Impact of flue gas desulfurization gypsum application on water quality in a coastal plain soil

There are growing concerns regarding the fate of nutrients, especially phosphorus (P), from land application of animal waste. One approach being studied to reduce runoff losses of P is to treat manure or the soil receiving manure with chemical amendments such as gypsum. This study used rainfall simulations to examine the impact of flue gas desulfurization (FGD) gypsum application on runoff nutrient losses on a Coastal Plains soil (Luverne sandy loam; fine, mixed, semiactive, thermic Typic Hapludults). Four rates of FGD gypsum (0, 2.2, 4.4, and 8.9 Mg ha) were applied to plots of Coastal Bermudagrass ( L.) that had received application of 13.4 Mg ha poultry litter. Plots with 8.9 Mg ha FGD gypsum but no poultry litter and plots with neither poultry litter nor FGD gypsum were also used. Rainfall simulation was used to generate water runoff for 60 min, and samples were analyzed for soluble reactive P (SRP) and soluble Al, B, Ca, Cu, Fe, K, Mg, Mn, Na, and Zn. Total concentration of Ca, Mg, K, Na, Fe, Mn, and Zn and concentration of heavy metals Ar, Hg, Al, Sb, Ba, Be, Cd, Cr, Co, Cu, Pb, Ni, Si, V, Se, Tl, and hexavalent chromium were also analyzed. Results indicated a maximum of 61% reduction in SRP concentration in runoff with the application of 8.9 Mg ha FGD gypsum. This translated to a 51% reduction in total SRP load during the 60-min runoff event. Concentrations of heavy metals in runoff were all found to be below detection limits. The results indicated that use of 4.4 Mg ha FGD gypsum on Coastal Plains pastures receiving poultry litter could be an effective method of reducing SRP losses to the environment.