Significance of litter layer in enhancing mesofaunal abundance and microbial biomass nitrogen in sweet corn-white clover living mulch systems

Living mulch is a type of sustainable farming system that consists of cover crops planted either before or with a main crop; a living mulch is maintained as a living ground cover throughout the growing season of the main crop. Microbial biomass and abundance of mesofauna (microarthropods and enchytraeids) are important soil biological parameters in relation to soil function, plant productivity, and nutrient cycling; however, the effects of living mulch on these parameters are not fully understood. In this study we examined the effects of living mulch treatment with nitrogen fertilizer (0, 40, 160, or 200 kg ha−1) on the abundance of soil microarthropods (Oribatida, Mesostigmata, Prostigmata, and Collembola) and the effects of living mulch treatment on the dynamics of the soil biota (mesofauna, microarthropods, enchytraeids, and microbial biomass nitrogen) from spring to autumn. Our results showed that living mulch treatment significantly (p < 0.05) increased the grain weight of the main crop in both experiments. Generally, living mulch treatment had a positive effect on the abundance of mesofauna and microbial biomass nitrogen, despite pesticide usage. Nitrogen levels did not affect the number of microarthropods. The litter layer in living mulch significantly (p < 0.05) enhanced microbial biomass nitrogen and the abundance of Oribatida, Prostigmata, and Collembola. We conclude that living mulch enhances mesofaunal abundance and microbial biomass nitrogen and that the production of a litter layer by living mulch is one of the major mechanisms for this enhancement.