Influence of nitrapyrin on N2O losses from soil receiving fall-applied anhydrous ammonia

Fertilizer application in crop production agriculture has been identified as a major source of the greenhouse gas nitrous oxide. Thus, management strategies that increase fertilizer N use efficiency will reduce N2O emission. Anhydrous ammonia applied to cropland in the fall is recognized as a management practice that increases the risk of N loss from the rooting zone, however, this practice is still common in the U.S. Midwest Corn Belt. The nitrification inhibitor, nitrapyrin has been shown to decrease soil N losses during the fall and spring, and maintain fertilizer N availability to the crop. Additionally, nitrification inhibitors have shown promise in reducing soil N2O emissions. However, there have been no studies evaluating the effectiveness of nitrapyrin to reduce annual N2O emissions from land receiving fall-applied anhydrous ammonia. This study was conducted over 2 years to measure N2O emissions from corn plots with fall-applied anhydrous ammonia with and without nitrapyrin. Based on soil NO3 and NH4 analyses, we observed that nitrapyrin delayed nitrification, and in 1 year, reduced late fall/early spring N2O emission. However, annual N2O emissions were not significantly reduced. Significantly higher corn grain yields were observed in the nitrapyrin treatment in both years.