ESTABLISHMENT OF VEGETATION ON BY-PRODUCT GYPSUM MATERIALS

The production of by-product gypsum materials is likely to increase greatly in the future and will require storage in large stacks. Therefore, technology to cover these materials with vegetation will be required. The nutrient requirements for successful plant growth were investigated on three materials [phosphogypsum (PG) from Florida, and two flue gas desulfurization gypsums (FGDG) from Florida and Illinois) using weeping lovegrass (Eragrostic curvula) and lespedeza (Sericia lespedeza) as indicator plants. In the first greenhouse experiment, the requirements for all the essential nutrients were studied in a subtractive design using PG. Significant growth reductions were obtained with the singular elimination of all nutrients except B. Growth on the two FGDG materials was poor due to the presence of high levels of soluble salts. These materials were leached before being studied in the second experiment in which only N, P, and K were varied at constant basal rates of the other essential elements. The 100N-50P-150K (mg kg-1) treatment proved to be the best for total plant growth on all three gypsum materials. The results indicate that providing the proper nutrient balance is important in obtaining good growth on byproduct gypsum materials.