Phosphorus Sorbing Materials: Sorption Dynamics and Physicochemical Characteristics
- J. W. Leadera,
- E. J. Dunne *b and
- K. R. Reddyb
The effectiveness of various management practices to reduce phosphorus (P) loss from soil to water can potentially be improved by using by-product materials that have the capacity to sorb phosphorus. This study evaluated the P sorption and desorption potential, and the physicochemical characteristics of various phosphorus sorbing materials. Twelve materials were selected and P sorption potentials ranged between 66 and 990 mg kg−1 Iron, and calcium drinking water treatment residuals (DWTRs), a magnesium fertilizer by-product, aluminum, and humate materials all removed substantial amounts of P from solution and desorbed little. Humate had the highest maximum P sorption capacity (Smax). Materials which had a low equilibrium P concentration (EPC0) and a high Smax included aluminum and humate by-products. In a kinetic study, the Fe-DWTR, Ca-DWTR, aluminum, and magnesium by-product materials all removed P (to relatively low levels) from solution within 4 h. Phosphorus fractionation suggests that most materials contained little or no P that was readily available to water. Sand materials contained the greatest P fraction associated with fulvic and humic acids. In general, materials (not Ca-DWTR) and magnesium by-product were composed of sand-sized particles. There were no relationships between particle size distributions and P sorption in materials other than sands. The Ca- and Fe-DWTR, and magnesium by-product also contained plant nutrients and thus, may be desirable as soil amendments after being used to sorb P. Further, using Ca-DWTRs and Fe-DWTRs as soil amendments may also increase soil cation exchange and water holding capacity.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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