Evaluation of Nitrogen Recommendation Strategies to Mitigate Nitrous Oxide Emissions in a Corn Cropping System.

Effective management of N in corn cropping systems can positively impact production, and mitigate environmental impacts such as nitrous oxide (N₂O) emissions. The goal was to quantify N₂O emissions and the response of corn to application of N employing diverse management approaches (“conventional”, “ground- & aerial sensing”, & “modeling”) to identify effective N management strategies. In 2016, a corn (Zea mays) study was established on a Belvue silt loam soil at the Ashland Bottoms Research Farm approximately 8 km south of Manhattan, KS (39º 11’ N lat, 96º 35’ W long). The study was a random complete block design comprised of nine treatments replicated four times. Nitrogen treatments were surface band applied as 28% urea ammonium nitrate and included: check- [0 kg N ha^-1], soil test- [preplant 185 kg N ha^-1; split- 62 kg N ha^-1 at planting and 123 kg N ha^-1 V6-V8], handheld sensor I and II- [56 kg N ha^-1 at planting and 22 kg N ha^-1 V10-V12], aerial NDVI- [56 kg N ha^-1 at planting and 63 kg N ha^-1 V10-V12], satellite NDVI- [56 kg N ha^-1 at planting and 78 kg N ha^-1], model I- [56 kg N ha^-1 at planting, 26 kg N ha^-1 at V10-V12 and 26 kg N ha^-1 at V14], and model II- [56 kg N ha^-1 at planting and 63 kg N ha^-1 V10-V12]. The cumulative seasonal flux for the control treatment was 0.041 kg N ha^-1. No statistical difference was observed among the treatments (alpha=0.5). Site characteristics, coupled with excess precipitation early in the growing season potentially gave way to pronounced leaching, thus lowering the nitrogen available for denitrification. Further investigation is needed to assess the ability of nitrogen recommendation strategies to lower N₂O emissions.