How do single species cover crops compare to mixtures when considering impacts to water quality and crop yield? On Wednesday, Emily Waring, Graduate Research Assistant at Iowa State University, presented results from a research project that has been carried out at six Iowa State University research farms from 2013 – 2018.
The research project compared oats and a mixture of oats, hairy vetch and radish before corn to a control site where no cover crops were used before corn. Before soybeans, the cover crops used were cereal rye and a mixture of cereal rye, rapeseed and radish, which were again compared to a site where no cover crops were used before soybeans.
Waring’s take home messages were:
- Corn and soybeans are fundamentally “leaky” – cover crops can fill the void in the brown months (before cash crop planting and after cash crop harvest)
- Nitrate concentrations were significantly reduced with the use of cover crops – with the highest reductions seen when using rye and oats
- Corn and soybean yields were unaffected by the use of the cover crops
- Rye and oats provide the best biomass return on seed investment
The research project results show that single species perform well, when when looking at water quality improvement and crop yield. The cover crop species mixtures were more expensive and did not perform better than the single species at reducing nitrate and improving water quality, however Waring stated that there are likely more benefits to diversifying mixtures that aren’t reflected in this study. Future research will look at the soil health benefits of using cover crops and will compare the use of single species vs. mixtures when improving soil health is the goal.
To learn more about the research results, watch the full webinar here.
Join us next month, on Wednesday, June 19 at noon, when Chris Hay, Senior Environmental Scientist at the Iowa Soybean Association, will present an Iowa Learning Farms webinar titled “Drainage Water Recycling: An Emerging Conservation Drainage Practice”.