Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/20/2009
Publication Date: 2/15/2010
Publication URL: www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T3Y-4Y64DCH-1&_user=716796&_coverDate=02%2F15%2F2010&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000040078&_version=1&_urlVersion=0&_userid=716796&md5=45eabd6c67d5affb39e5bd3bdbc60a34
Citation: Parkin, T.B., Hatfield, J.L. 2010. Influence of nitrapyrin on N2O losses from soil receiving fall-applied anhydrous ammonia. Agriculture, Ecosystems and Environment. 136:81-86. Interpretive Summary: Nitrous oxide (N2O) is a greenhouse gas that is 300 times more potent than carbon dioxide. Fertilizer nitrogen use in agricultural cropping systems is known to contribute to production of nitrous oxide from soil. Limiting fertilizer nitrogen application to croplands may not be the best remedy for reducing nitrous oxide emissions to the atmosphere if crop yields are reduced. A better strategy is to improve the efficiency of fertilizer N use by the plant. One way to improve nitrogen use efficiency is by the use of the compound, nitrapyrin. Nitrapyrin inhibits bacteria in the soil that convert ammonium fertilizers to nitrogen forms that are more easily lost. A slower rate of ammonium conversion in soil reduces nitrogen losses from the soil system. A two year study was done to document how the use of nitrapyrin addition to soil with nitrogen fertilizer applied in the fall influences nitrous oxide emissions and corn production. It was found that nitrapyrin delayed ammonium conversion in soil, and in one year, reduced late fall/early spring nitrous oxide emissions. However, total annual nitrous oxide emissions were not significantly reduced. Significantly higher corn grain yields were observed in the nitrapyrin treatment in both years. This information will be useful to scientists engaged in development of agricultural practices to reduce soil N2O emissions.
Technical 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 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 two 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 one 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. Based on the IPCC default emission factor for direct N2O emission from fertilizer application to soil we calculate that small reduction in N2O emissions (0.07 to 0.22 kg N2O-N/ha) would result from the higher corn grain-N uptake in the presence of nitrapyrin.