United States
                    Environmental Protection
                    Agency
Municipal Environmental Research
Laboratory
Cincinnati OH 45268
                    Research and Development
EPA-600/S2-84-128 S ept. 1984
6ER&         Project  Summary

                    Long-Term  Use  of Sewage
                    Sludge  on  Agricultural  and
                    Disturbed  Lands
                    T. D. Hinesly, L G. Hansen, D. J. Bray, and K. E. Redborg
                                                                                          'it1
                      Results are presented from two re-
                    ports on field studies done during a 15-
                    year investigation of the long-term use
                    of sewage sludge on  agricultural and
                    disturbed lands. These projects are
                    intended  to answer concerns about
                    how sludge applications to soils relate
                    to phvtotoxic accumulations of trace
                    metals and hazardous metal levels in
                    crops. Studies were conducted on plots
                    at the Northeast Agronomy Research
                    Center near Elwood, Illinois  at the
                    University of Illinois,  Urbana, and on
                    strip-mined land near Canton,  Illinois
                    owned by the Metropolitan Sanitary
                    District of Chicago.
                      The first study, entitled "Use of Sew-
                    age Sludge on  Agricultural and Dis-
                    turbed Lands," reports the results of the
                    following field studies: (1) response of
                    corn on three soil types previously
                    amended with annual sludge applica-
                    tions, (2) response of continuously
                    planted corn on Blount silt loam to
                    repeated annual applications of sewage
                    sludge, (3) response of winter wheat
                    and soybeans on Blount previously
                    amended with annual applications of
                    sludge, (4) sludge-amended strip-mine
                    spoils continuously planted with corn,
                    (5) differences in Cd and Zn uptake by
                    various corn hybrids, (6) effects of
                    cation exchange capacity on Cd uptake,
                    (7) uptake of metals by spinach from
                    Cd-spiked sludge, (8) response of chick-
                    ens to Cd in feed, and Cd-induced
                    growth depression and Cd accumula-
                    tion in chicks as influenced by dietary
                    modifications. The second study enti-
                    tled "Long-Term Use of Sewage Sludge
                    on Agricultural and Disturbed Lands."
reports on the following field studies:
(1) the response of corn to repeated
annual applications of sewage sludge,
(2) the differential uptake of selected
corn hybrids grown on sludge-amended
soils, and (3) the effects of high sludge
application rates on strip-mine spoil
characteristics and the  response of
plants.
  This Project Summary was developed
by EPA's Municipal Environmental Re-
search Laboratory,  Cincinnati, OH, to
announce key findings of the research
projects that are fully  documented in
two separate reports (see Project Report
ordering information at back).

Introduction
  Digested sewage sludge is an effective
source of N and P for the fertilization of
field crops. When applied at rates suffi-
cient to provide recommended rates of
supplementary nitrogen for nonlegumi-
nous crop plants, sewage sludge also
supplies  relatively large amounts of or-
ganic  matter. Thus  long-term use of
sludge changes the physical properties of
some soil types to such an extent that
crop yields frequently exceed those ob-
tainable with commercial fertilizers. Agri-
cultural use of sewage sludges eliminates
the high energy costs, potential air pollu-
tion, and ash disposal problems encount-
ered by sludge incineration. But sewage
sludges contain  trace elements in con-
centrations that often  greatly exceed
normal concentrations in productive soils.
Many environmentalists are therefore
concerned that heavy metals and metal-
loids  may accumulate and eventually
reach phytotoxic levels.  Some are con-

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earned that concentrations  of certain
trace elements may be enhanced in food
and feed  stuffs enough to  present a
health hazard to man and animals.
  The two reports summarized here
contain the results from segments of a
15-year investigation  of the long-term
use of sewage sludge  on agricultural or
disturbed lands. Studies were conducted
at the  Northeast Agronomy Research
Center near Elwood, through the Univer-
sity of Illinois at Urbana, and on Chicago
MSD strip-mined land near Canton, Illi-
nois. The purpose of the work reported
here was to determine  how sludge appli-
cations to soils relate to  phytotoxic accum-
ulations of trace metals and hazardous
metal levels  in crops. The first study,
entitled "Use of Sewage Sludge  on
Agricultural and Disturbed Lands," pre-
sents the results from eight field studies.
These  include investigations  of corn
responses to various soils previously or
currently amended with annual sludge
applications, corn responses to sludge-
amended strip-mine spoils, differences in
Cd and Zn uptake by various corn hybrids,
effects of cation exchange capacity (CEC)
on Cd uptake, metal uptake by spinach
from soil amended with sludge with and
without additions of CdCI2 and response
of chickens to biologically incorporated
Cd  in feed. The second study, entitled
"Long-Term Use of Sewage Sludge  on
Agricultural and Disturbed Lands," dis-
cusses the result of field studies on the
response  of  corn to  repeated annual
applications of sewage sludge, the  dif-
ferential uptake of Zn in two selected corn
hybrids grown on sludge-amended soils,
and the effects of high  rates of* sludge
applications on strip-mine spoil character-
istics and  the response  of plants. Each
report is summarized briefly here.

Use of Sewage Sludge on
Agricultural and Disturbed
Lands
  This report presents the results of 8
field studies,  which  are described  as
follows:
  Response of Corn on Three Soil Types
Previously Amended with Annual Appli-
cations—This field study was conducted
to determine the changes in metal uptake
by  corn after annual applications of
sewage sludge had ceased. The study
was conducted on lysimeter plots contain-
ing 3 contrasting soil types on which
sludge had been applied annually for 5
years (1969-73) at 3 different  rates-
maximum, half the maximum, and one-
fourth the maximum. Control plots were
fertilized and irrigated. After 1973, sludge
applications were discontinued on all
Blount silt loam plots and on all Elliott silt
loam  and Plainfield sand plots except
those that had received maximum sludge
applications. On maximum-sludge-treat-
ed Blount plots, the sludge applied per
hectare  was equal to 232.5 mt solids,
8,044 kg P, 58.3 kg Cd, and 1,290 kg zn.
After  sludge applications were  discon-
tinued in 1976 on maximum-sludge-treat-
ed plots of Elliott silt loam and Plainfield
sand, the sludge added per hectare was
equal to 423 mt solids, 14,785 kg P, 112.7
kg Cd, and 2,167kg Zn.
  Yields of corn  grain on Blount  plots
varied directly with the  annual rate of
sludge  application. After applications
ceased,  residual  sludge N in soil  was
adequate to maintain  corn yields  for 3
years without  decline. When  nitrogen
fertilizer was  applied in 1979, yields
returned to the average levels for the 10-
year period.
  After  sludge applications were termi-
nated, Cd and Zn levels in  corn  plant
tissues  decreased with time. Relatively
speaking, Cd  in  corn grain  decreased
more  rapidly than Zn. The greater the
level of Cd accumulated in soils through
additional incremental  annual sludge
applications, the more time was required
for Cd to decrease to background levels.
The availability of Cd and Zn for uptake by
corn  decreased  by about 50 percent
during the first year after sludge applica-
tions were suspended; thereafter,  it de-
clined more slowly.
  Response of Continuously Planted Corn
on Blount Silt Loam to Repeated Annual
Applications of Sewage Sludge—The
purpose of this study was to determine
the long-term benefits and adverse envi-
ronmental effects  of sludge use on land.
Before  this 3-year study, sludge had
already  been applied to field plots for 10
years at  3 rates (maximum,  half the
maximum, and one-fourth the maximum).
Data  in Table  1  show the amounts of
sludge applied  annually during the  study
(1978-80) and the accumulated total of
sludge applied  over 13 years.
  N and P applied to plots averaged about
10, 5, and 2.5  times the amount needed
for an optimum corn crop on maximum,
half maximum, and one-fourth maximum-
sludge-application plots, respectively. Af-
ter 1980, the following additions of
metals to soil had been applied (kg/ha):

    Cd  	  185  Ni .... 264
    Cu	1018  Pb.... 768
    Cr	2186  Zn....3652
Table  1.    Sludge Applied Annually and
          Accumulated Over the 13-Year
          Period on Maximum-Sludge-
          Treated Blount Silt Loam Com
          Plots

           Dry Solids Applied (mt/ha)
  Year  Annual
Accumulated
 Since 1968
  1978    68.4
  1979    62.5
  1980    45.8
   625.0
   687.5
   733.3
  Chemical composition of the  surface
soil was changed by the 13 years of
annual sludge application. The first 0- to
30-cm were enriched by organic C and
total N, though the soil level appeared to
have  reached equilibrium. Concentra-
tions of P and heavy metals were greater
than in control plots to a  depth of 30 cm;
but K, Na, Ca, Mg, and Mn concentrations
were  essentially  unaffected by sludge
addition. Levels of Cd, Cu, Cr, Ni, Pb, and
Zn were significantly increased to a depth
of 30 cm.
  Only concentrations of Cd, Cu, Ni, and
Zn were consistently increased in leaves,
grain, and stover of corn. Plots were split
in 1980, half of each plot was  planted
with a hybrid variety that  had been grown
in each of the  13 study years but that
would be unavailable in  the future. The
other half of each plot was planted with a
new variety that accumulated only about
half as much Cd (Table 2).  No phytotoxicity
was apparent in the 3-year period.
  Response of  Winter Wheat and Soy-
beans to Residual Sludge in Blount After
A nnual Sludge Applications Cease—Stud-
ies were conducted to determine whether
metal  uptake  by  soybeans and wheat
would decrease as the metal in the soil
reverted to a  less  available form or
whether the  uptake  would increase as
organic matter decomposed.
  Soybeans were  grown from 1969 to
1976 on plots that had  received sludge
applications at 3 rates since 1969. Control
plots  were fertilized  and irrigated with
water. Plots were split so that half of each
received extra  P (118  kg/ha). Sludge
applications were continued on the P-
treated halves when  P  toxicity  became
evident in 1972, but they were discon-
tinued on the untreated halves. The total
of sludge solids that had accumulated on
the maximum sludge plots was then 242
mt/ha. The P-treated halves continued to
receive sludge and grow soybeans until
1976, when  toxicity again affected  the
crop.  The total sludge  that  had been

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Table 2.    A verage Concentration of Cd in Corn Grain and Stover from Two Hybrids Planted on
           Plots of Blount Silt Loam

                                           (mg/kg dry weight)
       Item and Year
                  Sludge Treatment
No Sludge  One-fourth    Half
 (Control)   Maximum   Maximum  Maximum     LSD
Cd in Corn Stover
Pioneer 35 17
1978
1979
1980
Pioneer 3541
1980
Cd in Corn Grain
Pioneer 35 17
1978
1979
1980
Pioneer 354 1
1980

1.1
0.9
0.7
0.484

0.09

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from CdClz than CEC due to inorganic soil
components. Sludge properties appeared
to be an important factor in the control of
Cd uptake when Cd-bearing sludge was
applied to the soil.
  Uptake of Metals by Spinach from Cd-
Spiked Sludge—A greenhouse study was
designed  to determine whether  plant
uptake of Cd from sludges differed when
the latter were  spiked with Cd  salts
instead of containing the equivalent
amount of indigenous Cd. Ten different
sludges were used, with pairs containing
Cd levels of 40,140, 400, 600, and 1000
mg Cd/kg sludge solids. For the first four
Cd levels, all of the Cd was indigenous to
the sludge in one of each pair. But at the
highest  level, indigenous Cd had to be
supplemented with CdCI2 to achieve the
desired concentration.
  The study indicated that  spinach (an
accumulator of Cd) had higher concentra-
tions of Cd when  grown with the Cd-
spiked sludge than when grown with the
sludge containing indigenous Cd in the
same concentrations.
  Response of Chickens to Cd in Feed—
Because egg-laying hens consume larger
amounts of feed per unit of body weight
than other domestic  animals, chickens
were fed  high-, medium-,  and  low-Cd
diets to  determine possible  adverse ef-
fects of Cd-enriched feed  grown  on
sludge-amended strip-mine spoils. High-
and intermediate-Cd-accumulating corn
hybrids  were grown on spoils amended
with Chicago sludge. Concentrations for
the high-, medium-,  and low-Cd  diets
were 0.71,0.35, and 0.06 mg Cd/kg corn,
respectively. Soybean cultivars that took
up different amounts of  Cd were also
grown on sludge-amended spoil and their
meal was mixed with the high-Cd corn
meal to  produce feeds containing  2.38,
1.22, and <0.06 mg Cd/kg.
  Three hundred pullet chicks were sepa-
rated into lots of 25 each and fed a starter
diet. At 8 weeks, the diet was changed to
a developer diet, and  at 20 weeks to an
egg-laying diet. The birds were housed in
laying cages, with 2 birds in each cage.
High-, medium-, and  low-Cd diets were
each fed to four lots of birds (i.e., there
were 4 replications of birds on each diet).
When birds were sacrificed, Cd was
found in the crop, proventriculus, muscu-
lar  gizzard,  gizzard lining,  duodenum,
liver, kidney, pancreas, and spleen tissues
in proportion to Cd in the diets. Concentra-
tions of  Cd in leg muscle,  breast  muscle,
and  femur bone did  not  vary with diet
levels. When dietary Cd was decreased,
Cd decreased in all accumulatory tissues
except the kidneys. Eggs did  not accumu-
late Cd in proportion to the dietary level of
the metal. Nothing indicated that the
health, body weight gain, or egg produc-
tion of the chickens fed the high-Cd corn
and soybeans were affected.
  Cd-Induced Growth Depression and Cd
Accumulation in Chicks as Influenced by
Dietary Modifications—Nine experiments
were conducted with 1 -week-old, cross-
bred,  meat-type chicks to explore the
effects of dietary nutrient balance on the
response of chicks to Cd.  The element
was added to their corn-soya feed as
CdClj in incremental doses over a period
of 2 weeks. At 10 ppm, growth depression
occurred, and Cd content of kidneys and
livers increased as a result of the added
Cd. As the Cd intake was increased, the
percent of ingested Cd retained  in the
liver and kidneys also increased.
  Simultaneous decreases  in dietary Cd,
Zn, P, and  Mn  increased the growth
sensitivity of chicks to added Cd and
increased Cd retention without affecting
growth when no Cd was fed. When the
diet was adjusted to be  marginal in
methionine and Mn, supplementing the
diet with either of these nutrients did not
influence growth or Cd retention when
Cd was added to the diet. Added Cu did
not alleviate Cd-induced growth depres-
sion, but it  did increase  Cd  retention.
Supplemental  Zn  and Ca  levels  above
accepted requirements ameliorated Cd-
induced growth depression and reduced
the amount of Cd retained in livers and
kidneys.
  Chicks depleted of vitamin 0 during the
first week of life were found to be more
growth-sensitive to 10 ppm Cd in subse-
quent  2-week assays. High  levels of
vitamin D reduced the growth depression
and increased liver and kidney accumula-
tion of Cd in both vitamin-D-depleted and
undepleted chicks. When levels of Ca and
vitamin D that were marginal  for main-
taining normal bone ash were fed,  10
ppm of added Cd reduced tibia  bone ash.

  Conclusions—The conclusions from
the eight field studies are:

  1.   A phytotoxic condition is not likely
      to develop as a result of .the repeated
      use of the  Chicago sludge as  a
      fertilizer.
  2.   The high pH of  calcareous spoil
      failed  to control the uptake of Cd
      and Zn by corn to levels lower than
      those  observed on acid  Blount silt
      loam.
  3.  A one-time sludge application of
      about 200 mt/ha  may produce
      better quality grain and forage than
     could be obtained with an equiva-
     lent amount of sludge applied over
     several years at rates to supply
     recommended amounts of N. But
     special precautions will be required
     to  protect  ground water  against
     contamination with NOs-N where
     one-time, high-rate sludge applica-
     tions are made.
  4.  Data  from this  study  show that
     regardless of the nature of the
     mechanism, the losses of sludge-
     borne heavy metals from soils occur
     rather rapidly,  and  the amounts
     remaining for uptake by plants de-
     creases  with time  and  are not
     affected by applications of inorganic
     sources of N.
  5.  The decrease in  uptake of residual
     metal  concentrations in soil from
     previous sludge applications varies
     with differences in crop species and
     probably with varieties within a
     particular species.
  6.  Enhancement of heavy metal con-
     centrations in food and feed  stuffs
     can be controlled by plant breeding.
  7.  Data from studies involving the use
     of soluble Cd salts are of little value
     in predicting Cd uptake by plants
     grown on sludge-amended soils.
  8.  At the highest level of Cd that could
     be biologically incorporated in corn
     grain  and soybeans produced on
     sludge-amended fields,   nothing
     (body weight changes, egg produc-
     tion, or various clinical parameters)
     indicated that the enhanced  levels
     of dietary Cd affected the  health of
     the chickens.
  9.  Since  the highest possible level of
     biologically incorporated Cd in feed
     did not increase  levels of the metal
     in egg shells, whites, yolks, muscle
     tissues, or bones, the probability of
     increasing Cd in human foods to
     harmful  levels is very low.

Long-Term Use of Sewage
Sludge on Agricultural and
Disturbed Lands
  This  report describes the results of 3
field studies conducted during the  last 2
years of the full 15-year  investigation.
Each field study is described here briefly
along with conclusions and recommenda-
tions.
  Corn Response to Continuous Annual
Sludge Applications—The purpose of this
study was to investigate the cumulative
effects of the 14 consecutive  years  of
applying digested liquid  sludge  from
Chicago to 4 plots, each 6.1 by 12.2m (20

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by 40 ft). The plots were treated with
liquid sludge in furrows at 3 rates—31.8
(Table 3), 15.9, and 7.95 Mt solids/ha
(maximum, half the maximum, and one-
fourth the maximum rate). The  sludge-
treated plots  received 134 kg/ha  of
supplemental  K as  KCIg. Control plots
were fertilized with commercial fertilizer.
Corn was planted to produce  60,000
plants/ha.
  The amounts of various sludge constit-
uents applied in 1981 and over a  14-year
period on maximum-sludge-treated plots
are listed in Table 4.
  Metal concentrations in  soil  deeper
than 30 cm (12 in.) had been slight  or
undetectable, so only samples from 0- to
15-cm  and 15- to 30-cm depths were
analyzed  in 1981. Organic C and  N
increased to a depth of  only 15 cm. As
application rates increased, P, Zn, Cd, Cu,
Ni, Cr, and Pb increased significantly to a
depth of 15 cm; but concentrations of K,
Na, Ca, Mg,,Fe, and Mn did  not signifi-
cantly increase.
  Plant populations and corn yields were
not signficantly different for various
application rates or for fertilized control
plots, though  1981  yields were higher
than the average for the 14 years. Thus
14  years of high-rate applications  of
Chicago sludgedid not impair corn growth
or yield even on an acid soil.
  Sludge application increased the con-
centrations of only Cd  and Zn in  all corn
tissues. But Cd concentration increased
significantly more in the grain of the old
hybrid (Pioneer 3517) than that of the
                new hybrid (Pioneer 3541) (1.06  com-
                pared with 0.18). The new hybrid growing
                on  plots that  had  received  optimum
                sludge applications to supply N annually
                for  14 years did  not  exceed the  Cd
                concentrations expected  for conven-
                tionally.fertilized fields  (0.06 mg Cd/kg
                corn grain). Neither Cr nor Pb  were
                significantly increased  in  corn tissues
                after 14 years of sludge  application. Low
                but  statistically  significant  increases in
                Cu  and Ni were found in  corn tissues
                produced on plots treated with the two
                higher sludge loading rates.
                  Accumulations of Zinc by Corn Hybrids
                Grown on Blount Silt  Loam Amended
                with Sewage Sludge—The purpose of
                this study was to determine the constancy
                of differential uptake of  Zn  between two
                selected corn hybrids grown under field
                conditions on sludge-treated soils. (A
                previous study had shown a consistently
                significant difference in Cd uptake be-
                tween hybrids chosen as high- and low-
                Cd accumulators, but the  uptake  of Zn
                was not correlated closely with Cd up-
                take.)
                  Field plots of Blount soil  that had
                received annual sludge application  since
                1969 (with a high accumulation of 648
                mt/ha) were split and hand planted with
                two corn hybrids. Single-cross H99XW64A
                was a  low-Zn accumulator,  and
                A619XA632 was a high  one.  During
                1981, an additional  12.7  cm, or 36.5
                mt/ha of solids were applied as  liquid
                digested sludge  in furrows.  At the begin-
                ning of the Zn study, more than 2900 kg
Table 3.    Annual Digested Sludge Loading Rates and Total Accumulations on Maximum-
           Sludge- Treated Blount Silt Loam Plots Planted to Corn
                        Liquid Sludge Applied (cm)
                            Dry Solids Applied (mt/ha)
        Year
Annual
Accumulations
Annual
Accumulations
1968-1980
1981
10.2
253.3
263.5
31.8
733.3
765.1
Zn/ha had been applied on maximum-
sludge-treated plots, and an additional
105 kg Zn/ha was applied in 1981.
  Corn grain and stover yields indicate
that sludge applications increased grain
yields only in the hybrid selected for its
potential capacity to  take up small
amounts of Zn. But the hybrid selected for
its capacity to take up large amounts of Zn
produced higher grain yields at all rates
than did the low-Zn accumulator. Differ-
ences in stover yields were not significant
between the two hybrids. Concentrations
of Cu were increased more in the low-Zn
hybrid.
  Changes in Strip-Mine Spoil Character-
istics and Response of Plants to  High-
Rates of Sewage Sludge Application—
The purpose of this study  was (1) to
identify plants that  can be  established
quickly on strip-mine  spoils amended
with one large application of dried sludge,
and (2) to determine feasible one-time
loading rates for sludge.
  Air-dried sludge was applied in 1979 at
rates of 224,  448,  and 896 mt/ha on
replicated 21- x 18-m  plots. Big blue
stem, orchard grass, perennial ryegrass,
red top, reed canary grass, smooth brome,
tall fescue, timothy, and western wheat
grass were sown in 3- x 6-m subdivisions
of the large plot. Two additional plots (6- x
8-m) were planted with corn.
  Organic C and N  content of the spoil
declined only slightly during the 3-year
study,  indicating that the lagoon  sludge
used was very stable. Along with C and N,
total concentrations of P, Ca, Mg, Fe, Zn,
Cd, Cr, Cu, Ni, and Pb were significantly
increased in the spoil in proportion to
sludge loading rates. Little change was
indicated in soil properties below 30 cm,
except for a small pH change to a depth of
45 cm. Sludge applications increased the
concentration of N, Zn, Mn, Ni, Cd, and Cu
in corn plant tissues as they had in  the
first 2 years. Generally, sludge applica-
tions resulted in grasses enriched in Mg,
P, N, Zn, Ni, Cd, and Cu, but they did not
Table 4.   Amounts of Various Sludge Constituents Applied to Maximum-Treated Blount Silt Loam Plots Planted to Corn
Total
Annual mean
applied in
1981 (mg/L.
wet weight)
Total amount
applied
during 1968-81
(kg/ha, dry
weight)

Solids P K Na Ca Mg Fe Mn Cd Cu Cr Ni Pb Zn
3.14 890 232 104 1,012 468 1,500 6 5.7 48 72 15 22 94
23.589 3,997 - 25.269 9.725 33.305 344 191 1,067 2.259 279 790 3,748

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affect concentrations of Ca, Cr, and Pb.
The grasses that were easy to establish
and that produced the highest yields on
spoils treated with a high-rate loading of
dried sludge were tall fescue, reed canary,
orchard, and brome grass.

  Conclusions—After 14-years of apply-
ing digested sludge on Blount silt loam
soil (NW-800 series), no evidence  sug-
gested that a phytotoxic condition  was
imminent. Concentrations of Cd, Cu, Ni,
and Zn were consistently enhanced in the
leaf, grain, and stover of corn grown ofl
sludge-amended  plots,  but  there  was
little evidence that repeated annual appli-
cations  of these sludge-borne metals
significantly increased the accumulation
of these metals in the above-ground parts
of corn. The probable 'reason  is  that,
despite the continued addition of sludge,
metal levels in the soil did not increase.
Relative to the amounts of metals applied,
those migrating to depths below 30 cm
were negligible. Since erosion was also
negligible on these nearly level plots, it
appears that several sludge constituents,
including  transition and heavy metals,
were lost by unidentified processes either
before the sludge was incorproated into
the soil  or immediately thereafter.
  In a single season study, a single-cross
corn hybrid with an inherited capacity to
take up large amounts of zinc produced
higher grain yields and tended to accumu-
late less Cu in above-ground plant parts
than the low-Zn accumulator when grown
together on  maximum-sludge-treated
plots. This important finding needs  veri-
fication by repeating the experiment for
different soils and growing years.
  As  compared with sludges drawn di-
rectly from digesters,  digested sludge
dredged from storage lagoons contained
lower organic-C concentrations  and
higher metal contents. After sludge was
incorporated into calcareous  strip-mine
spoil, the initial increased organic-C and
metal contents in the 0- to 15-cm depth of
spoil  never decreased during the 3-year
study. Thus the organic matter remaining
in this  sludge was very resistant to
micrpbial decomposition in strip-mine
spoil. Corn growth on mine spoil amended
with high rates of this dewatered, stable
sludge  had  markedly  less  uptake of
sludge-borne Cd and Zn than did the
same corn hybrid grown on plots treated
with less stable sludge that was incre-
mentally applied  over several years on
similar  spoil material.  This  difference
occurred in spite of the fact that  total
concentrations of Cd and Zn were eight
times higher in the spoil amended with
the one-time,  high-rate sludge applica-
tion.

  Recommendations—The following rec-
ommendations are based on the findings
presented in this report:

  1.   Further  work should be  done to
      determine the pathways by which
      transition and heavy metals were
      lost when liquid digested sludge
      was repeatedly applied on soils for
      several years.
  2.   Further  work should be  done to
      determine whether or not the tran-
      sition and heavy metals remaining
      in soils will continue to be lost after
      sludge applications are terminated.
  3.   Further  work should be  done to
      determine why transition and heavy
      metals incorporated in  strip-mine
      spoil as constituents of a dewatered
      and very stable sludge (as judged by
      its organic-C contents) were not
      lost and were considerably less
      available for uptake by plants.
  4.   Further  work should be  done to
      select species and develop varieties
      of  grain and forage plants that
      would insure minimal  uptake of
      sludge-borne Cd, and maintain the
      potential for high yields  of crops
      with adequate concentrations of
      essential trace elements for ani-
      mals in  the plant parts  used as
      feedstuffs.

  The full reports were submitted in ful-
 fillment of Grant  No. R-805629  and
 Cooperative Agreement No.  CR-807780
 by the University of Illinois in cooperation
 with the Metropolitan Sanitary District of
 Greater Chicago under the sponsorship
 of  the  U.S.  Environmental  Protection
 Agency.
  *USGPO:  1984-759-102-10683

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      T. D. Hinesly. L G. Hansen, D. J. Bray. andK. E. Redborgare with the University of
        Illinois. Urbane, IL61801.
      G. K. Dotson is the EPA Project Officer (see below).
      This Project Summary covers two separate reports, entitled:
        "Long-Term Use of Sewage Sludge on Agricultural and Disturbed Lands,"
          (Order No. PB 84-224 427; Cost: $11.50)
        "Use of Sewage Sludge on Agricultural and Disturbed Lands," (Order No. PB
        84-224 419; Cost: $22.00)
      The above reports will be available only from: (cost subject to change
              National Technical Information Service
              5285 Port Royal Road
              Springfield. VA 22161
              Telephone: 703-487-4650
      The EPA Project Officer can be contacted at:
              Municipal Environmental Research Laboratory
              U.S. Environmental Protection Agency
              Cincinnati. OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300

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