Improved method for field‐scale measurement of ammonia volatilization

Abstract

We developed a new method for determination of atmospheric ammonia (NH₃) emissions from land‐applied nitrogen (N). The new method is a modification of two proven passive flux methods, and is an improvement over these existing methods via reductions in cost, labor and analytical requirements. This new method involves use of one rotating mast placed in the center of a circular plot (15 m radius). The samplers we use are glass tubes (7 mm by 200 mm) that have been coated on the inside with oxalic acid to trap NH₃. This new method was tested against one of the proven methods in a field experiment. A circular plot (15 m radius) was established and urea was applied to supply 200 kg N ha^‐1. Measurements of NH₃ volatilization were then made for six days after application. A strong linear relationship was evident between our new method and the reference method for both horizontal and vertical NH₃ fluxes, as indicated by correlation coefficients of 0.92 and 0.86 for horizontal and vertical fluxes, respectively. The glass tubes that we used consistently absorbed more NH₃ and measured more total NH₃ volatilization than the samplers of the reference method. However, given that micrometeorological methods have underestimated NH₃ volatilization in the past, we feel that our method has improved the accuracy of NH₃ volatilization measurement. In essence, we believe we have developed an improved method for field‐scale determination of NH₃ volatilization by reducing initial costs as well as labor and analytical requirements, without sacrificing accuracy of the volatilization measurement.

Notes

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