A few weeks ago I wrote about early termination of cover crops, especially cereal rye ahead of a corn crop. Recently I came across a field research report from the Practical Farmers of Iowa that presented information from 3 farmer research trials in 2014 and 2015 that looked at the timing of planting soybeans into a terminated cereal rye cover crop. Since soybeans are a broadleaf, it may be advantageous for this crop to let cereal rye get more growth before terminating the crop. The alleopathy effects of cereal rye on other grasses could be a benefit to soybean production.
The on-farm studies were set up as replicated strips designed to compare early cover crop termination versus late cover crop termination. All soybeans were planted on the same day. All cover crops were terminated with herbicides. Some cover crop strips were terminated 10 to 14 days before planting and other strips were left to grow and accumulate more biomass until termination 1 day before planting.
Two of the three farmers saw no difference in yields between the two termination dates. One farmer saw a small yield reduction with the later termination date (more cover crop growth) but felt that the extra growth protected his soil from some serious soil erosion losses during the heavy rains experienced in the 2015 cropping year. One of the farmers also credited the late termination date with suppressing weeds and reducing his herbicide expense.
The complete report is available on-line at: http://ow.ly/10DGca and can be downloaded as a pdf file. As knowledge about how to use cover crops in a system continues to grow I am interested in hearing about any local experiences and stories.