Grow Cover Crops for the Best Garden Soil

Enlarge Image Image Gallery Chickens, ducks and geese all make excellent cover crop processors. PHOTO: BONNIE LONG

Consider cover crops your most important crops, because the requirements for abundant food crops — building soil fertility, improving soil texture, suppressing weeds, and inhibiting disease and crop-damaging insects — can be best met by the abundant use of cover crops, season after season.

5 Benefits of Cover Crops

Soil Fertility. A vast array of soil organisms decompose once-living plants into nutrients easily taken up by plant roots, and add to your soil’s humus content (the final residues of organic matter in your soil, which assist nutrient uptake, improve texture and hold moisture). I grow organic matter in place using cover crops because, in many ways, a living cover crop is even better than adding manure and compost for fertility.

The area of most intense biological activity — ultimately the definition of soil fertility — is the rhizosphere, the zone immediately around plant roots. Plants release nutrients through their roots to feed their buddies in the soil — beneficial microbes and mycorrhizal fungi — that increase access to water and convert soil nutrients into forms more readily utilized by plants. If the intense bioactivity in the rhizosphere is the key to fertility, imagine the contribution of closely planted cover crops with vastly more root mass than more widely spaced food crops.

Soil Texture. Mycorrhizal fungi (beneficial fungi that grow in association with plant roots) produce glomalin, a substance which glues microscopic clay and organic matter particles into aggregate clumps, stabilizing the soil and making it nice and crumbly. This crumbly texture is more porous to oxygen and water. Bacteria encouraged by cover crops produce polysaccharides, which also act as soil glues.

Grass and grain cover crops with fine, dense root masses loosen soil texture as they decompose. Others, such as sweet clovers and sorghum-sudangrass hybrids, grow deep, aggressive taproots that break up soil compaction.

Erosion Prevention. A cover crop’s tight canopy protects the soil from the drying and scouring effects of wind and the forceful impact of heavy rain. The loosened soil structure achieved by cover cropping allows rapid absorption of rain and prevents runoff.

Soil Moisture. Organic matter added by cover crops acts like a sponge in the soil, absorbing rainwater and holding it for gradual release to plant roots. Thus, gardens that have been home to regular use of cover crops become more resistant to drought.

Protection From Weeds, Diseases and Insect Damage. Garden beds frequently planted with cover crops will have fewer problems with weeds. Cover crops suppress weeds, out-competing them for water and nutrients and shading them under a tight canopy, sometimes releasing chemical compounds that inhibit germination of weed seeds (a phenomenon called allelopathy). Plus, the roots of cover crops release nutrients that feed beneficial microbes in the soil. These microbes then suppress pathogens that cause root diseases. Some cover crop plants, such as rape, rye and sorghum-sudangrass hybrids, inhibit root-knot nematodes, which can be disastrous to beets, carrots and other root crops in some regions.