FGD gypsum and FBC byproducts to overcome subsurface acidity effects on wheat grown in an acid soil

摘要

Coal combustion byproducts (CCB) high in Ca are becoming increasingly available as power plants turn to scrubbing to reduce SO_2 emissions. Agricultural use of such combustion byproducts for improving acid soils has potential for increasing beneficial utilization and reducing costs of disposal. Fluidized bed combustion (FBC) byproducts often contain sufficient unreacted Ca sorbent to be effective in raising soil pH, thus replacing agricultural limestone. Gypsum (CaSO_4.2H_2O) is an important CCB component, which, because of its solubility, is able to leach into soil profiles and reduce detrimental effects of subsurface soil acidity that preclude crop root penetration. Columns of an acid Appalachian soil were used to investigate the effects of byproducts on deep rooting. Treatments incorporated into the surface 15 cm of soil were (g/kg soil): no amendment (Check), dolomitic limestone (Aglime) at 3.98, gypsum flue gas desulfurization byproduct (FGD) at 15.88, a combination of Aglime+FGD at 3.98+15.88, a gypsum FGD with 6percent Mg(OH)_2 (FGD+Mg) at 15.88, and a FBC at 6.45. The columns were leached with 138 cm of water. Effectiveness of the byproducts in improving the soil was measured by growing wheat for 34 days in the 105-cm soil solumns, and also by applying a 4-day bioassay technique to soil removed from each 15-cm layer. All byproducts improved the subsurface rooting environment and shoot growth, except FGD, which induced Mg deficiency in the shoots. The Agricultural Research Service of the USDA is involved in research projects to develop management strategies for profitable and environmentally benign use of CCB in agriculture.