Wetland Soils Phosphorus Criteria Development.

In response to USEPA requests to establish numeric nutrient criteria under the Clean Water Action Plan, methods to evaluate nutrient enrichment in wetland systems has become a major focus for state environmental resource managers. In this effort, soil P indices may prove useful due to their persistence throughout wet and dry periods in a wetland and the capacity of soils to integrate nutrient condition over time.  As developed for upland soils, extractable soil phosphorus in relation to extractable iron and aluminum content can be used to predict thresholds of P release.  Our objective in this study was to evaluate various regulators of P sorption in wetland soils and develop a criterion for P release from wetland soils, bearing in mind that the selected criterion (or criteria) should be practical and the needed parameters easily determined in soil test laboratories. Specific objectives include: i) identifying a routine soil test P or P-related parameter such as the P saturation ratio (PSR) that could be used as an indicator of P release to the water column in wetland soils, irrespective of location or type of wetland, and ii) develop a protocol for determining numeric P criteria and "safe” P levels in wetland soils. Preliminary evaluation has indicated that these objectives can be met: Mukherjee et al. (2009). Development of indices to predict phosphorus release from wetland soils.  Journal of Environmental Quality 38: 878-886.