Agronomic, Environmental and Economic Benefits of Site Specific Nitrogen Management for Maize (Zea mays L.).

Assessments of nitrogen management strategies for maize (Zea Mays L.) should be comprehensive. Such assessments must include agronomic, environmental and economical metrics to appeal to different stakeholders. In this two-year field-scale study, we compared conventional nitrogen management based on economical optimum nitrogen rate (EONR) to site-specific N management (SSNM) based on in-season crop sensing. Comparisons were made based on improvement in nitrogen use efficiency (NUE), grower’s return on investment (ROI) and nitrogen pollution reduction in tile drainage. Eight sub-fields in southern Minnesota were planted maize in two consecutive years following soybeans and maize. Each sub-field is tile-drained and monitored individually for nitrate leachate. SSNM consisted of 50kg N ha^-1 applied pre-plant and the remaining nitrogen applied at maize growth stage V8 using a spinner box guided with a VRT controller. Drainage samples were collected weekly the entire growing season and analyzed for nitrates allowing for flow-weighted concentrations. At the end of this multi-season field experiment, this research will answer not only the economic impact of SSNM, but more importantly its environmental and agronomic benefits