Factors Affecting Nitrogen Losses as Measured Using Forced-Air Wind Tunnels and Nitrogen Mass Balance

Two experiments using wind tunnels were conducted in conjunction with a N mass balance to evaluate the effect of clinoptilolite zeolite clay on ammonia (NH3) losses. Ammonia losses were measured using the wind tunnels during the last six weeks of each feeding period and compared to losses calculated using a N mass balance. Nitrogen loss, pH, surface DM and N contents, and soil and surface temperatures were assessed as possible contributing factors. There were no differences in NH3 volatilization due to dietary treatments. N loss was influenced by date, % DM, surface N and soil temperature. As measured by the wind tunnels, 26.4 to 29.2% of the total N loss (by mass balance) was lost as volatilized NH3. The wind tunnel is a useful tool for measuring gaseous emissions; however, the short measurement period and small area of measurement may reduce the cumulative accuracy compared to mass balance techniques