How do you choose the best cover crops for your corn and soybean fields? Each cover crop option has its own unique characteristics, and your job is to determine which ones match up best with your conditions, location, goals and timing requirements.
We’re here to help you make your decision. Here’s a list of the most popular Midwest cover crop options.
📷by mvburling from Getty Images via canva | Rye and clover cover crop.
USDA Agricultural Resource Management Survey data shows that rye and winter wheat are the most common single-species cover crops grown in the U.S. In 2021, 44% of corn acres used cereal rye as a cover crop, about twice the number of acres using winter wheat. The case was the same for soybeans in 2018 (the most recent data available): 48% of soybean acres growing cover crops were planted with rye, while 26% were planted with winter wheat.1
Rye is often used for erosion control, forages, improved soil health and weed control. A rye cover crop is often planted after corn and ahead of soybeans. This is a good fit since soy is often planted later than corn, which gives rye more time to introduce organic matter into the fields. Rye is a winter-hardy cover crop and as such is usually terminated before (or, if “planting green,” shortly after) planting of the next cash crop.
📷by mvburling via canva | Winter rye and clover cover crop
If you intend to plant a cover crop before planting corn, your options generally fall into two categories: winter-kill species and winter-hardy grains.
Broadleaves: This category of cover crop includes brassicas, mustards and other plants. They have a low C:N ratio (< 20), meaning these plants decompose quickly when naturally terminated by freezing temperatures, rereleasing nitrogen rather than immobilizing it in the plant or microbes.2 They also work well in no-till fields.
Drawbacks include lower ability to accumulate growth or “biomass” and the potential for residual herbicide to kill or stunt cover crop growth.
Oats: These plants function similarly to broadleaves with two exceptions. Oats are easier to establish; however, they are more difficult to seed aerially.
Cover crops in this category include cereal rye, wheat, triticale and others. Winter-hardy crops can help manage weeds, reduce soil compaction and provide food for microbes while uptaking residual nitrogen.
Drawbacks include a high C:N ratio (if not terminated early) and the potential to tie up some nitrogen, which can be detrimental to growing corn. They can also increase the risk of harm from sources like Pythium.3
Another downside is the time and labor required to terminate winter-hardy cover crops.
Unlike the options you face when choosing a corn cover crop, there is only one category of recommended cover crops to plant before soybeans: winter hardy grains. Among options like wheat and triticale, the USDA recommends using cereal rye due to its consistent ability to grow excellent roots, build soil composition and scavenge excess nutrients.
Resources are available to help growers discover which of the many cover crop options might work best for their circumstances.
The USDA’s Cover Crop Chart includes information on 70 cover crop species, with details about their growth cycle, relative water use, plant architecture, seeding depth, forage quality, pollination characteristics, and nutrient cycling.
The Midwest Cover Crops Council offers their Cover Crop Decision Tools, a robust online resource that offers expert cover crop information and recommendations based on growers’ specific goals and is keyed to their specific location, down to the county level.
Cover crop choices and timing decisions can be highly variable based on many different factors. If in doubt, have a conversation about your specific operation and goals with your local ag retailer or university extension agent.
Read more about cover crop termination and weed control at Grow Smart® Live:
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Corn
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January 8, 2025
Soybean
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