Comparison of low-cost methods for measuring ammonia volatilization

Nitrogen fertilizer use to improve crop production is increasing worldwide, and subsequent N losses via NH₃ emissions generate undesirable economic and environmental consequences. Th us, low cost and practical methods to quantify NH₃ emissions are essential for the development of management practices that minimize environmental impacts. the objective of this study was to compare different methods to quantify NH₃ loss following urea application to a grass field and indoor soil boxes. the methods tested were: semi-open chamber (SOC), open-collector (OC), closed chamber (CC), and a recirculating chamber (RC). the SOC and OC were shown to be equally efficient. Cumulative recoveries through 216 h for the outdoor study were 9.5 and 8.5 kg NH₃–N ha^–1 for OC and SOC (respectively), corresponding to 8 and 7% of the applied N. the closed-chamber recovered only 3.6% of applied N. For the indoor study, higher recovery rates were observed with all methods. Cumulative losses measured through 216 h did not differ between SOC and OC (24.4 and 24.9 kg NH₃–N, respectively) and represented about 20% of N applied. However RC and CC recovered 10 to 12% of the applied N (14.8 and 12 kg NH₃–N ha^–1, respectively), which was significantly less than amounts recovered with OC and SOC. Results from this study showed that SOCs and OCs are simple, practical, and low cost tools for quantifying NH₃ emissions either for indoor and outdoor studies compared with closed and recirculating chambers which presented disadvantages such as low NH₃ recovery and higher costs.