Flue Gas Desulfurization (FGD) Gypsum to Reduce, Runoff, Erosion, Sediment and Nutrient Load.

FGD gypsum which is very pure, cheap, dissolves rapidly, and meets all EPA regulations is the ideal anti-erosion soil amendment because it reduces clay dispersion that is the antecedent to erosion. Every soil has a unique relationship between electrolyte concentration (EC) and exchangeable sodium percentage (ESP) even at very low ESP levels (stability diagram) that determines whether clay will disperse when subject to the impact of raindrops or other sources of energy. This clay dispersion sets in motion the cascading sequence of reduced infiltration and increased runoff that leads to soil and nutrient losses. Application of FGD gypsum to the soil surface which allows it to dissolve instantly in impacting raindrops effectively reduces clay dispersion allowing more water to enter the soil thus reducing runoff and subsequent erosion. Where this erosion takes place from disturbed areas such as construction sites FGD gypsum can be used to flocculate clay in retention ponds prior to release of clear water. Because surface-applied FGD gypsum also reduces overland flow of water it is effective in reducing the transfer of N and P to surface waters, particularly from fields on which animal manures have been surface-applied. Polyacrylamide (PAM) when applied together with FGD gypsum has a strong synergistic effect enhancing the benefits of gypsum. In addition, FGD gypsum applied before urea or with animal manures can reduce ammonia volatilization after urea hydrolysis. Examples of each of these uses for FGD gypsum will be presented.