Nitrous Oxide and Ammonia Emmission Reductions with Polymer Coated Urea.

Nitrogen (N) is generally the most limiting nutrient in soil-based ecosystems and is essential for high output crop production and useful in urban environments. Inherent inefficiencies associated with the uptake and cycling of this nutrient result in atmospheric and groundwater pollution. Polymer coated urea (PCU), a newly developed controlled-release N fertilizer, may be a potential solution to this problem. PCU has been shown to meet plant demand in a timely and efficient manner through temperature-controlled N release. The improved efficiency of this fertilizer has been demonstrated in increased crop yields and quality, less labor-intensive fertilization, and reduced nitrate leaching. It is hypothesized that this PCU may also decrease nitrous oxide (N2O) and ammonia (NH3) emissions. The objective of this study was to determine the effect of PCU on the relative nitrous oxide and ammonia loss to the atmosphere using photoacoustic gas analysis. Regular urea and PCU were applied at two rates (67 or 100% of recommended) to differing soil types and moisture regimes in the course of this study. Samples were taken continuously every 30 minutes by an autosampler for the duration of the trial. Results show that PCU significantly decreased emissions of both ammonia and nitrous oxide by 46.1% and 59.6%, respectively, as compared to the regular urea treatments. Ammonia losses peaked at 11 and 30 mg kg-1, and averaged 4.6 and 8.7 mg kg-1 for PCU and urea, respectively. Nitrous oxide losses peaked at 7 and 28 mg kg-1 and averaged 4.6 and 11.4 mg kg-1 for PCU and urea, respectively. These results suggest that PCU significantly increases N-use efficiency. This increase in efficiency enables a reduction in greenhouse gas emissions and nitrate leaching.