When lower biomass cover crops are part of the equation, the general rule for terminating cover crops is 10 to 14 days before soybean planting. This gives biomass time to begin breaking down and reduces the chance of planting into wet, matted residue. Early termination also helps avoid pest or disease issues linked to a “green bridge” between crops.
Thinking of planting green? More farmers are planting green, but making sure your equipment is prepared for heavy residue and monitoring soil moisture closely to avoid cool, damp seedbeds is key. If this is your first year planting green, we recommend only trying it on a small number of acres for the first year. Then you can expand in the following years as you learn more about what worked best for your operation. We also recommend terminating shortly after planting, rather than before, when planting green.
- Know Your Cover Crop
Different cover crops behave differently in spring. Here’s a quick rundown:
- Cereal Rye: Missouri’s go-to cover crop. Easy to terminate with glyphosate and great for weed suppression. If using cereal rye ahead of corn, we recommend early termination to avoid issues with seed placement and nitrogen tie-up.
- Legumes (e.g., crimson clover): Generally, legumes boost soil health and naturally fix nitrogen and improve soil fertility.
- Brassicas (e.g., radish, turnip): Often winter-killed, but scout your fields—some may survive.
- Pick the Right Termination Method
Most Missouri soybean growers rely on herbicide termination, but there are other tools in the toolbox depending on your system:
Common Termination Methods:
- Herbicide (Glyphosate): Most effective when cover crops are actively growing. Add AMS and surfactants as needed.
- Roller Crimper: Works well on mature cereal rye.
- Mowing or Light Tillage: Less common but may be used if conditions limit chemical or mechanical options.
- Keep an Eye on the Weather
Missouri springs can be unpredictable. Temperature and moisture can impact how well termination methods work:
- Cool temps can reduce herbicide uptake.
- Wet soil may delay termination or field entry.
- In dry conditions, living cover crops can remove moisture from the soil that you would’ve otherwise relied on to get your cash crop germinated and growing. Always check the 7-day forecast before making a termination pass.
- Prep Your Planter for Residue
Heavy or inconsistent cover crop residue can interfere with seed-to-soil contact, planting depth, and emergence. Before planting:
- Make sure row cleaners are working properly
- Double-check closing wheels for pressure and contact
- Be aware of hair-pinning in high-residue situations
Planter setup is just as critical as your termination timing.
- Align Termination with Your Herbicide Program
Your spring cover crop kill must also fit into your weed management strategy. For example:
- Don’t tank-mix glyphosate with products that may reduce its efficacy
- Wait until the cover is fully terminated before applying residual herbicides to ensure you get soil contact
- Watch for crop rotation restrictions when selecting herbicide products
A clean, effective kill is step one—think long-term as you build your weed control plan.
Cover crops can be a huge asset to Missouri soybean fields—but only if they’re terminated properly. With careful timing, the right method, and a little planning, your spring termination can set the stage for a strong, healthy soybean crop.
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