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 productivit y. Many Missouri soils are characterized by a claypan layer which can be a significant barrier to water infiltration and root penetration. O ur objective was to characterize the earthworms in these soils under v arious tillages, crop rotation, and nitrogen applications. The field s tudy has a split-split plot design with the tillage treatments (chisel -disk and no-till) as whole plots and rotation and nitrogen rates as s ubplots. The study's site had not been tilled for 3 years and the chis el-disk plots were tilled only 3 weeks prior to sampling. Crop rotatio n treatments were corn-soybean with continuous soybean and continuous corn as controls. Nitrogen rates were applied on randomly designated p lots at 112 or 224 kg N ha(-1). Individual plot size was 6.08 x 12.16 m with each plot replicated four times. Earthworms were handsorted fro m two 0.06 m(2) by 15 cm deep samples in each plot. Tillage was the si ngle 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 croppi ng or N treatment. The chisel tillage may have killed worms in the sur face 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 earthwo rms and any burrows present were minimally disturbed. Aporrecctodea tr apezoides was the most common species identified in this field with th e presence of unidentified native species. (C) 1997 Elsevier Science L td.