This is one of the most powerful nitrogen-fixers of all legumes. A good stand can take 250 pounds of nitrogen per acre from the air each year. Alfalfa needs a deep soil without hardpan or an underlying rock layer, because it sends its roots down deep. Research ers have traced them for well over 100 feet, and 20 to 30 feet is average.
Alfalfa’s deep-rooting ability is the source of its great nutritional power, feeding as it does from mineral-rich subsoil that has not been worn out and depleted. Alfalfa is strong in iron and is also a good source of phosphorus, potassium, magnesium, and trace minerals.
You can easily sprout alfalfa seeds in the kitchen, and you may even want to grow some in your garden for highly nutritious alfalfa greens, or use its leaves for tea. Alfalfa used as a meal is a great compost stimulant and activator, particularly good for composting household garbage.
Alfalfa will make good growth wherever dandelions grow. Dandelions themselves are deep divers, their presence indicating that the subsoil is easy to penetrate. Alfalfa grown in pastures will give protective shelter for shallower-rooting grasses, keeping other plants alive longer during spells of dry weather. As a trap crop, alfalfa will draw lygus bugs away from cotton. Two percent alfalfa provides sufficient control, but it should be planted about a month before the cotton.
Buckwheat is valuable as a soil builder and it will grow on very poor soils while collecting lots of calcium. Used in this manner it will take the light away from low-growing weeds, choking them out. If plowed under as green manure, it will sweeten the soil and make it more suitable for growing other crops. Buckwheat does not like winter wheat.
Peas, beans, cabbages, and turnips revel in soil containing lime, but a few plants — notably those belonging to the Heath family, such as erica, azalea, and rhododendron — actually dislike it. Potatoes and a few cereals are not at their best if lime is applied to the ground immediately before they are planted or sown.
Land in need of lime does not respond to cultivation and manuring as it should, and often coarse weeds such as sheep sorrel flourish. Sometimes a green scum grows over the surface. A soil test that reveals excessive acidity indicates the need for liming.
Buckwheat accumulates calcium, and when composted or plowed under as green manure enriches the soil. Lupine (Lupinus) has roots that penetrate to surprising depths even on steep, gravelly banks or exposed sunny hills. It adds calcium to the soil, too, and is of value to grow on poor, sandy soils worthless for other purposes.
Scotch broom, a member of the Legume family, also accumulates calcium but may become a weed unless kept in check. Melon leaves are rich in calcium and should be added to the compost heap when the plants are spent.
Planting clover between rows of grapes will add nitrogen to the soil. This also works well in orchards or with companion grasses. Clover dislikes henbane and also members of the Buttercup family, which secrete a substance in their roots that inhibits the growth of nitrogen bacteria and poisons the soil for clover. This poisoning is so effective that clover will disappear in a field if buttercups are increasing. Clover has a stimulating effect on the growth of black nightshade (Solanum nigrum).
Compost is largely composed of decayed organic matter that has heated sufficiently to kill weed seeds and then has thoroughly decomposed. Plant preparations may be used to influence or speed up the fermentation process, and these — even when added in small amounts — can influence the entire operation. Once conditions are right, earthworms enter the compost pile and assist the other microorganisms in the breaking-down process.
Certain plants such as stinging nettle may be used to speed up or assist fermentation in the compost heap or manure pile. This plant is an excellent soil builder and, like comfrey, has a carbon-nitrogen ratio similar to barnyard manure. Nettles also contain iron.
Several other herbs are particularly well endowed with minerals and can be of value when incorporated into compost. These include dandelion, which absorbs between two and three times as much iron from the soil as other weeds; salad burnet, with its rich magnesium content; sheep sorrel, which takes up phosphorus; and chicory, goosegrass, and bulbous buttercup, which accumulate potassium. Horsetail shares honors with ribwort and bush vetch for a capacity to store cobalt. Thistles contain copper as a trace element.
Compost is the best fertilizer for herbs as well as garden vegetables and is particularly rich if weeds are put in the pile instead of being destroyed. Use all herb refuse obtained in the garden, too, and naturally all the kitchen waste, particularly in a household where cooking with herbs is a frequent feature.
Any organic material can be added, but refuse of a woody nature will decompose more rapidly if it is crushed or chopped first and used as a base mixed with materials such as grass clippings. Leaves picked up in the fall make good compost, but since they are apt to pack, they should be mixed with other material. Bulky materials form a solid mass of rotting vegetation, lack oxygen, and quickly become sour and greasy.
When making a pile, the site first should be well dug to allow for a quick entry of earthworms. Incorporate sods into the heap. Build your pile up to a height of about six feet with straight sides and a slightly concave top. The contents must be kept moist and allowed to heat so that weed seeds are killed. The quicker the heating, the earlier the heap should be turned and restacked.
Turpentine substance, washing from the leaves of conifers, will retard fermentation. Birch trees in the vicinity assist fermentation, even if their roots penetrate the heap. It is best, however, to have them at least six feet away.
We are all familiar with the ability of legumes to draw nitrogen from the air and “fix” it to their roots. Actually, there are many plants that get only about 5 percent of their nourishment directly from the soil.
Have you ever noticed how plants, particularly grass, look greener after a thunderstorm? This is not an optical illusion. They really are greener as a result of the electrically charged air, which frees its 78 percent nitrogen content in a water-soluble form.
Rain and lightning are fertilizing agents. Each time lightning strikes the earth, large amounts of nitrogen are charged into the ground. One authority states that 250,000 tons of natural nitrogen are produced every day in the 1,800 thunderstorms taking place somewhere on the earth. In some places this may amount to more than 100 pounds per acre per year. Rain also brings nitrogen — in some areas as much as 20 pounds per acre annually.
Sulfur comes down with the rain, possibly producing as much as 40 pounds per acre per year. Rainwater also contains carbonic acid, forming carbon dioxide in the soil where it is needed for the plant-feeding process. Millions of tons fall yearly, and when we consider that nearly half the makeup of a plant is carbon we realize how important this is. Evidence also seems to show that rare minerals such as selenium and molybdenum are washed down in rain.
Snow, which furnishes not only nitrogen but also phosphorus and other minerals, yields an extra bonus denied warm-climate areas. Snow contains 40 percent less heavy water, or deuterium oxide, than normal water. Deuterium is a heavy isotope, a form of hydrogen but a little different. Combined with water it does not form H2O, the water molecule, but D2O instead. Heavy water, according to the Russian scientists who observed this, slows down some chemical and biological processes of growing plants. When the heavy-water molecules are removed, plants seem to grow faster. Thus crops are aided in short-season, snowy climates such as that of Alaska. Even fog contributes to the soil’s fertility, especially along the seacoast, where it brings in large quantities of iodine, nitrogen, and chlorine.
Dust, though sometimes disagreeable, has its good points too, containing minerals, organic matter, and beneficial organisms often in substantial quantities essential to plant growth. Dust may be carried for thousands of miles, even being held suspended for long periods in the upper atmosphere to be washed down eventually by rain. Many believe that dust is one of the most significant factors in restoring minerals to the exhausted soil and that it also contains bacteria important to healthy soil life.
Here’s a way you can obtain some of the benefits of electroculture without waiting for a thunderstorm. Tie your tomato plants to metal poles or trellises (ours are concrete-reinforcing wire bent in an inverted V-shape, with a row of tomato plants on each side), using nylon strips cut from discarded panty hose. These sturdy supports also attract static electricity. A friend who tried this reported that she harvested an abundant crop of extremely large tomatoes, and her plants continued producing right up to frost.
Green manures are cover crops, usually achieved by planting lowpriced seed. If fall-planted, the cover protects the soil surfaces of fields or garden plots from erosion from winter winds, snowstorms, and quick thaws. It acts as an insulating blanket, keeping the soil warmer in winter and cooler in summer. This encourages soil life activity in general and earthworms in particular. The more earthworms in the soil, the more channels they’ll burrow deep in the subsoil, bringing to the surface useful minerals and nutrients that will increase the health and insect-resistance of food plants.
Yellow sweet clover
Red clover
Alsike clover
White clover
The clovers make fine green manure crops. Clover’s growth is limited by Henbane and Buttercup family members.
The roots of many green manure crops themselves reach deeply into the subsoil, where they absorb and bring up valuable nutrients. These revitalize the soil when the plants are plowed under to decompose.
Certain green manure crops, the legumes, have the ability to capture and fix large amounts of nitrogen from the air, also adding this important nutrient to the soil. Alfalfa is one of the best of these, and it is also high in terms of protein, which breaks down into usable nitrate fertilizer.
Other useful green manure cover crops are barley, bromegrass, buckwheat, cheat grass, alsike clover, cowpeas, lespedeza, millet, rape, spring rye, Italian ryegrass, winter rye, sorghum, soybeans, Sudan grass, sunflowers, common clovers, hairy vetch, and winter wheat.
For the home garden, kale makes a good, thick, nonleguminous green manure cover crop for the winter months. It is an easily grown, tasty food with a flavor that is improved by frost, and you can actually dig it out from under the snow in the dead of winter. When the kale starts growing again in the spring, it can be tilled under to add green manure to the soil for the spring garden.
Sold under various names such as Legume Aid (Burpee) and Nitragen (Farmer), these preparations are aids to peas, beans, soybeans, sweet peas, etc., for better blooms and increased yields. Treating legume seeds with the proper inoculants helps them to develop root nodules, which convert free nitrogen into plant food.
Though nitrogen makes up 80 percent of the volume of the atmosphere, it is almost useless to most plants, for it must be changed into a compound before it can be used. Lightning combines or fixes small amounts of this nitrogen and oxygen in the air, thus forming oxides of nitrogen that are washed out of the atmosphere by rain or snow to reach the soil. (See Fertilizers, Nature’s Own in this chapter.)
Nitrogen-fixing bacteria living in nodules on the roots of legumes — alfalfa, beans, clover, esparsette, kudzu, lespedeza, peas, peanuts, soybeans, winter (hairy) vetch, and others — can change atmospheric nitrogen into nitrogen compounds useful to themselves and other plants. Farmers for centuries have rotated their crops to take advantage of this increased soil fertility produced by legumes.
Clover is particularly beneficial if used as a green manure crop and plowed under before planting a crop of wheat or corn the following season. The decaying legume, rich in fixed nitrogen, increases the nitrogen content of the soil without the need for commercial fertilizers. A green manure crop of alfalfa will benefit a crop of cotton. Red clover may be used on soils too acid and too poorly aerated for alfalfa. The optimum pH for red clover is between 5.8 and 6.8 but it can stand a pH below 6.0 and still do reasonably well.
The steps in the nitrogen cycle can be traced in the growth and use of clover:
1. Atmospheric nitrogen is changed into proteins by the action of nitrogen-fixing bacteria growing in nodules on the clover roots.
2. After plowing under, the clover proteins are changed into ammonia by ammonifying bacteria.
3. Ammonia is then changed into nitrates by nitrifying bacteria.
4. Both ammonia and nitrates are used by other plants to form plant proteins.
The nitrogen-fixing bacteria of legumes benefit not only themselves but also other plants nearby. Peas and beans, for instance, benefit potatoes, carrots, cucumbers, cauliflower, cabbage, summer savory, turnips, radishes, corn, and most other herbs and vegetables.
Peanuts, another legume, can be used as a second crop after an earlier one is out, provided that you have a long growing season.
On larger acreages, lespedeza, kudzu, and esparsette may be used to aerate the soil and put nitrogen into it, while winter vetch and soybeans make excellent cover crops. Legumes sown with a small amount of mustard are helpful to grapevines and fruit trees. Peanuts are excellent to grow in an orchard of newly set nut trees.
See Legumes, above.
See the chapter on Grasses, Grains, and Field Crops.
Certain weeds indicate a soil rich in potassium. These are marsh mallow, knapweed, wormwood, opium poppy, fumitory, Russian thistle, tansy, and sunflower. Red clover, however, is a good indicator of potassium deficiency.
Tobacco takes up potassium in its leaves and stalks and is thus a good plant on the compost pile if it has not been sprayed with chemicals. Vegetables that like potassium are celeriac and leek.
These are the bacteria that live in nodules on leguminous plants and turn atmospheric nitrogen into a useful form for building plant proteins. Unfortunately, they withhold their talents from such useful plants as corn and wheat. (See Legumes in this chapter.)
Soapberry or chinaberry is the name of a group or genus of trees and shrubs that bear fruit containing a soapy substance called saponin. Bouncing Bet is probably our best-known saponin-rich plant. Other unrelated plants such as primroses and carnations also have this quality, as well as many legumes, cyclamen tubers, camellia, viola, mints, horse chestnut, orach, pokeweed, runner beans, tomatoes, mullein, potatoes, and spinach. These plants are important because their decomposing remains create a favorable environment for the plants that come after them.
Commercial saponin is used as a foam producer in beverages and fire extinguishers and also as a detergent useful in washing delicate fabrics.
Kelp, a type of brown alga, provides fertilizer and is a source of the chemical element iodine, particularly the giant kelp of the Pacific. Chemists also extract from kelp large amounts of algin, which is useful in such commercial products as ice cream and salad dressings by virtue of its ability to hold several different liquids together.
Kelp is about 20 to 25 percent potassium chloride, and it also contains common salt, sodium carbonate, boron, iodine, and other trace elements. For gardeners who live on or near the seacoast, seaweeds are a natural and usually wasted resource that can be utilized for mulching and in compost piles. They are especially good materials to put around fruit trees. Another advantage is that decomposing seaweed is less attractive to mice than is straw.
Chopping seaweed may be advantageous if only for cosmetic reasons. It may be also advisable to rinse off the salt, but it is not necessary to be too fussy about this. The small amount left clinging will do no harm. Eelgrass, which dries into a light “hay” and doesn’t pack down, is a perfect nonsmothering material for many plants. (See Eelgrass in the Wild Plants chapter.)
Another use for “sea power” to promote fertility is liquefied seaweed, which may be applied as a foliar fertilizer directly to the leaves of plants. It is particularly helpful to trees.
It has been found that seaweed as a fertilizer helps to promote frost resistance in tomatoes and citrus fruits, as well as increasing the sweetness of some fruits and giving better resistance to pests and diseases. Beets and parsnips respond badly to boron shortages in the soil, so chopped kelp makes an excellent mulch for them.
Seaweed helps to break down certain insoluble elements in the soil, making them available to plants. This quickens seed germination and further aids development of blossoms and fruits, resulting in increased yields.
For those who cannot readily obtain seaweed, there are seaweed preparations and fish emulsion, available at most garden centers and through gardening catalogs.
Eelgrass makes an enriching mulch and is fine for composting.
Another idea for gardeners who, like myself, live far inland is to use water plants. Though not as rich in nutrients as seaweed, they make good mulch if chopped, and are good additions to the compost. Water hyacinth, a plant of tropical America, has escaped into the wild and has become a pest, choking many small streams. Dredged from waterways, it is valuable on the mulch pile. Here where I live, water lilies grow profusely in shallow pools and are easily obtainable. My husband, Carl, and I usually brought back a tubful of water weeds of some kind every time we went fishing.
This is not a true clover although it is a legume. White and yellow sweet clovers live for two years, and their large roots penetrate deeply into the soil. At the end of the second season, they decay to enrich the soil with nitrogen and decomposing vegetable material.
Sour clover, a kind of sweet clover used almost entirely to improve the soil, is often called melilot.
Spoiled sweet clover hay or poorly preserved silage never should be fed to animals. The hay contains coumarin, an anticoagulant, which develops toxicity as the clover decomposes and may cause both internal and external bleeding.
Many weeds seem to have a mysterious capacity for enriching soils. Jimsonweed (datura) grown near pumpkins will promote their health and vigor; the best watermelons come from the weediest part of the patch; onions grown with weeds (but not allowed to be overwhelmed) are apt to be larger than those in clean-cultivated rows.
This is particularly true if the weeds are the so-called “deep divers” that break up the subsoil, allowing the roots of the vegetable plants to have a larger-than-usual feeding zone. Deep divers sometimes bring up from below the hardpan mineral elements that the roots of food plants cannot reach. The high mineral content of weeds is another reason for adding them to the compost pile. (See Compost in this chapter.)