Benefits & Challenges of Planting a Cover Crop Ahead of Soybean

There are many reasons to consider planting a cover crop prior to planting a soybean crop in the spring. There are also many challenges that could cause some farmers to scrap that plan. Let’s have a look at both sides of the issue to see if cover crops can fit into your cropping program.

The benefits of cover crops are many and if possible, my recommendation is to bring more crops into a corn/soybean rotation. The advantages of planting cover crops ahead of soybean include:

1. Any cover crop adds diversity to soil by bringing its own set of beneficial “roommates”. These roommates are made up of animal, bacterial, fungal, and viral soil components that prefer a particular cover crop as their “host”. These symbiotic relationships help to build healthy, more productive soils.
2. Keeping the soil covered with cover crops during the fall, winter, and early spring months helps to “extend” the growing season which provides more opportunity for photosynthesis and the creation of biomass that can feed a grazing animal and/or be returned to help build the soil.
3. Many open fields are subjected to winter winds that move topsoil and remove valuable nutrients. Having a cover crop helps reduce water and wind erosion, hold winter snow, and improve water infiltration through the soil profile.
4. A cover crop such as cereal rye, which establishes quickly after planting, can help suppress the germination of winter annuals, providing a cleaner field to plant into in the spring (Figure 1).
5. Depending on growth, cover crops can provide feed for cows in the fall and early spring prior to planting.
6. During wet springs, fields planted with cover crops may be accessed quicker than conventionally tilled fields because their roots provide channels for water to infiltrate into the soil profile (Figure 2). As a result, soil structure can be more forgiving for field operations, including planting. 

Challenges of planting a cover ahead of a spring soybean crop can include:

1. Weather is the leading challenge as it affects the harvest window, moisture levels, and ground freeze dates. With a normal corn/soybean rotation, corn harvest may not be completed until November, which shrinks the fall/winter growth window of the cover crop unless seeded earlier into the corn crop. Wet soils can delay or impede cover crop planting.
2. Dry growing conditions provide their own set of challenges as farmers must decide if there is enough moisture for cover crop germination and if there is enough subsoil moisture to grow a cover crop without sacrificing next year’s soybean crop.
3. Termination is dependent on growing conditions leading up to planting. If wet weather is in the forecast, delaying termination until planting may be best to avoid a mat of wet residue that impedes crop germination. If soil conditions are dry and dry weather is forecasted, termination may occur about two weeks prior to planting the soybean crop to help prevent early competition for nutrients.
4. Fields with cover crops tend to be the last to warm up in the spring. Add in a cooler than normal spring and soybean germination can be abnormally slow.
5. Cover crops can attract insects that become seed feeders after soybean seeds are planted. Reduced plant populations could be the result.

Consider these pros and cons of cover cropping ahead of a soybean crop and decide if cover crops are an option for your operation. For questions like these and others, look no further than your local Channel Seedsman.

Channel Agronomist
John Goeden

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