The Iowa Environmental Protection Commission (EPC) on Tuesday retained the rights of producers to fertilize soybean ground with liquid manure.

According to a report in the Des Moines Register, the nine-member commission preserved a five-year-old rule that allows up to 100 lb. of nitrogen per acre from manure on soybean fields.

In 2006, the EPC discussed concerns regarding nitrogen leaching when manure is applied to soybeans, a nitrogen-fixing crop. And the EPC issued its rule that called for imposing a total ban five years later, unless further scientific research supported alternative action. In 2011, Gov. Terry Branstad installed a commission that was more representative of agriculture.

An earlier study from Iowa State University indicated that the practice would have little effect on nitrate pollution, but add to water treatment costs and contribute to a dead zone in the Gulf of Mexico.

The Iowa Soybean Association, Iowa Pork Producers Association, Iowa Farm Bureau Federation and Iowa Corn Growers Association oppose the ban, arguing that variations in soil conditions and farm management warrant sparing use of manure on fields. Most farmers want to reserve the manure for corn acres to save on commercial fertilizer purchases, and some have started raising hogs mainly for manure production, according to the newspaper’s report.

The meeting of the EPC was repeatedly disrupted by the Iowa Citizens for Community Improvement and adjourned early.