Cover crops have been used for years to organically enhance soils and add nutrients. The practice is said to be one of the more sustainable ways to produce crops worldwide.
A cover crops or green manures is when you grow plants specifically for the purpose of reducing soil erosion, increasing soil fertility and water retention while assisting in the management of weeds, pests and diseases. [1] [3] Depending on the species used as a cover crop they may provide a variety of the benefits we have just spoken about.
In order to get the maximum benefit from the practice cover crops are often tilled into the soil or mowed just before or after the crop has flowered. Common crops used are covered in Eliot Coleman book Four Season Harvest. In this book Mr. Coleman provides great information on common cover crops and how to use them. ***CHECK****
There has been a wealth of research done investigating cover crops. A great paper was published in the journal of Weed Management where researchers from Penn State University discussed and summarized the research that has been completed on cover crops. [2]
So now lets go through the results of the scientific investigation of the benefits of cover crops. I am going to investigate them in the following order:
Erosion
Weed management
Organic Material Addition
Beneficial Organisms
Nitrogen Fixation
Disease Management
***Impact on Soil Organisms (allopathic and beneficial)
Cost effectiveness and overall environmental impact
Erosion
Plants like cover crops have been shown in studies from all around the globe to reduce erosion. In order to use cover crops to reduce erosion generally they are planted where traditionally there would be open soil.
Their roots stabilize soils while the plant above ground helps dissipate the energy of rain water when falling and flowing over the surface. Slowing the water down helps the soil absorb more water while the stability prevents the water from carrying away the soil particles and nutrients.
Weed management
An added benefit of using cover crops to help prevent erosion is they grow where traditionally weed species may try to establish. The presence of these established cover crop plants helps prevent weeds by simply out competing them for the space to grow.
When cover crop living mulches were compared to herbicide practices a similar weed suppression performance was achieved. These results are significant as the weeds were less likely to adapt to a cover crop weed management strategy as they do to commercial herbicides.
Cover crops have been shown to reduce erosion and help keep weeds down. So what benefits do the plants themselves add?
For a full transcript including literature cited:
Green Manure Cover Crops Organic Sustainable Soil Fertilizers
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