USA: A new study highlights the top reasons that crop growers apply gypsum to cropland. The research cites increased yields, valuable sulphur fertility and soil quality improvements as key benefits of gypsum use, contributing to positive financial returns. The study involved an extensive review of published scientific literature, in-depth interviews with several long-time gypsum users and a survey of US farmers.
"On average, gypsum users received US$1.68 in return for every US$1 invested in gypsum. In addition, gypsum significantly improved the productivity of their soil," said Marvin Batte, professor emeritus of The Ohio State University. "Many gypsum users experienced even higher returns. Plus, there were significant environmental benefits as well."
"Returns were highest for alfalfa where users experienced dramatic increases in yield," said Batte. "In alfalfa, returns per dollar of gypsum cost were often 5:1 or higher. In corn, returns were 2:1 or higher. Alfalfa is a crop with a high sulphur requirement and gypsum supplies sulphur in the sulphate form, which is readily available to plants, unlike elemental sulphur that must be converted to a usable form," said Ron Chamberlain, lead agronomist for Gypsoil. The value of sulphur in gypsum is more than US$16/acre (24281m2) for a 6t alfalfa yield and more than US$5/acre for a 200-bushel corn crop. Producers also found that gypsum improved the effectiveness and efficiency of other plant nutrients, including nitrogen, phosphorus and potassium.
While increased yield and improved fertility were among the easiest benefits to measure, improved soil quality was viewed by many, especially long-time gypsum users, as the most important benefit. The most valuable soil improvement benefits included improved plant rooting, improved seedling emergence, increased soil water retention, reduced runoff and improved absorption of nutrients. Enhanced soil biological activity was also noted.
