Impact of FGD Gypsum Application On Water Quality in a Coastal Plain Soil.

There are growing concerns regarding the fate of nutrients, especially P, from land application of animal waste.  One approach to reduce runoff losses of P is to treat manure or the soil receiving manure with chemical amendments.  This study used rainfall simulations to examine the impact of FGD gypsum application on runoff nutrient losses on a Coastal Plains soil (Luverne fine, mixed, semiactive, thermic typic hapludults).  Four rates of FGD gypsum (0, 1, 2, and 4 Tons ha-1) were applied to plots of Coastal bermudagrass (Cynodon dactylon (L.) Pers.)
which had received application of 6 Ton ha-1 poultry litter.  Plots with 4 Tons ha-1 but no poultry litter and plots with no litter or FGD gypsum were also utilized.  Rainfall simulator was used to generate water runoff for 60 min runoff and runoff samples were analyzed for dissolved 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 up 61% reduction in SRP concentration in runoff with the application of 4 Ton ha-1 FGD gypsum.   This translated to a 51% reduction in total SRP load during the 60 min runoff event.  Measurement of heavy metals in runoff where all found to be below detection limits.  The results indicate that use of FGD gypsum on pastures receive poultry litter in the Coastal plains would be an effective method of reducing SRP losses to the environment.