Effect of Grass Buffer Zone Length in Reducing
the Pollution from Land Application Areas
S. C. Bingham, P. W. Westerman, M. R. Overcash
ASSOC. MEMBER
ASAE
MEMBER
ASAE
ABSTRACT
field study was conducted to determine the effect of
length of grass buffer zones in reducing pollutant
concentration in rainfall runoff from land application
areas. Evaluation of pollutant concentrations in runoff at
various distances downslope from an area where cagedlayer poultry manure was applied regularly indicated
that for the conditions of this experiment a buffer area
length to waste area length ratio of 1.0 was usually required to reduce concentrations to those measured in
runoff from a similar plot receiving no manure. Less buffer area would be needed if concentrations greater than
background conditions were acceptable.
A
INTRODUCTION
Land disposal of animal waste has long been recognized as an economical means of productively using manure
constituents and an efficient means of disposing of
animal waste. However, the nonpoint source pollution
potential of runoff from land application sites can be
large with high application rates unless control techniques are adequate. Grass buffer areas located between
the area receiving animal waste and the stream reduce
the concentration and mass entering the stream during
rainfall runoff events. The amount of land area required
for a land application system increases as the buffer area
size increases. Thus, the cost of a buffer zone can be a
major factor in the cost-benefit analysis of land application waste treatment.
The objective of this research was to determine experimentally the effectiveness of several lengths of grass
buffer zones in improving the water quality of surface
runoff from land application areas.
REVIEW OF LITERATURE
Buffer strips are used to control several different types
of pollution. Below land application areas, a buffer strip
reduces the nutrient load in runoff. A vegetated filter
strip is an effective feedlot control practice for improving
Article was submitted for publication in May 1979; reviewed and approved for publication by the Soil and Water Division of ASAE in
September 1979.
Paper No. 5920 of the Journal series of the North Carolina
Agricultural Research Service, Raleigh, NC.
The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service of the products named, nor criticism of similar ones not mentioned.
The authors are: S. C. BINGHAM, Former Graduate Student and
presently Civil Engineer, USDA-Soil Conservation Service, Rutherfordton,NC; P. W. WESTERMAN, and M. R. OVERCASH,
Associate Professors, Biological and Agricultural Engineering Dept.,
North Carolina State University, Raleigh.
Acknowledgment: Research was supported by the North Carolina
Agricultural Research Service and the U.S Environmental Protection
Agency's R. S. Kerr Environmental Research Laboratory, Ada, OK.
330
MEMBER
ASAE
the water quality related to feedlot runoff. Vegetated
filter strips are also used to control sediment on
agricultural lands and to remove pesticides from surface
runoff.
Doyle et al. (1977). using 45-m and 7-m waste area
lengths on a silt loam soil for a forest and grass buffer
zone study, respectively, applied 850 kg N/ha (90 t/ha of
dairy manure) and found that a 3.8-m forest buffer
length and a 4.0-m grass buffer length were useful in improving the water quality of manure-polluted runoff
under the experimental conditions. Thompson (1977)
measured the nutrients in winter runoff from three surface conditions on a sandy loam soil. With a 24-m long
waste area that received approximately 600 kg N/ha (63
t/ha of dairy manure), he found significant reductions in
concentrations with distance downslope for buffer strip
lengths of 12.2 and 36.6 m.
Edwards et al. (1971), Dickey et al. (1977), and Swanson et al. (1975) found that a 500-m heavily grassed
waterway, vegetative filters, and a serpentine waterway,
respectively, permitted highly polluted initial runoff
from barnlots and feedlots to be infiltrated into the soil
and diluted by runoff from outside areas. Sievers et al.
(1975) found that the combined effects of passing lagoon
effluent over a 259-m grass terrace and adding dilution
water from cropland reduced the concentration of most
of the pollutants. Light (1972) described a grass filtration
bed for disposal of milking center waste of which one advantage was removal of nutrients contained in the
wastewater.
Many researchers have found that control devices that
include vegetated buffer strips reduced or even
eliminated sediment and nutrient losses. Stewart et al.
(1975) proposed vegetated filter strips since the strips
trap sediments near their point or origin, but they admitted that more research is needed regarding their design
for optimum trapping efficiency and particle size selectivity. Hayes and Barfield (1977) presented a nonsteadystate model for determining the sediment filtration of an
artificial grass filter under various flow rates. To control
erosion and to protect the edge of fields that are used as
turn rows or travel lanes for farm machinery, the Soil
Conservation Service (1975) recommends a field border
practice that is a strip of perennial vegetation at the edge
of a field. Fitzsimmons et al. (1978) evaluated the effectiveness of sediment removal devices for removing sediment, phosphorus, and other materials from surface
return flows from irrigation. Karr and Schlosser (1977)
reviewed the literature on the possible use of near-stream
vegetation to reduce the transport of sediments and
nutrients from terrestrial to aquatic environments.
Asmussen et al. (1977) reported that a 24.4-m grassed
waterway was effective in reducing the herbicide load in
surface runoff from corn plots approximately 9 m in
length treated with 2,4-D. The total loss (on sediment
© 1980 American Society of Agricultural Engineers 0001-2351/80/2302-0330$02.00
TRANSACTIONS of the ASAE—1980
TABLE 1. BUFFER AREA LENGTH/
WASTE AREA LENGTH RATIO FOR
R U N O F F COLLECTED AT DOWNSLOPE
SIDE OF THE VARIOUS TERRACES
Ratio of buffer area length t o
waste area length
TIPPING
BUCKET
I C^BARREL
FIG. 1 Schematic of waste area and buffer zone system
during fall and winter.
and in solution) of the applied 2,4-D from the plot in dry
and wet conditions was 2.5 and 10.3 percent, respectively. Of the 2,4-D lost from the plots and entering the
24.4-m waterway, approximately 30 percent reached the
end of the waterway regardless of antecedent soil
moisture.
Among these articles are a number of general recommendations on the use of vegetative buffers and some
measurements of water quality. However, more data is
needed relating buffer zone length to surface runoff
water quality in order to design buffer zones to meet
water quality goals, and to evaluate cost effectiveness of
buffer zones.
Terrace
For fall a n d winter
For spring
1
2
3
4
5
6
7
8
9
0.3
1.6
Control
0.2
1.4
2.6
0.0
1.0
2.0
0.3
1.6
Control
0.2
0.5
0.75
0.0
1.0
2.0
EXPERIMENTAL DESIGN AND PROCEDURES
The field study consisted of measuring rainfall runoff
quantity and pollutant concentrations at various
distances downslope from an area where caged-layer
poultry wastes were applied regularly. Runoff was collected, sampled, and then redistributed at each sampling
distance (Fig. 1). Dimensions of the land application
areas and nine terraces and the sampler and drainage
system placement for the fall and winter are shown in
Fig. 1.
The field study was changed somewhat during the
spring to examine intermediate sampling distances. The
changes are found in Table 1. Two of the long buffer
lengths were changed to shorter lengths by adding two
more waste areas.
Rainfall runoff was collected in a gutter at the end of
each terrace, passed through a tipping-bucket sampler,
and redistributed through a slightly tilted, slotted gutter
(Fig. 2); or, after runoff passed the last sampling point in
each terrace series, it was routed through a tile system
away from the plots. Each terrace was bordered by a
ditch. The ditches were 40 cm wide and 25 cm deep.
Runoff could not enter the top terrace from upslope or
run off the sides of the terraces because of a 25-cm berm
DISTRIBUTION GUTTER
FIG. 2 Schematic of flow collector and distributor. (Flow-split routes approximately 1/25 of
volume from each tip to the barrel).
1980—TRANSACTIONS of the ASAE
331
TABLE 2. AMOUNT OF MATERIAL APPLIED TO
THE WASTE AREAS AS DETERMINED BY
PLATE COLLECTION
Date
TKN
T-P
COD
CI
8-23-77
9-29-77
10-12-77
11-2-77
11-21-77
12-15-77
1-5-78
1-27-78
4-21-78
5-5-78
5-17-78
Total
158
78
35
53
31
70
28
69
80
60
60
722
31
23
8
12
6
19
9
19
24
22
24
197
1,833
26
11
5
5
4
9
4
7
14
14
12
111
923
384
480
259
991
376
847
1,028
816
741
8,678
TOC
194
155
47
112
47
113
36
117
140
145
167
1,273
around each terrace. Drainage water between terraces
was diverted to nonperforated tile drains.
The soil in the buffer zone site is in the Cecil series, a
common soil in the Piedmont subregion of the Southeast.
Overcash et al. (1976) found that surface samples of the
upper 10 cm were in the clay loam textural class. Subsurface samples were in the clay textural class. When the
runoff plots were graded to a uniform slope of 6 to 8 percent, the soil horizons were disturbed at the lower end of
the plots. These disturbances could affect the infiltration
characteristics of the soil.
The plots were seeded with a mixture of reed
canarygrass, redtop, and tall fescue in 1974 (Overcash et
al., 1976). Fescue has become the dominant grass since
initial seeding, with scattered patches of reed
canarygrass, redtop, and common bermudagrass.
The poultry waste from the alley of a caged-layer house
was stored in a side-flail manure spreader for 1 or 2 days
until a sample could be analyzed to determine the
nitrogen content. The poultry waste was applied by a
lawn spreader with flow control.
Availability of most nutrients for runoff transport
decreases with time after waste application. To determine buffer zone effectiveness during the critical period
soon after waste application, several applications were
made. Initially, nutrients on the soil surface and grass
were measured and summed to determine the total
nutrient availability on the plot. However, of the waste
applied to the soil-grass complex, nearly 100 percent was
on the grass. Therefore, grass samples were used in
determining the amount of waste to apply and the soil
samples were used as a check on nitrogen buildup on the
soil surface. The objective of the grass and soil analysis
was to determine the application rate of nitrogen to
maintain a uniform load of 100 kg/ha total Kjeldahl
nitrogen (TKN) on the vegetation. Initially, 158 kg
TKN/ha was applied and depending on the number of
rainfall events, condition of vegetation, and relative
buildup of soil nitrogen 30 to 75 kg TKN/ha was applied
every 2 to 3 weeks depending on availability of wastes,
weather, and schedule of field personnel (Table 2). The
amount of waste applied was measured by placing 50-by50-cm plates at 3 random sections on a terrace divided
into 100 equal sections. The measured amount of
nutrients applied probably represents a conservative
estimate since volatilization, sampling loss, and
spreading loss decreased the amount of nutrients in the
sample.
The terraces were divided into 100 sections 1.2 m by
0.87, 1.0, 1.01, or 1.3 m, depending on the particular
332
terrace by placing wooden stakes along the edges of the
terrace. Randon numbers were used to determine from
which sections the grass and soil samples would be
taken. The first sample in a section was taken in the upper left corner of the plot, and, if that same section was
chosen at a later date, the next sample was taken at a
position clockwise from the first.
The grass sample at each sampling point was taken
with a 23-by-23-cm template. There were three sampling
points in each composite sample and two composite
samples per terrace both before and after waste was applied. The grass and loose organic material (dead vegetation, etc.) on the soil surface were put in plastic bags and
taken to the laboratory for analysis. The grass was washed by adding 3 L of deionized water to the plastic bag
and shaking the bag 5 min at approximately 200 excursion/min. This was repeated three times to obtain 9 L of
wash water. Samples were taken by stirring the wash
water and dipping the samples from the center of the
container.
Three random 1.9-cm diameter cores of the upper 2
cm of soil were taken at the three sampling points. A
preliminary experiment revealed that the 2-cm depth was
more effective than a 5-cm depth in detecting nutrient
levels near the soil surface. Several soil samples of the
surface 2 and 5 cm were taken before and after waste was
applied and on the fourth and seventh day after waste
was applied. The concentration of TKN was higher in the
surface 2 cm than in the surface 5 cm. Increasing the
sampling depth resulted essentially in a constant amount
of waste being mixed with a greater amount of soil. Even
though the 2-cm deep sample was more sensitive to
nutrient additions to the soil surface, small deviations
from the 2-cm sampling depth may also result in large errors in soil nitrogen measurements. Since depths could
be sampled only to plus or minus 1/2 cm and the antecedent moisture content of the soil affected the soil sampling procedure, it was concluded that soil sampling
could be used only as a check for a relative buildup of soil
TKN.
Below each terrace, a composite runoff volume was obtained by collecting approximately 200 mL from each tip
of the 5-L tipping buckets. For runoff collection, barrels
208 L in volume were partially buried at each sampling
station and a 114-L plastic barrel was placed inside each
large barrel. After each rainfall event, barrels containing
runoff were stirred thoroughly before two composite
samples were taken from the middle of the barrel. Composite samples were taken to the laboratory where they
were refrigerated or frozen until the laboratory analysis
was complete. Pollution parameters measured in water
samples included TKN, total phosphorus (T-P),
chemical oxygen demand (COD), total organic carbon
(TOC), chloride (CI), ammonium nitrogen (NH4-N), orthophosphate phosphorus (O-P), and nitrate nitrogen
(N0 3 -N). Procedures for all soil, grass, and water
analyses are reported by Bingham (1978).
Runoff volumes were determined by recording the
number of bucket tips on a mechanical counter. Runoff
volumes were sometimes difficult to quantify, because
the tipping bucket occasionally malfunctioned. Still,
runoff volumes were recorded on part of the terraces for
most runoff events.
RESULTS AND DISCUSSION
During the experiment, the goal was to keep the
TRANSACTIONS of the ASAE—1980
Dot«
rr
Days after
waste applied
RAINFALL, DAYS AFTER
cm
WASTE
APPLIED
0-26-77
5.46
15
DATE
Number of
previous
events
1
0—0
NUMBER OF
PREVIOUS
EVENTS
1
10-26-77
5.46
15
#—^11 -06-77
4.37
5
1
•—•
1-06-77
4.37
5
o
2.56
4
1
o—o
1-08-78
2.56
4
1
D 1- 14-78
4.32
9
2
0—0
A
Rainfall
cm
o
1-08-78
1
1
•
•
1-14-78
4.32
9
2
D
1
•
•
1-17-78
2.08
13
3
•—•
1-17-78
2.08
13
3
K 1-19-78
4.42
15
4
X
X
1-19-78
4.42
15
4
•—*
1-25-78
2.78
21
5
6 4-26-78
14.00
5
0
4.34
3
0
1 X
\ \
•
•
1-25-78
2.78
21
5
^
^ 4-26-78
14.00
5
0
4.34
3
0
\vi A
*
5-08-78
A
u—*
5-08-78
/
/
/
Ly
P
/ /
< ^
r"
z
ro
O
/
/
^ 7 ~ ^ •tL*—***
-
"•-•
1
0.5
1.0
1.5
2.0
2.5
CONTROL
BUFFER AREA LENGTH/WASTE AREA LENGTH RATIO
FIG. 3 Effectiveness of the grass buffer zone in removing
TKN from rainfall runoff.
amount of TKN that could be washed from the grass
after each waste application at about 100 kg/ha.
Mechanisms, such as waste drying to grass, grass uptake, ammonia volatilization, microbial assimilation,
and rainfall reduced nutrient levels between waste applications. The amounts that could be washed from the
grass immediately after the waste was applied, expressed
as percent of the amount applied, were 77 percent of the
TKN, 94 percent of the T-P, 96 percent of the COD, and
100 percent of the TOC and CI. The lower recovery of
TKN is likely due to ammonia volatilization since ammoniacal nitrogen was about 40 percent of TKN in the
applied waste.
When grass samples were washed 3 days after waste
application the amount of TKN, T-P, TOC and COD
washed from the grass was reduced compared to immediately after application, suggesting that time of application in relation to time of rain would be important in
controlling the runoff concentration. With additional
waste applications during a period without much rain,
the grass washing data showed a relative buildup on the
vegetation of T-P, TOC, and COD compared to TKN
and CI. Again, ammonia volatilization likely caused
most of the reduction in TKN recovery. Chloride was lost
from the grass only during rainfall; CI concentrations remained constant during dry periods and dropped to
background levels after even small rainfall events. Since
nitrate levels were never detected in the grass washings
during the experimental period, nitrification of organic
nitrogen on the grass did not occur, or nitrate utilization
was equal to nitrate production. Even though aerobic
conditions were probably prevalent for the waste on the
grass, the microbial populations may not have been
favorable for nitrate accumulation. Also, most of the
grass samples for washing were taken immediately after
waste application or after the grass had been exposed to
one or more rain events since application.
1980—TRANSACTIONS of the ASAE
0.5
1.0
1.5
2.0
2.5
CONTROL
BUFFER AREA LENGTH / WASTE AREA
LENGTH RATIO
FIG. 4 Effectiveness of the grass buffer zone in removing
NO3 from rainfall runoff.
Values for the surface soil TKN were variable even
though a large number of samples were taken and
averaged together. The general trend indicated that a
slight buildup of TKN occurred with time (Bingham,
1978).
Generally, runoff concentrations of all pollutants
measured were greater for small runoff events than for
large events. Reductions could not be shown with buffer
distance when small events were analyzed, because concentrations for small events usually varied widely depending on how clean the sampling systems were initially.
Therefore, only the large runoff events are presented.
The reduction of runoff concentrations in a vegetative
buffer area depends primarily upon infiltration or filtering of pollutants in the buffer area and dilution by rainfall in the buffer area. The amount of pollutant to be
removed or diluted in the buffer area depends on the
pollutant loading coming from the waste area, and the
amount of dilution rainfall required to reduce pollutant
concentration to a chosen level depends upon the volume
and pollutant concentration of the runoff from the waste
area. Amount of pollutant transport and volume of
runoff from the waste area normally increase with increasing size of waste area. Pollutant concentrations in
runoff from the waste area are likely to be variable and
can depend upon several factors such as waste type,
waste application rate, rainfall intensity, cropping factors, time since waste application, previous rainfall, etc.
In order to consider both size of waste area and size of
buffer area, the runoff concentration data was plotted
against the ratio of buffer area length to waste area
length. However, conclusions drawn from this data
should be applied with caution to sites with large waste
areas since the only waste area lengths used in this experiment were in the range of 8.7 m to 13 m.
Milligrams of pollutant per liter of runoff is plotted
333
Days after
waste applied
Rainfall
Number of
previous events
10-26-77
Rainfall
cm
5.46
11-06-77
437
5
1-08-78
2.56
4
1
1-14-78
4.32
9
2
Date
0.5
Days after
No. of previous
waste flooded
events
1
15
1
1-17-78
2.08
13
3
1- 19-78
442
15
4
1-25-78
2.78
2!
5
4-26-78
14.00
5
0
5-08-78
4.34
3
0
10
1.5
2.0
2.5
CONTROL
BUFFER AREA LENGTH/WASTE AREA LENGTH RATIO
0.5
1.0
1.5
2.0
2.5
CONTROL
BUFFER AREA L E N G T H / W A S T E AREA L E N G T H
RATIO
FIG. 5 Effectiveness of the grass buffer zone in removing
T-P from rainfall runoff.
against the ratio of buffer area length to waste area in
Fig. 3 through Fig. 9 for TKN, N0 3 -N, T-P, COD, TOC,
CI, and the volatile solids/total solids ratio. Generally,
the data show that concentration reductions still took
place at the 0.5 and 0.75 buffer area length/waste area
length ratio for the events measured. However, all
parameters usually approached the background area
runoff concentration at a buffer area length/waste area
length ratio of 1.0. The variation in concentrations from
FIG. 6 Effectiveness of the grass buffer zone in removing
COD from rainfall runoff.
one event to another was affected by the number of days
since the last waste application, previous rainfall, and,
probably, climatic and seasonal factors. The average
concentrations during the experiment at each buffer area
length/waste area length ratio are shown in Table 3.
A factor affecting the runoff concentration of TKN,
T-P, COD, and TOC was the number of days after waste
application. Generally, the longer periods between waste
application and rainfall resulted in lower runoff polluRAINFALL
DATE
0—0 10-26-77
• — • II - 06-77
-26-77
Date
Rainfall
cm
5.46
-06-77
-08-78
4.37
2.56
5
4
- 14-78
-17-78
4.32
9
13
-19-78
O
Day* After
No. of Previous
Wast* Applied
Events
1
15
2.08
4.42
1
1
O
1-08-78
5.46
4.37
2.56
4.32
2.08
4.42
2.78
14.00
2
3
4
15
-25-78
2.78
21
5
-26-78
14.00
5
0
-08-78
4.34
3
0
O
Z
3
UJ
a.
r,
0.5
1.0
1.5
2.0
2.5
CONTROL
BUFFER AREA LENGTH /WASTE AREA LENGTH RATIO
FIG. 7 Effectiveness of the grass buffer zone in removing
TOC from rainfall runoff.
334
4.0*
BUFFER AREA LENGTH / WASTE AREA
LENGTH RATIO
FIG. 8 Effectiveness of the grass buffer zone in removing
CI from rainfall runoff.
TRANSACTIONS of the ASAE—1980
RAINFALL
DATE
1-8-78
1-14-78
1-17-78
1-19-78
1-25-78
4-19-78
5-8-78
centrations at the end of the experiment compared to the
beginning. Probably the most evident trend is the effect
of previous rain on runoff concentrations. For example,
for each rainfall event from January 8 through 25, 1978,
the runoff concentration of TKN, N0 3 -N, T-P, TOC, Cl,
and the volatile solids/total solids generally decreased.
The average NH 4 -N/TKN and O-P/T-P ratios for all
the surface area length/waste area length ratios were
0.15 and 0.8 respectively. The NH4-N/TKN and O-P/TP ratios were measured for one and four rainfall runoff
events respectively. The NH 4 -N/TKN ratio ranged from
0.32 to 0.04, decreasing as the buffer area length/waste
area length ratio increased. The O-P/T-P ratio ranged
from 1.00 to 0.42 and also decreased as the buffer area
length/waste area length ratio increased. The average
NH4-N/TKN and O-P/T-P ratios for the control were
0.11 and 0.67 respectively.
Runoff volumes, rainfall volumes, and accumulative
infiltration/accumulative rainfall ratio (D) for large
runoff events on terraces 1, 4, and 7 are tabulated in
Table 4. The average runoff percentages for events on
October 26 and November 6, 1977, and on May 8, 1978,
for which volumes were measured for all the terraces,
were 8, 23, and 22 percent respectively. The variability in
runoff for different terraces was greater than expected.
This variability would affect total mass transport but did
not seem to have much effect on concentration.
RAINFALL
cm
2 56
4.32
208
442
2.78
2.80
434
o
h-
<
.5
1.0
1.5
2.0
2.5
CONTROL
BUFFER AREA LENGTH/WASTE AREA LENGTH RATIO
FIG. 9 Effectiveness of the grass buffer zone in reducing
the volatile solids/total solids ratio in rainfall runoff.
tant concentrations (Figs. 3, 5, 6, and 7). This
phenomenon was caused principally by the decreasing
availability of manure constituents with time. Apparently, the amount of these nutrients on the grass influences
runoff concentration of nutrients more than the amount
of nutrients on the soil surface, because the buildup of
nutrients on the soil surface did not increase runoff con-
CONCLUSIONS
Applying poultry waste to land application areas
resulted in an increase of the rainfall-runoff pollution
potential. TKN, T-P, COD, TOC, NO3-N, and Cl concentrations and the volatile solids/total solids ratio were
measured in the composite runoff sample at various buffer area length/waste area length ratios. Grass buffer
(Continued on page 342)
TABLE 3. AVERAGE CONCENTRATION OF RUNOFF POLLUTANTS AT EACH
BUFFER AREA LENGTH/WASTE AREA LENGTH RATIO
Pollutant Concentrations, mg/L
Buffer area length/waste area length ratio
Pollutant
COD
TKN
T-P
NO3-N
Cl
TOC
VS/TS
0
0.2
0.3
0.5*
96.93
6.88
5.06
9.46
4.03
87.83
5.88
4.66
9.12
4.73
28.11
0.33
74.8
5.60
2.39
7.9
96.15
4.89
2.12
0.20
4.27
26.5
0.40
32.5
0.29
29
0.35
5.0
0.75*
64.5
3.83
1.34
0.10
3.0
26.0
0.22
1.0
1.4
1.6
2.0
2.6
64.53
3.03
1.10
0.99
2.81
19.0
0.24
62.0
3.36
1.40
1.13
3.61
19.9
0.27
56.1
2.57
0.83
0.82
3.18
18.6
0.21
65.0
2.84
0.83
0.18
2.38
19.22
0.22
65.9
3.04
0.98
0.21
3.04
19.9
0.21
Contro
67.8
3.47
0.71
1.69
3.36
18.4
0.19
*For two events; other averages are for nine events.
TABLE 4. RUNOFF VOLUME, RAINFALL VOLUME, AND ACCUMULATIVE
INFILTRATION/ACCUMULATIVE RAINFALL RATIOS (D) FOR THE LARGE EVENTS
Terrace 1
RunDate
off
10-26-77
11-6-77
1-8-78
1-14-78
1-17-78
1-19-78
1-25-78
4-26-78
5-8-78
0.57
1.12
—
—
—
—
—
—
1.45
1980—TRANSACTIONS of the ASAE
Rainfall
5.46
4.37
2.56
4.32
2.08
4.42
2.78
14.00
4.34
Terrace 7
Terrace 4
RunD
off
0.90
0.74
0.14
1.48
0.70
2.27
0.75
2.20
—
—
—
—
—
—
0.67
—
—
1.24
Rainfall
5.46
4.37
2.56
4.32
2.09
4.42
2.78
14.00
4.34
RunD
off
0.97
0.66
0.73
0.47
0.64
0.50
0.61
0.46
—
—
0.71
—
0.93
0.24
1.26
0.32
—
0.17
Rainfall
5.46
4.37
2.56
4.32
2.08
4.42
2.78
14.00
4.34
D
0.89
0.91
—
0.78
0.88
0.72
0.88
—
0.96
335
Grass Buffer Zone Length
(Continued from page 335)
zones reduced the pollutant concentrations in the runoff
from land application areas to near that of surrounding
area runoff at a 1.0 buffer area length/waste area length
ratio on the clay loam soil studied. Less buffer area
would be needed if concentrations greater than
background conditions were acceptable. Waste area
lengths in the range of 8.7 m to 13 m were used in this
study and caution should be used when considering application of the results of this study to sites with longer
waste area lengths, or when the waste area and buffer
area are not similar to each other in vegetative cover, soil
surface condition, and hydrologic properties.
References
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Sheridan. 1977. Reduction of 2,4-D load in surface runoff down a
grassed waterway. Journal of Environmental Quality 6(2): 159-162.
2 Bingham, S. C. 1978. Effect of grass buffer zone length on
runoff of pollutants from land application areas. M.S. Thesis, North
Carolina State University, Raleigh.
3 Dickey, E. C , D. H. Vanderholm, J. A. Jackobs and S. L.
Spahr. 1977. Vegetative filter treatment of feedlot runoff. ASAE Paper
No. 77-4581. ASAE, St. Joseph, MI 49085.
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14 Swanson, N. P., C. L. Linderman and L. N. Mielke. 1975.
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ASAE, St. Joseph, MI 49085.
15 Thompson, Dale B. 1977. Nutrient movement during winter
runoff from manure treated plots. M.S. Thesis. Michigan State
University, East Lansing.
TRANSACTIONS of the ASAE—1980