Garden Soils For Herbs

There is something deeply satisfying in improving the soil. There is certainly plenty of reason for this - the soil is one of our most precious resources. Because herbs are so varied in their soil preferences, it isn't possible to give guidelines on how to build a soil that's good for all herbs.

A good soil has excellent texture, structure, and porosity. A healthy soil smells wonderful, is spongy and crumbly, well textured and aerated. It is also full of beneficial soil life, and by its health it deters noxious soil organisms from inhabiting it, much as a healthy human body repels disease germs naturally. A healthy soil contains not only hearty populations of earthworms, but also such tiny creatures as bacteria, and such growths as actinomycetes, algae, fungi, and protozoa, whose complex interrelationships with each other and the soil itself make it clear that the living soil is a world in itself. All of these organisms have a part in decomposing organic material in the earth, and so enriching it.

Sandy soils and clay soils are less than good; they represent an imbalance of the ideal soil ecology. Few gardeners are presented with good soil when they first begin gardening on a piece of land. They have to work with the qualities of either sandy or clay soil and improve them. Clay soils contain a tremendous variety and amount of mineral nutrients, in most cases. But it is difficult for plants to utilize the nutrients in a clay soil, because the soil structure is so dense.

There are many techniques for lightening clay soil organically. One, recommended by gardening experts entails plowing rice hulls into the clay, working them down to a depth of 3 feet. Some recommend using enough rice hulls so that the soil resembles rice hulls with clay bits adhering to them. Then they suggest continued additions of organic amendments, until the soil is one-half organic material and one-half the original amended clay. Decomposition can be hastened by spraying the amended soil with a tea made from manure and stinging nettles, soaked in pure water for a week or more, and diluted to a pale color. Commercially prepared bacterial cultures can also be used. The following year, the land is tilled again, and a leguminous cover crop planted to enrich the soil by fixing nitrogen, and if it is a deep-rooted crop, by bringing nutrients up from the subsoil with its long roots.

Sandy soil actually lacks nutrients, unlike clay soil, which has nutrients in a structure too compacted to allow absorption by plants. There is only one way to enrich sandy soil, and that is by continually adding organic materials such as kitchen wastes, manure, leaves, and green manure to it. These materials will work wonders within two or three years' time. Although it is a lot of work, any committed gardener will agree that the result is well worth it when one day he gathers a handful of soil, which once was only sand, and finds it is now spongy, sweet-smelling, and alive with goodness.

Cultivation

There are as many notions of how to cultivate the soil as there are systems of gardening. Many gardeners use farm machinery to cultivate, but biodynamic gardeners think machinery is too heavy and compacting on the soil and prefer to till by hand to keep the soil well aerated.

The biodynamic gardener will set to work "double-digging" the soil of his garden, carefully separating the topsoil from the subsoil while he does so. Double-digging is not really such a new idea. The ancient Greeks noted 2,000 years ago that plants flourished in the earth moved by landslides; the soil there was well aerated, loose, able to absorb warmth, moisture, and nutrients easily.

In the biodynamic approach to cultivation, breath ability is important. Double-digging aims to cultivate deep (two spades deep, or about 24 inches is considered good), breaking hardpan layers and allowing the movement of subterranean moisture and gases upward, and the movement of moisture and gases from the air downward.

Testing your soil for nutrients and pH

Testing your soil for nitrogen, potash, and phosphorus, and to find out its pH level can save a lot of time and money.

If you learn that your soil's pH is too high, you can add a layer of decomposed pine needles, oak leaf mold, or acid peat moss. To raise the pH level, add dolomitic lime to the soil. Well-made compost is the most balanced substance you can add to the soil: a thoroughly aged compost helps to correct both acid and alkaline conditions naturally. When sufficient organic materials are added to the soil, plants tend to tolerate a wider range of acidic or alkaline conditions in the soil and still remain very healthy.

Trace elements and soil deficiencies

Trace elements are naturally present in humus, and they are essential to a healthy soil. Many soils today are precariously out of balance due to overuse of chemical fertilizers and other improper farming procedures. And some soils are naturally low in certain trace elements. So it is good "health insurance" to make sure your garden soil is rich in these vital substances.

Techniques used commonly by organic gardeners, such as composting, mulching, and applying soil amendments like seaweed and fish fertilizers, all help to maintain the presence of trace elements in the soil. There are also specific plants that act as accumulators of trace elements. When these "weeds" are intetercropped, composted, or used as green manure, they are especially useful in regenerating the soil. Stinging nettle, for instance, accumulates sulfur, potassium, calcium, and iron. Chamomile concentrates calcium, sulfur, and potash in its tissues. Dandelion concentrates potash and zinc. Valerian increases phosphorus in its vicinity. In China, plants like these are placed directly on the soil for crop fertilization.

Composting

Any discussion of soil regeneration would be incomplete without a mention of compost. Compost is garbage heading toward a rebirth as humus. Grass cuttings, weeds, garden residues, such as vines and stalks, hay, leaves, sawdust, kitchen scraps (but not meat or bones), sewage sludge, manure, nutshells, and other organic wastes, such as leather dust, coffee wastes, vegetable pulp from a juice company, or brewery wastes, are all excellent candidates for the compost pile.

There are two basic types of composting: anaerobic (without air) and aerobic (with air). Aerobic composting is faster and is more commonly used. The three methods here are all aerobic methods.

The indore compost method Sir Albert Howard, whose agricultural research in Indore, India, served as a foundation for the organic gardening movement, developed a composting method that is regarded as the most classical aerobic technique. It is known as the Indore method. The compost can be made in either open piles or bins. Piles are usually made so that they measure 6 feet wide, 10 to 30 feet long, and 3 to 5 feet high. A 6-inch layer of plant wastes is set down as a foundation for the pile, covering the entire area over which the pile will be built. This layer can include leaves, sawdust, spoiled hay or straw, wood chips, or garden residue. After that, 2 inches of manure and animal bedding are added to the pile. A layer of topsoil about 1/8 inch thick follows next. Then lime, phosphate rock, granite dust, or wood ashes can be spread over the earth layer. The pile is watered, and layers are repeated in the order given until the pile is 3 to 5 feet high. It is important that the pile retain its aerating qualities. To provide ventilation, several pieces of wire netting formed into tubes are vertically in the center of the heap, about 3 1/2 feet apart.

Within several days, the pile will heat up and begin to decay. It can be turned with a pitchfork in two or three weeks, and again about five weeks after being made. The compost will be ready to use in three months.

Compost in 14 days You can also make a compost that will be decayed enough to be applied to the garden about 12 to 14 days after the pile is begun. All the organic material must be well shredded in order for this method to work. The shredded materials are mixed together and stacked into a pile about 5 feet high, but no higher. The heap should be turned every two to three days, until the compost is finished.

Biodynamic compost The biodynamic compost preparations are made from six herbs: yarrow blossoms, chamomile blossoms, stinging nettle, oak bark, dandelion flowers, and valerian flowers. These preparations are inserted into the compost pile in order to help ripen the compost and increase its ability to hold nutrients. A teaspoonful of the appropriate preparation is inserted into a 20-inch-deep hole, slanting downward in the compost pile. The holes should be made halfway up the compost heap. The stinging nettle preparation requires 4 to 5 teaspoonfuls, but each of the others requires a level teaspoon, not heaping. Then the holes are filled in and closed with organic matter.

Biodynamic gardeners like to locate their compost piles near an oak tree, because the oak provides a beneficial environment under its branches and allows the creation of good soil in its vicinity. Piles are located at least 6 feet from the tree trunk, to avoid creating the potential for disease in the tree.

Nitrogen fixing

Of the three main elements needed for the soil's health, nitrogen has the most dramatic effect on plant growth. Plants cannot directly absorb the nitrogen mixed with oxygen in the air. Instead, they depend upon nitrogen fixing bacteria in the soil to make it available to them.

The tremendous power of lightning flashes has the capacity to fix nitrogen in the soil, and some scientists theorize that it was this contact between lightning and soil that actually allowed the first life to develop on planet Earth. The reliable underground action of nitrogen-fixing bacteria is a much more common way to enrich a nitrogen-poor soil, however. Nitrogen-fixing bacteria flourish on the roots of over 1,350 species of leguminous plants, such as clover, alfalfa, vetch, peas, and beans. Some trees are also nitrogen fixing, such as acacia, red alder, and autumn olive. There are also nitrogen-fixing shrubs, which can be planted in hedges around gardens and orchards to increase soil fertility.

Cover crops such as clover and alfalfa are often cut and turned into the soil before they have flowered, releasing abundant nitrogen in a matter of weeks. This practice of green manuring is an ancient one and has been employed in many cultures. Sometimes, rather than turning the nitrogen-rich plants into the soil, gardeners make a mulch of them. Sometimes they add the cut legumes to the compost pile. Whichever way the plant is handled, the eventual result is the same: more nitrogen in the soil.

Some legumes can be sown in the late summer, and they will grow through winters where the temperature does not go below freezing. They include winter vetch, rough pea, fenugreek, sour clover, crimson clover, bur clover, and Austrian winter pea. There are many more legumes which flourish in the summer. Alfalfa is one of the most common. Some others are crotalaria, which can be used in poor sandy soils, in southern climates; red clover, good for cool temperate climates; lespedeza, used in southern climates a good deal; and cowpea and sweet clover, which grow almost anywhere.

Mulching

Spreading mulch over garden soil retains moisture, keeps down weeds, protects plants from too much heat in summer and too much cold in winter, and fertilizes the soil. Some gardeners have made mulching into a real art. If a soil has been depleted, most gardeners feel that it must be built up by digging in compost before beginning the no-digging mulch system.

Practically any organic material-straw, shredded leaves mixed with straw, sawdust mixed with soybean meal, grass clippings, cornstalks, cocoa hulls, rice hulls, buckwheat hulls, cut up corncobs, alfalfa hay; and pine needles are some of the most used mulches. Mulch can be used to good advantage in the vegetable, herb, and flower garden, in fields, and in orchards. Many gardeners grow cover crops such as soybeans, millet, buckwheat, rye, vetch, clover, and alfalfa and cut them for use as mulch. Some gardeners also add a thin layer of seaweed or kelp to their mulch, as it is rich in minerals.

In fact, one thing to consider is the nutrient quality of the mulching material. Straw, corncobs, and sawdust are low in nitrogen and benefit from being mixed with leguminous mulch. Pine needles are acid, as are oak leaves, and do not make a good mulch for plants that need a neutral or alkaline soil. Strawberries like them, though, as do azaleas, rhododendrons, bearberry, and trailing arbutus.

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