Use of clean coal technology by-products as agricultural liming techniques

摘要

Dry flue gas desulfurization (FGD) by-products are mixtures of coal fly-ash, anhydrite (CaCO(sub 4)), and unspent lime- or limestone-based sorbent. Dry FGD by-products frequently have neutralizing values greater than 50% CaCO(sub 3) equivalency and thus have potential for neutralizing acidic soils. Owing to the presence of soluble salts and various trace elements, however, soil application of dry FGD by-products may have adverse effects on plant growth and soil quality. The use of a dry FGD by-product as a limestone substitute was investigated in a field study on three acidic agricultural soils (pH 4.6, 4.8, and 5.8) in eastern Ohio. The by-product (60% CaCO(sub 3) equivalency) was applied in September, 1992, at rates of 0, 0.5, 1.0, and 2.0 times the lime requirement of the soils, and alfalfa (Medicago sativa L.) and corn (Zea mays L.) were planted. Soils were sampled immediately after FGD application and three more times every six months thereafter. Samples were analyzed for pH and water soluble concentrations of 28 elements. Soil pH was increased by all FGD rates in the zone of incorporation (0--10 cm), with the highest rates giving a pH slightly above 7. Within one year pH increases could be detected at depths up to 30 cm. Calcium, Mg, and S increased, and Al, Mn, and Fe decreased with increasing dry FGD application rates. No trace element concentrations were changed by dry FGD application except B which was increased in the zone of incorporation. Dry FGD increased alfalfa yield on all three soils, and had no effect on corn yield. No detrimental effects on soil quality were observed.