By Jim Isleib, Michigan State University Extension
A replicated trial on a small farm in the north-central Upper Peninsula compared three cover crop selections and a fallow treatment. The project was funded by a Michigan State University Extension regional Project GREEEN grant. The cover crops included Marathon red clover, a hybrid sorghum sudangrass and a multi-species cover crop mixture from North Dakota containing soybeans, lentils, forage peas, sweet clovers, turnips, oil-seed radishes, pearl millets, forage oats and sunflowers.
The cover crops were planted on June 29, 2011, and allowed to grow through the year with livestock grazing simulated by mowing off about half of the sorghum sudangrass and multi-species mixture in late September and leaving the mown material on the plots. This grazing was included to reproduce the way similar multi-species cover crops are currently managed on North Dakota farms.
After rototilling the cover crops in the spring of 2012, oats were planted. Oat yields were compared in August 2012 to determine the impact of the different soil-building cover crops after one year. Soil samples were also collected from each treatment before the trial, following the cover crop and following the oat crop. Soil test results were used to monitor soil fertility indicators, but were not meant to be conclusive and were not subjected to statistical analysis. No fertilizers were used in the trial.
Oat yield following the cover crop treatments in this trial gives a single indication of the impact of a single year cover crop treatment. Other factors, including weed suppression, were not included in this trial. This two-year trial was not expected to result in dramatic changes in crop yield or soil conditions. Cover crops are understood to be a long-term investment in soil health and crop performance with benefits becoming more apparent over several seasons.