Effects of some environmental factors on ammonia volatilization from simulated livestock urine applied to soil

Summary The proportion of the N that was volatilized as ammonia during 8 days, following the application of simulated livestock urine to soil, increased from 25 to 38% as the temperature of incubation was increased from 4° to 20°C in a system with a continuous flow of air at 70% relative humidity. However, volatilization was reduced if the application was followed by simulated rain; the reduction was greater as the amount of rain increased (up to at least 16 mm) and became less with an increasing length of time (up to 2–3 days) after the application of the urine. The effects of the soil water content before application of the urine, and of the relative humidity of the air, were generally small but volatilization was reduced by a combination of air-dry soil with a low relative humidity. Volatilization was slight (7%) when the flow of air was restricted to 0.5 h in every 12 h but, with an air flow for 12 h in every 24 h, the volatilization was much closer to that with a continuous flow for the whole 8-day period. When cool or dry conditions were imposed for 8 days and then more favourable conditions were instituted for a second period of 8 days, there was a substantial increase in volatilization following the change.