156-23 Wetland Soils Nutrient Index Evaluation.



Monday, October 17, 2011
Henry Gonzalez Convention Center, Hall C, Street Level

Vimala Nair, Mark Clark and Univ of Florida, Soil and Water Science, University Of Florida, Gainesville, FL
To better manage legacy phosphorus (P) in the Lake Okeechobee Watershed, reliable techniques to predict P storage and release from its uplands, ditches, streams and wetlands must be developed. Techniques such as the P saturation ratio (PSR; molar ratio of P to Fe and Al) and the soil P storage capacity (SPSC; a PSR-based calculation of the remaining soil P storage capacity that would consider risks arising from previous loading as well as inherently low P sorption capacity was), originally developed for upland soils are applicable to wetland soils as well. The relationship between water soluble P and SPSC shows that as long as SPSC is positive, WSP is at a minimum, but when SPSC is negative, the release of P from the soil increases. The relationship also holds for SPSC and the equilibrium P concentration (EPC0) determined on the same wetland soils, i.e., when SPSC is positive EPC0 is minimal, but EPC0 increases once SPSC becomes negative. Organic matter in wetland soils does not have any effect on P retention and release when SPSC is positive. The relationship between SPSC and EPCprovides an alternate procedure to assess P release from a soil using parameters in a soil test solution e.g., Mehlich 1-P, Fe and Al, to determine EPC0 without the cumbersome procedure of determining EPCfrom traditional isotherms.
See more from this Division: S10 Wetland Soils
See more from this Session: General Wetland Soils: II (Includes Graduate Student Competition)