The first step in selecting cover crops should be to ask yourself some questions to help clarify your goals for using cover crops. Questions like… Do you want to reduce erosion? Build soil organic matter? Reduce compaction? Scavenge nutrients? Provide forage? Or a combination of things? In addition to helping us select cover crop species and mixes, our cover cropping goals also help us set a bar for what we consider a cover crop “success”.
Different goals require different cover crop species or species mixes, for example:
- Grass species, due to their prolific root systems, are often used for erosion control and to build soil organic matter.
- Brassicas can have significant fall growth to help with late season erosion control, they can additionally provide forage. The addition of brassicas can also help to diversify the types of plants in your crop rotation and this can help to diversify your soil microbial community.
- Legumes are typically used a cover crop or in a mix when we want to add nitrogen to the cropping rotation to offset fertilizer nitrogen
In additional to selecting cover crops to meet your individual goals, every farm has different crop rotations, equipment availability, herbicide programs and manure availability.
After which cash crop will you be planting cover crops?
While there are dozens of cover crop species available, our choices for cover crops species that will be successful are often dictated by what crop we will plant the cover crops after. For example, there are many choices for cover crops following winter wheat, choices become fewer after corn silage and narrow to a very limited field of species choices following soybeans and corn grain.
How are you going to seed the cover crop?
What equipment do you have available? Many agree that getting the seed in the ground (seed-to-soil contact) is optimal, particularly in coarser textured soils. Drilling of cover crops generally provides the best soil-to-seed contact, but if drilling is not an option, broadcasting with light incorporation can result in good stands in the right situation. Surface broadcast applications without incorporation, by ground or aerial equipment, may work better in moderate to heavy textured soils where the seed has better access to soil moisture, particularly when rain events aren’t timely.
If seeding cover crops into a standing crop, timing of seeding is key, as young plants will need to access to adequate sunlight to begin photosynthesizing shortly after germination.
Go to this page to look at specific recommendations for the various planting methods.
What herbicides have you used in the year (or two) prior to planting the cover crop?
This may be one of the most important questions you ask yourself, particularly if you plan on using your cover crop as forage. Herbicide carryover can compromise your cover crop stand and/or make it ineligible for use as feed. Be sure to thoroughly read the herbicide labels and understand any planting or feeding restrictions.
How are you going to terminate the cover crop?
For many, selecting species that (usually) winterkill can relieve some of the anxiety of trying covers for the first time. If you would like the cover crop to continue to grow over winter and into the spring, be sure you understand the spring management and termination requirements.
Pay particular attention to the suggested timing of termination in regards to cover crop growth stage and any potential allelopathy effects of the growing covers.
Do you apply manure in the spring and/or fall?
Once you’ve considered these questions, then selecting cover crop species for your farm becomes a bit easier. Talk with those who have tried cover crops and been successful or have encountered challenges. As knowledge is often best gained through experience, build upon the experiences of others. But no matter what you do, when trying cover crops for the first time, start with a limited number of acres. Success breeds success, so start small, determine what is going to work for your farm and build from there!