Three Annual Flue Gas Desulfurization Gypsum Applications on Macronutrient and Micronutrient Losses in Runoff From Bermudagrass Fertilized With Poultry Litter

Considerable amounts of flue gas desulfurization (FGD) gypsum are being produced as a by-product of generating electricity. As a result, beneficial reuse of this by-product is being sought to reduce landfilling and its associated cost. The use of this by-product as a low-cost soil amendment for suppling Ca and S to crops, improving soil structure, or reducing P loss from agricultural fields may be a viable alternative for easing the burden of disposal. In order to better understand the influence FGD gypsum has on nutrient losses in surface water runoff, rainfall simulations were conducted on an Ultisol (Luverne sandy loam; fine, mixed, semiactive, thermic Typic Hapludults) in a bermudagrass (Cynodon dactylon L.) hayfield typical of the US Coastal Plains region. Treatments consisted of applying 0, 2.2, 4.4, and 8.9 Mg ha(-1) FGD gypsum with 13.4 Mg ha(-1) poultry litter (PL) plus a nonfertilized check (no PL or FGD gypsum) and 8.9 Mg ha(-1) FGD gypsumonly as controls. All treatments were applied each May from 2009 to 2011. In 2011, two simulated rainfall events (similar to 89 mm h(-1)) were created to promote runoff for 60 min, one immediately after treatment application and the other 6 months later (end of growing season). The greatest nutrient losses observed were generally during the initial runoff event immediately following PL application. The addition of FGD gypsum alone generally increased Ca and S losses regardless of when the simulated runoff event occurred. Poultry litter additions increased inorganic N (NO3-N and NH4-N) and total P losses in both runoff events and K in the initial runoff event only. Adding FGD gypsum with PL decreased total P concentration losses while increasing NH4-N, Mg, and Mn, primarily in the initial runoff event. Concentrations of Al and Fe in runoff were generally minimal or below detection limits.