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Can improved grazing land management reduce sediment yields delivered to the Great Barrier Reef?
This study has shown that following the implementation of grazing BMP pasture biomass and ground cover increased, and hillslope sediment yields declined where scalds were not connected to gullies and streams. Where large low cover patches are located at the base of a hillslope, adjacent to gully or riparian areas, sediment yield did not decline. More intensive rehabilitation will be needed to improve remaining low cover D condition sites associated with lower slope locations closer to gully and stream networks. Although the term BMP is used throughout this document, it may have been more appropriate to use the term improved grazing management. Further improvements are considered necessary on this property, including an increase in cover to ~83% to match recommended pasture biomass yields for this soil type, before best management practice is obtained. This study also demonstrated that there has been a reduction in runoff with increased cover for low rainfall amounts (up to ~200 mm). For higher rainfall amounts runoff is not strongly related to the amount of cover on the hillslope. This study also demonstrated that runoff is less sensitive to land use change (in the short term) compared to sediment yield. Longer data sets are required to determine if and when hydrological recovery will occur in these landscapes. Improved GLM did not result in significant reductions in sediment yield at catchment scale, due to inter-annual variability in rainfall, and dominance of subsoil erosion from gullies and stream banks. Further research is required into the effectiveness of scald and gully erosion treatments which were not considered in the study.
This page was last updated on 24/07/2017
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