Wetland Soils Nutrient Index Evaluation.

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 EPC₀  provides 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 EPC₀  from traditional isotherms.