|Franklin, Dorcas - University Of Georgia|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2013
Publication Date: 3/1/2013
Citation: Endale, D.M., Schomberg, H.H., Fisher, D.S., Franklin, D.H., Jenkins, M. 2013. Flue gas desulfurization gypsum: Implication for runoff and nutrient losses associated with broiler litter use on pastures on Ultisols. Journal of Environmental Quality. doi: 10.2134/jeq2012.0259.
Interpretive Summary: The mineral gypsum mined from natural deposits or produced in power plants during the process of cleaning the exhaust fumes of sulfur dioxide gas to maintain air quality standards (referred to as flue gas desulfurization gypsum - FGDG) can be a useful soil amendment to overcome some soil, weather and management limitations to agricultural productivity and environmental quality in southeastern United States. Scientists at the USDA-ARS in Watkinsville, GA, conducted a 3-yr study to test this possibility in a hay field. The soil was Cecil which is common in much of the Southern Piedmont. Each year they applied two rates of broiler litter (BL) (0 or 6 tons/ac) along with 4 rates of FGDG (0, 1, 2 and 4 tons/ac) on 18 plots making 6 set of treatments repeated three times (0-0, 0-6, 1-6, 2-6, 4-6, 4-0; X 3). In the 1st and 3rd year they compared runoff and nitrogen, phosphorus, calcium and magnesium loses in runoff from an artificially generated rainfall following soil amendment with BL and FGDG. Runoff as percent of the rainfall for FGDG at the maximum rate with BL was approximately 30% below the 0-0 control each year but this was not statistically significant. Several factors might have contributed to this: variability among and between replications, inherent high infiltration of the hay field, and dry weather contributing to low runoff risk. Amending the soil with broiler litter increased nitrogen and phosphorus levels in runoff several fold compared with the no amendment (0-0). Adding FGDG to the BL-treated soil then reduced nitrate loads in runoff up to 80% but only in the 3rd year. Similarly soluble phosphorus decreased up to 78% due to FGDG but only in the 1stt year. Lesser level reductions for both in the alternate years were not significant. Addition of FGDG increased both calcium and magnesium levels in runoff. These results will serve as useful gauges for those interested in developing FGDG-related best management practices to ameliorate water quality concerns in agriculture. Less than 2% of the approximately 18 million tons of FGDG produced annually in the United States is used for improving agricultural productivity and sustainability.
Technical Abstract: In two controlled rainfall simulation experiments (June 2009 & May 2011), runoff, nutrient (N, P, Ca, Mg) losses, and total suspended solids in runoff were compared among six treatments consisting of four rates of flue gas desulfurization gypsum (FGDG) (0, 2.2, 4.5, 9.0 Mg ha-1) with 13.5 Mg ha-1 each of broiler litter (BL) and two control (0-0) and (9.0-0.0) Mg ha-1 (FGDG-BL) treatments. A randomized block design with three replications was setup on a Costal bermudagrass (Cynodon dactylon L.) hay field on Cecil (Typic kanhapludult) soil near Watkinsville, GA. After three amendments in two years runoff showed a significant quadratic response to increased FGDG rate; however treatment variance limited detecting significant runoff differences despite a ~30% reduction each year in percent runoff from the (9.0-13.5) compared with the (0-0). Increasing FGDG rates reduced concentration and load linearly for nitrate-nitrogen in 2011 and ammonium-nitrogen in 2009. While not significant there were reductions for both in the alternate years. Addition of BL increased soluble P concentration and load several fold compared to (0-0); however, soluble P levels from addition of BL declined with increasing rates of FGDG in 2009. The (9.0-13.5) treatment reduced N and P levels up to 80% compared to (0.0-13.5). The same level of effect was not observed in 2011. Concentration and load of Ca and Mg increased linearly due to increasing FGDG rates. Over 90% of applied nutrients moved into/or through the soil. Addition of FGDG with BL could provide water quality benefits on Southeastern landscapes.