SIOUX CITY, IOWA, US — A former officer of Farmers Cooperative Society has pleaded guilty for his role in a grain-blending scheme at the Sioux Center, Iowa, US, co-op, the Sioux City Journal reported.

Calvin Diehl entered his plea in US District Court to one count of conspiracy to defraud the United States. He and Kenneth Ehrp are charged with telling workers from 2011-17 to layer soybeans over oats in grain bins and in trucks, and then conceal it from customers and US Department of Agriculture inspectors in order to deceive them about the quality and quantity of grain.

Mixing different kinds of grains is prohibited under federal law unless it is designated as mixed grain or an exemption is granted by federal regulators.

Ehrp faces additional charges of conspiracy, prohibited grain practice and two counts of making false statements. He pleaded not guilty on June 2.

He is accused of causing the co-op’s controller to make a false report to a lender that overstated and overvalued the facility’s inventory in order to influence a loan.