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ISU researchers find corn yields with perennial cover crop equal to traditional farming; recommend Kentucky bluegrass

Soil quality, water quality, and possibly even farm profits will all benefit by using a perennial cover crop on corn fields that allows for similar yields to traditional farming methods, according to Iowa State University research.

Corn remains vigorous with little competition from Kentucky bluegrass. Click to enlarge.

Using standard agronomic practices and managing a perennial cover crop between rows of corn can keep soil, nutrients and carbon in the fields, a three-year study says. Plus, farmers will still be able to yield 200 bushels per acre, the study showed. (Average yield in the US in 2010 was 152.8 bu/acre, according to the USDA.)

For the study, researchers looked at 36 potential ground cover species, different corn hybrids and various tillage practices and found that strip till planting using Kentucky bluegrass as the perennial cover crop is the combination the researchers will recommend to offer environmental benefits while maintaining yield.

We evaluated all these ground covers and decided to work with Kentucky bluegrass, because it's as good as anything else. And Kentucky bluegrass is out in every lawn in Iowa. Every farmer grows it already. Every farmer knows how to kill it. We think farmers will be more likely to accept it as a ground cover.

—Ken Moore, professor in ISU’s Department of Agronomy

Using ground cover to sustain and improve soil has become a focus of research because the need for biomass is increasing for use in producing biofuels. Corn residue, or stover, usually remains on the ground after corn is harvested and helps reduce soil erosion and replenishes nutrients and organic matter. The prospect of removing that stover to make biofuels causes many agronomists to fear that soil erosion will increase, while the remaining soil will suffer nutrient loss, says Moore.

Researchers received a Sun Grant for bio-based research to identify ground covers that are compatible with corn, find corn that is competitive with the ground cover, and develop management systems that minimize competition between the corn and the ground cover. The Sun Grant Initiative is a national network of land-grant universities and federally funded laboratories working together to further establish a biobased economy.

Moore is pleased the results were so encouraging, but additional work is required before he and others recommend farmers try it.

Yes, we can do it [using perennial cover crops]. We don’t know all the potential pitfalls of doing it. Under the circumstances that we tested, it does work.

—Ken Moore

The bottom line is that with our best treatment, all three years we found yields in the control and yields in the Kentucky bluegrass with herbicide suppression and fall strip till were not different, which is very exciting.

—Jeremy Singer, collaborator and assistant professor at the National Laboratory for Agriculture and the Environment

One focus of the research was to measure if cover crops help replace carbon in the soil that would be lost as stover is removed. Using his own findings and examining previous research, Singer estimates that the Kentucky bluegrass treatment likely replaces as much carbon in the soil as stover would have, although he concedes that it is difficult to measure precisely.

The cover crops also provide at least 85% ground cover, meaning only 15% of the soil is exposed and susceptible to erosion, he said. The cover crops also provide weed and insect suppression during the corn growing season, according to researchers.

To reduce competition between corn and Kentucky bluegrass, Moore said bluegrass needs to be chemically treated in the spring to force it into dormancy while the corn gets started.

Generally the two species co-exist well, said Moore, noting that ecosystems have been growing two or more plants in one field for millennia. Prior to the Midwest becoming an agricultural powerhouse, the land supported many different species of plan—each performing different functions for the soil and water quality. Now,there are just a few plant species dominating the landscape, each performing just one function, said Moore.

In this study, we are trying to put those functions into a simple, easy-to-manage system that can have positive environmental impacts.

—Ken Moore



Reduced erosion also means fewer nutrients washed into rivers with the soil.

If this sequelches the argument "removing stover means killing the soil", what's the future for harvested stover? Fuel, or additional fodder for ruminants (since corn is so expensive)? It's going to be interesting.


This could be an interesting solution to get a major source of cellulosic fuel feed stocks (from stover) without negative effects on cultivated areas. If it works as tried, more corn could be re-directed to produce human and animal food stocks.


How about planting some beans and squash as ground cover :)

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