Environmental group: Growth in cover crop use slowing in Iowa

The growth in Iowa farmers’ use of soil-saving and carbon-sweeping cover crops slowed between 2017 and 2019, a national environmental group reports. 

Environmental Working Group’s every-other-year analysis of satellite images showed cover crops such as barley, rye and wheat covered 4.2% of Iowa’s crop acres in the fall and winter. 

Typically, those crops are killed or plowed under in preparation for the next planting season. They have been championed as a way to save soil, soak up chemical runoff and even to sweep small amounts of carbon from the sky.

One in every 20 acres of corn and soybeans in Iowa, Illinois, Indiana and Minnesota were protected by cover crops in 2019, EWG reported, based on its analysis of satellite images.

That amounted to 3.2 million acres out of 68 million in those four states.

In Iowa, cover crops were used on 2.6% of crop acres in 2015, but that grew to 4% in 2017. But the share of acreage 2019 stood at 4.2%, a much smaller gain, the report noted.

That is bad news for the environment, the organization reported. 

“Scientists have known since the Dust Bowl how valuable cover crops are for protecting water, soil and air quality,” report author Soren Rundquist wrote. “Cover crops can also alleviate some of the effects of severe storms associated with the accelerating climate crisis. But farmers just aren’t planting them on enough acres to drive these benefits in any meaningful way.”

The environmental organization has analyzed cover crops in Iowa, Illinois and Indiana since 2015, and added Minnesota for the 2019 study. 

Indiana had the highest use of cover crops with 9.2% of all crop acres. Iowa was second at 4.2%, Illinois had 3.9% and Minnesota, 3.8%.

President Joe Biden and U.S. Agriculture Secretary Tom Vilsack, former governor of Iowa, have said they want to pay farmers to help address climate change. 

But EWG said the science suggests agriculture, while accounting for 10% of greenhouse gas emissions, might not help that much when it comes to reducing heat-trapping carbon in the atmosphere. 

A 2018 study by dozens of researchers at nonprofit organizations, universities and government agencies estimated that planting cover crops on 217 million acres of cropland —14 times the amount of cover crops now planted nationally — would offset 1.6% of U.S. greenhouse gas emissions, EWG reported. 

Of course, the cover crops only help if they are on the ground. And the environmental organization noted that in Iowa, Illinois and Indiana, only 1 in 6 acres were protected both in 2017 and in the 2019 follow-up study. Just 1 in 17 acres were protected in the past three studies. 

Rundquist said cover crops are not planted at a scale that would help much with the “dead zone” in the Gulf of Mexico, a low-oxygen area caused in large part by Midwestern fertilizer applications. He said he hopes the next Farm Bill, which could be considered as early as next year, increases spending for cover crops. 

The Iowa Department of Agriculture and Land Stewardship promotes the use of cover crops, offering cost-share grants.