Sustainable Grazing for a Healthy Burdekin Catchment

Summary

This project implemented grazing land best management practices (full wet season spelling and forage budgeting) on Virginia Park Station in the Burdekin catchment in order to examine the impact of these practices on land condition recovery, landscape health and the consequent leakiness of water, sediment, and nutrients both from the hillslope and the catchment. We found that despite a sustained drought during the period of the study, the management practices implemented led to a shift in land condition from C to B through both improved pasture composition and cover levels in the monitored paddocks. Despite these improvements in landscape health, the duration of the study was too short and inter-annual variability too large to link these improved conditions to a reduction in the export of sediment and nutrients, either at the hillslope or catchment scale. However, representing these improvements in landscape condition in a hillslope model has shown that the improvements seen in this study should lead to significant reductions in the loss of sediment and nutrients from hillslopes. Reductions in sediment and nutrient export at the catchment scale are more difficult to quantify as this study suggests that residence times in the stream may be significantly longer than previously thought, and the state-of-the-art in catchment scale modelling (SedNet) is not able to represent these lag times. Research is currently underway in the CSIRO Water for a Healthy Country program to improve catchment-scale modelling and determine residence times of sediment.