Research Reveals Beneficial Impact of Cover Crops on Water Quality in the Mississippi River Basin

By Sarah Carlson, Practical Farmers of Iowa

EAST LANSING, MI -- New research by a multi-state team of agronomists working with the Midwest Cover Crops Council (MCCC) suggests that up to 19 million acres of corn and soybean ground in the upper Mississippi River Basin has the potential to incorporate cover crops, which would decrease nitrogen entering the Gulf of Mexico by up to 400 million pounds. At current prices, that nitrogen is valued at $160 million.

The research, published in the July-August 2014 issue of the “Journal of Soil and Water Conservation,” looked at the potential to plant cover crops and the resulting decrease in nitrogen loss from farm fields in 10 counties spread across five states (Ohio, Indiana, Illinois, Iowa and Minnesota), as well as the Midwest region as a whole. The counties are located in watersheds that flow into the Mississippi River Basin and contribute to low oxygen zones that become incapable of supporting aquatic life in the Gulf of Mexico.

“The potential for adopting cover crops in these critical watersheds is substantial, and cover crops should be considered as one of the primary conservation practices to improve water quality,” says lead researcher Eileen Kladivko, professor of agronomy at Purdue University.

The researchers used data on available land, crop rotations and tillage systems in the areas studied to develop computer models that simulated the feasibility of planting cover crops. Potential water quality benefits were estimated for agricultural land with artificial drainage systems installed. The modeling scenarios looked at multiple cover crop species, but winter cereal rye was studied the most because of its comparatively widespread use: While adoption is less than 2 percent, it is the cover crop species most commonly planted by Midwestern row crop farmers.

Researchers say that tillage practices, some of which make it easier to plant cover crops, and the challenge of planting cover crops during the fall harvest season – timing that is necessary to successfully seed and establish the cover crop – are some of the reasons why the cover crop adoption rate is low.

“Cover crops are easier to integrate into no-till and strip-till systems,” Eileen says. ”In contrast to a full-width tilled system, they allow earlier planting in the fall and more time for cover crop growth in the spring before terminating them with herbicides.”

Study co-author Tom Kaspar, a research scientist with the USDA Agricultural Research Service National Laboratory for Agriculture and the Environment, says cover crops are worth pursuing in spite of these challenges because of the numerous benefits they offer.

“We realize that farmers have a lot on their plates and that our estimates for potential cover crop use don’t consider other factors like costs, labor and logistics,” he says. “But, we all know that we need to do a better job reducing nitrogen losses, and cover crops are one of the few practices that will do that, plus protect soil from erosion and improve soil health at the same time.”

Other researchers involved in the study include soil scientist Dan Jaynes and agricultural engineer Robert Malone, both with the USDA-ARS National Laboratory for Agriculture and the Environment in Ames, Iowa; Jeremy Singer, a former research agronomist at the USDA-ARS lab; Xenia Morin, associate dean in the School of Environmental and Biological Sciences at Rutgers, The State University of New Jersey in New Brunswick, New Jersey; and Timothy Seachinger, associate research scholar at the Woodrow Wilson School at Princeton University in Princeton, New Jersey.

The researchers are all participants in the Midwest Cover Crops Council, a coalition of members based in nine states and the Canadian province of Ontario. The goal of the MCCC is to facilitate widespread adoption of cover crops throughout the Midwest to increase the productivity of soil resources and improve the ecological, economic and social sustainability of farming systems.

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Founded in 2006, Midwest Cover Crops Council is a diverse group including members from academia, non-governmental organizations, farmers, the private sector, and federal and state agencies that seeks to significantly increase the amount of cover crops on the Midwestern landscape. The MCCC works toward this goal by sharing current research, identifying emergent priorities for regional collaboration, discussing contemporary challenges preventing broader adoption of cover crops, and by exploring the possibility of a multi-dimensional partnership. For additional information, visit www.mccc.msu.edu.