Leonard Hopkins, environmental compliance manager with Southern Illinois Power Cooperative, stands in front of a pile containing several thousand tons of gypsum. Power companies produce the substance as a byproduct of coal scrubbing.
Leonard Hopkins, environmental compliance manager with Southern Illinois Power Cooperative, stands in front of a pile containing several thousand tons of gypsum. Power companies produce the substance as a byproduct of coal scrubbing.
MARION, Ill. — Farmers applying gypsum to their fields are experiencing benefits including some big yield increases, according to a company that distributes it.

Executives from Chicago-based Gypsoil provided growers with some information about gypsum application, including results of research they say demonstrates some big yield boosts.

Ron Chamberlain, founder of and chief agronomist for the company, pointed to benefits achieved by farmers using the product.

“We’ve got thousands of acres we’ve been using gypsum on for a little more than a decade,” he said. “It’s amazing the changes it’s making. It’s making a big impact.”

Agriculture cooperative Southern FS partners with Gypsoil to supply the product to farms in southern Illinois.

Gypsum — calcium sulfate — is the main ingredient in drywall, among other things. It is a natural source of sulfur, a mineral lacking on many farms today.

The reduced presence of sulfur on farms may be linked to the federal Clean Air Act, which led to reduced acid rain generated by power plants. Ironically, power plants now are becoming a major supplier of gypsum, a byproduct of the scrubbing process mandated for cleaner-burning coal.

The substance is created through the removal of sulfur dioxide from the coal. Southern Illinois Power Cooperative in Marion is among utility companies supplying gypsum to be used on farms.

Gypsum accumulates naturally and is retrieved by mining, but such mines are low in number in the country. It also is a byproduct of the manufacture of citric acid. In addition, wallboard manufacturers supply some gypsum.

Chamberlain first became acquainted with the product more than a decade ago.

“I understood it could change soils,” he said. “We saw dramatic changes in soils within the first 12 to 24 months. Those farms continue to improve today, 12 years later.

“We’re getting millions of tons of gypsum produced in this method around the United States. Now we have a readily available source of gypsum for agriculture. It’s coming together really nicely. SIPC is a great supplier. They have a nearby source, so it’s reasonable.”

The utility burns the coal, giving off smoke containing particulate and fine ash, which must be removed. The particles are then attached to all the heavy metals.

When the ash is removed, the heavy metals are removed. The remaining substance is then ground into a fine ash, put in water and sprayed in flue gases. SIPC produces about 100,000 tons of gypsum annually.

In the past, power plants paid to have the mountains of gypsum removed. Now they are suppliers. SIPC also provides a nearby cement manufacturer with gypsum, which when added to cement provides more consistent setting.

“The supply of gypsum is very consistent and will be for years to come,” Chamberlain said. “SIPC is stockpiling for us nearby so when we need product we’ve got product available. There are a lot of power utilities around the United States. We are expecting 40 million tons to be produced annually in the United States, with 30 to 32 million available for agriculture.”

A study by Gypsoil over fields in several counties in Iowa resulted in corn yield increases of as much as 40 bushels per acre.

Other crops also have shown yield benefits from annual applications of gypsum. Yield responses were seen in alfalfa fields when gypsum was applied between cuttings.

“The calcium and sulfate sulfur both are nutrients,” Chamberlain said. “It’s water soluble, very reactive. When we apply it to the fields and we get some rain, it’s going to work right away. They are moving down through the soil profile, coming into contact with crop roots.

“As a nutrient source, we’re finding some quite good responses to yield. We know roots need a lot of calcium to elongate and grow. When we use gypsum, we get water down into that. We’re finding a greater root volume.”

Gypsum is used both to change soil structure and as a nutrient. The former use may require as much as 2 tons per acre. As a plant nutrient it requires about 300 to 500 pounds per acre, depending on the outcome of soil sampling.

Chamberlain said it can be applied at any time and is water soluble, though most farmers apply it in the fall, after harvest.

“It’s not damaging or toxic to plants,” he said. “We can go out there anytime that the spreader truck doesn’t damage the field or the crop just by driving over it.”