Ammonia Volatilization from Liquid Swine Manure Applied to Cropland

Abstract

Randomized complete block design field experiments were conducted to determine the effects of rates and methods of liquid swine manure application on volatile NH₃‐N losses from cropland. In addition, a greenhouse study was conducted to determine the effect of wind on the rate of NH₃‐N volatilization from soil and the accuracy of NH₃‐N loss measurements under field conditions. A partially closed system was utilized to directly collect volatilized NH₃‐N from microplots.The NH₃‐N collection system did not accurately estimate volatile N losses when windy conditions existed as often encountered in the field. Using direct measurement of NH₄⁺‐N in waste before and after exposure to the atmosphere to correct for the low estimates of NH₃‐N loss under field conditions, an average of 48.1% of the volatilized N was collected under greenhouse conditions with relatively constant temperature and wind.The rate of NH₃‐N loss from manure increased with increasing temperature and air movement. The proportions of the applied NH₄⁺‐N lost as NH₃‐N during a 3.5‐day sampling period in the spring from swine manure (pH 6.4) applied to soil (pH 6.4) and corrected for the effect of wind were: 14.0%, 12.2%, and 11.2% for the 90, 135 and 180 metric ton/ha, respectively, of surface applied liquid swine manure; 2.5% for both the 90 and 180 metric ton rates, respectively, of injected liquid swine manure; 14.7% for surface applied urea fertilizer (168 kg N/ha); and 65.8% of the applied NH₄⁺‐N from swine manure surface applied (90 metric tons/ha) on a plastic liner. Fresh swine manure (pH 7.8) surface applied at the rate of 135 metric tons/ha on greenhouse loam soil (pH 7.0) lost 82.5% of the applied NH₄⁺‐N in an 8‐day sampling period.