Cover Crops for Your Garden
For vegetable gardeners, building soil fertility is extremely important. Soil fertility refers to conditions like nutrient levels, pH, soil texture and ability to retain enough moisture while draining excess water. The process of tilling, planting and harvesting can degrade a good situation in just a few seasons due to depleted nutrients, soil compaction and erosion. In order to keep the garden producing, a focus on good fertility is critical.
There are a number of ways to build soil fertility. You could go to the garden center and purchase fertilizer, lime, soil conditioner and other soil amendments to get the job done quickly. This can get quite expensive for large areas, and over time the soil will revert back to a less fertile state if not maintained. With that in mind, consider cover crops. A cover crop is simply a crop grown to help build soil fertility. These custodians of the soil should be used anytime there is a lapse between crops. There are lots of things that cover crops can do for the soil, depending on the specific plant or plants being used.
Nitrogen is the nutrient plants use to grow lush, deep green leaves and the primary ingredient in most fertilizers. Legumes fix atmospheric nitrogen (for free!) in nodules on their roots. When the crop is later incorporated in the soil, the nitrogen is released as the plant residue decays, feeding the ensuing crop. In cool weather, field peas, hairy vetch, crimson clover work well. In warm weather, cowpeas will do the job. While legumes do fix nitrogen, they do not increase soil organic matter as much as other types of cover crops.
Tap-rooted cover crops reach deep into the subsoil to break up packed earth and bring nutrients to the surface where they are accessible to shallow rooted crops. Plants like red clover (a legume) and long rooted radishes like diakon (a brassica) do things listed in other categories as well, but their uniquely long roots make them good choices to help loosen soils or to scavenge nutrients from deep in the ground.
Cover crops can help eliminate weeds. For most gardeners, weeding the garden is the least favorite chore. Cover crops can help smother weeds, therefore eliminate the need to weed the garden bed off season. Once planted, cover crops will grow fast to shade out weeds. Buckwheat, hairy vetch, and rye are all good smother crops.
Cover crops are used to absorb nutrients that would otherwise leach away with rain. Excess Nitrogen leached into our sewer systems can cause adverse health and ecological effects. Cover crops are useful after nitrogen fixing crops like peas or beans have been harvested and tilled in, to scavenge the valuable nitrogen those crops left behind. Some good options here include grasses, like annual ryegrass, wheat and oats; and brassicas like rape, radish, and mustard. These can be used individually or in combination with other cover crop plants. When tilled into the soil, these crops build soil organic matter for a fairly long term, and provide nutrients for the next crop.
While cover crops grow, their roots keep soil from compacting. After they are incorporated into the soil, the residues of cover crops keep the soil open as they break down and the roots of the ensuing crop develop. For the same reason, cover crops help to minimize soil erosion...because there is always something growing that holds the soil.
The main goal of cover cropping is to never leave the land bare. Experiment and explore what different cover crops, or combinations of cover crops, can do for your garden. Effective cover cropping benefits the soil and the crops that come after, saving time and money.