Submitted to: Natural Organic Matter in Soils and Water North Central Region Symposium
Publication Type: Proceedings
Publication Acceptance Date: 12/1/2003
Publication Date: N/A
Technical Abstract: Maintaining crop production and long-term environmental quality requires effective residue and fertilizer management. The objective was to verify the capability of the NCSWAP/NCSOIL model to simulate the dynamics of N and N15 in the soil-plant system. A long-term continuous corn (Zea mays L.) study was initiated in 1980, after a long history of low input pasture and hay, at Rosemount, MN. Conventional tillage (CT) plots with two levels of application rates (20 and 200 kg N/ha) and two types of residue management (residue removed, -R; and residue returned, +R) were used to calibrate the model. A sensitivity analysis was carried out for 30 years. The model accurately predicted N15 in the soil organic matter (SOM) at 0- to 15-cm depth for both fertilizer rates and residue managements. For the same amount of N15 added (8 kg N15/ha), concentrations of N15 in the corn and SOM were higher for the 20 than 200 kg N/ha treatments. The predicted cumulative N lost during 12-years simulation indicates more NO3 leaching to below 1m-depth for -R than +R plots, while higher denitrification rates were predicted for the +R than -R. These results are analyzed in terms of the simulated C and N dynamics.