Earth Conservation > Technology

"Anyone starting out from scratch to plan a civilization would hardly have designed such a monster as our collective sewage system. Its existence gives additional point to the sometimes asked question, Is there any evidence of intelligent life on the planet Earth?"
G. R. Stewart

There are four general ways to deal with human excrement. The first is to dispose of it as a waste material. People do this by defecating in drinking water supplies, or in outhouses or latrines. Most of this waste ends up dumped, incinerated, buried in the ground, or discharged into waterways.

The second way to deal with human excrement is to apply it raw to agricultural land. This is popular in Asia where "night soil," or raw human excrement, is spread on fields. Although this keeps the soil enriched, it also acts as a vector, or route of transmission, for disease organisms. In the words of Dr. J. W. Scharff, former chief health officer in Singapore, " Though the vegetables thrive, the practice of putting human [manure] directly on the soil is dangerous to health. The heavy toll of sickness and death from various enteric diseases in China is well-known." The World Health Organization adds, " Night soil is sometimes used as a fertilizer, in which case it presents great hazards by promoting the transmission of food-borne enteric [intestinal] disease, and hookworm." (It is interesting, incidentally, to note Dr. Scharff's only alternative to the use of raw night soil: " We have been inclined to regard the installation of a water-carried system as one of the final aims of civilization.") This book, therefore, is not about recycling night soil by raw applications to land, which is a practice that should be discouraged when sanitary alternatives, such as composting, are available.

The third way to deal with human excrement is to slowly compost it over an extended period of time. This is the way of most commercial composting toilets. Slow composting generally takes place at temperatures below that of the human body, which is 37�C or 98.6�F. This type of composting eliminates most disease organisms in a matter of months, and should eliminate all human pathogens eventually. Low temperature composting creates a useful soil additive that is at least safe for ornamental gardens, horticultural, or orchard use.

Thermophilic composting is the fourth way to deal with human excrement. This type of composting involves the cultivation of heat-loving (thermophilic) microorganisms in the composting process. Thermophilic microorganisms, such as bacteria and fungi, can create an environment in the compost which destroys disease organisms that can exist in humanure, converting humanure into a friendly, pleasant-smelling, humus safe for food gardens. Thermophilically composted humanure is entirely different from night soil. Perhaps it is better stated by the experts in the field: " From a survey of the literature of night soil treatment, it can be clearly concluded that the only fail-safe night soil method which will assure effective and essentially total pathogen inactivation, including the most resistant helminths [intestinal worms] such as Ascaris [roundworm] eggs and all other bacterial and viral pathogens, is heat treatment to a temperature of 55� to 60�C for several hours." The experts are specifically referring to the heat of the compost pile

"One of the most fascinating aspects of composting is that it still retains elements of art . . . Producing good compost requires the same level of knowledge, engineering, skill, and art required for producing good wine."
Roger Haug - The Practical Handbook of Compost Engineering

I first moved out to the country and started living off the land at the age of 22. Being fresh out of college, I knew little of practical value. One word that was a mystery to me was "compost"; another was "mulch." Although I didn't know what either of these were, I knew they had something to do with organic gardening, and that's what I wanted to learn about. Of course, it didn't take me long to understand mulch. Anyone who can throw a layer of straw on the ground can mulch. But compost took a bit longer.

My compost-learning experiences paralleled my winemaking experiences. Back then, having just graduated from the university, I had been conditioned to believe that the best way to learn was by using books. I had little awareness that instinct or intuition were powerful teachers. Furthermore, simple, natural processes had to be complicated with charts, graphs, measurements, devices, and all the wonderful tools of science, otherwise the processes had no validity. It was with this attitude that I set out to learn how to make wine.

The first thing I did was obtain a scientific book replete with charts, graphs, tables, and detailed step-by-step procedures. The book was titled something like "Foolproof Winemaking," and the trick, or so the author said, was simply to follow his procedures to the letter. This was no simple feat. The most difficult part of the process was acquiring the list of chemicals which the author insisted must be used in the winemaking process. After much searching and travel, I managed to get the required materials. Then I followed his instructions to the letter. This lengthy process involved boiling sugar, mixing chemicals, and following laborious procedures. To make a long story short, I succeeded in making two kinds of wine. Both tasted like crap; one was bad and the other worse, and both had to be thrown out. I was very discouraged.

Soon thereafter, a friend of mine, Bob, decided he would try his hand at winemaking. Bob asked a vineyard worker to bring him five gallons of grape juice in a five gallon glass winemaking carboy. When the grape juice arrived, Bob took one look at the heavy carboy of juice and said, " Buddy, would you mind carrying that into the basement for me?" Which the worker obligingly did.

That was it. That utterance of eleven words constituted Bob's entire effort at winemaking. Two seconds of flapping jaws was the only work he did toward making that wine. He added no sugar, no yeast, did no racking, and certainly used no chemicals. He didn't do a damn thing to that five gallons of grape juice except abandon it in his basement with an airlock on top of it. Yet, a year later that carboy yielded the best homemade wine I had ever drank. It tasted good and had a heck of a kick to it.

I admit, there was an element of luck there, but I learned an important lesson about winemaking: the basic process is very simple - start with good quality juice and keep the air out of it. That simple, natural process can be easily ruined by too many complicated procedures, and heck, all those charts and graphs took the fun out of it. Making compost, I soon learned, was the same sort of phenomenon.

In the Middle Ages, alchemists sought to change base metals, such as lead, into gold. Old German folklore tells of a tale in which a dwarf named Rumpelstiltskin had the power to spin flax straw into precious metal. Somewhere in the psyche of the western mind was a belief that a substance of little or no worth could be transmuted by a miraculous process into something of priceless value. Our ancestors were right, but they were barking up the wrong tree. The miraculous process of composting will transmute humanure into humus. In this way, potentially dangerous waste materials become soil additives vital for human life.

Our ancestors didn't understand that the key to this alchemy was right at their fingertips. Had they better known and understood natural processes they could have provided themselves with a wealth of soil fertility and saved themselves the tremendous suffering caused by diseases originating from fecal contamination of the environment. For some reason, they believed that gold embodied value, and in pursuit of glittering riches they neglected the things of real value: health, vitality, self-sufficiency, and sustainability.

Our ancestors had little understanding of a vast, invisible world which surrounded them, a world of countless creatures so small as to be quite beyond the range of human sight. And yet, some of those microscopic creatures were already doing work for humanity in the production of foods such as beer, wine, cheese, or bread. Although yeasts have been used by people for centuries, bacteria have only become harnessed by western humanity in recent times. Composting is one means by which the power of microorganisms can be utilized in a big way for the betterment of humankind. Unfortunately, our ancestors didn't understand the role of microorganisms in the decomposition of organic matter, nor the efficacy of microscopic life in converting humanure, food scraps, and plant residues into soil. They didn't understand compost.

The composting of organic materials requires armies of bacteria. This microscopic force works so vigorously that it heats the material to temperatures hotter than are normally found in nature. Other micro and macro organisms such as fungi and insects help in the composting process, too. When the compost cools down, earthworms often move in and eat their fill of delicacies, their excreta becoming a further refinement of the compost.

Successful composting requires the maintenance of an environment in which bacteria and fungi can thrive. This is also true for wine, except the microorganisms are yeast, not bacteria. Same for bread (yeast), beer (yeast), yogurt (bacteria), sauerkraut (bacteria), and cheese (bacteria); all of these things require the cultivation of microorganisms which will do the desired work. All of these things involve simple processes which, once you know the basic principles, are easy to carry out successfully. Sometimes bread doesn't rise, sometimes yogurt turns out watery, sometimes compost doesn't seem to turn out right. When this happens, a simple change of procedure will rectify the matter. Once you get the hang of it, you'd think even a chimpanzee could be trained to make compost.

Often, in our household, we have yogurt being made by billions of hard-working bacteria in a few quart mason jars beside the cookstove. At the same time, millions of yeast cells are cheerfully brewing beer in carboys in the back pantry, while millions more yeasts are happily brewing wine beside the beer. Sauerkraut is blithely fermenting in a crock behind the stove; bread is rising on the kitchen counter; and fungi are tirelessly forcing their fruits from oak logs on the sunporch. And then there's the compost pile. At times like these, I feel like a slave driver. But the workers never complain. Those little fellas work day and night, and they do a real nice job.

Organic refuse is stored solar energy. Every apple core or potato peel holds a tiny amount of stored energy, just like a piece of firewood, which is converted into useable plant food by the compost pile. Perhaps S. Sides of the Mother Earth News states it more succinctly: " Plants convert solar energy into food for animals (ourselves included). Then the [refuse] from these animals along with dead plant and animal bodies, ?lie down in the dung heap,' are composted, and ?rise again in the corn.' This cycle of light is the central reason why composting is such an important link in organic food production. It returns solar energy to the soil. In this context such common compost ingredients as onion skins, hair trimmings, eggshells, vegetable parings, and even burnt toast are no longer seen as garbage, but as sunlight on the move from one form to another."

The organic material used to make compost could be considered anything on the Earth's surface that had been alive, or from a living thing, such as manure, plants, leaves, sawdust, peat, straw, grass clippings, food scraps, and urine. A rule of thumb is that anything that will rot will compost, including such things as cotton clothing, wool rugs, rags, paper, animal carcasses, junk mail, and cardboard.

To compost means to convert organic material ultimately into soil or, more accurately, humus. Humus is a brown or black substance resulting from the decay of organic animal or vegetable refuse. It is a stable material that does not attract insects or nuisance animals. It can be handled and stored if necessary with no problem, and it is beneficial to the growth of plants. Humus holds moisture, and therefore increases the soil's capacity to absorb and hold water. Compost is said to hold nine times its weight in water (900%), as compared to sand which only holds 2%, and clay 20%.

Compost also adds slow-release nutrients essential for plant growth, creates air spaces in soil, helps balance the soil pH, darkens the soil (thereby helping it absorb heat), and supports microbial populations that add life to the soil. Nutrients such as nitrogen in compost are slowly released throughout the growing season, making them less susceptible to loss by leaching than the more soluble chemical fertilizers. Organic matter from compost enables the soil to immobilize and degrade pesticides, nitrates, phosphorous, and other things that can become pollutants. Compost binds pollutants in soil systems, reducing their leachability and absorption by plants.

The building of topsoil by Mother Nature is a centuries long process. Adding compost to soil will help to quickly restore fertility that might otherwise take nature hundreds of years to replace. We humans deplete our soils in relatively short periods of time. By composting our organic refuse and returning it to the land, we can restore that fertility also in relatively short periods of time.

Fertile soil yields food that promotes good health. One group of people, the Hunzas of northern India, has been studied to a great extent. One man who studied them extensively, Sir Albert Howard, stated, " When the health and physique of the various northern Indian races were studied in detail the best were those of the Hunzas, a hardy, agile, and vigorous people, living in one of the high mountain valleys of the Gilgit Agency . . . There is little or no difference between the kinds of food eaten by these hillmen and by the rest of northern India. There is, however, a great difference in the way these foods are grown . . . [T]he very greatest care is taken to return to the soil all human, animal and vegetable [refuse] after being first composted together. Land is limited: upon the way it is looked after, life depends."

There are several reasons for piling the composting material. A pile keeps the material from drying out or cooling down prematurely. A level of moisture (50-60%) is necessary for the microorganisms to work happily. A vertical stack prevents leaching and waterlogging, and holds heat in the pile. Vertical walls around a pile, especially if they're made of wood, or bales of straw, keep the wind off and will prevent one side of the pile (the windward side) from cooling down prematurely.

A neat, contained pile looks better. It looks like you know what you're doing, instead of looking like a garbage dump. A constructed compost bin also helps to keep out nuisance animals such as dogs.

A pile makes it easier to layer or cover the compost. When a smelly deposit is added to the top, it's a good idea to cover the raw refuse with clean organic material in order to eliminate unpleasant odors and to trap necessary oxygen in the pile. Therefore, if you're going to make compost, don't just fling it out in your yard in a heap. Construct a nice bin and do it right. That bin doesn't have to cost money; it can be made from recycled wood or cement blocks. Wood (not pressure-treated) may be preferable as it will insulate the pile and prevent heat loss and frost penetration. A compost bin doesn't have to be complicated in any way. It doesn't require electricity, technology, gimmicks, or doodads. You don't need shredders, choppers, grinders, or any machines whatsoever.

Compost pits are more likely to be used in dry, arid, or cool climates where conservation of moisture and temperature is imperative. The main disadvantage of pits is that they can become waterlogged in the event of an unexpected cloudburst, and excessive water will rob the pile of oxygen, a critical element in the process of decomposition by aerobic microorganisms. Therefore, when pits are used, a roof over them may be an advantage, and air channels may be necessary to allow oxygen to enter the compost.

Compost must be kept moist. A dry pile will not work. When people who don't understand compost try to picture a humanure compost pile in someone's backyard, they imagine a giant heap of crap, draining all manner of noxious, smelly liquids out the bottom of the compost bin, and leaching into the groundwater. However, a compost pile is not a pile of garbage or waste. It's a living, breathing mass, a biological sponge which requires quite a bit of moisture. It's not likely to create a leaching problem unless subjected to very heavy rains while uncovered.

Why does compost require moisture? For one thing, composted materials shrink incredibly (40-80%), mostly because of water loss. Compost can undergo considerable drying when wet materials are composted. An initial moisture content of 65% can dwindle down to 20 to 30% in only a week, according to some researchers. It is more likely that one will have to add moisture to their compost than have to deal with excess moisture leaching from it.

The amount of moisture a compost pile receives or needs depends on the materials put into the pile and on the location of the pile. In Pennsylvania, there are about 36 inches (about one meter) of rainfall per year, and compost only needs watering during an unusual drought. According to Sir Albert Howard, watering a compost pile in England (where the annual rainfall is 24 inches) is also unnecessary. Nevertheless, the water required for compost-making may be around 200 to 300 gallons for each cubic yard of finished compost. This moisture requirement will be met when human urine is used in humanure compost and the top of the pile is open and receiving adequate rainfall. Additional water comes from moist organic materials such as food scraps. If adequate rainfall is not available and the contents of the pile are not moist, watering will be necessary to produce a moisture content equivalent to a squeezed-out sponge. Graywater from household drains or collected rainwater would suffice for this purpose.

We want to cultivate aerobic bacteria in the compost pile to ensure thermophilic decomposition. This is done by adding bulky materials to the compost pile in order to trap interstitial air spaces. Aerobic bacteria will suffer from a lack of oxygen if drowned in liquid, which is a common problem with commercial and home made composting toilets when improperly managed.

Bacterial decomposition can also take place anaerobically, but this is a slower, cooler process, which can, quite frankly, stink. Anaerobic odors can smell like rotten eggs (caused by hydrogen sulfide), sour milk (caused by butyric acids), vinegar (acetic acids), vomit (valeic acids), and putrification (alcohols and phenolic compounds). Obviously, we want to avoid such odors by maintaining an aerobic compost pile.

Figure 3.2: The author probing a humanure compost pile in late winter. This compost had not yet become thermophilically active. Of the two thermometers, one has a long probe and the other
a short one. PHOTO BY JEANINE JENKINS

Good, healthy, aerobic compost need not offend one's sense of smell. However, in order for this to be true, a simple rule must be followed: anything added to the compost that smells bad must be covered with a clean, organic material. This means you must cover the deposits in your compost toilet and on your compost pile. When you defecate or urinate in your toilet, cover it. Use sawdust, use peat, use clean soil, use leaves, but keep it covered. Then there will be no odor. When you deposit smelly manure on your compost pile, cover it. Use weeds, use straw, use hay, whatever you can get your hands on (especially bulky material which will trap oxygen in the compost), but keep it covered. That's the simple secret to the odor issue.

Dehydration will cause the compost microorganisms to stop working. So will freezing. Compost piles will not work if frozen, which often occurs during the cold winters of the north. However, don't despair, the microorganisms will wait until the temperature rises and then they'll thaw out and, once again, work feverishly. You can continue to add to an outdoor compost pile all winter, even when the pile is frozen solid as a rock. The freezing stage helps to destroy some potential pathogens and, after the thaw, the pile works up a steam as if nothing happened.

A good carbon-nitrogen balance (a good blend of materials) is required for a nice, hot compost pile. Since most of the materials commonly added to a compost pile are very high in carbon, this means that a source of nitrogen must be incorporated into the blend of composting ingredients. This isn't as difficult as it may seem. You can carry bundles of weeds to your compost pile, add hay, straw, leaves, and garbage, but you'll still need one thing: nitrogen. Of course the solution is simple - add manure. Where can you get manure? From an animal. Where can you find an animal? Look in a mirror.