Study shows cover crops may increase yields over time

Farmers need more research showing cover crops increase yields, reduce erosion and add nutrients back to the soil in corn-soybean rotation before they adopt the practice, says University of Missouri researcher Ranjith Udawatta.

Few farmers in the Corn Belt, especially Missouri, have adopted the practice, says Udawatta, a research professor in soil, environmental and atmospheric sciences. He hopes his research and that of others encourages policymakers to consider cost-share programs with incentives to adopt the use of cover crops.

Udawatta and other researchers, including MU Extension agronomist Dhruba Dhakal, conducted a four-year study at a soil health demonstration farm in Chariton County in cooperation with the Chariton County Soil and Water Conservation District, Associated Electric Cooperative Inc. and the USDA Natural Resources Conservation Service.

The researchers used legume and non-legume cover crops on wheat-corn-soybean and corn-soybean rotations on claypan soils. They compared input costs and yields to analyze benefits.

Udawatta’s study included 2012 and 2013, which were marked by drought and poor growing conditions. In 2014, fields planted with cover crops showed an average 8 percent increase in corn yields compared to similar test fields not planted with cover crops. This resulted in a 30 percent increase in revenue per acre. However, a 37 percent increase in cost per acre offset that revenue. As a result, profits went down 33 percent.

In the next year, revenues and yields went up and researchers reduced input costs. Udawatta believes that revenues increase and costs decrease over time through use of cover crops.

Use of cover crops is important in Missouri, where row crop farming lacks diversity, Udawatta says. Farmers devote most of their acres to soybean, corn and wheat. The lack of diversity reduces soil productivity and increases pest and disease pressure. It also reduces weed control.

Most nutrient loss occurs when soils lie bare after harvest. Cover crops benefit the soil during fallow periods by adding nutrients and reducing erosion, Udawatta says.

Farmers’ acceptance of cover crops depends upon proven economic returns, he says. In a 2007 survey, more than half of the surveyed farmers said they would plant cover crops if a cost-sharing program were available.

Udawatta points to a 2013-14 cover crop survey conducted by USDA’s Sustainable Agriculture Research and Education program and the Conservation Technology Information Center. The SARE survey reported data from more than 2,000 farmers. It showed that cover crops significantly increase yields in the first year of use. Yield increases for corn were 6.35 percent and soybean yields increased 7.95 percent.

Other members of the research team include Zhen Cai, Clark J. Gantzer, Shibu Jose and Larry Godsey. The study is through MU’s Center for Agroforestry, MU School of Natural Resources and Missouri Valley College Agri-Business.