Top 4 reasons you should consider cover cropping after wheat

Planting a cover crop after wheat can be very beneficial as part of your crop rotation as it can break up pest lifecycles and diversify soil microorganisms among many other benefits.

 

If you’re a wheat grower, what types of considerations have you made when it comes to post-harvest field management? If you aren't planting a summer cash crop after wheat, do you leave the ground fallow? You may not realize it but leaving your ground to sit fallow after a wheat harvest can have negative long-term consequences regarding soil health. Planting a summer cover crop after wheat can help you protect your soil from degradation, erosion, and competition from weeds.

Once you harvest wheat, there are eight to ten months where the soil is bare and unprotected. This allows for weeds, erosion, and soil moisture evaporation to occur due to the soil becoming exposed to direct sunlight. Many farmers feel that this isn't the ideal time to establish a cover crop, the ideal germination requires moisture and the right temperatures. It may surprise you to learn that the conditions directly after a wheat harvest tend to be perfect to get cover crop seeds in the ground.

Soil moisture is important for successful germination

When you plant a crop, germination includes five steps that happen in two weeks or less:

• Imbibition - the seeds absorb moisture, swell, and soften.
• Respiration - the seeds use the endosperm to sprout into a seedling.
• Effect of light on growth - light causes the seedling to further develop rapidly.
• Mobilization of reserves - the seedling will begin to mobilize or stabilize with the development of its metabolic process.
• Development of embryo axis - the seed then finishes germination with the extension of the hypocotyl or epicotyl. 

It's imperative to sow your cover crop within a day or two of wheat harvest while moisture is still available to begin this seed germination process.

When you do seed a cover directly after wheat harvest, there is less moisture than when planting your cash crop in the spring or fall. Because of this, it's important to understand how to protect your existing moisture for the cover crop to germinate successfully. You will need to take steps to seed with as little soil disturbance as possible by using a drill, planter, or by planting earlier by drone, air, or broadcast before the wheat is taken off. This allows the cover to be shaded and established well before being exposed to full sun.

Planting a cover crop on your wheat stubble can bring value to your operation by:

Cover crops will improve soil health

As plants go through the process of photosynthesis, they release root exudates into the soil that feed microbial life and return nutrition back to the plant. In longer-season crops, this root is readily available and constantly forming a relationship with the soil around it well into the fall season. In wheat crops, the plant will mature during the summer months and, as the weather cools, the root systems will slow and eventually stop their relationship with the soil. When this root is absent from the environment, microorganisms will begin to feed more on the available organic stocks around them, losing the benefit of a natural food source.

When cover crops are introduced at the end of the wheat lifecycle, their roots will take over where the wheat roots left off. They will form their own relationships with soil microorganisms and the process can continue. By having a living root mass all season long you can prevent soil degradation and keep a healthy soil ecosystem. 

Cover cropping after wheat can allow for a more diversified selection of cover crops

Planting cover crops after wheat can also allow you to diversify your cover cropping plan outside of a typical corn and soybean rotation. In other types of rotations, we are typically left with only a small window of time before winter arrives and fall-seeded cover goes into dormancy or terminates from the cold. Because of this, we are forced to use a more targeted list of available species to provide maximum soil health benefits under the time constraint.

When planting covers after wheat, we typically have a large summer window that can allow for a wider range of species to get properly started which can provide more nutrient scavenging. Cover crops, such as radishes and buckwheat, that are seeded immediately following a wheat harvest can provide great benefits. They can scavenge any additional nitrogen and phosphorus that the wheat crop may not have completely used, making these nutrients more available to the next crop in the rotation.

A wider selection of legumes can also be used such as crimson clover or vetch. These plants will fix atmospheric nitrogen from the environment. The longer growing period following wheat will allow them to produce more growth and provide a larger benefit.

If you’re looking to explore cover crops for your operation check out our article on selecting the right cover crop species. We’ve also provided a list of soil health tools to help you get started. 

Cover crops can help with weed suppression

When the ground is left fallow to allow for additional acres to apply in-season manure or the straw is baled for livestock bedding, summer weed infestations can be hard to control. Seeding a cover crop will allow those acres to be accessible to equipment for applications while also providing natural competition to invasive weeds that would otherwise require multiple herbicide passes. Introducing a cover species that can provide rapid and aggressive growth can act as a natural barrier preventing problematic weeds from having the moisture, nutrition, and space they need for proper growth. The cover crop can then use those resources to provide additional benefits to the soil instead of adding to the seed bank of noxious weeds. If you'd like to learn more about cover crops as a weed management too, check out this article.

Cover crops can return residue to the field after a wheat crop

In situations where the straw from a wheat crop is baled or harvested, planting a cover crop can return residue back to the farm. These types of cropping systems can provide an extra purpose in using the wheat residue, but you soils might pay the price. Nutrient removal increases as residue is harvested, so implementing a crop that scavenges excess nutrients and provides added residue to the system is important for the long-term balance of your soil.

Wind and water erosion also pose a risk to wheat acres. In environments with low residue, wind and water will damage the soil and often remove it from an environment. Providing a cover to hold soil in place with a root mass will prevent soil and nutrient losses from occurring. The plants can also provide protection from compaction during heavy rains. The cover can also provide a canopy that keeps soil temperatures at a healthier level for soil life, instead of a fallow situation where late summer heat can force soil temperatures to dangerous levels.

As with any cover cropping plan, getting started requires you to ask the question, “what reason am I implementing a cover crop?”. This not only helps you determine the purpose for a specific species of cover crops, but also details what success looks like for your operation moving forward with cover cropping. Whether your operation sees value in the soil health benefits, weed suppression, or increased residue, cover crops will be a clean and balanced resource for your operation. 

Below is a multi-species summer cover crop blend. Species include: buckwheat, Sudan grass, sunflower, brassicas, Sunn hemp, Millet

Further reading on cover crops:

https://www.cargillag.com/regenconnect/what-impact-do-c-n-ratios-have-on-residue-management-when-adopti

https://www.cargillag.com/regenconnect/keys-to-managing-cover-crop-grazing

https://www.cargillag.com/regenconnect/heathy-soil-is-more-than-a-good-idea