Do you know what a cover crop is? A cover crops are essentially a group of plants that are specifically planted to help deal your soil. This includes issues such as soil erosion, nitrogen fixing, help with weed control and even improve water quality (SARE.org). You can also applies these principles in your own garden, find out more!
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Cover crops are a great way to build soil, nutrients and control weeds in both the agricultural and home gardening context. First, we will find out what a cover crop is. Then, we will explore some common cover crops.
What are cover crops?
Cover crops are crops that will not be cultivated and harvested like food producing crops. This includes plants like clover, hairy vetch and even a few edibles like field peas, daikon radishes and rutabagas. They are grow in a way to supplement the soil health rather than to be a finished product sold to consumers. Cover crops are also used as a mulch. Many people plant them then move them down using the clippings as mulch to prevent weeds and control moisture in the soil.
There are several different kinds of cover crops. Buckwheat, hairy vetch, annual rye, field peas, alfalfa, clovers and more all work on both large and small scale. All cover crops are designed to serve a purpose, or be multipurpose, in order to support the soil in which fruits and vegetables will grow in.
Why should I use cover crops?
There are many soil and plant health reasons to use cover crops, even in a backyard, raised bed garden. It is less applicable to container gardens due to the soil erosion and health concerns inherent in larger amounts of soil. I use cover crops for two main reasons in my urban homestead. First, to suppress the plants I do not want (also known as weeds). Second, to help supplement chicken feed. The chicken tractor moves around these cover crops and eat them and bugs in the soil while fertilizing the soil. We use annual winter rye to supplement the ground cover here in the south over the winter.
I am beginning to experiment with them in a new large, in-ground garden. Here in the south (northwest Louisiana) we have plenty of heat and long days during August and early September. During that time even the most heat tolerant and heat loving plants, such as squash and tomatoes, struggle. We are beginning to seed this area with cover crops prior to the fall so that it will freeze and die back into the soil.
All beans, peas, etc. fall into the legume family which is nitrogen fixing. They have excellent tap roots which bury deep into the soil to pull up nutrients. The legume family includes alfalfa, clover, chickpeas, beans, peas, soybean, lentils, carob, vetch and more. Legumes use the a bacteria called rhizobia that pulls nitrogen from the air into the plant and roots. This allows this family of plants to produce nitrogen rather than consume it like other crops.
In fact, legumes are an excellent companion plant as well since they fix nitrogen for plants near by. This can be helpful for heavy feeders such as tomatoes, cucurbits and others. Legumes are a key component of the indigenous “3 sisters method” of planting corn, beans and squash together.
Legumes used solely for a cover crop rather than for food can be grown then cut back, till under or smothered for the soil ready. They are also used as in pasture related agriculture such as a farrowed pasture that is healing from being eaten by ruminates, pigs and/or chickens. They help prevent soil erosion, fix nitrogen and allow for a diverse set of plants to take over the area and be ready for the animals at the next rotation.
Non-legume Cover Crops
The other major category of cover crops is all those outside of the special nitrogen-fixing legumes. However, you should know that there are often cover crop mixes with both legume and non-legume seeds in them that serve different purposes but are mixed together. They assist in other soil health applications such as reduce erosion, increase biodiversity and suppress weeds, sorghum is good for the heat of summer and suppresses nematodes.
Similar to the “cereals” you get from the grocery store, cereals are actually a type of grain used in cover crops. This includes annual rye, wheat, barley and oats. Each of these may serve a different purpose. According to Alabama Extension Office black oat helps suppress broad leaf weeds, cereal rye helps with soil erosion, build organic matter and help with water control.
It might seem counterintuitive to grow grasses to suppress, well, other grasses but it depends on your goal. The two most common are ryegrass and sorghum. These do many of the other beneficial soil related things such as building organic matter, smother weeds but they also help with excess nutrients. While you may want legumes to fix more nitrogen, too much nitrogen can be a problem. These cover crops can help with this by using up excess nitrogen.
Cover Crop Mixes
Most cover crop seed does not come in a single species seeding. You can find cover crops mixes to get the best advantages of all the different kinds. There are many places to purchase cover crops, including big box stores. However, you should look to those that specialize in commercial and market garden farming as they are trying to maximize the benefits in the most sustainable way.
Johnny’s Selected Seeds, Southern Exposure Seed Exchange and True Leaf Market all have excellent cover crop mixes, often in bulk to save on costs. There are many different mixes that have grasses, cereals, legumes and more to help with whatever issues you may be experiencing.
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