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Gypsum applications on no-till fields could decrease surface crusting while improving aeration and water infiltration, thus aiding crop emergence, according to Warren Dick, an Ohio State University soil scientist.
“Your soils might benefit from gypsum applications if they have a sulfur or calcium deficiency. Gypsum is an excellent nutrient source for calcium and sulfur,” says Dick, who notes that gypsum is actually calcium sulfate.
“If you have surface crusting after a rain or irrigation, or if you have poor percolation, you might benefit from gypsum applications,” he adds, or if subsoil pH measures less than 5.5.
Gypsum qualifies as both a fertilizer, because it provides sulfur as a crop nutrient, and as a soil amendment because it improves soil structure to aid crop growth.
“Gypsum has been used for many years,” Dick says. “We know it reduces Al3 concentrations. If you have acidic soil, many times it’s the Al3 that’s toxic to the plant roots, not the acidity. So when you have low pH, gypsum can move into the subsoil and tie up the aluminum. It won’t change the pH, but it will help overcome some of that toxicity.”
Gypsum also can improve air exchange in and out of the soil, reduce subsurface swelling and decrease surface crusting, thereby helping seedling emergence.
“We’ve actually had the best luck when we apply gypsum with limestone,” Dick says. “We get the benefit of the pH adjustment of limestone, while the calcium sulfate moves into the subsoil, ties up the aluminum…