Assessment of a phosphorus fractionation method for soils: problems for further investigation

• Published in: Agriculture, ecosystems & environment Vol. 34; no. 1; pp. 453 - 463
• Main Authors: Potter, R.L., Jordan, C.F., Guedes, R.M., Batmanian, G.J., Han, X.G.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.1991
• Subjects: acid soils; bioavailability; biogeochemical cycles; ecosystems; extraction; fractionation; fumigation; incubation; methodology; phosphorus; sample processing
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/0167-8809(91)90128-K

A sequential extraction method developed by Canadian researchers is described which allows the fractionation of biologically meaningful soil phosphorus (P) pools. The method was originally developed for use on neutral to mildly alkaline soils. Determination of microbial P as part of the fractionation scheme by the flush of NaHCO 3-extractable P following CHCl 3 fumigation is erratic in acid, highly weathered soils. This is explainable based on the large capacities of these soils to sorb P. Sequential extraction of both fumigated and unfumigated samples to determine the fate of P of microbial origin is an alternative. Sample processing can affect results. Incubation of previously air-dried soil reduces bioavailable (resin) P below that present in the air-dried soil. Grinding soil releases some microbial P. Although this is a valuable method, more research is needed on its application to a variety of soils.