Ohio farmer Les Seiler has applied gypsum to his fields for the past five years. His farm is based in Fulton County, Ohio, 40 miles west of Toledo and near the Michigan border where Seiler says cold and wet spring weather is “guaranteed.” According to Seiler, gypsum is a “tool” that contributes to more efficient movement of air and water through the soil profile and helps speed warming of the planting bed in the spring.

Seiler addressed attendees at the recent Midwest Soil Improvement Symposium: Research and Practical Insights into Using Gypsum. The symposium was held on March 7 in Ada, OH, the day after The Ohio State University’s Conservation Tillage and Technology Conference. It drew 175 certified crop advisers, growers, educators, conservationists, company agronomists and others interested in soil quality.

Co-sponsors for the Midwest Soil Improvement Symposium were the GYPSOIL division of Beneficial Reuse Management, Chicago, Ill.; the Conservation Technology Information Center, West Lafayette, Ind.; and The Ohio State University.

Soil is the world’s most under-appreciated, and yet fundamentally important resource, according to David Montgomery, Ph.D., the symposium’s keynote speaker. “Our species depends on it -- 97 percent of our food comes from soil,” said Montgomery, a professor of earth and space sciences at the University of Washington. He is the author of several books including, “Dirt: The Erosion of Civilizations” which provides a historical review of how poor soil management practices can negatively contribute to the fate of agricultural societies.

Gypsum is a “Swiss Army Knife” for soil improvement

The impact of gypsum on soil structure was highlighted in several presentations featured at the symposium. As a soil amendment, gypsum is a “Swiss army knife” in a farmer’s toolbox, said Darrell Norton, Ph.D., a retired soil scientist from the USDA-Agricultural Research Services’ National Soil Erosion Laboratory at Purdue University.

Synthetic gypsum, or calcium sulfate dihydrate, transforms tight clay soils into porous or “friable” soils that allow water and air to infiltrate efficiently, Norton said. In addition to contributing to soil structural changes, gypsum provides a supply of needed soil nutrients, including sulfur that is depleted in many agricultural soils today.1

Jerry Bigham, Ph.D., a professor emeritus in the School of Environment and Natural Resources, The Ohio State University, explained that the clay soil types common in the Midwest often have high concentrations of magnesium, particularly in soils historically treated with dolomitic or high-magnesium limestone. The high magnesium content contributes to unstable soil structure that isn’t efficient in wet or dry conditions, said Bigham.

Gypsum is rich in soluble calcium which helps soften tight soils, explained Bigham. By adding soluble calcium to high sodium (sodic) or magnesium soils, it improves aggregation to increase porosity and enhance air-water exchange within the soil, Bigham explained.

“The balance of air and water in the pore system, in a large part, will determine how successful we are at harvest time,” said Bigham. “With gypsum, you see a dramatic sustained decrease in water dispersible clay and that is what we are after.”

Gypsum has been shown to reduce runoff and soil loss, as well as soluble reactive phosphorus levels in agricultural fields. In late 2012, gypsum application was added to Ohio’s conservation practice standards issued by the Natural Resources Conservation Service (NRCS). A field study led by The Ohio State University is being launched this spring to further measure the impact of gypsum applications in reducing nutrient losses on cooperator farms in the Maumee River and Grand Lake St. Marys watersheds.

New gypsum available

Gypsum has been used for centuries as a crop input. Colonial crop growers observed fields that were more green and lush when mined gypsum or “land plaster” was applied, according to  Warren Dick, Ph.D., a gypsum researcher and professor at the School of Environment and Natural Resources, The Ohio State University. Dick listed several historical and current examples of research demonstrating gypsum’s positive impact on crop yields.2

Despite favorable crop response, the cost of mining and shipping gypsum to crop growers caused the use of mined gypsum to dwindle over time except for certain specialty crops like peanuts and potatoes.

The March 7 symposium drew attention to a new supply of high quality and lower cost synthetic gypsum called flue gas desulfurization gypsum or FGD gypsum. FGD gypsum is produced as a co-product in wet scrubbing systems used to clean sulfur emissions at certain coal-fired utilities. Gypsum is also produced as a co-product at some food-grade industrial manufacturing facilities. Synthetic gypsum has the same basic chemical composition as mined gypsum.

Approximately 120 power plants nationwide have modern scrubbing systems that produce roughly 25-30 million tons of co-product gypsum each year, according to Robert Spoerri. Spoerri is chief executive officer of Beneficial Reuse Management (BRM), the company that markets GYPSOIL brand gypsum. BRM is permitted to market GYPSOIL in 17 states throughout the Midwest, Mid-South and Southeast regions of the United States.

“Our goal is to create a source or stockpile of gypsum that will be within 100 miles of most of the farmland in the country,” Spoerri said.

Recommended application rates

GYPSOIL agronomist and speaker Ron Chamberlain outlined various recommendations on application rates based on specific uses based on specific use. FGD gypsum contains roughly 20 percent soluble calcium or about 400 pounds per ton and 16 percent sulfate sulfur or about 320 pounds per ton, explained Chamberlain. FGD gypsum is regulated on a state-by-state basis, and rigorously monitored. It is highly pure and virtually free of heavy metals and other contaminants, noted Chamberlain.

Chamberlain outlined various recommended rates of application. For soil amendment purposes, GYPSOIL recommends a half a ton to two tons per acre, depending on the soil’s Cation Exchange Capacity, a measure of soil nutrient-holding capacity. As a nutrient source, rates vary between 300 pounds to a half a ton per acre, depending on the crop. For correcting sodic soils, up to three tons per acre are recommended.

Improved soil structure is especially important during extreme weather conditions such as too little or too much water, said Chamberlain. When gypsum is used to improve soil structure, more rainwater is absorbed into the soils. “Water is sponged down earlier in the heavy rain periods and then (the soil) gives it back to the crop when it needs it,” Chamberlain said.

Results

GYPSOIL has monitored on-farm results for the past twelve years. “By the third or fourth year (of use), we are seeing a yield response to gypsum as a soil amendment,” said Chamberlain. “Where it is used as a nutrient source, the response is much quicker where there is a deficiency.” Earthworm activity and rooting are also improved, he adds, which contribute to how the soil performs in extreme weather.

Ohio crop grower Seiler said his corn yield is 20 bushels higher per acre on fields where gypsum and cover crops are used, including during the drought of 2012. Seiler typically applies gypsum at a rate of one ton/acre after wheat harvest or following corn harvest in the fall. “If you’ve got some of these heavier soils, you can help yourself out,” he commented.

Fellow panelist crop grower Jack Maloney, Brownsburg, IN, has also seen dramatic results on his ground where gypsum has been used with or without cover crops. He started applying gypsum to fields every other year 12 years ago. Maloney, who is a no-tiller and farms 2,600 acres in Hendricks and Boone counties, said his per-acre income has increased since using gypsum to help improve soil structure.

“My yields have been going up each year,” Maloney said. Even during the severe drought conditions of 2012, where average yield was only 70 bushels/acre at his Hendricks County farm, Maloney’s corn yield beat the county average by 40 bushels/acre, he said.

For more information about using gypsum and videos of symposium presentations, visit http://www.gypsoil.com/.

References
1 The Fertility of North American Soils, 2010, Bulletin Summary, International Plant Nutrition Institute, March 2011.
2Chen et al, Flue Gas Desulfurization Products as Sulfur Sources for Corn, Soil Science Society of America Journal, VOL. 72, No. 5, September-October, 2008.
3Chen et al., Flue Gas Desulfurization Products as Sulfur Sources for Alfalfa and Soybean Agronomy Journal, VOL. 97, January–February 2005.