vvEPA
                                United States
                                Environmental Protection
                                Agency
                                 Robert S. Kerr Environmental
                                 Research Laboratory
                                 Ada OK 74820
                                Research and Development
                                 EPA-600/S2-81-065 July 1981
Project  Summary
                                Cropping  Systems  for
                                Treatment  and  Utilization  of
                                Municipal  Wastewater and
                                Sludge
                                Boyd G. Ellis, A. E. Erickson, and Lowell E. Leach
                                  Land renovation of municipal waste-
                                waters is an attractive treatment
                                alternative to conventional sewage
                                treatment since the treatment achieved
                                is generally equal in quality to that of
                                conventional sewage treatment sys-
                                tems and is generally lower in cost. In
                                addition, many of the nutrients in the
                                wastewater applied to the land can be
                                removed through crop assimilation.
                                Additional treatment  occurs as the
                                wastewater percolates through the
                                soil profile toward the groundwater.
                                  The crops produced can be marketed
                                and their cash value applied toward
                                the capital cost, operation, and main-
                                tenance of the system. Corn is grown
                                as the major cash crop at the Muskegon
                                County Wastewater Treatment Facil-
                                ity in Michigan. Experience has shown
                                that corn is efficient in removing
                                nitrogen from applied wastewater
                                only during a few weeks during its
                                growing season. This lack of nitrogen
                                removal and elevated nitrogen levels
                                in the groundwater prompted this
                                study by Michigan State University to
                                develop more effective crop manage-
                                ment systems to remove nitrogen
                                from wastewater over a longer period
                                of time during the growing season. A
                                number of selective forages were
                                evaluated for their nitrogen removal
                                efficiency and effect on yield due to
                                competition with the corn. These
                                forages were sown in corn during
                                August, allowing them to become
                                established and provide winter cover
                                and also provide them an opportunity
                                for early emergence in the spring. The
                                corn was no-till planted in these forage
                                plots in the spring. During the planting
                                process, a strip of forage about 14
                                inches wide was killed with paraquat,
                                thus allowing the corn to begin grow-
                                ing without competition.
                                  Corn interplanted with one of the
                                forages was effective in removing
                                nitrogen from the wastewater but in
                                many cases, the corn yield was reduced
                                because of the competition of the
                                forage with corn for nitrogen. Corn in
                                rye  yielded about the same as corn
                                alone, but corn in  ryegrass yielded
                                considerably less than corn alone.
                                  Treatment  of applied wastewater
                                also occurs as the water percolates
                                through the soil profile. Intense moni-
                                toring of  the soil, soil water,  and
                                groundwater was conducted at multi-
                                ple  depths for a number of applied
                                nutrients and trace metals in all the
                                test plots throughout the study period.
                                  At the beginning of the second year,
                                the  project was expanded to include
                                an evaluation of wastewater spiked
                                with nitrogen to concentrations repre-
                                sentative of most wastewaters since
                                Muskegon wastewater is normally
                                low in nitrogen because it contains
                                industrial  wastewater. Nitrogen, in
                                the  form of liquid fertilizer, was in-
                                jected into the wastewater distribution
                                line  whenever half a revolution of the

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center pivot rig was completed. Thus,
half of Circle 26 received nitrogen-
spiked effluent and half received
wastewater of the concentration of
the normal treatment system.
  In addition to nitrogen stripping
studies, sludge compatibility and
metal contaminated sludge studies
were  conducted to determine the
feasibility of applying sludge to land
which is being used in a wastewater
treatment system. These sludge stud-
ies contained completely separate
objectives. One of the objectives was
to determine the loss of nitrogen by
leaching  from sludge applied to land
which is being irrigated with waste-
water. The other  objective was to
determine the compatibility of appli-
cation of metal contaminated sludge
to land being used for wastewater
treatment.  This sludge was generally
high in Copper (Cu), Iron (Fe), Nickel
(Ni), Chromium (Cr), and Zinc (Zn);
above average in Cadmium (Cd) and
Lead (Pb); and about average in Man-
ganese (Mg).
  Yield of corn was  increased  an
average of about 20 hectoliters per
hectare  (23 bushels/acre) for the
range of sludge loadings. It was deter-
mined that there was little advantage
in applying greater than 11 tons per
hectare (T/ha) of sludge as far as yield
was concerned.  Although  some yield
increase was obtained with addition of
22 T/ha, economically the returns
would favor the lower application
rates over larger acreage.
  The only heavy metal to be increased
significantly in the grain wasZn. Three
heavy metals, Zn,  Cu, and Ni were
shown to leach in the soil and to give
increased levels in the groundwater
under the highest  sludge application
rate. Low rates of  sludge application
(i.e. less than 54 T/ha) did not appear
to be a hazard to either the crop or to
groundwater contamination by leach-
ing through these sandy soils.
  The full  project  report (see next
paragraph), describes the experiments
and results in detail and recommends
management practices for nitrogen
control at the Muskegon Wastewater
Treatment Facility.
  This Project Summary was devel-
oped by EPA's Robert S. Kerr Environ-
mental Research Laboratory, Ada,
OK, to announce key findings of the
research project that is fully documen-
ted in a separate report of the same
title (see Project Report ordering
information at back).
Introduction
  Wastewater renovation by application
to land  has been practiced  in many
small  communities  throughout  the
United States at increasing numbers of
locations for the past fifty to sixty years.
Most of  the systems have either been
operated as high-rate infiltration sys-
tems for disposal, or as irrigation sys-
tems  in water-deficient regions for
increased crop yield through use of both
water and  nutrients. Little regard in
either operation was given to the actual
land treatment capability until recent
years. Investigation of systems in opera-
tion illustrated clearly that a high degree
of wastewater  treatment actually does
occur  as the water percolates through
soils combined  with various plants
utilizing  available nutrients. The applied
nutrients in the wastewater can be
utilized in the production of cash crops,
thereby providing a portion of the funds
for operation and maintenance of total
treatment systems.
  These facts prompted the construction
of the largest  municipal wastewater
land treatment system in the United
States. The system, located in Muske-
gon County, Michigan, collects munici-
pal sewage from the entire county,
aerates it, and places it in large storage
Fagoons  where  it is used to irrigate over
5,000 acres of corn  and a few  other
crops during the months of May through
October  each year.
  Corn,  however, the high  value cash
crop grown on the farm has been found
to actually be effective in removing
nitrogen from  the applied wastewater
only for a short  period of time during the
corn's growing season. Therefore, sig-
nificant amounts of nitrogen are leached
through  the soil profile as wastewater is
applied during the rest of the  irrigation
season. Lack  of adequate nitrogen
removal  prompted this study by Michigan
State University as detailed in the
following discussion.


Technical Approach
  Michigan State University's three-
year study of nitrogen management of
applied municipal wastewater through
special cropping practices was conduct-
ed at Circle 26 of the Muskegon Waste-
water Treatment Facility for the growing
seasons of 1976, 1977,  and  1978
(Figure 1). The prime objective of this
study was  to develop more  effective
crop management practices to remove
nitrogen from the municipal wastewater
used  to irrigate  crops for the total
irrigation season. The soils at this sit
are sandy and quickly react to loading <
wastewaters and sludge. During th
course of this study, evaluations wer
made of nitrogen  uptake and reduce
corn yield when forage crops such a
rye, ryegrass, and  oats were intercrop
ped with corn. These studies include
evaluation of the  soil  nitrogen statu
and nitrate movement to groundwatei
  A crop management system in whic
corn is no-till planted into fall establishe
oats, rye,  or ryegrass  cover crop wa
developed. This technique require
spraying a strip of forage about 1
inches wide with a herbicide (paraqua
to kill the strip of forage so the plante
corn could become established wit
little competition. The remaining forag
could then remove nitrogen until bot
the forage and corn competed for th
available nitrogen.
  Rye is a winter grain which is plante
in the late summer and is  used as
forage for livestockduring winter month;
It germinates and grows in the fall and i
dormant or slow growing in the winte
In the spring the rye grows rapidly an
matures in early summer. Its period (
maturing and reseeding is the  sam
period  in which corn is growing mo;
rapidly and adsorbing  nutrients at th
greatest rate. Since  the two crop
generally do  not accelerate in growth £
the same time, corn  and rye shoul
compliment each other almost perfect!'
  Other forage selectivity studies wer
also  performed to determine their pc
tential for nitrogen stripping whe
intercropped with  corn. These forage
included red clover, alfalfa, birdsfoc
trefoil, tall fescue, orchard grass, quact
grass, and reed canary grass. The fir;
three of those forages, when intercrop
ped with corn, resulted  in effectiv
nitrogen removal without appreciabl
reduction  in corn yield due to forag
competition.  However, yield of corn wa
drastically reduced when tall fescue c
orchard grass was the  forage of choic
because the herbicide used with the nc
till planter failed to give a satisfactor
stand. Quackgrass and reed canar
grasses were intermediate in their yiel
reducing efficiency.
  At the beginning of the  second yej
(1977), the  project was expanded  t
include an evaluation of wastewate
with a higher nitrogen content whic
would be representative of most waste
waters since Muskegon wastewater
lower than normal in nitrogen. Nitroge
was injected in the form of liquid fertil
zer, into the wastewater distributio

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 line whenever the center pivot irrigation
 rig completed a half revolution. Thus,
 half of Circle  26 received nitrogen
 spiked effluent, and half received normal
 wastewater. The nitrogen injection for
 the high-nitrogen studies boosted the
 average total nitrogen from 16 to about
 25 parts per million, which was less
 than anticipated. Apparently, a portion
 of the nitrogen in the spiked wastewater
 was lost by volatilization during spraying.
 Corn yield, nitrogen stripping with inter-
 cropped forages, and nitrogen leaching
 were compared for both levels of nitro-
 gen concentrations on separate halves
 of the study area. All the evaluations
 performed on the normal wastewater
 study plots were also performed on the
 nitrogen spiked half of the study area.
   In addition to the low and high nitrogen
 stripping studies utilizing forage crops
                         for wastewater treatment, two studies
                         were conducted to evaluate the applica-
                         tion of sewage sludge to agricultural
                         land. One of these studies was designed
                         to evaluate the compatibility of applying
                         sludge to  lands used for wastewater
                         treatment. The evaluation was conducted
                         on plots on which only corn was grown
                         during the  last two years of the study.
                         This sludge study was initiated in 1977
                         at the beginning of the nitrogen-spiked
                         wastewater studies previously described,
                         and continued through the 1978 grow-
                         ing season. The major goal of the study
                         was to determine the added  effect of
                         sludge application on corn yield, com-
                         pared to  the  selected corn and forage
                         nitrogen-stripping studies. This study
                         also includes a comparison of the fate of
                         nitrogen  added to the ecosystem by the
                         sludge and applied wastewater at two
in Tiie      $22 = 22T/HA Sludge
   ~~ — — —	 R = Replicate
          High Nitrogen
           Wastewater
                    Drain Tile
                                        'C-
                            Center^ Pivot
                                      Drain Tile
      Normal
     Wastewater
Drain Tile
RG
CR
Rz
CR
R^
RG
R2
C
CRG
CRG
R^
C
Sludge Rates
CR
RG
RA
/
CRG
R3
C
R3
RG
R3
CR
R3
C
RA
Forage Adaptation
CRG
RA

                                Drain Tile
figure 1.    Plot arrangement for low and high nitrogen N-stripping experiments.
different nitrogen concentrations. Prior
to crop planting each spring, a selected
number of high nitrogen tests plots
were loaded with sludge at two rates, 7
and  22 T/ha. The changes in the soil,
plant tissue, and groundwater were
monitored through time and compared
with data from plots where both low and
high nitrogen wastewater was applied.
  The objective of a second sludge
study, conducted  on separate  isolated
plots, was to evaluate the effect of
applying a heavy-metal contaminated
sludge to plots where corn is grown and
irrigated with municipal  wastewater.
This particular sludge was highly con-
taminated with metals from the Grand
Rapids,  Michigan industries and con-
tained   high   concentrations  copper
(Cu), nickel (Mi), cadmiun (Cd), zinc (Zn),
lead (Pb), and chromium  (Cr). Specific
plots were set aside and loaded with this
sludge at the rates of 11, 22, 54, and 99
tons per hectare during the first year.
The  plots were subdivided each suc-
ceeding year and retreated with sludge
each spring. Therefore, plots receiving
the highest metal additions exceeded
the suggested maximum by 2 - 3 times
for Cd, 13 - 14 times for Ni, 6 - 7 times
for Cu, and 12-13 times for Zn.
  A  number of  parameters were mea-
sured to determine the impact metal-
contaminated  sludge had on them.
These parameters were monitored for
the range of sludge loadings and include
grain yield, nitrogen uptake by the plant
tissue, and dry matter yields. Corn was
monitored for uptake of nitrogen (N),
phosphorus (P), potassium (K), calcium
(Ca), and magnesium  (Mg) both in the
plant and in the grain through its growth
cycle. Corn was also monitored for
heavy-metal uptake in both the plant
and  grain through its growth cycle.
These metals include Cu, Cd, Ni, Pb, Cr,
and Hg.
  Analyses of groundwater were not
part  of the original work plan of this
study; however, samples were collected
in the summer of 1978 under the highest
sludge application rate (99 + 81 +140
T/ha) and under the forage-corn treat-
ment of the nitrogen-stripping plots to
compare levels  of heavy metals in the
groundwater. This allowed comparison
of groundwater  collected beneath plots
where the maximum application of
metal-load in sludge was applied to that
of groundwater collected some  distance
from the area, thereby evaluating plots
with the highest potential for leaching.
The samples were split and half of each
sample was sent to the Robert S. Kerr

-------
 Environmental Research Laboratory in
 Ada, Oklahoma and the other retained
 at Michigan State University for analyses.

 Summary of Results
   Initially, the wastewater being ap-
 plied to the fields was sampled at the
 spray nozzles during the application of
 wastewater, and by collection vessels
 placed within the treatment areas.
 Although the  collection vessels  gave
 verification of uniform application rates,
 the samples tended to become contam-
 inated with dust and insects. Therefore,
 once comparisons indicated that the
 better samples were obtained from the
 spray nozzles, these data  were used.
 While there was considerable variation
 in the  individual  measurements,  a
 thorough  analysis  of the data did not
 show a consistent variation  along the
 length of the irrigation system. The
 amount of water applied for the whole
 1976 season was 12.4 mm (0.5 in) for
 each pass of the irrigation rig.
  The total wastewater applied during
 each season is tabulated in Table 1.
                   These values are much lower than the
                   1780 mm (70 in) per year for which the
                   system was designed. The poorly drained
                   soils,  with a less than adequate tile
                   drain system, resulted in application of
                   less than  the amounts designed for
                   Circle 26. There was no fall application
                   in 1976 because of the late planting and
                   slow drying of the corn and also the
                   early subfreezing temperatures which
                   occurred before late fall application
                   after harvest. The extremely wet condi-
                   tions  in the fall of 1978  prevented
                   irrigation on the high nitrogen side of
                   Circle 26.
                    The considerable day-to-day variation
                   in the composition of the wastewater is
                   caused by  the method of blending. The
                   most  notable variation is during the
                   period of the large nitrogen demand by
                   corn in late June, July, and early August,
                   when nitrogen is injected as part of the
                   crop  management by  the county. The
                   average nutrient contents, specific
                   conductivities,  and pH  values of the
                   wastewater are presented  in Table 2.
                   The Muskegon wastewater is low in
 Table 1.    Amount of Wastewater Applied Each Season

  Year                     Season
                                           Amount
  1976

  1977



  1978
Summer

Summer
Fall
Summer
Fall (Low N Only)
         mm

         835

         927
         1T4
Total    1041

         673
         343
                                                     Total Low N  1O16
phosphorus and nitrogen due to the
large proportion of industrial waters
collected by the system. The nitrogen
injection for the high-nitrogen studies
boosts the average total nitrogen from
16 ppm to 24.4 ppm, which is less than
was planned, but there appeared to be a
loss by volatilization in spray application.
  Evaluation of the effectiveness of the
various  intercropping experiments for
nitrogen extraction from the soil was
based on ammonia-nitrogen and nitrate-
nitrogen removal by the plants for the
entire growing seasons for the years of
1976, 1977, and  1978. As shown in
Table 3, during 1976 the various crops
were evaluated for the normal waste-
water (Low N) used for irrigation; then in
1977 and 1978 the experiment was
expanded to evaluate the effect of
nitrogen spiked effluent (High N).
  The ammonia-nitrogen (NhU-N) levels
were initially low in the soils and
remained low through the experiment
for  application of wastewaters for both
low and high nitrogen. In 1976, the
values were generally in the 1 to 2 ppm
range for the surface soil  and lower in
deeper horizons, indicating that the
ammonia (NH4) was rapidly being nitri-
fied to nitrate (NOs) in these well aerated
soils. Similar results were found in
1977, except that the last sample in the
fall  showed  an increase in NH4 in soil
layers to a depth of 30 cm, which was
attributed to the.effect of low tempera-
ture inhibiting the nitrifying organisms.
These higher values, which were still
present in the  spring of 1978, also
remained higher  during  the growing
seasons than the two previous years as
Table 2.    Summary of the Chemical Composition, Specific Conductivity and pH of the Applied Wastewater
Year and N/ level
1976 Low N
Std. Dev.
1977 Low N
Std. Dev.
1977 High N
Std. Dev.
1978 Low. N
Std. Dev.
1978 High N
Std. Dev.
Low N Avg.
High N Avg.
NO3

5.1
5.4
4.28
6.11
6.01
6.72
3.85
2.72
5.80
2.67
4.41
5.90
NH4

3.13
2.04
6.00
4.09
8.54
5.77
5.84
6.37
10.25
7.79
4.99
9.40
TKN

9.62
4.96
12.58
9.48
18.54
13.96
12.68
10.83
18.45
16.24
11.63
18.50
TN

14.48
6.05
16.86
15.20
24.55
20.05
16.53
12.54
24.25
17.24
15.96
24.40
Cl

" 	 -ppm
240
54
280
77
271
64
181
19
182
19
233.67
226.5
PO*

2.20
0.44
2.24
0.23
2.22
0.21
1.58
0.30
1.70
0.22
2.01
1.96
TP

2.30
0.54
2.31
0.41
2.46
0.75
1.68
0.53
1.92
0.36
2.10
2.19
K

10.9
1.6
10.9
2.1
10.7
1.1
15.0
5.0
16.6
4.5
12.27
13.65
Ca

65.6
10.4
70.2
8.9
69.1
9.2
86.5
20.0
86.8
23.4
74.07
77.95
Mg

14.4
1.9
19.5
7.9
20.2
8.8
14.7
1.3
14.4
1.5
16.2
17.3
Spec.
Cond.
- fi/mohs
1070
150
980
140
980
130
1080
130
1110
130
1043
1045
pH
8.11
0.26
7.73
0.26
7.76
0.27
7.75
0.29
7.79
0.19
7.86
7.78

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3 result of the failure of the drainage
iystem on this circle. Data show there
were no significant differences between
he NH4 distributions in the soil due to
 he cropping systems.  The well data
'eflect values less than 1 ppm nitrogen
is NH4 during the three-year study.
  The nitrate nitrogen (NO3-N) in the
soils was initially rather low in 1976,
/vhen wastewater irrigation  began  as
shown in Table 3. The N03-N levels
/vere even lower in the deeper soil
ayers. This is attributed to plant uptake
Df N03-N which caused the reduction of
M03-N with depth in the soil. The corn-
•yegrass treatment in 1976 was planted
is an oats-ryegrass mixture. The oats
quickly became established and reduced
he NO3 in the soil to the lowest concen-
ration of the three treatments. The soil
under the ryegrass treatment was inter-
mediate in NOa-N content because the
•yegrass developed more slowly. The
reatment of corn alone did not  reduce
soil N03-N until after July, when the
;orn had developed a full  canopy and
was in its stage of rapid  growth. There-
ore, corn alone was the poorest treat-
ment for removing N03-N from the soil
or the entire growing season, but was
somparable to  other treatments  from
 he 34th to the 39th week. Al I treatments
Decame less effective in reducing soil
M03-N after August.
  The low N plots of 1976 were con-
 inued into  1977 and  1978. During
 hese irrigation seasons, nitrogen-spiked
wastewater (high N) experiments also
were evaluated for the  three cropping
systems. By the spring of 1977, the rye-
jrass in the low N plots had become well
                             established and had the lowest N03-N
                             content in the surface soil. In May and
                             June,  the  corn-rye  grass and corn-rye
                             soils had less N03-N content in the soil
                             than the corn-alone plots as a result of
                             early nitrogen uptake of the grass in the
                             intercropping practices. However,  in
                             August and September, the  vigorously
                             growing corn  in the plots  with corn
                             alone had the same  or slightly lower soil
                             NO3-N content than the intercropped
                             plots.  The high nitrogen plots were
                             established in an oats cover crop as in
                             previous experiments to simulate over-
                             wintering rye.  All plots had an  initial
                             content of about 15 ppm nitrogen  as
                             NO3 in the surface soil. The ryegrass
                             grew quickly and reduced N03  in the
                             surface soil to about 5 ppm nitrogen in
                             about  four weeks, while the corn-oats
                             system was intermediate in reducing
                             the soil N03 content. At the 15-30 cm
                             depth, the intercropped corn reduced
                             the NOa content of soil beginning in
                             June each year to  below that of corn
                             alone. The soil-under-ryegrass plots
                             always had the lowest N03 content
                             during both years of the high nitrogen
                             experiments. The corn-oats system was
                             similar to corn alone in July but  in
                             August as the  oats matured, the corn
                             in  both treatments  did equally well in
                             reducing N03 in the profile.
                              The  most significant changes,  as far
                             as  the N stripping project is concerned,
                             are the changes in N03-N concentration
                             in the  leached water. In 1976, the corn-
                             rye treatment in which oats simulated
                             rye the first year, kept the N03-N in well
                             water  lowest early  in the season,  re-
                             flecting the uptake by the quick growing
Table3.
 Year
Nitrate Content of Soils-N-Stripping Experiment

                                   Treatment
                                 Corn
                                    Corn-Rye
                                   Ryegrass
    Sample
LowN  High N  Low N  High N  Low N High N
1976
1976
1976
1976
1977
1977
1977
1977
1978
1978
1978
1978
Week 20
Week 20
Average
A verage
Average
A verage
Week 47
Week 47
Average
Average
Week 48
Week 48
0-1 5cm
15 -30cm
0-1 5 cm
15-30cm
0-1 5cm
15-30cm
0-1 5cm
15 -30cm
0-1 5 cm
15 -30cm
0-1 5cm
15 -30cm
1.9
1.7
3.5
2.1
4.3
3.8
2.0
0.8
3.7
1.7
3.8
1.5


7.1
3.4
2.8
1.0
4.4
2.1
10.4
3.5
ppm N
2.5
1.8
2.2
1.6
4.7
1.4
2.1
1.1
4.0
1.6
3.7
1.0
as No3

7.0
3.1
4.1
1.8
4.0
1.9
11.4
4.4
2.2
1.6
3.1
1.8
2.9
0.9
0.9
0.3
2.7
1.2
3.5
1.4


5.6
2.4
2.5
1.0
3.1
1.4
7.2
2.1
oats. These low concentrations were
continued by the N03 stripping of the
ryegrass and corn. Initially, the ryegrass
plot lost NOa-N  by leaching, but as the
grass became established  it was very
efficient at removing N03-N.
  The corn-alone plots only stripped
NO3-N for a month which showed up in
the low N03-N well samples in August.
The average NOa-N concentration in the
well water for the first season was 3.7
ppm for the corn-ryegrass with oats, 6.2
ppm for the ryegrass alone and 8.0 ppm
for the corn alone.
  In 1977, the low N  experiments
showed the real benefits of the inter-
cropping systems at reducing N03-N in
the leached water after the initial
starting year since all the first-year
treatments were not complete. The
N03-N in the well water below the corn-
alone plots was rarely below 5 ppm, and
during periods when extra N was being
added to increase corn  production  on
the farm, the concentrations rose to
above 15 ppm indicating that corn alone
is a poor nitrogen stripper. The corn-rye
system, which was always better than
corn alone, had an average of about half
as much NOs in the well water; the corn-
rye  system never allowed a concentra-
tion over 10 ppm. The ryegrass had the
lowest NOa in well water, averaging 2.1
ppm and with only one  value above 5
ppm. The  corn-ryegrass  intercrop sys-
tem was  similar to ryegrass alone;
however, this was because the ryegrass
was  not sufficiently controlled to pro-
duce an acceptable corn crop. On the
high N  side of the experiment, the data
indicated the  intercropping plots were
not significantly different from corn
alone.
  In 1977 the N stripping sludge plots
were established using sludge additions
of 7 and 22 T/ha in the area irrigated
with high N wastewater. These plots
had only corn  as the crop and were thus
directly comparable to the corn-alone
stripping studies. The N03 content of
the surface layer of soil under the corn
alone plots was moderately high early in
the season. The 7 T/ha sludge applica-
tion increased the NOa content of the
surface  soil slightly; this increase per-
sisted for  at least three weeks before
being reduced to a value near the
control. The 22 T/ha sludge application
increased the soil NOa significantly.
  The increased levels of N03 in the sur-
face soil are reflected in the 15-30  cm
layers.  Both  sludge applications had
higher values of NOa in the subsoil  for

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several weeks. In fact, at the 15-30 cm
depth the soil NO3 on the 22 T/ha plots
was always higher, except during the
mid-July to mid-August period, when
the corn on these plots was growing
vigorously and reduced the N03 levels to
the level of the no-sludge corn plots. It
can be concluded that immediately after
the application of  sludge, well aerated
conditions prevailed, allowing the readily
available nitrogen  in the sludge to be
converted to NOs which is readily leached
unless  the  corn is in its rapid-growth,
maximum-demand stage, where it can
absorb the N03. Sludge, when applied at
22 T/ha, increased the concentration of
NOs-N  in the well samples, but the
application of 7 T/ha sludge did not
increase the nitrate content of well
samples. Thus, applications of low
amounts of sludge is an acceptable
practice.
  The yields of corn grain and silage
(Table 4) are similar to those obtained on
similar  soils on the Muskegon Waste-
water Treatment Facility farm operation.
Corn and corn-rye cropping systems
produced the same corn grain and
silage yield  except  on the high N plots in
1977 when oats were used to simulate
overwintering rye. This intercropped
forage was  too competitive for the corn.
The ryegrass intercrop significantly
reduced corn grain and silage yields
except  in 1978, when there was an
overkill of the ryegrass to the extent that
nitrogen stripping was impaired. The
addition of sludge beginning in 1977
corrected the infertility of this poor soil
and gave excellent yields but did add to
the NOa leaching. The yield of corn in
1978 was  suppressed compared to
1977 which may have been the result of
too much water on these soils which
have a poor underdrain system particu-
larly on the  north half of circle 26. Corn-
rye has proven to  be an acceptable N-
stripping winter crop without reduction
in yield; however,  corn-ryegrass would
need to be  better  controlled to reduce
the forage competition before it could be
advocated.
  The supplementary forage experi-
ments  demonstrated that all of the
forages, with the exception of crown
vetch, can  be grown at the Muskegon
Wastewater Facility. The crown vetch
had difficulty in germination and never
became a well-established stand. All
the others were no-till planted to corn in
1978 and their yields are presented in
the detailed manuscript. All the legumes,
rye,  ryegrass, and the natural quack-
grass crops were compatible as an
Table 4.    Yields of Corn and Silage on N-Stripping Experiment
                                   Corn Grain
                            Corn Silage
           Crop
1976    1977
1978
                       1976
1977
1978

Low N Corn
Low N Corn in Rye
Low N Corn in Ryegrass
High N Corn
High N Corn in Rye
7 T/ha Sludge on High N Corn
22 T/ha Sludge on High N Corn
LSD (.05)

40.6a*
42.6a
23.5b





hl/ha
68.9b
71.5b
36. 6c
72.56
42.6c
92.5a
89. lab
18.8

53.4a 26.0
54.1 a
49. Sab 6.4
35.4abc
21.7c
32.8bc
52.7 ab
18.5
T/ha
26. 3b
25. 7 b
13.7c
25. 3b
14.3c
35.7 a
34.7 a
8.2

29. 6 a
28. 5 a
25.4ab
23.4ab
14.5b
20.9 ab
20. 9 a
10.6
"Yields with the same letter are not different from others in the same column.
 intercrop. Reed canary grass, tall fescue
 and orchard grass would not be suitable
 in these soils because their dense root
 system would interfere with the no-till
 corn planter. If these forages were used
 they should be tested as to their N
 stripping abilities.
  An experiment was  established to
 study the influence  of metal loading
 rates from a metal-contaminated sludge
 upon crop yield and  the movement of
 heavy metals under irrigation. Applica-
 tion of sludge to a wastewater treatment
 system such as the one at Muskegon is
 considerably different from applying
 sludge to agricultural  lands in a conven-
 tional dry land or irrigated production
 system. First, the soils at Muskegon are
 very sandy which will provide maximum
 opportunity for sludge to be decomposed
 by  microorganisms  because of well
 aerated conditions in the soil. Secondly,
 the water  application rate is much
 higher than in conventional agricultural
 systems even where  irrigation is prac-
 ticed. Thus, the Muskegon Wastewater
 Treatment Site allows for  evaluation of
 metal contaminated sludge application
 to agricultural lands under conditions in
 which problems are most likely to occur
 due to leaching of nutrients and heavy
 metals into the groundwater.
  Sludge from the Grand Rapids, Michi-
 gan Municipal Wastewater Treatment
 Facility was transported to the test site
 where it was applied by spreading
 weighed quantities. A randomized block
 design with five  treatments (0, 11, 22,
 54, and 99 T/ha) and four replications
 were used. The experiment was modified
 by  splitting the  11,  22, and 99 T/ha
 treatments in  1977 and adding yearly
 sludge applications to one half of each
 plot.
  The  concentration  of all major plant
 nutrients (N, P, K, Ca, and Mg) in this
 sludge would be considered about
          average for sewage sludges. This sludge
          was high in Cu, Fe, Ni, Cr, and Zn, above
          average in Cd and Pb, and average in
          Mn. The quantity of metals added to the
          soil by the sludge applications were
          quite substantial, particularly  at the
          high rates. Maximum metal loadings to
          agricultural soils have been suggested
          by  a North Central Regional Research
          Committee. For soils like those  in this
          study, having a cation exchange capacity
          of less than 5 meg/1 OOg, the maximum
          lifetime metal loadings suggested in
          Kg/ha were: Cd - 5.6, Ni - 56, Cu -140,
          Zn - 280, and Pb - 560. The total quantity
          of metals  added to plots retreated with
          the highest sludge rate in 1977 and
          1978 was: Cd -12.6, Ni - 770, Cu - 930,
          Zn - 3,490, and Pb - 370 Kg/ha.  There-
          fore, plots receiving the highest metal
          additions (i.e. the "99 + 81+140" plots)
          exceeded the suggested maximum by 2-
          3 times for Cd, 13-14 times for Ni, 6-7
          times for  Cu, and  12-13 times for Zn.
          Only about 2/3 of the suggested maxi-
          mum Pb loadings was added. While the
          research committee's expected lifetime
          loadings for these five metals were con-
          sidered to be conservative, the impact of
          metal loadings at levels which are 6-19
          times these suggested maximums are
          largely unknown.

            The  effects of the above indicated
          metal  loadings on plant yield, plant
          composition, and  metal mobility and
          movement in the soils were thoroughly
          investigated. The effects of the range of
          metal contaminated sludge loading on
          corn grain yield are given in Table 5. The
          yield response to the sludge application
          in the initial year of study was dramatic.
          Eleven T/ha of sludge increased the
          yield from 64 to 102 hl/ha (73  to 117
          bu/acre).  Further yield increases from
          additional sludge loadings were small
          and statistically insignificant. Data in
          Table 5 indicate a gradual decline in

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Table 5.    Grain Yields from Metal Contaminated Sludge Study

                                           Grain Yield
 Treatment
1976
1977
1978
A verage

No Sludge
11
11*
22
22*
54
99
99*
LS.D.

64.4b
101.7a

107.7a

1 1 1 .9a
98.5a

18.9
- hl/l
77. 2c
81.1 be
96.8ab
93.3abc
99.9ab
92.0abc
93.2abc
100. 8 a
16.2
l,oif . 	
46.4c
59.4abc
70.6ab
52.0bc
73.2a
68.2ab
74.0a
67. Gab
17.6

62.7
80.7
83.7
84.3
86.6
90.7
88.6
84.2

 * Annual application (11 + 11 + 11,22 + 22 + 22, and 99+ 81 + 14017 ha, respectively).
 ^Numbers followed by the same letter within a column are not significantly different
  at the 5% level.
nutrient availability with  increased
sludge loading as the nutrients were
utilized by the crop, leached, or fixed by
the soil.
  The economic benefit of multiple
addition of sludge applications  in suc-
cessive years was evaluated based on
the value  of additional corn produced.
There appeared to  be an  economic
benefit from applying some sludge each
year.  Although the average yield for a
single application of 11 T/ha of sludge
was 18  hl/ha  (20.7  bu/acre), most of
the increase came in the first year.  The
yield increase from residual sludge was
3.9 and  12.0 hl/ha in 1977 and 1978,
respectively, compared  to  untreated
plots  but an annual  application of 11
T/ha  sludge gave 19.6 and 21.4 hl/ha
increase for the years of 1977 and 1978,
respectively. These facts illustrate  the
economic feasibility of annual  sludge
loadings. Since it is probable that sludge
would be in short supply, the question
was posed whether or not it would be
more economical to apply lowquantities
of sludge over a large acreage or apply
larger quantities  to smaller acreages.
Assuming there  is a uniform cost  per
ton of sludge applied, calculations of the
return were made for each case.  The
conclusions were that the  maximum
economic  benefit would  be gained by
applying a small quantity of sludge  to a
larger acreage.
  Heavy-metal uptake in the corn plants
and grain  was monitored for all three
years of the study. The Fe and  Mn
content of plant tissue showed appre-
ciable decrease  in uptake with years
over all treatments. The major decrease
in Fe content occurred between the first
and second sampling in 1976, while the
               Mn decrease was approximately linear
               each year. The authors speculate that
               this reduction pattern in uptake was
               probably due to an  increase in soil pH
               caused by the application of wastewater.
               There was still adequate Fe in the plant
               in  1978 for good growth but the Mn
               content became lower than desirable
               for optimum yield by 1978.
                The Cu and Zn uptake patterns in the
               plant tissue were similar. Data clearly
               indicate that Cu uptake was increased
               by  sludge application. However, the Cu
               content of plants grown on the control
               plots decreased from 1976 to 1978,
               probably due to the  increased pH of the
               soil. The same effect was observed but
               was more pronounced for Zn. In 1976,
               the application of sludge increased the
               Zn  content of plants from about 100
               ppm to over 300 ppm. By 1978, the Zn
               content of plants grown on the control
               were about 30 ppm and those from the
               highest sludge rate were down to about
               100 ppm. This decrease in uptake from
               1976 to 1978 could also be accounted
               for by changing corn hybrids during
               each year since hybrids are known to
               absorb varying quantities  of Zn when
               grown in the same environment.
                Zinc was the only heavy metal of
               those monitored whose content  was
               increased  in both the tissue and the
               grain by sludge application. A nearly
               linear increase in  Zn content of both
               tissue and grain occurred in 1978. The
               Zn  content of the  grain was nearly
               doubled by the highest sludge applica-
               tion (3,490 Kg Zn/ha). However, thisZn
               level in the grain would not be considered
               toxic to either animals or humans. The
               Zn  content of plant tissue from the
               sludge treated plots in the  initial year
were very high but not high enough to
be  toxic to  either plants or animals.
Although there was an increase in Zn
content in the corn grain, the increase
was relatively small compared to the
increase in  the plant tissue. The in-
corporation  of cadmium (Cd) into the
food chain through the use of sludge on
agricultural land is of major concern.
The sludge  used in this study had  a
moderate Cd concentration and  12.6
Kg/ha of Cd were applied to the high
sludge loaded plots over a  three year
period.  The Zn  application from this
sludge was more than 100 times the Cd
rate.  Nevertheless, some apparent in-
crease  in Cd occurred in the young
tissue in 1976 but was near the detec-
tion limit. No Cd was detected in plant
tissue in 1977 and 1978 and no Cd was
detected in the grain in any year.
  The data indicated that sludge appli-
cation did not significantly affect the Pb,
Ni,  Cr, or Hg content of the plant tissue
or grain, although an evaluation is
difficult since  metal  concentrations
were usually at or below detection
limits.
  Both DTPA extractable and total heavy
metals were followed in the soils
throughout the three years of  the ex-
periment. Soil analysis for the  surface
soil (0-15 cm) showed a linear increase
in DTPA extractable Zn with Zn applied
in the sludge in 1976. About one-sixth
of the Zn applied in the sludge was
extracted by the DTPA at the end of the
season. The next soil layer (15-30 cm)
showed an elevated Zn content at the
highest Zn  application rate  but no
increase at the lower loading rates. The
extractable Zn in the surface layer de-
creased considerably by the end of 1977
but did not change appreciably in 1978.
Analyses indicate that a portion of the
Zn migrated into the groundwater while
the major portion of that applied over
the three year study precipitated in the
soil  as  pH  increased  with  additional
sludge and wastewater.
  DTPA extractable  Cu and Ni both
increased linearly in the surface layer
with application rate similar to Zn. Even
though Cu was more variable than Zn
the  trends were similar. About 10 per-
cent of the added Cu was DTPA extract-
able. As with Zn, theCu level  inthesub-
soil was increased by the highest appli-
cation of sludge during the first year.
However, Cu did not become less soluble
with time as did Zn. This is understand-
able since it is known that Cu  will
remain available for many years in soils

-------
once it has been applied and is not so
dependent on soil pH as are other heavy
metals. The Ni level in the soil decreased
with time particularly at high levels of
applied Ni.  Data indicated that Ni was
leached into the soil profile in a manner
similar to Zn. The DTPA extractable
levels of  other heavy metals were not
increased by the addition  of sludge
which would  suggest that they should
not be susceptible to leaching or in-
creased plant uptake.
  Groundwater samples were collected
in the summer of 1978 under the highest
sludge application plots (99 + 81 +140
T/ha) and under the forage-corn treat-
ment of the N stripping plots where no
sludge had been applied. Sampling from
these separate'areas provided a com-
parison of the levels of heavy metals in
the groundwater under the  maximum
application of sludge to a treatment that
was removed from the area assuring
that no contamination existed.
  Data clearly indicated that Zn, Cu, and
Ni all had leached into the groundwater
under the highest sludge loaded plots.
Zinc values were approaching one ppm
and exceeded this value for one month
at the end of  summer. The level of Zn
applied to the  plots where groundwater
samples  were collected was 3,490
Kg/ha, which is clearly an  exorbitant
quantity of Zn to apply under any  cir-
cumstance. The results would indicate
that an undesirable  quantity of Zn
reaches the groundwater under such
high loading rates.
  The Cu increase in the groundwater
beneath the high  sludge  loaded plots
was about double that of the control
area. Thus, movement was confirmed
which agrees with the DTPA extractable
soilCu and Zn values but the quantity of
Cu is not excessive even under the high
quantity of Cu addition (930 Kg/ha).
  Like Cu and Zn, Ni content of  the
groundwater also increased under
sludge application. The quantity of
increase appeared to be intermediate
between Cu and Zn and again indicated
that movement was occurring. No  de-
tectable Hg was found in the ground-
water at any time. Increases of Cr,  Cd,
and Pb may have occurred but the great
variation between replicate samples
made this  uncertain since surface
contamination is possible.


Conclusions
  As a result  of this research effort, a
number of conclusions can  be drawn
concerning the fate of nutrients and

                                 8
heavy metals applied to sandy soils at
municipal wastewater land treatment
sites which are used to grow corn as a
major cash crop.
  In the nitrogen stripping studies, the
nitrogen added in the wastewater was
rapidly converted to nitrate nitrogen
(N03) leaving very low levels of ammonia
nitrogen (NH«) in the soil during two of
the three years of  study.  Even during
periods  when rainfall combined  with
wastewater resulted in poor soil aeration,
levels of NH4 rarely exceed 4 ppm in the
soil profile.
  Corn grown alone was only effective
in removing  nitrogen during a four-
week period  during  its rapid growth
near maturity beginning in late July. At
other times  the N03 levels  moving
through the soil were near those of the
applied water.
  Ryegrass forage was the best treat-
ment for removing nitrogen from the
wastewater for the entire season. How-
ever, during the four week period dis-
cussed above there was little difference
in cropping systems with respect to the
quantity of  nitrogen removed.
  Intercropping forage with corn reduced
the total nitrogen leached considerably
when compared to corn alone. The
Muskegon system was generally nitro-
gen deficient leaving a delicate balance
where the corn yields were reduced by
as much as 50 percent if the forage was
too vigorous. When forage was con-
trolled with paraquat the intercropped
corn yielded  about the same as corn
alone.
  A management system where rye is
strip killed with paraquat and then no-
till corn planted  will produce a satis-
factory management system to effec-
tively strip nitrogen from the water and
produce a satisfactory corn yield. The
varieties of rye used in this study did not
shatter in the field to reseed themselves
in late summer. A search for varieties of
rye which would shatter when matured
could preclude seeding the rye each
year.
  A study to compare different forages
showed that corn intercropped with red
clover, alfalfa, birdsfoot trefoil, and
ryegrass gave satisfactory yields. Yields
were drastically reduced when  tall
fescue or orchard grass was the forage.
Rye, quackgrass, and reed canary grass
were intermediate in affecting yield.
  When sludge was applied to an area
receiving about 24 ppm  nitrogen in the
sprayed wastewater,  a sludge loading
rate of 7 metric tons per hectare (T/ha)
gave little increase in NOs in  the soil.
However,  when sludge was applied at
22 T/ha under the same conditions,
N03 increased in both the surface and
the 15-30 cm layer of soil.
  The application of sludge at about 11
T/ha increased the corn yield from 64 to
102  hectoliters per hectare (73 to 117
bu/acre).  Rates of sudge application
above 11 T/ha did not show an appre-
ciable increase in yield over the 11 T/ha
rate. Economically, the returns would
favor application of a 11 T/ha rate over a
large acreage rather than heavy appli-
cations of  sludge to small acreages.
  Zinc (Zn) was the  only metal to be
significantly increased in the corn grain
by the additions of sludge. Although the
level was increased from about 30 to 50
ppm Zn in the grain,  this level is quite
safe in a food grain. Zinc, Copper (Cu),
and  Nickel (Ni) were found to move in
the soil and to give increased levels in
the groundwater under the highest
sludge application rate (3,490, 930, and
770  Kg/ha) of Zn, Cu, and Ni, respec-
tively. Zinc content of the groundwater
was  increased from about 0.1 ppm to
about 0.8  ppm, Cu from 0.04 to 0.13
ppm and Ni from 0.03 to0.07 ppm under
the heaviest sludge application as com-
pared to no sludge. Low rates of sludge
(less than 54 T/ha) did not appear to be
a hazard to either crop or leaching on
these sandy soils.

Recommendations
  Effective treatment  of wastewater by
land application  must include careful
management of the land and crop
resources  to obtain maximum nutrient
removal through high production  and
simultaneously produce  desireable
groundwater. Because of the inability of
corn to reduce NO3 in the soil solution
during  much of the growing season it
cannot be recommended as the crop
except for a system with very  low
incoming N levels (i.e. less than 10 ppm
N m the water being applied to the land).
  Land treatment systems receiving
wastewater containing high quantities
of N should consider forages or forages
intercropped with corn to renovate the
wastewater. A management system is
suggested where rye is intercropped
with corn by killing a strip of the rye with
a su itable herbicide at the ti me that corn
is no-till  planted. This reduces the
competition for nutrients  in the corn
until it reaches a height sufficient that it
will shade the rye and thus reduce the
competition. A rye that  shatters  easily
could eliminate the need to reseed the
rye each summer; however, the varieties

-------
that were used in this study resisted
shattering.
  Application of sludge is compatible
with wastewater treatment systems but
the application rate should be kept low.
At application rates less than 54 T/ha,
movement of heavy metals in the soil
profile did not appear to be a problem.
Uptake and translocation of heavy
metals into the grain were only noted in
the case of Zn. The recommendation for
a low application of sludge will give the
greatest economic returns per ton of
available sludge and at the same time
lessen the chance of leaching of metals
from the sludge.
BoydG. Ellis and A. E. Erickson are with the Department of Crop and Soil Science,
  Michigan State University. East Lansing, Ml 48824.
Lowell E. Leach is the EPA Project Officer (see below).
The complete report,  entitled "Cropping Systems for Treatment and Utilization
  of Municipal Wastewater Sludge," (Order No.  PB 81-187 254; Cost: $ 17.00.
  subject to change)  will be available only from:
        National Technical Information Service
        5285 Port Royal Road
        Springfield, VA 22161
        Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
        Robert S. Kerr Environmental Research Laboratory
        U.S. Environmental Protection Agency
        P.O. Box 1198
        Ada,  OK 74820
    , US GOVERNMENT PRINTING OFFICE 1981-757-012/7200

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