A lysimeter study of nutrient losses from urine and dung applications on pasture

Abstract

The effects of superphosphate plus KCl alone, and with dung or urine, on pasture and soil were compared in a lysimeter experiment investigating the fate of applied potassium on a yellow-brown pumice soil. The percentages of K applied in KCl, dung, and urine recovered in herbage and lost in drainage were 73, 80, and 51 and 2, 3, and 4 respectively. Superphosphate plus KCl plus urine showed highly significant increases of exchangeable K down the soil profile compared with superphosphate plus KCl alone. The dung treatment resulted in only minor changes in exchangeable K in the soil. The concentration of magnesium in the herbage was depressed by urine but increased by dung which also increased exchangeable Mg in the soil to a depth of 30 cm. Drainage losses of sulphur from superphosphate, dung, and urine were 41, 0, and 67% respectively, of the amounts of S added. Calcium and Mg losses in drainage were approximately equivalent to nitrate and chloride losses, and it was apparent that the presence of mobile anions, especially chloride, play a major part in the leaching of Ca and Mg from yellow-brown pumice soils.