Measuring Dew and Its Effect on Ammonia Volatilization from Surface‐Applied Broiler Litter in the Southeastern United States

Abstract

Core IdeasDew deposition is often overlooked in humid regions but may play an important role in nutrient cycling for surface‐applied fertilizers and broiler litter.Dew accumulated during the measurement period accounted for 6% of the precipitation measured with heaviest dew recorded in the spring and winter months.Under laboratory conditions, simulated dew led to increased ammonia loss for surface‐applied broiler litter.Incorporation of dew as a significant weather variable may better aid in predicting NH3loss using simulation models.Dew deposition is often overlooked in humid regions, such as the southeastern USA, but may play an important role in nutrient cycling for surface‐applied fertilizers and broiler litter. The objectives of this study were to measure dew in a pasture and to evaluate the effect of simulated dew on NH3volatilization in a laboratory study. A microlysimeter method was used to measure dew in a tall fescue (Festuca arundinaceaSchreb.) and bermudagrass (Cynodon dactylonL.) pasture over 206 d. In the 206 d measured, 119 d received dew with an average dew fall of 0.19 mm and greater events observed in the cooler spring and fall months. Dew accumulated during the measurement period accounted for 6% of the precipitation measured. Under lab conditions, the effect of simulated, daily dew (0.2 mm) on NH3volatilization from surface‐applied broiler litter to air‐dry soil was evaluated under diurnal fluctuations of temperature (6–27°C) and relative humidity (26–91%) for 15 d. Dew application significantly increased NH3volatilization losses (31% of the applied NH4–N and 5% of the applied total nitrogen [TN]) when compared with NH3losses in the absence of dew (15% of the applied NH4–N and 2.4% of the applied TN). These results suggest that dew may affect NH3losses from surface‐applied broiler litter under dry field conditions.