Phosphorus in a clay soil recovering from waterlogging

The project aims to find economically sound phosphorus fertilization practices on clay soils where the content of readily soluble phosphorus has decreased as a result of changes caused by prolonged wetness. The project will investigate 1) how different phosphorus fertilizer rates affect the readily soluble phosphorus concentration of the soil as it recovers from wetness, 2) how large phosphorus balance surpluses are required for the soil test phosphorus to start rising from a low level on clay soils, 3) what kind of yield responses are obtained with different fertilizer phosphorus rates on such soils and 4) what are the costs per yield gain with different fertilization rates.