Changing Stocking Rates and Burning Management to Reduce Greenhouse Gas Emissions from Southern Queensland Grasslands

GRASSMAN, an agricultural decision-support model, has been modified to include sources, sinks and storages of greenhouse gases. The modified model was used to investigate the effects of changes in stocking rate and burning management on greenhouse gas emissions of southern Queensland grasslands. These grasslands are significant net emitters of greenhouse gases in their natural state, resulting in large differences between net and anthropogenic (man-made) emissions and hence, to different conclusions regarding emission reduction strategies. At moderate stocking rates, anthropogenic emissions could be reduced by about 20% with little loss of productivity. However, similar reductions in net emissions require larger management changes with substantial reductions in productivity. At heavy stocking rates, reducing stock numbers reduced emissions while increasing cattle production. Thus productivity per unit of greenhouse gases can be optimised, Reducing burning frequency can reduce greenhouse gas emissions, However, recommendations to minimise burning have to recognise the benefits achieved through burning.