Earthworm response to rotation and tillage in a Missouri claypan soil

 Agricultural management practices affect earthworm populations. A field experiment was conducted to determine the effect of two rotations and two tillage systems on earthworm population density and biomass in a claypan soil. The rotations were soybean/corn and wheat/corn, and the tillage systems were conventional tillage (chisel plowed and disked) and no-tillage. Earthworm and soil samples were collected in fall 1995, spring 1996, and fall 1996. Aporrectodea trapezoides and Diplocardia singularis were the species identified at the site. A. trapezoides accounted for 92–96% of the total earthworm population density and D. singularis accounted for only 4–8%. In a no-till system, soybean/corn rotation resulted in significantly greater population density of A. trapezoides compared with the wheat/corn rotation. Crop residue quality (low C:N ratio) and quantity were important factors in increasing A. trapezoides population density and biomass. Conventional tillage markedly decreased population density and biomass of both earthworm species. Our results suggest that rotation and tillage significantly affect earthworm population density and biomass. Received: 6 June 1998