By Eliot Coleman
The industrial production system of modern agriculture is not without problems. The most pervasive of these are soil erosion, pollution from pesticides and fertilizers, increasing costs of inputs, declining soil productivity, resistant pests and diseases, and the economic loss consequent on all of the above.
The 1980 USDA Report and Recommendations on Organic Farming concluded that the alternative production technologies employed in “organic” agriculture had the demonstrated potential to free farmers from most if not all of these problems. Although the report was widely distributed, there has been no noticeable rush of farmers shifting from a chemical/industrial to biological/ecological agriculture. I believe the fundamental reasons for this are not always well understood.
There are impediments to the general acceptance of all new ideas. Some are easily dealt with by communication and education. Others are more substantive, deep-seated, and harder to change. The more easily overcome impediments to adoption of an ecological agriculture we will call the definitional, attitudinal, scientific, and economic. These can hopefully be dealt with through reason and common sense.
It is on a deeper level, the philosophical and psychological essence of our conceptual thinking patterns, that the difficulty arises. It is here that the major change must occur. On this substantive level the key impediment to change is the dichotomy that exists between a symptom treatment mentality, so much a part of our everyday existence, and a cause correction approach, inherent in an ecological system of agriculture. Each of these impediments will be discussed in turn, but special attention will be paid to the philosophical and psychological block.
Precise definition of a movement is frequently an elusive target. The alternative agriculture movement is no exception. Even among its followers the difficulty of arriving at a definition is often, to rephrase the old theological polemic, like trying to decide how many beneficial bacteria can dance on the tines of a manure fork. Thus the movement is susceptible to misrepresentation not only by its detractors through misunderstanding or intentional obfuscation, but also by its adherents because of undocumented claims or excessive zeal.
A further problem is that many articles misrepresent alternative agriculture as a lifestyle rather than as a branch of agricultural science. The press has tended to focus on the non-agricultural crusades of certain “organic” adherents. That is not agriculture. A very significant distinction must be drawn between farming and something called the “organic way of life.” Association with an unwinnable socio-philosophical debate should not condemn the agricultural value of the practices, which constitute the basis of alternative agriculture.
The common definitions for alternative agriculture are inadequate. Most attempts are either couched in negative terms –“don’t use this,” “don’t do that” – or consist of extensive lists specifying what can or should be used (ie. organic manures, dried blood, bone meal) in place of the prohibited products. This substitution approach, to give it a name, may reflect popular impressions regarding the farming techniques but has little connection with knowledgeable practice. The very real potential of alternative agricultural systems can be all too easily overlooked if they are misunderstood as nothing but the substitution of one nutrient carrier for another.
Even if there were evidence to document the rationale for a substitution approach, it would lose on the grounds of economics alone since dried blood and bone meal are prohibitively expensive on a farm scale. But, most importantly, the substitution concept is not germane to the actual objective of an ecological agriculture. That objective is the development of sustainable systems for maintaining the productivity of our farmlands.
The issue is not the substitution of one material for another but rather the long-range physical and environmental stability of food production itself. Supplies of blood and bone meal are no more assured in adequate quantities and at an affordable price than are supplies of chemically derived nitrogen and phosphorus fertilizers, which derive from finite and dwindling resources. Agricultural systems that rely on inputs from either nutrient source cannot be depended upon over the long term.
What must be depended upon is a system that maintains soil fertility principally by relying on those proven cultural practices (crop rotations, mixed farming, leguminous green manures, etc.), which nurture the inherent plant nutrient supply processes in the soil. When necessary, outside sources of locally available minimally processed soil amendments are employed to supplement the native soil raw materials. The aim of those farmers who understand the potential of an ecological system of agriculture is not to directly supply available plant food but rather to create and maintain optimal conditions of a balanced soil under which a healthy soil/plant economy can exist.
The concept of a sustainable fertility based on minimal import of fertilizer nutrients and maximum enhancement of the soil’s native fertility is not new and is not an unrealistic goal. It is based upon sound agronomic and economic data and is the principal motivation behind the development of a science and methodology of an ecological agriculture.
The definition of the adjective ‘ecological’ as used in the title of this paper is limited to agriculture. This ‘ecological’ agriculture employs production technologies that are sustainable over the long term. These technologies emphasize the well being of the soil, air, and water biosphere, the creatures that inhabit it, and the human beings who depend upon it.
A few years ago I was invited to explain the benefits of alternative agriculture to a large farmer’s organization. It was an instructive experience. I was informed that this group considered organic farming to be a dangerous revolutionary movement which advocated (1) banning all pesticides and (2) breaking up large farms into small farms and giving them to the poor. Whatever the background of this erroneous impression, it was an illustrative example of the distortions that can arise from hearsay and innuendo.
I first dealt with the obvious problem. They had confused alternative agriculture with two political movements – extremist environmentalism and land reform. I assured them that the principal concern of alternative farmers was farming. Secondly, I considered the reasons for their defensive position. Their attitude was fostered, on the one hand, by inertia and the human inclination to embrace the familiar. On the other hand, it was fostered by the naïve, sectarian, and at times accusatory manner in which many alternative ideas have been presented. No farmer is going to react positively to being called bad or stupid or willfully malicious because of following the dictates of a certain technology.
Farming is a tenuous profession and all farmers face similar difficulties. The conflicting masters of economics, yield, plant protection, and weather are not easy to serve. It must be stressed as a positive factor that there are many different management options opens to farmers. The agricultural application of alternative ideas is more likely to be accepted as a reasonable concept when understood as one of these options.
I explained that alternative farmers are looking for new solutions just as innovative farmers have throughout the ages. They deserve a measure of appreciation rather than scorn. Alternative farmers have personally taken financial risks in pioneering less input-intensive practices. Other farmers should appreciate that effort since they can learn and often profit from the results. It should be clear that the low input, environmentally sound production systems, which are successful for many large-scale alternative farmers, could be of direct practical and economic benefit to all farmers. If these systems were researched and detailed agronomic data made available, that benefit would soon be realized.
My recommendation to this farmer’s group was that it would directly benefit them if they used their political influence to demand that the USDA begin extensive research into alternative agricultural systems. My reasoning was straightforward. First, fertilizers and pesticides were two of their largest expenses. If there were any validity to the claims of successful alternative farmers (ie. much lower fertilizer bills, no need for pesticides, more money in the bank) then research which encouraged the adoption of those techniques by other farmers, would be of obvious advantage. And, secondly, even if nothing immediate came of the USDA efforts, once this farmer’s organization was on record as having demanded the research, that fact could be used to defend their present chemical practices since they had demonstrated their interest in adopting more environmentally benign techniques once they were researched and proven viable.
The distortions of the chemical-organic controversy have resulted in farmers considering alternative agriculture as an enemy. An unproductive adversary relationship has developed. My suggestions were an attempt to make my audience realize that the low-input systems of alternative agriculture were offering potential options that did not exist in the present system. The willingness of this farmer’s group to engage in open, honest discussion and their receptivity to the concepts presented gives me hope that this impediment can be overcome through more reasoned and precise communication.
Our agricultural scientists often appear distressingly similar to the Ptolemaic astronomers of Galileo’s time. Hampered by their false initial premise, they were compelled to lay epicycle upon epicycle to patch up their earth-centered theory of the heavens against the advances of mathematics and telescopy. Given the, as then, unproven nature of the evidence for the hypotheses of Galileo, the Ptolemaists, through the ingenuity of their patch-up artifice, were able to continue defending the plausibility of the Ptolemaic system. It was, however, a cumbersome, complicated and top-heavy system compared with the balance and harmony of the actual workings of the heavens, which was just then being realized. The parallels with agriculture – ie. the artifices and ever new “epicycles” of the chemical-industrial technology set against the emerging awareness of the balance and harmony which agriculture could attain by working with natural forces – are clear enough not to need further comment.
This is not to suggest, in any way, that the chemical system of agriculture is failing to produce food. It has certainly proven itself productive. Given inexhaustible inputs and a resilient environment, chemical agriculture can continue to operate as it has. The question, as was evident throughout the confrontation over advances in astronomical knowledge in Galileo’s time, is whether excessive defense of scientific status quo in light of increasing evidence to the contrary will backfire or no longer be tenable.
A letter to the editor in the May-June 1979 issue of the Journal of the Soil Science Society of America addresses the whole situation:
“Many examples in the history of science can be cited in which erroneous notions have persisted for decades, or even centuries, because of reluctance to consider alternative views… In every science there is a need for some daydreamers who…. provide some speculative notions regarding unknown or poorly known phenomena… We need their ideas and talents…Newton noted that the rest of creation apparently lay undiscovered about him like sand grains on a seashore. It still is…. or, at least, it still may be.”
Another comment on the same subject is found in the August 1978 issue of Ag Word. Lola Smith wrote:
“I cannot understand how [agricultural] scientists must reject so vigorously any suggestion that chemicals may be causing more problems than they are worth as presently used. Perhaps…. To admit that such is the case would be to admit that the system they have developed with such high hope and optimism may have to be scrapped – and thus a large part of their lives may lose value.”
To overcome this impediment it is necessary to recognize the invaluable resource that these experienced scientists provide. Every effort must be made to interest them in the potential of a different approach. The research needs for fine-tuning the emerging ecological agricultural systems are considerable. A new and exciting field is open to those scientists who have the imagination and understanding to aid agricultural progress in the direction in which it must inevitably go.
The principal economic impediment to change comes from those with a vested interest in the status quo, the manufacturers and purveyors of chemicals. Even back in 1940 Large noted the advantage of chemical salesmen over other information sources given the drive of the profit motive:
“There was nothing static about the commercial travelers; they pursued the farmer round the dairy, lay in wait for them on market days, bribed them with bread-and-cheese and beer, made demonstrations on their farms, and told the tale about the advantages of spraying with an optimistic enthusiasm that made the angels blush for shame.”
The effective salesman is a force to be reckoned with. But more effective than the sales pitch is the nature of the product. By their mode of action chemical agricultural inputs are presently almost a form of drug addiction. Once a farmer begins using chemicals he short circuits many previously effective natural components of his system and is, practically speaking, hooked into a perpetual and increasing need. In many ways agricultural chemicals come close to fulfilling the cynical definition of the industrialist’s ideal product which “ costs a dime, sells for a dollar, wears out quickly, and leaves a habit behind.”
Commercial interests are not going to voluntarily abandon their field and lay down their sales force in favor of an ecological agriculture. It would be extremely naïve to expect them to do so. In fact they have done just the opposite. The large chemical concerns have maligned the very idea of alternative agricultural practices with all their considerable propagandizing power. Ostensibly they fear they have nothing to sell to those who eschew fertilizers and pesticides and they are anxious to keep the infection from spreading.
That head-in-the-sand attitude is self-defeating and poor business. Just as other industries have shown imaginative adaptability and learned to profit from new ideas and changing realities, the agricultural chemical industries might find it a more productive approach to study the needs of the ecological farmers. Were they to do this they would discover the existence of a demand for a whole range of consultation and analytical services in lieu of products. The ecological farmer whose production is based on successful co-operation with natural systems needs far fewer hard inputs, to be sure, but he can benefit enormously from access to improved data on soil tests, plant tissue analysis, livestock health and metabolic analyses, computerized biological soil fertility and crop rotation programs, and the like.
The alternative to the chemical salesman is the trained professional analyst backed up by laboratory and research facilities. He sells advice rather than materials to the growers and is paid a retainer fee for advising the best overall program. It is certainly worth exploring the idea that a per farm or per acre charge for a service that enables farmers to keep their fingers more precisely on the pulse of their system would be cheaper for the farmer, possibly more remunerative for the agricultural chemical companies, and far less taxing on the resilience of our admittedly fragile eco-systems.
Even if we were to succeed in overcoming all the impediments discussed above, little real change would have been effected. Another group of impediments would soon be raised. Why? Because the most stubborn resistance comes from a far more fundamental level and the underlying human fears contributing to that resistance have not been dealt with. In order to go further and overcome our deep-seated prejudice to understanding and co-operating with nature, we must investigate the basis of this philosophical and psychological resistance.
John Stuart Mill’s statement from the 19th century expresses the prevailing attitude of misunderstanding and mistrust of nature in unmistakable terms:
“No one, either religious or irreligious, believes that the hurtful agencies of nature, considered as a whole, promote good purposes, in any other way than by inciting human rational creatures to rise up and struggle against them.”
Colwell confirms Mill’s sentiments for the present day:
“But though part of Nature, man’s unique function…lies in controlling and transforming the natural world, not piously seeking its guidance. How profoundly we believe this today. How could we help but believe it; the entire edifice of our civilization is built upon it. The Baconian conception of science as control over Nature is not only an intellectual. presupposition of ours, it is a deeply implanted emotional attitude as well.”
It is just those very “hurtful agencies” that Mill derides which I hope to show are beneficial if we only learn to understand them and their role in the natural order.
In this realm we are similarly acculturated by language. Our choice of words indicates how deeply the tendency to strike out viciously at “the hurtful agencies of nature” is ingrained in our character. Insects and disease “attack” the plant. They “ravage” the crop. Consequently, we do “battle” with them in order to “defeat” or “conquer” the “enemy”. We use bug “killer” in a spray “gun” to “blast” them. Van den Bosch paints a compelling verbal picture of the modern pesticide applicator portrayed as a weather burned, swaggering, macho, Western gunslinger “pumping the lethal load of his Colt .44” into the bad guy. Our primary view of the biological world and natural systems is one of fear and mistrust. Only rarely do we consider the improved relationship that could result from investigating, analyzing, understanding and co-operating.
Before ecological values can be a part of agriculture, humans must first learn to come to grips with their instinctive tendency to treat symptoms. Insects and disease in agriculture, as we shall show, are not the problem. They are symptoms, the symptoms of physiological imbalance in the plant. The cure is to search for and correct the cause.
In practice, causes are commonly sought only when no effective palliative is available as, for example, with the realization during the 20th century that trace element deficiencies were the causes of a number of baffling plant maladies. Humans are far more strongly inclined towards cosmetic solutions to agricultural woes – fast-acting, simple easy and cheap. If the visible, exterior indication of malaise, the pest, can be removed, we assume the problem is solved.
Human medicine provides a parallel example. If you have a headache, you take an aspirin. And, since the aspirin masks the pain, the symptom, there is no further compulsion to look for the cause. Has the headache been cured? No, it has only been masked. Roger Williams, in his brilliant Nutrition Against Disease, deals with this concept:
“… let me put the case as simply and bluntly as I can. Do you really believe you have headaches as a result of your system’s lack of aspirin?”
Medical science has embraced the symptom treatment mentality as eagerly as agricultural science and the results are almost identical. Williams continues:
“The fact is that medicine has become addicted to the administration of vast quantities of non-biological medications… The basic fault of all these weapons is that they have no known connection with the disease process itself. They tend to mask the difficulty, not eliminate it. They contaminate the internal environment, create dependence on the part of the patient, and … [erase] valuable clues as to the real source of the trouble.”
The significance of that statement to the theme of this paper is even more enhanced by the artifice of substituting ‘agriculture’ for ‘medicine’, ‘external’ for ‘internal’, and ‘farmer’ for ‘patient’.
In contrast to this situation it is interesting to note that where humans have created the technology, the situation is different and causes are well understood. Take automobiles as an example. The overheated engine is not refrigerated but the radiator is repaired and refilled with water. Instead of replacing the battery every few days, the generator is kept in good repair. Preventive maintenance is standard practice to avoid problems before they start and ensure the smooth functioning of the machine which is, after all, a kind of system of interlocked and interactive parts, each dependent on the other.
In the biological sciences, this same preoccupation with root causes does not exist. We did not create the natural system and for the most part we have not tried hard enough to understand it. We are even reluctant to acknowledge that we are a part of it. Our reaction is partially motivated by fear; fear of the unknown similar to that experienced by explorers into any new realm/ fear of losing control if we no longer arm ourselves with deadly weapons. Konrad Lorenz discusses a further fear:
“The reason why people are so afraid of causal considerations is that they are terrified lest insight into the causes of earthly phenomena should expose man’s free will as an illusion.”
I believe the object of this fear is misplaced. The illusory nature of man’s free will is most graphically exposed by our reliance on symptom treatments. Their use traps us in a web of dependence completely beyond personal control. Contrary to Lorenz’s statement, our free will would be enhanced as a consequence of natural causal investigations in agriculture. For example, at present we find ourselves increasingly helpless in the face of rebounding infestations of pests caused by the failure of our poison-based weapons. Our commitment to a symptom treatment approach leaves us without an alternative if our palliatives prove inadequate. On the other hand, an “insight” into “causal considerations,” which results in our understanding the parameters of natural systems, places us in a far more secure situation. By learning to manipulate natural systems to our advantage through enhancing certain of their own mechanisms, we increase human control. This is no longer a deterministic situation. On the contrary, human management based on understanding reinforces our sense of human omnipotence and consequently our freedom to choose without external coercion but in accordance with an ecological outlook.
Our fears have led to ignorance and our ignorance leads us into our own trap. The solution is not difficult. It simply involves learning how the natural system operates so that we will know how to cooperate with natural forces rather than attempting to ignore them or control them with chemicals. Wise minds have long urged the need to acquire knowledge for such a course of action. Back in 1880 Forbes wrote:
“From the consequent human interferences with the established nature of things, numerous disturbances arise… We must know the nature, extent, and most important consequences of the disturbances of this order… We must study the methods by which nature reduces these disturbances, and learn how to second her efforts to our own best advantage… By far the most important general conclusion we have reached is a conviction of the general beneficence of Nature, a profound respect for the natural order, a belief that the part of wisdom is essentially that of practical conservatism in dealing with the system of things by which we are surrounded.”
An extensive school of what I shall call ecological agriculture began in the late 19th century along the lines expressed by Forbes. Its principal interests were (a) understanding the functioning of the biological world, (b) getting to the cause of the problems arising from “human interferences with the established system,” and (c) learning to modify agricultural practices in order to work within natural laws while bending the system sufficiently to ensure that it accommodated our needs in food and fiber. Farming was not conceived of as a war but rather as a diplomacy of biological co-operation, a bending rather than a roughshod trampling. The pest and disease theorists of this ecological school were known as Predispositionists. They held that the physiological state of the plant as influenced by fertilization, climate, and cultural practices was the cause of pest problems. Within the limits of its genetic potential a plant would only be susceptible to pests if it had somehow been ‘predisposed’ by unsuitable growing conditions. The long-term solution was not to attack the pest but rather to improve the growing conditions for the plant. Attacking the pest, the symptom, was only a temporary cosmetic measure. The farmer needed to get to the root cause, the growing conditions, in order to achieve a lasting improvement.
It may come as a surprise to those unfamiliar with this hypothesis, and who find it fanciful, that there is an extensive body of published literature that thoroughly documents the potential for controlling pest problems through attention to the growing conditions and nutrient status of the plant. Such studies have been published for the best part of a century. A recent industry financed survey of the literature on just one small segment of this subject, the influence of potassium on plant health, cited 534 references out of some 1200 located and noted that since 1950 the number of new references available has doubled every decade. A number of excellent reviews of this entire subject are cited below.
The following six examples, from the experimental to the philosophical, should help to illustrate the case and suggest some of the mechanisms involved. Benepal and Hall at Kansas State investigated the relationship between an imbalanced supply of the major plant nutrients and insect infestation. Plants grown in cultures deficient in phosphorus, potassium or sulphur showed an increase in the non-protein free amino acid level in the leaves compared with plants grown with full nutrition. The more imbalanced the nutrition, the higher the free amino acid level. They observed a direct correlation between the increased free amino acid levels in the leaves and the increased number of insects feeding on the plant. The more imbalanced the nutrition, the higher the number of insects. When plants were grown with balanced nutrition, insect feeding was negligible or non-existent.
In a study of rice crops from 970 sites in Brazil, Primavesi et al stressed the importance of minor element nutrition in protecting paddy rice from the disease, rice blast. They determined from field experiments that plant infection, even under conditions especially favorable to the development of the disease – susceptible variety, unsuitable soil, infected seed, heavy nitrogen fertilization, and climatic conditions favorable to the fungus – could be prevented if sufficient levels of important minor nutrients, in this case principally manganese and copper, were available to plants.
Van der Lann in Holland carried out trials on the specific influence of organic manuring on nematode infestations. The nematodes caused only minor damage on the organic manure plots. He accounted for this difference as follows: (a) organic matter improved soil structure and moisture holding capacity and many plant parasites are known to cause less damage in improved soil; (b) organic matter increased soil micro-organisms and the nematodes may have been killed by their natural enemies; (c) organic manuring is known to affect the morphological structure of the plants and their roots and these changes may have made the plant more resistant to nematodes; and (d) physiological changes within the plant tissue also occurred which added to the resistance of the plant.
Thiem in Germany referred to both an absolute and a relative immunity to pests. The former he called genetic immunity and the latter pheno-immunity. He considered plants to be genetically immune when their resistance was such that a specific pest would never propagate and develop on them. Pheno-immune plants were those whose degree of resistance was such that they would be susceptible or resistant depending upon outside influences. If the resistance of a pheno-immune plant were to be adequately maintained then cultural conditions affecting soil structure, its physical and chemical make-up, and its biotic life must be carefully considered. Thiem further contended that an agricultural practice such as large-scale monoculture, often considered a causative factor of insect multiplication, would present no problem if cultural practices succeeded in assuring pheno-resistance.
Ross and Mehring of the USDA expressed a general overview in these terms:
“It is well known that crops grown on different soils differ greatly not only in yields but also in quality, appearance and resistance to spoilage… The view has been advanced that highly fertile soils may differ from those that are less productive in that they contain the proper balance of all the essential plant-food elements for maximum growth without any excess or deficiency of any mineral constituent.”
And, finally, Baker and Cook summarize the philosophical argument in their thorough review of the subject:
“Chemical control is essentially active and provides the grower with action therapy. If one chemical fails, another can be tried. There is satisfaction in direct engagement with the enemy, even if one wins all the battles and loses the war. Non-chemical control, because of its slower effect (often over a period of years), is essentially passive; a greater sense of commitment, of understanding of and confidence in the methods, is required for non-chemical means… Man, an inhabitant of the more violent aerial habitat, is inclined to think that large rapid changes are necessary. With a better developed worm’s eye view of events, he may come to see that gently ‘nudging’… can be far more effective in the long run than overkill or ‘dynamite’ treatments.”
Let me give a short summary of the points made so far. If we can teach ourselves to realize that insects and disease in agriculture are symptoms of a deeper problem, we can learn from them to search for their causes. The extensive literature on the subject strongly suggests that the cause lies in the physiological dysfunction of the plant as a result of imbalanced nutrition or unsuitable growing conditions. One effect of physiological dysfunction on the plant is to increase its susceptibility to disease and enhance its suitability as a source of nourishment for insects. In consequence, to resolve the problem rather than only mask the symptoms, the practices of the farmer must find their genesis in a cause correction thought pattern. The farmer must emphasize those practices that benefit the well being of the plant. This system and cause-oriented approach will require a major shift in attitude and that is why I consider it the key impediment to the adoption of an ecological system of agriculture.
For those farmers wishing to attempt such a shift, general experience has shown that those practices which stimulate the biological activity of the soil (organic matter, mineral balance, near neutral PH, soil aeration, adequate moisture, crop rotation, mixed stocking, to name a few) are the most widely effective and least expensive in enhancing the pest resistance, the yield, and the biological quality of the produce. In many years of market growing I have never found any need for pesticides once I succeeded in creating growing conditions that optimized the physiological well being of the crop. This was neither an expensive nor an impossible accomplishment. In each case the creation of those ideal growing conditions did not require more than the minimal resources of the small farm or more than a reasonable understanding of soil science and agronomic principles. What it did require was a thought pattern that approached the problem from the point of view of cause correction rather than symptom treatment.
I would be remiss at this point if I did not extend the discussion one link further up the food chain to include the consumer of the plants. We can then ponder the obvious questions that have been raised. Are we humans also governed by these rules? As in the case of plants, is our health, vigor, and resistance, our “biological quality,” determined by our “growing conditions” and the “nutritional balance” in our cuisine? If we have followed this positive approach to plant health and have optimized all factors of the plant’s growing conditions in order to turn out a plant of the highest biological quality, will the consumption of that plant be a factor in optimizing our nutrition and subsequent well being?
Galileo stated that he would have to “mold anew the brains of men” in order to change the prevailing view of cosmic patterns. Such a course also lies ahead of the effort to change the direction of agricultural science. If successful, the influence of a cause rather than a symptom approach to problem solving would be significant beyond agriculture.
In effect, the new ecological philosophy possesses the potential to transform the ordering of our non-agricultural experience, rather than the excesses of our anthropocentric psychosis dictating a destructive course for agriculture. The thought is appealing that if in the most basic of human endeavors, agriculture, we can learn to live in harmony with the biological limits of the planet, might not we similarly learn, on the plane of human existence, to live in harmony with ourselves?
 USDA Study Team on Organic Farming, 1980, Report and Recommendations on Organic Farming. U.S. Department of Agriculture, Washington, D.C.
 de Santillana, G., 1955. The Crime of Galileo. University of Chicago Press, Chicago, IL.
 Large, E.C., 1940. The Advance of the Fungi. Jonathan Cape, London. p. 332
 Baker, K. F. and Cook, F. J., 1974. Biological Control of Plant Pathogens, Freeman and Co., San Francisco, CA
 Cited in Colwell, T. B., Jr. 1970. Some implications of the ecological revolution for the construction of value. In Human Values and Natural Science, Laszlo, E. and Wilbur, J.B. (Eds.) Gordon and Breach, New York. P. 246.
 Ibid. p. 247
Van den Bosch, R. 1978. The Pesticide Conspiracy. Doubleday, New York. p. 18
 Coleman, E.W. 1980. Turning back the clock? The Coolidge Center Quarterly. 1(3): 1-2
 Williams, R. 1971. Nutrition Against Disease. Pitman, New York. p. 9.
 ibid. p. 9
 Lorenz, K. 1967. On Aggression. Bantam Books, New York. p. 233.
 Forbes, S.A. 1880. On some interactions of organisms. Bull. Ill. State Lab. Nat. Hist. 1(3): 13-17
 Coleman, E.W. op. cit. p 1.
 Yarwood, C.E. 1959. Predisposition. In Plant Pathology, Horsfall, J.H. and Diamond, A.E. (Eds.) Vol. 5:521-62
 Perrenoud, S. 1977. Potassium and plant health. International Potash Institutes, Worblaufen-Bern, Switzerland.
 Coleman, E.W. and Ridgeway, R.L. 1982. Role of stress tolerance in integrated pest management. In Sustainable Food Systems (in pub), Knorr, D. (Ed.) (AVI Westport, CT.
E1-Tigani, M.E. 1962. Der Einfluss der Mineraldungung der Pflanzen auf Entwicklung und Vermehrung von Blattlausen. Wiss. Z. University Rostock 11:307-24
Johnston, N.E. 1968. Insect attack in relationship to the physiological condition of the host tree. New York State Agriculture Exp. Stn., Cornell University, Ithaca, NY.
Lleath, K.T. and Ratcliffe, R.H. 1974. The effect of fertilization on disease and insect resistance. In Forage Fertilization, Mays, D.A. (Ed.). Am. Society of Agronomy, Madison, WI. Pp.481-503.
 Benepal, P.S. and Hall, C.V. 1976. The influence of mineral nutrition of varieties of Cucurbita pepo 1. On the feeding response of squash bug Anasa Tristis De Geer. Am. Soc. Hortic. Sci. 90:304-12.
 Primavesi, A.M., Primavesi, A., and Veiga, C. 1972. Influences of nutritional balances of paddy rice on resistance to blast. Agrochimica 16(4-5_: 459-72.
 Van der Lann, P.A. 1956. The influence of organic manuring on the development of the potato root eelworm, Heterodera rostochiensis.Nematology 1:113-25.
 Thiem, von H. 1938. Uber bedingungen der massenvermehrung von insekten. Abr. Physiol. Angew. Entomol. Berlin-Dahlem 5(3): 229-55.
 Ross, W.H. and Mehring, A.L. 1938. Mixed fertilizers. In Soils and men, Agric. Yearbook 1938. U.S. Department of Agriculture, Washington, D.C.
 Baker and Cook, op. cit. p. 23-27.
 Hainsworth, P.H. 1954. Agriculture: A New Approach. Faber, London.
Krasilnikov, N.A. 1958. Soil Microorganisms and Higher Plants. Academy of Science, USSR. (Washington, D.C.: Office of Technical Services, U.S. Department of Commerce.)
Waksman, S.A. 1952. Soil Microbiology. John Wiley and Sons, New York.
 De Santillana, G. op. cit. p 4.