 Chapter 6 of Organic Gardeners' Composting This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Read by Betsy Bush in Marquette, Michigan, December 2008. Organic Gardeners' Composting by Steve Solomon Chapter 6, Verma Composting It was 1952 and Mr. Campbell had a worm bin. The shallow box, about two feet wide, by four feet long, resided under a work table in the tiny storeroom greenhouse adjacent to our grade school science class. It was full of what looked like black crumbly soil and zillions of small red wiggly worms. Not at all like the huge nightcrawlers I used to snatch from the lawn after dark to take fishing the next morning. Mr. Campbell's worms were fed used coffee grounds. The worms, in turn, were fed to salamanders, to Mr. Campbell's favorite fish, a fourteen-inch long smallmouth bass named Carl, to various snakes and to turtles living in aquariums around the classroom. From time to time the soil in the box was fed to his lush potted plants. Mr. Campbell was Verma Composting. This being before the age of ecology and recycling, he probably just thought of it as raising live food to sustain his educational menagerie. Though I never had reason to raise worms before, preparing to write this book perked my interest in every possible method of composting. Not comfortable writing about something I had not done, I built a small worm box, obtained a pound or so of brandling worms, made bedding, added worms, and began feeding the contents of my kitchen compost bucket to the box. To my secret surprise, Verma Composting works just as Mary Applehoff's book, Worms Eat My Garbage, said it would. Worm composting is amazingly easy. Although I admit there was a short learning curve and a few brief spells of sour odors that went away as soon as I stopped overfeeding the worms, I also discovered that my slap-dash homemade box had to have a drip catching pan underneath it. A friend of mine, who has run her own in-the-house home box for years, tells me that diluting these occasional insignificant and almost odorless dark-colored liquid emissions with several parts water makes them into excellent fertilizer for house plants or garden. It quickly became clear to me that composting with worms conveniently solves several recycling glitches. How does a northern homeowner process kitchen garbage in the winter when the ground and compost pile are frozen with vegetation to mix in? And can an apartment dweller without any other kind of organic waste except garbage and perhaps newspaper recycle these at home? The solution to both situations is Verma Composting. Worm castings, the end product of Verma Composting, are truly the finest compost you could make or buy. Compared to the volume of kitchen waste that will go into a worm box, the amount of castings you end up with will be small, though potent. Apartment dwellers could use worm castings to raise magnificent house plants or scatter surplus casts under the ornamentals or atop the lawn around their buildings or in the local park. In this chapter, I encourage you to at least try worm composting. I also answer the questions that people ask the most about using worms to recycle kitchen garbage. As the ever-enthusiastic Mary Applehoff said, I hope it convinces you that you too can vermicompost and that this simple process with the funny name is a lot easier to do than you thought. After all, if worms eat my garbage, they will eat yours too. Locating the Worms The species of worm used for vermicomposting has a number of common names, redworms, redwigglers, manureworms, or brandling worms. Redworms are healthy and active as long as they are kept above freezing and below 85 degrees. Even if the air temperature gets above 85 degrees, their moist bedding will be cooled by evaporation as long as air circulation is adequate. They are most active and will consume the most waste between 55 to 77 degrees, room temperatures. Redworms need to live in a moist environment but must breathe air through their skins. Keeping their bedding damp is rarely the problem. Preventing it from becoming waterlogged and airless can be a difficulty. In the south or along the Pacific coast, where things never freeze solid, worms may be kept outside in a shallow shaded pit as long as the spot does not become flooded or in a box in the garage or patio. In the north, worms are kept in a container that may be located anywhere with good ventilation and temperatures that stay above freezing but do not get too hot. Good spots for a worm box are under the kitchen sink, in the utility room or in the basement. The kitchen, being the source of the worm's food, is the most convenient, except for the danger of temporary odors. If you have one, a basement may be the best location because it is out of the way. While you are learning to manage your worms, there may be occasional short-term odor problems or fruit flies. These won't be nearly as objectionable if the box is below the house. Then, too, a vermicomposter can only exist in a complex ecology of soil animals. A few of these may exit the box and be harmlessly found about the kitchen. Ultra-festidious housekeepers may find this objectionable. Basements also tend to maintain a cooler temperature in summer. However, it is less convenient to take the compost bucket down to the basement every few days. Containers. Red worms need to breathe oxygen, but in deep containers, bedding can pack down and become airless, temporarily preventing the worms from eating the bottom material. This might not be so serious because you will stir up the box from time to time when adding new food. But anaerobic deep composition smells bad. If aerobic conditions are maintained, the odor from a worm box is very slight and not particularly objectionable. I notice the box's odor only when I am adding new garbage and the air flow is up close while stirring the material. A shallow box will be better aerated because it exposes much more surface area. Worm bins should be from 8 to 12 inches deep. I constructed my own box out of some old plywood. A top is not needed because the worms will not crawl out. In fact, when worm composting is done outdoors in shallow pits, few red worms exit the bottom by entering the soil because there is little air for them to eat. As air flow is vital, numerous holes between one quarter and one half inch diameter should be made in the bottom and the box must have small legs or cleats about one half or three quarters of an inch thick to hold it up enough to let air flow beneath. Having a drip catcher a large cookie tray works well is essential. Worms can also be kept in plastic containers like dish pans with holes punched in the bottom. As this book is being written, one mail order garden supply company even sells a tidy looking 19 inch by 24 inch by about 12 inch deep green plastic vermicomposting bin with drip pan lid and an initial supply of worms and bedding. If worm composting becomes more popular others will follow suit. Unless you are very strong do not compost a box larger than two by four feet because they will need to be lifted from time to time. Wooden boxes should last three or four years. If built of plywood use an exterior grade to prevent delamination. It is not advisable to make containers from rot resistant redwood or cedar because the natural oils that prevent rotting also may be toxic to worms. Sealed with polyurethane epoxy or other non-toxic waterproofing material worm boxes should last quite a bit longer. How big a box or how many boxes do you need? Each cubic foot of worm box can process about one pound of kitchen garbage each week. Naturally some weeks more garbage will go into the box than others. The worms will adjust to such changes. You can estimate box size by a weekly average amount of garbage over a three month time span. My own home garden supplied kitchen feeds two vegetable Eterian adults. Being year round gardeners our kitchen discards a lot of trimmings that would never leave a supermarket and we throw out as old salad greens that are still fresher than most people buy in the store. I'd say our two and a half gallon compost bucket is dumped twice a week in winter and three times in summer. From May through September while the garden is on a single two foot by four foot by twelve inch tall eight cubic foot box is not enough for us. Bedding Bedding is a high sea-to-end material that holds moisture provides an aerobic medium worms can exist in and allows you to bury the garbage in the box. The best beddings are also light and airy helping to maintain aerobic conditions. Bedding must not be toxic to worms because they'll eventually eat it. Bedding starts out dry and must be first soaked in water and then squeezed out until it is merely very damp. Several ordinary materials make fine bedding. You may use a single material bedding or may come to prefer mixtures. If you have a power shredder you can grind corrugated cardboard boxes handling ground up cardboard indoors may be a little dusty until you moisten it. Shredded cardboard is sold in bulk as insulation but this material has been treated with a fire retardant that is toxic. Gasoline powered shredders can also grind up cereal straw if it is dry and brittle. Alfalfa hay will decompose too rapidly. Similarly shredded newsprint makes fine bedding. The ink is not toxic being made from carbon black and oil. By tearing with the grain entire newspaper sections can rapidly be ripped into inch wide shreds by hand. Other shredded paper may be available from banks, offices or universities that may dispose of documents. Ground up leaves make terrific bedding. Here a power shredder is not necessary. An ordinary lawn mower is capable of chopping and bagging large volumes of dry leaves in short order. These may be prepared once a year and stored dry in plastic garbage bags until needed. A few 30 gallon bags will handle your vermicomp hosting for an entire year. However, dry leaves may be a little slower than other materials to rehydrate. Peat moss is widely used as bedding by commercial worm growers. It is very acid and contains other substances harmful to worms that are first removed by soaking the moss for a few hours and then hand squeezing the soggy moss until it is damp. Then a little lime is added to adjust the pH. Soil Red worms are heat tolerant litter dwellers that find little to eat in soil. Mixing large quantities of soil into worm bedding makes a very heavy box. However, the digestive system of worms grinds food using soil particles as the abrasive grit in the same way birds chew in their crop. A big handful of added soil will improve a worm box. A couple of tablespoons of powdered agricultural lime does the same thing while adding additional calcium to nourish the worms. Red worms The scientific name of the species used in vermicomp hosting is Isenia fotida. They may be purchased by mail from bait stores and these days even from mail order garden supply companies. Red worms may also be collected from compost in manure piles after they have heated and are cooling. Nightcrawlers and common garden worms play a very important part in the creation and maintenance of soil fertility. But these species are soil dwellers that require cool conditions. They cannot survive in a shallow worm box at room temperatures. Red worms are capable of very rapid reproduction at room temperatures in a worm box. They lay eggs encased in a lemon shaped cocoon about the size of a grain of rice from which baby worms will hatch. The cocoons start out pearly white but as the baby worms develop over a three week period the eggs change color to yellow then light brown and finally are reddish when the babies are ready to hatch. Normally two or three worms emerge from a cocoon. Hatchlings are whitish and semi-transparent and about one half inch long. It would take about a hundred and fifty thousand hatchlings to weigh one pound. A red worm hatchling will grow at an explosive rate and reach sexual maturity in four to six weeks. Once it begins breeding a red worm makes two to three cocoons a week for six months to a year. Or one breeding worm can make about a hundred babies and the babies are breeding about three months after the first eggs are laid. Though this reproduction rate is not the equal of yeast capable of doubling every twenty minutes still a several hundred fold increase every six months is amazingly fast. When vermicomposting the worm population increase is limited by available food and space and by the worms own waste products or casts. Worm casts are slightly toxic to worms. As the worm box starts out with fresh bedding it contains no casts. As time goes on the bedding is gradually broken down by cellulose eating microorganisms whose decay products are consumed by the worms and the box gradually fills with casts. As the proportion of casts increases reproduction slows and mature worms begin to die. However you will almost never see a dead worm in a worm box because their high protein bodies will be composed. You will quickly recognize worm casts. Once the bedding has been consumed and the box contains only worms worm casts and fresh garbage it is necessary to empty the casts replace the bedding and start the cycle over. How to do this will be explained in a moment. But first how many worms will you need to begin vermicomposting? You could start with a few dozen red worms patiently begin by feeding them tiny quantities of garbage every year. However you will almost certainly want to begin with a system that can consume all or most of your kitchen garbage right away. So for starters you will need to obtain two pounds of worms for each pound of garbage you will put into the box each day. Suppose in an average week your kitchen compost bucket takes in seven pounds of waste or about one gallon. That averages one pound per day. You will need about two pounds of worms. You will also need a box that holds six or seven cubic feet or about two by three feet by 12 inches deep. Each pound of worms needs three or four cubic feet of bedding. A better way to estimate box size is to figure that one cubic foot of worm bin can digest about one pound of kitchen waste a week without going anaerobic and smelling bad. Red worms are small and consequently worm growers sell them by the pound. There are about 1,000 mature breeders to the pound of young red worms. Bait dealers prefer to sell only the largest sizes or their customers complain. Red wigglers from a bait store may only count 600 to the pound. Wormraisers will sell pit run that costs much less. This is a mix of worms of all sizes and ages. Often the largest sizes will have already been separated out for sale as fish bait. That's perfectly okay. Since hatchlings run 150,000 to the pound and mature worms count about 600 to 700, the population of a pound of pit run may vary greatly. A reasonable pit run estimate is 2,000 to the pound. Actually, it doesn't matter what the number is. It is their weight that determines how much they'll eat. Red worms eat slightly more than their weight in food every day. If that is so, why did I recommend first starting vermicomposting with two pounds of worms for every pound of garbage? Because the worms you'll buy will not be used to living in the kind of bedding you'll give them, nor adjusted to the mix of garbage you'll feed them. Initially, there may be some losses. After a few weeks, the surviving worms will have adjusted. Most people have little tolerance for outright failure, but if they have a record of successes behind them minor glitches won't stop them. So it is vital to start with enough worms. The only time vermicomposting becomes odiferous is when the worms are fed too much. If they quickly eat all the food that they are given, the system runs remarkably smoothly and makes no offense. Please keep that in mind, since there may well be some short-lived problems until you learn to gauge their intake. Setting up a worm box Red worms need a damp but not soggy environment with moisture content more or less 75% by weight. But bedding material starts out very dry. So weigh the bedding and then add three times that weight of water. The rule to remember here is a pints a pound the world's round. Or one gallon of water weighs about eight pounds. As a gauge, it takes one to one and a half pounds of dry bedding for each cubic foot of box. Preparing bedding material can be a messy job. The best container is probably an empty garbage can though in a pinch it can be done in a kitchen sink or a couple of five gallon plastic buckets. Cautiously put half the probably dusty bedding in the mixing container. Add about one half the needed water and mix thoroughly. Then add two handfuls of soil the rest of the bedding and the balance of the water. Continue mixing until all the water is absorbed. Then spread the material evenly through your empty worm box. If you've measured correctly, no water should leak out the bottom vent holes and the bedding should not drip when a handful is squeezed moderately hard. Then add the worms. Spread your red worms over the surface of the bedding. They'll burrow under the surface to avoid the light and in a few minutes will be gone. Then add garbage. When you do this just that you spread the garbage over the entire surface and mix it in using a three-tined hand cultivator. This is the best tool to work the box with because the rounded points won't cut worms. Then cover the box. Mary Applehoff suggests using a black plastic sheet slightly smaller than the inside diameter of the container. Black material keeps out light and allows the worms to be active right on the surface. You may find that a plastic covering retains too much moisture and overly restricts air flow. When I covered my worm box with plastic it dripped too much. But then most of what I feed the worms is fresh vegetable material that runs 80-90% water. Other households may feed dryer materials like stale bread and leftovers. I found that on our diet it is better to keep the box in a dimly lit place and to use a single sheet of newspaper folded to the inside dimension of the box as a loose cover that encourages aeration somewhat reduces light on the surface and lessens moisture loss yet does not completely stop it. Feeding the worms Red worms will thrive on any kind of vegetable waste you create while preparing food. Here's a partial list to consider potato peelings, citrus rinds, the outer leaves of lettuce and cabbage, spinach stems, cabbage and cauliflower cores, celery butts, plate scrapings, spoiled food like old baked beans, moldy cheese and other leftovers, tea bags, eggshells, juicer pulp. The worm's absolute favorite seems to be used coffee grounds, though these can ferment and make a sour smell. Drip coffee lovers can put the filters in too. This extra paper merely supplements the bedding. Large pieces of vegetable matter can take a long time to be digested before tossing cabbage or cauliflower cores or celery butts into the compost bucket, cut them up into finer chunks or thin slices. It is not necessary to grind the garbage. Everything will break down eventually. Putting meat products into a wormbox may be a mistake. The odors from decaying meat can be foul and it has been known to attract mice and rats. Small quantities cut up finely and well dispersed will digest neatly. Bones are slow to decompose in a wormbox. If you spread the wormcasts as compost, it may not look attractive containing whitened picked clean bones. Chicken bones are soft and may disappear during vermicomposting. If you could grind bones before sending them to the worm bin, they would make valuable additions to your compost. Avoid putting non-biodegradable items like plastic bottle caps, rubber bands, aluminum foil, and glass into the wormbox. Do not let your cat use the worm bin as a litter box. The odor of cat urine would soon become intolerable while the urine is so high in nitrogen that it might kill some worms. Most seriously, cat manure can transmit the cysts of a protozoan disease organism called toxoplasma gondii, although most cats do not carry the disease. These parasites may also be harbored in adult humans without them feeling any ill effects. However, transmitted from mother to developing fetus, toxoplasma gondii can cause brain damage. You are going to handle the contents of your worm bin and don't want to have a chance of being infected with these parasites. Most people use some sort of plastic jar, recycled half gallon yogurt tub, empty waxed paper milk carton, or similar thing to hold kitchen garbage. Odors develop when anaerobic decomposition begins. If the holding tub is getting high, don't cover it, feed it to the worms. It is neater to add garbage in spots rather than mixing it throughout the bin. When feeding garbage into the worm bin, lift the cover, pull back the bedding with a three-tine hand cultivator, and make a hole about the size of your garbage container. Dump the waste into that hole and cover it with an inch or so of bedding. The whole operation only takes a few minutes. A few days later, the kitchen compost bucket will again be ready. Make methodically go around the box this way. By the time you get back to the first spot, the garbage will have become unrecognizable. The spot will seem to contain mostly worm casts and bedding, and will not give off strongly unpleasant odors when disturbed. Seasonal overloads On festive occasions, holidays, and during canning season, it is easy to overload the digestive capacity of a worm bin. The problem will correct itself without doing anything, but you may not be willing to live with anaerobic odors for a week or two. One simple way to accelerate the healing of an anaerobic box is to fluff it up with your hand cultivator. Vegetable, eatery, and households greatly increase the amount of organic waste they generate during summer, so do people who can or freeze when the garden is on. One vermicomposting solution to this seasonal overload is to start up a second summertime-only outdoor worm bin in the garage or other shaded location. Applehoff suggests an old leaky, galvanized wash tub for this purpose. The tub gets a few inches of fresh bedding and then is inoculated with a gallon of working vermicompost from the original bin. Extra garbage goes in all summer. Mary says, I have used for a worm bin annex an old leaky, galvanized wash tub kept outside near the garage. During canning season, the grape pulp, corn cobs, corn husks, bean cuttings, and other fall harvest residues went into the container. It got soggy when it rained and the worms got huge from all the food and moisture. We brought it inside at about the time of the first frost. The worms kept working the material until there was no food left. After six or eight months the only identifiable remains were a few corn cobs, squash seeds, tomato skins, and some decomposed corn husks. The rest was an excellent batch of worm castings and a very few hardy undernourished worms. Vacations Going away from home for a few weeks is not a problem. The worms will simply continue eating the garbage left in the bin. Eventually their food supply will decline enough that the population will drop. This will remedy itself as soon as you begin feeding the bin again. If a month or more is going to pass and your food or if the house will be unheated during the winter sabbatical you should give your worms to a friend to care for. Fruit flies Fruit flies can, on occasion, be a very annoying problem if you keep the worm bins in your house. They will not be present all the time nor in every house at any time but when they are present they are a nuisance. Fruit flies aren't unsanitary. They don't bite or seek out overripe fruit and fruit pulp. Usually fruit flies will hover around a food source that interests them. In high summer we have accepted having a few share our kitchen along with the enormous spread of ripe and ripening tomatoes atop the kitchen counter. When we're making fresh V7 juice on demand throughout the day they tend to congregate over the juicer's discharge pail that holds a mixture of vegetable pulps. If your worm bin contains these types of materials fruit flies may find it attractive. Applehoff suggests sucking them up with a vacuum cleaner hose if their numbers become annoying. Fruit flies are a good reason for those of teutonic tidiness to vermiculture in the basement or outside the house if possible. Maintenance After a new bin has been running for a few weeks you will see the bedding becoming darker and will spot individual worm casts. Even though food is steadily added the bedding will gradually vanish. Extensive decomposition of the bedding by other small soil animals and microorganisms begins to be significant. As worm casts become a large proportion of the bin, conditions deteriorate for the worms. Eventually the worms suffer and their number and activity begins to drop off. Differences in bedding, temperature, moisture, and the composition of your kitchen's garbage will control how long it takes, but eventually you must separate the worms from their castings and put them into fresh bedding. If you're using vermicomposting year-round it probably will be necessary to regenerate the box about once every four months. There are a number of methods for separating red worms from their castings. Hand sorting works well after a worm box has first been allowed to run down a bit. The worms are not fed until almost all their food has been consumed and they are living in nearly pure castings. Then lay out a thick sheet of plastic at least four feet square on the ground floor or on a table and dump the contents of the worm box on it. Make six to nine cone-shaped piles. You'll see worms all over. If you're working inside make sure there is bright light in the room. The worms will move into the center of each pile. Wait five minutes or so and then delicately scrape off the surface with each conical heap one after another. By the time you finish with the last pile the worms will have retreated further and you can begin with the first heap again. You repeat this procedure gradually scraping away casts until there is not much left of the conical heaps. In a surprisingly short time the worms will all be squirming in the center of a small pile of castings. There is no need to completely separate the worms from all the castings. Now gather up the worms and place them in fresh bedding to start anew without further inconvenience for another four months. Use the vermicompost on house plants in the garden or save it for later. Hand sorting is particularly useful if you want to send a few pounds of red worms to a friend. Dividing the box is another simpler method. You simply remove about two-thirds of the box's contents and spread it on the garden. Then refill the box with fresh bedding and distribute the remaining worms, castings, and food still in the box. Plenty of worms and egg cancoons will remain to populate the box. The worms that you dumped on the garden will probably not survive there. A better method of dividing a box prevents wasting so many worms. All of the box's contents are pushed to one side, leaving one-third to one-half of the box empty. New bedding and fresh food are put on the new side. No food is given to the old side for a month or so. By that time virtually all the worms will have migrated to the new side. Then the old side may be emptied and refilled with fresh bedding. People in the north may want to use a worm box primarily in winter when their composting methods are inconvenient or impossible. In this case, start feeding the bin heavily from fall through spring and then let it run without much new food until mid-summer. By that time there will be only a few worms left alive in a box of castings. The worms may then be separated from their castings. The box recharged with bedding and the remaining worms can be fed just enough to increase rapidly so that by autumn there will again be enough to eat all your winter garbage. Garbage can composting Here's a large capacity vermicomposting system for vegetable etarians and big families. It might even have sufficient digestive capacity for serious juice makers. You'll need two or three 20 to 30 gallon garbage cans, metal or plastic. In two of them, drill numerous half inch diameter holes from bottom to top and in the lid as well. The third can is used as a tidy way to hold extra dry bedding. Begin the process with about 10 inches of moist bedding material and worms on the bottom of the first can. Add garbage on top without mixing it in and occasionally sprinkle a thin layer of fresh bedding. Eventually the first can will be full though it will digest hundreds of gallons of garbage before that happens. When finally full the bulk of its contents will be finished worm casts and will contain few if any worms. Most of the remaining activity will be on the surface where there is fresh food and more air. Filling the first can may take six months to a year. Then start the second can by adding a few inches of the first which contains most of the worms into a few inches of fresh bedding on the bottom of the second can. I'd wait another month for the worms left in the initial can to finish digesting all the remaining garbage. Then you have 25 to 30 gallons of worm casts ready to be used as compost. Painting the inside of metal cans with ordinary enamel when they have been emptied will greatly extend their life. You might run two Verma composting garbage cans at once. End of Chapter 6 Chapter 7 of Organic Gardener's Composting This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org read by Betsy Bush February 2009 Organic Gardener's Composting by Steve Solomon Part 2 Composting for the Food Gardener Introduction There is a great deal of confusion in the gardening world about compost organic matter, humus, fertilizer, and their roles in soil fertility, plant health, animal health, human health and gardening success. Some authorities seem to recommend as much manure or compost as possible. Most show inadequate concern about its quality. The slick books published by a major petrochemical corporation correctly acknowledge that soil organic matter is important but give rather vague guidelines as to how much while focusing on chemical fertilizers. Organic gardeners denigrate chemicals as though they were of the devil. And like J.I. Rodale in the organic front, advise is it practical to run a garden exclusively with the use of compost without the aid of so-called chemical or artificial fertilizers? The answer is not only yes, but in such case you will have the finest vegetables obtainable, vegetables fit to grace the table of the most exacting gourmet. Since the 1950s, a government funded laboratory at Cornell University has cranked out seriously flawed studies proving that food raised with chemicals is just as or even more nutritious than organically grown food. The government's investment in scientific research was made to counter unsettling to various economic interest groups nutritional and health claims that the organic farming movement had been making. For example, in The Living Soil, Lady Eve Belfour observed, I have lived a healthy country existence practically all my life and for the last 25 years of it I have been actively engaged in farming. I am physically robust and have never suffered a major illness. But until 1938 I was seldom free in winter from some form of rheumatism and from November to April I invariably suffered from a continual succession of head colds. I started making compost by Howard's method using it first on the vegetables for home consumption. That winter I had no colds at all and almost for the first time in my life was free from rheumatic pain even in prolonged spells of wet weather. 50 years later there still exists an intensely polarized dispute about the right way to garden and farm. People who are comfortable disagreeing with authority and that believe there is a strong connection between soil fertility and the consequent health of plants, animals and humans living on that soil tend to side with the organic camp. People who consider themselves practical or scientific tend to side with the mainstream agronomists and consider chemical agriculture as the only method that can produce enough to permit industrial civilization to exist. For many years I was confused by all this. Have you been too? Or have you taken a position on this controversy and feel that you don't need more information? I once thought the organic camp had all the right answers but years of explaining soil management in gardening books made me reconsider and reconsider again questions like why is organic matter so important in soil and how much and what kind do we need? I found these subjects still needed to have clearer answers this book attempts to provide those answers and put aside ideology. A brief history of the organic movement How did all this irresolvable controversy begin over something that should be scientifically obvious? About 1900 experts increasingly encouraged farmers to use chemical fertilizers and to neglect maneuvering and composting as unprofitable and unnecessary. At the time this advice seemed practical because chemicals did greatly increase yields and profits while chemistry plus is farm machinery minus livestock greatly eased the farmer's workload allowed the farmer to abandon the production of low value fodder crops and concentrate on higher value cash crops. Perplexing new farming problems diseases, insects, and loss of seed vigor began appearing after World War I. These difficulties did not seem obviously connected to industrial agriculture, to abandonment of livestock, maneuvering, composting, and dependence on chemistry. The troubled farmers saw themselves as innocent victims of happenstance, needing to hire the chemical plant doctor much as sick people are encouraged by medical doctors to view themselves as victims who are totally irresponsible for creating their condition and capable of curing it without costly and dangerous medical intervention. Farming had been done holistically before Roman times. Farms inevitably included livestock and animal manure or compost made with manure or green manures were the main sustainers of soil fertility. In 1900, productive farm soils still contained large reserves of humus for millennia of maneuvering. As long as humus is present in quantity small, affordable amounts of chemicals actually do stimulate growth, increased yields of crop profits, and plant health doesn't suffer nor do diseases and insects become plagues. However, humus is not a permanent material and is gradually decomposed. Elimination of maneuvering steadily reduced humus levels and consequently decreased the life in the soil. And, as will be explained a little later, nitrogen rich fertilizers accelerate humus loss. With the decline of organic matter new problems with plant and animal health gradually developed while insect predation worsened and profits dropped because soils declining in humus need ever larger amounts of fertilizer to maintain yields. These changes developed gradually and erratically and there was a long lag between the first dependence on chemicals, the resulting soil addiction, and steady increases in farm problems. A new alliance of scientific experts, universities, and agribusiness interests had self-interested reasons to identify other causes than loss of soil humus for the new problems. The increasingly troubled farmers' attention was thus fixated on fighting against plant and animal diseases and insects with newer and better chemicals. Just as with farm animals, human health also responds to soil fertility. Industrial agriculture steadily lowered the average nutritional quality of food and gradually increased human degeneration. But these effects were masked by a statistical increase in human lifespan due to improved public sanitation, vaccinations, and starting in the 1930s the first antibiotics. As statistics we were living longer but as individuals we were feeling poorer. Actually most of the statistical increase in lifespan is from children that are now surviving childhood diseases. I contend that people who made it to seven years old a century ago had a chance more or less equal to hours of surviving past seventy with a greater probability of feeling good in middle and old age. People have short memories and tend to think that things always were as they are in the present. Slow but continuous increases in nutritionally related diseases like tooth decay, periodontal disease, diabetes, heart disease, birth defects, mental retardation, drug addiction, or cancer are not generally seen as a new problem. While subtle reductions in the feeling of well-being go unnoticed. During the 1930s a number of far-seeing individuals began to worry about the social liabilities from chemically dependent farming. Doctors Robert McCarrison and Weston Price addressed their concerns to other health professionals. Rudolf Steiner, observing that declines in human health were preventing his disciples from achieving spiritual betterment, started the gentle biodynamic farming movement. Steiner's principal English-speaking followers, Pfeiffer and Koff, wrote about biological farming and gardening extensively and well. Professor William Albrecht, chairman of the soil department of the University tried to help farmers raise healthier livestock and made unemotional but very explicit connections between soil fertility, animal and human health. Any serious gardener or person interested in health and preventive medicine will find the books of all these unique individuals well worth reading. I doubt that the writings and lectures of any of the above individuals would have sparked a bitter controversy like the intensely ideological study that developed between the organic gardening and farming movement and the agribusiness establishment. This was the doing of two energetic and highly puritanical men, Sir Albert Howard and his American disciple, J.I. Rodale. Howard's criticism was correctly based on observations of improved animal and human health as a result of using compost to build soil fertility, probably concluding that the average farmer's weak ethical condition would be unable to resist the apparently profitable allures of chemicals unless their moral sense was outraged. Howard undertook an almost religious crusade against the evils of chemical fertilizers. Notice the powerful emotional loading carried in this brief excerpt from Howard's soil and health. Artificial fertilizers lead to artificial nutrition, artificial animals and finally to artificial men and women. Do you want to be artificial? Rodale's contentious organic front makes readers feel morally deficient if they do not agree about the vital importance of recycling organic matter. The Chinese do not use chemical fertilizers. They return to the land every bit of organic matter they can find. In China if you burned over a field or a pile of vegetable rubbish, you would be severely punished. There are many fantastic stories as to the lengths the Chinese will go through in an experimental matter. A traveler told me that while he was on the toilet in a Shanghai hotel, two men were waiting outside to rush in and make way with the stuff. Perhaps you too should be severely punished for wasting your personal organic matter. Rodale began proselytizing for the organic movement about 1942. With an intensity unique to ideologs he attacked chemical companies, attacked chemical fertilizers, attacked chemical pesticides, and attacked the scientific agricultural establishment. With a limited technical education behind him, the well-meaning Rodale occasionally made over statements, wrote over simplifications as science, and uttered scientific absurdities as fact. And he attacked, attacked, attacked all along a broad organic front. So the objects of his attacks defended, defended, defended. The deal of confusion was generated from the contradictions between Rodale's self-righteous and sometimes scientifically vague positions and the amused defenses of the smug scientific community. Donald Hopkins' chemical humus and the soil is the best, most humane, and emotionally generous defense against the extremism of Rodale. Hopkins makes hash of many organic principles while still upholding the vital role of humus. Anyone who thinks of themselves as a supporter of organic farming and gardening should first dig up this old out-of-print book and come to terms with Hopkins' arguments. Organic versus establishment hostilities continued unabated for many years. After his father's death, Rodale's son and heir to the publishing empire, Robert, began to realize that there was a sensible middle-ground. However, I suppose, Robert seemed communicating a less ideological message as a problem. Most of the readers of organic gardening and farming magazine and the buyers of organic gardening books published by Rodale Press weren't open to ambiguity. I view organic gardeners largely as examples of American puritanism who want to possess a clear, simple system of capital T truth that brooks no exceptions and has no complications or gray areas. Organic as a movement had come to be defined by Rodale publications as growing food by using an approved list of substances that were considered good and virtuous while shunning another list that seemed to be considered of the devil similar to kosher and non-kosher food in the Orthodox Jewish religion and like other puritans the organic faithful could consider themselves superior human beings. But other agricultural reformers have understood that there are gray areas that chemicals are not all bad or all good and that other sane and holistic standards can be applied to decide what is the best way to go about raising crops. These people began to discuss new agricultural methods like integrated pest management, IPM or low input sustainable agriculture, LISA systems that allowed a minimal use of chemistry without abandoning the focus of vital organic matters vital importance. My guess is that some years back Bob Rodale came to see the truth of this giving him a problem. He did not want to threaten a major source of political and financial support so he split off the farming from organic gardening and farming magazine and started two new publications one called The New Farm where safely away from less educated unsophisticated eyes he could discuss minor alterations in the organic faith without upsetting the readers of organic gardening. Today's Confusions I have offered this brief interpretation of the organic gardening and farming movement primarily for those gardeners who, like me, learned their basics from Rodale Press. Those who do not now cast this heretical book down in disgust but finish it will come away with a broader more scientific understanding of the matter some certainty about how much compost you really need to make and use and the role that both compost and fertilizers can have in creating and maintaining the level of soil fertility needed to grow a great vegetable garden. Chapter 7 Humus and Soil Productivity Books about hydroponics sound plausible that is until you actually see the results. Plant nutrient solutions may be huge but look a little off sickly and weak somehow. Without a living soil plants cannot be totally healthy or grow quite as well as they might. By focusing on increasing and maximizing soil life instead of adding chemical fertility organic farmers are able to grow excellent cereals and fodder. On richer soils, they can even do this for generations, perhaps even for millennia, without bringing plant nutrients from elsewhere. If little or no product is sent away from the farm this subsistence approach may be a permanent agricultural system but even with a healthy ecology few soils are fertile enough by themselves to permit continuous export of their mineral resources by selling crops at market. Take one step further. Cereals are mostly derived from hardy grasses while other field crops have similar abilities to thrive while being offered relatively low levels of nutrients. With good management fertile soils are able to present these lower nutritional levels to growing plants without amendment or fortification with potent concentrated nutrient sources but most vegetables demand far higher levels of support. Few soils, even fertile soils that have never been farmed will grow vegetables without improvement. Farmers and gardeners must increase fertility significantly if they want to grow great vegetables. The choices they make while doing this can have a strong effect not only on their immediate success or failure but on the actual nutritional quality of the food that they produce. How Humus Benefits Soil The roots of plants, soil animals and most soil microorganisms need to breathe oxygen. Like other oxygen burners they expel carbon dioxide. For all of them to grow well and be healthy the earth must remain open allowing air to enter and leave freely. Otherwise carbon dioxide builds up to toxic levels. Imagine yourself being suffocated by a plastic bag tied around your neck. It would be about the same thing to a root trying to live in compacted soil. A soil consisting only of rock particles tends to be airless. A scientist would say it has a high bulk density or lacked pore space. Only coarse sandy soil remains light and open without organic matter. Few soils are formed only of coarse sand. Most are mixtures of sand silt and clay. Sands are sharp sided relatively large rock particles similar to table salt or refined white sugar. Regular edges keep sand particles separated and allow the free movement of air and moisture. Silt is formed from sand that has weathered to much smaller sizes similar to powdered sugar or talcum powder. Through a magnifying lens the edges of silt particles appear rounded because weak soil acids have actually dissolved them away. A significant amount of the nutrient content of these decomposed rock particles has become plant food or clay. Silt particles can compact tightly leaving little space for air. As soil acids break down silt the less soluble portions recombine into clay crystals. Clay particles are much smaller than silt grains. It takes an electron microscope to see the flat layered structures of clay molecules. Shales and slates are rocks formed by heating and compressing clay. Their layered fracture planes mimic the molecules from which they were made. Pure clay is heavy, airless, and a very poor medium for plant growth. Humusless soils that are mixtures of sand, silt and clay can become extremely compacted and airless because the smaller silt and clay particles sift between the larger sand bits and densely fill all the soil. These soils can also form very hard crusts that resist the infiltration of air, rain, or irrigation water and prevent the emergence of seedlings. Surface crusts form exactly the same way that concrete is finished. Have you ever seen a finisher screed a concrete slab? First smooth boards and then large trowels are run back and forth over liquid concrete. The motion separates the tiny bits of fine sand and cement from denser bits of gravel. The fines rise to the surface where they are troweled into a thin smooth skin. The same thing happens when humusless soil is rained on or irrigated with sprinklers emitting a coarse heavy spray. The droplets beat on the soil mechanically separating the lighter fines, in this case silt and clay from larger denser particles. The sand particles sink. The fines rise and dry into a hard impenetrable crust. Organic matter decomposing in soil opens and loosens soil and makes the earth far more welcoming to plant growth. Its benefits are both direct and indirect. Decomposing organic matter mechanically acts like springy sponges that reduce compaction. However, rotting is rapid and soon this material and its effect is virtually gone. You can easily create this type of temporary result by tilling a thick dusting of peat moss into some poor soil. A more significant and longer lasting soil improvement is created by microorganisms and earthworms whose activities makes particles of sand, silt, and clay cling strongly together and form large, irregularly shaped grains called aggregates or crumbs that resist breaking apart. A well-developed crumb structure gives soil a set of qualities farmers and gardeners delightfully refer to as good tilf. The difference between good and poor tilf is like night and day to someone working the land. For example, if you rotary till unaggregated soil into a fluffy seed bed, the first time it is irrigated, rained on, or stepped on, it slumps back down into an airless mass and probably develops a hard crust as well. However, a soil with good tilf will permit multiple irrigations and a fair amount of foot traffic without compacting or crusting. Crumbs develop as a result of two similar interrelated processes. Earthworms and other soil animals make stable humus crumbs, as soil, clay, and decomposing organic matter pass through their digestive systems. The casts or scats that emerge are crumbs. Freeliving soil microorganisms also form crumbs. As they eat organic matter, they secrete slimes and gums that firmly cement fine soil particles together into long-lasting aggregates. I sadly observe what happens when farmers allow soil organic matter to run down every time I drive in the country. Soil color that should be dark changes to light because mineral particles themselves are usually light-covered or reddish. The rich black or chestnut tone soil can get is organic matter. Puddles form when it rains hard on perfectly flat humusless fields and may stand for hours or days, driving out all soil air, drowning earthworms, and suffocating crop roots. On sloping fields the water runs off rather than percolating in. Evidence of this can be seen in muddy streams and in more severe cases by little rills or mini gullies across the field caused by fast sweeping water, sweeping up soil particles from the crusted surface as it leaves the field. Later the farmers will complain of drought or infertility and seek to support their crops with irrigation and chemicals. Actually if all the water that had fallen on the field had percolated into the earth the crops probably would not have suffered at all even from extended spells without rain. These same humusless fields lose a lot more soil in the form of large clouds when tilled in a dryish state. The greatest part of farm soil erosion is caused by failing to maintain necessary levels of humus. As a nation America is losing its best cropland at a non-sustainable rate. No civilization in history has yet survived the loss of its prime farmland. Before industrial technology placed thousands of times more force into the hands of the farmer we managed to make an impoverished semi-desert out of every civilized region within 1,000 to 1,500 years. This sad story is told in Carter and Dale's fascinating but disturbing book called Top Soil and Civilization that I believe should be read by every thoughtful person. Unless we significantly alter our improved farming methods we will probably do the same to America in another century or two. The Earthworm's Role Soil Fertility Soil fertility has been engaged by different measures. Howard repeatedly insisted that the only good yardstick was humus content. Others are so impressed by the earthworm's essential functions that they count worms per acre and say that this number measures soil fertility. The two standards of evaluation are closely related. When active some species of earthworms daily eat a quantity of soil equal to their own body weight. After passing through the worm's gut this soil has been chemically altered. Minerals especially phosphorus which tend to be locked up as insoluble calcium phosphate and consequently unavailable to plants become soluble in the worm's gut and thus available to nourish growing plants. And nitrogen, unavailably held in organic matter, is altered by soluble nitrate nitrogen. In fact, compared to the surrounding soil, worm casts are five times as rich in nitrate nitrogen. Twice as rich in soluble calcium, contain two and one half times as much available magnesium, are seven times as rich in available phosphorus and offer plants eleven times as much potassium. Earthworms are equally capable of making trace minerals available. Highly fertile earthworm casts can amount to a large proportion of the entire soil mass. When soil is damp and cool enough to encourage earthworm activity an average of 700 pounds of worm casts per acre are produced each day. Over a year's time in the humid eastern United States 100,000 pounds of highly fertile casts per acre may be generated. Imagine, that's like 50 tons of low-grade fertilizer per acre per year containing more readily available NPK, calcium, magnesium, and so forth than farmers applied to grow cereal crops like wheat, corn, or soybeans. A level of fertility that will grow wheat is not enough nutrition to grow vegetables, but earthworms can make a major contribution to the garden. At age 28 Charles Darwin presented On the Formation of Mold to the Geological Society of London. This lecture illustrated the amazing churning effect of the earthworm on soil. Darwin observed some chunks of lime that had been left on the surface of a meadow. A few years later they were found several inches below the surface. Darwin said this was the work of earthworms, depositing castings that sooner or later spread out and cover any object left on the surface. In a later book Darwin said the plow is one of the most ancient and most valuable of man's inventions. But long before he existed the land was in fact regularly plowed and still continues to be thus plowed by earthworms. It may be doubted whether there are many other animals which have played so important a part in the history of the world as have these lowly organized creatures. Earthworms also prevent runoff. They increase percolation of water into fine textured soils by making a complex system of collected channels or tunnels throughout the top soil. In one study soil lacking worms had an absorption rate of 0.2 inches of rainfall per minute. Earthworms were added and allowed to work over that soil sample for one month. Then infiltration rates increased to 0.9 inches of rainfall per minute. Much of what we know about earthworms is due to Dr. Henry Hopp who worked for the United States Department in the 1940s. Dr. Hopp's interesting booklet what every gardener should know about earthworms is still in print. In one Hopp research project some very run down clay soil was placed in six large flower pots. Nothing was done to a pair of control pots. Fertilizer was blended in and grass sod grown on two others while mulch was spread over two more. Then worms were added to a pair of pots. In short order all of the worms added to the unimproved pot were dead. There was nothing in that soil to feed them. The sod alone increased percolation but where the sod or mulch fed a worm population infiltration of water was far better. Amendment to Clay Soil None Percolation rate in inches per minute without worms 0.0 Amendment to Clay Soil Grass and Fertilizer Percolation rate in inches per minute without worms 0.2 With worms 0.8 Amendment to Clay Soil Mulch Percolation rate in inches per minute without worms 0.0 With worms 1.5 Most people who honestly consider these facts conclude that the earthworms activities are a major factor in soil productivity. Study after scientific study has shown that the quality and yield of pastures is directly related to their earthworm count. So it seems only reasonable to evaluate soil management practices by their effect on earthworm counts. Earthworm populations will vary enormously according to climate and native soil fertility. Earthworms need moisture. Few, if any, will be found in deserts. Highly mineralized soils that produce a lot of biomass will naturally have more worms than infertile soils lacking humus. Dr. Hopps surveyed worm populations in various farm soils. The table below shows what a gardener might expect to find in their own garden by contrasting samples from rich and poor soils. The data also suggests a guideline for how high worm populations might be usefully increased by adding organic matter. The worms were counted at their seasonal population peak by carefully examining a section of soil equally 1 foot square by 7 inches deep. If you plan to take a census in your own garden, keep in mind that earthworm counts will be highest in spring. Location, Marcellus, New York. Worms per square foot 38. Worms per acre 1,600,000. Location, Ithaca, New York. Worms per square foot 4. Worms per acre 190,000. Location, Frederick, Maryland. Worms per square foot 50. Worms per acre 2,200,000. Location, Beltsville, Maryland. Worms per square foot 8. Worms per acre 250,000. Location, Zanesville, Ohio. Worms per square foot 37. Worms per acre 1,600,000. Location, Kosakton, Ohio. Worms per square foot 5. Worms per acre 220,000. Location, Mayakwez, Puerto Rico. Note, because of the high rate of bacterial decomposition, few earthworms are found in tropical soils, unless they are continuously amended with substantial quantities of organic matter. And note, worms per square foot 6. Worms per acre 260,000. Earthworms are inhibited by acid soils and or soils deficient in calcium. Far larger populations of worms live in soils that weathered out of underlying limestone rocks. In one experiment, earthworm counts in a pasture went up from 51,000 per acre in acid soil to 441,000 per acre two years after lime and a non-acidifying chemical fertilizer were spread. Rodale and Howard loudly and repeatedly contended that chemical fertilizers decimate earthworm populations. Swept up in what I view as a self-righteous crusade in the experiment, they included all fertilizers in this category for tactical reasons. Howard especially denigrated sulfate of ammonia and single-superphosphate as earthworm poisons. Both of these chemical fertilizers are made with sulfuric acid and have a powerful acidifying reaction when they dissolve in soil. Rodale correctly pointed out that golf course groundskeepers use repeated applications of cutting greens. Small mounds of worm casts made by nightcrawlers ruin the green's perfectly smooth surface so these worms are the bane of greenskeepers. However, ammonium sulfate does not eliminate or reduce worms when the soil contains large amounts of chalk or other forms of calcium that counteract acidity. The truth of the matter is that worms eat decaying organic matter and any soil amendment that increases plant growth will increase earthworm food supply and thus worm population. Using lime as an antidote to acid-based fertilizers prevents making the soil inhospitable to earthworms and many chemical fertilizers do not provoke acid reactions. The organic movement loses this round but not the battle and certainly not the war. Food supply primarily determines earthworm population. To increase their numbers it is necessary to bring in additional organic 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%. 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 Isenia fotida 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 only in decomposing manure or other protonaceous organic waste with a low C to 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 moisture. 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 inhospitable hot and dry during summer worms I view and there is 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 rye grass, even a thin mulch of grass clippings or weeds can serve as the food source worms need. Dr. Hoppe 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 cleanup 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-7 one of the most commonly used home garden chemical pesticides is deadly to earthworms even at low levels. Malothion is moderately toxic to worms. Diozyanon 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, rotinone an insecticide derived from a tropical root called deris is as poisonous to humans as organophosphate chemical pesticides. Even in very dilute amounts rotinone is highly toxic to fish and other aquatic life. Great care must be taken to prevent it from getting into waterways. In tropics people traditionally harvest great quantities of fish by tossing a handful of powdered deris a root containing rotinone into the water, waiting a few minutes and then scooping up stunned dead and dying fish by the ton. Rotinone is also deadly to earthworms. However, rotinone 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 rotinone 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 rotinone 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 rotinone 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 number 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. Where 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, fungus, 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 Kristilnikov had a broader understanding. The early writers of the organic movement focused intently on microbial associations between soil fungi and plant roots as the hidden secret of plant health. Kristilnikov, whose later writings benefited from massive Soviet research, did not deny the significance of microbial associations but stressed plant bacterial associations. Both views contain much truth. Kristilnikov 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 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 USSR'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 micro-ecology. 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 microorganisms. Soil micro-biology 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 will surpass the Russians. Soil micro-organism populations are incredibly high. In productive soils, there may be billions to the gram. One gram of fluffy soil might fill half a teaspoon. Krasilnikov found great variations in bacterial counts. Light-colored, non-productive 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 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. The fraction of an inch away from 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 of the ectinomycetes give off antibiotics that suppress pathogens. The multiplication of ectinomycetes can be enhanced by root exudates. Perhaps the most important benefit plants receive from soil bacteria are what Krasilnikov dubbed vitamins. 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 vitamins they are less than optimally healthy, have lowered disease resistance and may not grow as large because some vitamins act as growth hormones. Keep in mind that beneficial microorganisms clustering around plant roots do not primarily eat root 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 to 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 a hundred square feet may overwhelm the kitchen, while carrots from the same hundred 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 exodate 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 exodate effects and restore the soil ecology to normal. Microsial 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 absorb 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 heavily fertilization despite loosening the earth two feet deep 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 break down 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 the 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 predation because as the root grows a bark develops around the hyphae. The bark pinches off the hyphae and it rapidly decays inside the plant making a contribution of nutrients that the plant couldn't otherwise obtain. Hyphae breakdown products may be in the form of complex organic molecules that function as vitamins for the plant. Not all plants are capable of forming microbial associations. Members of the cabbage family, for example, do not. However, if the species can benefit from such an association and does not have one, then despite fertilization the plant will not be as healthy as it could be nor grow as well. This phenomenon is commonly seen in conifer tree nurseries where seedling beds are first completely sterilized with harsh chemicals and then tree seeds sown. Although thoroughly fertilized, the tiny trees grow slowly for a year or so. Then as spores of microbial fungi begin falling on the beds and their hyphae become established, scattered trees begin to develop the necessary symbiosis and their growth takes off. On a bed of two-year-old seedlings many individual trees are head and shoulders above the others. This is not due to superior genetics or erratic soil fertility. These are the individuals with microbial association. Like other beneficial microorganisms, microbial fungi do not primarily eat plant vascular fluid. Their food is decaying, organic matter. Here's yet another reason to contend that soil productivity can be measured by humus content. End of chapter 7