KANSAS CITY, MISSOURI, U.S. — “Cleaner” air from reduced coal-fired electricity generation has affected wheat yields and baking quality of flour milled from wheat grown on sulfur deficient soils, Mary Guttieri, PhD, said at the Wheat Quality Council’s annual meeting held Feb. 19 in Kansas City.

The amount of sulfur in the air, largely from coal-fired electricity production, which falls to the ground in rain and is naturally “fixed” in soils, before being utilized by wheat plants once was adequate to produce desired sulfur levels in wheat and flour, said Guttieri, who is with the Agricultural Research Service of the U.S. Department of Agriculture based at Kansas State University in Manhattan. But in 2003, the line was “crossed” where more sulfur was being removed through harvest than was being fixed in soil from the atmosphere, she said. Sulfur also is available through crop residue, she said.

Sulfur deficiency looks much like nitrogen deficiency in the field, she said.

“Low sulfur really affected protein quality,” Guttieri said.

Research from Kansas State showed flour deficient in sulfur had lower farinograph results (dough and gluten qualities, especially water absorption) than flour with adequate sulfur.

Guttieri said flour with low sulfur also may test high for asparagine, an amino acid that with certain sugars forms acrylamide in the baking process.

While adding sulfur to fields has shown mixed results, apparently mostly depending on the amount of organic matter and sulfur already in the top two feet of the soil, it appears about 10 pounds per acre of sulfur added in granular form (versus liquid) has the most beneficial results in fields that have less than 20 pounds of available sulfur, she said.