Coal plant sulfur improves soil and corn production

Southern Illinois Power Cooperative (SIPC) has truly turned lemons into lemonade. Under EPA regulations, SIPC is required to reduce the sulfur dioxide emissions that come from burning Illinois coal for electricity generation. The generation and transmission cooperative decided to go the extra mile and install equipment that would take the unwanted SO2 gas and turn it into gypsum; a product that can be used to boost crop production and reduce water pollution from field runoff. “During a time when coal is being attacked from all sides, it’s important to stress some of the good things being done by our industry,” says Leonard Hopkins, Vice President Environmental and Safety for SIPC.

In addition to drastically reducing the emissions from coal plants, SIPC and other energy producers are making beneficial use of waste byproducts like coal ash and SO2. These byproducts of the coal generation process have for many years been turned into cement and drywall, also known as wallboard or gypsum board. But with a new use, some Illinois farmers are seeing a yield bump plus many soil quality benefits from gypsum applications.

Danny Burnett was fighting standing water and other drainage issues on several fields at Burnett Farms, Inc., a southern Illinois farm he operates with his family. That was before the Burnetts tried gypsum applications about five years ago to loosen soils and improve permeability.

An added bonus was that gypsum also supplied sulfur. For several years, Danny and his family had noticed signs of depleted sulfur levels such as yellowing leaves and sluggish yields. Gypsum is a cost-effective source of sulfur nutrient in a highly available form.

The Burnetts first tested gypsum in an 80-acre cornfield. They created four, 20-acre strips, alternating between treatment strips with two tons per acre of GYPSOIL brand of gypsum (CaSO42H2O) and untreated check strips without gypsum. All other inputs were equal.

Results from the gypsum applications were impressive. Not only did rainwater soak in better in soil where gypsum was applied, they saw a dramatic yield bump as well.

“We had almost a 20-bushel advantage on corn,” Danny Burnett says. “I’m not sure if it was the sulfur or the advantage in soil quality that led to the better yields.”

Between Danny and his father, Rollo, and his brother, Chris, the Burnett family farms about 5,500 acres of ground near Metropolis, Ill. They raise corn, soybeans and wheat on soils that range from lighter silty sand to heavier, clay-ridden gumbos that are slow to drain.

As gypsum was used on more acres across the farm, the Burnetts noticed increased water infiltration and less ponding. There was higher organic matter on soil test results, as well. On test strips for soybean acres, the farm saw a 5-10 bushel yield advantage and they noticed visual differences in wheat acres.

“We can definitely see a difference in the permeability of the soil,” Danny Burnett says. “Gypsum helped us on every acre we put it on, so we no longer do test strips.”

Steve Foss is the Burnetts’ crops specialist at Southern FS Cooperative in Marion, Ill. He says he was impressed with gypsum’s impact on the Burnett’s “tight and tough” soil. “Before gypsum was used, that ground would not raise good corn – the corn would simply shrivel up,” Foss says.

So what is gypsum? The GYPSOIL brand gypsum (gypsoil.com) contains about 20 percent calcium and 16 percent sulfur in sulfate form on a dry matter basis. The GYPSOIL product that the Burnetts purchase is produced at Southern Illinois Power Cooperative (SIPC) in Marion, Ill., and sold through Southern FS. GYPSOIL is also sold in 20 other states.

Colonial crop growers used mined gypsum 300 years ago and observed fields were green and lush where it was applied. But over the years, the cost of mining and shipping gypsum to crop producers caused agricultural use to dwindle over time except for use on high value crops like potatoes, tomatoes and peanuts.

That was until synthetic gypsum became available to farmers like the Burnetts. GYPSOIL brand gypsum is a highly pure form of gypsum produced in the wet scrubbing system used at the utility to improve air quality. The resulting product is virtually free of impurities and it has the same basic chemical composition as mined gypsum. It comes in a powdered form that is spread with a lime or litter spreader.

Soil scientists have observed gypsum can improve the physical properties of certain soils, particularly those with high clay content.

“Gypsum changes the physical properties of soil and improves soil health by altering soil chemistry,” says Ron Chamberlain, GYPSOIL’s lead agronomist and director of research.

“The sulfate portion of gypsum binds with excess magnesium in soil to form soluble magnesium sulfate or Epson salts. When it rains, the salts are flushed out of the soil profile,” Chamberlain says. “By adding soluble calcium, we see more soil aggregates and pore spaces within the soil profile which allows water and air to infiltrate better. As soil structure improves, farmers see less compaction and fewer problems from runoff, ponding and erosion.”

Three years ago Chamberlain and independent agronomist Joe Nester of Byron, Ohio, were tapped by soil scientists at The Ohio State University to assist with a multiyear study to measure impacts of gypsum applications on water quality. The on-going study has shown that gypsum applications decrease concentrations of soluble reactive phosphorus (SRP) in tile water by 30-50 percent. This demonstrates gypsum’s potential as an effective tool to help reduce the amount of phosphorus running off farm fields into sensitive waterways.

Recently the Natural Resources Conservation Service (NRCS) created a national conservation practice standard to give states a guide for creating financial incentive programs for farmers initiating gypsum applications in certain at-risk watersheds.

Danny Burnett says he appreciates that conservation tools such as gypsum applications help improve water infiltration and increase organic matter, which can ultimately help manage runoff and prevent environmental problems. “I think farmers ought to be able to do a good job without the government telling us what to do,” he says, referring to potentially stringent regulations for nutrient management.

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