Soil Fertility and Its Health Implications

It is scarcely necessary to say that dentists have more than a passing interest in soil fertility, since they know that strong, healthy teeth contain a high concentration of calcium and phosphorus–nutrient elements that head the list of minerals drawn from the soil for sustenance of plant and animal life. Of the total gross weight of the teeth as part of the human skeleton, one-fourth is calcium and one-eighth is phosphorus. Of the tooth enamel, one-third is calcium and one-sixth is phosphorus.

As cardinal requisites of a fertile soil, calcium and phosphorus in the form of limestone and superphosphate are the two foremost fertilizers or soil treatments used by well-informed farmers. Too frequently, however, these treatments are regarded merely as a means of obtaining greater tonnage or more bushels of crops per acre.

But when shortages in bulk of foods confront us, it is all the more essential that we improve the quality of that bulk. It is the soil on which, after all, the health qualities of foods depend. When teeth are calling for much calcium and phosphorus, defective teeth are not far removed from crops that are calling in vain on the soil that is deficient in these two mineral constituents of man’s skeleton and teeth.

The Dental Profession Has a Real Stake in Soil Fertility–In addition to calcium and phosphorus, there are about ten more growth-promoting, body-building nutrients on the list of fertility elements that soils must provide for vigorous, healthy bodies and sound teeth. Shortages in any one of these elements needed in body construction, or in catalytic service in body or plant growth, will reappear in the human family as health deficiencies. We cannot therefore afford to tolerate shortages in the soil’s store of these truly “grow” foods.

Besides these dozen so-called “grow” foods, or elements coming from the soil, every growing body and every growing plant must have what can conveniently be called energy providers or “go” foods. The elements constructing such compounds are, in the main, carbon, hydrogen, and oxygen. They come from the air and water. Nitrogen also comes from that source, so that as much as 95 per cent of plant mass or animal body weight is combustible. It serves in provision of energy and in giving bulk and weight.

Photosynthesis and Biosynthesis–Because the recognition of mass is a simple mental impression, the concept of bulk is always easily and quickly caught. So commonly are crops measured by weight that we are just now coming to realize that the “growth” quality, or the nutritional value of herbages is not the same as the tonnage value. A bushel of corn is always 56 pounds, but one bushel may be nourishment while the other is not, as judged by livestock growth. Plants attain mass of growth through the service of sunshine as it makes carbohydrates through use of the sun’s energy in the chlorophylous leaves. This process of chemical synthesis of carbon, hydrogen, and oxygen into carbonaceous products gives tonnage, but surely this photosynthetic behavior does not guarantee animal or human nourishment when it results in trunks of trees consisting only of just so much woodiness. Sunshine, fresh air, and water–processed through the suprasoil activities by plants–may be responsible for 95 per cent of plant bulk, yet contribute nothing to nourishment of higher life forms.

Nutritive values of herbages result from the synthesis of compounds within the growing plants, as for example, those that give rise to the seed and will feed our animals. These values are dependent on the calcium, phosphorus, magnesium, etc., that come from the soil. Animal life finds plenty of bulk for consumption. Recall hastily, if you will, the many plants which animals refuse to eat, or the many we call weeds. Nutritional deficiencies result from the failure of that vegetative bulk to have within itself the products of synthetic activities by the plant quite aside from products directly from photosynthesis. We need to appreciate what may well be called the “biosynthesis” or the synthesis by the life of the plant that depends not on air and water, but on the delivery by the soil of its complete list of soil fertility elements to be constructed by the plant into what is truly food substance.

In considering plants as phenomena of growth, we may well think of them first as a photosynthetic performance. This builds the woody frame of the plant, uses only limited amounts of soil fertility, mainly potassium, as catalytic agents, to set up the factory and provide its fuel supply. In the second place, plants are a biosynthetic performance, into which the soil fertility enters more directly to have its phosphorus, sulfur, nitrogen, etc., synthesized into proteins, vitamins, and other compounds truly valuable for body construction rather than for fuel only. It is the soil fertility much more than the sunshine and fresh air that determines how well the plant really gives us nourishment. It is this biosynthesis and not the photosynthesis whereby soil fertility takes on its significant implication in your health, in my health, in your teeth and in my teeth.

Virgin Plant Growth Concentrated the Soil Fertility in the Surface Soils for Help to Man–That the entire land surface of the earth cannot be generous in its provisioning of human and animal life becomes almost axiomatic when it is known that the soil must deliver about a dozen chemical elements. Soils constructed under good physical conditions, and stocked with such a large number of nutrient elements, must of necessity be the exception rather than the rule. Plant life in virgin condition has been sending its roots down and searching through large volumes of soil to collect and assemble in the surface layer as organic matter or humus, these many elements needed. Hundreds of years of virgin condition have kept within the plant life, as a cycle of growth, death, decay, and re-use, these nutrient-mineral elements from the soil. It is this feature that makes surface soil so valuable while subsoil is so unproductive.

Soil Construction and Soil Destruction–Naturally, soils vary widely as to their fertility since soils are temporary rest stops of rock en route to the sea and to solution. In lower rainfall areas the soil is finely ground rock. It is mainly mineral, with little clay and little water for plant growth. The plants grown there are mineral-rich, however. More rainfall gives more clay, more plant growth, more organic matter to decay. It also leaves a rock reserve to supply the clay as it gives up its nutrients to the plants. In central United States with its prairie areas, we have soils now in the stage of maximum of construction of clay that is in balance, or equilibrium, with a generous reserve of rich minerals to maintain productivity. With no more than 30 inches of rainfall along approximately the 97th meridian of the United States, we have the Midlands, where the animals raise themselves and human health is good as indicated by the fact that seven out of ten draftees pass inspection in Colorado while only three out of ten do so in a southern state.

Fig. 1–The curves represent the gains in weight per head by lambs consuming constant weight of grains and hays per head per day, but with the different hays grown on adjoining plots given different soil treatments. The efficiency of the meat-making animal depends on the efficiency of the food synthesis by the plant in terms of the soil that controls it.

 

With higher annual rainfalls and higher temperatures, the rocks are so highly weathered and the clay is so changed that it represents soil destruction. This is the prevailing condition in eastern and southeastern states. In terms of this degree of soil development we can see the basic principles of nutritional troubles in the southern states, of limited populations in the tropics, of population concentrations into limited areas of the temperate zones, of customs whereby aborigines survive while the white man fails utterly, and numerous seemingly uncanny situations where the influence of soil fertility upon the human species is not yet appreciated.

Crop Juggling Disregards Soil Fertility–An ecological survey with tabulations of plant species is not needed to locate the forests in the northern regions, in the tropics, and in eastern and southeastern United States, nor to locate the prairies in central United States, and the barrens in the West, excluding the western coast. Underlying this seeming agreement of greater vegetative production in forests with higher rainfall, and vice versa, there is the soil fertility. We have not been connecting the different crops, their tonnage production per acre, and their chemical composition in terms of nutritive value for animals with the soil fertility. That the scantily growing buffalo grass of western Kansas was more nutritious because of more fertile soils than the lush bluestem of eastern Kansas on the less fertile, more leached soils was recognized by the buffalo. This brawny beast stayed on his scant grazing because it meant growth, muscular and bony body, and good reproduction. There was no natural obstruction to prevent his coming eastward, had he desired to move to get more bulk per acre.

Fig. 2–Animals discriminate very judiciously by grazing different plants to different degrees. That the animal is balancing its diet according to the plant composition determined by the soil is not commonly appreciated. This instinct may be serving the animal better than it is in the human.

 

More protein in the wheat as we move westward across Kansas follows the same course, with the less leached soils in central and western Kansas giving high protein in wheat. But in place of recognizing soil fertility as the controlling factor, we have been ascribing the difference to rainfall or to plant pedigrees. Plant breeding has been credited with wonders when we think of hybrid corn. But to date no geneticist’s creation has yet come forward that can tolerate starvation or the lack of soil fertility.

Crops have been introduced, moved from place to place and pushed to the very fringes of starvation, while we have kept our attention fixed on the pedigree in place of the plant’s nutrition. During this crop juggling, the chemical composition of the plant has shifted. Photosynthesis has come into prominence while biosynthesis has almost disappeared. The crop has retained its service in giving energy values but lost much of its service as a growth food and carrier of soil minerals elaborated into organic complexes of nutritive value. We have gone from proteinaceousness and high mineral contents. in plants grown on soils under construction through lower rainfall to carbonaceousness and mineral deficiencies in plants grown on soils under destruction through higher rainfalls. Nutrition at the same time has descended from a level of bonebuilding, brawn-making, and fecund reproduction to hydration, obesity, fattening performances and other excesses of weights with weakened bones and flabby muscles, to say nothing of carious teeth, alveolar bone disintegration, and other oral troubles.

Fig. 3–Fertilizer treatments of the soil register their beneficial effects in the plant, but more noticeably in the physiology of the animal as indicated by better weight, wooly fur, bones, and other body products and functions. On the left, the rabbit and bones record the results of lack of soil treatment in contrast to the effect of treatment measured by similar gauges on the right.

 

Declining Soil Fertility Brings the “Sweet Tooth”–Declining soil fertility has been pushing out of the agricultural program those crops drawing heavily on the soil fertility, and naturally of high nutritive values. As such crops failed to produce tonnage, we have sought other crops maintaining the tonnage production per acre but failing to provide the nutritive equivalents per acre and the nutritive concentration or food value per pound. Carbonaceousness, consequently, has come into prominence, while proteinaceousness and high mineral contents have dwindled.

Declining soil fertility has been provoking the shift to feeding our animals on fattening feeds, and our own shift to soft wheats, and to starchy and saccharine elements in our diet. Our “sweet tooth” in a dietary sense has become a carious tooth in a dental sense as a result of the unobserved and unappreciated exploitation of the soil fertility, and shift in dominant plant composition.

Failing Skeletons Go With Failing Teeth–When the simplest expression of the chemical composition of bones and teeth puts these two together in the same category with their ash containing 894.5 parts of calcium phosphate per thousand parts, these two soil-borne elements, calcium and phosphorus, are lifted into prominence. This dare not, however, crowd out the 15.7 parts of magnesium phosphate, the calcium fluoride, the chloride and the carbonate of calcium as 3.5, 2.3, and 101.8 parts, respectively, and the 1.0 lone part of iron oxide. That this complexity in chemical composition of the teeth is no mere accident is well worth considering, and that it is a specific combination which makes for sound teeth only by good metabolism to maintain its specificity is also worthy of serious consideration. Shifts in the fluorine content, that makes up less than .013 per cent of the enamel of the teeth, are known for the troubles they cause. Can we not then appreciate the inevitable incidence of tooth and skeletal troubles when the supplies of calcium and phosphorus in the foods fluctuate widely in amounts and in chemical combinations ingested, while we keep our eyes fixed on food bulk only?

Animal studies are pointing out the widely variable thickness, size, strength, and other properties of bones of animals according as they are fed different hays, the same hays from different soils, or the same hays from the same soil given different soil treatments, such as limestone and phosphate. Hidden away as it is within the animal’s body, the skeletal structure may be undergoing drastic shortages in calcium and phosphorus that are readily passed over without concern. Surely the jaws carrying the teeth cannot escape registering these same irregularities taking place in the other skeletal parts.

To the Drugstore for Cure Rather Than to the Soil for Prevention–Even though the practice of salting domestic animals has been with us for scarcely a century and a half, we have taken readily to the belief that the deficiency in any essential element in the diet can be met by its ingestion as a simple chemical salt in its ionic and molecular forms. With sodium and chlorine, both of which are monovalent and extremely soluble, accepted in the common salt form by domestic animals and searched out in the “salt lick” by wild animals, there may be serious error in concluding that deficiencies of calcium phosphates in the diet may be met by ingesting the salts of tricalcium phosphate or calcium and phosphorus in one or the other acid phosphate forms. Calcium is a divalent and phosphorus is a pentavalent ion. The two are closely associated or combined chemically wherever phosphorus is found in Nature. They serve such important roles in plant life where sodium and chlorine are not considered essential that it should seem fallacious even to postulate that calcium and phosphorus as salts can serve as effectively in both processes as when they are part of the compounds elaborated by plant synthesis.

The eating habits of the animals themselves offer suggestions. The eating of bones by cattle is not common. It occurs only after the animal arrives at certain stages of emaciation resulting from feeds deficient in phosphorus. This is quite different from their behavior relative to sodium chloride of which the consumption does not suggest itself as an act of desperation.

The behavior of rachitic bones suggests that the advent of calcium and phosphorus into the digestion via the plant as it has taken them from the soil is more effective when these come through this route whereby it is synthesized as organo-complexes rather than simple mineral salts. When a rachitic bone is cut longitudinally and immersed in ionic calcium phosphate solutions, the calcium and phosphorus are not readily deposited in the unmineralized bone parts. However, when such a bone is placed in a solution of calcium hexose monophosphate or calcium glycerophosphate, it absorbs the calcium and phosphates, to deposit them as minerals in the zone of the rachitic bone prepared for calcification. Such behaviors suggest that the organo-calcium phosphate may be a much more efficient means of introducing these bone-building ions into the skeleton and teeth than are calcium and phosphorus ingested simply as ionic salts.

Yeasts, as fermenters of sugars, require phosphates in order that this reaction giving off carbon dioxide may proceed. The phosphate acts seemingly as a catalyst. It enters into combination in one step in the process, but is not a part of the product. Thus, the phosphate is not serving in construction of the body of the yeast cell, or as a part of it. Rather it is serving in the chemical reaction that provides the energy for the life of the yeast. Calcium phosphate, as it serves in the energy reactions or metabolism of higher life, is still not a known phase of its behaviors in nutrition.

Here is the suggestion that the calcium and phosphate ions do not use the plant merely to hitchhike from the soil to the stomach of the animals. Rather it suggests that while these nutrient elements are helping in the biosynthetic performances within the plant, they are functioning in its metabolic performances and putting themselves into some unique organic combination through which they can move into the construction of the bones and teeth so much more effectively.

Then, too, when calcium gluconate, another calcium organo-complex injected into the blood stream, is an effective cure for milk fever, it emphasizes the plausibility of the belief that calcium and phosphorus in the blood stream in nondialyzable or colloidal form may be playing far more essential roles than we have been inclined to appreciate while focusing attention on them mainly in their ionic behaviors. Much about the physiologic activities of these two nutrient elements remains to be learned, but surely there are strong suggestions that as they play these roles we can aid their functions more from the soil forward by using them as fertilizers in the plants and thus for preventions, than from the drugstore backward and thereby as cures for nutritional troubles by which havoc has already been wrecked in the body.

Other Aspects of Soil Fertility–Your attention has been focused specifically on but two nutrient elements of the dozen (possibly more) essential ones coming from the soil for human sustenance. If recognition of the deficiencies of these two in the soil has led us to understand the irregularities in plant physiology of the food crops we eat, and deficiencies in our teeth, our skeleton, and our own body physiology as all these provoke bad health, we need to prepare ourselves for more troubles arising as the remaining nutrient elements are being drawn from the soil. Potassium has long been registering its shortages for crops, but fortunately is so bountifully supplied by food plants that our bodies excrete rather than hoard it. Magnesium, however, which is the next on the list, cannot be viewed with so little concern. Shortages of this element in the soil are already impending. Heavy limings with calcium limestone only and soil conservation activities without attention to magnesium may throw a panic into body physiology and sound teeth. Elements no more plentiful than fluorine required in drinking water by quantities as low as one part per min and coming in milk in from 5 to 25 parts per ten million are only beginnings in our thinking about several elements to which quantitative attention for health’s sake has not been directed. We are soon to face the health problem linked with all the dozen (possibly more) nutrient elements contributed by the soil as we have just begun to connect rickets, teeth decay, and other troubles with calcium and phosphorus. With such a large list to be compounded into medicine by the drugstore, surely in desperation we ought to turn away from medicinal concoctions for cure and learn to put fertility into the soil so as to give help to Nature to nourish us for disease prevention instead.

Public Health Calls for Conservation of Soil Fertility–The importance of the soil as the basis of our nutrition has not yet been appreciated. For too many of us, food comes only from the grocery and the meat market in paper bags, fancy cartons, glass bottles, and tin cans. We are measuring it only by weight or cost per plate. Milk is still sold by the gallon and by its fuel value in terms of fat content, when milk may be so deficient as to give rickets even to the calf taking it, uninjured by aeration and pasteurization, directly from the mother cow. Milk, which is closely connected with reproduction, is lowered in its quality even as the function of reproduction, itself, is impaired by nutritional deficiencies resulting from neglect of the soil. Reproductive cells, both as egg cells in the female or sperm cells in the male, are a physiologic output by the body for reproduction–just as milk is food for service to the young in the same reproductive process. Egg cells and sperm cells defective because of deficient soil fertility and malnutrition are just as possible physiologically as is defective milk.

To the observant dentist, teeth and the mouth as a whole reflect the nutritional plane of his patient and thereby reveal not only the irregularities in the quality of his food, but should point much farther back to the plane of soil fertility in the region where the patient’s food was grown. With that extension of the view of your mind’s eye as you look into the mouths of children, we trust you will catch some suggestion that you in an office on the paved street have some share in conservation of the soil that is owned and managed by the man of the country who may seemingly be miring in the mud. That mud is becoming more precious for health’s sake.