Let’s Discuss Cover Crops

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Cover crops are plants grown in fields and gardens between “main crop” production. Cover crops typically provide benefits to the soil at the root level helping form soil aggregates, providing structure to the soil system. Additionally, cover crops can increase microbe diversity and activity, reduce weeds, and protect the soil from erosion. When a cover crop is terminated soil microbes begin to breakdown the biomass; a by-product of their digestion is poly saccharides, complex sugars that act as a “glue” to help hold small particles of soil together. Farmers and gardeners can see this impact with the naked eye and call this attribute in soil, ‘crumby’ and note that crumby soil has good aeration. Just as traditional crops are organized bySARE publication: "managing cover crops profitably" plant families, cover crops can also be organized into plant families. When deciding on which cover crop to plant in between crops, consider that cover crops belonging to different plant families offer differing benefits. If these cover crop facts peaked your interest, consider the source of this material, a recommended reference: the SARE publication: Managing Cover Crops Profitably. This resource is available for free as a download or for purchasing as a hard copy.

In a past interview with a Pfafftown, NC farmer, the N.C. Cooperative Extension received a good working definition of cover crops in use while visiting a cover cropped field.

‘In the summer there were tomatoes here. Afterwards, Elliot sowed oats, sudan grass and clover. We’re talking about cover crops. Emma envisions sunflowers for the coming spring, a different cover crop. “Just to look at,” she laughs. Emma crouches down along one row and goes to pull up another cover crop example, a radish. “The radishes are a little ‘freezy’. Ah, here’s one. It’s a no-till way of bringing nutrients from the bottom up. The root helps aerate the soil. The tops are also a great green manure/ biomass. This isn’t to eat. It’s a cover crop, just to feed the soil. Cash crops versus cover crops: One is sold in the market. The other sustains the soil. I hope that more people are learning more or are remembering more about this relationship.”’ Read more from this interview

radish cover cropWoman in a field of radish.

Cover crops were the bookend lesson to the 2023 Forsyth County Urban Farm School. Forsyth County Urban Farm School is an intensive 12 week, hands-on class for individuals motivated to develop farms to grow and sell produce. Half of the program’s sessions are held in a garden, applying principals first hand. After the class’s harvest was completed in late July, 2023, plans to plant a cover crop were put into place. To review: A cover crop can be used to help increase or maintain organic matter, increase nitrogen in the soil, prevent soil erosion, compete with weeds, and/or maintain soil nutrient levels during winter months. After gleaning we cleared our plot of weeds to allow the cover crop seeds the opportunity to get established. This year we planted buckwheat as our cover crop.

There are many cover crop options and that decision is based on your goals for your growing space. Read up here to learn about hundreds of different options Or check out this cover crop selector tool.

When asked why buckwheat was chosen for this time and place, Forsyth County Horticulture Agent, Celine Richard gave the following insight. The time of the year is late July, almost August and the temperatures are high. Buckwheat can germinate and go to flower in as little as 6 weeks. Once your spring or early summer crop is complete, this cover crop can be planted in between crops and provide benefits with a short turn around time. Richard warns that when buckwheat flowers it goes to seed quickly. Within a week of when those flowers start to form. Therefore, If you want to avoid seed setting, the buckwheat crop should be terminated by mowing or crimping. If you prefer tilling, that method will work as well but should not be your only strategy for soil maintenance in the garden. One additional consideration for cover crop termination. When rolling or crimping a cover crop there is a slower release of nutrients from the biomass. When chopping, flaying, or tilling the cover crop there is a faster release of nutrients. In the case of buckwheat, the major nutrients taken up by the plants are phosphorous and other minor nutrients which are then released back into the soil during decomposition.

Cover crop planting: Buckwheat

Broadcasting Buckwheat cover crop seed

The next season of transplants can be directly planted into the mown or crimped cover crop. In this case, the buckwheat will act as a green mulch as it breaks down. To expediate the cover crop breakdown, a tarp can be laid across the cover crop after termination for a period of a few weeks.

Regarding irrigation, cover crops generally don’t need drip lines or other supplemental irrigation. Cover crops are seeded more heavily than production crops. Our garden plot had drip lines already in place. These were maintained and left on to a few minutes a day to ensure that the cover crop gets consistent moisture for more consistent germination.

In addition to soil health benefits, cover crops like buckwheat serve the pollinators in the ecosystem. Honey bees and native pollinators gravitate to buckwheat as a pollen and nectar source when allowed to flower. The shallow white blossoms attract beneficial insects that are predators of garden pests like aphids & mites.

Bee lands on Crimson Clover and Hairy VetchMacro image of Buckwheat

If you are new to cover crops here’s an article on cover crops for home gardeners. and a quick video on cover crop benefits from Southern SARE for growers large and small.

If you have questions about cover crops for your garden, please contact the N.C. Cooperative Extension, Forsyth County Center, Horticulture Agent, Celine Richard, cvrichar@ncsu.edu, 336-703-2869.