Carbon and nitrogen release from cover crop residues and implications for cropping systems management

Abstract

Cover cropping is an effective management practice for reducing nitrogen (N) losses to the environment from agriculture fields in the Upper Mississippi River Basin (UMRB). Cereal rye (CR; Secale cereale L.) and hairy vetch (HV; Vicia villosa Roth) are two of the most common cover crop species grown in the UMRB. Few studies have examined the effect of corn (Zea mays L.) or soybean (Glycine max L.) management on the rate and timing of N and carbon (C) release from CR and HV residue. The objective of this study was to measure the effect of cash crop rotation (continuous corn, corn–soybean, and soybean–corn), cover crop selection (CR, HV, and a CR/HV mixture), and tillage (spring disk or transitional no-till) on the rate and timing of N and C loss from litterbags as an estimate of N and C release from cover crop residue. Our results demonstrated that rotation did not impact cover crop N and C release. However, HV released both N and C at rates 2.1 and 1.6 times faster, respectively, than treatments that included CR. Furthermore, where residue was incorporated, rates of N and C release were 2.7 and 3.0 times faster, respectively, than where residue was not incorporated. When averaged across cover crop species and tillage, 17% to 56% of nutrient release occurred, after planting, during vegetative cash crop growth stages. Results from this study advanced the understanding of how cropping systems management can influence release of N and C from cover crop residue.