Ammonia Volatilization from Broiler Litter: Effect of Soil Water Content and Humidity

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Broiler litter is commonly applied to grasslands as fertilizer where it undergoes N losses through NH3 volatilization. Ammonia losses represent not only a loss of plant-available N but also a source of environmental contamination. Previous research has shown that NH3 volatilization from broiler litter is affected by environmental conditions, but the effects of atmospheric water and soil water content (WC) are not well understood. We conducted a study at constant 94% relative humidity (RH) to evaluate rewetting of broiler litter and another study at 32% RH to evaluate drying of broiler litter. We also conducted two laboratory studies to evaluate the effect of soil WC (0.03 vs. 0.13 g H2O g−1) at either 32 or 92% RH on NH3 volatilization from surface-applied broiler litter. Results of the drying and rewetting studies showed that broiler litter can absorb or lose water at a relatively fast rate depending on RH. Ammonia volatilization was greater from wet soil (0.13 g g−1 soil WC) than from drier soil (0.03 g g−1 soil WC) under the high RH (92%), with losses of 21 and 11% of total N, respectively. In contrast, NH3 loss was only slightly greater in wet (0.13 g g−1 soil WC) vs. dry (0.03 g g−1 soil WC) soil at 32% RH, with losses of 5.2 and 3.2% of total N, respectively. These findings indicate that both soil WC and RH may play an important role in NH3 volatilization. Further research should evaluate the effect of diurnal RH changes on NH3 loss from surface-applied broiler litter.