356-18 Does Earthworm Ecological Group Influence Gross Nitrogen Mineralization and Plant Uptake?.

Poster Number 210

See more from this Division: S03 Soil Biology & Biochemistry
See more from this Session: General Soil Biology & Biochemistry: II
Wednesday, October 19, 2011
Henry Gonzalez Convention Center, Hall C
Share |

Peter Tomlinson, Kansas State University, Manhattan, KS and Mary Savin, Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AR
Earthworm species from different ecological groups have different feeding strategies. Anecic earthworms incorporate plant residues from the surface into the mineral soil. Endogeic earthworms remain in the mineral soil, consuming organic matter. The objective of this study was to measure how these ecological strategies affect gross N mineralization of litter and subsequent plant N uptake. We hypothesized that earthworms of both ecological strategies would increase available N concentrations in soil. However, treatments with anecic earthworms were expected to have higher N mineralization and plant N uptake because of stimulation of decomposition with incorporation of new plant residue. In the laboratory, soil columns (PVC pipe 10-cm dia., 30-cm long) were filled with 20 cm of Captina silt loam. Endophyte (Neotyphodium coenophialum)-infected tall fescue (Lolium arundinaceum (Schreb) S. J. Darbysh) was grown and 15N-labeled endophyte-infected tall fescue litter was added to the soil surface of each respective treatment. Treatments included no worms, cores with two Diplocardia sp. (endogeic), cores with two Lumbricus terrestris (anecic), and cores with one each Diplocardia sp. and L. terrestris (mix). Total N and 15N atom% concentrations in litter, soil, earthworms, and plants were measured. Significantly more N from litter was recovered in the soil and earthworm tissue for the anecic and mix treatments than the endogeic and no worm treatments. Total N concentrations in the grass were not different among the treatments; however, less litter N was measured in the aboveground plant biomass in the anecic and mix treatments than the no worm treatment. Although anecic earthworms are incorporating litter into the soil, plants take up less N from decomposing litter than in the absence of earthworms. These results suggest that in the presence of earthworms relatively more plant uptake of N is a result of enhanced decomposition of soil organic matter.
See more from this Division: S03 Soil Biology & Biochemistry
See more from this Session: General Soil Biology & Biochemistry: II