This week has been pretty exciting in the watersheds — we seeded two of our cover crop/tillage test-plot locations with cover crop seed into standing corn. It went really well! This far north, we need to give the cover crops as much time as possible to germinate and establish before things start freezing, so planting into standing crops gives us a multiple-week advantage. The timing has to be just right, however. Seed it too early, and the plant (often cereal rye where we are) will germinate but fail to capture enough sunlight through a dense canopy, which hinders good establishment. For corn, UW-Extension recommends seeding once the leaves have dried (senescence) from the ground up to and through the leaf below the ear. This is when we can count on getting at least 50% light at the soil level.
There are a few different methods for planting into standing corn. At our Pierce County test plots, hosted by farmers Brad and Roger Peterson, where the corn was standing around 12 feet tall, we used a high-boy seeder. The clearance of the boom was lower than the top of the corn, and we were all a little nervous about how it might affect the corn, but it turned out great — see the video below.
Many farmers in the area are also having success with aerial seeding, also done ideally at this point in the season.
For information on a different approach to interseeding cover into standing corn in Wisconsin (at V5, around mid July), check out this update from UW-Agronomy/Soil Science researchers: http://ipcm.wisc.edu/blog/2015/08/interseeding-cover-crops-into-v5-corn/.
And check back post-harvest for an update on germination and establishment.