Influence of Cover Crop Species on Enzyme Activity and Nitrogen Supply at Critical Corn Growth Stages.

Cover crop adoption in the Midwest Corn Belt region is a rapidly emerging adaptive management practice being used as a tool to reduce nitrate loading from tile-drainage. However, little is known about the inclusion of cover crops on the soil microbial community and their efficiency in facilitating nitrogen release from cover crop residue. Therefore, the primary goal of this study was to determine the impact of cover crop species on the release of nitrogen from cover crop residue and the soil and litter enzyme dynamics within no-tillage and spring tillage corn (Zea mays L.) production systems. Results indicate that β-glucosidase activity in cover crop litter decreased over the growing season, while urease activity in the litter peaked in early August and remained stable until R6. Soil inorganic N trended greater from the V6 to R2 growth stages in the spring tillage cover crop treatments compared to the spring tillage no cover crop control. It was also observed that soil urease and β-glucosidase activity were related to an increase in soil temperature leading up to the V6 and R6 growth stages, respectively. Soil β-glucosidase activity at the V6 growth stage was significantly greater for cereal rye (Secale cereal L.) dominated treatments relative to hairy vetch (Vicia villosa Roth) treatments, but was similar to the control (p<.05). Additionally, soil β-glucosidase activity peaked at the V6 growth stage and was related to the peak of plant available nitrogen. Data generated from this study leads to a deeper understanding of growing season N dynamics in cover cropped corn agroecosystems, and helped determine the opportune dates to further examine the soil microbiome through next-generation sequencing methods.