Mid-August is the beginning of the seeding window for successful cover crop seedings of common cover crop species in a corn and bean rotation. Farmers who are wanting to incorporate cover crops into their rotation should be finalizing their cover crop plans to ensure successful cover crop stands are established. Good fall growth of cover crops is key to achieving cover crop goals. To maximize fall growth of cover crops, seed early to maximize warm growing weather, and increase seed contact with moist soil.
Winter-kill cover crop species, like oats and radishes, have the most success when they are seeded early to maximize the amount of growing time. Early seeding windows require cover crops to be seeded into standing corn or beans which can be done with airplanes, drones, or highboy inter-seeders. Seedings into standing crops do not incorporate the seed into the soil, which can reduce germination of seeds, especially in dry conditions. When planning to inter-seed cover crops, consider the current soil moisture and precipitation forecast to improve germination. This year’s soil moisture and rainfall conditions are more favorable to inter-seeding than in past years.
Over-wintering cover crop species, such as cereal rye, have a longer seeding window and can be seeded after harvest with success. There are more equipment options available when seeding cover crops after harvest, however later planting dates will have fewer warm days to achieve desired levels of fall growth. Post-harvest seeding methods that maximize seed-to-soil contact will have quicker emergence and improved stands. Drills and planters ensure seeds are placed evenly into moist soil, ideal to ensure consistent cover crop stands. Broadcast seeded overwintering cover crop species that are lightly incorporated with tillage will see more consistent stands and quicker emergence than broadcast seeding alone. When incorporating cover crops with tillage, be sure to check seed depth as you go and not bury seeds past their recommended seed depths.
For those new to cover crops, consider your cash crop rotation when selecting cover crop species. For soybean fields that will be planted to corn in the spring, oats are the recommended species. Because oats will winter kill, spring termination will not be a concern ahead of corn planting. For corn fields to be beans next spring, cereal rye is recommended. These recommendations can be found with additional management considerations on the Midwest Cover Crops Council website under Iowa, in the cover crop recipes section.
For those looking for information on additional cover crop species and county-specific seeding dates, the recently updated Cover Crop Decision Tool on the Midwest Cover Crops Council website is a great place to explore cover crop species and plan seeding dates.
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- Conservation Field Specialist