Earthworm Populations in a Wheat-Soybean Double-Crop System Under Six Years of Established Residue Management Practices.

Earthworms improve soil structure, distribute litter and microbes, stimulate microbial activity, facilitate decomposition, and increase nitrogen (N) availability for plant growth. Earthworm abundance is often reduced in low organic matter soils that are intensively managed to grow row crops. This study was designed to relate earthworm abundance and community composition to residue management after six years of established management practices in experimental wheat-soybean double crop system plots maintained in Marianna, AR.  Residue management practices used in this study include conventional tillage v. no-till, high versus low wheat residue left in the field, and burning versus not burning after harvest.  Average number of earthworms across all treatments ranged from 81 to 200 m^-2 for adults and 281 to 522 m^-2 for total abundances.  Both exotic and native adult earthworms were present with very little diversity among any of the sampled communities: however, more than 50 percent of adults were natives in all but one of the twenty-four plots.  Worm numbers were not linearly related to soil pH, electrical conductivity, or organic matter concentration.  Little current research exists regarding how earthworm populations and abundances respond to different residue management practices in wheat-soybean double-crop systems, and very little current research exists on identifications of Arkansas earthworms.