• E-mail
• Print
• Comment
• Font Size
• Digg
• del.icio.us
• Discuss article

Organic Means of Vegetable Gardening Good for You and the Soil

Posted on: Friday, 2 May 2008, 12:00 CDT

By Rick Nathanson Journal Staff Writer

A vegetable garden can be a nutritious addition to any yard, especially with organic practices that avoid chemical fertilizers and pesticides and animal manures that are high in salts and have traces of livestock antibiotics.

"A lot of people prefer the organic approach, and it's easier than trying to understand the proper use of chemicals," says Curtis Smith, a horticulture specialist with the New Mexico State University cooperative extension office in Albuquerque who writes a gardening column for the

Albuquerque Journal.

The health and viability of a vegetable garden start with the soil. There may be times when chemicals are appropriate, he says, such as with insect infestations or plant diseases that don't respond to organic solutions and can't be managed otherwise. In those cases, the home gardener should seek advice from plant experts before applying chemicals, or exercise the organic option of removing and trashing the problem plants and beginning again.

Some organic compounds may be useful. They include Neem, which comes in fungicide and insecticide formulas and is made from an evergreen tree that grows in India; Pyrethrum, an insecticide extracted from a plant related to the chrysanthemum; an entire class of insecticides grown from the soil bacteria Bacillus thurengiensis; and herbicides such as one made from 21 percent acetic acid vinegar and another made from corn starch.

Among the plants that should be high on an organic gardener's list are legumes -- the large bean family that includes fava, pinto, lima, garbanzo, green, black and navy beans. Legumes are important, Smith says, "because they improve the soil by fixing nitrogen gas from the air and converting it into a form that can be used by plants."

That supplements nitrogen that may exist in the soil. Nitrogen is an essential plant nutrient and part of the proteins that build cell material and plant tissue. It is necessary for the production of chlorophyll, without which photosynthesis can't occur, and it is an important determinant of plant growth and crop yields.

Nitrogen exchange

Legumes, says Smith, work in conjunction with a soil bacterium called rhizobium, which gets into the plant roots and causes it to swell and form nodules. "Through photosynthesis the plant feeds the bacterium and in return the bacterium captures gaseous nitrogen from the air and feeds it back to the plant in a form it can use." The root nodules are where the exchange occurs.

If soil already has adequate amounts of nitrogen from fertilizers, the rhizobium won't fix nitrogen from the air because the plant has enough, Smith says. If the soil is poor and needs fertilization, legumes working with rhizobium "will enrich the soil by taking nitrogen from the air and incorporating it into the plant in the form of proteins and amino acids and other organic compounds that are basically food to the plant, and to us when we eat the plant."

Soil can be enriched further by composting the spent legume plants and tilling the decomposed organic matter into the soil, providing many organic compounds.

Another way to enhance organic fertilization is to plant clover in the late summer around the garden perimeter, in rows, or as an underplant beneath the vegetables. After the vegetables in the garden have been harvested in the fall, the clover, also part of the legume family, can be dug into the soil. Do it while the clover is green because it loses its nitrogen as it turns brown, Smith says. As the green clover decomposes, the nitrogen becomes a nitrate, which can be absorbed and used by other plants in the spring.

Improvements

The spent plants from harvested vegetables can be composted to be a soil amendment in the spring. Other materials to compost include vegetable and fruit rinds, seeds, leafy vegetables such as lettuce and kale and kitchen waste. Meat or bread shouldn't be added to compost. Weeds pulled in the garden before they go to seed also can be composted and returned to the soil.

Amending the soil in this way can supplement or replace the use of animal manures and chemical fertilizers, Smith says. Only disease- free garden plant material should be composted and dug into the soil, otherwise the disease organism can be reintroduced.

Because not all plants are susceptible to the same diseases, rotating the plants yearly or changing their position within the vegetable garden will decrease disease organisms by eliminating their hosts, Smith says.

In addition to legumes, other plants that do well in a New Mexico vegetable garden include melons, squash, pumpkin, lettuce, kale, carrot, celery, broccoli, cauliflower, onion, chive, garlic, tomato and chile, says Smith. Among commonly planted herbs are annuals such as basil, cilantro, anise and fennel, and perennials like oregano, sage, mint, rosemary, thyme and lavender.

Source: Albuquerque Journal

More News in this Category