ORGANIC GARDENER'S COMPOSTING TEXT

matter or add plant nutrients that cause more vegetation to be grown there. In one study, simply returning the manure resulting from hay taken off a pasture increased earthworms by one-third. Adding lime and superphosphate to that manure made an additional improvement of another 33 percent. Every time compost is added to a garden, the soil's ability to support earthworms increases. Some overly enthusiastic worm fanciers believe it is useful to import large numbers of earthworms. I do not agree. These same self-interested individuals tend to breed and sell worms. If the variety being offered is _Eisenia foetida,_ the brandling, red wiggler, or manure worm used in vermicomposting, adding them to soil is a complete waste of money. This species does not survive well in ordinary soil and can breed in large numbers only in decomposing manure or other proteinaceous organic waste with a low C/N. All worm species breed prolifically. If there are _any_ desirable worms present in soil, their population will soon match the available food supply and soil conditions. The way to increase worm populations is to increase organic matter, up mineral fertility, and eliminate acidity. Earthworms and their beneficial activities are easily overlooked and left out of our contemplations on proper gardening technique. But understanding their breeding cycle allows gardeners to easily assist the worms efforts to multiply. In temperate climates, young earthworms hatch out in the fall when soil is cooling and moisture levels are high. As long as the soil is not too cold they feed actively and grow. By early spring these young worms are busily laying eggs. With summer's heat the soil warms and dries out. Even if the gardener irrigates, earthworms naturally become less active. They still lay a few eggs but many mature worms die. During high summer the few earthworms found will be small and young. Unhatched eggs are plentiful but not readily noticed by casual inspection so gardeners may mistakenly think they have few worms and may worry about how to increase their populations. With autumn the population cycle begins anew. Soil management can greatly alter worm populations. But, how the field is handled during summer has only a slight effect. Spring and summer tillage does kill a few worms but does not damage eggs. By mulching, the soil can be kept cooler and more favorable to worm activities during summer while surface layers are kept moister. Irrigation helps similarly. Doing these things will allow a gardener the dubious satisfaction of seeing a few more worms during the main gardening season. However, soil is supposed to become inhospitably hot and dry during summer (worm's eye view) and there's not much point in struggling to maintain large earthworm populations during that part of the year. Unfortunately, summer is when gardeners pay the closest attention to the soil. Worms maintain their year-round population by overwintering and then laying eggs that hatch late in the growing season. The most harm to worm multiplication happens by exposing bare soil during winter. Worm activity should be at a peak during cool weather. Though worms inadvertently pass a lot of soil through their bodies as they tunnel, soil is not their food. Garden worms and nightcrawlers intentionally rise to the surface to feed. They consume decaying vegetation lying on the surface. Without this food supply they die off. And in northern winters worms must be protected from suddenly experiencing freezing temperatures while they "harden off" and adapt themselves to surviving in almost frozen soil. Under sod or where protected by insulating mulch or a layer of organic debris, soil temperature drops gradually as winter comes on. But the first day or two of cold winter weather may freeze bare soil solid and kill off an entire field full of worms before they've had a chance to adapt. Almost any kind of ground cover will enhance winter survival. A layer of compost, manure, straw, or a well-grown cover crop of ryegrass, even a thin mulch of grass clippings or weeds can serve as the food source worms need. Dr. Hopp says that soil tilth can be improved a great deal merely by assisting worms over a single winter. Gardeners can effectively support the common earthworm without making great alterations in the way we handle our soil. From a worm's viewpoint, perhaps the best way to recycle autumn leaves is to till them in very _shallowly_ over the garden so they serve as insulation yet are mixed with enough soil so that decomposition is accelerated. Perhaps a thorough garden clean-up is best postponed until spring, leaving a significant amount of decaying vegetation on top of the soil. (Of course, you'll want to remove and compost any diseased plant material or species that may harbor overwintering pests.) The best time to apply compost to tilled soil may also be during the autumn and the very best way is as a dressing atop a leaf mulch because the compost will also accelerate leaf decomposition. This is called "sheet composting" and will be discussed in detail shortly. Certain pesticides approved for general use can severely damage earthworms. Carbaryl (Sevin), one of the most commonly used home garden chemical pesticides, is deadly to earthworms even at low levels. Malathion is moderately toxic to worms. Diazinon has not been shown to be at all harmful to earthworms when used at normal rates. Just because a pesticide is derived from a natural source and is approved for use on crops labeled "organically grown" is no guarantee that it is not poisonous to mammals or highly toxic to earthworms. For example, rotenone, an insecticide derived from a tropical root called derris, is as poisonous to humans as organophosphate chemical pesticides. Even in very dilute amounts, rotenone is highly toxic to fish and other aquatic life. Great care must be taken to prevent it from getting into waterways. In the tropics, people traditionally harvest great quantities of fish by tossing a handful of powdered derris (a root containing rotenone) into the water, waiting a few minutes, and then scooping up stunned, dead, and dying fish by the ton. Rotenone is also deadly to earthworms. However, rotenone rarely kills worms because it is so rapidly biodegradable. Sprayed on plants to control beetles and other plant predators, its powerful effect lasts only a day or so before sun and moisture break it down to harmless substances. But once I dusted an entire raised bed of beetle-threatened bush bean seedlings with powdered rotenone late in the afternoon. The spotted beetles making hash of their leaves were immediately killed. Unexpectedly, it rained rather hard that evening and still-active rotenone was washed off the leaves and deeply into the soil. The next morning the surface of the bed was thickly littered with dead earthworms. I've learned to treat rotenone with great caution. Microbes and Soil Fertility There are still other holistic standards to measure soil productivity. With more than adequate justification the great Russian soil microbiologist N.S. Krasilnikov judged fertility by counting the numbers of microbes present. He said, ". . soil fertility is determined by biological factors, mainly by microorganisms. The development of life in soil endows it with the property of fertility. The notion of soil is inseparable from the notion of the development of living organisms in it. Soil is created by microorganisms. Were this life dead or stopped, the former soil would become an object of geology [not biology]." Louise Howard, Sir Albert's second wife, made a very similar judgment in her book, _Sir Albert Howard in India._ "A fertile soil, that is, a soil teeming with healthy life in the shape of abundant microflora and microfauna, will bear healthy plants, and these, when consumed by animals and man, will confer health on animals and man. But an infertile soil, that is, one lacking in sufficient microbial, fungous, and other life, will pass on some form of deficiency to the plants, and such plant, in turn, who pass on some form of deficiency to animal and man." Although the two quotes substantively agree, Krasilnikov had a broader understanding. The early writers of the organic movement focused intently on mycorrhizal associations between soil fungi and plant roots as _the_ hidden secret of plant health. Krasilnikov, whose later writings benefited from massive Soviet research did not deny the significance of mycorrhizal associations but stressed plant-bacterial associations. Both views contain much truth. Krasilnikov may well have been the greatest soil microbiologist of his era, and Russians in general seem far ahead of us in this field. It is worth taking a moment to ask why that is so. American agricultural science is motivated by agribusiness, either by direct subsidy or indirectly through government because our government is often strongly influenced by major economic interests. American agricultural research also exists in a relatively free market where at this moment in history, large quantities of manufactured materials are reliably and cheaply available. Western agricultural science thus tends to seek solutions involving manufactured inputs. After all, what good is a problem if you can't solve it by profitably selling something. But any Soviet agricultural researcher who solved problems by using factory products would be dooming their farmers to failure because the U.S.S.R.'s economic system was incapable of regularly supplying such items. So logically, Soviet agronomy focused on more holistic, low-tech approaches such as manipulating the soil microecology. For example, Americans scientifically increase soil nitrogen by spreading industrial chemicals; the Russians found low-tech ways to brew bacterial soups that inoculated a field with slightly more efficient nitrogen-fixing microorgamsms. Soil microbiology is also a relatively inexpensive line of research that rewards mental cleverness over massive investment. Multimillion dollar laboratories with high-tech equipment did not yield big answers when the study was new. Perhaps in this biotech era, recombinant genetics will find high-tech ways to tailor make improved microorganisms and we'll surpass the Russians. Soil microorganism populations are incredibly high. In productive soils there may be billions to the gram. (One gram of fluffy soil might fill 1/2 teaspoon.) Krasilnikov found great variations in bacterial counts. Light-colored nonproductive earths of the North growing skimpy conifer trees or poor crops don't contain very many microorganisms. The rich, black, grain-producing soils of the Ukraine (like our midwestern corn belt) carry very large microbial populations. One must be clever to study soil microbes and fungi. Their life processes and ecological interactions can't be easily observed directly in the soil with a microscope. Usually, scientists study microorganisms by finding an artificial medium on which they grow well and observe the activities of a large colony or pure culture--a very restricted view. There probably are more species of microorganisms than all other living things combined, yet we often can't identify one species from another similar one by their appearance. We can generally classify bacteria by shape: round ones, rod-shaped ones, spiral ones, etc. We differentiate them by which antibiotic kills them and by which variety of artificial material they prefer to grow on. Pathogens are recognized by their prey. Still, most microbial activities remain a great mystery. Krasilnikov's great contribution to science was discovering how soil microorganisms assist the growth of higher plants. Bacteria are very fussy about the substrate they'll grow on. In the laboratory, one species grows on protein gel, another on seaweed. One thrives on beet pulp while another only grows on a certain cereal extract. Plants "understand" this and manipulate their soil environment to enhance the reproduction of certain bacteria they find desirable while suppressing others. This is accomplished by root exudates. For every 100 grams of above-ground biomass, a plant will excrete about 25 grams of root exudates, creating a chemically different zone (rhizosphere) close to the root that functions much like the culture medium in a laboratory. Certain bacteria find this region highly favorable and multiply prolifically, others are suppressed. Bacterial counts adjacent to roots will be in hundreds of millions to billions per gram of soil. A fraction of an inch away beyond the influence of the exudates, the count drops greatly. Why do plants expend energy culturing bacteria? Because there is an exchange, a _quid pro quo._ These same bacteria assist the plant in numerous ways. Certain types of microbes are predators. Instead of consuming dead organic matter they attack living plants. However, other species, especially actinomycetes, give off antibiotics that suppress pathogens. The multiplication of actinomycetes can be enhanced by root exudates. Perhaps the most important benefit plants receive from soil bacteria are what Krasilnikov dubbed "phytamins," a word play on vitamins plus _phyta_ or "plant" in Greek. Helpful bacteria exude complex water-soluble organic molecules that plants uptake through their roots and use much like humans need certain vitamins. When plants are deprived of phytamins they are less than optimally healthy, have lowered disease resistance, and may not grow as large because some phytamins act as growth hormones. Keep in mind that beneficial microorganisms clustering around plant roots do not primarily eat root exudates; exudates merely optimize environmental conditions to encourage certain species. The main food of these soil organisms is decaying organic matter and humus. Deficiencies in organic matter or soil pH outside a comfortable range of 5.75-7.5 greatly inhibit beneficial microorganisms. For a long time it has been standard "chemical" ag science to deride the notion that plant roots can absorb anything larger than simple, inorganic molecules in water solution. This insupportable view is no longer politically correct even among adherents of chemical usage. However, if you should ever encounter an "expert" still trying to intimidate others with these old arguments merely ask them, since plant roots cannot assimilate large organic molecules, why do people succeed using systemic chemical pesticides? Systemics are large, complex poisonous organic molecules that plants uptake through their roots and that then make the above-ground plant material toxic to predators. Ornamentals, like roses, are frequently protected by systemic chemical pesticides mixed into chemical fertilizer and fed through the soil. Root exudates have numerous functions beyond affecting microorganisms. One is to suppress or encourage the growth of surrounding plants Gardeners experience this as plant companions and antagonists. Walnut tree root exudates are very antagonistic to many other species. And members of the onion family prevent beans from growing well if their root systems are intermixed. Many crop rotational schemes exist because the effects of root exudates seem to persist for one or even two years after the original plant grew That's why onions grow very well when they are planted where potatoes grew the year before. And why farmers grow a three year rotation of hay, potatoes and onions. That is also why onions don't grow nearly as well following cabbage or squash. Farmers have a much easier time managing successions. They can grow 40 acres of one crop followed by 40 acres of another. But squash from 100 square feet may overwhelm the kitchen while carrots from the same 100 square feet the next year may not be enough. Unless you keep detailed records, it is hard to remember exactly where everything grew as long as two years ago in a vegetable garden and to correlate that data with this year's results. But when I see half a planting on a raised bed grow well and the adjacent half grow poorly, I assume the difficulty was caused by exudate remains from whatever grew there one, or even, two years ago. In 1990, half of crop "F" grew well, half poorly. this was due to the presence of crop "D" in 1989. The gardener might remember that "D" was there last year. But in 1991, half of crop "G" grew well, half poorly. This was also due to the presence of crop "D" two years ago. Few can make this association. These effects were one reason that Sir Albert Howard thought it was very foolish to grow a vegetable garden in one spot for too many years. He recommended growing "healing grass" for about five years following several years of vegetable gardening to erase all the exudate effects and restore the soil ecology to normal. Mycorrhizal association is another beneficial relationship that should exist between soil organisms and many higher plants. This symbiotic relationship involves fungi and plant roots. Fungi can be pathogenic, consuming living plants. But most of them are harmless and eat only dead, decaying organic matter. Most fungi are soil dwellers though some eat downed or even standing trees. Most people do not realize that plant roots adsorb water and water-soluble nutrients only through the tiny hairs and actively growing tips near the very end of the root. The ability for any new root to absorb nutrition only lasts a short time, then the hairs slough off and the root develops a sort of hard bark. If root system growth slows or stops, the plant's ability to obtain nourishment is greatly reduced. Roots cannot make oxygen out of carbon dioxide as do the leaves. That's why it is so important to maintain a good supply of soil air and for the soil to remain loose enough to allow rapid root expansion. When roots are cramped, top growth slows or ceases, health and disease resistance drops, and plants may become stressed despite applications of nutrients or watering. Other plants that do not seem to be competing for light above ground may have ramified (filled with roots) far wider expanses soil than a person might think. Once soil is saturated with the roots and the exudates from one plant, the same space may be closed off to the roots of another. Gardeners who use close plantings and intensive raised beds often unknowingly bump up against this limiting factor and are disappointed at the small size of their vegetables despite heavy fertilization, despite loosening the earth two feet deep with double digging, and despite regular watering. Thought about in this way, it should be obvious why double digging improves growth on crowded beds by increasing the depth to which plants can root. The roots of plants have no way to aggressively breakdown rock particles or organic matter, nor to sort out one nutrient from another. They uptake everything that is in solution, no more, no less while replacing water evaporated from their leaves. However, soil fungi are able to aggressively attack organic matter and even mineral rock particles and extract the nutrition they want. Fungi live in soil as long, complexly interconnected hair-like threads usually only one cell thick. The threads are called "hyphae." Food circulates throughout the hyphae much like blood in a human body. Sometimes, individual fungi can grow to enormous sizes; there are mushroom circles hundreds of feet in diameter that essentially are one single very old organism. The mushrooms we think of when we think "fungus" are actually not the organism, but the transitory fruit of a large, below ground network. Certain types of fungi are able to form a symbiosis with specific plant species. They insert a hyphae into the gap between individual plant cells in a root hair or just behind the growing root tip. Then the hyphae "drinks" from the vascular system of the plant, robbing it of a bit of its life's blood. However, this is not harmful