Gypsum Application to Impact Nitrogen Management and to Improve Corn and Forage Yields in Ohio.

Gypsum addition to soil may have several beneficial effects on soil physical and chemical properties and plant growth. These include provision of electrolyte that reduces clay dispersion and improves water infiltration, displacement of excess sodium or aluminum by calcium in sodic or acidic soils, and supply of calcium and sulfur for plant nutrition. In the United States, significant amounts of synthetic gypsum for agricultural use are expected to be available from flue gas desulfurization processes as production increases from the 12.1 million tons in 2006. Gypsum addition at 17% of starting dry weight reduced N loss during composting from 7.3% to 3.6% for dairy manure and from 15.6% to 13.6% for biosolids. Addition of gypsum at 33 kg S/ha increased corn yields at an intermediate N rate of 133 kg/ha and tended to increase corn yields at lower N rates compared to when no gypsum was added. First-year forage yield on a Wooster silt loam with acidic subsoil increased with gypsum application at 20 Mg/ha. Overall, gypsum applications have the potential to impact nitrogen management in various agricultural systems.