Phosphorus Dynamics and Bioavailability in Andosols : Estimation of Potential Bioavailable P Transport in Agricultural Runoff of Andosols

Abstract

In this study, we estimated the potential bioavailable P transport in agricultural runoff of Andosols from the relations between P sorption saturation and anion exchange resin and Mehlich-3 extractable P, with special references to the difference in active Al composition. the P sorption saturation of 10%, that is optimum P level needed for good crop yields, is critical point of inorganic P for the potential bioavailable P loss in surface runoff from agricultural Andosols with different active Al composition. However, silandic A and B soils showed lower values of Mehlich-3 P than aluandic soils when they had the same P sorption saturation. Mehlich-3 P underestimated the bioavailability of soil P in the silandic soils compared to the aluandic soils. We recommend the use of different critical values of Mehlich-3 P for assessing the upper critical limits for P in aluandic and silandic Andosols