We investigated the population dynamics and vertical distributions of microbes and several soil faunal groups for 2 years in field Andosols in northeastern Japan. The experimental plots were under no-tillage (NT) and conventional tillage (CT) management. Although bacterial and fungal substrate-induced respiration (SIR) in the 0-10 cm soil layer were both higher under NT than under CT, the populations of soil fauna in this soil layer did not differ significantly except for enchytraeids, which were more abundant under NT. In contrast, both SIR values were higher in the 10-20 cm layer under CT, where larger populations of protozoa, free-living nematodes, mites, and collembola were recorded. Thus, negative impacts of tillage on soil micro- and mesofauna appeared to be small in this type of soil. The development of more sophisticated tillage techniques is necessary in organic cropping to preserve soil biota and use the beneficial functions of the detritus food web.
Soil biota; Soil ecology; Tillage.