The Iowa Cover Crop Working Group (ICCWG) has wrapped up a two-year study evaluating planting techniques for the successful establishment of cover crop mixtures and single species in Iowa. We are grateful to our partners: Hagie Manufacturing Company, famer partner Tim Smith, and Iowa State University Northern Research and Demonstration Farm.
Replicated cover crop strips were established in fall of 2014 and 2015 to compare three different seeding techniques:
- above crop canopy using a high clearance interseeder
- below crop canopy using a high clearance interseeder (video of seeding)
- drilling after harvest
Evaluation was completed through fall and spring biomass collection and crop yield. A no cover crop plot was included in the replications as a yield comparison check strip.
The mixtures species were selected based on the upcoming crop and their winter hardiness. Because the species seeds are different sizes, a goal of one million seeds per acre was used for seeding calibration to provide a fair comparison between treatments.
Oats and rye win the day
Results show that earlier seeding with the high clearance interseeder resulted in more cover crop biomass, both fall and spring, than the later seeding with a drill. For Iowa, oats and rye work better than any other species tested at this time. The single species (oats and rye) resulted in more total biomass than the mixtures providing better soil erosion protection. Oats and rye were also the predominant species in the mixtures, accounting for the majority of the biomass.
There are no statistical differences in corn or soybean yields across the different cover crop treatments and no cover check plots. This yield neutral response following a cover crop is consistent with a long term ICCWG cereal rye cover crop project now entering its ninth year.
This research project was made possible with a State Conservation Innovation Grant through the Iowa Natural Resource Conservation Service.
The ICCWG includes core members from: Iowa Learning Farms, Practical Farmers of Iowa, Iowa State University Extension and Outreach, USDA-Agricultural Research Service, Leopold Center for Sustainable Agriculture, Iowa Department of Agriculture and Land Stewardship.