Red Mud /gypsum (AG) is seen as a useful amendment to increase the P retention of acid sandy soils low in this characteristic such as the Bassendean and grey-phase Karrakatta sands. P fertilisers applied to these soils from intensive horticultural production may leach and pollute associated water systems such as lakes, rivers and estuaries. This project examines the response of cauliflower and potatoes to freshly applied and residual AG.