Use of a mechanistic uptake model for evaluating phosphate fertilizer materials

Abstract

A mechanistic nutrient uptake model that predicts nutrient uptake using values for root growth and morphology, uptake kinetics and nutrient supply to the root by mass flow and diffusion has given close agreement between predicted uptake and observed uptake. The model can be used to evaluate availability of fertilizer materials added to the soil without plant growth experiments. The model also indicates the reason for differences between fertilizers. A study was made to evaluate the P uptake from monocalcium phosphate (MCP), diammonium phosphate (DAP), applied to 13 soils. In a second experiment P uptake from MCP, DAP, rock phosphate and partially acidulated rock phosphate were compared at soil pH's of 5.0 and 5.7. Increasing soil pH reduced P availability from rock phosphate and partially acidulated rock phosphate and MCP but not from DAP. The results indicate the usefulness of the model for evaluating fertilizers.