Applicability of some Methods for Determination of Available Phosphorus in Forest Soils

A comparison of the methods employing five commonly used extractants for the determination of available-P was made on eleven different types of forest soils. Morgan's 10% CH₃COONa in 3% acetic acid buffered at pH 4.8 was most effective in extracting the highest values of available-P in 19 samples out of 22 under study, followed by Dyer's 1% citric acid extractant. Troug's extractant compared well with the Olsen's but both gave very low values. Bray's 0.03 N-NH₄F and 0.025 N HCl extracted lowest values of available-P in the majority of the samples studied. The results indicate that Morgan's method should be used for the routine estimation of available-P in different types of forest soils.