The U.S. Department of Agriculture (USDA) is expecting strong support from farmers, elevators and exporters as it works to reduce the amount of unwanted material, such as weed seeds, in the U.S. soybean supply, according to Greg Ibach, undersecretary for marketing and regulatory services.

The Chinese, the largest buyer of U.S. soybeans, are demanding increased purity for the billions of dollars worth of soybeans they buy from the U.S. every year. That, Ibach told Agri-Pulse news service, means industry here will have to step up to ensure U.S. exports to China don’t suffer.

China wants the percentage of foreign material in U.S. shipments to be cut in half to a maximum of...