Losses of nitrogen from urine on soils from south western Australia

Abstract

Nitrogen loss from sheep urine was measured on two soil types under different surface cover and moisture conditions at a location with high summer temperatures. Some of the factors influencing nitrogen loss were studied in pots and lysimeters. Grass plants utilized almost half the nitrogen applied in urine. Loss of nitrogen by volatilization and leaching was considerably less under a grass cover than on bare soil. When urine was applied during the hot summer months, there were large losses (50 per cent) of nitrogen even under a grass cover. During the summer, rewetting of urine patches to simulate rainfall increased the amount of nitrogen lost. Eighty per cent of the urine nitrogen was lost after three wettings. Frequency of wetting was more important than volume of water applied. Urine application markedly increased the pH of the soils over a long period.