The first main aim was to assess the forms of P in a variety of livestock manures collected in eastern Australia. The second main aim was to determine the crop responses to increasing rates of fertiliser P supplied as either CM or MAP under field conditions. The third main aim was to assess the fate of fertiliser P in soil supplied as either CM or MAP. The fourth main aim was to determine the crop recovery of a ‘fresh’ addition of MAP in the year of application to soils that had been previously fertilised with either CM or MAP under field conditions. Lastly, a brief economic assessment was carried out on CM and MAP as a source of P to crops.

This project shows that livestock manure can be used to offset mineral-based fertilisers, and may be the most economic option of P in certain regions. Furthermore, this project shows that the majority of P in livestock manure was that of inorganic P, and behaved in similar manner when added to soil compared to that of MAP. Since there was no significant difference in crop responses to CM and MAP, growers have flexibility on choosing CM or MAP as a source of fertiliser P. Fertiliser decisions can be more easily made on the cost of each fertiliser type based on $/kg P needed to meet a target P rate.