Winter cover crops and no till management enhance enzyme activities in soybean field soils

Abstract

Elimination of tillage and planting winter cover crops are two conservation practices employed in agricultural row crop production to promote the accumulation of plant residues on the soil surface, improve soil structure, reduce erosion, and decrease losses of excess nutrients in runoff. The purpose of the current study was to assess the effects of no till management and two different cover crop species, Elbon rye (Secale cereal L.) and Crimson clover (Trifolium incarnatum L.), on microbial aspects of soil health, namely microbial biomass and enzyme activities (phosphatase, β-glucosidase, N-acetylglucosaminidase, and fluorescein diacetate [FDA] hydrolysis) in order to determine potential impacts on the size and nutrient cycling capabilities of microbial communities in lower Mississippi Delta soybean (Glycine max L.) field soils over a three-year period. Microbial biomass in surface soil was elevated under no till and both cover crop treatments. Soil enzyme activities associated with organic matter breakdown were increased by cover crop more than tillage, while phosphatase and FDA hydrolysis were increased by both. The higher activities due to cover crop input appear to be the result of an enlarged microbial community as well as increased substrate availability. While these enhanced soil biological traits did not translate into higher soybean yields, longer evaluation periods may be necessary to fully appreciate the benefits of improved soil health in crop production systems.