Optimizing cover crop management for biomass production and potential of weed suppression

Abstract

International audienceCover crops have been identified as an efficient tool in non-chemical weed management strategies. Cover crops suppress weeds mainly by competing with them for resources. High production of biomass limits the access of weeds to light and thus reduces their growth. However, cover crop biomass depends on seeding rate, date and termination timing. This study was conducted in seven location (five states) in the Northeastern United States and replicated 3 years. Hairy vetch (Vicia villosa Roth), an annual legume, which is one of the most commonly utilized species due to its cold hardiness, was planted at two dates in autumn and at rates of 6 to 50 kg ha-1. The cover crop was terminated in the next spring at the stages of early, intermediate vegetative, and 50% flowering. Cover crop biomass was mainly determined by the total growing degree days (GDD) between planting and termination and increased by 529 kg.ha-1 every 100 GDD. A nonlinear model (asymptotic regression through the origin) was used to fit the biomass data as a function of the seeding rate. The model included two parameters: asym was the asymptote (i.e., the maximum biomass when seeding rate approaches infinity); lrc was the natural log of the rate constant, representing how quickly the asymptote was reached. Only 3 out of 80 data sets (4%) could not be fitted to the model. Contour plots provided a visual demonstration of the interactions between seeding rate and seeding dates on hairy vetch biomass by termination timing. Thus, the study identified how much seeding rate needed to be increased when seeding date was delayed to maintain a given biomass production