- Agronomic: clovers, corn, rye
- Crop Production: cover crops, nutrient management
Sustainable cereal production systems rely on healthy soils and biologically based nitrogen. Previous research has shown that grass-legume cover crop mixtures can provide soil conservation benefits while also increasing the plant available nitrogen to a subsequent corn (Zea mays L.) crop. However, our understanding of the multifunctional benefits of cover crop mixtures is based largely on research conducted in uniform, plot-scale settings that are not representative of farmers' fields. Rolling-hill landscapes make up a large portion of farmland in the Southeastern United States and present a challenge for grain crop producers in the region because they possess areas of high soil fertility interspersed with regions of low fertility. We hypothesize that grass-legume cover crop mixtures will reduce this spatial variability. In particular, we hypothesize that a legume species will dominate, add more nitrogen, and release nitrogen more quickly in lower-fertility sloping positions, whereas grass species will dominate, scavenge nitrogen, and release it more slowly in higher-fertility summit and depressional positions. We propose to test these hypotheses using a field experiment at two on-farm locations and two research farm locations. We plan to measure the biomass, species composition, nitrogen fixation, and nitrogen release of grass/legume cover crop mixtures at different landscape positions. Knowledge about cover crop effects on soil nitrogen supply gained from this research will benefit farmers in the region and contribute to a more economically and ecologically sustainable attitude towards managing cropland in rolling hill landscapes.
Project objectives from proposal:
- Quantify the biomass production and species composition of cereal rye-crimson clover cover crop mixtures as compared to cereal rye monocultures and winter fallow at different landscape positions.
- Quantify the amount of nitrogen taken up from the soil nitrogen pool and produced through symbiotic nitrogen fixation by a cereal rye-crimson clover winter cover crop mixture at different landscape positions.
- Quantify the rates of decomposition of a cereal rye winter cover crop and a cereal rye-crimson clover winter cover crop mixture at different positions throughout the landscape under a corn cash crop.