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Compost Effects on Soil Physical
Properties And Field Nursery Production
R.F. Gonzaleza & L.R. Cooperbandb
a Graduate student, Guapiles, Costa Rica
b Department of Soil Science, University of Wisconsin, Madison,
Wisconsin
Published online: 23 Jul 2013.
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Properties And Field Nursery Production, Compost Science & Utilization, 10:3, 226-237, DOI:
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Compost Science & Utilization, (2002), Vol. 10, No. 3, 226-237
Compost Effects on Soil Physical Properties
And Field Nursery Production
R.F. Gonzalez1 and L.R. Cooperband2
1. Graduate student, Guapiles, Costa Rica
2. Department of Soil Science, University of Wisconsin, Madison, Wisconsin
Field production of ornamental shrubs often results in significant topsoil removal and
degradation of surface soil physical properties. Building soil organic matter through
compost amendments is one way to ameliorate effects from topsoil removal in woody
ornamentals production. We amended field soils with three composts to evaluate
their effects on soil physical properties and shrub biomass production. Specifically,
we applied either duck manure-sawdust (DM), potato cull-sawdust-dairy manure
(PC) or paper mill sludge-bark (PMB) composts to a Plano silt loam soil using two ap-
plication methods: 2.5 cm of compost incorporated into the top 15 cm of soil (incor-
porated-only) or 2.5 cm of compost incorporated plus 2.5 cm of compost applied over
the soil surface (mulched). We grew three shrub species from liners: Spirea japonicum
‘Gumball’, Juniper chinensis ‘Pfitzeriana’, and Berberis thunbergia ‘Atropurpurea’.
Shrub species and soil amendment treatments were established in triplicate in a ran-
domized split plot design. Total soil carbon (TC), bulk density (ꢀb), aggregate stabil-
ity, soil moisture retention capacity (MRC), volumetric moisture content (ꢁ ), and sat-
v
urated hydraulic conductivity (K ) were measured over three years (1998 to 2000).
sat
We measured above and below ground shrub dry matter production at the end of the
first (1998) and second (1999) growing seasons. Mulched treatments resulted in 15%-
21% higher TC than the incorporated-only and no-amendment control treatments.
Bulk density decreased with increasing TC contents. Greater aggregate stability and
the formation of larger aggregates were related to increased TC. Field moisture re-
tention capacity tended to be higher in the incorporated treatments compared to the
mulched and nonamended control treatments. Compost amended treatments in-
creased saturated hydraulic conductivity (K ) sevenfold over the nonamended con-
sat
trol. There were no compost effects on shrub biomass until the second year of growth.
Barberry was the only species to respond significantly and positively to compost ap-
plication. Specifically, mulched DM compost produced 39-42% greater total Barber-
ry biomass than the other compost treatments and the nonamended control. Our find-
ings showed that compost effects on soil physical properties differed among
composts and their subsequent effects on shrub growth were species specific.
Introduction
Field production of ornamental shrubs often results in significant topsoil removal
when the shrubs are harvested. Topsoil removal usually results in soil organic matter
(SOM) declines over time. The reduction of SOM has a negative effect on soil physical
properties, including water retention capacity, plant available water, aggregation, in-
filtration and drainage (Stevenson 1994). Use of composts derived from wood and tim-
ber by-products along with animal manures or food processing wastes holds promise
as an environmentally and economically sound means of rebuilding SOM in orna-
mental horticulture systems.
Most of the research related to compost use with ornamental horticultural crops
has been conducted either under greenhouse conditions or in containerized systems
in the field. Although very different from field soil, container systems provide valu-
able insights about how compost application might affect soil physical properties and
226 Compost Science & Utilization
Summer 2002

Compost Effects on Soil Physical Properties and Field Nursery Production
plant growth. For example, Tripepi et al. (1996) found that amending sandy soil-based
container mixes with increasing amounts of composted paper mill sludge decreased
mix bulk density and increased waster holding capacity in a linear fashion. In contrast,
Atiyeh et al. (2001) found that pig manure vermicompost amended to a horticultural
bedding medium increased bulk density and decreased total porosity, while it in-
creased container (water holding) capacity. These findings suggest that compost ef-
fects on soil physical properties will differ among compost types.
Field studies using compost in horticultural crop production have demonstrated
beneficial effects on crop growth in the short term. Gouin and Walker (1977) found that
stem length of Liriodendron tulipifera L. and Cornus florida L. seedlings was greater in
sewage sludge compost-amended plots. Robbins et al. (1986) doubled prune yields in
a 13-year old Italian prune (Prunus domestica L.) orchard after a single compost appli-
cation. Maynard (1998) showed that compost applied as both a soil amendment and
mulch reduced first-year mortality of Acer sp. relative to the nonamended control.
Stuckey and Hudak (2001) demonstrated that compost application to loblolly pine (Pi-
nus taeda) trees produced higher soil moisture, higher survival rates, and greater
growth increases than the control group.
These studies provide evidence for the beneficial effects of compost application on
soil physical properties and plant growth. However, we found no studies evaluating
compost effects on soil properties in horticultural production systems that remove
large amounts of topsoil; i.e., field production of ornamental shrubs. Additionally, we
found very few studies that identified those soil properties most responsible for orna-
mental plant growth. The objectives of this study were (i) evaluate effects of different
compost types and application methods on soil physical properties in field shrub pro-
duction; (ii) to quantify compost effects on ornamental shrub growth and (iii) to eval-
uate relationships between soil physical properties and shrub growth.
Materials and Methods
Site Description and Experimental Design
The experiment was conducted at the University of Wisconsin West Madison Agri-
cultural Research Station between May 1998 and September 2000. The experimental
site is located at 43°5’ N and 89°31’ W. The predominant soil type is Plano silt loam,
fine silty, mixed, mesic, Typic Argiudoll (U.S. Soil Taxonomy), and the field has less
o
than 2 slope. Baseline soil characteristics were measured prior to compost application
(Table 1). The experimental design was a randomized split plot with shrub species as
the main effect and compost type and application method as the secondary effects. The
experimental design consisted of:
• Three shrub species: Spirea japonicum ‘Gumball’ (Spirea), Juniper chinensis
‘Pfitzeriana’ (Juniper), and Berberis thunbergia ‘Atropurpurea’ (Barberry).
• Three compost types: duck manure-sawdust, potato cull-dairy manure-sawdust,
and paper mill sludge-bark.
• Three application methods and rates:
ꢀ Incorporated only = 2.5 cm layer of compost incorporated into the top
15 cm of the topsoil (low rate).
ꢀ Mulched = 2.5 cm incorporated plus 2.5 cm layer of surface applied
compost (high rate).
ꢀ No amendment control.
Compost Science & Utilization
Summer 2002 227

R.F. Gonzalez and L.R. Cooperband
TABLE 1.
Baseline chemical properties of study soil.
Standard
Deviation
†
Property
Units
Mean
-1
NH -N (2 M KCL)
4
NO -N (2 M KCL)
3
pH (sat. paste)
mg L
mg L
–
11.6
15.6
7.1
1.1
2.3
0.1
5.8
60.1
53.7
34.2
0.1
0.01
–
-1
-1
-1
-1
-1
Bray-1 P
mg kg
mg kg
mg kg
mg kg
%
46.3
Exch. K (1 M Ammon. Acetate)
Exch. Ca (1 M Ammon. Acetate)
Exch. Mg (1 M Ammon. Acetate)
TC (Dry combustion CHN)
TN (Dry combustion CHN)
DTPA-Zn
316.7
1633.3
685.8
2.2
%
0.22
-1
-1
-1
-1
-1
-1
mg kg
mg kg
mg kg
mg kg
mg kg
mg kg
<0.04
33.5
DTPA-B
23.5
8.0
45.2
–
DTPA-Mn
84.1
DTPA-Fe
135.8
<0.01
4.6
DTPA-Cu
DTPA-Al
2.5
†
n= 15 samples (5 reps X 3 blocks) collected prior to compost application, May 1998.
Treatments were replicated three times in plots of 2.1 m x 1.2 m. Within each
“whole plot” (plant species), there were seven soil treatments: (three compost types x
two methods of application) + control.
Compost Material and Application
Duck manure compost (DM) and potato cull (PC) composts were produced at the
University of Wisconsin’s West Madison Agricultural Research Station. The raw ma-
terials used for the duck manure compost were duck manure (excreta +wood shavings
bedding) and sawdust in a volumetric ratio of 1:1. For the potato cull compost we
mixed potato culls, sawdust and dairy manure in a volumetric ratio of 3:3:1. The pa-
per mill sludge-bark (PMB) compost was obtained from Renewed Earth, Inc. (Kala-
mazoo, Michigan). The raw materials used for this compost were paper mill sludge
and bark, in a volumetric ratio of 1:1.
All composts were produced using open-air turned windrow composting meth-
ods. Duck manure and PC compost were composted for eight months, whereas PMB
compost was composted for five months. We evaluated compost chemical properties
prior to field application (Table 2). There were differences in total carbon, C:N ratios
and available nutrients.
TABLE 2.
Chemical characterization of compost materials at time of application to soil (May 1998).
‡
¶
C:N TN
TC§ Ash
P
g kg
K
Ca
Mg
S
Zn
B
Mn
mg kg
Fe Cu
-1
Na pH EC
†
-1
-1
Compost Type
S m
DM
PC
17.5 22
12.9 16
19.7 17
385 222 9.33 15.4 27.4 6.1 2.9 317 22.3 480 3209 45.3 1553 8.1 0.095
206 424 4.00 17.3 21.0 8.8 2.2
338 197 2.28 3.2 43.9 4.1 4.1
67
95
3.0 406 7998 15.2 755 8.4 0.130
6.4 906 3744 16.9 870 7.9 0.035
PMB
†
DM =Duck manure-sawdust compost; PC = potato Cull-sawdust-dairy manure compost; PMB = Paper mill residuals-
‡
§
Bark compost. TN = total nitrogen (determined using dry combustion). TC = total carbon (determined using dry
combustion). EC = electrical conductivity
¶
228 Compost Science & Utilization
Summer 2002

Compost Effects on Soil Physical Properties and Field Nursery Production
Composts were applied to plots on a volume basis. Incorporated only compost
3
-1
3
-1
plots received 254 m ha and mulched compost plots received 508 m ha . On aver-
age, the total amount of carbon (C) added to the incorporated only compost plots was
-1
-1
11.4 Mg ha , and 22.79 Mg ha was added to the mulched plots. We incorporated com-
posts into the top 15 cm of soil two weeks prior to planting. Mulched compost treat-
ments did not receive the mulch layer until two months after planting to allow time
for seedling establishment.
Planting
We planted 18 rooted vegetative cuttings (liners) per plot on a 0.3 m x 0.3 m spac-
ing. The liners were approximately 15 to 18 cm tall, and were inserted vertically in 15-
cm deep holes. We also planted a grass strip (0.5 m wide) between each plot to mini-
mize soil erosion and water movement of compost among plots. During the first
growing season, Juniper seedlings were supported with 20-cm long stakes.
Plot Maintenance
Plants were manually watered biweekly (1 cm of water each time) at the beginning
of the experiment, and after planting through July 1998. Weeds were removed from
each plot through hoeing. The grass in the vegetative strips was mowed every two to
three weeks.
No commercial fertilizers were added to the soil during the experiment. In Sep-
tember 1998, we thinned the planting density from 18 plants to nine plants per plot
2
(2.52 m ) by destructive harvest (aboveground and belowground plant sections).
Soil Measurements
Unless specified differently in each method description, we collected nine
cores for each of the seven soil treatments (3 blocks ꢂ 3 plant species) for soil mea-
surements requiring intact soil cores. For soil measurements using a disturbed soil
sample, we collected one composite soil sample per plot consisting of at least 10
sub samples, 15 cm soil depth. In all cases, we removed the mulch layer prior to
sampling.
Total Soil Organic Carbon
Total soil organic carbon (TC) was measured prior to compost application (base-
line; May, 1998), six months after compost application (October 1998) and two years
after compost application (May 2000). Soil samples were air-dried and ground with
a Nasco-Asplin soil grinder (Nasco, Fort Atkinson, Wisconsin) to pass through a 2-
mm sieve. Samples were further ground manually with a mortar and pestle to pass
through a 1-mm sieve to homogenize the sample and to increase the accuracy of the
analysis. Total soil carbon in the baseline soil samples was determined with a total
CHN analyzer (Carlo Erba, 1500-Na, Italy). Postcompost application TC was deter-
mined using a combustion total carbon analyzer (DC-190, Rosemount Analytical
Inc., Santa Clara, California). Baseline TC content was remeasured with the DC-190
combustion total carbon analyzer, to compare the results with those that had been
previously obtained with the total carbon-nitrogen analyzer.
Compost Science & Utilization
Summer 2002 229

R.F. Gonzalez and L.R. Cooperband
Soil Bulk Density and Porosity
We measured soil bulk density in the top 7.6 cm of the soil profile for three con-
secutive years prior to and after compost application (May, 1998; June 1999; and June
2000). We collected soil cores using a double-cylinder, hammer-driven core sampler
3
(345-cm metal core; 7.6 cm long ꢂ 7.6 cm inner diameter) (Blake and Hartge, 1986).
The soil samples were placed in an oven at 105° C until achieving constant weight.
The soil bulk density was calculated as the oven-dry mass of the soil sample divid-
ed by the core volume. Soil porosity was calculated from the soil bulk density using
the equation,
% Porosity = 1-(soil bulk density/particle density) ꢂ 100
-3
where particle density was assumed to be 2650 kg m .
Aggregate Stability
We measured aggregate stability at the end of the experiment (Spring 2000), using
a modified procedure for wet sieving (Kemper and Rosenau 1986). We collected soil
samples from the top 7.5 cm of the soil profile using a 20-cm diameter metal ring. We
selected a subset of plots for a total of four cores per compost treatment. Since we were
most interested in compost type/rate effects, we used Barberry plots only, because its
small root biomass was expected to have minimal impact on soil structure. When the
soil was still moist, soil samples were gently sieved through an 8-mm screen. Soil ag-
gregates <8 mm in diameter were air-dried for approximately 24 hours. For each air-
dried sample of sieved soil aggregates, we prepared three 25.0-gram sub samples for
further analysis. These sub samples were placed on a nest of sieves (2.0, 1.0, 0.5, and
0.25-mm opening sieves) and then rewetted slowly using a spray bottle.
We used a wet sieving machine (stroke length of 1.3 cm and frequency of 35 cycles
-1
minute ) with the ability to sieve six nests of sieves simultaneously. The samples were
immersed in distilled water for 10 minutes and then gently agitated for another ten
minutes. The soil remaining in each sieve was collected and oven-dried (105˚ C) to de-
termine dry mass.
After wet sieving, each sample was dispersed in a sodium hexametaphosphate so-
-1
lution (2 g L ), and then manually re-sieved until only sand particles were left on the
sieve. The sand from each sieve was collected, oven-dried and weighed. The oven-
dried mass of aggregates per sieve was calculated by subtracting the mass of sand from
the oven-dried mass of soil remaining in each sieve. Aggregate stability was charac-
terized as the distribution of aggregate mass in a range of size classes.
Soil Moisture Retention
Soil moisture retention in the saturated to field capacity range was determined
annually using intact cores (May 1998; May 1999; and May 2000). Soil cores were sat-
urated with tap water for 24 hours. Once saturated, we placed the samples in a low
-1
matric potential range system (0 to approximately -20 J kg ) and determined volu-
-1
metric soil moisture contents at matric potentials between 0 and -25 J kg . We used
an apparatus similar to that used by McGuire and Lowery (1994). Soil moisture re-
lease curves were constructed by plotting the volumetric moisture content against
-1
matric potentials. Volumetric moisture content at -33 J kg was estimated from the
soil water release curves.
230 Compost Science & Utilization
Summer 2002

Compost Effects on Soil Physical Properties and Field Nursery Production
Soil Moisture Content
Gravimetric soil water content was measured biweekly during the growing sea-
son in 1998 and 1999. Composite samples (0-15 cm depth) were oven dried (105° C) un-
til constant weight was achieved. Bulk density was used to convert gravimetric water
content to volumetric water content.
Saturated Soil Hydraulic Conductivity
Saturated soil hydraulic conductivity (K ) was measured on intact soil cores
sat
(May 1999 and May 2000) using the falling head method (Klute and Dirksen 1986).
Soil cores were saturated with a 0.005 M CaSO , 0.1% phenol, CO –free solution for
4
2
24 hours. To prevent preferential flow of water along the core wall, a thin layer of soil
(≈ 1 mm) along the top edge of the sample was replaced with bentonite clay. Soil cores
were placed under a water column, and the change in the water head per change in
time was measured. The saturated soil hydraulic conductivity (K ) was calculated
sat
using the following equation;
K
= [aL/A (t –t )](log H - log H ),
2 1 1 2
sat
where a is the cross-sectional area of the water column, L is the length of the soil sam-
ple, A is the cross-sectional area of the soil sample, and t – t , and log H – log H , cor-
2
1
1
2
respond to the change in time and change in the water column height, respectively.
Plant Dry Matter Production
In September 1998 and 1999, we harvested five plants per plot (45 plants per treat-
ment or 5 plants ꢂ 3 species ꢂ 3 blocks) for dry matter (biomass) determinations. At
the end of the second growing season (1999) seven Barberry plots were not harvested
because of infection with Fusarium sp. Aboveground plant biomass included stems and
foliage. Each shrub was harvested by cutting the stem at the soil surface. To harvest
the belowground (root) biomass, we used a 18-cm long metal core with an inner di-
ameter of 15 cm. Once the aboveground biomass was removed, we placed the core over
the remaining stem so that it was in the center of the core. The core was driven into the
soil to a depth of approximately 18 cm using a sliding weight. To avoid severe dam-
age of secondary roots, soil was carefully removed from plant roots by rinsing them
with tap water.
Aboveground plant parts were also carefully washed with tap water to remove
any soil particles. Both aboveground and belowground plant parts were oven dried at
®
60° C until constant weight was achieved (Delta Range PR2003 analytical balance,
Mettler-Toledo, Switzerland). The aboveground and belowground dry masses were
combined to obtain the total plant dry mass production.
Statistical Analysis
The SAS Version 8 “Plot” procedure (SAS Institute, Cary, North Carolina) was ap-
plied to identify outliers and test the normality of our data. We used the SAS “Mixed”
procedure to conduct an analysis of variance to determine plant species and compost type
and/or application method effects on soil properties. We used the same procedure to de-
termine compost effects on shrub biomass production. We performed an analysis of co-
variance to identify the soil physical variables that had significant effects on plant growth.
Compost Science & Utilization
Summer 2002 231

R.F. Gonzalez and L.R. Cooperband
Results and Discussion
Statistical analyses revealed that there was an interaction between shrub species
and compost treatments. For many of the physical properties measured, we found sig-
nificant compost effects on soil physical properties only in plots with Barberry. As
such, we focus our presentation of soil physical results using data from Barberry plots
only. If there were significant compost effects on soil physical properties with other
shrub species, they are included and noted in the results.
Total Soil Carbon
Total soil carbon contents (TC) of all compost-amended treatments remained
significantly higher than the no-amendment control up to two years after compost
application (Figure 1; p < 0.005). Nonetheless, TC contents declined from July 1999
to May 2000 among all compost types. All mulched treatments lost approximately
twice as much TC as the incorporated-only treatments; however the decomposition
rates were similar since twice as much C was added with mulched treatments com-
pared to incorporated-only treatments. During the three years of study (1998 –
-1
2000), all mulched treatments maintained 2.7-4 g kg more TC than the incorporat-
ed-only treatments (P< 0.015). The DM compost maintained the highest TC contents
among compost types. This
was likely related to the
higher C added with the DM
compost material.
Other studies have shown
similar effects with single or-
ganic amendment applica-
tions. Lindsay and Logan
(1998) applied anaerobically
digested sewage sludge to a
Miamian silt loam and ob-
served an increasing linear re-
lationship between TC and
sludge application rate. In
contrast, Zibilske et al. (2000)
tested five rates of paper mill
sludge and found that soil TC
increased only with the high-
est sludge application rates.
Figure 1. Compost treatment effects on total soil carbon. Barberry plots
only. DM= duck manure compost; PC= potato cull compost; PMB= pa-
per mill sludge-bark compost. 1= 2.5 cm-layer compost incorporated
into top 15 cm of soil; 2= 2.5 cm incorporated + 2.5 cm applied as
mulch. Treatment by date interactions with the same letter are not sig-
nificantly different (a= 0.05).
Bulk Density and Porosity
During the first year after compost application there was no significant compost
effect on soil ꢀb (P= 0.42). Others have found that amendment effects on ꢀb take more
than one year to manifest themselves, particularly in fine textured soils (Zibilske et al.,
2000). Bulk density was significantly lower (P<0.05) in the mulched treatments during
1999 and 2000, among all plant species (Table 3). The mulched DM compost treatment
had the lowest ꢀb among all treatments.
During the second and third year after compost application, ꢀb was significantly
lower in Spirea and Barberry plots compared to Juniper plots. The significantly greater
232 Compost Science & Utilization
Summer 2002

Compost Effects on Soil Physical Properties and Field Nursery Production
TABLE 3.
Compost treatments effects on soil bulk density in Barberry plots
during 1999 and 2000.
ꢀb
1999
ꢀb
1999
ꢀb
2000
ꢀb
2000
Incorporated-only
Mulched
Incorporated-only
Mulched
-3
-3
-3
-3
Compost Type
(Mg m
)
(Mg m
)
(Mg m
)
(Mg m
1.13 c
)
Duck manure
Potato cull
1.38
1.40
1.40
1.37
1.26
1.34
1.37
1.37
1.24 a
1.25 a
1.21 ab
1.24 a
1.18 abc
1.16 bc
1.24 a
Paper mill sludge-bark
Control
There were no significant differences among compost types and application methods during 1999 (a= 0.1). Data points
corresponding to year 2000 with the same letter are not significantly different (a = 0.05). Within a given compost type,
data points with the same letter are not significantly different (a= 0.05).
root systems of Spirea (54.63
g) and Barberry (24.21 g) rel-
ative to Juniper (8.26 g) might
have displaced mineral soil
particles with higher particle
density, thereby lowering
overall soil bulk density. Al-
ternatively, greater root bio-
mass and production of root
exudates could have in-
creased soil aggregation,
which could have decreased
ꢀb (Zibilske et al., 2000).
In general, mulched
treatments resulted in higher
soil porosity (Figure 2). Two
years after compost applica-
Figure 2. 1999-2000 compost application method/rate effects on total soil
porosity averaged over compost types. Barberry plots only. Bars with the
tion (May 2000), mulched
same letters are not significantly different (a=0.05).
treatments of DM and PMB
composts produced signifi-
cantly higher soil porosity relative to the no-amendment control (p< 0.038). Since
porosity is derived from bulk density, we invoke a similar explanation for the mulch
effect on porosity; increased aggregation resulted in increased total pore space
(Martens and Frankenberger 1992).
Aggregate Stability
Soil aggregate stability increased with increasing TC contents. Mulched treat-
ments increased the mass fraction of 5-, 1.5-, and 0.75-mm soil aggregate size class-
es relative to the incorporated-only treatments and the no-amendment control (Fig-
ure 3). Concurrently, the mass fractions of 0.375- and 0.125-mm soil aggregate size
classes were lower in the mulched treatments compared to the incorporated-only
treatments and no-amendment control. Our findings corroborate those of other stud-
ies involving organic amendment applications to soils (Guerrero et al. 2000;
Chantigny et al. 1999). Lindsay and Logan (1998) also reported significant increases
in percent water stable aggregates with increasing biosolids application rate. Zi-
Compost Science & Utilization
Summer 2002 233

R.F. Gonzalez and L.R. Cooperband
bilske et al. (2000) observed
that aggregation increased
with increasing sludge C ad-
dition for the 2- and 1-mm
size fractions, while it
stayed the same in the 0.25-
mm fraction.
Soil Moisture Retention
We compared moisture
retention for the low-tension
range of the curve only (sat-
urated to field capacity con-
ditions). One year after com-
post application (1999), the
DM-compost amended soils
had higher water retention
compared to PC- and PMB-
compost amended soils and
in the no-amendment con-
trol soil (Figure 4). When
evaluating the relationship
between TC and estimated
volumetric water content at
Figure 3. Compost application method effects (averaged across compost
types) on aggregate size distribution two years after compost application
(spring 2000). Bars within an aggregate size class with the same letter are
not significantly different (a=0.05).
field capacity (ꢁ ), there
v33
was a significant inverse re-
lationship between ꢁ
and
v33
2
TC content (r =0.40; p=
0.0007). The addition of DM
compost promoted the for-
mation of slightly larger
pores relative to PC and
PMB composts. This could
have allowed soil water re-
lease at lower energies and
lowered soil water retention
Figure 4. Soil moisture retention curves of compost-amended soils from
-1
saturation to field capacity (0-20 -J kg ). PMB= paper mill-bark compost;
DM= duck manure compost; PC= potato cull compost.
in the low-tension range of the moisture retention curve. Wei et al. (1985) also ob-
served that water retention decreased for the sludge-treated soils at water potentials
-1
≥ -33J kg . They highlighted that this was a positive effect on a silty clay loam soil,
since this soil has very poor drainage.
Volumetric Moisture Content Under Field Conditions
During the first growing season (1998) among all shrub species, field-measured
3
volumetric soil moisture content (ꢁ ) was higher in the mulched treatments (0.264 m
v
-3
3
-3
m ; mean of all dates) than in the incorporated-only treatments (0.235 m m ; mean
3
-3
of all dates) and the no-amendment control (0.242 m m ; mean of all dates) (p=0.059).
Epstein et al. (1976) and Wei et al. (1985) reported similar findings with the application
of sludge and compost. Compost treatment differences disappeared in the second
234 Compost Science & Utilization
Summer 2002

Compost Effects on Soil Physical Properties and Field Nursery Production
growing season (1999). Compost decomposition and reduction of the mulch layer may
have reduced the amendment effect on ꢁ . Nonetheless, ꢁ was approximately 4% low-
v
v
er in the no-amendment control compared to compost-amended treatments.
Our findings suggest that the effect of organic amendments on moisture retention
and volumetric water content differed depending on the moisture status of the soil. In
-1
the wet end of the soil moisture release curve (≥ -33 J kg ), higher TC resulted in low-
er water retention and lower volumetric water content. When the soil dried and reached
-1
higher soil water potentials (≈ -766 J kg ), higher TC corresponded to greater ꢁ . The
v
net result was an evening out of the soil’s moisture status with addition of compost.
Saturated Soil Hydraulic Conductivity
There was no significant treatment effect on saturated soil hydraulic conduc-
tivity during the first growing season (1998). One year later, the conductivity rate
K
was two to eight times higher in all
sat
TABLE 4.
the amended treatments compared to
the nonamended control (Table 4).
These findings were similar to those of
Wei et al. (1985) and might have been
related formation of larger and more
stable aggregates. Two years after
compost application (spring 2000),
Compost effects on saturated hydraulic
conductivity (K ).
sat
1999
2000†
-1
-3
-1
-3
Treatment
cm sec ꢂ 10
cm sec ꢂ 10
DM-1
PC-1
8.96
5.99
10.7
4.40
17.6
11.3
2.73
a
a
a
a
a
a
b
2.22
5.34
8.86
4.81
4.99
5.37
2.89
there was still a trend of higher K in
PMB-1
DM-2
PC-2
sat
compost-treated plots relative to con-
trol plots, but it was not statistically
significant. Loss of organic carbon
from compost-amended plots likely
weakened the compost effect on aggre-
gation and hence, saturated hydraulic
conductivity.
PMB-2
Control
DM= duck manure; PC= potato cull; PMB= paper mill-
bark composts. 1= incorporated only; 2= incorporated +
mulched. † No significant treatment differences in 2000.
Compost Effects on Shrub Biomass Production
There were no significant compost type or application method effects on biomass
production across plant species during the first growing season (Table 5; p< 0.42). De-
spite the positive effects of compost application on soil physical properties, they did
not translate to short-term effects on shrub growth. Other studies with woody plants
have shown similar delays in plant response to compost application. Typically, woody
plants respond two to three years after compost application (Robbins et al. 1986).
The only significant effect of compost on plant growth during the second growing
season was for the duck manure compost mulch treatment on Barberry. None of the
other treatments had a significant (Table 5; P< 0.1) effect on growth of any of the
species. Root biomass production was not significantly affected by compost applica-
tion method (P= 0.25); however, root biomass was 11% higher in the mulched treat-
ments than in the no-amendment control. The root: shoot ratio in the mulched treat-
ment of DM compost was 27% lower than in the other treatments, which suggests that
root growth in the mulched treatment of DM compost was less likely to be under
drought stress, soil compaction or poor soil aeration, thus, favoring shoot growth.
Studies of woody ornamentals in container production have shown plant species-spe-
cific responses to compost (Chong et al. 1994; Hoitink et al. 1997). Maynard (1998) also
Compost Science & Utilization
Summer 2002 235

R.F. Gonzalez and L.R. Cooperband
TABLE 5.
Barberry’s root, shoot and total biomass production and root/shoot ratio during
first and second growing seasons.
Compost
Type
Application
Method
Root
Biomass
Shoot
Biomass
Plant
Biomass
Root/shoot
Ratio
†
1998
g
Duck manure compost
Duck manure compost
Potato cull compost
Potato cull compost
Paper mill sludge-bark
Paper mill sludge-bark
No-amendment control
Incorporated-only
Mulched
5.69
6.30
7.56
5.33
4.63
7.57
5.41
14.86
14.16
14.22
15.07
10.82
16.60
12.18
NS
20.55
20.46
21.77
20.40
15.45
24.16
17.59
NS
0.38
0.45
0.53
0.35
0.43
0.46
0.45
Incorporated-only
Mulched
Incorporated-only
Mulched
‡
NS
§
1999
Duck manure compost
Duck manure compost
Potato cull compost
Potato cull compost
Paper mill sludge-bark
Paper mill sludge-bark
No-amendment control
†
Incorporated-only
Mulched
26.30 b
31.84 b
¶
116.41 b
221.55 a
¶
142.72 b
253.39 a
¶
0.23
0.14
¶
Incorporated-only
Mulched
21.24 b
23.61 b
23.06 b
24.43 b
125.93 b
126.64 b
129.60 b
130.98 b
147.17 b
150.24 b
152.65 b
155.41 b
0.17
0.19
0.18
0.19
Incorporated-only
Mulched
‡
§
Plant biomass = (Root + Shoot biomass) NS = Not significant. For 1999, data points within a given biotype with the
same letter are not significantly different (□= 0.1). Lower case letters correspond to treatment comparisons. Capital letters
¶
indicate compost type comparisons. Missing data due to Fusarium sp. infestation. Biomass production by application
method was calculated with DM and PMB data only.
found species-specific benefits of compost use and different responses to different ap-
plication rates in a field trial using MSW-biosolids compost in shade tree production.
In conclusion, the compost treatments had measurable beneficial effects on soil
physical properties, but those improvements did not translate into statistically sig-
nificant benefits for plant growth, except for Barberry. Among the composts used,
mulched duck manure compost had the greatest beneficial effect on Barberry
growth. It may be that physical properties were not limiting plant growth in a two-
year growing cycle (e.g., Spirea is considered a very fast growing species and toler-
ant of “poor” soils). Alternatively it is possible that the shrubs like Juniper exempli-
fy species whose growth is too slow to respond to changes in soil physical properties
over the short term.
Acknowledgements
We wish to thank the crew of the University of Wisconsin, West Madison Agricul-
tural Research Station and Tom Wright (Superintendent) for their assistance with com-
posting and field plot maintenance. We thank Dr. Alex Stone (Asst. Professor, Oregon
State University) for her assistance with experimental design and experiment estab-
lishment. We appreciate the donation of shrub liners from McKay Nursery (Waterloo,
Wisconsin) and the input on experimental design and shrub evaluation from Bernie
Fourrier, (Vice President, McKay Nursery). We thank Brian Foley, Joe Ravet, Mike Fry-
da, Vicente Garcia and Kris Niemann for their assistance with field work and laborato-
ry analyses. This research was funded by a grant from the U.S. Federal Hatch program.
236 Compost Science & Utilization
Summer 2002

Compost Effects on Soil Physical Properties and Field Nursery Production
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