PASTURE MANAGEMENT INFLUENCES RUNOFF AND SOIL MOVEMENT IN THE SEMIARID TROPICS

The influence of pasture management (sowing introduced species, timber treatment, clearing and cultivation, stocking rate) on runoff and soil movement was measured on a neutral red duplex soil at Cardigan, near Charters Towers. Runoff and soil movement were greatest in native woodlands and least in developed pastures, although the differences were often not significant. Runoff and soil movement were related to cover levels on the plots. In small rainfall events (total <50 mm and intensity <15 mm/h), runoff and soil movement decreased rapidly as cover increased, and only small cover levels (40%) were needed to reduce them to a low level. As the size of the storm increased, greater cover levels were required, and for very large events (total >100 mm and intensity >45 mm/h) cover had no effect on runoff although it still reduced soil movement. On neutral red duplex soils, managers should maintain at least 40% groundcover but this would still allow large losses of suspended sediment in large storms.