Cover Crops

I have talked about cover crops briefly in the past, but this week I’d like to go into more detail. Planting cover crops year after year provides many benefits to the soil. Let’s talk a little more about what a cover crop is, why you should plant one, and how to go about doing that.

A cover crop is a crop that you plant to cover the ground. (How’s that for using the word in the definition?) Most of the time cover crops are planted in the fall and grow through the winter to be
terminated in spring before you plant your garden. There are summer cover crops that can be grown, but I’m going to focus on winter cover crops, because of the time of year right now. Typically, a cover crop is a cereal grain (e.g. rye, or wheat), brassica (e.g. forage turnip or wild radish), or a legume (e.g. clover or vetch). You can also plant combinations of the three.

Cover crops benefit soil health in a multitude of ways. One of those is that cover crops help build organic matter in the soil. A cover crop like rye produces a lot of biomass, when that biomass is tilled into the soil before spring planting, it gives the microbes in the soil material to work on to turn into organic matter. Because of the rainfall and heat that we have in the southeast, organic matter will decompose faster than it’s created. Therefore giving those soil microbes materials to turn into organic matter will allow you to increase your organic matter over time.

Cover crops also reduce erosion. After pulling the crops that you had planted in the summer the soil may be left bare. A cover crop will protect that soil, and hold it in place to keep it from washing away. Cove crops can also reduce weeds. Some crops like rye will release chemicals that are like a natural herbicide. You can also use cover crops as a natural mat, that blocks sunlight, and so make it more difficult for weeds to grow. Certain cover crops like brassicas that produce a large taproot can be used to alleviate compaction. That large taproot will break up the soil and can penetrate hard layers in the soil.

All of these attributes make cover crops very beneficial to the soil. So how do you grow a cover crop? The ideal time to plant a cover crop is around Labor Day. If you’re planting a cereal grain, you’ll want to plant 3-4 pounds of seed per 1000 square feet. Brassicas need 1-2 pounds of seed per 1000 square feet. Legumes need a quarter pound per 1000 square feet because the seeds are very small. Legumes are able to fix nitrogen because they have a symbiotic relationship with bacteria. Therefore, it’s important to inoculate your soil with the appropriate bacteria if you’re putting out legumes. Allow the cover crop to grow throughout the winter. Depending on the cover crop that you use, you may need to add some fertilizer. 2-3 weeks before planting your summer plants, you’ll need to terminate the cover crop by cutting it and tilling it into the soil.

If you have questions about cover crops contact your County Extension Office or email me at Jacob.Williams@uga.edu.