Papermill sludge enhances the quality of agricultural soils.

Full text

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FEB g 6 PAPERMILL
SLUDGE
ENHANCES
TRE
Otr1\Ll'TY
OF
AGRICULTURAL
SOILS
waste
sludge
from
_paperll!i~l;>
is
an
increasing
.source
of
landfill
disposal
costs
~n
Virg~n~a.
Dewatered
pape=~ll
sludge
from
wastewater
that
has
undergone
secondary
treatment
(i.e.,
enrichlllent
with
N
and
P
to
enhance
the
biological
digestion
process)
has
the
potential
to
be
a
valuable
soil
amendment
because
it
has
relatively
high
solids
content
and
nutrient
concentrations.
The
soluble
salts
are
largely
removed
in
the
dewatering
process,
which
further
enhances
the
value
of
this
material
as
a
soil
amendment.
l'n
addition,
the
high
concentration
of
cellulose
and
other
carbon
compounds
make
these
materials
attractive
as
amendments
for
increasing
the
organic
matter
content
of
the
highly
weathered
and
commonly
eroded
soils
of
the
southeastern
United
States.
Research
on
the
utilization
of
paper
mill
sludge
in
agriculture
(Dolar
et
al.,
1972;
Herll!an,
1972),
forestry
(Brockway,
1983;
Thacker,
1986),
and
land
reclamation
(Hoitink
and
Watson,
1982)
has
demonstrated
increased
plant
growth
and
yield,
soil
moisture
retention,
cation
exchange
capacity,
and
soil
nutrient
retention.
Adverse
effects
have
been
limited
to
high
soluble
salt
concentrations
and
N
deficiencies.
A
field
experiment
was
conducted
to
evaluate
the
use
of
a
dewatered,
semi-chemical
pulping
sludge
from
a
secondary
wastewater
treatment
process
as
a
beneficial
material
for
enhancing
soil
quality
and
to
investigate
the
potential
for
certification
of
the
material
as
a
soil
amendment
by
the
Virginia
Dep.
of
Agriculture
and
consumer
Services.
Materials
and
Methods
Sludge
and
soil
analysis
Samples
of
fresh.
dewatered
paperlllill
sludge
and
a
partially
composted
material
that
had
been
stockpiled
for
several
months
were
analyzed
for:
solids
content;
pH;
total
dissolved
solids
(TDS);
electrical
conductivity
(EC);
total
C;
total
Kjeldahl
N (TKN);
extractable
NH
4
-N
and
N03
-N;
total
P;
water
extractable-Ca,
Mg,
and
Na
and
sodium
adsorption
ratio;
Mehlich
!-extractable
P,
Ca,
Mg, K,
Mn,
Fe,
Zn,
cu,
B,
and
Al;
and
stability
based
on
reheating
potential
by
the
Dewar's
Flask
Method.
The
soil
was
analyzed
for
pH
and
Mehlich
I-extractable
P,
K,
Ca,
Mg,
Zn,
Mn,
Fe,
CU, B,
and
Al
by
the
Virginia
Cooperative
Extension
Soil
Testing
Laboratory
procedures;
cation
exchange
capacity
(CEC),
soil
c,
soil
N
and
water-holding
capacity
(WHC).
Land
application
A
replicated
plot
experiment
was
conducted
on
a
Wintergreen
clay
loam
(clayey,
kaolinitic,
mesic
Typic
Paleudults)
in
Amherst,
Virginia
to
test
different
combinations
of
sludge
and
N
fertilizer
for
corn
production.
Fresh
sludge
at
12.5
and
25
tons;acre,
aged
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sludge
at
12.5,
25,
and
50
tons/acre,
<:
a
non-sludged
control
each
received
N
(as
NH
4N03)
at
o,
75,
150,
..-.:1d
300
lbsjacre.
Each
of
the
24
treatJnent
coml:linations
was
rep..L.icated
4
times
in
a
randomized
complete
block
design.
Each
4-row
plot
was
14
ft.
wide
by
25
ft.
long.
A
long-term
tall
fescue
pasture
was
moldboard
plowed
and
disked
in
March
1995,
and
basal
applications
of
calcitic
limestone,
DAP,
and
muriate
of
potash
were
made.
Nitrogen
fertilizer
was
applied
on
May
15,
and
sludge
was
applied
with
a
front
loader
and
distributed
by
raking
the
next
day.
The
fertilizer
and
sludge
were
incorporated
into
the
soil
immediately
following
sludge
application
by
disking.
corn
(Pioneer
3394)
was
planted
on
May
17
at
a
target
rate
of
20,500
plants
per
acre.
Soil
was
sampled
by
coml:lining
12-1
ft.
deep
cores
per
plot
on
May
10
(prior
to
N
application),
Jt.:ne
21,
and
october
19
for
routine
soil
test
analysis.
Inorganic
;r
was
extracted
and
analyzed
from
the
soil
sampled
on
June
21.
·
r.ich
corresponds
to
the
recommended
soil
N0
3
-N
sampling
per~od
for
basing
sidedress
N
rates.
Corn
earleaf
samples
were
collected
at
silking
(July
19)
for
TKN
analysis.
Corn
grain
yields
were
estimated
by
harvesting
two
10
ft.
lengths
of
the
two
center
rows
of
each
plot
on
Septeml:ler
20,
weighing
the
shelled
grain,
and
adjusting
grain
moisture
to
15.St.
Results
and
Discussion
Sludge
and
soil
analysis
Analyses
of
the
papermill
sludge
are
presented
in
Table
1.
Elemental
concentrations
rose
by
2
to
4
times
as
fresh
sludge
decomposed
to
aged
sludge
due
to
loss
of
dry
matter.
The
high
total
carbon
(C)
concentration
and
C:N
ratio
of
the
fresh
sludge
relative
to
the
aged
sludge
shows
that
the
fresh
material
was
unstable
and
subject
to
considerable
further
decomposition,
and
aged
material
was
more
stable
but
not
completely
composted.
The
high
NH
4
-N
concentration
and
the
C:N
ratio
of
30:1
of
the
aged
material
demonstrated
that
the
sludge
requires
more
decomposition
to
attain
complete
stabilization
as
a
compost,
which
would
be
indicated
by
a
C:N
ratio
of
15-20:1.
The
self-heating
potential
of
the
aged
sludge
was
1s-2o•c
above
aml:lient
temperature,
which
is
comparable
to
that
of
a
finished
and
partly
cured
compost;
however,
the
C:N
ratio
of
30:1
is
indicative
of
an
immature
compost.
Saturated
paste
extractable
ca,
Mg,
and
Na
in
the
fresh
sludge
were
19.06,
2.88,
and
13.26
(ppm),
respectively,
which
resulted
in
a
sodium
3dsorption
ratio
of
0.75.
This
is
well
within
acceptable
limits
for
use
of
the
material
as
a
soil
medja
and
should
not
pose
any
soluble
salt-induced
problems
as
a
soil
anendment.
Apparently,
the
high
concentrations
of
Na
used
in
the
·:
··
-...,essing
is
largely
retained
in
the
dewatered
liquid
and
other
r
.1
••
,_{cling
processes.
Similarly,
EC
and
TDS
in
the
saturated
:::asc:a,
reflecti.::1ns
of

soluble
salt
concentrations,
were
safe
for
most
crops
at
1.67
dsjm
and
1070
ppm,
respectively.
Most
crops
will
survive
below
4.00
dsjm
and
few
crops
will
be
affected
by
an
EC
below
2.00
ds/m.
The
fresh
and
aged
sludge
contained
approximately
38%
and
45%
solids,
respectively.
Table
1.
Analysis
of
the
papermill
sludge
used
in
the
greenhouse
and
field
studies.
Sludge
~
Fresh
Aged
Fresh
Aged
Tot
org
.Ilili HIL.-N HQ3-N E
~
C:N
%
-----------ppm-----------
%
1.22
402
0.0
1305
50.6
41.5
1.28
1019
0.2
5534
38.6
30.1
Mehlich
I
extractable
~
E K Ca
~
~
~ ~
~
~
-----------------------ppm-----------------------
6.7
49
55
706
80
16
36
18
0.8
1.2
7.2
388
227
1989
258
41
126
62
1.5
2.7
Analyses
of
the
Wintergreen
soil
series
are
presented
in
Table
2.
The
soil
is
a
relatively
fertile
Piedmont
soil
that
had
a
total
c
concentration
of
1.8%
and
a
CEC
of
10.0
cmol(+)/kg.
Routine
soil
test
analysis
indicated
a
need
for
P
and
K
fertilization
and
liming.
Table
2.
Chemical
analysis
of
Wintergreen
series
used
in
greenhouse
and
field
studies.
Mehlich
I
extractable
Tot
~
E K
~
H9:
zn
Hn
~
cmol(+)/kg
--------------ppm--------------
5.7
10.0
2
64
348
109
1.3
5.3
1.8
Soil
results
(June>
Statistical
analysis
of
soil
test
results
for
individual
treatment
plots
prior
to
application
of
sludge
and
fertilizer
indicated
that
the
field
soil
was
uniform
with
respect
to
pH
and
elemental
analysis.
Soil
test
results
following
treatments
showed
that
aged
sludge
increased
the
concentrations
of
Al,
B,
Ca,
~.
Fe,
K, Mg, Mn,
P,
and
Zn
above
the
control
and
the
fresh
sludge.
There
were
no
differences
between
the
fresh
sludge
and
the
control
in
elemental
concentrations
or
pH,
except
B
was
higher
and
K
was
lower
with
the
fresh
sludge.
Soil
N03
-N
and
NH
4
-N
were
reduced
by
applications
of
both
sludge
types,
with
fresh
sludge
having
a
greater
effect
than
the
aged.
The
high
C:N
ratio
of
the
sludge
likely
caused
immobilization
of
soil
N,
and
greater
immobilization
was
achieved
with
the
less
stable
fresh
sludge.
Increasing
the
sludge
rate
(regardless
of
type)
increased
pH
and
the
concentrations
of
soil
Al,
B,
ca,
~.
Fe,
K, Mg, Mn,
P,
and

zn.
The
aged
sludge
was
more
effective
than
the
fresh
because
its
elemental
concentrations
were
greater.
soil
results
coctoberl
Soil
water-holding
capacity
at
6
in.
depth
was
increased
by
the
highest
sludge
rate,
which
indfcated
that
the
organic
water-holding
fraction
of
the
sludge
pers~sted
after
the
growing
season
(Table
3).
Soil
pH
was
increased
by
sludge
rate,
with
aged
material
more
effective
than
the
fresh
(Table
3).
These
results
demonstrate
the
ameliorative
effects
of
the
sludge-applied
organic
matter
and
basic
cations
on
soil
acidity.
Table
3.
Effect
of
sludge
type
and
rate
on
soil
pH
and
water-
holding
capacity
(WHC)
in
October,
1995.
Sludge
~
Control
Fresh
Aged
...mL
S.49c
S.66b
S.Sla
Sludge
rate
(tonsja)
0
12.S
2S
so
WHC
...mL
(%)
12.0a
S.49c
12.1a
S.64b
11.9a
S.84a
13.3b
S.82a
Soil
pH
and
WHC
values
within
the
same
column
followed
by
the
same
letter
are
not
significantly
different
at
the
0.
OS
level
of
probability
by
Duncan's
Multiple
Range
Test
{DMRT).
Soil
c
increased
more
with
application
of
the
aged
than
with
the
fresh
sludge
despite
the
higher
concentration
of
total
c
in
the
fresh
sludge
on
a
dry
weight
basis
(Table
4).
The
carbon
in
the
aged
sludge
was
probably
more
stable
than
the
C
in
the
fresh,
which
may
have
been
subject
to
further
mineralization
and
atmospheric
loss
as
C02• '
The
increase
in
soil
P
with
aged,
but
not
fresh,
sludge
rate
was
likely
due
to
the
higher
concentration
of
P
in
the
aged
material
{Table
4).
Microbial
immobilization
or
soil
fixation
of
P
may
have
contributed
to
lower
P
availability
from
fresh
sludge
because
N
treatments
increased
P
availability
from
the
aged,
but
not
fresh,
sludge.
Nitrogen
fertilizer
rate
was
the
only
treatment
that
affected
the
TKN
concentration
of
the
corn
earleaf
tissue,
which
showed
a
steady,
albeit
small,
increase
from
2.SO
to
'2.66
%N
as
the
N
rate
increased
from
o
to
22S
lbsja.
Neither
sludge
type
nor
rate
influenced
earleaf
N
concentration,
indicating
that
N
availability
was
not
affected
by
sludge
application.
6

Table
4.
Effect
of
sludge
type
%
rate
on
soil
C
and
P
in
october,
1995.
Sludge
~
(tons;
a)
0
12.5
25
so
Sludge
type
Fresh
~
soil
c (%)
l.Sa
2.
OSb
2.
20c
2.10bc
2.3Sd
2.9Se
Sludge
Fresh
Soil
P
6a
sa
6a
type
~
(ppm)
12b
22c
37d
soil
c
and
P
values
followed
by
the
same
letter
are
not
significantly
different
at
the
0.05
level
of
probability
by
DMRT.
Yields
were
increased
by
sludge
addition
in
the
order:
aged
sludge>
fresh
sludge>
control
(Table
5).
Fresh
sludge
increased
yield
through
the
addition
of
nutrients
and
organic
matter,
but
fresh
sludge
was
not
as
beneficial
as
aged
sludge
because
nutrient
concentrations
were
lower.
In
addition,
phytotoxic
compounds
in
the
fresh
sludge
decreased
germination
and
caused
visual
seedling
injury.
Increasing
sludge
rate
(regardless
of
sludge
type)
also
increased
corn
grain
yield,
with
the
50
t/a
rate
of
aged
sludge
resulting
in
the
highest
yield.
Therefore,
only
stabilized
sludge
should
be
applied
to
agricultural
land.
This
would
also
increase
the
value
of
the
sludge
by
concentrating
the
essential
plant
nutrients.
Table
s.
Corn
grain
yield
response
to
treatments.
Plant
Grain
:t:;z;:eatment
population
yield
plantsjacre
bujacre
~lydg~
type
Control
l6,367ab
84c
Fresh
15,64Sb
94b
Aged
16,979a
115a
~ludge
rate
(tons;
acre)
0
16,367
84c
12.5
16,406
104b
25
16,348
105b
50
16,719
122a
Plant
populations
and
grain
yields
followed
by
the
same
letter
are
not
significantly
different
for
sludge
rate
and
sludge
type
effects
at
the
0.05
level
of
probability
by
DMRT.
conclusions
Dewatered
papermill
sludge
is
a
potentially
valuable
soil
amendment
due
to
its
high
concentrations
of
organic
matter
and

nutrients.
However,
such
sludge
may
contain
phytotoxic
constituent(s)
in
its
fresh
state
and
possesses
N
immobilization
potential
due
to
its
relatively
high
C:N
ratio.
Aging
of
the
material
should
ameliorate
the
phytotoxic
properties
through
degradation
and
stabilization
of
the
organic
components.
Aged
sludge
may
increase
soil
pH,
soil
nutrient
concentrations,
and
water-holding
capacity.
A
papermill
sludge
that
exhibits
a
self-
heating
potential
of
less
than
20"C
rise
above
ambient
temperature
by
the
Dewar•
s
Flask
method
can
be
classified
as
a
stabilized
material
for
land
application
as
a
soil
amendment.
Literature
cited
Brockway,
o.G.
1983.
Forest
floor,
soil,
and
vegetation
responses
to
sludge
fertilization
in
red
and
white
pine
plantations.
J.
Soil
Sci.
Soc.
Am.
47:776-784.
Dolar,
S.G.,
J.R.
Boyle,
and
D.R.
Keeney.
1972.
Papermill
sludge
disposal
on
soils:
Effects
on
the
yield
and
mineral
nutrition
of
oats.
J
Environ.
Qual.
1:405-409.
Hermann,
D.J.
1982.
Considerations
for
using
wastewater
sludge
as
an
agricultural
and
silvicultural
soil
amendment.
P.
79-94.
In
C.A.
Rock
and
J.A.
Alexander
(ed.)
Long
range
disposal
alternatives
for
pulp
and
paper
ludges.
Univ.
Of
Maine,
Orono.
Hoitink,
H.A.J.,
and
M.E.
Watson.
1982.
Reclamation
of
acidic
stripmine
spoil
with
papermill
sludge.
P.
301-306.
In
E.M.
Seaker
and
R.K.
Bastian
(ed.)
Land
reclamation
and
biomass
production
with
municipal
wastewater
and
sludge.
Pennsylvania
State
Univ.
Press,
University
Park.
Thacker,
W.E.
1986.
Silviculture
land
application
of
wastewater
and
sludge
from
the
pulp
and
paper
industry.
P.
41-54.
In
o.w.
Cole,
et
al.
(ed.)
The
forest
'alternative
for
treatment
and
utilization
of
municipal
and
industrial
wastes.
Univ.
Of
Washington
Press,
Seattle.
Greg
Evanylo,
Extension
Soil
Scientist
and
Associate
Professor
Wasta
Management
and
soil
'
Water
Quality
w.
Lea
Daniels,
Associate
Professor
Disturbed
Land
Restoration
8