Summer weeds have an adverse effect on farm viability in southern Australian cropping regions. They use water and nutrients that could otherwise be used by ensuing crops. In the future the importance of summer weeds will increase, since climate change scenarios foresee a greater proportion of annual rainfall occurring during summer. At present our understanding of the economics of summer weeds and their management is inadequate. We need to create the tools necessary for quantifying the costs and benefits of summer weed control, both for the current climate and under changed climatic conditions. This will allow the development of a framework for targeted research and extension aimed at mitigating summer weeds’ impact on production and farm viability.
It was found that summer weeds such as heliotrope, at high density, used 50 millimetres of stored soil water that would otherwise have been available to the following crop.
This research provided valuable information about water use at different densities of summer weeds and enabled the development and validation of a summer weeds module for APSIM, the Agricultural Production Systems sIMulator. The module will be incorporated in Yield Prophet® so that farmers will have easy access to the information.