Living mulches
Sustainable Practices for Vegetable Production in the South
Dr. Mary Peet, NCSU
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Cover crops are usually killed or incorporated before establishing the vegetable crop. Recently, however, there has been interest in living mulch systems where the cover crop and vegetable grow together in the field for all or part of the growing season in order to extend weed control and other cover crop benefits such as decreased traffic compaction into the growing period of the crop.
Living mulches can compete for moisture and nutrients, so they are not recommended for low-growing, shallow-rooted, or drought-susceptible vegetable crops. Because they provide habitat for beneficial insects, living mulches sometimes decrease insect-pest populations. Population of other pests may increase however. In a New York study,use of a living mulch reduced population levels of cabbage looper, imported cabbage worm, aphid, and flea beetles, but slug populations increased.
Living mulches are not appropriate for all situations. It is very importatnt for characteristics of a living mulch to complement those of the vegetable crop. A cover crop should germinate and grow in the shade and be low growing relative to the main crop.
For example, a vining cover crop should be used only with tall vegetable crops (such as sweet corn). Bush type cover crops such as red clover should be used on shorter vegetables such as cabbage, peppers and determinate tomatoes. Cover crops should not be susceptible to the same diseases as the main crop , and should not interfere with harvest.
| Use of Living Mulches - Examples from Three States |
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| New York The advantages and disadvantages of living mulches are illustrated by a 4-year experiment with white clover grown with sweet corn. In the first year, corn yield was increased compared to rye mulch or herbicide treatment. By the fourth year, however, yields were lover in the clover plots. These yield decreases were associated with increases in weed biomass and decreases in clover biomass over time. |
| Pennsylvania, Lackawanna County Perennial and annual ryegrass have both been used as living mulches in vegetable production. When using perennial ryegrass, twenty pounds/acre of seed were broadcast after the vegetable crop was well established, but when half the soil between rows was still open. After the vegetable crop was harvested, the ryegrass was allowed to grow over the winter. Annual ryegrass was generally planted if the fields were to be used for vegetables the following year. Perennial ryegrass was only recommended if the field was to be put in hay or pasture the following year. Dwarf ryegrass, tall fescue, and bluegrass did equally well, but seed costs were higher for these grasses. |
| North Carolina, Buncombe County Steve White experimented with peppers intercropped with living mulches of both red clover and quailhaven soybeans. The soybeans and clover were established by broadcasting and raking in 4 to 5 weeks after setting out the pepper transplants. The soybeans have the potential to provide more biomass than the red clover, but White found the red clover to be more consistent in its biomass and nitrogen production. The soybeans must be planted early to maximize their contribution of nutrients. Soybeans also may not stand up well to foot traffic. |
 Living mulches may be planted before or after the vegetable crop. If the mulch is planted before the vegetable crop, strips of the mulch must be prepared for the crop by tilling, mowing, or applying herbicides. The vegetable crop may be planted in double or triple rowsbetween wider strips of living mulch to lessen competition between the crop and the mulch.
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To establish a living mulch:
No data are available on the economic aspects of living mulches in vegetable crops but an enterprise budget for blueberries is presented here.
Calculating nutrients available from a cover crop.
bridgesj@unity.ncsu.edu