313-4 Nitrous Oxide Emissions From a No-till Corn-Soybean Rotation Comparing N Fertilization and Cover Cropping Treatments.



Wednesday, October 19, 2011
Henry Gonzalez Convention Center, Hall C, Street Level

David C. Mitchell, Michael J. Castellano, John E. Sawyer, Fernando Miguez and Jose L. Pantoja, Department of Agronomy, Iowa State University, Ames, IA
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.
See more from this Division: ASA Section: Environmental Quality
See more from this Session: Management Impact On GHG Emissions and Soil C Sequestration: III