VOLATILIZATION OF AMMONIA FROM CATTLE URINE APPLIED TO GRASSLAND

The volatilization of ammonia from cattle urine applied to grass swards was assessed over several 15 day periods using a system of wind tunnels. The proportion of the urinary N that was volatilized ranged from 3.7 to 26.9%. In 8 of the 9 experiments, at least 70% of the total volatilization occurred within 4 days of application. With 7 experiments carried out at the same site during the months late March to October, there was a positive correlation between soil temperature at 3 cm depth during the 3 days following application and the extent of volatilization assessed over 15 days (r = 0.93). With an experiment carried out in January, ammonia volatilized more slowly (only 56% of the 15 day total occurred within 4 days) but total volatilization was considerably greater than predicted by the correlation with soil temperature noted above. © 1990.