some of the
herbicide in the sediment may have been transported as discrete particles
rather than as an adsorbate.
    The greatest combined  (runoff plus sediment) losses of atrazine in
all soils and of dichlobenil in two soils occurred during the first
40-50 minutes of runoff.  During this time, the absolute amount of both
herbicides was greater in runoff, but the concentrations were greater in
the sediment.  The preferential loss of certain clay-sized materials
during the first 50 minutes of runoff may explain the high herbicide
concentration in sediment relative to later times.
    Over the entire event,  70-80% of the total herbicide loss occurred
in the runoff.
                                    ii

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                              CONTENTS




                                                          Page




Abstract                                                   ii




List of Figures                                            iv




List of Tables                                             vi




Acknowledgments                                            vii






Sections




I      Conclusions                                          1




II     Recommendations                                      2




III    Introduction                                         4




IV     Experimental Methods                                 6




V      Results and Discussion                              16




VI     References                                          62




VII    Glossary                                            65




VIII   Appendices                                          66
                                 iii

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                                FIGURES

No.                                                                Page

 1   Sediment and water losses by time periods on Dothan, Site 2    19

 2   Sediment and water losses by time periods on Red Bay, Site 5   20

 3   Sediment and water losses by time periods on Malbis  (Bowie),   21
     Site 6

 4   Sediment and water losses by time periods on Malbis  (Bowie),   22
     Site 7

 5   Particle size distribution in runoff from Dothan sandy loam    23
     ^average of 3 sites)

 6   Particle size distribution in runoff and surface soil of Red   24
     Bay sandy loam (average of 3 sites)

 7   Particle size distribution in runoff and surface soil of       25
     Malbis (Bowie) sandy loam (average of 2 sites)

 8   Herbicide losses in runoff and on sediment from Dothan,        28
     Site 2, (A) atrazine, (B) dichlobenil

 9   Atrazine losses in runoff and on sediment from Red Bay,        29
     Site 5

10   Dichlobenil losses in runoff and on sediment from Red Bay,     30
     Site 5

11   Atrazine losses in runoff and on sediment from Malbis          31
     (Bowie), Site 6

12   Dichlobenil losses in runoff and on sediment from Malbis       32
     (Bowie), Site 6

13   Herbicide losses in runoff and on sediment from Malbis         33
     (Bowie), Site 7, (A) atrazine, (B) dichlobenil

14   Cumulative total herbicide loss in runoff and on sediment      43
     from Dothan, Site 2

15   Cumulative total herbicide loss in runoff and on sediment      44
     from Red Bay, Site 5
                                    iv

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                           FIGURES (Continued)

No.                                                                Page

16   Cumulative total herbicide loss in runoff and on sediment      45
     from Malbis  (Bowie), Site 6"

17   Cumulative total herbicide loss in runoff and on sediment      46
     from Malbis  (Bowie), Site 7

18   Cumulative loss of atrazine on sediment                        47

19   Cumulative loss of dichlobenil on sediment                     48

20   Cumulative herbicide loss in runoff and on sediment from       49
     Dothan, Site 2

21   Cumulative herbicide loss in runoff and on sediment from       50
     Red Bay*  Site 5

22   Cumulative herbicide loss in runoff and on sediment from       51
     Malbis  (Bowie), Site 6

23   Cumulative herbicide loss in runoff and on sediment from       52
     Malbis  (Bowie), Site 7

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                                   TABLES

No.                                                                Page

 1   Herbicide properties                                            8

 2   Herbicide loss and the accompanying rainfall, runoff, soil     10
     loss, herbicide application rate, and temperature

 3   Physicochemical properties of experimental sites               17

 4   Moisture content profile                                       27

 5   Herbicide concentration (ppm) in runoff and on sediment        34
     from Dothan, Site 2

 6   Herbicide concentration (ppm) in runoff and on sediment        35
     from Red Bay, Site 5

 7   Herbicide concentration (ppm) in runoff and on sediment        36
     from Malbis (Bowie), Site 6

 8   Herbicide concentration (ppm) in runoff and on sediment        37
     from Malbis (Bowie), Site 7

 9   Percent cumulative and fractional loss of herbicides on        56
     Dothan, Site 2

10   Percent cumulative and fractional loss of herbicides on        57
     Red Bay, Site 5

11   Percent cumulative and fractional loss of herbicides on        58
     Malbis (Bowie), Site 6

12   Percent cumulative and fractional loss of herbicides on        59
     Malbis (Bowie), Site 7
                                    vi

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                             ACKNOWLEDGEMENTS

     The authors are grateful to the following people for their assist-
ance:
     A. Burks, K. S. Buxton, and J.E. Benner, Southeast Environmental
Research Laboratory, NERC, Corvallis, EPA, and A.E. Dooley and G.A.
Smith, Southern Piedmont Conservation Research Center, ARS, USDA for
their technical assistance in carrying out this study;
     Lewis Williams, Conservation Agronomist, and Carter Steers, State
Soils Correlator, Soil Conservation Service, Auburn, Alabama, for pro-
viding a list of suitable test sites and for information on soil
classification and rainfall characteristics;
     C.A. Brogden, Station Superintendent, Jim Starling, Assistant
Superintendent, Henry Ivey of the Wiregrass Experiment Station, Headland,
Alabama, and Harold Yates, Station Superintendent, Gulfcoast Experiment
Station, Fairhope, Alabama, for assistance in supplying comprehensive
information on plot history, for providing test sites for the study,
and  for providing necessary facilities for laboratory space and mobile
trailer installation for the duration of the study;
     Dr. A.R. Hiltbold, Department of Soils, Auburn University, for
information on herbicide persistence work at Wiregrass Experiment
Station;
     C.P. Bianco, District Conservationist, SCS, Foley, Alabama, for
providing general background information of soils and climatology of the
Gulfcoast Station;
     To Drs. John E. Eisner and Joel Giddens, Agronomy Department,
University of Georgia, for loan of the pesticide applicator;
     Drs. James F. Miller and Charles W. Swann, Extension Agronomists
and  Weed Control Specialists, University of Georgia, for help on problems
associated with herbicide application formulation  and application rates.
     Dr. W.C. Steen for his critical review of the manuscript, Dr. R.R.
Swank, Jr., for his many helpful discussions, and Mrs. Shirley Hercules
                                    vii

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for her technical editing assistance;  and
     Dr. R.P. Nicholson, Chief, Agro-Environmental Systems Branch,
Southeast Environmental Research Laboratory, for his administrative
support, technical assistance, and encouragement during the planning
and implementation of the field study and the preparation of the final
report.
                                   viii

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                               SECTION I
                              CONCLUSIONS

1.  Runoff was the major transport mode for atrazine and dichlobenil
    (weakly basic, nitrogen-containing, chlorinated, aromatic herbicides)
    from sandy Coastal Plain soils under simulated high intensity rain-
    fall.  Although the herbicide concentration was greater in the
    sediment phase, the absolute amount of both herbicides was greater
    in runoff.
2.  The combined, i.e., runoff plus sediment, losses of atrazine and
    dichlobenil were greatest during the first 40-50 minutes of runoff.
3.  Such factors as pesticide type, soil type, rate and mode of applica-
    tion, and formulation properties influence the extent and distribu-
    tion of pesticide transport from fallowed soil under simulated high
    intensity rainfall.
4.  Field gas chromatographic analysis of extracts is a feasible
    procedure.  However, best productivity would be attained were the
    samples separated, extracted, concentrated, and then sent to the
    home laboratory for analysis.

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                               SECTION II
                             RECOMMENDATIONS

1.   The following procedures are recommended to make future studies
    more fruitful.
    A.   To assess the degree of pesticide downward movement, soil
        samples should be collected at 0.7 cm (0.3 in.),  7.5-15 cm
        (3-6 in.), and 15-30 cm (6-12 in.) depths (1) prior to pesticide
        application,  (2)  immediately after pesticide application and
        prior to starting the rainfall,  and (3) at the end of the runoff
        event.
    B.   To assess volatility losses, soil surface temperature should be
        measured (1)  prior to pesticide application, (2)  immediately
        after pesticide application, (3) at 0,  30, 60, 90, and 120
        minutes after runoff has started, and (4) after runoff has
        stopped.
    C.   To assess the possible occurrence of pesticide vapor loss during
        runoff, temperature measurement of runoff should be taken at
        0, 30,  60, 90, and 120 minutes after initiation of rainfall and
        at the end of runoff.
    D.   To correlate  pesticide losses with physical processes occurring
        during runoff and erosion,  a sequence of colored slides viewing
        the plot at various intervals should be taken (1) during soil
        preparation,  (2)  prior to pesticide application,  (3) immediately
        after pesticide application, (4) at 0,  30, 60, 90, and 120
        minutes after initiation of runoff, and  (5) after runoff has
        stopped.
    E.   To determine  pesticide persistence, soil samples should be
        collected at  0.5, 1, 2, 3,  6, and 12 months after initial tests
        are complete.
2.   Because the distances involved in the study gave rise to serious
    logistical problems,  future field studies should be conducted closer

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    to the home laboratory or provisions made for quick shipment of
    samples, e.g., charter aircraft or express busses could be used.
3.  A computer program should be written to calculate differential and
    integral sediment, runoff, and pesticide (in both runoff and sediment)
    losses.

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                              SECTION III
                             INTRODUCTION

     The use of pesticides in American agriculture has increased
production efficiency, a benefit passed on to the consumer in the form
of a lower cost for food and clothing than would otherwise be possible.
     However, chemical control of agricultural pests may also create
problems.  Some pesticides applied to crops and soils do not remain on
site, but through rainfall and erosion are carried into receiving waters
in various ways—dissolved in the runoff, adsorbed on eroded soil
particles, or transported as particulates.  (Nicholson et al., 1962;
Grzenda et al. 1964; Nicholson et al., 1964; Lauer et al., 1966;
Nicholson et al., 1966; Barnett et al., 1967; White et al., 1967;
Hall et al., 1972.)  The environmental hazard created by such pollution
has stimulated considerable research in the area of agricultural runoff.
     Managerial and engineering techniques must be developed to prevent
or control the pollution hazards resulting from agricultural runoff.
The formulation of such techniques, however, requires an understanding
of the influence on pollution potential of the following factors:  soil
properties, rainfall characteristics, pesticide type and formulation,
agricultural practices, watershed characteristics, and pesticide
attenuation processes.  To this end, studies have been conducted on
small well-characterized plots to which pesticide is applied in various
specified manners.
     The use of natural rainfall in runoff studies is very inefficient,
since one cannot control the frequency, the intensity, and the duration
of rain.  Simulated rainfall, an important tool in erosion studies for
over a decade (Meyer, 1965), has been shown to be of use in studying
pesticide runoff from agricultural land (Barnett et al., 1967 and White
et al., 1967).
     A cooperative study between the Agro-Environmental Systems Branch,

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SERL, NERC, Corvallis, EPA, and Southern Piedmont Conservation Research
Center, ARS, USDA, was undertaken in the summer of 1970 because of a
joint interest in the area of herbicide runoff.  The objectives of the
investigation were (1) to study the effect of soil type, pesticide type,
and application rate of the amount and distribution of pesticide in
runoff; (2) to evaluate field procedures for conducting future such
studies; and  (3) to evaluate the usefulness of the rainfall simulator in
pesticide runoff studies and future modeling efforts.

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                               SECTION IV
                          EXPERIMENTAL METHODS

FIELD PROCEDURES

Site Selection
     The selection of four sites for the runoff study was based on
(1) soil type, (2) slope of plot, (3) cropping and pesticide usage
history, (4) future use of plot, and (5) effects of drainage on contig-
uous areas.
     Surface samples were taken for analytical reference blanks from the
prospective sites to determine herbicide background levels.  Detailed
information concerning the morphological character, physicochemical
properties, and genesis of the four soil types is found in Appendix B.
     One site (Site 2) located at Wiregrass Experiment Station, Headland,
Alabama, was a Dothan sandy loam on a 2.2% slope near a "grady pond" (a
pond typical of southern Alabama, that fills with water in the winter
and dries out in the summer).   Three sites were located at Gulfcoast
Experiment Station, Fairhope,  Alabama:  Site 5, Red Bay sandy loam, 2.5%
slope;  Site 6, Malbis (Bowie)  sandy clay loam, 3.6% slope; and Site 7,
Malbis  (Bowie) sandy loam, 5.7% slope.   All sites were cropped to
soybeans or corn.  Site numbers were assigned in connection with a
companion study and are therefore not consecutive.

Site Preparation
     The major portion of foliage was removed from the soil surface by
hand prior to tillage.  Each site was divided into two plots, 1.83 m x
10.66 m (6 ft x 35 ft), separated by a 0.31 m (12 in.) walkway.  One
plot was used for the pesticide runoff experiment, the other for soil
erodibility determination.  Border material was placed to outline  the
experimental plots and the rainfall simulator was set up over the  area.

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The soil was fallowed with a rotary tiller and raked smooth to reduce
surface irregularities and to remove any remaining plant residue.  A
control site, 1.83 m x 1.83 m (6 ft x 6 ft) was prepared in a similar
manner near each of the test sites.  For Site 2, one of the plots into
which the site was divided was used a a suplicate plot.  Pretreatment
samples were taken of soil from each plot.

Pesticide Application
     Atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine;
Aatrex  ) and dichlobenil  (2.6-dichlorobenzonitrile; Casoron  ) were
selected as the test herbicides since background information was avail-
able on them from previous in-house research.  Some properties of these
two herbicides are given in Table 1.
     Dichlobenil (DCBN) was applied at the recommended rate, 6.72 kg/ha
active ingredient  (6.0 Ib/A), as a 50% wettable powder formulation to
all four plots.  Atrazine was applied at the recommended rate, 3.36
kg/ha active ingredient  (3.0 Ib/A) to Site 5 and Site 7 as an 80%
wettable powder and at the rate of 1.68 kg/ha (1.5 Ib/A) to Site 2 and
Site 6.  The two herbicides were applied simultaneously to both test
and control plots 1 hour before the test storm in a volume of 590 1/ha
(60 gal./A) with a precalibrated conventional CO,, powered bi-wheeled
applicator.  This type of applicator had several advantages over a
3-gallon tank sprayer in that it could (1) apply test herbicides more
uniformly over the area treated, (2) provide sufficient agitation for
uniform mixing, and  (3) more accurately apply predetermined dosages.
     The herbicides were immediately incorporated to a depth of about
3 in., by harrowing parallel to the slope with a drag harrow to provide
plot surfaces of uniform configuration and reproducibility.
     To ensure that compound carry-over from plot to plot did not occur,
gas chromatographic analyses were performed on samples of the water used
to wash the sprayer.

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                                              Table  1.   HERBICIDE  PROPERTIES
        Cbmpound
Structural Formula
Properties
 Application Rate of
  Active Ingredient
Common name: atrazine
  2-chloro-4-(ethylamino)
  -6-(isopropylamino)
  -s-triazine
Trade name:  Aatrex SOW
Formulation:
  80% wettable powder
                              CH,
                              CH
                                 )>CHNH-c
Molecular formula:
Molecular weight: 215.7
Physical state and color:
  White, crystalline solid
Melting point: 173° to 175°C
Vapor pressure:
  Temperature °C
       10
       20
       30
       50
                                                  mm Hg
                                                 5.7 x 1
                                                 3.0 x 1
                                                                                  1.4 x 10
                                                 2.3 x 10
                              Water solubility at 27°C:
                                33 ppm
                    -8
                    -7
                    -6
                    -5
                                                                  2.24-4.48 kg/ha (2-4 Ib/A)
Geigy Agricultural Chemicals
Research and Development
Saw Mill River Road
Ardsley, New York 10702
Common name:  dichlobenil

  2,6-dichlorobenzonitrile

Trade name:  Casoron W-50
 Formulation:
   50% wettable  powder
                             Molecular formula:  C-^HoC^N
                             Molecular weight:  172.0
                             Physical state, color:
                               White, crystalline solid
                             Melting point: 145° to 146°C
                             Vapor pressure:
                                                                Temperature
                                                                    20
                                                                    50
                                                                    100
                                                  mm Hg   -
                                                 5.5 x 10"
                                                 1.5 x 10"f
                                                 1.1 x 10"1
                             Water solubility at 20 C:
                                18 ppm
                             4.48-6.72 kg/ha (4-6 Ib/A)
                             Thompson-Hayward Chemical
                               Co.
                             P. 0. Box 768
                             Kansas City, Missouri  64141

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Rainfall Simulator
     A rainfall simulator, "rainulator," described by Meyer and McCune
(1958) and modified by Cobb et al.  (1961), was used to provide erosional
energy.  Water for the simulator was obtained from local municipal water
systems and stored in a tanker truck.  Gas chromatographic analysis of
the water was negative for both herbicides.  The temperature of the
"rainwater" and the washoff were measured  (Table 2).
     The rainfall amount was calculated by measuring the water collected
on two U-shaped troughs placed diagonally across the plot.  Rainfall at
an intensity of 6.35 cm/hr (2.5 in./hr) with a storm duration of 2 hours
was applied to the test sites only, beginning 1 hour after herbicide
application.  The simulated rainfall was comparable to a "100-year
frequency storm" in the Alabama Coastal Plain Region, i.e., a storm that
would occur once every 100 years, on the average (Hershfield, 1961).
     Photographs illustrating the operation of the rainfall simulator are
found in Appendix A.

Sampling Procedures
     Sediment and runoff samples were collected in 1-quart containers
from a runoff trough at the base of the plots at the beginning of runoff,
then every 2 minutes for 10 minutes, every 3 minutes for 15 minutes,
every 5 minutes for 25 minutes, and finally every 10 minutes until the
end of runoff.  All samples were sealed with a stopper, covered with
aluminum foil, and refrigerated immediately after the run.  Samples from
Site 2 were iced down and transported to Fairhope.
     Flow measurements to determine the runoff hydrograph, a plot of run-
off rate versus time, were made at various time intervals during the runoff
event by recording the length of time, to the nearest 0.1 sec, required to
fill containers of known volume.  Measurements were made using 1-qt and
1- and 2- gallon containers.  As filling time for each smaller container

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Table 2.  HERBICIDE LOSS AND THE ACCOMPANYING RAINFALL, RUNOFF
          SOIL LOSS, HERBICIDE APPLICATION RATE, AND TEMPERATURE.
Application
Site
No.
Rate,
Formulation,
and Active
Atrazine DCBN
Dothan
Site 2

Malbis
Site 7

Malbis
Site 6

Red Bay
Site 5

2.10b
1.68C

4.20b
3.36C

2.10b
1.68Q

4.20b
3.36C

a Silt and Clay
13
6

13
6

13
6

13
6

Only
.5b
.72C

.5b
.72°

.5b
.72°

b
.72°


Herbicide Loss, Sediment, Water and
Amount Lost
kg/ha
Atrazine
Sed.
Water
Total
Sed.
Water
Total
Sed.
Water
Total
Sed.
Water
Total

0.03
0.07
0.10
0.10
0.23
0.33
0.04
0.16
0.20
0.06
0.36
0.42

DCBN
0.02
0.16
0.18
0.17
0.14
0.31
0.20
0.40
0.60
0.16
0.53
0.69

Loss, %
Total
Total Total Total
Water Water Sediment
Applied Loss Loss,a


o
Temp. , C
Atrazine DCBN cm cm kg/haXlO'1
Sed.
Water
Total
Sed.
Water
Total
Sed.
Water
Total
Sed.
Water
Total

1.95
4.49
6.44
3.04
7.14
10.2
2.17
10.3
12.5
1.90
11.4
13.3

0.36
2.36 13.4 8.50 34.8
2.72
2.55
2.07 13.5 9.40 153
4.62
2.97
5.99 13.9 10.20 154
8.96
2.33
7.61 14.6 10.50 89.4
9.94

Air
Water
Runoff
Air
Water
Runoff
Air
Water
Runoff
Air
Water
Runoff

30.0
30.9
	
32.2
28.6
32.8
....
28.6
30.6
27.5
27.2
28.1

b Formulation
c Active
Ingredient
                           10

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approached 10 sec ,  the next largest container was used to ensure
adequate accuracy at higher runoff rates.
     Soil core samples were taken for moisture and herbicide residue
determination before the event and after rainfall and runoff had ceased.
The core samples were taken at depths of 0 to 7.52 cm (0-3 in.), 7.52 to
15 cm (3-6 in.), 15 to 23 cm (6-9 in.), and 23 to 30 cm (9-12 in.).  The
moisture content was determined by oven-drying at 110°C.

LABORATORY PROCEDURES
     Although analytical methods are available for the singular deter-
mination of atrazine (Benfield and Chilwell, 1964; Sheets and Kearney,
1964; and McClamery et al., 1967) and dichlobenil (Miller et al., 1966;
Van Valin, 1966; and Briggs and Dawson, 1970), the extractions described
were found to be inefficient in samples spiked with the formulated
compound rather than the analytical grade material.  An integrated
method was therefore developed to permit simultaneous extraction and gas
chromatographic analysis of the two admixed formulated grade herbicides
from both the sediment and water fractions.

Apparatus and Reagents
     (1) Gas chromatograph - A Packard Model 7620 Gas Chromatograph
(Packard Instrument Company, Downers Grove, 111.) equipped with dual
Radium "D" (50 microcuries) electron capture detectors and dual 150-cm
(5 ft) coiled glass columns (0.4 cm i.d.) packed with 10% DC-200 on 80-
90 mesh Gas Chrom Q (Applied Science Labs, State College, Pa.).  Injec-
tion port 230°C; column temperature 190°C for atrazine, 160°C for
dichlobenil; detector temperature 220°C; nitrogen carrier gas flow 60-
90 ml/min; (2) International Centrifuges, Model K - size 2; 4 place
aluminum heads for 600-ml bottles; (3) Solvents - Burdick and Jackson
pesticide grade chloroform, methylene chloride, acetone, and benzene;
(4) Reagents - Sodium chloride and sodium sulfate anhydrous, A.C.S.
                                      TM
Certified; and (5) Herbicides - Aatrex   SOW (76% atrazine), CIBA-Geigy
                                    11

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                         TM
Chemical Company; Casoron   50-W (50% dichlobenil),  Thompson-Hayward
Chemical Co.
Sediment-Water Separation
     Refrigerated runoff samples were brought to room temperature and
stirred, first vigorously to disperse the clay and silt and then slowly,
to permit the sand fraction to settle to the bottom.  While the suspen-
sion was still in motion, a 10 ml aliquot was removed for determination
of the clay-silt content by drying and weighing.  In all further
discussion, the term "sediment" will refer only to the clay and silt
fraction unless otherwise stated.
     The suspension was drawn off into two 500 ml centrifuge bottles,
filling one and partially filling the other.  Following the addition of
about 15 g of NaCl to each bottle, the clay-silt-sized particles were
sedimented out by centrifuging at 2200 RPM for 10 minutes.  The super-
natants were decanted and combined.
     The sediment from one centrifuge bottle was transferred into a
small bottle containing 5 ml chloroform.  The lid was lined with
aluminum foil and sealed on the bottle with plastic tape.  The sample
was then frozen and sent to the Southeast Environmental Research Labor-
atory for analysis.  The sediment from the second of the centrifuge
bottles was analyzed on site.  Comparison of the results from the frozen
sediment with those obtained at Gulfcoast on the unfrozen samples
indicated that volatilization and degradation of the residue during the
freezing and transport steps were negligible.

Extraction and Analysis
     The sediment was extracted for 4 hours in a Soxhlet apparatus with
acetone.  The extracting solution was concentrated to 100 ml and diluted
to about 900 ml with distilled water.  Further extraction of the result-
ing solution was performed with one 100-ml and three 50-ml portions of
chloroform.  The chloroform extracts were combined and passed through a

                                    12

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sodium sulfate column to remove traces of water.  The chloroform was
evaporated and the residue taken up in benzene for gas chromatographic
analysis.  A similar procedure was performed on the frozen sediment.
     The supernatant was extracted with methylene chloride (one 100-ml
and three 50-ml portions).  The combined extracting solution was
evaporated in a Kuderna-Danish apparatus and the residue taken up in
benzene for gas chromatographic analysis.
     Aliquots of the benzene-herbicide solutions were injected into the
gas chromatograph onto the column previously described.  The identifi-
cation and quantitative determination of the herbicide were accomplished
by comparison of retention times and peak heights with those of stand-
ards.  The results reported are averages of the field and laboratory
analyses.
     The efficiency of the extraction technique was tested with water
spiked with the herbicide formulations.  The recovery levels of atrazine
and dichlobenil from concentrations of 0.5 ppm were 99% and 80%,
respectively.  Corrections, however, were not made to the measured data.
     Particle-size analysis of the soil from each plot and the eroded
soil was done by the conventional hydrometer method (Day, 1965).

CALCULATIONS
     Calculations of the runoff parameters were based on the following
data:  (1) the volume rate of runoff measured at specific times during
the event, (2) measured weights of sediment for each 1-quart runoff
sample taken at specified times during the event, and (3) atrazine and
dichlobenil concentrations as measured on each sample by gas chromatog-
raphy.
     Manual integration of runoff data compared favorably with inte-
grations done by computer.
1.  Runoff Rate Data - The runoff rate data (in units of volume/time as
measured by the time required to fill a container of known volume) were
converted, by using the plot size, into units of inches of runoff (or

                                    13

-------
centimeters)/time to facilitate comparison with, runoff data on any plot.
The data were compiled on a computer.  Volume rates were used in further
calculations.
2.  Runoff Volume - Manual interpolations were performed between data
points to determine the average runoff rate at each minute in inches (or
centimeters)/minute during the runoff event.  Integrations of the
resulting runoff rate data were performed over the entire event and over
selected time periods to obtain runoff volume over the desired time
period.

  minute y
    •c-—      inches runoff       .           ,        _.      .       ..
    >        	:	   x  time  =  inches runoff over interval
    *•—          time                              .,   v
  minute x                                         ('y~x'

3.  Sediment Delivery Rate - The sediment delivery rate was determined
for each sampling time by using the total sediment weight for the sample,
the liquid volume of the sample, and the volume rate of runoff at that
time.

  sediment weight     runoff volume   _   sediment weight
  sample volume           time                  time

4.  Sediment Weight - Interpolations and integrations analogous to
those performed on water runoff data yielded the weight of soil eroded
in pounds (or kilograms)/minute over the calculated intervals.

  minute y
               ,.        .  .                 sediment
    v—      sediment weight       .          .  ,   .
    >	      	—	"—   x  time  =  weight lost
     —           time                          •       -i  /   \
  minute x                                 over interval (y~x)

5.  Herbicide Runoff Rates and Weights - The rate of herbicide runoff
as a function of time in runoff water and sediment was calculated in a
manner similar to that used for sediment rate calculations.
                                    14

-------
                   	herbicide weight in sample	
                   sample volume (or sediment weight)

         runoff volume (or sediment weight)      herbicide weight
                     time                             time

     Interpolation and integration of the resulting data provided total
weight data for herbicides over intervals calculated.

  minute y                                           . . ,    .
              ,   ,  .  . ,     . ,          .         herbicide weight loss
    X—       herbicide weight   x.   time   =        .       -, /   \
    >         	T	c—                  over interval (y-x)
     	            time
  minute x

6.  Pesticide Concentration Data - The concentration of herbicide in
either water or sediment at any given time was calculated by using the
calculated rate of herbicide loss at that time and the corresponding
volume rate of water runoff (or weight rate of sediment loss).

  herbicide weight   •  runoff volume (or sediment weight)  _
       time          •              time

                          herbicide weight	
                 runoff volume  (or sediment weight)

7.  Percent Herbicide Loss - The fractional loss of herbicide was
based on the total amount lost  over a given period  (or over the whole
event).
                                   15

-------
                               SECTION V
                         RESULTS AND DISCUSSION

     Extensive research on the problem of runoff and soil erosion has
shown it to be a complex phenomenon.  Runoff is affected by such factors
as rainfall characteristics (i.e., amount, duration, intensity, and
frequency), antecedent soil moisture, watershed characteristics (i.e.,
area, shape, slope orientation, type of drainage, net extent of induced
drainage, and presence of artificial drainage), and cultural and
managerial practices.  Soil loss is affected by rainfall, soil credi-
bility, slope length and gradient, crop management, and erosion control
practices (Wischmeier and Smith, 1965).  Pesticide attenuation behavior
and persistence have been shown over the last decade to be governed by
a combination of factors, such as adsorption-desorption, volatilization,
organism uptake, vertical movement, and chemical, photochemical, and
microbial degradation.  The study of pesticide transport and movement
from agricultural land is therefore a complex problem.

PROPERTIES OF SOILS IN RUNOFF STUDY
     Physicochemical properties of the four soils studied are given in
Table 3.  All four soils are coarse-textured, moderately to well drained,
highly acidic, moderately permeable, and relatively low in organic
matter.  They occur on gently sloping landscapes and are derived from
unconsolidated marine sediments.  Detailed morphological characteristics
and genesis information are found in Apprendix B.
     The soil credibility factor, K, a part of the Universal Soil Loss
Equation developed by USDA (Wischemeier and Smith, 1965), is a measure
of the relative ease with which a soil will erode under standard
conditions of 9 percent slope and 72.6 ft slope length.  For a given
set of rainfall, topographic, and management conditions, K is proportion-
al to the degree of erosion.   The studied soils in order of increasing K
are Site 2, Site 5, Site 7, and Site 6 (Table 3).
                                   16

-------
Table 3.  PHYSICOCHEMICAL PROPERTIES OF EXPERIMENTAL SITES


Experimental
Site
Wiregrass


Gulfcoast


Gulfcoast




Gulfcoast





Run
No.
1


4


3




2





Site
No.
2


5


6




7





Slope,
aj
2.2


2.5


3.6




5.7





Soil
Type
Dothan
Sandy
Loam
Red Bay
Sandy
Loam
Malbis
(Bowie)
Sandy
Clay
Loam
Malbis
(Bowie)
Sandy
Loam

Particle Size
Distribution, %
Sand Silt Clay
79.9


65.9


53.9




71.3



4.3


18.1


25.7




16.0



15.3


16.0


20.4




12.7





Organic
Matter^
0.80


1.45


1.60




2.55





Soil
PH
5.2


5.4


5.6




5.6



Soil
Erodi-
bility
Factor K
0.26


0.35


0.60




0.56




-------
SEDIMENT AND WATER LOSS
     Sediment and water losses by time periods for each of the four soils
are shown in Figures 1-4.  Runoff rates, lowest during the early stages
of rainfall, increased as a function of time, and stabilized about 20 minutes
after the onset of rainfall.   With the exception of Site 7, soil loss was
greatest at the early stages  of the runoff event and then decreased to a
relatively constant value.
     The sediment loss reported in Table 2, as explained previously,
reflects only the combined clay and silt-size fractions; the total soil
loss (i.e., sand, silt, and clay fractions) was generally greater by
about a factor of two.  The greatest overall sediment loss (sand, silt,
and clay) occurred from the two Malbis soils, i.e., Sites 6 and 7 (15,270
and 15,400 kg/ha or 6.81 and  6.87 T/A); the Red Bay and Dothan soils lost
significantly less at 940 kg/ha (3.99 T/A) and 3,480 kg/ha (1.56 T/A).
     The particle size distribution of the sediment differed from that
of the surface soil and varied with time during the runoff event (Figures
5-7).  For all soils, the sand concentration increased and silt concen-
tration decreased from onset  of runoff; the concentration of clay was at
its maximum near the onset of runoff and decreased to a relatively
constant value by approximately 40 minutes after onset of rainfall.   The
leveling value for clay content of the total (including sand) sediment
was about 40% for each of the two Malbis soils.
     The fraction of the applied rainfall that appeared as runoff was
less for the Dothan soil (63%) than for the other three soil types
(Malbis, Site 7, 70%; Malbis, Site 6, 72%; and Red Bay, Site 5, 74%).  A
high infiltration rate, presumably due to the coarser texture of the
soil, is proposed as an explanation.  The soil with the greatest slope
(Malbis, Site 7) would be expected to give rise to the maximum soil loss
and runoff.  However, the higher organic content and resulting higher
infiltration rate apparently  were sufficient to counteract the effect of
the slope, giving Site 7 the  second lowest runoff rate.
                                    18

-------
.ov

.50
E
o
. .40
CO
CO
o
3 .30
ac
P 20
5
.10
nn
• SEDIMENT
D WATER
-
r

-



-

-

RUNOFF 	
STARTED |














.1






J







1















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r






1
r






,i







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.1








i









.1









.1









.1









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.,










,1


-



-

	 RAINFALL
STOPPED

RUNOFF
TENDED
n , !
I.CV
CO
i.oo 2
r~
r
.80 0
CO
CO
«•
.60 *r
x^
.40 g"
tt
.20 0
c>
on
      20  30  40  50 60 70  80  90  100 110  120  123
        TIME-MINUTES  FROM ONSET OF RAINFALL
Figure 1.   SEDIMENT AND WATER LOSSES BY TIME PERIODS ON DOTHAN, SITE 2.

-------
.60
    .50

E
o
 -   .40
CO
CO

3  .30

a:

H  .20


?

    .10
.00

-
-
-
-

RUNOFF -i
STARTED 1




-

i


rl



1






. J_ J


n



. J.













j_






1






. j_






1






1

1 r






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-













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1







• SEDIMENT
HI WATER
-
-
RAINFALL
STOPPED
RUNOFF .
TENDED
^n . !
I.ZU
1.00
.80
.60
.40

.20
r»n
                                                                           O

                                                                           CO

                                                                           CO
                                                                           a

                                                                           x


                                                                           O

                                                                            GJ
           6 10 20  30  40  50  60  70  80 90  100  110 120  124


                TIME-MINUTES FROM ONSET OF  RAINFALL
          Figure 2.  SEDIMENT AND WATER LOSSES BY TIME PERIODS ON RED BAY, SITE 5

-------
   .50

E
u
 .  .40
to
CO

3  .30
UJ   __
H  .20
    .10
   .00
• SEDIMENT


-
-

RUNOFF — ,
STARTED 1























1




1



















j.











































































LI WATER

-
RAINFALL
I STOPPED
RUNOFF -
ENDED
*n , !
I.ZU
(0
i.oo 2
r
.80 0
(0
CO
«
.60 *•
.40 a
X
.20 0
01
nn
              3 10  20 30  40 50  60 70  80  90  100 110  120  124


                     TIME-MINUTES FROM ONSET OF RAINFALL
          Figure 3.   SEDIMENT AND WATER LOSSES BY TIME PERIODS ON MALEIS(BOWIE),  SITE 6.

-------
(O
Ni
      E
      u
      •»
     (0
     «0
     o
.O V
.50
.40
.30
.20
.10
nn
• SEDIMENT
D WATER
-

-
RUNOFF— I
STARTED '

-
L J

•I






•I



n



-i







-I



























































•
-
RAINFALL
F STOPPED
RUNOFF .
ENDED
1
In 1 1
i.eu
1.00
.80
.60
.40
.20
no
                    6 10  20  30  40 50 60 70  80  90 100  110  120 122

                         TIME-MINUTES FROM ONSET OF  RAINFALL
O
(0
V)
                                                                                    o
                                                                                    01
              Figure 4.  SEDIMENT AND WATER LOSSES BY TIME PERIODS ON MALBIS  (BOWIE), SITE 7.

-------
s80
   60
Q.
UJ
CO

Ul
N

CO

UJ

O
    40
    20
                             SAND
                                                   <
                                                   col

                                                   SURFACE
                                                   HORIZON
       0      20    40     60     80     100

        TIME-MINUTES  FROM ONSET OF RAINFALL
Figure 5. PARTICLE SIZE DISTRIBUTION IN RUNOFF FROM DOTHAN SANDY LOAM (AVERAGE OF 3 SITES).

-------
to
    co  80
    UJ
       60
o.
UJ
co

UJ
N
CO

UJ

o
    (K
    <
    a.
       40
       20
                                                    Cfl
                                                      SURFACE

                                                      HORIZON
       0      20     40     60     80     100

        TIME-MINUTES  FROM ONSET OF RAINFALL
                 Figure 6. PARTICLE SIZE DISTRIBUTION IN RUNOFF AND SURFACE

                        SOIL OF RED BAY SANDY LOAM (AVERAGE OF 3 SITES).

-------
NJ
Ln
    co  80r
    UJ
       60
Q.
UJ
CO

UJ
N
(0

UJ
    CL
        40
        20
                               SAND
                                                            o
                                                         SURFACE
                                                         HORIZON
       0       20     40     60     80     100

        TIME-MINUTES  FROM  ONSET OF RAINFALL
               Figure 7.  PARTICLE SIZE DISTRIBUTION IN RUNOFF AND SURFACE SOIL
                       OF MALBIS (BOWIE) SANDY LOAM (AVERAGE OF 2 SITES).

-------
     The low infiltration rate and corresponding high, runoff of the Red
Bay soil relative to the Dothan may be due to the presence of a "plow
pan" (see glossary) as indicated by soil moisture data (Table 4).

HERBICIDE LOSS
     Several factors are discussed below with respect to their effect
on herbicide loss from the four sites.  Runoff data are presented in
several forms:  (1) herbicide loss per unit area as a function of time
(Figures 8-13), (2) herbicide concentration in runoff and on sediment as
a function of time (Tables 5-8), (3) total or percent herbicide lost for
each event and runoff phase (Table 2), and (4) cumulative loss, i.e.,
the fraction of the total event loss that has occurred as a function of
time.

Soil Type
     The properties of soil that influence runoff and erosion would be
expected to influence herbicide loss also.  Although direct correlations
were difficult to find, several comments may be made with respect to
herbicide loss as it relates to soil and water loss data (Table 2).
     The amount of dichlobenil lost in the sediment fraction did cor-
relate roughly with the total sediment loss for the four soils and
therefore with the soil erodibility factor.  Atrazine loss data may be
compared with soil loss data only among those soils receiving the same
application rate.  For each of the two application rates of atrazine,
only two soils were tested; therefore atrazine loss/soil loss correla-
tions are somewhat inconclusive, having been based on two points only.
Indications are, however, that herbicide loss follows soil loss for
atrazine also.
     Herbicide losses in runoff, on both an absolute and percent basis,
did correlate with water losses for both atrazine and dichlobenil.  The
deviation noted on the Malbis sandy loam, Site 7, may be caused by a
higher organic matter content, which binds the herbicide more tightly
                                   26

-------
                             Table 4.  MOISTURE CONTENT  PROFILE
                                                  Soil and Site No.
                       Dothan, #2,%
Soil Depth, cm.      Dryc
Wetc
 Red Bay, #5, %
Dry         Wet
  Malbis, #6, %
Dry        Wet
  Malbis, #7, %
Dry        Wet
0-7.6
(0-3")
7.6-15
(3-6")
15-23
(6-9")
23-30
(9-12")
6.59
8.48
12.6
13.1
19.5
18.2
15.2
15.1
6.31
7.27
8.27
10.3
17.0
9.35
8.66
10.5
10.8
13.2
15.3
17.3
19.2
17.0
16.6
17.6
9.51
11.9
12.5
13.8
22.4
15.4
12.1
13.0
 a Moisture content before application of simulated rainfall
 b Moisture content after application of simulated rainfall

-------
NJ
00
IO
1
O
- 20
x
0

1 f\
^
9
«T o
CO U
CO
0
1
20
iii fcvr
o
o
5 10

-------
VO
in ou
i
0


x 40
o>
co 30
CO
3
u, 20


o
5 10
oc
tii
X A











•
- RUNOFF -,
STARTED *









,|



• SEDIMENT
n WATER















„



n
n 	 RAINFALL
n 1" f n STOPPED
J 1 1 1 1 1 1 1 1 f] .- RUNOFF
                  6 10  20  30  40  50  60  70  80  90   100 110  120 124



                         TIME-MINUTES FROM  ONSET OF RAINFALL
         Figure 9.  ATRAZINE LOSSES IN RUNOFF AND ON SEDIMENT FROM RED BAY, SITE 5.

-------
    60
ro
2   50
    40
en
o
Ul
Q
O
0
DC
UJ
30

20

 10

  0
RUNOFF-
STARTED
I
I
]
                                                   ,
                               •  SEDIMENT
                               D  WATER
u
RAINFALL
STOPPED

 .-RUNOFF
 » ENDED
               6  10  20  30 40  50  60  70  80  90  100 110 120 124

                     TIME-MINUTES FROM  ONSET OF RAINFALL
   Figure 10.  DICHLOBENIL LOSSES IN RUNOFF AND ON SEDIMENT FROM RED BAY, SITE 5.

-------
« 60
1
o
- 50
X
0
^ 40
JC
to 30
CO
o
1
u 20


— Ift
(D
OC
I ft




• SEDIMENT
D WATER


-
-



-RUNOFF — i
STARTED |




n
RAINFALL
n STOPPED
n
J Ml 11 (1 rRUNOFF
           3 10  20  30  40  50  60  70  80  90   100  110  120 124



                 TIME-MINUTES  FROM ONSET  OF RAINFALL
Figure 11.  ATRAZINE LOSSES IN RUNOFF AND ON SEDIMENT FROM MALBIS (BOWIE), SITE 6.

-------
N3
   •o  60


    2  50
    X
       40
co   30
CO
o

    20
    £   10
111
            RUNOFF

            STARTED
              n
                                                               • SEDIMENT


                                                               D WATER
I
Ju
RAINFALL

STOPPED


  RUNOFF

  IENDED
                  3 10  20  30  40  50  60  70  80  90   100  110  120 124


                        TIME-MINUTES  FROM  ONSET OF RAINFALL
         Figure 12.  DICHLOBENIL LOSSES IN RUNOFF AND ON SEDIMENT FROM MALBIS (BOWIE), SITE 6

-------
Lo
    ,0  30
    I
    o

    - 20
     x

     o
CO
CO
o
_l

lil
g

o

CD
a:
UJ
        10
            RUNOFF

            STARTED
                     i
               w^

            Urn
                                              • SEDIMENT



                                              D WATER
J Jl JH1J I ft ll
                                                       rRAINFALL

                                                        STOPPED


                                                          rRUNOFF
                                                           J	1	L
                                                                ENDED
       20



        10
RUNOFF

STARTED
               B
Illlllllll
                                                    it
                RAINFALL

                STOPPED
                                                               r
                  RUNOFF

                  ENDED
                  6 10  20 30  40 50  60  70  80 90  100  110  120 122



                       TIME-MINUTES FROM ONSET OF RAINFALL
               Figure 13. HERBICIDE LOSSES IN RUNOFF AND ON SEDIMENT FROM

                       MALBIS (BOWIE), SITE 7,  (A) ATRAZINE, (B) DICHLOBENIL.

-------
Table 5.  HERBICIDE CONCENTRATION (ppm) IN RUNOFF WATER AND ON SEDIMENT




                          FROM DOTHAN, SITE 2
Time From
Onset of
Rainfall ,
Min
9
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
123
Sediment
Atrazine
0.0
84.6
45.8
47.4
55.6
35.7
35.1
28.0
24.6
21.0
21.5
20.0
19.5
21.5
23.8
27.5
33.3
56.0
65.1
75.5
65.2
33.0
26.4
(Runoff
DCBN
0.0
75.4
56.4
59.2
34.1
47.0
23.4
5.0
5.9
6.5
5.8
4.5
6.7
15.5
18.6
19.5
28.8
73.5
85.2
70.5
44.1
3.0
2.4
stopped)
Water
Atrazine
0.00
3.30
1.60
2.10
0.70
0.60
0.70
1.00
0.80
0.50
0.45
0.25
0.20
0.25
2.30
Negative
Negative
Negative
Negative
Negative
Negative
Negative
Negative


DCBN
0.00
4.80
2.30
2.10
2.40
1.60
1.90
1.50
1.30
1.00
0.90
0.50
0.40
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.45
0.25
0.25

                                    34

-------
Table 6.  HERBICIDE CONCENTRATION  (ppm) IN RUNOFF WATER AND ON SEDIMENT




                         FROM RED  BAY, SITE 5
Time From
Onset of
Rainfall,
Min
7
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
123
Sediment
Atrazine
0.0
137.7
33.8
24.7
20.5
25.3
44.3
44.1
44.5
44.8
45.0
44.0
42.5
42.5
42.5
39.1
38.5
29.1
22.2
8.4
5.3
5.5
5.5
5.3
(Runoff
DCBN
0.0
308.0
160.2
136.6
116.4
95.5
97.7
90.0
83.0
83.0
83.0
70.5
68.0
68.3
68.5
58.2
50.5
39.2
38.5
39.6
37.2
29.4
27.2
29.2
stopped)
Water
Atrazine
0.0
11.1
7.8
4.6
3.4
2.1
1.2
1.5
1.5
1.1
1.0
1.0
1.0
1.0
1.0
1.0
1.4
1.5
1.2
1.0
1.0
1.0
0.5
0.5


DCBN
0.0
5.2
5.3
4.0
4.0
2.8
2.3
4.2
4.0
3.7
3.5
2.3
2.0
2.3
2.5
2.5
2.2
2.0
2.0
2.0
1.6
1.5
1.1
1.0

                                    35

-------
Table 7.  HERBICIDE CONCENTRATION (ppm) IN RUNOFF WATER AND ON SEDIMENT




                     FROM MALBIS CBOWIE), SITE 6
Time From
Onset of
Rainfall,
Min
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
124
Sediment
Atrazine
0.0
58.0
17.2
15.4
11.7
11.4
4.4
1.0
1.0
1.0
1.0
1.0
1.0
5.5
7.1
9.0
8.5
14.0
15.5
16.5
15.5
25.0
28.2
18.9
(Runoff s
DCBN
0.0
389.1
113.2
86.0
62.0
56.4
26.4
8.5
9.9
41.0
46.5
58.0
55.4
55.5
57.2
57.5
56.2
49.5
48.7
48.5
49.2
48.0
47.1
34.7
stormed")
Water
Atrazine
0.0
7.9
2.0
1.4
1.0
1.0
1.0
1.0
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5


DCBN
0.0
7.6
3.4
2.7
3.0
2.6
2.2
2.0
2.0
2.0
2.5
2.5
2.0
2.0
2.0
1.5
1.4
1.5
1.6
2.0
1.5
1.0
0.9
0.5

                                   36

-------
Table 8.  HERBICIDE CONCENTRATION  (ppm)  IN RUNOFF WATER AND  ON  SEDIMENT




                     FROM MALBIS  (BOWIE), SITE  7
Time From
Onset of
Rainfall ,
Min
6
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
122

Sediment
Atrazine
0.0
67.2
42.6
18.5
19.3
19.8
22.6
17.6
18.0
51.5
59.5
64.7
56.0
13.3
13.5
18.8
20.4
24.1
23.5
25.4
26.5
45.9
49.5
53.1
(Runoff

DCBN
0.0
164.8
146.7
82.6
75.7
79.3
67.8
62.9
67.0
74.7
71.5
43.0
40.0
26.6
27.0
35.4
37.4
37.9
36.0
26.5
26.5
23.3
22.5
21.7
stopped)
37
Water
Atrazine
0.00
2.40
4.00
2.60
2.50
2.00
1.80
1.50
1.50
1.50
1.50
1.50
1.00
1.00
1.00
1.00
0.60
0.50
0.50
0.50
0.50
0.50
0.50
0.50



DCBN
0.00
2.10
3.10
1.90
1.60
1.20
1.00
1.00
0.60
0.90
1.00
1.00
1.00
0.60
0.50
0.50
0.50
0.50
0.50
Negative
Negative
Negative
Negative
Negative



-------
than the inroganic constituents.  Less herbicide can be extracted by
runoff, resulting in a lower loss.
     The lowest total (sediment plus runoff) atrazine and dichlobenil
losses occurred on the Dothan soil (Site 2) from which the soil and
water losses were lowest.
     The presence of the pan layer in the Red Bay soil (Site 5) dis-
cussed previously explains why, even though the soil loss was relatively
low, the water loss and the herbicide loss were the highest of all soils.
     For a given soil type, pesticide runoff could be decreased if (1)
infiltration and percolation rates could be increased, and (2) soil
detachability, transportability, and antecedent moisture content could
be decreased.  The latter could be done by increasing the aggregation
character of the soil, e.g., by increasing organic matter content.
Those conservation practices that decrease the intensity with which
rainfall strikes the ground (decreasing detachability) and reduce runoff
velocity (decreasing transportability) should decrease herbicide transport
in runoff and on eroded soil particles.

Herbicide Type
     The physical and chemical properties of the herbicide to a large
extent influence its runoff characteristics.  The nature of the herbicide
determines the mechanism of adsorption, the adsorption-desorption equi-
librium and kinetics, the rate of degradation and nature of degradation
products, and the rate and extent of vertical movement.  The adsorption-
desorption properties influence the distribution of the pesticide between
runoff water and sediment phases, an important factor from a toxicolog-
ical standpoint in the aquatic ecosystem.
     The proposed mechanism for bonding of the two studied herbicides to
soil are different.  Depending on the colloid type and its surface
acidity, atrazine may be bound through one or more of the following five
mechanisms:  (1) protonation and subsequent ion exchange (Russel et al. ,
1968), (2) hydrogen bonding, (3) charge transfer, (4) coordination or

                                   38

-------
chemisorption, and (5) physical adsorption  (Hayes, 1970).  Dichlobenil
has been shown by spectroscopy to be bound  to montmorillonite princi-
pally by coordination either to the exchangeable cations or to the
various spheres of ion hydration  (Payne and Bailey, 1969).  Because of
the acidic conditions found in the soils under study, atrazine should
be bound principally by protonation and subsequent ion exchange and
therefore be held more tightly than dichlobenil.  As a consequence, a
larger fraction of the applied dichlobenil  than of atrazine should have
appeared in the runoff.  However, although  a larger absolute amount of
dichlobenil was lost on all sites  except Site 7 (presumably because of
the larger application rate for dichlobenil), a larger fraction of the
applied atrazine was lost on all  sites  (dichlobenil losses range from
2.7 to 9.9%, average—6.6%; atrazine losses range from 6.4 to 13.3%,
average—10.7%).  The adsorption  characteristics, therefore, do not
appear to be dominant in determining runoff in the cases studied.
     In all cases, rainfall was started 1 hour after application.
Possibly the time allowed was insufficient  for the herbicides to reach
equilibrium with the soils.  A large portion of the herbicide in sediment
may therefore have been in either the particulate or, in the case of
dichlobenil, the vapor form instead of adsorbed on sediment (compare
vapor pressures, Table 1).  Also, the greater solubility of atrazine
(Table 1) would make it more easily extracted by the impacting raindrops
and moving water film.  Pesticide mass transfer mechanisms have been
discussed by Bailey, Swank, and Nicholson  (1973).
     In addition to pesticide solubility,  the particle size distribution
and density of the wettable powder also influence the facility of herb-
icide transport in runoff.  Since dissolution rate is roughly inversely
proportional to the square of the particle  radius, the compound with the
larger proportion of finer sized  particles  dissolves faster and is more
available for transport in runoff water.   For a given particle size, the
ease of transport as a particle in water is proportional to the runoff
velocity and inversely proportional to the  particle density.

                                   39

-------
     The greater loss of atrazine, on a percentage basis, is therefore
attributed to the following combination of factors:  (1) higher water
solubility, (2) smaller average particle size, and (3) a lower particle
density.

Other Factors
     Various other factors influence the extent of pesticide loss in
runoff and on sediment.  Because the present study was a limited one,
all such conditions could not be varied independently to draw conclusions
or correlations.
     Because the concentration of pesticide in the top layer of soil is
a crucial factor, the mode of application would affect the availability
for runoff.  Surface application gives rise to a much higher concentra-
tion for a given rate of application than does incorporation.
     As one would expect, more atrazine was lost from the sites receiving
the greater application rate.  However, since the soils were of different
types, a direct correlation could not be drawn.  For a more accurate
measure of the relationship between the application rate and pesticide
loss, varying amounts of the compound would have to be applied to the
same soil type.  In such a study, using simulated rainfall on a Cecil
soil, Barnettet al. (1967) found a positive correlation between the
concentration of 2, 4-D (2,4-dichlorophenoxyacetic acid) in runoff and
the rate of application.
     The rainfall intensity was not varied, but would be expected to
greatly influence pesticide loss.  The 100-year frequency storm simulated
in the present study is an unusually intense rainfall, but indicates the
magnitude of losses that could be expected.  Lower losses would result
from storms of shorter duration and lower intensity.
     The time lapse between application and rainfall, as indicated pre-
viously, also has a significant effect on the pesticide loss.  The
various attenuation processes, dissolution, and adsorption all alter the
availability of pesticide to runoff and erosion as a function of time.

                                  40

-------
     The extent of adsorption is influenced by temperature largely
through its effect on solubility and vapor pressure.  High temperatures
cause decreased adsorption and therefore an increase in the concentration
of pesticide available for runoff.  Soil temperatures in the present
study, from measurements of runoff temperature, were estimated to be
50-60°C, common summer surface temperatures for the area studied.
     Although its effect was not evaluated in the present study, the
cropping history does significantly influence the magnitude of runoff
and erosion.  For the same soil and rainfall characteristics, less
runoff and erosion occurs from a soil previously planted with a sod
crop than from one planted with a row crop.  The "memory" of the soil
lasts from 2 to 3 years.  Herbicide loss may be assumed to be affected
in a similar manner.

Time Distribution of Runoff
     The herbicide loss, in terms of both concentration and absolute
amount, was not distributed evenly  throughout  the rainfall event.  The
runoff events were divided into 5-minute periods, and the amount of
herbicide lost (summation of sediment and runoff loss) during each
period was caluclated as a fraction of the total event loss.  The
logarithms of the resulting figures, termed "fractional losses," were
plotted as a function of time (graphs not included).
     For the first 40 minutes after onset of rainfall, the log fractional
loss of atrazine decreased as a function of time on all soils.  The Red
Bay, Site 5, and Malbis, Site 6, had the highest initial loss.  After 40
minutes, Sites 5, 6, and 7 exhibited a constant fractional loss as a
function of time, within experimental error.  The log fractional loss
for Site 2 continued to decline until the end of the event.  No explana-
tion for this effect could be determined.
     The Dothan, Site 2, and Malbis, Site 7, log fractional loss curves
for dichlobenil were similar, showing the lowest percent of loss overall.
                                   41

-------
The higher percentage of sand in the. surface horizon of these two soils
may have provided better infiltration of water and therefore movement of
water-borne dichlobenil into the soil, giving rise to the low loss
levels.  The greater losses occurring on Sites 5 and 6 may have been due
to the greater percent of silt and clay in the surface soil and to a
plow pan in Site 5.  The resulting lower infiltration rate would give
rise to a greater runoff rate.  The silt and clay sediment fraction also
provided a "piggyback" mode of transport for the herbicides.
     The concentration of both compounds in the runoff was highest in
the early part of the test storm and decreased with storm duration,
stabilizing at a concentration of 0.5 ppm near the end.  Barnett et al.
(1967) observed the same behavior for 2,4-D in a runoff study using
artificial rainfall.
     The similarity of the total cumulative herbicide loss curves, Fig-
ures 14-17, for both herbicides and all soil types, suggests that the
rate of total herbicide loss (i.e., water plus sediment) is independent
of soil type, slope, and herbicide type.  The rainfall characteristics
may determine the rate of total loss.  Failure to obtain a straight line
for a semi-log plot of cumulative loss data versus time indicates that
the herbicide loss is not a simple exponential function.
     In cumulative loss plots (Figures 18-23), only 2 curves—dichlobenil
on Site 7 and on Site 5, both on sediment fraction—follow a smooth,
almost linear rate of increase.  Most other curves exhibit a plateau
region, a period of relatively low herbicide loss, somewhere in the
middle of the event.
     The following explanation is offered to explain the plateau formation.
From the onset of rainfall, before runoff starts, the water infiltrates
the soil forming a saturated front, which moved downward with time.  The
herbicide, whether surface applied or incorporated, moves downward with
the waterfront, moving through and out of the "zone of credibility," i.e.,
the layer of soil stripped away by erosion during the storm.  The rate
of movement of the herbicide through the soil is dependent upon its
                                    42

-------
   UJ
   o
   o

   OQ
   a:
   UJ
   I
   UJ
   >
-P-
CO
   O
       100
        80
60
        40
        20
                                                      ATRAZINE


                                                      DICHLOBENIL
                    20
                       40
60
80
100
120
                    TIME-MINUTES  FROM  ONSET OF RAINFALL

                    Figure 14.  CUMULATIVE TOTAL HERBICIDE LOSS IN RUNOFF
                              AND ON SEDIMENT FROM DOTHAN, SITE 2.

-------
    100
CO
CO
o
_l
UJ
o
o
m
o:
UJ
UJ
>
80
    60
    40
    20
                                                     ATRAZINE

                                                     DICHLOBENIL
                20
                      40
60
80
100
120
                TIME-MINUTES  FROM  ONSET OF RAINFALL

                 Figure 15.  CUMULATIVE TOTAL HERBICIDE LOSS IN RUNOFF
                          AND ON SEDIMENT FROM RED BAY, SITE 5.

-------
      100
  CO
  CO
  O
  -I

  UJ
  Q
  o
  CD
  cc.
  UJ
p
UJ
Ol
     80
       60
       40
       20
   o
                                                          ATRAZINE


                                                          DICHLOBENIL
                   20
                           40
60
80
100
120
                   TIME-MINUTES  FROM  ONSET  OF RAINFALL
                   Figure 16.  CUMULATIVE TOTAL HERBICIDE LOSS IN RUNOFF AND

                            ON SEDIMENT FROM MALBIS  (BOWIE), SITE 6.

-------
    100
CO
CO
o
-I

UJ
Q

o

CQ
£
UJ
80
    60
o


Ul
40
2

o
20
                                                     ATRAZINE


                                                     DICHLOBENIL
                20
                      40
                                60
80
100
120
                 TIME-MINUTES  FROM ONSET OF RAINFALL

               Figure 17.  CUMULATIVE TOTAL HERBICIDE LOSS IN RUNOFF
                        AND ON SEDIMENT FROM MALBIS (BOWIE), SITE 7.

-------
   100
   80
o
o
g  60
LJ
    40
O
20
                                            • DOTHAN, SITE*2
                                            • MALBIS, SITE* 7
                                            A MALBIS, SITE** 6
                                            O RED BAY, SITE* 5
               20
                      40
60
80
100
                TIME-MINUTES  FROM ONSET OF RAINFALL
                    Figure 18.  CUMULATIVE LOSS OF AXRAZINE ON SEDIMENT.
120

-------
oo
      100
CO
CO
O
UJ
O
O
CD
a:
UJ
   UJ
   O
       60
       20
                                                • DOTHAN, SITE*2
                                                • MALBIS, SITE*?
                                                A MALBIS, SITE*6
                                                O RED BAY, SITE* 5
                   20
                          40
60
80
100
120
                   TIME-MINUTES  FROM  ONSET  OF RAINFALL
                    Figure 19. CUMULATIVE LOSS OF DICHLOBENIL ON SEDIMENT.

-------
-P-
VO
    CO
    CO
    o
    UJ
    o
    o
    CD
    (T.
    UJ
    o
       100
80
60
    UJ
        40
20
                                                  • ATRAZINE IN RUNOFF WATER
                                                  A ATRAZINE ON SEDIMENT
                                                  • DCBN IN RUNOFF WATER
                                                  O DCBN ON SEDIMENT
                    20
                       40
60
80
100
120
                    TIME-MINUTES  FROM  ONSET OF  RAINFALL
                         Figure 20.  CUMULATIVE HERBICIDE LOSS IN RUNOFF
                                  AND ON SEDIMENT FROM DOTHAN, SITE 2.

-------
    100
CO
CO
o
_J

UJ
o

o

CO
a:
UJ
UJ
    80
    60 -
    20
                                              • ATRAZINE IN RUNOFF WATER

                                              A ATRAZINE ON SEDIMENT


                                              • DC8N IN RUNOFF WATER

                                              O DCBN ON SEDIMENT
                20
                          40
60
80
100
120
                 TIME-MINUTES FROM ONSET OF RAINFALL
                    Figure 21.  CUMULATIVE HERBICIDE LOSS IN RUNOFF

                             AND ON SEDIMENT FROM RED BAY. SITE 5.

-------
      100
   CO
   S  80
o
03
OC
LJ

UJ
       60
Ol
        20
                                                  • ATRAZINE IN RUNOFF WATER
                                                  A ATRAZINE ON SEDIMENT
                                                  • DCBN IN RUNOFF WATER
                                                  O DCBN ON SEDIMENT
                    20
                           40
60
80
100
120
                    TIME-MINUTES FROM  ONSET OF RAINFALL
                      Figure 22.  CUMULATIVE HERBICIDE LOSS  IN RUNOFF AND
                                ON SEDIMENT FROM MALBIS (BOWIE), SITE 7.

-------
      100
   CO
   S   80
   UJ
   Q
   O
   CD
   tr
   UJ
60
-
   UJ
       40
       20
                                                • ATRAZINE IN RUNOFF WATER
                                                A ATRAZINE ON SEDIMENT
                                                • DCBN IN RUNOFF WATER
                                                O DCBN ON SEDIMENT
                   20
                      40
60
80
100
120
                   TIME-MINUTES  FROM  ONSET  OF RAINFALL
                       Figure 23.  CUMULATIVE HERBICIDE LOSS IN RUNOFF AND
                                ON SEDIMENT FROM MALBIS (BOWIE), SITE 7.

-------
solubility, the adaorpti.on-desorption equilibrium constant, and the
rate constants of the adsorption-desorption reaction.
     Rainfall throughout the event disperses and transports particulate
matter, preferentially the clay and organic fractions, from the zone of
erodibility in the runoff water.  The rate of herbicide loss is constant,
i.e., the cumulative loss curve increases, during that period in which
the loss is largely due to the transport of sediment.  However, when the
leaching action of the infiltrating water depletes the erodibility zone
of herbicide, the rate of herbicide loss decreases even though the rate
of sediment loss stabilizes.  A plateau region in the cumulative loss
curve is a result.  Herbicide loss in the runoff water during this time
is due to upward diffusion from a pesticide-rich zone below the erodi-
bility zone and through the pesticide-free zone into a film of laterally
moving water.
     The low herbicide loss rate in the sediment fraction continues
until the pesticide-free zone is stripped away by erosion, exposing a
layer of soil rich in the pesticide.  The herbicide loss rate again
increases, and the slope of the cumulative loss curve increases.  The
slope of the plateau region and its position on the curve is determined
by the .solubility of the herbicide, the extent and rate of adsorption
onto and desorption from the sediment, the permeability of the soil, and
the rate of infiltration.  The plateau appears to be more pronounced,
i.e., have a lesser slope, and the overall herbicide loss rate is lower
under conditions of high pesticide solubility, high soil permeability,
and high rate of infiltration, as indicated by the fraction of applied
water appearing as runoff and by the depth of the wetting front (Table
4).
     Another factor involved in the plateau phenomenon is the inter-
mittent or wave-action'phenomenon of sediment transport, especially of
non-suspended and lightly suspended materials.  As water begins to move
across a sloping soil surface, certain of the soil particles are moved
along in the flow.  As flow continues, additional soil particles are

                                   53

-------
added until the. kinetic forces involved are in balance.  Beyond this
point the system becomes overloaded and deposition begins to occur.
Then, the relatively clear water or at least unloaded runoff proceeds
downslope to begin again the process of entrainment, transport, and
deposition.  The process is readily observed in the field under natural
conditions and also during simulated rainfall tests on fallow soils.
Often during an event, sediment deposited at an earlier time in the
event is re-entrained and moved downslope.
     Since the greatest loss of herbicide coincides with the maximum
loss of clay-sized particles, the herbicides evidently attach preferen-
tially to the clay particles.  The data do not permit further specifica-
tion of the size of particles responsible for herbicide transport.

Phase Distribution
     For both compounds on all soils,  the concentration (ppm) of herbi-
cide was greater in the sediment than in the runoff; however, since much
more water ran off than sediment, the greater absolute loss (70-80% of
total) was associated with the water fraction (Tables 5-8).  Although a
high concentration of herbicide in the sediment suggests that the com-
pounds are adsorbed onto the clay and silt particles, the evidence is
inconclusive.  Since the equilibration time in the soil following
application and incorporation was short (less than 1 hour)  prior to onset
of rainfall, a favorable condition existed for the mass transport of
herbicide off the soil surface.  A portion of the herbicide in the sedi-
ment may therefore have been in the form of wettable powder particles
rather than adsorbed onto the eroded soil.
     The concentrations of atrazine from Site 2 (after 80 minutes) and
of dichlobenil from Site 7 (after 95 minutes) in the runoff were below
the detection limit of the analytical method used.  The respective
sediment fractions, however,  showed appreciable herbicide concentration.
Apparently the herbicide in these cases was bound very tightly to the
sediment•
                                    54

-------
     The particle size distribution of the sediment changed with time
during the runoff event and was at all times different from that of the
surface soil.  The degree of variation in particle size and its vari-
ation with time differ from soil to soil.  In general, however, the
fraction of the sediment represented by clay and silt decreased with
time, leveling off at a constant value about 40-50 minutes after the
onset of rainfall.  The greatest proportion of the total herbicide loss
in sediment occurred during this early period (Tables 9-12).   The early
preferential loss of clay and organic matter may account for the high
rate of herbicide loss early in the runoff event.  After 60 minutes, the
particle size distribution in the sediment stabilized (Figures 5-7).  In
Sites 2 and 5 the clay content stabilized at a concentration about twice
that present in the surface soil.
     The percent herbicide loss increased as the total volume of runoff
increased.  However, more data are required to determine a relationship
among the herbicide loss in runoff, the total herbicide loss, and the
volume of runoff water.

ENVIRONMENTAL IMPLICATIONS
     The runoff of agricultural pesticides presents an environmental
hazard through the toxicity of such chemicals to natural aquatic
organisms.  The LD „ (lethal dose for 50% fatality) of dichlobenil ranges
from 10 to 20 ppm for pumpkin seed (Liopmis gibbosus) , bluegill (L_.
macroberus) , redear sunf ish (L_. microlophus) , and largemouth bass
(Micropterus salmoides) (Walker, 1964).  Vivier and Nesbet (1965) found
that exposure of minnows to 0.5 ppm atrazine for 48 hours had no signi-
ficant effects; concentrations of 5 and 10 ppm, however, were lethal to
minnows at 48 and 6 hours, respectively.
     The herbicide concentrations measured in the runoff water in the
present study were  therefore  below levels necessary to exert acute
toxic effects for the above organisms.  However, the concentrations.on
the sediment were such that the herbicides could produce toxic effects

                                   55

-------
             Table 9.  PERCENT CUMULATIVE AND FRACTIONAL LOSS
                    OF HERBICIDES ON DOTHAN, SITE 2
Time From
Onset of
Rainfall,
Min.
9
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
Cumulative , %

Atrazine
Sediment Water
0
14
22
30
38
43
48
52
55
58
60
62
63
66
68
70
72
78
85
92
97
99
100
0
12
24
41
47
53
60
70
78
84
89
91
94
97
100









Total
0
13
24
38
45
50
57
65
72
76
81
83
85
88
91
91
92
94
96
98
99
100
100

Dichlobenil
Sediment Water
0
11
23
34
40
49
53
54
55
56
56
57
57
60
62
64
66
75
86
94
99
100
100
0
10
18
25
37
44
52
58
64
69
73
75
77
80
82
85
87
90
93
95
98
99
100

Total
0
10
19
27
38
46
54
59
65
69
73
75
77
79
82
84
87
91
95
95
98
99
100
Fractional
in Sediment
Water
Atrazine
0
0.77
0.66
0.87
0.39
0.34
0.38
0.49
0.44
0.26
0.26
0.14
0.14
0.15
0.18
0.04
0.05
0.09
0.11
0.13
0.08
0.03
0.02
Loss
and
DCBN
0
0.28
0.23
0.23
0.29
0.20
0.21
0.16
0.14
0.11
0.10
0.06
0.06
0.07
0.07
0.07
0.07
0.10
0.10
0.09
0.08
0.03
0.03
123 (Runoff stopped)
                                   56

-------
         Table 10.  PERCENT CUMULATIVE AND FRACTIONAL LOSS OF
                     HERBICIDES ON RED BAY, SITE 5
Time From
Onset of
Cumulative, %
Rainfall, Atrazine
Min.
6
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
Sediment
0
14
21
25
29
32
39
45
51
57
63
69
74
79
83
87
91
94
96
97
98
99
99
100
Water
0
14
30
40
48
53
55
59
63
65
68
70
73
75
78
79
82
86
89
92
95
97
99
100
Total
0
14
29
38
45
50
53
57
61
64
67
70
73
76
79
80
84
87
90
93
95
97
99
100
Fractional Loss
in Sediment and
Dichlobenil Water
Sediment
0
14
26
36
44
49
55
60
65
69
74
77
80
83
86
88
90
92
94
95
96
98
99
100
Water
0
4
12
18
24
27
31
37
44
50
56
60
63
68
72
76
80
84
87
91
93
96
98
100
Total
0
7
15
22
28
32
36
43
49
54
60
64
67
71
75
79
82
86
89
92
94
97
98
100
Atrazine
0
1.73
1.90
1.20
0.92
0.57
0.41
0.50
0.51
0.40
0.37
0.36
0.37
0.37
0.36
0.18
0.46
0.48
0.38
0.29
0.29
0.29
0.19
0.15
DCBN
0
0.66
0.89
0.72
0.63
0.38
0.41
0.65
0.63
0.59
0.56
0.38
0.35
0.39
0.41
0.39
0.35
0.32
0.31
0.31
0.26
0.24
0.19
0.17
123 (Runoff stopped)
                                  57

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          Table 11.  PERCENT CUMULATIVE AND FRACTIONAL LOSS
                OF HERBICIDES ON MALBIS (BOWIE), SITE 6
Time From
Onset of
Cumulative, 7=>
Rainfall, Atrazine
Min.
3
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
Sediment
0
23
32
39
45
50
53
a
a
a
a
a
a
54
56
59
62
66
70
76
81
87
95
100
Water
0
21
31
38
43
48
53
58
60
63
66
68
71
74
76
79
81
84
87
89
92
95
97
100
Total
0
21
31
38
43
48
53
57
59
61
63
66
68
70
73
76
78
81
84
87
90
93
97
100
Dichlobenil
Sediment
0
25
36
43
49
54
56
57
57
60
64
68
72
75
78
81
83
86
89
91
94
96
98
100
Water
0
9
16
22
28
33
38
42
46
50
56
61
66
70
74
77
80
84
87
91
95
97
99
100
Total
0
14
23
29
35
40
44
47
50
54
58
63
68
72
75
79
82
85
88
91
95
97
99
100
Fractional Loss
in Sediment and
Water
Atrazine
0
2.48
1.19
0.84
0.61
0.60
0.51
0.49
0.24
0.26
0.27
0.26
0.26
0.30
0.31
0.31
0.29
0.34
0.35
0.37
0.36
0.40
0.41
0.37
DCBN
0
1.29
0.76
0.54
0.55
0.46
0.32
0.26
0.26
0.35
0.43
0.45
0.37
0.35
0.35
0.28
0.26
0.27
0.28
0.34
0.28
0.20
0.18
0.11
124 (Runoff stopped)

a  GC results are questionable due to interfering background material.
                                   58

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          Table  12.   PERCENT  CUMULATIVE AND FRACTIONAL LOSS
              OF HERBICIDES  ON MALBIS  (BOWIE),  SITE  7
Time From
Onset of
Cumulative, %
Rainfall, Atrazine
Min.
6
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
Sediment
0
6
13
16
19
22
25
27
30
36
43
52
60
62
64
67
69
72
75
78
82
88
94
100
Water
0
5
15
23
31
38
43
49
54
60
65
70
74
78
81
85
87
89
91
93
94
96
98
100
Total
0
5
15
21
28
33
38
42
47
52
59
65
70
73
76
79
82
84
86
88
91
94
97
100
Fractional Loss
in Sediment and
Dichlobenil
Sediment
0
10
23
31
38
44
49
54
59
65
69
73
76
78
81
84
86
89
91
93
95
97
99
100
Water
0
5
19
29
37
44
49
55
58
64
70
75
81
85
88
91
94
97
100





Total
0
8
21
30
37
44
49
54
59
64
70
74
78
81
84
87
90
92
95
96
97
98
99
100
Water
Atrazine
0
0.50
0.92
0.61
0.65
0.53
0.48
0.43
0.43
0.55
0.58
0.61
0.46
0.32
0.31
0.33
0.23
0.20
0.20
0.22
0.23
0.29
0.30
0.31

DCBN
0
0.36
0.62
0.40
0.35
0.30
0.23
0.25
0.21
0.24
0.25
0.20
0.20
0.14
0.13
0.13
0.13
0.12
0.12
0.05
0.05
0.04
0.04
0.04
122 (Runoff stopped)
                                  59

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depending upon the following conditions:  (1) the mode of uptake of the
organism, (2) the bioactive threshold of the organism for the pesticide,
(3) the rate with which the pesticide desorbs from the sediment surface,
(4) the equilibrium distribution of the pesticide between the water and
sediment, and (5) the site of adsorption (internal or external portion
of the particle).
     Although the major impact of herbicides in washoff from agricultural
lands is the long-term chronic or sub-lethal effect on the aquatic eco-
system, the chemicals also affect other segments of the environment
through the many uses of water.
     Factors determining the environmental impact of pesticides in agri-
cultural runoff are (1) the toxicity of the pesticide and its degradation
products and metabolites ;  (2) the pesticide application rate and the
extent of usage; (3) the runoff characteristics; and (4) the persistence,
accumulation, and magnification in the aquatic ecosystem.

FIELD PROCEDURE EVALUATION
     The rainulator provides an efficient means of studying pesticide
runoff and soil erosion from agricultural land under conditions of high
intensity.  It may be transported easily by truck from site to site
together with a 5,000-gallon tanker as a water supply.  All variables of
storm and soil conditions, including the time between pesticide applica-
tion and the onset of the storm, can be controlled.  Information that
would take years to gather using only natural rainfall may be obtained
in a relatively short period of time.
     A field laboratory set up in a large shed proved sufficient for
sample separation, extraction, and concentration.  An air-conditioned
facility, however, was required to house the gas chromatograph.  A small
trailer was provided for this purpose.  Prior to any field study, the
power requirements (especially voltage stability), ventilation, lighting,
and work space should be thoroughly examined.
                                   60

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     Analyses of samples at the field site closely correlated with, those
of samples sent to the home laboratory  (SERL), demonstrating the feasi-
bility of gas chromatographic analysis  on site.

FUTURE NEEDS
     A pesticide runoff mathematical model is vitally needed and must be
formulated and used as a management tool to predict pesticide losses in
runoff and on eroded soil.  The basic variable in such a model would be
(1) climatic factors, e.g., rainfall intensity, amount, frequency, and
distribution, (2) soil properties,  (3)  physicochemical properties and
formulation of the pesticide,  (4) kinetics of the processes responsible
for pesticide attenuation in the soil,  (5) hydrologic and sediment trans-
port submodels, and (6) watershed characteristics.
     Using information from the model,  the Pesticide Registration Branch
will be able to determine the suitability of a given pesticide, as
formulated, region by region.  If adverse runoff behavior is predicted
from a given formulation, registration  could be denied until a suitable
formulation is devised.  This approach  will permit selective registration
of a pesticide for a given geographical region.  Currently a pesticide
proven to be environmentally detrimental in one region is denied registra-
tion throughout the country.  Recommendation and clearance for selective
pesticide use on small acreages would be possible with the availability
of a viable pesticide runoff mathematical model.
                                     61

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                               SECTION yi

                               REFERENCES
Bailey, G.W.  Entry of biocidea in watercourses.  Proc. Symposium on
Agri. Wastewaters.  California Water Resources Center Report.  10:94-
104, 1966.

Bailey, G.W., R.R. Swank, Jr., and H.P- Nicholson.  Predicting pesticide
runoff from agricultural land:  A conceptual model.  J. Environ. Quality.
[Accepted for publication 1973].

Bailey, G.W. and J.L. White.  Factors influencing the adsorption, desorp-
tion and movement of pesticides in soil.  Residue Rev.  32:29-92, 1970.

Barnett, A.P., E.W. Hauser, A.W. White, and J.H. Holladay.  Loss of 2,4-D
in washoff from cultivated fallow land.  Weed Sci.  15:133-137, 1967.

Benfield, C.A. and E.D. Chilwell.  The determination of some triazine
herbicides by gas-liquid chromatography with particular references to
atrazine in soil.  Analyst.   89:475-479, 1964.

Briggs, G.G. and J.E. Dawson.  Hydrolysis of 2,6-dichlorobenzonitrile in
soils.  J. Ag. and Food Chem.  18:97-99, 1970.

Cobb, C., A.P. Barnett, and J.S. Rogers.  Manmade rainstorms, a new tool
for erosion research.  Ga. Agr. Research.  2(4):2, 1961.

Day, P.R.  "Fractionation and Particle-size Analysis."  In: Methods of
Soil Analysis, C.A. Black, (ed.).  Madison, Wisconsin, Amer. Soc. of
Agronomy, 1965.  Part 1, pp 547-556.

Grzenda, A.R., H.P. Nicholson, J.I. Teasley, and J.H. Patric.  DDT resi-
dues in mountain stream water as influenced by treatment practices.  J.
Econ. Entomol.  57:615-618, 1964.

Hall, J.K., M.Pawlus, and E.R. Higgins.  Losses of atrazine in runoff
water and soil sediment.  J. Environ. Quality.  1:172-176, 1972.

Hayes, M.H.B.  Adsorption of triazine herbicides on soil organic matter,
including a short review on soil organic matter chemistry.  Residue Rev.
32:131-174, 1970.

Hershfield, D.M.  Rainfall frequency atlas of the United States for
durations from 30 minutes to 24 hours and return periods from 1 to 100
years.  U.S. Department of Commerce, Weather Bureau Tech.  Paper No. 40.
1961.      ~~——

                                    62

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Lauer, G.J., H.P. Nicholson, W.S. Cox, and J.I. Teasley.  Pesticide
contamination of surface waters by sugar cane farming in Louisiana.
Trans. Amer. Fisheries Soc.  95:310-316, 1966.

McGlamery, M.D., F.W. Slife, and K. Butler.  Extraction and determination
of atrazine from soil.  Weeds.  15:35-38, 1967.

Meyer, L.D.  Use of the rainulator for runoff plot research.  Soil
Science Soc. Amer. Proc.   24:319-322, 1960.

Meyer, L.D.  Simulation of rainfall for soil erosion research.  Trans.
Am. Soc. Agr. Engrs.  8:63-65, 1965.

Meyer, L.D., and D.L. McCune.  Rainfall simulator for runoff plots.  Ag.
Engineering.  39:644-648,  1958.

Miller, C.W., I.E. Demoranville, and A.J. Charig.  Persistence of
dichlobenil in cranberry bogs.  Weeds.  14:296-298, 1966.

Nicholson, H.P., A.R. Grzenda, G.J. Lauer, W.S. Cox, and J.I. Teasley.
Water pollution by insecticides in an agricultural river basin.   I.
Occurence in river and treated municipal water.  Limnol. Oceanog.  9:310-
317, 1964.

Nicholson, H.P., A.R. Grzenda, and J.I. Teasley.  Water pollution by
insecticides.  A six and one-half year study of a watershed.  Proc.
Symposium Agri. Waste Water, California Resources Center.  10:132-141,
Davis, California, 1966.

Nicholson, H.P., H.J. Webb, G.J. Lauer, R.E. O'Brien, A.R. Grzenda, and
D.W. Shanklin.  Insecticide contamination in a farm pond.  Part I.  Origin
and duration.  Trans. Amer. Fisheries Soc.  91:213-222,  1962.

Payne, W.R., Jr., and G.W. Bailey.  Interactions of nitrile, carbamate
and uracil pesticides with montmorillonite.  Agronomy Abstracts,  p. 79,
1969.

Russell, J.D., M.I. Cruz,  J.L. White, G.W. Bailey, W.R. Payne, Jr.,
J.D. Pope, Jr., and J.I. Teasley.  Mode of chemical degradation of
s-triazines by montmorillonite.  Science.  160:1340-1342,  1968.

Sheets, T.V., and P.C. Kearney.  Extraction of some triazine herbicides
from soils.  Weed Soc. Amer. Abstr.  p. 10, 1964.

Trichell, D.W., H.L. Morton, and M.G. Merkle.  Loss of herbicide in runoff
water.  Weeds.  16:447-449, 1968.
                                    63

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Van Vali.n, C.C.  Persistence of 2,6-<-dichlorohenzonitrile in aquatic
environments.  Ady. In Chem. Series.  6Q;271-279, 1966.

Vivier, P., and M. Nishet.  Toxicity of some herbicides, insecticides,
and industrial wastes.  U.-S. Public Health Service Publ.  No. 999.  WP
25, pp. 167-169, 1965.

Walker, C.R.  Dichlobenil as a herbicide in fish habitats.  Weeds
12:267-269, 1964.

White, A.W., A.P. Barnett, E.G. Wright, and J.H. Holladay.  Atrazine
losses from fallow land caused by runoff and erosion.  J. Environ. Sci.
& Tech.  1:740-744, 1967.

Wischmeier, W.H., and O.D. Smith.  Predicting rainfall erosion losses
from cropland east of the Rocky Mountains; guide for selection of
practices for soil and water conservation.  Agricultural Handbook.
No. 82, ARS, p. 47, 1965.

Wischmeier, W.H.  A rainfall erosion index for a unversal soil loss
equation.  Soil Sci. Amer. Proc.  23:246-249,  1959.
                                   64

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                               SECTION VII
                                GLOSSARY

Control Site—herbicide treated plot without simulated (artificial)
     rainfall.
Erodibility Zone—portion of surface horizon, the thickness of which is
     measured from the surface downward, that will be eroded awary
     during a rainfall event.
Pesticide-Free Zone—the soil surface or an incremental layer between
     the soil surface and the pesticide-rich zone through which the
     downward moving pesticide has passed.
Pesticide-Rich Zone—the soil surface or incremental layer at some
     finite distance downward from the soil surface where all or the
     remaining amount of the applied pesticide resides.
Plow Pan—a compacted layer of soil semi-permeable to percolating water,
     resulting from repeated use of conventional agricultural equipment.
Runoff—water that moves over the soil surface.
Sediment—soil lost by the erosional process.
Soil Loss—synonomous with the term sediment.
Washoff—collective movement of water, sediment, and pesticide from the
     surface of agricultural soils.
Water Loss—synonomous with runoff.
                                 65

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                              SECTION -VIII




                               APPENDICES




                                                                   Page




A.   Photographs Showing Operation of the Rainfall Simulator        67




B.   Soil Classification descriptions                               76




C.   Basic analytical data                                          83
                                   66

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                              Appendix A


                     Photographs Showing Operation

                       of the Rainfall Simulator
Figure 1.  General view of rainfall simulator during a soil erodibility-
           pesticide transport test on Dothan sandy loam soil.

Figure 2.  A data collection center; instantaneous samples of runoff
           water and sediment are collected for analysis of soil and
           pesticide content.

Figure 3.  Precision application of pesticides on a test plot after
           plowing (several Weeks earlier), rotatilling, leveling, and
           smoothing by hand.

Figure 4.  After raking by hand to stir pesticide into surface a section
           of a spike tooth drag harrow is pulled up slope to provide
           the final finished surface configuration.

Figure 5.  Site 2 after 30 minutes of rain (3.2 cm), looking downslope.
           Runoff began in 9 minutes.

Figure 6.  Site 2 after 60 minutes of rain (6.4 cm), looking downslope.

Figure 7.  Site 2 after 90 minutes of rain (9.5 cm), looking downslope.

Figure 8.  Site 2.  Rainfall ending after 120 minutes (12.5 cm of rain-
           fall); note smooth plot surface.
                                     67

-------
Figure 1.  GENERAL VIEW OF RAINFALL SIMULATOR DURING A SOIL ERODIBILITY-
           PESTICIDE TRANSPORT TEST ON DOTHAN SANDY LOAM SOIL.
                                    68

-------
Figure 2.  A DATA COLLECTION CENTER: INSTANTANEOUS SAMPLES OF RUNOFF
           WATER AND SEDIMENT ARE COLLECTED FOR ANALYSIS OF SOIL AND
           PESTICIDE CONTENT.
                                    69

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Figure 3.   PRECISION APPLICATION OF PESTICIDES ON A TEST PLOT AFTER
           PLOWING (SEVERAL WEEKS EARLIER), ROTATILLING, LEVELING,
           AND SMOOTHING BY HAND.
                                   70

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Figure 4.  AFTER RAKING BY HAND TO STIR PESTICIDE INTO SURFACE A SECTION
           OF A SPIKE TOOTH DRAG HARROW IS PULLED UP SLOPE TO PROVIDE
           THE FINAL FINISHED SURFACE CONFIGURATION.
                                    71

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Figure 5.  SITE 2 AFTER 30 MINUTES OF RAIN (3.2 cm), LOOKING DOWNSLOPE,
           RUNOFF BEGAN IN 9 MINUTES.
                                    72

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Figure 6.  SITE 2 AFTER 60 MINUTES OF RAIN  (6.4 cm), LOOKING DOWNSLOPE.
                                     73

-------
Figure 7.  SITE 2 AFTER 90 MINUTES OF RAIN (9.5 cm),  LOOKING DOWNSLOPE.
                                    74

-------
Figure 8.  SITE 2.  RAINFALL ENDING AFTER 120 MINUTES (12.5 cm of
           rainfall); NOTE SMOOTHED PLOT SURFACE.
                                    75

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                               APPENDIX B
                    SOIL CLASSIFICATION DESCRIPTIONS

A.  Site #2.
    Henry County, Wiregrass Substation, Headland, Alabama; northeast of
    headquarters, just north, of field planted to cotton.
        Typifying Pedon;  Dothan sandy loam (lab analysis sandy loam).
        Classification, Present;  Plinthic Paleudult; fine-loamy,
        siliceous, thermic family.
        Classification, Former;  Red-Yellow Podzolic.
        Use and Native Vegetation;  Presently used as cropland (cotton
        and corn for silage).   Native vegetation is longleaf pine and
        hardwoods.
        Parent Rock or Regolith;  Unconsolidated marine sediments.
        Geomorphology;  Region:  Coastal Plain MLRA-133.
                        Position:  Upland.
                        Elevation:  Not recorded.
        Drainage and Permeability:  Well drained and moderately permeable.
        Water Table and Duration;  Below 6 ft throughout year except for
        occasional perched water table above layers with plinthite.
        Slope:  2% (test plot  2.2%).
        Effective Rooting Depth:  6 ft.
        Described by:  R.L. Guthrie.         Date;  October 23, 1970.
        Pedon Descriptions;
        A       0-7"       Brown (10YR 5/3) sandy loam; weak fine gran-
                           ular structure; very friable; few iron concre-
                           tions; strongly acid; abrupt smooth boundary.
        B       7-11"      Yellowish brown (10YR 5/6) sandy loam; weak
                           fine subangular blocky structure; friable;
                           very strongly acid; clear smooth boundary.
                11-36"     Yellowish brown (10YR 5/8) sandy clay loam;
                                   76

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                           moderate fine subangular blocky structure;
                           friable; thin patchy clay films on ped faces;
                           very strongly acid; gradual boundary.
        B22t    36-48"     Yellowish brown  (10YR 5/8) sandy clay loam
                           with common medium distinct strong brown
                           (7.SYR 5/8), yellowish red (SYR 5/8) mottles;
                           moderate fine subangular blocky structure;
                           friable, but firm around areas of plinthite;
                           thin patchy clay films on ped faces; 2 to 5%
                           plinthite nodules; few iron concretions; very
                           strongly acid; gradual boundary.
        B23t    48-62"     Mottled yellowish brown (10YR 5/8), strong
                           brown (7.SYR 5/8), light gray 10YR 7/2), and
                           yellowish red (SYR 5/8) sandy clay loam; weak
                           fine subangular blocky structure; friable but
                           firm around areas of plinthite; thin patchy
                           clay films on ped faces; 5 to 10% plinthite
                           nodules; very strongly acid.
        Mean Temperature:  Not recorded.
        Mean Precipitation;  Not recorded.

B.  Site #5.
    Baldwin County, Alabama,  Gulfcoast Substation, 0.2 miles south of
    office, 750 ft west of field road, 75 ft south of field border in
    the SE 1/4, NW 1/4, NE 1/4, Sec. 9, R2E, T6S.
        Typifying Pedon;  Red Bay fine sandy loam (lab analysis sandy
        loam).
        Classification:  Rhodic Paleudult;  fine loamy, siliceous, thermic.
        Use and Native Vegetation;   Presently used for row crops (soy-
        beans).  Native vegetation is believed to have been longleaf and
        loblolly pine, dogwood, and various oaks.
                                  77

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        Parent Rock or Regolith,;  Thick beds  of  unconsolidated  sandy clay
        loams and  sandy  loams.
        Geomorphology:   Region:   Coastal  Plain MLRA-133.
                        Position:  Upland.
                        Elevation:  About 105 ft.
        Drainage and Permeability;  Well  drained.   Permeability is
        moderate.
        Water Table and  Duration;  Below- 10 ft ttiroughout  year.
        Slope;   2% (test plot  2.5%).
        Effective  Rooting Depth:  50  in.  plus.
        Described  by; M.G. Mattox.           Date:   October  21,  1970.
        Pedon Descriptions;
        A       0-9"      Dark  reddish brown (SYR  3/3)  fine sandy loam;
         P
                          weak  fine  granular structure; friable;  slightly
                          acid;  abrupt  smooth boundary.
        B       9-14"     Dark  reddish brown (2.SYR 3/4)  light sandy
                          clay  loam; weak medium subangular blocky
                          structure; friable; slightly  acid; clear wavy
                          boundary.
        B       14-62"     Dark  red  (2.SYR 3/6)  heavy sandy  clay loam;
                          weak  medium subangular blocky structure;
                          friable; medium acid;  gradual wavy boundary.
        B22t    62-70"     Dark  red  (10R 3/6) sandy clay loam;  weak
                          medium subangular  blocky structure;  friable;
                          very  strongly  acid.
        Mean Temperature; Annual 67°F.
        Mean Precipitation;  Annual  65 in.

C.  Site #6.
    Baldwin Country, Alabama,  Gulfcoast  Substation, 0.25 miles  south of
    office, then 0.35 miles  east-southeast to woods near pond and 425 ft
    north in field in the SW 1/4, NW 1/4, NE  1/4, Sec. 9,  R2E,  T6S.

                                   78

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Typifying Pedon;  Malbis fine sandy loam  (lab analysis sandy
clay loam).
Classification;  Plinthi.c Paleudult; fine loamy, siliceous,
thermic.
Use and Native Vegetation;  Present use is cropland (corn and
silage—wheat winter cover).  Native vegetation is believed to
have been longleaf and loblolly pine, dogwood, and gallberry.
Parent Rock or Regolith;  Thick, beds of unconsolidated loams,
sandy clay loams, and clay  loams.
Geomorphology;  Region:  Coastal Plain MLRA-133
                Position:   Upland.
                Elevation:  About 110 ft.
Drainage and Permeability;  Moderately well drained.  Permeabil-
ity  is moderate in upper B and moderately slow in lower B .
Water Table and Duration;   30 to 50 in. for short periods in
winter and spring months.
Slope;  2% (test plot 3.6%).
Effective Rooting Depth;  50 in. plus.
Described by;  M.G. Mattox.           Date;  October 21, 1970.
Pedon Descriptions;
A       0-8"       Dark grayish brown (10YR 4/2) fine sandy
                   loam; weak fine granular structure; friable,
                   about 2% iron concretions; slightly acid;
                   abrupt smooth boundary.
B       8-26"      Yellowish brown  (10YR 5/6) light clay loam;
                   weak medium subangular blocky structure;
                   friable, slightly sticky when wet; about 4%
                   iron concretions; medium acid; gradual wavy
                   boundary.
B       26-40"     Strong brown  (7.SYR 5/6) light clay loam
                   with few medium prominent red (2.5YR 4/6)
                            79

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                          and few medium distinct yellowish brown
                          (10YR 5/8)  and light yellowish brown
                          (10YR 6/4) mottles; weak medium subangular
                          blocky structure; friable, slightly sticky
                          when wet; about 4% iron concretions; about
                          5% plinthite; very strongly acid; gradual
                          wavy boundary.
                40-52"     Mottled strong brown  (7.SYR 5/6), yellowish
                          brown  (10YR 5/6), yellow  (10YR 7/6) and  red
                           (2.5YR 4/6) light clay loam; weak medium
                          subangular blocky structure; friable;
                          plinthite nodules are firm; slightly sticky
                          when wet; about 7% plithite nodules; very
                          strongly acid; gradual wavy boundary.
        B       52-66"     Mottled yellowish brown  (10YR 5/6), light
                          yellowish brown  (2.5Y 6/4), yellow  (2.5Y 7/6),
                          strong brown  (7.5YR 5/6),  red  (2.SYR 4/6),
                          and light gray  (10YR  7/2)  heavy sandy  clay
                          loam; weak medium subangular blocky structure;
                          firm, friable in light gray and yellow areas;
                          about 10% plinthite nodules; very strongly
                          acid.
        Mean Temperature:  Annual  67°F.
        Mean Precipitation:  Annual  65 in.

D.  Site #7-
    Baldwin County,  Alabama, Gulfcoast Substation,  225 ft east-northeast
    of silos at dairy barn in  the  SW 1/4,  SW 1/4, Sec. 4, R2E, T6S.
        Typifying Pedon;   Malbis fine sandy loam (lab analysis  sandy
        loam).
        Classification;   Plinthic  Paleudult; fine loamy  siliceous,
        thermic.
        Use and Native Vegetation;   Present use  is  cultivation (millet

                                    80

-------
for grazing—wheat cover crop).  Native vegetation is believed
to be longleaf and loblolly pine, dogwood, and gallberry.
Parent Rock or Regolith;  Thick beds of unconsolidated loams,
sandy clay loams, and clay loams.
Geomorphology;  Region:  Coastal Plain MLRA-133.
                Position:  Upland
                Elevation:  About 100 ft.
Drainage and Permeability;  Moderately well drained.  Permeabil-
ity is moderate in upper B  and moderately slow in lower B .
Water Table and Duration;  30 to 50 in. for short periods in
winter and spring months.
Slope;  4% (test plot 5.7%).
Effective Rooting Depths  50 in. plus.
Described by:  M.G. Mattox.          Date;  October 21, 1970.
Pedon Descriptions:
A       0-7"       Brown (10YR 4/3) fine sandy loam; weak fine
                   granular structure; friable; about 3% iron
                   concretions; medium acid; abrupt smooth
                   boundary.
B21t    7-29"      Yellowish brown (10YR 5/6) sandy clay loam;
                   weak medium subangular blocky structure;
                   friable, slightly sticky when wet; about 4%
                   iron concretions; strongly acid; gradual
                   wavy boundary.
B22t    29-39"     Yellowish brown (10YR 5/6) sandy clay loam
                   with few medium distinct strong brown (7.SYR
                   5/6) and few medium prominent red (2.5YR 4/6)
                   mottles; weak medium subangular blocky
                   structure; friable, slightly sticky when wet;
                   about 4% iron concretions; about 4% plinthite
                   nodules; strongly acid; gradual wavy boundary.
                           81

-------
        39-54"     Yellowish brown (10YR 5/6) sandy clay loam
                   with common medium distinct strong brown
                   (7.5YR 5/6), common medium prominent red
                   (2.5YR 4/6), and few medium faint light
                   yellowish brown (2.5Y 6/4) mottles; weak
                   medium subangular blocky structure; friable,
                   plinthite nodules are firm; about 4% iron
                   concretions; about 8% plinthite nodules;
                   very strongly acid; gradual wavy boundary.
        54-66"     Mottled yellowish brown (10YR 5/6), light
                   gray (10YR 7/2), strong brown (7.SYR 5/6),
                   yellowish red (5YR 4/8), red (2.SYR 4/6),
                   and light yellowish brown (2.5Y 6/4) sandy
                   clay loam; moderate medium subangular blocky
                   structure; firm; about 15% plinthite nodules;
                   very strongly acid.
Mean Temperature;  Annual 67°F.
Mean Precipitation;  Annual 65 in.
                           82

-------
                               APPENDIX C
                         BASIC ANALYTICAL DATA

Wiregrass
Site #2, Plot #1:  Dothan Soil Type, 2.2% Slope
Dothan, Alabama

    Plot Size	 1.83 m x 10.7 m
                                              (6.00 ft x 35.0 ft)
    Application Rate:
      Casoron (50% dichlobenil)               13.4 kg/ha (12.0 Ib/A)
        Total Casoron applied                 27.2 g
        Total Dichlobenil (DCBN) applied      13.6 g (6.70 kg/ha)
      Aatrex (80% atrazine)                   2.11 kg/ha (1.88 Ib/A)
        Total Aatrex                          4.26 g
        Total Atrazine                        3.24 g (1.60 kg/ha)
About 690 gallons of water was applied over 120 minutes.  Runoff began
at 9 minutes, samples were collected at specified  time intervals during
rainfall and after the rainfall had stopped (120 minutes); runoff ended
at 123 minutes.
    Results:
    1.  Total applied rainfall                13.2 cm (5.27 in.)
        Total runoff  (calculated)             8.64 cm (3.40 in.)
        Total sediment runoff  (calculated)    7.05 kg (15.5 Ib)
    2.  Sediment runoff
        Sediment (SERL)                       3.47 x 103 kg/ha (1.55 T/A)
        Sediment and sandy (USDA)             7.35 x 103 kg/ha (3.28 T/A)
    3.  Atrazine recovered
        Total in sediment                     62.2 mg
        Total in water runoff                 145 mg
        Total recovered                       207 mg
                                    83

-------
4.  Atrazlne loss (% of applied)
    In sediment                                    1.95%
    In water runoff                                4.49%
    Total                                          6.44%
5.  Dichlobenil recovered
    Total in sediment                              48.6 mg
    Total in water runoff                          321 mg
    Total recovered                                370 mg
6.  Dichlobenil loss (% of applied)
    In sediment                                    0.36%
    In water runoff                                2.36%
    Total                                          2.72%
                                84

-------
                  INCREMENTAL SOIL,  WATER,  AND HERBICIDE LOSSES IN SEDIMENT AND WATER
                                        (English and Metric Units)
                            (Beginning with minute 9,  first increment = 6 min,
                          subsequent increments = 5 min,  final increment = 3 min)

                                              Dothan Site #2
Minute
9
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
123
Soil
T/A
.000
.089
.114
.104
.087
.097
.090
.093
.090
.075
.066
.055
.057
.062
.060
.056
.056
.065
.066
.068
.060
.032
.026
Losses
kg /ha
0
200
256
233
195
217
202
208
202
168
148
123
128
139
134
126
126
146
149
152
134
72
58
Water
Losses
in. cm
.000 .000
.107 .272
.111 .282
.120 .305
.131 .333
.144 .366
.145 .368
.145 .368
.145 .368
.150 .381
.151 .384
.155 .394
.157 .399
.165 .419
.165 .419
.170 .432
.170 .432
.180 .457
.175 .444
.175 .444
.175 .444
.175 .444
.176 .447
(Runoff stopped)
Herbicide Losses
Ib/acre
Sediment

Water
Atrazine DCBN Atrazine
.000
.002
.002
.002
.002
.001
.001
.001
.001
.001
.001
.000
.000
.001
.001
.001
.001
.001
.002
.002
.002
.000
.000

000
002
003
002
001
002
001
000
000
000
000
000
000
000
000
000
001
002
002
002
001
000
000

000
008
008
Oil
004
004
004
006
006
003
003
002
002
002
002
000
000
000
000
000
000
000
000


DCBN
.000
.015
,011
.011
.016
.010
.012
.009
.008
,007
.006
.003
.003
.004
.004
.004
.004
.004
.004
.004
.003
.002
.002

kg /ha
Sediment
Atrazine
.000
.002
.002
.002
.002
.001
.001
.001
.001
.001
.001
.000
.000
.001
.001
.001
.001
.001
.002
.002
.002
.000
.000

Water
DCBN Atrazine
.000
.002
.003
.002
.001
.002
.001
.000
.000
.000
.000
.000
.000
.000
.000
.000
.001
.002
.002
.002
.001
.000
.000

.000
.009
.009
.012
.004
.004
.004
.007
.007
.003
.003
.002
.002
.002
.002
.000
.000
.000
.000
.000
.000
.000
.000


DCBN
.000
.017
.012
.012
.018
.011
.013
.010
.009
.008
.007
.003
.003
.004
.004
.004
.004
.004
.004
.004
.003
.002
.002

CO
Ui

-------
Wiregrass                                          Time  Period  Losses
Site #2, Plot #1:  Dothan Soil Type,  2.27% Slope
       3 min.
Time (min)


  9
 15
 20
 25
 30
 35
 40
 45
 50
 55
 60
 65
 70
 75
 80
 85
 90
 95
100
105
110
115
120
123
 Soil and Water Losses
   Soil       Water
    Ib
   .000
   .890
  1.144
  1.036
   .866
   .968
   .896
   .925
   .900
   .750
   .657
   .550
   .570
   .620
   .596
   .555
   .563
   .650
   .655
   .675
   .597
   .320
   .264
 in.
.000
.107
.111
.120
.131
.144
.145
.145
.145
.150
.151
.155
.157
.165
.165
.170
.170
.180
.175
.175
.175
.175
.176
!.27% Slope
increment was 6 min (for 9-15 mi:
rere 5 min for remainder of 120 m
at 123 min, final increment was
Herbicide Losses (mg)
Sediment
Atrazine
0.00
5.33
4.76
4.45
4.35
3.13
2.84
2.35
2.01
1.44
1.28
1.00
1.01
1.21
1.28
1.39
1.73
3.30
3.94
4.53
3.74
0.96
0.77
DCBN
0.00
5.18
5.84
5.58
2.68
4.13
1.90
0.41
0.49
0.45
0.36
0.23
0.35
0.87
1.00
0.99
1.53
4.33
5.13
4.32
2.68
0.09
0.07
Water
Atrazine
0.00
18.29
17.94
25.02
8.87
8.52
10.17
14.37
12.98
7.44
7.71
3.84
3.89
4.09
4.91
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
DCBN
0.00
33.20
25.76
25.22
36.92
22.90
27.31
21.56
18.78
14.87
13.43
7.68
7.78
8.18
8.23
8.43
8.52
8.92
8.67
8.67
7.80
4.34
3.47
(Runoff  stopped)
                                     86

-------
Gulfcoast
Site  #5, Plot  #2:  Red Bay Soil Type,  2.5%  Slope
Mobile, Alabama

    Plot Size	 1.83 m x 10.7 m
                                               (6.00 ft x 35.0 ft)
    Application Rate:
      Casoron  (50% dichlobenil                 13.4 kg/ha (12.0 Ib/A)
        Total Casoron applied                  27.2 g
        Total Dichlobenil (DCBN) applied       13.6 g (6.7 kg/ha)
      Aatrex (80% atrazine)                    4.21 kg/ha (3.76 Ib/A)
        Total Aatrex                           8.53 g
        Total Atrazine                         6.48 g (3.22 kg/ha)
About 753 gallons of water was applied over 120 minutes.  Runoff began
at 6 minutess samples were collected at specified time intervals during
rainfall and after the rainfall had stopped (120 min); runoff ended at
123 minutes.
    Results:
    1.  Total applied rainfall                 14.6 cm (5.75 in.)
        Total runoff (calculated)              10.5 cm (4.13 in.)
       ' Total sediment runoff  (calculated)     18.1 kg (39.9 Ib.)
    2.  Sediment runoff
        Sediment (SERL)                        8.95 x 103 kg/ha (3.99 T/A)
                                                        4
        Sediment and sandy (USDA)              1.52 x 10  kg/ha (6.79 T/A)
    3.  Atrazine recovered
        Total in sediment                      125 mg
        Total in water runoff                  739 mg
        Total recovered                        864 mg
    4.  Atrazine loss (% of applied)
        In sediment                            1.93%
        In water runoff                        11.4%
        Total                                  13.3%

                                    87

-------
5.  Dichlobenil recovered
    Total in sediment                      317 mg
                                                    3
    Total in water runoff                  1.04 x 10  mg
                                                    3
    Total recovered                        1.35 x 10  mg
6.  Dichlobenil loss (% of applied)
    In sediment                            2.33%
    In water runoff                        7.61%
    Total                                  9.94%
                                 88

-------
                   INCREMENTAL SOIL, WATER, AND HERBICIDE LOSS IN SEDIMENT AND WATER
                                         (English and Metric Units)
                             (Beginning with minute 6, first increment = 4 min,
                           subsequent increments = 5 min, final increment = 3 min)

                                             Red Bay, Site #5
Minute
6
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
123
Soil
T/A
.000
.164
.266
.251
.231
.199
.201
.194
.193
.193
.192
.167
.160
.160
.156
.137
.139
.144
.137
.128
.133
.151
.163
.135
Losses
kg/ha
0
368
596
563
518
446
451
435
433
433
430
374
359
359
350
307
312
323
307
287
298
338
365
303
Water
Losses
in. cm
. 000 . 000
. 080 . 203
.157 .399
.168 .427
.173 .439
.163 .414
.168 .427
.175 .444
.179 .455
.180 .457
.180 .457
.182 .462
.192 .488
.194 .493
.190 .483
.185 .470
.189 .480
.195 .495
.193 .490
.190 .483
.194 .493
.195 .495
.200 .508
.192 .488
(Runoff stopped)
Herbicide Losses
Ib/acre
Sediment
Atrazine
.000
.008
.004
.002
.002
.002
.004
.003
.003
.003
.003
.003
.003
.003
.003
.002
.002
.002
.001
.000
.000
.000
.000
.000

DCBN
.000
.019
.017
.014
.011
.008
.008
.007
.006
.006
.006
.005
.004
.004
.004
.003
.003
.002
.002
.002
.002
.002
.002
.002

Water
Atrazine
.000
.044
.053
.034
.026
.015
.009
.001
.012
.009
.008
.008
.008
.008
.008
.003
.012
.013
.010
.008
.008
.009
.005
.004

DCBN
.000
.020
.036
.029
.027
.015
.017
.032
.031
.029
.027
.018
.017
.019
.021
1,020
.018
.017
.017
.017
.014
.013
.010
.008


Sediment
kg/ha


Water
Atrazine DCBN Atrazine
.000
.009
.004
.002
.002
.002
.004
.003
.002
.003
.003
.003
.003
.003
.003
.002
.002
.002
.001
.000
.000
.000
.000
.000

000
021
019
016
012
009
009
008
007
007
007
006
004
004
004
003
003
002
002
002
002
002
002
002

.000
.049
.059
.038
.029
.017
.010
.012
.013
.010
.009
.009
.009
.009
.009
.003
.013
.015
.011
.009
.009
.010
.006
.004



DCBN
.000
.022
.040
.033
.030
.017
.019
.036
.035
.033
.030
.020
.019
.021
.024
.022
.020
.019
.019
.019
.016
.015
.011
.009

CO
VO

-------
Gulfcoast
Site #5, Plot #2:  Red Bay> Soil Type, 2.5% Slope
                                                   Time Period Losses
Note:  Runoff started at 6 min; first increment was 4 min (for 6-10 min
       period);  following increments were 5 min for remainder of 120 min
       rainfall; because runoff ended at 123 min,  final increment was
       3 min.
Time (min)   Soil and Water Losses
Herbicide Losses (mg)
                                         Sediment
               Water
Ib
6
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
123
0.000
1.635
2.655
2.510
2.306
1.
2.
1.
1.
1.
1.
1.
1.
1.
1.
1.
1.
1.
1.
1.
1.
1.
1.
1.
(Ru
990
007
938
929
928
920
665
601
602
560
365
393
440
371
279
333
514
630
354
noff stc
in.
.000
.080
.157
.168
.173
.163
.168
.175
.179
.180
.180
.182
.192
.194
.190
.185
.189
.195
.193
.190
.194
.195
.200
.192
>pped)
Atrazine DCBN
0.
17.
8.
5.
4.
4.
8.
7.
7.
7.
7.
6.
5.
6.
6.
4.
4.
3.
2.
0.
0.
0.
0.
0.

000
852
157
605
291
554
065
757
791
835
835
669
174
181
015
858
869
852
773
996
642
757
813
665

0.
44.
38.
31.
24.
17.
17.
15.
14.
14.
14.
10.
9.
9.
9.
7.
6.
5.
4.
4.
4.
4.
4.
3.

000
032
567
208
349
301
786
884
529
514
450
705
877
931
695
195
386
094
787
571
500
010
023
540

Atrazine
0.
99.
121.
76.
58.
34.
19.
26.
26.
19.
17.
18.
19.
19.
18.
7.
26.
28.
22.
18.
19.
19.
11.
9.

000
852
168
305
321
040
967
015
611
624
840
038
028
226
830
334
263
990
993
830
226
325
892
515

DCBN
0.000
45.
82.
66.
61.
34.
38.
72.
70.
66.
52.
41.
38.
44.
47.
45.
41.
38.
38.
37.
30.
28.
21.
19.

,791
,348
645
642
037
549
839
958
003
435
427
056
099
075
836
178
650
254
660
724
990
801
028

                                   90

-------
Gulfcoast
Site #6, Plot #2:  Bowie Soil Type, 3.6% Slope
Mobile, Alabama

    Plot Size	 1.83 m x 10.7 m
                                             (6.00 ft x 35.0 ft)
    Application Rate:
      Casoron  (50% dichlobenil)              13.4 kg/ha (12.0 Ib/A)
        Total Casoron applied                27.2 g
        Total Dichlobenil  (DCBN) applied     13.6 g (6.97 kg/ha)
      Aatrex (80% atrazine)                  2.11 kg/ha (1.88 Ib/A)
        Total Aatrex                         4.26 g
        Total Atrazine                       3.24 g (1.66 kg/ha)
About 720 gal. of water was applied over 120 minutes.  Runoff began at
3 minutes, samples were collected  at  specified time intervals during
rainfall and after the rainfall had stopped  (120 min); runoff ended at
124 minutes.
    Results:
    1.  Total applied rainfall               13.9 cm  (5.47 in.)
        Total runoff  (calculated)            10.2 cm  (4.02 in.)
        Total sediment runoff -,(calculated)   31.2 kg  (68.7 Ib)
    2.  Sediment runoff
        Sediment  (SERL)                      1.54 x 104 kg/ha (6.87 T/A)
        Sediment and sand  (USDA)             2.55 x 104 kg/ha (11.4 T/A)
    3.  Atrazine recovered
        Total in sediment                    70.2 mg
        Total in water runoff                334.0 mg
        Total recovered                      404.0 mg
    4.  Atrazine loss  (% of applied)
        In sediment                          2.17%
        In water runoff                      10.3%
        Total                                12.5%

                                    91

-------
5.   Dichlobenil recovered
    Total in sediment                    404 mg
    Total in water runoff                816 mg
                                                  3
    Total recovered                      1.22 x 10  mg
6.   Dichlobenil loss (% of applied)
    In sediment                          2.97%
    In water runoff                      5.99%
    Total                                8.96%
                                92

-------
INCREMENTAL SOIL, WATER, AND HERBICIDE LOSS IN SEDIMENT AND WATER
                      (English and Metric Units)
          (Beginning with minute 3, first increment = 7 min,
       subsequent increments = 5 min, final increment = 4 min)

                         Malbis, Site #6
Minute
3
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
124
Soil Losses
T/a kg/ha
.000 0
.456 1022
.434 973
.348 780
.422 946
.401 899
.344 771
.337 755
.334 749
.336 753
.333 746
.311 697
.300 672
.252 565
.238 534
.222 498
.226 507
.235 527
.234 525
.239 536
.247 554
.210 471
.198 444
.220 493
Water
Losses
in.
.000 .
.131 .
.171 .
.172 .
.174 .
.165 .
.164 .
.168 .
.168 .
.180 .
.180 .
.182 .
.178 .
.181 .
.179 .
.175 .
.175 .
.176 .
.178 .
.180 .
.180 .
.180 .
.180 .
.177 .
(Runoff stopped)
cm
000
333
434
437
442
419
417
427
427
457
457
462
452
460
455
444
444
447
452
457
457
457
457
450

Herbicide Losses
Ib/acre
Sediment
Atrazine
.000
.007
.003
.002
.002
.002
.001
.000
.000
.000
.000
.000
.000
.001
.001
.001
.001
.001
.001
.002
.002
.002
.002
.002

DCBN
.000
.045
.020
.012
.010
.009
.004
.001
.001
.006
.006
.007
.007
.006
.005
.005
.005
.005
.005
.005
.005
.004
.004
.003

Water
Atrazine
.000
.030
.015
.010
.008
.007
.007
.007
.004
.004
.004
.004
.004
.004
.004
.004
.004
.004
.004
.004
.004
.004
.004
.004


DCBN
.000
.033
.026
.020
.023
.019
.016
.015
.015
.016
.020
.020
.015
.016
.016
.011
.011
.011
.012
.016
.012
.008
.007
.004

kg/ha
Sediment
Atrazine
.000
.008
.003
.002
.002
.002
.001
.000
.000
.000
.000
.000
.000
.001
.001
.001
.001
.001
.001
.002
.002
.002
.002
.002

Water
DCBN Atrazine
.000
.050
.022
.013
.011
.010
.004
.001
.001
.007
.007
.008
.008
.007
.006
.006
.006
.006
.006
.006
.006
.004
.004
.003

.000
.034
.017
.011
.009
.008
.008
.008
.004
.004
.004
.004
.004
.004
.004
.004
.004
.004
.004
.004
.004
.004
.004
.004


DCBN
.000
.037
.029
.022
.026
.021
.018
.017
.017
.018
.022
.022
.017
.018
.018
.012
.012
.012
.013
.018
.013
.009
.008
.004


-------
Gulfcoast
    Time Period Losses
Site #6, Plot #2:  Bowie Soil Type,  3.6% Slope
Note:  Runoff started at 3 min; first increment was 7 min (for 3-10 min
       period);  following increments were 5 min for remainder of 120 min
       rainfall; because runoff ended at 124 min,  final increment was
       4 min.
Time (min)   Soil and Water Losses
Herbicide Losses (mg)
Soil

3
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
124

0
4
4
3
4
4
3
3
3
3
3
3
2
2
2
2
2
2
2
2
2
2
1
2
lb_
.000
.564
.340
.476
.217
.012
.435
.369
.337
.360
.327
.105
.993
.522
.375
.215
.263
.346
.344
.390
.471
.100
.975
.197
(Runoff
Water
in.
.000
.131
.171
.172
.174
.165
.164
.168
.168
.180
.180
.182
.178
.181
.179
.175
.175
.176
.178
.180
.180
.180
.180
.177
stopped)
Sediment
Atrazine
0.
16.
6.
4.
3.
4.
1.
0.
0.
0.
0.
0.
0.
1.
1.
1.
1.
2.
3.
3.
3.
4.
4.
3.

000
302
752
895
743
152
376
000
000
000
000
000
000
256
492
805
733
983
261
575
465
760
958
689

DCBN
0.
102.
44.
27.
23.
20.
8.
2.
2.
12.
13.
16.
15.
12.
12.
11.
11.
10.
10.
10.
11.
9.
8.
6.

000
003
364
141
588
488
024
600
994
505
962
340
071
687
269
545
507
538
289
505
038
135
460
851

Water
Atrazine
0.
68.
33.
23.
17.
16.
16.
16.
8.
8.
8.
9.
8.
8.
8.
8.
8.
8.
8.
8.
8.
8.
8.
8.

000
387
868
860
245
301
204
600
300
920
920
045
795
970
870
670
670
695
759
895
920
920
920
826

DCBN
0
74
57
46
51
42
35
33
33
35
44
45
35
35
35
26
24
26
28
35
26
17
16
8

.000
.235
.975
.035
.732
.388
.628
.200
.200
.680
.595
.220
.185
.679
.481
.015
.281
.090
.149
.581
.760
.840
.056
.826

                                   94

-------
Gulfcoast
Site #7, Plot #1:  Bowie Soil Type, 5.7%  Slope
Mobile, Alabama

    Plot Size	  1.83 m x 10.7 m
                                              (6.00 ft x  35.0 ft)
    Application Rate:
      Casoron (50% dichlobenil)               13.4 kg/ha  (12.0 Ib/A)
        Total Casoron applied                 27.2 g
        Total Dichlobenil  (DCBN) applied      13.6 g (6.7 kg/ha)
      Aatrex (80% atrazine)                   4.21 kg/ha  (3.76 Ib/A)
        Total Aatrex                          8.53 g
        Total Atrazine                        6.48 g (3.32 kg/ha)
About 700 gal. of water was applied over  120  minutes.  Runoff began at
6 minutes, samples were collected at specified  time intervals during
rainfall and after the rainfall had stopped  (120 min); runoff ended at
122 minutes.
    Results:
    1.  Total applied rainfall                13.5 cm (5.32 in.)
        Total runoff  (calculated)             9.37 cm (3.69 in.)
        Total sediment runoff  (calculated)    30.9 kg (68.1 Ib)
    2.  Sediment runoff
        Sediment (SERL)                       1.53 x 10  kg/ha (6.81 T/A)
        Sediment and sandy  (USDA)             3.07 x 10  kg/ha (13.7 T/A)
    3.  Atrazine recovered
        Total in sediment                     197 mg
        Total in water runoff                 463 mg
        Total recovered                       660 mg
    4.  Atrazine Loss (% of applied)
        In sediment                           3.04%
        In water runoff                       7.14%
        Total                                 10.2%

                                   95

-------
5.  Dichlobenil recovered
    Total in sediment                    347 mg
    Total in water runoff                281 mg
    Total recovered                      628 mg
6.  Dichlobenil loss (% of applied)
    In sediment                          2.55%
    In water runoff                      2.07%
    Total                                4.62%
                                96

-------
INCREMENTAL SOIL, WATER, AND HERBICIDE LOSS IN SEDIMENT AND WATER
                      (English and Metric Units)
          (Beginning with minute 6, first increment = 4 min,
       subsequent increments = 5 min, final increment = 2 min)

                         Malbis, Site #7
Minute
6
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
122
Soil Losses
T/A kg/ha
.000 0
.238 534
.342 767
.371 832
.347 778
.326 731
.268 601
.311 697
.307 688
.265 594
.263 590
.292 655
.302 677
.365 818
.364 816
.295 661
.280 628
.243 545
.254 569
.294 659
.290 650
.266 596
.266 596
.264 592
Water
Losses
in.
.000 .
.071 .
.126 .
.143 .
.150 .
.150 .
.152 .
.162 .
.165 .
.170 .
.170 .
.166 .
.165 .
.172 .
.172 .
.174 .
.175 .
.170 .
.170 .
.170 .
.170 .
.172 .
.172 .
.172 .
(Runoff stopped)
cm
000
180
320
363
381
381
386
411
419
432
432
422
419
437
437
442
444
432
432
432
432
437
437
437

Herbicide Losses
Ib/acre
Sediment
Atrazine
.000
.006
.006
.003
.003
.003
.002
.002
.002
.005
.006
.007
.007
.002
.002
.002
.002
.002
.002
.003
.003
.005
.005
.006

DCBN
.000
.015
.020
.012
.010
.010
.007
.008
.008
.008
.007
.005
.005
.004
.004
.004
.004
.004
.004
.003
.003
.002
.002
.002

Water
Atrazine
.000
.009
.022
.016
.017
.013
.012
.012
.011
.011
.011
.011
.007
.008
.008
.008
.005
.004
.004
.004
.004
.004
.004
.004


DCBN
.000
.009
.017
.012
.011
.008
.007
.007
.007
.007
.007
.007
.007
.005
.004
.004
.004
.004
.004
.000
.000
.000
.000
.000

kg/ha
Sediment
Atrazine
.000
.006
.007
.003
.003
.003
.002
.002
.002
.006
.007
.008
.008
.002
.002
.002
.002
.002
.002
.003
.003
.006
.006
.007

Water
DCBN Atrazine
.000
.007
.022
.013
.011
.011
.008
.008
.009
.009
.008
.006
.006
.004
.004
.004
.004
.004
.004
.003
.003
.002
.002
.002

.000
.010
.025
.018
.019
.015
.013
.013
.012
.012
.012
.012
.008
.009
.009
.009
.006
.004
.004
.004
.004
.004
.004
.004

DCBN
.000
.007
.019
.013
.012
.009
.008
.008
.008
.008
.008
.008
.008
.006
.004
.004
.004
.004
.004
.000
.000
.000
.000
.000


-------
Gulfcoast
    Time Period Losses
Site #7, Plot #1:  Bowie Soil Type,  5.7% Slope
Note:  Runoff  started  at  6  min;  first increment was 4 min  (for  6-10  min
       period);  following increments were 5 min for remainder of  120 min
       rainfall; because  runoff  ended at 122 min, final increment was
       2 min.
Time  (min)    Soil  and  Water Losses
Herbicide Losses  (mg)
Soil
Ib
6
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
122
0
2
3
3
3
3
2
3
3
2
2
2
3
3
3
2
2
2
2
2
2
2
2
2
.000
.375
.418
.705
.472
.256
.683
.108
.070
.645
.625
.924
.020
.654
.635
.945
.800
.427
.543
.939
.895
.659
.655
.635
(Runoff
Water
in.
.000
.071
.126
.143
.150
.150
.152
.162
.165
.170
.170
.166
.165
.172
.172
.174
.175
.170
.170
.170
.170
.172
.172
.172
stopped)
Sediment
Atrazine
0.
12.
12.
6.
6.
5.
5.
4.
5.
12.
14.
16.
15.
4.
4.
4.
5.
5.
5.
6.
6.
11.
11.
12.

000
701
944
227
083
799
461
954
010
328
180
866
345
406
450
960
184
286
426
755
960
065
920
666

DCBN
0
33
45
27
23
23
16
17
18
17
17
11
10
8
8
9
9
8
8
7
6
5
.000
.570
.009
.910
.858
.405
.380
.670
.650
.944
.040
.305
.960
.811
.900
.375
.504
.275
.313
.066
.960
.623
5.420
5

.194

Wate:
Atrazine
0.
21.
49.
35.
37.
30.
27.
24.
24.
25.
25.
24.
16.
17.
17.
17.
10.
8.
8.
8.
000
057
453
562
680
145
187
154
525
270
270
674
350
095
095
295
405
425
425
425
8.425
8.525
8.550
8.525


c
DC
0.
14.
38.
26.
24.
18.
15.
16.
9.
15.
16.
16.
16.
10.
8.
8.
8.
8.
8.
0.
0.
0.
0.
0.

BN
000
623
800
925
117
086
106
103
810
111
845
449
350
259
550
646
670
425
425
000
,000
,000
,000
000

                                     98
                                          U.S. GOVERNMENT PRINTING OFFICE: 1974—546-319:384

-------
 SELECTED WATER
 RESOURCES ABSTRACTS
 INPUT TRANSACTION FORM
Rff&tttfa
J, Accession No.
                  w
 4. Title

HERBICIDE RUNOFF FROM FOUR COASTAL PIAIN SOIL TYPES,
 7. Authors) BAILEY,  G. W.,  BARNETT,  A.  P., PAYNE, W. R. JR.,
           AND SMITH, C. N.
 9. Organization

SOUTHEAST ENVIRONMENTAL RESEARCH LABORATORY
ATHENS, GEORGIA 30601
                  10.  Project No.
                  11.  Contract/Grant No.


                  13.
 IS.  Supplementary Notes

    Environmental Protection Agency report number, EPA-660/2-74-017, April 1974.
 IS.  Abstract
     The movement of two herbicides  in runoff and on sediment were studied as examples
of pesticides in general use.   Gas chromatography was used to determine the losses of
atrazine (2-chloro^4-ethylamino-6-isopropylamino-s-triazine)  and dichlobenil
(2,6-dichlorobenzonitrile)  from fallow plots  on four Coastal  Plain soil types
following the application of about 13  cm (5 in.) of rainfall  in 2 hours.
     The herbicides, as wettable powders,  were surface-applied and incorporated.
Simulated high intensity  (a 100-year frequency storm) rainfall was started 1 hour
after application.
     Significant amounts of both compounds were transported.   The percent loss was
greater in all cases for atrazine, but because more dichlobenil was applied, its losses
were greater on an absolute basis.   Some of the herbicide in  the sediment _may have been
transported as discrete particles rather than as an adsorbate.

     The greatest combined  (runoff plus sediment) losses of atrazine in all soils and
of dichlobenil in two  soils occurred during the first 40-50 minutes of runoff.  During
this time, the absolute amount  of both herbicides was greater in runoff, but the
concentrations were greater in  the sediment.   The preferential loss of certain clay-
sized materials during the  first 50  minutes of runoff may explain the high herbicide
concentration in sediment relative to  later times. _
 17a. Descriptors
*Runoff, *Herbicides, *Simulated rainfall,  *Soil types,  Coastal Plains,  Gas
 Chromatography
 lib. Identifiers
*Pesticide movement, *Preferential  herbicide loss,  Atrazine, Dichlobenil, Fallow plots.
 l~c. COWRRField& Group  Q5B
18. Availability PlpB
m Seeuti
fp»Sf
Abstractor
George W. Bailey
SMEWS?
*»&
2; »e a?
Pages
22 Price
Send To:
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON, D. C. 2O24O
| Institution EPA, Southeast Environmental Res. Lao.

-------
      UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
               SOUTHEAST ENVIRONMENTAL RESEARCH LABORATORY
                          ATHENS, GEORGIA 30601
                 EPA Report 660/2-74-017 ERRATA SHEET

     Tables Number 5 through 9 are in error.  The attached
Tables (5-9) should replace the Tables 5-9 in the report at
pages 34, 35, 36, and 56, respectively.
     Page 42, line 11 should read: stabilizing at a concentration
of 0,1 ppm near the end.
     Any questions regarding the report should be directed to
Dr. George W. Bailey, telephone number 404/546-3149.

-------
Table 5.  HERBICIDE CONCENTRATION (ppm) IN RUNOFF WATER AND ON SEDIMENT




                          FROM DOTHAN, SITE 2
Time From
Onset of „ , .
„ . c , , Sediment
Rainfall,
Min
9
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
123
Atrazine DCBN
0.0
10.7
7.8
11.5
9.7
7.3
5.6
5.6
4.2
4.2
4.0
4.0
4.3
4.3
5.5
5.5
11.2
11.2
15.1
15.1
6.6
6.6
Negative
(Runoff
0.0
8.3
13.9
10.7
5.8
7.3
1.0
1.0
1.3
1.3
0.9
0.9
3.1
3.1
3.9
3.9
14.7
14.7
14.1
14.1
0.6
0.6
Negative
Stopped)
Water
Atrazine DCBN
0.00
0.3
0.4
0.3
0.1
0.1
0.2
0.2
0.1
0.1
0.05
0.05
Negative
0.05
0.1
Negative
Negative
Negative
Negative
Negative
Negative
Negative
Negative

0.00
0.6
0.4
0.5
0.4
0.4
0.3
0.3
0.2
0.2
0.1
0.1
0.1
0.1
0.1
Negative
Negative
Negative
Negative
Negative
Negative
Negative
Negative

                                   34

-------
Table 6.  HERBICIDE CONCENTRATION (ppm) IN RUNOFF WATER AND ON SEDIMENT
                         FROM RED BAY, SITE 5
Time From
Onset of
Rainfall,
Min
7
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
123
Sediment
Atrazine
0.0
10.8
6.1
5.7
3.8
7.3
9.0
8.9
8.9
9.0
9.0
8.5
8.5
8.5
8.5
7.7
7.7
4.5
4.4
1.0
1.7
1.1
1.1
1.1
(Runoff Stoppe

DCBN
0.0
37.1
32.5
23.2
23.5
17.5
20.1
16.6
16.6
16.6
16.6
13.6
13.6
13.7
13.7
10.1
10.1
7.7
7.7
7.5
7.4
5.5
5.4
6.5
id)
Water
Atrazine
0.0
2.1
1.3
0.5
0.6
0.3
0.3
0.3
0.3
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.3
0.3
0.2
0.2
0.2
0.2
0.1
0.1


DCBN
0.0
0.4
0.9
0.9
0.6
0.3
0.7
0.8
0.8
0.7
0.7
0.4
0.4
0.5
0.5
0.5
0.4
0.4
0.4
0.4
0.3
0.3
0.2
0.2

                                    35

-------
Table 7-  HERBICIDE CONCENTRATION  (ppm) IN RUNOFF WATER AND ON SEDIMENT




                     FROM MALBIS (BOWIE), SITE 6
Time Froi
Onset of
Rainfall
Min
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
124
Sediment
Atrazine
0.0
5.5
4.1
2.6
2.3
2.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
1.1
2.3
1.8
1.3
2.8
4.3
3.3
2.3
5.0
7.8
1.1
DCBN
0.0
27.4
17.7
16.5
11.1
12.0
0.8
1.7
2.7
8.2
13.7
11.6
4.4
11.1
12.8
11.5
10.2
9.9
9.5
9.7
10.0
9.6
9.1
5.5
Water
Atrazine
0.0
0.6
0.3
0.2
0.2
0.2
0.2
0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
DCBN
0.0
0.8
0.6
0.6
0.6
0.5
0.4
0.4
0.4
0.4
0.5
0.5
0.4
0.4
0.4
0.3
0.2
0.3
0.4
0.4
0.3
0.2
0.1
0.1
(Runoff Stopped)
                                     36

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Table 8.  HERBICIDE CONCENTRATION (ppm) IN RUNOFF WATER AND ON  SEDIMENT




                     FROM MALBIS (BOWIE), SITE 7
Time From
Onset of Sediment
Rainfall.
Min
6
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
122
Atrazine DCBN
0.0
9.2
4.7
3.7
4.1
4.4
4.3
3.6
3.6
11.9
11.9
11.2
11.2
2.7
2.7
4.0
4.1
4.7
4.7
5.3
5.3
9.9
9.9
13.5
(Runoff Stoi
0.0
17.5
20.5
15.0
15.9
16.0
12.9
13.4
13.4
14.3
14.3
8.0
8.2
5.4
5.4
7.4
7.5
7.2
7.2
5.3
5.3
4.5
4.5
3.7
>ped)
Water
Atrazine DCBN
0.00
1.0
0.6
0.5
0.4
0.4
0.3
0.3
0.3
0.3
0.3
0.3
0.2
0.2
0.2
0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1

0.00
0.3
0.6
0.3
0.3
0.2
0.2
0.2
0.1
0.2
0.2
0.2
0.2
0.1
0.1
0.1
0.1
0.1
0.1
Negative
Negative
Negative
Negative
Negative

                                    37

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Table 9.  PERCENT CUMULATIVE AND FRACTIONAL LOSS
       OF HERBICIDES ON DOTHAN, SITE 2
Time From
Onset of
Cumulative , %
Rainfall, Atrazine
Min.
9
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
123
Sediment
0
9
18
26
33
39
44
48
51
54
56
58
60
62
64
67
70
76
82
90
97
99
100
(Runoff stopped)
Water
0
13
25
43
49
55
62
72
81
86
91
94
97
99
100









Total
0
12
23
38
44
50
57
65
72
76
81
83
85
88
91
91
92
94
96
98
99
100
100

Dichlobenil
Sediment
0
11
23
34
40
49
53
54
55
56
56
57
57
60
62
64
66
75
86
94
100
100
100

Water
0
10
18
25
37
44
52
58
64
69
73
75
77
80
82
85
87
90
93
95
98
99
100

Total
0
10
19
27
37
44
52
58
63
67
70
73
75
75
77
82
88
88
92
95
98
99
100

Fractional Loss
in Sediment and
Water
Atrazine DCBN
0
0.77
0.66
0.87
0.39
0.34
0.38
0.49
0.44
0.26
0.26
0.14
0.14
0.15
0.18
0.04
0.05
0.09
0.11
0.13
0.08
0.03
0.02

0
0.28
0.23
0.23
0.29
0.20
0.21
0.16
0.14
0.11
0.10
0.06
0.06
0.07
0.07
0.07
0.07
0.10
0.10
0.09
0.08
0.03
0.03

                   56

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