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Rate of Phosphate Reaction with Soil Minerals and Electron Microscope Observations on the Reaction Mechanism
Author(s) -
Kittrick J. A.,
Jackson M. L.
Publication year - 1955
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/sssaj1955.03615995001900030012x
Subject(s) - phosphate , chemistry , kaolinite , fluorapatite , mineralization (soil science) , latosol , soil water , iron oxide , reaction rate , phosphate minerals , reaction mechanism , mineralogy , inorganic chemistry , environmental chemistry , nuclear chemistry , geology , apatite , soil science , catalysis , organic chemistry
The phosphate reaction rate for several soils was found to be very rapid initially, but diminished to lower values in a matter of minutes. For example, the rate of phosphate reaction with a Catalina Latosol after 3 minutes contact was 100 tons of superphosphate per acre per hour but after 1 month the rate of reaction had fallen to about 1 pound per acre per hour. Removal of extractable iron oxides from the Catalina soil greatly diminished the rate of reaction of phosphate with the soil but reaction with the kaolinite portion was nearly half of the total. It was possible to produce colloidal iron oxide and aluminum hydroxide particles analogous to the reactive surfaces responsible for the rapid initial reaction of phosphate with soil minerals. Electron microscope observations of these minerals in contact with phosphate solution disclosed the formation in a few minutes of separate‐phase phosphate crystals by the mechanism of solution‐precipitation. These experiments suggest that the solution‐precipitation mechanism is important in phosphate fixation in soils.