Author
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Stout, William |
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Sharpley, Andrew |
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Submitted to: Nutrient Cycling in Agroecosystems
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/26/2002 Publication Date: 9/20/2003 Citation: Stout, W.L., Sharpley, A.N. 2003. Effect of biologic extraction on soil inorganic phosphorus (p) stability. Nutrient Cycling In Agroecosystems. 67(1):21-29. Interpretive Summary: In the northeastern U.S., high rates of fertilizer and manure application have resulted in the majority of agricultural soils having excessive amounts of plant available phosphorous. Soils with excessive phosphorus are an environmental rather than agronomic concern, as water-soluble phosphorus runoff from these soils can contribute to increased amounts of phosphorus in surface water, which can contribute to eutrophication in freshwater. Flue gas desulfurization (FGD) gypsum, a coal combustion by- product, can be used to reduce water-soluble soil phosphorus, thereby reducing the potential for phosphorus export to surface waters. This reduction results from the conversion of readily biologically available phosphorus to less soluble forms of phosphorus. The short-term effect of this conversion on plant available phosphorus is small, but the effect on plant available phosphorus over several cycles of plant extraction is not known. In a greenhouse experiment, we measured plant phosphorus extractio from three widely different soils treated with FGD gypsum and determined the extent to which soil phosphorus was being extracted from the various soil phosphorus pools. During the first growth cycle, the shift caused by the FBC gypsum of soil phosphorus from readily available to less available pools treatment tended to remain stable. Sequential biologic extraction continued to reduce the most biologic available pools and thus have a continue effect on reducing water soluble phosphorus. These would indicate that treatment with FBC gypsum would reduce water-soluble phosphorus, and consequently reduce the potential for phosphorus export in surface runoff for several years. Technical Abstract: Flue gas desulfurization (FGD) gypsum, a coal combustion by-product, can be used to reduce water-soluble soil P, thereby reducing the potential for P export to surface waters. This reduction results from the conversion of readily biologically available inorganic P (IP) to less soluble Al- and Fe- bound IP and, to a lesser extent, calcium-bound IP pools. The short-term effect of this conversion on plant available IP is small, but the effect o plant available P over several cycles of biological extraction is not known. In a greenhouse experiment, we measured plant P extraction from three widely different soils treated with FGD gypsum and determined the extent to which IP was being extracted from the various soil IP pools. During the first growth cycle, the shift caused by the FGD treatment of IP from the resin IP pool to the less available pools tended to remain stable. Sequential biologic extraction continued to reduce the most biologic available pools, and thus have a continued effect on reducing water-solubl P. These would indicate that treatment with FGD gypsum would reduce water- soluble P, and consequently reduce the potential for P export in surface runoff for several years. |
