Nontraditional Soil Amendments
The primary ingredient in wallboard is gypsum or calcium sulfate (CaSO4•2H2O). In contrast to limestone, which is very insoluble, gypsum is a highly soluble source of calcium (and sulfur). Gypsum has long been used as an agricultural soil amendment to supply calcium and sulfur needed for plant nutrition. It also has been used to promote movement of calcium deeper into the soil and alleviate subsoil aluminum toxicity. Research with ground scrap wallboard has shown it performs as well as commercially produced gypsum. However, research with gypsum and waste wallboard conducted on agronomic crops in the northeastern United States generally has not shown beneficial effects on crop yield. Waste wallboard needs to be crushed or ground before application to agricultural soil and should be free of foreign objects such as nails, screws, and corner bead. Trace element contamination is normally not a problem with scrap wallboard; however, a complete trace element analysis should be obtained.