This study investigates the relationship between pasture production, runoff and soil loss from four small catchments in the mulga lands of south west Queensland over a three year period. The mulga lands of south west Queensland are degrading under current land use practices. In areas that are over - utilized as much as 80% of a storm can be lost as runoff. Losses of this order cause severe erosion and place the area in an artificial drought situation. A positive linear relationship has been found between soil loss and rainfall and a dependent negative cubic relationship between soil loss and vegetation cover. Landholders within the mulga lands could theoretically reduce infiltration losses to 10% of the average annual rainfall compared to the current 40% by doubling the residual vegetation canopy cover after grazing. By doubling the residual vegetation canopy cover soil loss would be reduced to one tenth of that currently experienced. The infiltration losses estimated to be occuring in the mulga lands equates to potential production losses of dry matter of in excess of 400kg /ha. The implications of the relationships derived by this study for management are discussed and the relationship modelled. Losses of preferred plant species through overgrazing were negligible for the three years of the trial.
RUNOFF AND SOIL LOSS FROM FOUR SMALL CATCHMENTS IN THE MULGA LANDS OF SOUTH WEST QUEENSLAND
Australian Rangeland Society
6TH Australian Rangeland Society Conference