See more from this Session: Management Impact On GHG Emissions and Soil C Sequestration: III
Wednesday, October 19, 2011
Henry Gonzalez Convention Center, Hall C, Street Level
Determining optimal rates of nitrogen (N) fertilization in corn-soybean systems is necessary to maximize production while protecting air and water quality. The production of greenhouse gases, particularly nitrous oxide (N2O), is a major environmental impact of corn-soybean production that has been shown to vary with N fertilization rates and cover cropping practices. However, previous studies have not found consistent relationships between these practices and N2O emissions. There is a need to clarify how basic carbon (C) and N cycling processes affect the relationships between fertilizer rate, cover cropping, and N2O emissions. We compared soil N2O and carbon dioxide (CO2) emissions and soil N cycling processes between a wide range of N application rates (0 to 224 kg/ha) with and without a winter rye cover crop in a no-till 2-yr corn-soybean rotation. Preliminary results show no differences in cumulative N2O fluxes between N fertilization rates of 135 and 224 kg N/ha, and no significant effect of cover cropping on N2O emissions. The results of this study contribute to quantifying the global warming impact of Midwestern corn-soybean agriculture.