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Forms of Phosphorus and Fixation in Soils
Author(s) -
Cho Chai Moo,
Caldwell A. C.
Publication year - 1959
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1959.03615995002300060027x
Subject(s) - soil water , chemistry , phosphate , fractionation , solubility , phosphorus , environmental chemistry , soil ph , calcium , organic matter , extraction (chemistry) , dissolution , citric acid , inorganic chemistry , soil science , geology , chromatography , organic chemistry
A determination of the main forms of P, P fixation, and a comparison of several methods of determining available P were made on several Minnesota soils. Inorganic and organic forms of P were characterized and the inorganic fraction was further subdivided into aluminum phosphate, iron phosphate and calcium phosphate. Fractionation data of the inorganic P showed that iron and aluminum phosphates were abundant in acid soils while calcium phosphate was abundant in alkaline soils. In soils having a pH near 7, all three forms of inorganic phosphorus were about equally distributed, though slightly more iron and aluminum than calcium phosphate was present. Organic P agreed, in general, with the content of soil organic matter, but some deviation was noted. The capacity of the soils to “fix” P from added KH 2 PO 4 was observed. It was found that the P‐fixing capacity of soils increased with departure from a pH near neutrality. Bray No. 1 and 2, NaHCO 3 , citric acid, Morgan's, and water‐solubility methods of determining available P were compared. Available P in the soils varied greatly depending upon the extraction procedure used. Generally the amounts of available P as determined by methods employing strong acids were higher than those using weak acids. Correlation analysis was carried out on forms of P and the amount of P as determined by the various quick methods.