Annual ryegrass cover crops improve soil, boost crop yields, researchers say

Natural Resources Conservation Service soil scientist Steve Blanford, in a soil pit at the University of Kentucky Research and Education Center in Princeton, Ky., shows participants in the first ever UK Fragipan Field Day Oct. 3 an example of fragipan, which is a cement-like layer of soil that is reducing yields on 50 million acres in the U.S. The field day showcased how annual ryegrass breaks up fragipan.

Annual ryegrass was king in Princeton, Ky., Oct. 3, as retired University of Kentucky Extension Soil Specialist Lloyd Murdock showcased a relatively unknown benefit the grass species offers farmers in the first ever UK Fragipan Field Day.

“This is our kickoff,” Murdock said. “This is saying to the world, ‘Yes, we really believe it is true.’”

Murdock was referring to research showing that use of annual ryegrass in cover crop and forage systems breaks up fragipan, a cement-like layer that has formed a couple of feet beneath the soil surface on 50 million acres of farmland in the Midwest and Southeast U.S. The layer inhibits yields, particularly in drought years, by blocking corn and soybean roots from reaching water and nutrients below it.

Murdock is leading a multi-pronged research project that is now six years old into the effect of annual ryegrass on fragipan.

“Basically, there is a group of us who banded together to see if we could solve the mystery of the fragipan,” Murdock said.

The first step, he said, was analyzing the chemistry of the cement that bonds fragipan, with hopes of discovering how to dissolve it. The researchers found five elements that break up fragipan, but annual ryegrass, with its vigorous root growth and root exudates, or chemicals it releases that help dissolve fragipan, rose to the top.

“It takes several years, but you can go from a soil that is 20 inches deep to a soil that is 30 inches deep, and you can improve your yields,” Murdock said.

“We are really excited about the fact that this can help 3 million acres in Kentucky and 50 million acres in the United States, and change these soils,” he said.

The half-day field day at the University of Kentucky Research and Education Center in Princeton, Kent., included reports from soil scientists, cover crop experts, a chemist, an ag economist, a forage crop expert and a Southern Illinois farmer who has increased corn yields by 40 percent over the past 20 years by utilizing annual ryegrass as a cover crop on fragipan soils.

Ralph Upton Jr., of Springerton, Ill., said he began using annual ryegrass in the late 1990s as a cover crop in an effort to reduce soil erosion and improve soil health. “I felt like you could kind of see that no-till and cover cropping was the only thing that would revitalize that soil,” he said.

Murdock said he would be surprised if growers in Kentucky can match the kind of success Upton has achieved. “But,” he said, “there is no question from our (laboratory and in-field) research that you do get a yield increase.”

Bryan Ostlund, administrator of the Oregon Ryegrass Growers Seed Commission, which helped sponsor the event, said the field day “was probably the most fact-filled, exciting, half-day field event I’ve ever seen. It is great to be a part of this, to be helping put this on.”

Nearly all of the nation’s annual ryegrass seed is grown in Oregon.

In addition to the economic benefits available to growers, Ostlund said the fragipan project offers huge environmental benefits through preservation of topsoil and a reduction of soil and nutrient runoff into surface waters.

Ostlund, who has been working for more than 20 years with Oregon ryegrass seed growers to increase use of annual ryegrass in Midwest cover cropping systems, said the findings presented Oct. 3 could provide a significant boost.

“Something like this coming along to build on what we already have in other production areas is a great new stepping stone to bigger and better things,” he said.

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