Pick the most effective cover crop termination strategy. Learn which method and timing will best support soil health, residue management and a strong spring season.
While there are several good options for terminating cover crops, it's important to understand which cover crop termination methods work best for your specific cover cropping system and overall operational goals.
Cover crop termination methods
Six common approaches are used by most farmers when terminating cover crops. Here's how they work and under which conditions.
Herbicides for terminating cover crops
In most cases, cover crops should be terminated before planting corn, soybeans or other crops. In general, experts recommend terminating cover crops 10-14 days before planting corn. That time window is less important for soybeans, though research suggests termination within one week of planting is often ideal.
Herbicides such as glyphosate and 2,4-D are commonly used when terminating cover crops. Contact herbicides tend to work best on small annual plants. If you plant multiple cover crop species together, you might need to use several different herbicides.
Tillage for terminating cover crops
Balance cover crop termination methods with good soil health practices. You can kill cover crops by mechanically uprooting them or disturbing the soil. Moldboard plows and chisel plowing are most effective for terminating cover crops and managing crop residue, but they can also damage soil structure, so tillage should be used mindfully.
Mowing for cover crop termination
Although mowing can reduce cover-crop biomass, it's not an ideal termination method. Cutting must remove all plant growing points, many of which are often below ground during the vegetative stage. Always combine mowing with other methods to ensure full termination.
Roller crimping
Roller crimping involves mechanical flattening and crimping to kill cover crops without the need for herbicide application. Work with a trusted adviser to determine when you should do this to consistently kill plants, particularly if you plant multiple cover crop species. Roller crimping is often used in conservation tillage or no till cover crop termination environments. It's especially effective with covers such as cereal rye at the post-pollen shed stage.
Harvesting cover crop as silage
Turning cover crops into livestock feed is another viable option. Benefits of this approach include cost savings on forage, consistency of forage supply and even livestock weight gain comparable to pasture grazing.4 For maximum efficacy, time your harvest to maximize the nutritional quality and biomass. Also be aware of tradeoffs: Your soil residue cover might decline, and you'll have less available residue to decompose and contribute to soil organic matter.
Grazing livestock on cover crops
As with silage harvesting, livestock grazing can bring benefits and tradeoffs. Benefits include the ability to quickly terminate covers and reduce biomass. Tradeoffs include reduced soil residue coverage, lower residue benefits and the need to provide proper fencing.
