The use of cover crops is gaining popularity across the nation and the Upper Midwest, too, but some farmers still wonder whether the practice makes economic sense.

A new report from the U.S. Department of Agriculture's Sustainable Agriculture and Research Education, or SARE, examines when using cover crops in corn and soybean rotations is prudent financially.

It's important to "look at cover crops as an investment rather than a cost," Justin Zahradka, a Lawton, N.D., farmer, said in SARE material. Zahradka is a cover crops expert and has presented on the topic at a national conference.

Cover crops grown to suppress weeds, control pests and disease and build productive soil, rather than for sale.

The report - based on national cover surveys - found that in 2015 and 2016:

• After one year of cover crop use, corn yields increased 0.5 percent and soybean yields 2.1 percent.

• After three years of cover crops, corn yields increased 1.8 percent and soybeans yields 3.5 percent.

• After five years of cover crops, corn yields increased 3 percent and soybean yields 5 percent.

The report noted that other, smaller studies have shown a variety of increases, including no yield increase. Good planning is needed to get the most favorable results, the report said.

What's true for some farms isn't always true for others, the report noted. But it found these seven situations that can provide a relatively quick positive economic return.

• Herbicide-resistant weeds are a problem.

• Cover crops are grazed. They can be profitable in the first year of use if fencing and water already are available.

• Soil compaction is an issue.

• Cover crops are used to speed up and ease the transition to no-till.

• Soil moisture is at a deficit or irrigation is needed.

• Fertilizer costs are high or manure nutrients need to be sequestered.

• Incentive payments are received for using cover crops.

Nationwide, cover crop acreage rose 50 percent from 2012 to 2017, according to the U.S. Census of Agriculture, the most comprehensive source of information available.

North Dakota alone had 404,000 acres of cover crops, excluding cover crops used in the Conservation Reserve Program, in 2017.

Cover crops hold even more potential promise this summer in soggy areas of the Upper Midwest. They can be used on flooded fields that couldn't be planted in order to hold down weeds and improve the soil, according to SARE.

The organization describes itself as a grant and education program that advances ag innovation to promote profitability, good stewardship and quality of life for farmers, ranchers and their communities.

To order or download a free copy of the report: