Simulated effects of tillage and timing of N fertilizer application on net greenhouse gas fluxes and N losses for agricultural soils in the Midwestern USA

摘要

The DAYCENT ecosystem model was used to simulate net greenhouse gas emissions (GHG_(net)), N gas losses, and N leaching for corn and corn/soybean rotations in the Midwestern USA. The effects of tillage and timing of fertilizer application on GHG_(net) and N losses were calculated for clay loam and sandy loam soils. N_2O emissions, CH_4 uptake, changes in soil organic carbon (SOC), and the CO_2 costs of N fertilizer production were converted to a common unit of CO_2-C equivalents and summed to obtain GHG_(net). GHG_(net) and grain yields were higher for the finer textured soil while total N gas losses and leached N were higher for the coarser soil. Conversion to no-till increased soil organic carbon substantially, but also led to slightly lower crop yields and higher N leaching. Split application of fertilizer increased crop yields and SOC and decreased N losses from leaching and N gas fluxes.