Get reliable science

Matching livestock numbers with seasonal variation in forage supply is a major challenge for rangeland graziers. This paper describes the use of a spatial pasture growth model (Paddock GRASP) to assist stocking rate decisions at either paddock or property levels. The spatial framework allows the estimation of pasture growth on a paddock by paddock basis, when sub-models are parameterised for specific soil types and vegetation communities within individual properties. Forward projection from current conditions for up to 12 months, based on historical climate data, allows the risk associated with alternative stocking options to be readily appreciated. Output from the model includes estimates of the long term carrying capacity of each paddock and pasture type, estimates of the grazing month stocking rate options available at the 20th, 50th and 80th percentile levels of future pasture growth, and expected ground cover at the end of the planning period if the current stocking rate is maintained, again at the 20th, 50th and 80th percentile levels. Understanding of the likely environmental consequences of the current stocking policy and the prospects for future forage availability should provide useful input to stocking rate decisions in a risk management context.