Published Mar 17, 2015

RESEARCH REPORT: Green manure cover crops established with small grains
By Stefan Gailans

Extending and diversifying a crop rotation to include a small grain presents farmers with the opportunity to also include green manure cover crops. These green manures can be seeded with the small grain or, alternatively, can be planted directly after small grain harvest in July. Three farmer-cooperators participated in a two-year trial in which each of them grew a small grain + red clover and a small grain + cover crop mix preceding corn in their crop rotations. The results of the trial can be read about in the report entitled, “Green manure cover crops established with small grains.”

This trial was conducted in 2013-2014 by Dick Sloan near Rowley in Buchanan County, Vic Madsen near Audubon in Audubon County, and Bill Buman near Harlan in Shelby County.

dick sloan drilled spring red clover into rye 2013

Red clover drilled into cereal rye at Dick Sloan’s farm in 2013.

planting into dying cloverSloan

Dick Sloan planting corn into red clover green manure in 2014.

Among the key findings:

  • Red clover frost-seeded with the small grain put on more aboveground biomass and contained more N than the cover crop mix seeded after small grain harvest on one farm.
  • Corn yields following red clover were greater than those following the cover crop mix at only one farm.
  • If sufficiently terminated, red clover and the cover crop mix preceding corn in rotation can result in yields comparable to county yield averages.

This project is supported in part by the Iowa Department of Agriculture and Land Stewardship, Division of Soil Conservation, the Leopold Center for Sustainable Agriculture and the Walton Family Foundation. For more information about this study and other studies involving small grains and cover crops as part of PFI’s Cooperators’ Program, contact Stefan Gailans at stefan@practical farmers.org.

The full report can be read here.