Planting several types of cover crops together can provide more benefits than a single species will, but farmers can’t just throw anything they want into the mix.

“Figure out your goals and purpose. What are you trying to accomplish?” asked Sarah Hirsh, a University of Maryland Extension agent in Somerset County.

Hirsh spoke in the Feb. 10 Wednesday Webinar series offered by MidAtlantic Women in Agriculture.

Each cover crop species has its own traits that may or may not contribute to a farmer’s goals for the cover crop — scavenging for nutrients, controlling weeds, producing biomass, building organic matter, breaking compaction, preventing erosion, or yielding a cash crop or forage.

Variables to Keep in Mind

When rye is grown after corn but before soybeans, the voluminous cover crop reduces weed pressure in the soybeans. But adding a legume cover crop wouldn’t make sense, Hirsh said, because soybeans can fix their own nitrogen.

Some species work better in mixes than others.

Winter radish is good at weed control, but it may also outcompete other species in a cover crop mix.

Even the same crops can have widely different results depending on planting dates, weather or other factors.

When designing a mix, farmers need to consider species that have compatible planting dates, frost tolerance, competitiveness, seeding depths and methods, growth habits, soil moisture, and fertility needs.

Cover crop mixes are complicated and farmers shouldn’t be afraid to be less than perfect, Hirsh said. She suggested that farmers experiment and start small.

“Focus on purpose and practicality first,” she said. “Start small and try things out. See what works where you are and don’t be afraid to fail. No book on cover crops can teach you as much as growing them in the field.”


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