Rapid and Slow Phosphate Sorption by Mediterranean Soils: Effect of Iron Oxides1
- J. Torrent2
The rate of phosphate sorption (for different levels of P application) by the clay fractions of 20 soils of Mediterranean Spain ranging widely in mineralogical properties could be described by a modified Freundlich equation. The coefficient giving the P sorbed at unit concentration and unit time (taken as a measure of the rapid sorption) was significantly correlated with the amount of crystalline Fe oxides but not with other properties. The time course of the slow P sorption could not be visualized adequately by the modified Freundlich equation. For that particular purpose a simple Elovich type equation was used. This equation fitted the data well and its coefficient describing slow sorption was also correlated with the crystalline Fe oxide content. Both rapid and long-term P sorption decreased when clays were treated with citrate-bicarbonate-dithionite to dissolve Fe oxides.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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