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EAP Publication - 57

Composting for Farm and Garden

Part I: The Whys and Wherefores

by Professor Stuart B. Hill Department of Entomology

Answering the question, "how should I make compost?" is rather like answering the question, "how can I bake a cake?" It depends on what your objectives are, what materials and equipment you have to work with, and how much effort you are willing to put in.

The reasons for composting have been twofold. Most of the estimated 10 to 100 million tons of compost produced annually is made to get rid of organic wastes with their associated space requirements, odours, and contained plant or animal pathogens. The more positive objective, which is usually the one mentioned by backyard gardeners, is to build up or maintain the fertility of the soil. Actually, composting enables us to achieve both these objectives, but more than that it enables us to achieve them in a way that can be part of a permanent survival strategy for man. Let me explain. Homo sapiens like all other species are subject to the laws of nature whether we like it or not. If we want our species to survive, which I assume most of us do, it is vital that we become aware of these laws. Here are two of the laws, relevant to this topic, that I have become aware of:

1. SURVIVAL IS DEPENDENT UPON NEEDS AND AVAILABILITY OF WHAT IS NEEDED

It follows from this that we must sort out what our real needs are. We could say that one primary need is to be happy; to be happy we need to be healthy and to be healthy we must have an adequate supply of suitable, high quality food; to ensure this we must only employ food production strategies that utilize types and amounts of materials that we can go on using for ever, i.e., we must establish as near permanent strategies as possible.

Most plants need nutrients such as nitrogen, phosphorus, and potassium, and in nature they usually get them via the decomposition of organic materials, such as fallen leaves, which they produce themselves. The most stable communities of plants are also the most complex, that is, being made up of a large number of species. Within such a complex community many mutually beneficial relationships exist. For example, plants produce organic matter, which the decomposers utilize as their source of nutrients and in so doing they provide the inorganic and simple organic nutrients required by plants.

In contrast, in conventional agriculture, which is usually concerned with simple communities we take non-renewable fossil fuels and mineral deposits, synthesize inorganic or simple organic plant nutrients and apply these to the soil for the plant. In doing this we are, as it were, putting the decomposers out of business and, at the same time, becoming "addicted" to certain limited resources. It seems to me that we would better ensure our survival by directing our efforts to understanding how to cooperate with the decomposers, who, after all, are the experts at supplying nutrients to plants. They have been doing it for millions of years, whereas we are mere novices as seen by the frequency with which our efforts are ineffective or even harmful, e. g., contamination of lake, river, and well water with nitrogen fertilizers, increased susceptibility of crops to disease and pest attack, contamination of vegetables with toxic levels of nitrate. Adding compost to soil represents one attempt to cooperate with the decomposers and enable them to supply nutrients to our crops. It also improves soil aeration, drainage, moisture and plant nutrient retention, soil stability, and it reduces the energy required for tillage. Compost can also lead to increased resistance in plants to pathogens and pests. What NPK fertilizer can claim to do all these things?

2. IN NATURE RELATIONSHIPS ARE CYCLICAL AND ALL CYCLES ARE INTERRELATED

I have already referred to the cyclical relationship between decomposers and plants. We should try to tune in to this relationship rather than ignore it, as we presently do, i.e., we take organic materials from rural areas in the form of food, fibre, and wood and deposit them in cities; we then take the consumption and by-product wastes resulting from their use and burn them, causing air pollution, dump them in the river, causing water pollution, or dig them into nonproductive land (landfill), causing soil pollution. Rather we should be keeping these "natural" organic materials separate from the "synthetic" organic and non-organic materials (plastic, metal, glass) and recycle them back to the environment they came from. By doing this we would be forced to take a more realistic view of the economics of our present lifestyle. We would see, for example, that the cost of recycling citrus wastes back to Florida or California is much greater than recycling the waste from green peppers or red cabbage (equally good sources of vitamin C) back to our own backyards or to the local market garden; yet our present agricultural policy supports a "health strategy" that encourages the use of citrus as our source of vitamin C.

You might wonder why we cannot simply return our organic wastes to productive land without composting it. Well there are several reasons. These wastes usually contain one or more of the following things:

1. plant pathogens

2. plant parasites

3. other plant pests, e.g., nematodes and insects

4. animal pathogens

5. animal parasites

6. other pest and nuisance organisms e.g., maggots of houseflies

7. seeds, including weed seeds

8. animal matter (attracts rats, dogs, etc.)

9. non-degradable materials, e.g., glass, metal, plastic

10. toxic chemicals, e.g., pesticides antibiotics, heavy metals dyes

11. already putrefying materials that are giving off bad odours.

In addition, household refuse usually has a very high carbon to nitrogen ratio (C/N=150:1 to 50:1) because of its high paper content. This would result in a decreased availability of nitrogen to the plant if applied directly to land. In contrast, sewage sludge and farm and garden wastes, such as animal manures, grass clippings and kitchen wastes, usually have a fairly low C/N ratio (50:1 to 5:1). One approach has been to mix these two different types of materials (household refuse and sewage sludge or manure) to provide an optimum starting C/N ratio for composting, e.g., 35:1 to 30:1.

During the process of composting carbon is lost as the gas carbon dioxide; nitrogen should remain the same or even increase as a result of the fixation of nitrogen from the atmosphere by certain microorganisms. The resultant compost ideally has a C/N ratio of 12:1 to 10:1.

Composting provides the best means to eliminate problems that may result from the presence of the materials listed above. If carried out properly, pathogens, parasites, other pest organisms, and seeds are killed (by heat, predation, and antibiotics), the presence of animal matter provides no problems if the area is protected from vermin, non-degradable materials can be removed, before or after composting, for recycling, toxic chemicals are broken down or tied-up during composting by the formation of complex compounds or by adsorption, and smells may be eliminated by ensuring an adequate supply of oxygen and by controlling the pH (acidity/alkalinity) of the material. Thus, the compost heap provides a means of filtering out undesirable materials and of improving the fertilizer value of organic wastes.

Composting is basically a controlled humus producing process, and it is largely the humus fraction of compost that directly or indirectly bestows all the benefits on soil mentioned earlier. While the data presently available are inadequate, I suspect that if we took a particular amount of raw organic matter (e.g., a green manure) and ploughed it into the soil we would end up with less soil humus than if we composted it and ploughed in the compost, this being because it is easier to manage a compost heap than soil for humus production. In conventional agriculture the management of soil for humus production conflicts with its management for plant production.

The following two statements are frequently made regarding the feasibility of maintaining soil fertiIity by composting.

1. "Surely it can't be done economically on a large scale." Well, one composter in Texas (where I understand everything is bigger and better) is supplying compost to farms totaling 1/4 million acres and he sees no reason why in the future he could not meet the needs of 10 million acres and decrease their fertilizer bill at the same time.

2. "Surely there isn't enough organic matter to fertilize our soils with compost." This position is frequently held by those who measure the fertilizer value of compost in terms of its NPK. Compost, however, often has relatively little NPK and yet has an enormously beneficial effect.

This is largely because of its direct and indirect effects on the rate of mineralization and immobilization of plant nutrients. The major inputs required for this process are mineral matter (e.g., the earth's crust - hardly a limiting factor) and organic matter, with its contained flora and fauna. In temperate countries there is unlikely to be a shortage of organic matter as their low average annual temperatures favour plant growth above decomposition, i.e., plant matter is produced faster than it can be broken down and as a consequence it has the potential to accumulate. It must also be remembered that some of the nitrogen in the organic wastes has come from the air by nitrogen fixation rather than from the soil so we should be able to add more nitrogen to the soil than was there in the first place; and in addition the composting operation can be managed to bring about nitrogen fixation within the heap (particularly by adding phosphorus to it as rock phosphate, bone meal, hoof and horn, fruit wastes or activated sewage sludge). In the tropics the opposite is usually the case, i.e., decomposition proceeds faster than plant growth (Mohr and Van Barren 1972); however, Sir Alberta Howard (1943), the father of composting, has shown that compost improves the "health" of the soil, plants, and animals there also.

Let us now look at the ways of composting on the farm and in the garden. Poincelot (1972), Gray et al. (1971-7972) and Golueke (1972) have provided the best short reviews of the process and these should be consulted for further details. Current articles appear in "Compost Science ", " Bio-Dynamics ", "Acres, U.S.A." and "Organic Gardening and Farming". Canadian experiences are recorded by Bell and Pos (1973), Grussendorf (1970, 1971) and MacLean and Hore (1974). In addition, an annotated bibliography of composting references has been prepared on campus and is available for the cost of copying it (Merrill and Hill 1975).

Composting for Farm and Garden

Part Il: How To Do It

For Part II of "Composting for Farm and Garden" Professor Hill was interviewed by Hazel M. Clarke of the Journal. Questions will appear in italics. Both Professor Hill and the Journal would like to thank Graham Lowe of the Soils and Land Resources section of the Department of Renewable Resources and Spencer Cheshire of Smithville, Ontario, for their valuable comments on this article.

Would you summarize Part I by saying what you consider the objectives of a fertilization program should be?

Professor Hill: Ideally the program should satisfy the following criteria:

For socio-economic survival (applies more to farm than garden):

1. be economically feasible;

2. be socially acceptable, e.g., to farm hands and neighbours;

For biological survival (applies to all):

3. require minimal energy and other non-renewable resource inputs, e.g., minimal use of machinery and manufactured products;

4. should cooperate with ecological cycles and processes, e.g., be based on the return of organic wastes to soil and utilize soil decomposers for their break down;

5. should not overload any systems or lead to pollution of water, air, soil, or food products;

6. the plant nutrients should be released to the plants as they require them;

7. should lead to the build-up and maintenance of soil structure.

What does a farmer need to get started?

Professor Hill: Basically three things:

1. a good supply of organic matter; ideally a mixture of animal and vegetable wastes;

2. a power take-off tractor with a front-end loader and a power take-off manure spreader; a gardener just needs a fork, spade, and wheelbarrow or cart. Shredders are useful but not essential. Push lawnmovers and corn cutters can be modified to make hand operated shredders;

3. but most important of all an experimental, adaptable approach to farming or gardening.

What should he do first?

Professor Hill: I would suggest that he set aside a representative part of his land, perhaps his smallest field, to test compost on. It is very important that the test runs for four or five years as the benefits of compost are cumulative and may not be fully evident in the first year. Ideally he should aim to add 10 to 20 tons/acre (app. 1 Ib/sq. ft.) in the first year. This may be reduced to as little as one ton per acre as the soil improves. Some farmers in Texas who have done this maintain that they have reduced their fertilizer costs from between $45 and $75 per acre using NPK to $25 per acre using compost. Most farmers using compost disc it into the top six inches of soil in the spring or fall.

Most farmers make compost in windrows, six feet wide at the base with steeply sloping sides, three to five feet high with a central depression along the top to catch moisture, and as long as you like. The windrows should be located on well-drained soil near the sources of organic wastes.

Should gardeners build the same type of heap?

Professor Hill: Gardeners usually do not compost in windrows as they rarely have enough materials to make a large enough heap. If the heap is not large enough, it will not heat up and weed seeds, disease organisms, and pests may not be killed. Also a small, exposed heap will tend to dry out and will be prone to disturbance by animals. These problems may be overcome by constructing a wooden composting box. Wire mesh enclosures are only suitable if they are lined with cardboard; otherwise they will not hold the heat. The most practical design consists of two 3 or 4 ft. square bottomless compartments, arranged side by side, with the fronts open so that boards can be slid in as the organic waste accumulates (a 4 ft. x 4 ft. x 4 ft. box will hold a ton of compost, enough for over 500 sq. yds. of garden if put on to a depth of 2 to 3 inches). If creosoted and painted with black bituminous paint, these "New Zealand" composting boxes will last 20 or more years. They should be located:

1. where it will enhance rather than mar the appearance of the garden and where it will not annoy the neighbours;

2. where it will be most convenient to take organic wastes to (including loads of animal manure and winter kitchen waste) and collect compost from

3. in a well-drained site, sheltered from high winds and hot sun, ideally sheltered by an elderberry bush, as most species of earthworm favour their leaves and will consequently be plentiful in the surrounding soil!

Composts should usually not be built on concrete or in pits as the former will impede drainage and aeration and the latter will tend to fill up with water in the winter and will also suffer from a shortage of air.

The organic waste is collected initially in the first compartment of the composting box until there is sufficient material to build the "compost heap proper" in the second compartment. Most "compost heaps proper" are built in autumn when there is a flood of materials in the form of leaves and end-offseason refuse. If all goes well, the resultant compost will be ready for distribution in spring.

What materials may be put into a compost heap?

Professor Hill: While organic matter is the main ingredient, many other things may be added --this is where the value of an "experimental" mind comes in. Here is a comprehensive list:

Organic matter: animal wastes, especially manures (high N); plant wastes, e.g., green manures, straw, hay, grass clippings, weeds, leaves, crop wastes, food processing and kitchen wastes, seaweed (low to high N): wood and paper wastes (low N); urban wastes, e.g., sewage (moderately high N), garbage (low N); partially decomposed materials, e.g., peat moss, leaf mould (low N) rotted manures (high N).

Organisms: rich fertile soil (important primary source of decomposers, nitrogen fixers and trace elements); commercially available cultures of decomposers and nitrogen fixers, e.g., the B-D Starter (available from The Pfeiffer Foundation, Inc., Threefold Farm, Spring Valley, New York, 10977); manure worms, e.g., the worms usually found in piles of rotting manure.

Materials to supplement plant nutrients (roughly in decreasing order as percentage by weight)

Nitrogen:

  • feathers
  • blood meal
  • wool and felt wastes
  • fish and marine products
  • tankage
  • gluten meal
  • tea grounds
  • peanut shells
  • tobacco stems
  • raw bone meal
  • soybean hay
  • animal wastes
  • urine
  • Potassium:

  • wood and other plant ash
  • green sand
  • tobacco stems
  • granite dust
  • water lily stems
  • millet straw
  • urine
  • Phosphorus:

  • rock phosphate
  • bone meal
  • fish & marine products
  • tankage
  • activated sewage sludge
  • blood meal
  • wool wastes
  • plant ash
  • Trace Minerals:

  • certain rock dusts
  • glacial deposits
  • marine products
  • sewage and urban wastes
  • certain "accumulator" plants (see Rateaver & Rateaver, 1973)
  • Materials to reduce acidity:

    dolomitic limestone (slower acting than lime so less chance of nitrogen loss as ammonia), wood ash.

    Materials to stimulate decomposers:

    Nitrogen sources

    see above

    Fermented plant materials:

    (added by big-dynamic composter --for details write the Secretary of the Bio-Dynamic Farming & Gardening Association in Canada John Rohlman, R.R. 1, Terra Cotta Ontario LOP 1NO see also Bruce 1967 for an alternative approach) Oak bark, valerian, stinging nettle, and the flowers of dandelion chamomile and yarrow.

    Seaweed extracts: contain cytokinin plant hormones.

    Other important things that must be regulated in the heap are moisture, air, and warmth. Let me emphasize that I have included this long list for those who want to experiment; the only vital components are organic matter and decomposers. The other materials speed up the process or vary the properties of the end product.

    How is the heap constructed?

    Professor Hill: If using a compost box, it is best to raise the heap slightly off the ground so that air may enter from below. This may be accomplished by placing several rows of bricks, one inch apart, directly on the soil or by laying a few branches on the ground. The heap is then constructed by starting with a layer of coarse material, which will prevent the finer organic matter from falling in between the bricks. Then add a 5- to 8-inch layer of the organic waste that has been collected in the first box. In order for it to decompose, it will usually need inoculating with suitable microbes and they will require a supply of available nitrogen. The microbes can be introduced by sprinkling some finished compost or fertile soil over the layer; and the nitrogen by adding a 4/2 to 2-inch layer of nitrogen-rich material (see the list above). Extra phosphorous and potassium can be provided, if required, by sprinkling a handful of any of the materials listed above. To prevent the heap from becoming too acid, a handful of crushed dolomitic limestone can be added to each layer although this is not usually necessary and can lead to a loss of nitrogen. Watering the layers with human or animal urine diluted two or three times with water will not only moisten the material, but will supply it with nitrogen and potassium. This is particularly useful if you are trying to compost leaves as they tend to be very low in nitrogen. Further layers are built up in this way until the compartment is filled. It should then be lightly patted down to bring the various components into closer contact and to prevent the surface from blowing away.

    Ventilation of the heap will be enhanced by piercing it in several places with a three-inch diameter stake.

    I was rather surprised that you mentioned using human urine; isn't there a danger of diseases being spread by doing this?

    Professor Hill: No. Urine comes from the kidney, the body's filtration system; so unless one is suffering from a bladder infection it should be fairly sterile. It is funny how many people are anxious to contribute towards recycling by collecting glass or newspaper, which is of questionable value as the process utilizes considerable amounts of energy, but when it comes to "real" recycling, such as we are talking about now, they shy away. Utilizing our urine as fertilizer not only aids composting but saves the vast amounts of water used to flush this valuable fertilizer into our waterways where it can contribute to pollution by helping speed up eutrophication.

    How should the farmer set about constructing his windrows? Isn't it going to require a lot of extra labour?

    Professor Hill: Like all new tasks composting may require some extra labour the first time around but it soon becomes part of the annual routine. Actually the heaviest part of the work is the initial handling of the raw manure, and that is something that has to be done anyway. First the manure spreader is loaded with organic wastes by means of the front-end loader. Periodically a shovelful of fertile soil or mature compost (up to 10 per cent of the total) should be thrown over the compost material to inoculate it with decomposers. Other supplements may be added at this stage, if desired. If the material is dry it should be sprayed with water or urine so that it has the feeling of a squeezed out sponge. The spreader is then drawn to the site chosen for the heap and the machine put into operation. A hood should be built over the beaters so that the compost material does not spread but comes down on the ground neatly. A removable hood can be made from lumber or from a three-foot iron culvert split in half lengthwise. The first section of the heap is built up to at least three feet high; the spreader is then moved forwards about two feet and a second section built up. Each new load must be backed up against the end of the windrow and the process continued until the pile is completed. In throwing out the material it is shredded and aerated. If you wish to inoculate the material with a commercial culture of decomposers you can do it by spraying into the material as it comes off the beaters, by means of a knapsack sprayer. The compost material retains its loose structure only if it contains a good proportion of straw or other coarse material. If it becomes compacted, anaerobic conditions will develop and it will start to smell. It is a good idea to cover the entire heap with a two-inch skin of top-soil although this is not essential. As with the garden compost ventilation should be provided by piercing the heap at three feet intervals with a three inch diameter stake. If it is very rainy or if winter is approaching it is best to cover the heap and insulate it. This can be done with a sheet of 10 feet wide black polythene (six microns thick). A thick layer of straw, hay, or leaves is spread over this, then another sheet of polythene, and another layer of straw. This keeps the heap warm so that it will be ready for distribution in the spring. Alternatively, if it is not wet or not getting cold the heap should be allowed to heat up (to 55C) and then cool down. This usually takes three to four weeks; then the heap is turned by means of a front-end loader. Marvin Urbancyk, of Texas, has designed a machine that sells for a little over $30,000 that will turn 500 to 600 tons per hour (see Acres, U.S.A. 4(5): 16-17, April 1975), but 1 guess it will be some time before our readers get that involved with compost. Generally the more often the heap is turned the faster it breaks down.

    You mentioned earlier about adding manure worms. When would you do this?

    Professor Hill: Some farmers keep a culture of manure worms and add a handful every 10 yards or so to the edge of the heap after the last turn.

    What if our readers do what you say and the heap does not heat up or come spring and it still has not composted? What could have gone wrong?

    Professor Hill: There are several factors that can affect the success of the process and the rate of decomposition, and these should be considered if things go wrong. However, if the heap doesn't heat up or if it takes a little longer than is expected only time is lost; the compost will still be a valuable soil amendment.

    These factors are:

    1. Size of fragments or organic waste. The smaller they are the faster the decomposition. For windrows 1:5- to 3-inch fragments are optimal. Actually, shredding and attention to the various other limiting factors can result in compost being formed in as little as 14 days.

    2. Degree of mixing and variety of components in the heap. The greater the variety and the more thoroughly they are mixed, the faster the decomposition. This can be accomplished either when constructing the heap or by turning it periodically. With a compost box this can be done by transferring the heap from one compartment to the next.

    3. Availability of air, moisture, and nutrients for the decomposers. If the heap is too loose the circulating air will cool it; and if it is too compact the lack of air will cause it to become anaerobic and it will start to smell. The heap should be kept moist at all times, but not soggy. A moisture content of 50 to 60 per cent is optimal, i.e., if you squeeze the compost in your hand, it should feel damp, but water should not drip out of it. it is best to protect the heap from heavy rain by covering it in some way. Generally if the heap does not heat up and moisture and air are not a problem, then it is because of a lack of nitrogen and some must be added in one of the forms listed earlier. It should be remembered that certain materials take longer to compost than others. The brown leaves collected in autumn usually take much longer than grass clippings, green garden residues and kitchen wastes. Consequently, if speed is important, leaves should be broken up as much as possible and mixed with fast decomposing wastes. Alternatively they could be kept separate and composted in a two-year heap.

    4. Temperature of the heap. Often small heaps do not heat up because they lose heat faster than it is being generated. It is best to insulate small heaps and heaps that will be composting through the winter. On the other hand it is wise to prevent the heap from going over 55C as above this it tends to become alkaline and nitrogen may be lost as ammonia. Overheating can be prevented by adding soil or material with a high C:N ratio such as leaves up to 10 per cent by volume. Temperature is so important that it is used to refer to the various stages in composting, i.e., mesophilic, thermophilic, cooling down, and maturing. Different decomposer microorganisms are active at each of these stages so there is a succession of microbial activity, each microbe being limited by the temperature and the food or compost material available.

    How do you know when the compost is ready for distribution?

    Professor Hill: The compost maybe regarded as finished when it is fine and crumbly to touch and dark in colour. This usually takes two to eight months. It can be added directly to the soil or, if it is to be used as a potting mixture or for application to lawns, it is sieved first.

    Perhaps you would wind up by summarizing the benefits of compost.

    Professor Hill: Let me quote from a flier describing a commercially available compost. When used "you secure vigorous, healthy crops of high yield. The soil warms faster, enables you to work the ground and makes earlier planting possible . . . quicker emergence, maturity, and harvest. The soil becomes Friable taking water well, and holding it better, thus reducing irrigation requirements by as much as one third. Weeds become easier to control and diseases and insects, nature's eliminators of the unfit, become less of a problem. Fewer trips over the field are required to prepare for planting"; or as Tusser put it in 1557, "One aker well compost is worth akers three . . ." All this plus the knowledge that by going the compost route you will not be unnecessarily using up our diminishing energy reserves, not adding to environmental pollution, and you will be cooperating with the ecological cycles, providing your plants with nutrients as they need them, and building up your soil. Composting provides a way to make peace with your land.

    Bibliography

    ACRES, U.S.A.: A VOICE FOR ECOAGRICULTURE. 1971 - [12/yr.). 10227 East 61st St., Raytown. Mo. 64133.

    Bell, R. 5. and J. Pos. 19,3. HIGHRATE COMPOSTING OF MUNICIPAL REFUSE AND POULTRY MANURE. Can. Agric. Eng. 15(1): 49-53. 6 refs.

    BIO-DYNAMICS. 1941 (4/yr.). Biodynamic Farming & Gardening Assoc., inc., 308 East Adam St., Springfield, 111. 62701.

    Bruce, M. 1967. COMMON-SENSE COMPOST MAKING BY THE QUICK RETURN METHOD. 96 pp. Faber & Faber, Lond. 19 refs.

    COMPOST SCIENCE: JOURNAL OF WASTE RECYCLING. 1959 - t6/yr). Rodale Press, Inc.. Emmaus, Pa. 18049.

    Golueke, C. G. 1972. COMPOSTING: A STUDY OF THE PROCESSES AND ITS PRINCIPLES. 110 pp. Rodale press, Inc., Emmaus, Pa. 62 refs.

    Gray K. R., K. Sherman and A. J. Biddlestone. 1971. A REVIEW OF COMPOSTING--PART 1. Process Biochem. 6(6): 32-36. 41 refs.

    Gray, K. R., K. Sherman and A. J. Biddlestone. 1971. A REVIEW OF COMPOSTING -- PART 2. Process Biochem. 6(10): 22-28. 56 refs.

    Gray, K. R. A. J. Biddlestone and R. Clark. 19i3. REVIEW OF COMPOSTING --PART 3: Process Biochem. 8(11): 73-78. 71 refs.

    Grussendorf, O. W. 1970. MECHANIZED COMPOST MAKING-- FARM SCALE. Land Bull. 147, 1-3. No refs.

    Grussendorf, O. W. 1971. HOME GARDENING WITHOUT CHEMICALS IV. PRACTICAL COMPOST MAKING FOR THE HOME GARDENER. Land Bull. 166, 14. No refs.

    Howard, Sir Albert. 1943. AN AGRICULTURAL TESTAMENT. 252 pp. Rodale Press, Inc., Emmaus, Pa. Refs after each chapter.

    MacLean, A. J. and F. R. Hore. 1974. MANURES AND COMPOST. Agric. Canada Publ. 868: 15 pp No refs.

    Merrill, R. and S. B. Hill. 1975. COMPOSTING (AND HUMAN WASTE Reprinted from THE MACDONALD JOURNAL, November 1975 PRINTED IN CANADA SYSTEMS). 5 pp. 50 refs.

    Mohr. E. C. J. and F. A. van Baren. 1972. TROPICAL SOILS. 3rd edn. N. V. Uitgeverij W. van Hoeve, The Hague.

    ORGANIC GARDENING AND FARMING. 1942 - (12/yr.). Rodale Press, Inc., Emmaus, Pa. 18049.

    Poincelot, R P. 1972. THE BIOCHEMISTRY AND METHODOLOGY OF COMPOSTING. 38 pp. Bull. 727, Conn. Agric. Expt. Sta. 169 refs. (Currently being revised).

    Rateaver, B. and G. Rateaver. 1973. THE ORGANIC METHOD PRIMER. 257 pp. B. Rateaver, Pauma Valley, Ca.

    Copyright 1975 Ecological Agriculture Projects


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