Influence of nitrapyrin on N 2O losses from soil receiving fall-applied anhydrous ammonia

Abstract

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 N 2O 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 N 2O emissions. However, there have been no studies evaluating the effectiveness of nitrapyrin to reduce annual N 2O emissions from land receiving fall-applied anhydrous ammonia. This study was conducted over 2 years to measure N 2O emissions from corn plots with fall-applied anhydrous ammonia with and without nitrapyrin. Based on soil NO 3 and NH 4 analyses, we observed that nitrapyrin delayed nitrification, and in 1 year, reduced late fall/early spring N 2O emission. However, annual N 2O emissions were not significantly reduced. Significantly higher corn grain yields were observed in the nitrapyrin treatment in both years.