Earthworm activity in no-tillage and conventional tillage systems in Missouri soils: A preliminary study

Earthworms play a major role in overall soil fertility and productivity. Many Missouri soils are characterized by a claypan layer which can be a significant barrier to water infiltration and root penetration. Our objective was to characterize the earthworms in these soils under various tillages, crop rotation, and nitrogen applications. The field study has a split-split plot design with the tillage treatments (chisel-disk and no-till) as whole plots and rotation and nitrogen rates as subplots. The study's site had not been tilled for 3 years and the chisel-disk plots were tilled only 3 weeks prior to sampling. Crop rotation treatments were corn-soybean with continuous soybean and continuous corn as controls. Nitrogen rates were applied on randomly designated plots at 112 or 224 kg N ha−1. Individual plot size was 6.08 × 12.16 m with each plot replicated four times. Earthworms were handsorted from two 0.06 m2 by 15 cm deep samples in each plot. Tillage was the single most important factor influencing the number of earthworms in the spring and fall sampling. Greater numbers of earthworms were found in the no-tillage compared to the chisel-disk plots regardless of cropping or N treatment. The chisel tillage may have killed worms in the surface or caused the worms to move deeper in the soil profile. In the no-tillage plots, a greater source of food was available for the earthworms and any burrows present were minimally disturbed. Aporrecctodea trapezoides was the most common species identified in this field with the presence of unidentified native species.