Ammonia and hydrogen sulphide flux and dry deposition velocity estimates using vertical gradient method at a commercial beef cattle feedlot

Abstract

Ammonia and hydrogen sulphide flux and dry deposition velocity were estimated using micrometeorological vertical gradient flux method at a commercial cattle feedyard of approximately 50,000 head of beef cattle and average 14.4 m²/head (150 ft²/head) stocking density. Ammonia-N and H2S-S loss had general diurnal patterns with the highest fluxes in daytime and lowest fluxes in nighttime that correlated to temperature changes and active evaporation process during daytime. The highest average deposition velocities also occurred during daytime with unstable atmospheric conditions and the lowest during nighttime with very stable conditions. There are exponential relationship between NH3-N flux and ambient temperature with R² = 0.57 for NH3 (NH3-N flux = – 1.46 + 7.96e0.077*Temperature) and R² = 0.22 for H2S-S (H2S-S flux = – 0.75 + 0.8e-0.013*Temperature).