Wd. Shuster et al., Foraging by deep-burrowing earthworms degrades surface soil structure of afluventic Hapludoll in Ohio, SOIL TILL R, 54(3-4), 2000, pp. 179-189
The presence of deep-burrowing earthworms can affect soil structure and inf
iltration, therefore influencing agricultural productivity. We investigated
the effects of deep-burrowing earthworm species on soil structure at the s
urface of chisel-plowed or ridge-tilled cropping systems in Pike County, OH
, planted to corn (Zea mays L.). Earthworm populations were experimentally
manipulated in field enclosures by adding predominantly deep-burrowing Lumb
ricus terrestris L., or leaving enclosures unmodified in each tillage syste
m. In 1995, after 2 years of hi-annual additions, we measured surface resid
ue cover, dry sieved aggregates (DSA)- and water-stable aggregates (WSA), a
nd carbon and nitrogen concentration of aggregates by size class, in each t
reatment combination. Also, in 1998, we used tension infiltrometry to exami
ne crusting effects at the soil surface among earthworm treatments in the c
hisel-plow treatment. Earthworm additions yielded increased density and bio
mass of L. terrestris than ambient controls, and to a greater extent in the
ridged corn-soybean (Glycine max L. Mess.)wheat (Triticum aestivum L.) (CS
W) than corn-soybean (CS) rotation. Percentage residue cover in CS cropping
decreased with earthworm additions. Earthworm additions decreased the geom
etric mean weight diameter (GMWD) of DSA and WSA in chisel-plow treatment c
ompared to no additions. Earthworm additions influenced 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. (C) 2000 Elsev
ier Science B.V. All rights reserved.