Working to improve soil health can sometimes make a farmer seem a little bold, said Carolyn King, chief agronomist at ContinuumAg, at the recent 2023 Iowa Farm Bureau Young Farmers Conference.

“The idea of planting into green cover crops is a little intimidating,” King noted. “And your neighbors will think you’re crazy.”

ContinuumAg has done extensive tests on the use of cover crops in eastern Iowa, collecting yield and soil health data to back up its claims.

King said ContinuumAg’s data shows little to no yield loss when using cover crops and corn together and soybeans often see slightly improved yields when planted into cover.

Her recommended formula for cover crops with corn is to plant about 30 to 45 pounds per acre of light wheat or rye in the fall, plus 3 to 4 pounds per acre of clover or hairy vetch legumes. In the spring, plant the corn while the mixture is still growing, and terminate with Roundup within 72 hours. 

King also recommends applying nitrogen as starter fertilizer with corn to kick-start the growing process.

“Not all the stuff I talk about will work on your farm. Each location is different,” King said.

Soybeans are more forgiving of cover crops growing around them, King suggested. 

She said she has seen very good results planting about 60 pounds per acre of cereal rye in the fall. In the spring, she said farmers can plant soybeans into standing rye and wait days, or sometimes weeks, to terminate it, depending on field conditions and what they plan to do with the rye.

Rye can also be used for grazing in the fall or early spring, giving cattle producers additional flexibility in feeding plans.

King also said there’s a possibility, especially in southern Iowa, of relay cropping rye and soybeans as an additional revenue source for farms.

Much of her company’s field tests take place in Washington County. She said in her field tests, letting rye grow until July, harvesting it for seed or feed, then planting a full-season soybean behind it results in small yield losses on the soybean side, which she noted were more than compensated by the sales value of rye seed.

She said relay planted fields averaged 30 bushels per acre for rye and 70 bushels per acre for beans in 2022, which she noted was a drier than average year.

King said the value of cover crops comes down to preserving and improving soil health for the future.

Before jumping into any new practice, she said farmers must know their soil type, climate and labor availability. 

And she said farmers must be flexible and willing to experiment to find the right plan for their fields.

“At the end of the day, our focus is that you have good soil health for the next generation, and generations to come,” King concluded.