New publication aids in selecting conservation

Jodi DeJong-Hughes

Published Thursday, May 31, 2007

The new University of Minnesota publication “Conservation Tillage Systems for Corn Following Soybeans” was developed to assist producers and crop consultants in selecting a conservation tillage system for corn in a corn-soybean rotation.

This free online resource presents results of on-farm yield trials conducted across southern Minnesota in 2004 and 2005, and provides management tips for conservation tillage. The research was conducted by regional and local Extension educators and staff from the Monsanto Corporation, working with cooperating farmers.

Conservation tillage is defined as tillage systems that leave at least 30 percent residue cover on the soil surface after planting. Reduced tillage systems have benefits other than soil conservation, such as increased water infiltration, increased or sustained organic matter content, increased water-holding capacity, and continued long-term productivity of the soil. They also require less capital investment in equipment and fewer field passes, which reduces the amount of labor and fuel used.

The findings: Climatic conditions varied across the state and between years during the study period. The findings we summarize show how conservation tillage can greatly reduce soil erosion, with minimal effect on crop yields and often at lower production costs than conventional tillage.

We found that with appropriate adjustments to crop management, conservation tillage offers a low-risk means of achieving substantial reductions in sediment and phosphorus losses from cropland to streams, rivers and lakes.

Corn grain yields were significantly affected by tillage treatments at six of the 10 sites during the record cool growing season of 2004. Average corn yields were largest at the sites that used chisel-plow-plus and strip-till during the 2004 trials. Other University of Minnesota research has shown that reduced tillage systems can have significantly lower yields compared with conventional tillage in unusually cool or wet growing seasons, especially when long-term no-till or reduced tillage systems are used.

In contrast, corn yields were not significantly affected by tillage treatments at eight of nine sites during the warmer-than-normal growing season of 2005. The 2005 trials demonstrated how reduced tillage systems, like strip-till, can produce excellent corn yields while maintaining adequate residue cover to protect the soil from erosion. These data show strip-till and chisel-plow plus having significantly greater yields than one-pass or no-till for corn.

For more details on the research, access the publication in the May 16, 2007, issue of Extension’s Minnesota Crop eNews, available at http://www.extension.umn.edu/cropenews/.

Jodi DeJong-Hughes is a crops educator with University of Minnesota Extension.