Evaluation of cover crop termination timing, soil nitrate availability and crop emergence
Date
2021
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Publisher
University of Delaware
Abstract
Implementing cover crops into farm management plans can prove to be an important tool in limiting nutrient leaching, providing a green manure nitrogen (N) source, preserving soil moisture and many other ecosystem services; however efforts are needed to understand the effect of management decisions on the cover crops overall performance and their effect on the cash crop’s yield and profitability. We assessed the effects of two termination timings on four cover crop treatments on a soybean cash crop at sites in northern and southern Delaware. Although cover crops appeared to have inconsistent effects on soybean yields, we did observe that control plots (no cover crop) had higher subsurface inorganic nitrogen, which demonstrated that any cover crop was better than none in preventing leaching from the surface. Lower levels of inorganic nitrogen was present in late terminated rye plots which indicated that it was best at scavenging for N. In terms of biomass production, late terminated clover/rye mix plots had the highest biomass, however late terminated vetch/rye mix plots had the highest N Mg ha-1. Plots with any legume mix were more successful at producing higher levels of N than monoculture rye plots. The vetch/rye mixture had a lower C:N, which may aid in supplying additional N through mineralization to the soybean cash crop. This work highlights the need to continue research on cover crop management techniques to provide insight on how to maximize the performance of cover crops to benefit yields and profitability for farmers.
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Keywords
Clover, Cover crops, Nitrogen, Rye, Termination, Vetch, Farm management plans