Agronomic options for the management of phosphorus in Australian rain-fed organic broadacre farming systems

Summary

The paper is an overview of strategies for agronomic management of P in organic broad-acre farming systems within the Australian rain-fed cereal/livestock belt. It concludes that to raise and maintain adequate plant-available P in these systems the importation of organic manures or composts from off-farm will be required, although the immediate issue may be access to economically viable sources. Improving the P-use efficiency of the system by incorporating species into rotation or intercropping systems that are able to access P from less soluble sources has been a successful strategy elsewhere in the world and deserves further research effort in Australia. Agronomic management to maximise quantity and quality of pasture and crop plant residues undoubtedly builds labile soil organic matter and facilitates P cycling, but the strategy may be of limited benefit in low rainfall areas that do not have the capacity to produce large plant biomass inputs. Progress in selection and breeding for cereal genotypes that are more P-efficient and other plant genotypes that can access less labile P sources is gaining momentum but still remains a long term prospect.