Flue Gas Desulfurization Residue as a Liming Material for Acidic East Texas Soils.

The State of Texas relies primarily on coal combustion for the generation of electricity, resulting in the production of large amounts of flue gas desulfurization (FGD) residue.  A field plot study was initiated in spring 2007 to evaluate FGD residues as a liming material for the acidic soils of Northeast Texas.  Two rates each of fresh and aged FGD residues were spread on a Leson clay soil (pH = 5.9) in April 2007 and immediately tilled into the upper 6 inches of soil.  Ten days later, soybean was planted into the amended soils.  Soybean leaves collected midway through the growing season showed no significant response in leaf weights or Cd, Cu, Pb, or Zn content due to FGD residues.  Soybean plant height and grain yields, measured in October 2007, showed no response to FGD residues.  In general soybean yields were low compared to traditional yields for Northeast Texas and were probably negatively impacted by excessive rainfall during the early stages of the growing season.  FGD residues significantly increased the level of plant available sulfur and boron in the soil.  Soil pH data exhibited a high degree of variability, but there was an increasing trend in soil pH with the application of FGD residues.  An increase in soil electrical conductivity was also observed as a result of FGD applications, probably due to the presence of sulfate, carbonates and other soluble components in the FGD residue.  Overall results from this study showed that there were no negative environmental impacts due to the addition of FGD to an acidic soil in Northeast Texas, but a follow-up study was initiated in autumn 2007 using FGD rates that were approximately 5 times greater than the previous study.  Results of that study will also be presented.