The past few weeks I’ve received several questions on fall planted cover crops. As we think about fall cover crops and cover crops in general, one’s goals determine what a person does. Because we’re limited after corn and soybean harvest with time before frost, our options are also limited too. I’ll share a few practical mixes for the fall.

A cover crop mix of oats and brassicas may be of interest for those wanting fall forage, erosion control, winter annual weed control, and/or a cover crop that terminates with frost. To obtain these benefits, planting now through Sept. 15 at the latest would be best. For those in corn/soy systems, an option could be to try flying on cover crop seed. Normally we see good results around 50% of the time. With the heat this week most likely pushing crops to mature faster and the moisture we’ve been receiving, this may be an option to consider this year. Seeding rates do need to be increased when broadcast seeding cover crops. One note, if you have traditionally seen a lot of crickets in your field, we have observed how they will eat newly broadcasted cover crop seed on the ground. Another note, some desiring nitrogen production have flown on hairy vetch either alone or in a mix with oats/brassicas. That can also be done, just note that broadcast seeding rates need to be increased (25-30 lb/ac for hairy vetch broadcast vs. 10-20 lb/ac drilled) which can make that seeding more expensive.

Goals of spring forage, erosion control, weed control, and nitrogen production without the concern of winter termination: winter cereal crops such as cereal rye and triticale with hairy vetch or Austrian winter peas are an option. For those needing a third species to comply with various programs, a brassica can be added at 0.5 lb/ac. Winter cereals or a mix of a winter cereal with hairy vetch can result in a great weed control program suppressing weeds like henbit and marestail. Vetch can suppress bindweed in fields.

On our farm, we seed a mixture of a small amount of rye with a higher rate of hairy vetch before our corn each year (15 lb/ac hairy vetch and 15 lb/ac of cereal rye). We’ve found this works for us in providing some diversity of root structure, good establishment, and a lower carbon:nitrogen ratio to allow the vetch to break down quicker. This year, we terminated pre-plant due to wanting to preserve soil moisture in a dry spring. The hairy vetch was just beginning to flower and I took biomass samples at termination. The results showed 120 lb N/ac in the biomass and we estimate around half of that is available the first season for the growing crop. We then no-till planted the corn into the vetch/rye stand which laid down like a mat for excellent weed control that is still seen today. We utilized melted urea as our nitrogen source in-season and one field only has 20 lb N/ac on it. All our corn fields are monitored by Sentinel Ag to view any plant nitrogen needs in-season. We also hoped the Sentinel data would show when mineralization from the cover crop was occurring. We did see that on the nitrogen sufficiency indexes after we’ve received some larger rain events that allowed for mineralization to occur.

As growers think about their goals and input costs for the next growing season, a cover crop may be a tool for a goal you have. Particularly, a cover crop like hairy vetch before corn is a way to help reduce nitrogen costs for the next growing season while also helping with weed and erosion control and providing other soil health benefits.