http://www.motherearthnews.com/organic-gardening/cover-crops-improve-soil-zmaz09onzraw.aspx#axzz3KqFhHfgD
A cover crop is a crop planted primarily to manage soil erosion, soil fertility, soil quality, water, weeds, pests, diseases, biodiversity and wildlife in an agroecosystem (Lu et al.
2000), an ecological system managed and largely shaped by humans across
a range of intensities to produce food, feed, or fiber. Currently, not
many countries are known for using the cover crop method.
Cover crops are of interest in sustainable agriculture as many of them improve the sustainability of agroecosystem attributes and may also indirectly improve qualities of neighboring natural ecosystems. Farmers choose to grow and manage specific cover crop types based on their own needs and goals, influenced by the biological, environmental, social, cultural, and economic factors of the food system in which farmers operate (Snapp et al. 2005).
Rhizodeposition is a special advantage to working with cover crops. Many plants actually release sugars and other substances through their roots. They are like little solar engines, pumping energy down into the soil. With vigorous cover crop plants, this process goes on much more deeply than you would ever dig — 6 feet for oats and rye! If you are leaving your garden beds bare in winter, you are missing the chance to use cold-hardy crops such as cereal rye or oats to solar-charge your soil. Thanks to this release of sugars, the root tips of many plants host colonies of helpful microorganisms, and as the roots move deeper, the microbes follow.
But so much for scientific talk. If you’ve experimented with cover crops, perhaps you have dug up young fava beans or alfalfa seedlings to marvel at the nitrogen nodules on their roots. Pull up a marvelous mop of fibrous roots and shake out the soil. What crumb! The soil’s structure is nothing short of amazing! These are the moments an organic gardener lives for.
Cover crops are of interest in sustainable agriculture as many of them improve the sustainability of agroecosystem attributes and may also indirectly improve qualities of neighboring natural ecosystems. Farmers choose to grow and manage specific cover crop types based on their own needs and goals, influenced by the biological, environmental, social, cultural, and economic factors of the food system in which farmers operate (Snapp et al. 2005).
Legumes
Legume cover crops can fix nitrogen from the air, supplying
nitrogen to the succeeding crop as well as protecting the soil
from erosion and adding organic matter. The amount of nitrogen
fixed varies between species, although generally, more top growth
equals more nitrogen fixed. Some legume species have aggressive
tap roots which can break up subsoil compaction, but this requires
more than one year’s growth to happen.
How Cover Crops Help
Since the early 1900s, farmers have used cover crops to restore fertility to worn-out land. In addition to helping bulk up soil with organic matter, cover crops prevent erosion, suppress weeds, and create and cycle soilborne nutrients using the power of the sun.Rhizodeposition is a special advantage to working with cover crops. Many plants actually release sugars and other substances through their roots. They are like little solar engines, pumping energy down into the soil. With vigorous cover crop plants, this process goes on much more deeply than you would ever dig — 6 feet for oats and rye! If you are leaving your garden beds bare in winter, you are missing the chance to use cold-hardy crops such as cereal rye or oats to solar-charge your soil. Thanks to this release of sugars, the root tips of many plants host colonies of helpful microorganisms, and as the roots move deeper, the microbes follow.
But so much for scientific talk. If you’ve experimented with cover crops, perhaps you have dug up young fava beans or alfalfa seedlings to marvel at the nitrogen nodules on their roots. Pull up a marvelous mop of fibrous roots and shake out the soil. What crumb! The soil’s structure is nothing short of amazing! These are the moments an organic gardener lives for.
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