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United States Department of Agriculture

Agricultural Research Service

Title: Natural Abundance Isotope Identification of Carbon in Earthworm Casts

item Linden, Dennis
item Clapp, Charles

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 3, 1996
Publication Date: N/A

Technical Abstract: The role of earthworms in the cycling of carbon from plant residues into soil organic matter has been known for eons. Soil organic matter is affected by the physical ingestion and translocation and by the mixing and enhanced microbial respiration which occurs within the earthworm gut. Casts from three common earthworm species Aporrectodea tuberculata, Lumbriscus rubellus, and Lumbriscus terrestris, which range from a small subsurface dweller and feeder to a large surface-feeder and deep-dweller, were collected periodically and frozen immediately for later analysis of total and isotope carbon. Individuals of each species were incubated in three soils ranging in carbon content between 1.5 to 3.0 percent. The earthworms were fed either corn or soybean residues for several weeks. Results indicate that fecal deposition carbon content can be doubled and the increase is related to the relative consumption of soil and residues and that the increased carbon in the worm casts is entirely due to fresh residue.

Last Modified: 4/17/2015