Assessment of Enhanced Efficiency Fertilizers and Application Timing Interactions on Nitrate Leaching in Corn (Zea Mays L.).

Globally, nitrate (NO_3­­­^-) leaching is a concern because it has negative environmental and health consequences through groundwater contamination. The largest source of NO_3­­­^- groundwater contamination is the conventional use of nitrogen (N) fertilizers in agriculture. However, NO_3­­­^- leaching in agriculture may be reduced with enhanced efficiency fertilizers (EEFs) by synchronizing the availability of NO_3­­­^- with crop N demand. A field study was initiated to evaluate the influence of N management practices (N product and timing combinations) on NO_3­­­^- leaching in corn production systems. Measurements were collected in four farm-scale plots (~4 ha) within a larger homogeneous plot (~30 ha) that is in the same experimental area as a larger study on N₂O emissions. Study plots received the recommended fertilizer treatment rate of 150 kg N ha^-1 differing by timing of N application and product. Two plots received fertilizer treatments at planting as urea and urea + urease and nitrification inhibitors. Additionally, two plots received fertilizer treatments at the 6^th leaf stage as UAN and UAN + urease and nitrification inhibitors. NO_3­­­^- concentrations were measured using porous ceramic cup samplers installed at 9 locations in each plot at a depth of 80 cm. NO_3­­­^- leaching was quantified using a soil water budget approach to calculate drainage by examining data from precipitation, evapotranspiration and changes in soil water storage. Data collection and analysis is on-going. Year one data will be presented. We anticipate that EEFs will reduce the amount of NO₃­­­­­­^- leaching compared to a conventional product applied independently of crop demand. This project will help determine methods to more efficiently manage N and protect clean water reserves.