Surface Application of Flue Gas Desulfurization Gypsum and Infiltration Rates in a Coastal Plain Soil.

The poorly drained cultivated soils on the Lower Eastern Shore of Maryland are often subject to excessive runoff.  Flue Gas Desulfurization (FGD) gypsum, a by-product of a process used by utility companies to prevent SO₂ release into the atmosphere, is expected to be in large supply as increasing numbers of coal-fired power plants comply with current air-quality regulations.   This study is measuring the impact of surface-applied FGD gypsum (0, 5, 10, or 15 Mg ha^-1) on infiltration rates in a heavily manured Coastal Plain soil. Field infiltration is being determined using a constant head double-ring infiltrometer in the spring (pre-planting) and fall (post-harvest) over a two-year period. A laboratory rainfall simulation using the same soil and FGD gypsum application rates is also planned in 2013.  Water extractable phosphorus (WEP) levels at infiltrometer sites are being monitored for possible effects on P sorption in the soil, in response to excessive field rates of plant-available P (385 mg kg^-1) from poultry litter use and potential P-loss via subsurface flow.   Sulfur levels in the field soil are also being monitored in consideration of future fertilization plans for the local corn and soy crops.  Preliminary results show indications of a positive correlation between FGD gypsum application and infiltration rate. Inclusion of surface application of FGD gypsum as a Best Management Practice (BMP) has the potential to address two problems simultaneously: disposal of excess coal-scrubbing by-product and phosphorus contribution to Chesapeake Bay eutrophication.