How to Improve Soil With Compost and Cover Crops

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Buckwheat is a fast growing summer cover crop.

Buckwheat is a fast growing summer cover crop.

As you get ready to plant this spring, don’t forget to add organic matter to the soil. Organic matter, such as compost, improves all soil types, resulting in naturally healthier plants. You can purchase compost in bags or in bulk or make your own at home with yard debris and kitchen scraps. You can even grow your own by planting certain cover crops, known as green manures, and tilling them into the soil.


You can purchase compost and soil conditioners in bags from garden centers or by the truck load from mulch dealers. This can get expensive, especially considering compost should be added to vegetable beds each year. As an alternative, you can make your own compost free at home. In fact, you may be throwing away the materials you need to make this valuable garden resource.

Composting is simply the act of helping natural materials such as leaves, grass clippings, and vegetable scraps to break down. Composting methods can be grouped into two categories: passive or active. Passive composting methods allow nature to do most of the work, but take a lot longer to get a finished product. In passive composting, raw materials such as leaves, straw, grass clippings, and vegetable scraps are stacked into a free standing pile or placed inside a composting bin and allowed to break down on their own over the course of two to three years. This method produces good compost, just not very quickly.

Active composting can produce ready to use compost in as little as two months, but takes more work on your part. In active composting, raw materials are made into a pile similar to passive composting, but then the pile is turned every week to encourage rapid break down.

To build a compost heap, pile green and brown materials in 3”- 4” thick alternating layers in a free standing pile or inside a compost bin. Examples of brown materials include leaves, straw, newspapers, and wood chips. Green materials include vegetable scraps, grass clippings, plant debris, coffee grinds, and animal manure, but avoid pest waste, which can contain harmful bacteria. A few other things that should not be added to compost piles include meat and bone scraps, dairy products, grease or oil, perennial weed roots like Florida betony or dollarweed, and diseased plants, since the pile may not reach high enough temperatures to kill plant disease organisms.

Make sure to water each layer as you stack it so the finished pile has the moisture content of a damp sponge. Turn the pile every 5 to 7 days until you can no longer recognize any of the original materials because they have all broken down to a crumbly brown soil like consistency that has an earthy smell. This should take two to three months. To mix compost into the soil, spread a three to four inch layer over the surface of your garden and then till in six to eight inches deep.


Green manures are cover crops that are seeded directly into empty garden areas, allowed to grow for several weeks until they reach bloom stage, and are then tilled into the soil. Tilling crops into the soil adds nutrients and increases organic matter, and is much like growing compost directly in the garden.

Two of the best summer green manure cover crops for gardens are buckwheat and southern peas, also known as cowpeas, crowder peas, or black eye peas. Both of these crops can be seeded directly into gardens from mid-April through August at a rate of two to three pounds of seed per thousand square feet of garden area.

To grow these crops, till and rake the soil level, scatter seed over the surface, rake in lightly, water, and stand back! Allow the crops to grow until you start seeing flowers, at which point you can till them directly into the soil or mow them first and then turn them under. For buckwheat, this should take one to two months. For southern peas, plan to allow them to grow for two months or more.


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