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Organic Gardening Requires Some Knowledge of Soils

Posted on: Wednesday, 30 April 2008, 12:00 CDT

Organic gardeners want to grow plants in the most natural way possible without using chemicals, inorganic fertilizers, and artificial pesticides.

They compost organic matter, use mulches, and recycle organic waste to keep their soil fertile.

Successful organic gardeners begin with a knowledge of established gardening practices based on horticultural principles. Here are some basic tips on growing a summer vegetable garden (most also apply to flower gardens):

* Choose a good location in full sunlight. Most plants need at least 6-8 hours of sunshine to thrive.

* Plan the garden layout on paper so the crops have enough room and don't shade each other.

* Grow varieties adapted to our area.

* Use good seed, plants, and supplies.

* Plant seeds and transplants properly.

* Use mulches whenever possible.

* Water properly.

* Harvest crops at the proper time.

* Control weeds, insects and diseases.

Besides these principles, certain practices need to be stressed when you try to grow vegetables organically.

Start by looking for plants with a built-in resistance to disease. One good way to get superior plants with desirable characteristics is to grow hybrids, which are uniform and usually stronger, healthier, and more productive than open-pollinated varieties.

You also need to build a healthy soil. The success of a garden depends largely on the fertility of the soil. A loose, well-drained and well-aerated soil enables roots to grow well and lowers the occurrence of seedling blights and diseases.

Clay or poorly drained soils can be improved by planting green manure crops or by adding compost, straw, hay, leaves, grass clippings or other organic soil conditioners. Adding organic matter to almost any of our local soils each year is a good idea.

Vegetables grow best in a soil with a pH of 6.0 to 6.5. Essential mineral elements won't be available to plants in soil with a pH much below 6.0 or higher than 7.0. An exception is Irish potatoes, which like a 5.0 to 5.5 pH to help prevent scab disease.

Gardeners commonly add lime to the soil every year or two, but unneeded lime can create problems that are hard to correct. A soil test can tell you how much lime and other elements your soil needs.

Plants need 16 elements to grow. Of these, nitrogen, phosphorus and potassium are the most important. Carbon, hydrogen, and oxygen are provided by air and water and seldom limit growth. Calcium and magnesium are supplied by liming. Plants get sulfur from decomposing organic matter and rainwater.

The other elements are referred to as micronutrients because they are required in such small amounts. They include iron, copper, boron, chlorine, manganese, molybdenum and zinc. Sandy soil can be deficient in micronutrients.

Natural sources of nutrients are manure, dried blood, fish meal, cottonseed meal, rock phosphate, muriate of potash, and wood ashes.

Animal manure is still the most popular organic material used in gardens, not only for fertility but also for increasing the amount of organic matter in the soil. Cricket manure has been popular in the Augusta area for many years.

Although the amount of nitrogen in manure varies according to its source, most fresh manure from cattle or horses contains only about 0.5 percent nitrogen, about 1/20th of the nitrogen found in an equal amount of 10-10-10 fertilizer. That means about 20 times more manure would be needed to get the same amount found in the 10-10-10 fertilizer.

For the safest use of animal manures (to guard against potential E. coli infection) apply fresh manure at least 120 days before harvesting any vegetable that will be eaten without cooking. If you apply it within 60 days of harvest, use only aged or fully composted manure (1 year or oder). There is no E. coli danger from cricket manure since it comes from an insect and not an animal.

Source: Augusta Chronicle, The

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