Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/13/2016
Publication Date: 7/7/2016
Citation: King, K.W., Williams, M.R., Dick, W.A., LaBarge, G.A. 2016. Decreasing phosphorus loss in tile-drained landscapes using flue gas desulfurization gypsum. Journal of Environmental Quality. 45(5):1722-1730. doi:10.2134/jeq2016.04.0132.

Interpretive Summary: Losses of phosphorus fertilizer from agricultural crop production have been linked to harmful and nuisance algal blooms (HNABs) plaguing Lake Erie and other inland waters. Best management practices to reduce phosphorus losses are needed to address these HNAB issues. Flue gas dusulfurization (FGD) gypsum, a by-product of coal-fired electric power plants, was tested as a soil amendment to bind phosphorus. Application of FGD gypsum significantly reduced phosphorus concentrations and loadings in both surface and subsurface discharge. Use of FGD gypsum as a soil amendment proved to be a viable best management practice for reducing surface and subsurface phosphorus loss and ultimately reducing the extent of HNABs.

Technical Abstract: Elevated phosphorus (P) loading from agricultural non-point source pollution continues to impair inland waterbodies throughout the world. The application of flue gas desulfurization (FGD) gypsum to agricultural fields has been suggested to decrease P loading because of its high calcium content and P sorbing potential. A paired field experiment was used to examine the effects of successive FGD gypsum applications (2.24 Mg/ha; 1 ton/acre each) on discharge, dissolved reactive P (DRP), and total P (TP) concentrations and loadings in surface runoff and tile discharge from agricultural fields in Ohio, USA with high soil test P levels (>480 ppm Mehlich-3 P). Results showed that following the first application of FGD gypsum event mean DRP and TP concentrations in tile water and DRP concentrations in surface runoff were significantly reduced; however, no significant reductions were noted in DRP or TP loading. Following the second application, both concentrations and loadings were significantly reduced in the surface, tile, and combined (surface + tile) discharge. These findings indicate that surface application of FGD gypsum can be used as a tool to address elevated P concentrations in drainage waters; however, the effects on loadings, while significant, were not as great. To further assess the use of FGD gypsum as a best management practice, research is needed to determine 1) the effectiveness of FGD gypsum applications to soils with different soil test P levels as well as the effect on crop stress and productivity; and 2) how long after application the effect of FGD gypsum persists.