Management and Implications of Cover Crops in No-till Corn and Soybean Systems in Nebraska.

Nebraska’s unique climate and growing season limit cover cropping, however Nebraska farmers are interested in winter cover cropping in corn-soybean systems. In this four-year project, we explored 5 different cover crop treatments, planted either early or late into corn or soybean at 4 locations along a temperature and precipitation gradient in Nebraska. Cover crop productivity and quality, changes in soil chemical and physical properties, impacts on crop yields and overall profitability of the farming system were measured. Rye and mixes containing rye were the most productive cover crops, but productivity was highly variable, as low as 0.07 Mg ha^-1 at one location in 2015 and 4.8 Mg ha^-1 at another location in 2016. High cover crop biomass production was correlated with reductions in main crop yields in several site years. Rye reduced soil nitrate in the spring, and legumes did not change soil nitrate in most site years compared to a control. Crop yield reductions may be due to cover crop water uptake or cover crop residue quality. Research findings will help Nebraska growers decide on whether to implement cover crops in corn-soybean systems.