Directory UMM :Data Elmu:jurnal:S:Soil & Tillage Research:Vol54.Issue3-4.Apr2000:
Soil & Tillage Research 54 (2000) 179±189
Foraging by deep-burrowing earthworms degrades surface
soil structure of a ¯uventic Hapludoll in Ohio
W.D. Shustera, S. Sublerb, E.L. McCoya,*
b
a
School of Natural Resources, The Ohio State University, OARDC, Wooster, OH 44691, USA
Soil Ecology Laboratory, Department of Entomology, The Ohio State University, Columbus, OH 43210, USA
Received 11 December 1998; received in revised form 24 September 1999; accepted 10 January 2000
Abstract
The presence of deep-burrowing earthworms can affect soil structure and in®ltration, therefore in¯uencing agricultural
productivity. We investigated the effects of deep-burrowing earthworm species on soil structure at the surface of chisel-plowed
or ridge-tilled cropping systems in Pike County, OH, planted to corn (Zea mays L.). Earthworm populations were
experimentally manipulated in ®eld enclosures by adding predominantly deep-burrowing Lumbricus terrestris L., or leaving
enclosures unmodi®ed in each tillage system. In 1995, after 2 years of bi-annual additions, we measured surface residue cover,
dry sieved aggregates (DSA)- and water-stable aggregates (WSA), and carbon and nitrogen concentration of aggregates by
size class, in each treatment combination. Also, in 1998, we used tension in®ltrometry to examine crusting effects at the soil
surface among earthworm treatments in the chisel-plow treatment. Earthworm additions yielded increased density and
biomass of L. terrestris than ambient controls, and to a greater extent in the ridged corn±soybean (Glycine max L. Mess.)±
wheat (Triticum aestivum L.) (CSW) than corn±soybean (CS) rotation. Percentage residue cover in CS cropping decreased
with earthworm additions. Earthworm additions decreased the geometric mean weight diameter (GMWD) of DSA and WSA
in chisel-plow treatment compared to no additions. Earthworm additions in¯uenced carbon-to-nitrogen (C/N) ratios for
smaller DSA and WSA. Water-stable aggregate C/N decreased with size class. The overall effect of earthworm additions was
an increase in deep-burrowing earthworms, a decrease in surface residue cover, and more pronounced crusting, which
decreased mesopore conductivity. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: Soil aggregation; Earthworms; Crop residue; Crusting; Carbon
1. Introduction
Earthworms comprise a major proportion of the
total invertebrate biomass in temperate, terrestrial
ecosystems (Edwards and Bohlen, 1996), and can
*
Corresponding author. Tel.: 1-330-263-3884; fax: 1-330263-3658.
E-mail address: [email protected] (E.L. McCoy)
in¯uence soil chemical, biological, and physical processes. In this study, we address the possibility that
certain earthworm species may impact on surface soil
aggregation, with implications for surface crusting
and subsequent erosion.
Earthworms have been observed to increase the
number and water stability of macroaggregates, and
improve in®ltration (Mackay and Kladivko, 1985;
Blanchart, 1994; Ketterings et al., 1997). Historically,
0167-1987/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 1 6 7 - 1 9 8 7 ( 0 0 ) 0 0 0 9 4 - 5
180
W.D. Shuster et al. / Soil & Tillage Research 54 (2000) 179±189
the presence of earthworms is associated with
improvements in, rather than degradation, of soil tilth
and cropping conditions. The anecic species Lumbricus terrestris L. is active at the soil surface where it
forages, and below the surface where burrows extend
the earthworm's in¯uence deep into the soil pro®le.
Anecic earthworms have been shown to affect soil
structure by foraging (Shaw and Pawluk, 1986), burrowing (Pitkanen and Nuutinen, 1997), and casting
(Shipitalo and Protz, 1988). By foraging and creating
middens, deep-burrowing earthworms change the spatial distribution of coarse organic matter at the soil
surface (Shaw and Pawluk, 1986; Gallagher and Wollenhaupt, 1997; Pitkanen and Nuutinen, 1997; Willoughby et al., 1997). Moreover, in a corn cropping
system, Subler and Kirsch (1998) found that 96% of
total coarse organic matter in surface soil present after
the fall corn harvest was concentrated around earthworm middens by the early spring.
Middens are highly localized patches of soil, casts,
and coarse organic matter in various stages of processing. As foraging activities proceed, earthworms can
decrease the area of soil surface protected by residual
coarse organic matter. Without residue cover, the soil
surface is vulnerable to degradation by increased
exposure to weathering (Freebairn et al., 1991) and
may form surface crusts or seals. Also, earthworms
can process organic matter, producing unique byproducts like burrow linings and casts which contain
temporary or transient aggregate binding compounds
(Tisdall et al., 1978; Shaw and Pawluk, 1986). These
carbon compounds can bind soil particles together,
thereby reducing the effects of water slaking and
inhibiting crust formation. Therefore, given appropriate organic matter resources, earthworms can in¯uence
soil aggregation. However, another effect of residue
consolidation is to increase the spatial heterogeneity
of carbon resources at the soil surface and within the
soil matrix. Yet, earthworm foraging activities result
in a patchy distribution of the organic resources necessary for the production of carbonaceous transient
binding agents (Tisdall et al., 1978). This could limit
the availability of these binding agents at small spatial
scales, and would therefore in¯uence the formation of
soil aggregates that are resistant to slaking. The consequencesoforganicmatterforagingbydeep-burrowing
earthworms could include the exposure of a considerable amount of soil surface area to increased weathering.
The conditions under which deep-burrowing earthworm species contribute to the improvement or degradation of surface soil structure are not well
understood, nor widely studied. The purpose of this
study was to assess earthworm effects on formation of
surface crusts. We measured the size-distribution,
stability and carbon and nitrogen concentrations of
soil aggregates, and unsaturated hydraulic conductivity of crusted and non-crusted surfaces. These measures were analyzed for indications of whether
earthworm additions have the potential to change soil
structure in row-crop production systems typical to the
midwestern US.
2. Materials and methods
2.1. Soil, climate and cropping systems
The study site was located at the Ohio Management
Systems Evaluation Area (MSEA) (Ward et al., 1994)
near Piketon, OH (398020 N, 838020 W). Soils at this
¯ood plain site are predominantly Huntington silt
loam (US taxonomy: ®ne-silty, mixed, mesic ¯uventic
Hapludoll; FAO classi®cation: Haplic Chernozem),
with landscape slopes ranging between 2 and 5%.
A typical particle-size analysis of these soils yield
210 g kgÿ1 sand (50±2000 mm), 550 g kgÿ1 silt (2±
50 mm), and 240 g kgÿ1 clay (F
p>F
Earthworm
Crust
Earthworm crust
0.09
Foraging by deep-burrowing earthworms degrades surface
soil structure of a ¯uventic Hapludoll in Ohio
W.D. Shustera, S. Sublerb, E.L. McCoya,*
b
a
School of Natural Resources, The Ohio State University, OARDC, Wooster, OH 44691, USA
Soil Ecology Laboratory, Department of Entomology, The Ohio State University, Columbus, OH 43210, USA
Received 11 December 1998; received in revised form 24 September 1999; accepted 10 January 2000
Abstract
The presence of deep-burrowing earthworms can affect soil structure and in®ltration, therefore in¯uencing agricultural
productivity. We investigated the effects of deep-burrowing earthworm species on soil structure at the surface of chisel-plowed
or ridge-tilled cropping systems in Pike County, OH, planted to corn (Zea mays L.). Earthworm populations were
experimentally manipulated in ®eld enclosures by adding predominantly deep-burrowing Lumbricus terrestris L., or leaving
enclosures unmodi®ed in each tillage system. In 1995, after 2 years of bi-annual additions, we measured surface residue cover,
dry sieved aggregates (DSA)- and water-stable aggregates (WSA), and carbon and nitrogen concentration of aggregates by
size class, in each treatment combination. Also, in 1998, we used tension in®ltrometry to examine crusting effects at the soil
surface among earthworm treatments in the chisel-plow treatment. Earthworm additions yielded increased density and
biomass of L. terrestris than ambient controls, and to a greater extent in the ridged corn±soybean (Glycine max L. Mess.)±
wheat (Triticum aestivum L.) (CSW) than corn±soybean (CS) rotation. Percentage residue cover in CS cropping decreased
with earthworm additions. Earthworm additions decreased the geometric mean weight diameter (GMWD) of DSA and WSA
in chisel-plow treatment compared to no additions. Earthworm additions in¯uenced carbon-to-nitrogen (C/N) ratios for
smaller DSA and WSA. Water-stable aggregate C/N decreased with size class. The overall effect of earthworm additions was
an increase in deep-burrowing earthworms, a decrease in surface residue cover, and more pronounced crusting, which
decreased mesopore conductivity. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: Soil aggregation; Earthworms; Crop residue; Crusting; Carbon
1. Introduction
Earthworms comprise a major proportion of the
total invertebrate biomass in temperate, terrestrial
ecosystems (Edwards and Bohlen, 1996), and can
*
Corresponding author. Tel.: 1-330-263-3884; fax: 1-330263-3658.
E-mail address: [email protected] (E.L. McCoy)
in¯uence soil chemical, biological, and physical processes. In this study, we address the possibility that
certain earthworm species may impact on surface soil
aggregation, with implications for surface crusting
and subsequent erosion.
Earthworms have been observed to increase the
number and water stability of macroaggregates, and
improve in®ltration (Mackay and Kladivko, 1985;
Blanchart, 1994; Ketterings et al., 1997). Historically,
0167-1987/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 1 6 7 - 1 9 8 7 ( 0 0 ) 0 0 0 9 4 - 5
180
W.D. Shuster et al. / Soil & Tillage Research 54 (2000) 179±189
the presence of earthworms is associated with
improvements in, rather than degradation, of soil tilth
and cropping conditions. The anecic species Lumbricus terrestris L. is active at the soil surface where it
forages, and below the surface where burrows extend
the earthworm's in¯uence deep into the soil pro®le.
Anecic earthworms have been shown to affect soil
structure by foraging (Shaw and Pawluk, 1986), burrowing (Pitkanen and Nuutinen, 1997), and casting
(Shipitalo and Protz, 1988). By foraging and creating
middens, deep-burrowing earthworms change the spatial distribution of coarse organic matter at the soil
surface (Shaw and Pawluk, 1986; Gallagher and Wollenhaupt, 1997; Pitkanen and Nuutinen, 1997; Willoughby et al., 1997). Moreover, in a corn cropping
system, Subler and Kirsch (1998) found that 96% of
total coarse organic matter in surface soil present after
the fall corn harvest was concentrated around earthworm middens by the early spring.
Middens are highly localized patches of soil, casts,
and coarse organic matter in various stages of processing. As foraging activities proceed, earthworms can
decrease the area of soil surface protected by residual
coarse organic matter. Without residue cover, the soil
surface is vulnerable to degradation by increased
exposure to weathering (Freebairn et al., 1991) and
may form surface crusts or seals. Also, earthworms
can process organic matter, producing unique byproducts like burrow linings and casts which contain
temporary or transient aggregate binding compounds
(Tisdall et al., 1978; Shaw and Pawluk, 1986). These
carbon compounds can bind soil particles together,
thereby reducing the effects of water slaking and
inhibiting crust formation. Therefore, given appropriate organic matter resources, earthworms can in¯uence
soil aggregation. However, another effect of residue
consolidation is to increase the spatial heterogeneity
of carbon resources at the soil surface and within the
soil matrix. Yet, earthworm foraging activities result
in a patchy distribution of the organic resources necessary for the production of carbonaceous transient
binding agents (Tisdall et al., 1978). This could limit
the availability of these binding agents at small spatial
scales, and would therefore in¯uence the formation of
soil aggregates that are resistant to slaking. The consequencesoforganicmatterforagingbydeep-burrowing
earthworms could include the exposure of a considerable amount of soil surface area to increased weathering.
The conditions under which deep-burrowing earthworm species contribute to the improvement or degradation of surface soil structure are not well
understood, nor widely studied. The purpose of this
study was to assess earthworm effects on formation of
surface crusts. We measured the size-distribution,
stability and carbon and nitrogen concentrations of
soil aggregates, and unsaturated hydraulic conductivity of crusted and non-crusted surfaces. These measures were analyzed for indications of whether
earthworm additions have the potential to change soil
structure in row-crop production systems typical to the
midwestern US.
2. Materials and methods
2.1. Soil, climate and cropping systems
The study site was located at the Ohio Management
Systems Evaluation Area (MSEA) (Ward et al., 1994)
near Piketon, OH (398020 N, 838020 W). Soils at this
¯ood plain site are predominantly Huntington silt
loam (US taxonomy: ®ne-silty, mixed, mesic ¯uventic
Hapludoll; FAO classi®cation: Haplic Chernozem),
with landscape slopes ranging between 2 and 5%.
A typical particle-size analysis of these soils yield
210 g kgÿ1 sand (50±2000 mm), 550 g kgÿ1 silt (2±
50 mm), and 240 g kgÿ1 clay (F
p>F
Earthworm
Crust
Earthworm crust
0.09