New economic study shows benefits of gypsum
A rigorous new study conducted by two respected agricultural economists brings to light the top reasons that crop growers apply gypsum to cropland. The study cites increased yields, valuable sulfur fertility and soil quality improvements as key benefits of gypsum use, contributing to positive financial returns.
“On average, gypsum users received $1.68 in return for every dollar invested in gypsum. In addition, gypsum significantly improved the productivity of their soil,” said Marvin Batte, Ph.D., professor emeritus of The Ohio State University. “Many gypsum users, especially longer-term users, experienced even higher returns. Plus, there were significant environmental benefits as well.”
Batte and a colleague, D. Lynn Forster, Ph.D., also professor emeritus of The Ohio State University, conducted the study. The research was sponsored by the Gypsoil Division of Beneficial Reuse Management in collaboration with No-Till Farmer magazine.
The study involved an extensive review of published scientific literature, in-depth interviews with several long-time gypsum users and a survey of U.S. farmers. The survey was conducted among readers of No-Till Farmer, as well as farmers that were known purchasers of gypsum.
“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, 2:1 or higher. And there were also excellent returns in other crops, such as soybeans and wheat.”
“Alfalfa is a crop with a high sulfur requirement and gypsum supplies sulfur in the sulfate form, which is readily available to plants, unlike elemental sulfur that must be converted to a usable form,” said Ron Chamberlain, lead agronomist for Gypsoil. The value of sulfur in gypsum is more than $16 per acre for a six-ton alfalfa yield and more than $5 per 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.
Improved soil characteristics
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, according to study authors. Gypsum improves soil tilth and water infiltration, especially in soils with higher levels of clay or silt.
The most valuable soil improvement benefits, rated by a majority of users surveyed, included such items as improved plant rooting, improved seedling emergence, increased soil water retention, reduced runoff and improved absorption of nutrients. Enhanced soil biological activity was also noted.