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Development of an alternative to the Olsen bicarbonate‐extraction test for determining plant‐available phosphorus in basaltic soils
Author(s) -
Bell A.A.W.,
Bailey J.S.,
Smith R.V.,
Allen M.M.
Publication year - 2005
Publication title -
soil use and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.709
H-Index - 81
eISSN - 1475-2743
pISSN - 0266-0032
DOI - 10.1111/j.1475-2743.2005.tb00406.x
Subject(s) - soil water , ammonium oxalate , basalt , saturation (graph theory) , degree of saturation , phosphorus , soil science , environmental science , soil fertility , sorption , environmental chemistry , chemistry , geology , mathematics , geochemistry , inorganic chemistry , organic chemistry , adsorption , combinatorics
Abstract. Recent work has demonstrated that the Olsen test for phosphorus (P) is an unreliable predictor of plant‐available P in soils derived from basalt parent material in Northern Ireland. The present study was conducted to develop a more reliable soil‐P test for these soils by regressing P fractions removed from soil by various chemical extractants against herbage P indices calculated from plant tissue test data using a diagnosis and recommendation integrated system. The degree of P saturation of the soil P sorption capacity, based on ammonium oxalate extractable P, Al and Fe, provided a better prediction of P available to swards on basaltic soils than either the Olsen test or a number of other well‐known soil‐P test procedures. The superiority of the degree of P saturation test on basaltic soils was attributed to the fact that it simultaneously takes account of both P quantity and P buffering capacity factors in predicting P availability. The Olsen‐P test, which accounts for the P quantity factor alone, was only reliable for non‐basaltic soils. Re‐classifying the P fertility status of basaltic soils according to the degree of P saturation test could result in considerably less P being recommended for these soils with possible consequential benefits to water quality.