GROWTH OF FORAGES ON ACID SOIL AMENDED WITH FLUE-GAS DESULFURIZATION BY-PRODUCTS

To assess beneficial or detrimental plant growth effects when flue gas desulfurization by-products (FGD-BPs) are applied to acid soil, exper iments were conducted in a greenhouse to determine growth of forages ( orchardgrass, tall fescue, switchgrass, eastern gamagrass, white clove r and alfalfa) on an acid pH 4.6 soil with different levels of three F GD-BPs and chemical-grade calcium carbonate (limestone), calcium sulfa te and calcium sulfite. The FGD-BPs tested were high-CaSO4, high-CaSO4 enriched with Mg, and high-CaSO3. Maximum total plant dry matter (DM) was obtained when similar to 25% of high-CaSO4 FGD-BP or similar to 2 .5% of high-CaSO4 FGD-BP + Mg was incorporated into soil mixes; DM dec reased at higher levels of addition. High-CaSO3 FGD-BP benefited growt h of all species when added at levels up to similar to 3.0% in soil mi xes. Beneficial plant responses were higher for the high-CaSO4 FGD-BPs than for the high-CaSO3 FGD-BP. Maximum beneficial plant responses fo r limestone were at similar to 0.25-0.50% and for CaSO4 at 50-75% in s oil mixes, which were comparable with the high-CaSO4 FGD-BP and high-C aSO4 FGD-BP + Mg responses. Chemical-grade CaSO3 gave no beneficial gr owth effects on any of the plant species. The FGD-BPs used in this stu dy benefited forage growth when added at appropriate levels.