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Depletion of soil phosphorus as assessed by several indices of phosphorus supplying power
Author(s) -
Yli Halla M.,
Hartikainen H.,
Väätäinen P.
Publication year - 2002
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1046/j.1365-2389.2002.00471.x
Subject(s) - phosphorus , chemistry , bicarbonate , environmental chemistry , langmuir , soil test , soil science , soil water , zoology , environmental science , adsorption , organic chemistry , biology
Summary This study attempts to clarify the advantages and shortcomings of various laboratory tests that are used to characterize the status and dynamics of soil phosphorus (P). We analysed a set of soil samples differing in P status for inorganic P fractions, water‐soluble P (Pw60) and bicarbonate‐extractable P (P Olsen ) both before and after a pot experiment in which soil was depleted. Their P exchange characteristics were determined by Q / I plots, fitted by a modified Langmuir equation, and the supplying power was further assessed by extracting soil samples with various amounts of water. The sensitivity of the P tests in assessing the decrease in inorganic reserves of P was expressed using a response index that was defined as the ratio between the decrease in inorganic P and the decrease in soil P test value. For P Olsen , the index ranged from 6 to 11 and for Pw60 from 10 to 26. Desorption curves obtained by extracting soil samples with different amounts of water indicate increased buffering power and that large reserves of P were released from soil in weak solutions (P < 0.030 mg l −1 ) around soil particles. Although the constants of the Langmuir equation responded reasonably well to the changes in reserves of P in the soil, the results suggest caution is needed in the quantitative interpretation of the constant Q 0 (instantly labile P) of the Langmuir equation.