Soil Fertility and Wildlife Cause and Effect

Always interested in food, the public recently has developed a new, intense interest in the nutritive value of food ingredients. Limited as to the quantity of their food, the consumers are focusing their attention more sharply on the quality of each item, particularly its service in proper nutrition.

Progress in the science of feeding domestic animals is telling us that chemical analyses for carbohydrates, protein, fats, fiber, and minerals are not enough as a measure of over-all values of feeds. Then, too, it must also be granted that the vitamin requisites are not yet fully understood. Much less appreciated is the recently recognized fact that the fertility of the soil growing the forages and grain feeds enters as one of the controls of their nutritive value. In support of the belief in the soil fertility as a determiner of food quality, we are submitting for your consideration the postulate that the ecological array of wildlife may be a reflected picture of the variable value of feeds according to the soil fertility growing them.

When food is the foremost ecological factor, not so much in terms of bulk but rather in terms of nutritive quality, and when the latter is connected more closely with soil fertility than the former, surely we must grant that the soil producing the food plays an important role. We must guard against the belief that wildlife–the same belief is erroneously held too often for our domestic animal life–can thrive well merely because it ingests ample amounts of vegetative bulk. Vegetation may be highly defective in nutrient qualities because of the low fertility of the soil that produces it.

Viewed in a simple way, growth consists of a group of interrelated chemical syntheses, or construction processes starting with the simple chemical elements of the soil and moving into greater chemical complexities through successively dependent life forms. For animal life seventeen of them are essential. For plant life fourteen, at least, must be provided. Four of these constitute about 95 per cent of the body of either animal or plant. These are oxygen, carbon, hydrogen, and nitrogen, representing in the human body, for example, 66.0, 17.5, 10.2, and 2.4 per cent, respectively. They originate in the air and water, hence as widely distributed elements in gaseous and fluid forms their supplies are free-flowing. They are not fixed and do not occur as limited supplies in restricted localities.

In contrast to the four elements of meteorological origin, thirteen elements are demanded from the soil by animal life. Six of these are present in the human body in amounts larger than one-tenth per cent. They are calcium, phosphorus, potassium, sodium, chlorine, and sulfur with 1.6, .9, .4, .3, .3, and .2 per cent, respectively. The remaining seven elements have magnesium at the head of the list amounting to .05 per cent, followed by iron as .004 per cent and then by copper, .00015, manganese, .0003, and iodine, .00004, followed by cobalt and zinc in amounts too small to be accurately specified, but, nevertheless, essential (Bogart, 1943). In addition to those on the last list of seven for animals, plants require boron not seemingly needed by animals. But plants do not require cobalt, sodium, and chlorine, which are required by animals.

Calcium and phosphorus serve in organic combinations but not so effectively in “salt licks.” Calcium and phosphorus are at the head of the list of thirteen elements coming from the soil. They have long been recognized as essential for all life, and have been used extensively as fertilizer applications on the soil for plant production. Their shortages in the soil have been contributory to deficiency diseases and other animal troubles. Calcium in the blood plays a role in the heart rhythm, in the control of muscle tone and in the clotting ability of the blood. Phosphorus is an essential constituent of many important proteins and is integrated with the body mechanisms for making use of energy foods. Calcium and phosphorus, which are closely connected in natural mineral compounds, much as they are in fertilizer service, are closely related in their contributions toward animal requirements when they are deposited in bones and teeth in nearly fixed proportions and are secreted in nearly fixed amounts in milk.

Calcium and phosphorus constitute over 90 per cent of the mineral matter in the body. Most of the calcium, and approximately 80 per cent of the phosphorus, are in the skeleton and serve the obvious function of mechanical support. This function leads to the erroneous concept of their fixity and inactivity. This concept fails to engender an appreciation of the readiness with which they move into and out of the bones in relation to: (a) The supplies in the food, (b) the intake of Vitamin D, and (c) the activity of the particular hormone produced by the parathyroid glands. The additional fact that these two elements combine themselves in varying proportions with hydrogen or other elements as a possible third part in their combinations to form salts and then as combinations with many other elements in colloidal forms, complicates the picture so much that to date the role played in animal life by these two soil-given elements is not extensively charted.

When the calcium and phosphorus as colloidal organic combinations with sugar or with glycerol (e.g. calcium hexosemonophosphate or calcium glycerophosphate) deposit the inorganic calcium phosphate into a richitic bone more effectively than is done by ionic solutions, there is a suggestion that our attention to these two elements in mineral form, or ionic form, has not led us to realize that they may be giving a greater service in animal life when they come from the soil through the. plant which synthesizes them into these more beneficial organo-colloidal combinations. Plant synthesis of these soil-given nutrients–calcium and phosphorus–may not only put them into more serviceable colloidal combinations, but it may also package with them some other complexities, like vitamin D, for example, so that a small amount of these two nutrients in the forms resulting from natural plant synthesis is far more valuable than much larger quantities ingested as salts or other mineral combinations of calcium phosphates. Here is a suggestion that nutrition of wildlife and domestic animal life by working forward from the soil is better than backward from the mineral pile or the drugstore.

What has been said in so much detail about calcium and phosphorus, which are at the head of the list of thirteen soil-given nutrient elements, will readily suggest the possible complexities and importance of the other ten or eleven essential chemical elements coming to food service for wildlife from the same source. When absence or even shortage of any one of these elements can be disastrous, there is still the handicap when any one is not in the most suitable organic combination as a result of failing plant syntheses. The studies of calcium and phosphorus coming from the soil as they control the distribution of wildlife and of domestic life prompt ready consideration of the broader principle that the ecological array of all life–including even man–is a picture of variable nutrition in terms of the soil fertility of the region producing the foods. In other words, life is according to the soil fertility of Mother Earth that nurses it.

That those interested in wildlife should be concerned about the high mortality in the young has its counterpart in the concern by men in animal husbandry about the similar situation in the young of domestic animals. Dr. Ralph Bogart of the College of Agriculture of the University of Missouri (Bogart, 1944) passes on the estimate that 40 per cent of the pigs farrowed in Missouri do not live to weaning age. He reports that eight-tenths of the loss, or 32 per cent, of the pigs farrowed occur before they are two weeks old. 

That the deficiencies in soil fertility are back of this sad picture has not been generally appreciated. Instead of calling on the agronomists and soil scientists to help stock the soil with calcium, phosphorus, and other essentials for prevention of this trouble, we are prone to call on the veterinarian for its cure. The fecundity of the female is not a matter of fattening foods of photosynthetic origin in the plant, but rather of growth-promoting foods of biosynthetic origin there. One swine producer of Missouri (Powell, 1944), who gives attention to his feeds as they come from fertile soils for his brood sows, gives a high figure of pigs per litter and such high vigor of them that during the last 3 years each of about 80 brood sows has sent 17.5 hogs to the market. His sows have shown less than 25 per cent loss between farrowing and weaning.

The fecundity of the male, too, has been demonstrated by rabbits (Albrecht, 1943) as dependent on soil fertility when males fed lespedeza hay from soil given phosphate only threatened to become sterile, while those fed hay made from the same variety of forage plant grown on soil fertilized with both limestone and phosphate remained active in all the respects that mark the virile male as different from one castrated. The significance of the soil fertility as it enables these male rabbits to serve as progenitors of their kind rose decidedly in so short a time as 3 weeks when the hays for the two lots of rabbits were reversed.

Here then is evidence that wildlife as it reproduces and multiplies itself is connected with soil fertility. It is not necessary then to remind you that maternal body growth, foetus development, and birth must each come in full function in presentation of a new body. Body physiology in total of both male and female must be doing well long before reproduction is possible. Reproduction is seemingly the climax of all physiological behaviors. It is the keystone, as it were, between ascendent life activities on one side and decadent life activities on the other. When growth is a constructive performance depending on the soil fertility for its building materials, we ought to see that mating, foetus formation, and the development of a body into bone and brawn are much more closely connected with the soil-given elements calcium, phosphorus, and others than is the fattening process that uses carbon, hydrogen, and oxygen contributed by water, fresh air, and sunshine. Perhaps you may not be a soil chemist, but, nevertheless, you will be interested in a brief scan of the rainfall and evaporation of the United States as they illustrate the construction of soils in the western half, exclusive of the Pacific Coast, and the destruction of soil in the eastern half. (Figure 1.)

Figure 1. Soil development through all stages, from rock to solution, is illustrated in the United States with the more fertile soils in the Midlands where the bison was common.

 

Soils are a temporary rest stop of rocks enroute to the sea, while being pushed from solids to solution through the agency of water as a solvent and as a transporter. In regions of lower rainfalls, the rocks are broken into small fragments. They are not extensively dissolved and only the more soluble elements, like sodium and potassium, are chemically broken out of the rock minerals. Only a small portion of the rock is decomposed far enough to form clay. Soils are then dominantly sandy. The clay, too, has not become highly stable, nor has it taken on so completely the capacity to hold and exchange nutrients. In fact, it is a clay with properties distinctly characteristic of the low rainfall climate, and associated with soils whose sandy and silty mineral fragments are scarcely different from the parent rocks contributing them.

With increasing amounts of annual rainfall, and especially as these are made more effective by higher temperatures, there is a greater accumulation of clay in the soil. The minerals, too, have not only been more finely broken down, but those more soluble have been leached out and only those more stable and insoluble are left to make the mechanical framework of the soil. The clay has been submitted to more drastic chemical treatment, with the resulting product more stable and more active in holding and exchanging chemical elements including the hydrogen to give it the characteristics of soil acidity.

This increased chemical activity in holding and exchanging positively charged ions is the acme, or top, of soil construction when along with the significant amount of clay and the exchangeable nutrients it carries, there remain in the silt and sand separates of the soil enough minerals other-than-quartz to represent a reserve of plant nutrients to be later broken out for plant nourishment. Such are the soils in the Midlands of the United States, or those in a broad belt extending north and south with approximately the 97th meridian as the central line. The chernozems, or the black and dark prairie soils, are distinctly typical of soil construction at the maximum, or soil destruction at the minimum. Here is the great lasting belt of nourishing resources for life in the United States. It is closely delineated by the wheat belt, and, along with the other wheat belts of the world, emphasizes the small areas that can truly serve as more nutritious food sources of this nation and other nations involved in the world war struggle.

The eastern United States with its higher rainfall, and particularly the Southeastern States with both rainfall and temperature much higher, represent rock breakdown carried more completely toward soil destruction. The mineral particles remaining in the sizes of sand and silt are mainly quartz that contributes nothing to nourishment of life either lower or higher. The clay formed under such intensive weathering is also of a far different mineral and chemical make-up than that with high capacity to hold and exchange other nutrients. Tropical, or red clay, does not hold even the non-nutrient hydrogen. With the reddish color of the clay, there is less activity of holding in exchangeable form those elements of nutritional service as well as of soil acidity. Our southern soils then are not seriously acid, nor can they hold significantly large supplies of calcium, magnesium, potassium, and other nutrients for delivery to the crops, or against leaching by rainfall.

Proteinaceousness vs. carbonaceousness in the crops–Plant growth is initiated by the reserve nutrients held in the seed. It is pushed forward by the fertility contributed by the soil. Plant mass increases as these contributions amounting to about 5 per cent of the plant come from the soil and serve to let the sunshine’s energy fabricate carbon dioxide from the air, and water coming via the roots, into the combustible part or the framework of the plant. This synthetic activity by light, or photosynthesis as it is commonly labeled, constructs sugars, starches, lignins, and other carbon compounds, mainly carbohydrates. Their physiological function in animal life is one of providing energy by their chemical breakdown through oxidation. Potassium is a catalytic agent and serves in their photosynthesis, but does not appear in their final form. This process of photosynthesis is the first step in all plant growth. It is readily recognized by the increase in plant bulk and is measured as tonnages per acre. It synthesizes the fuel values of the vegetation to give us fires when it is lignified into wood, but it serves for plant, animal, and human energy when as sugars–or starches converted into such–it plays the main role in the katabolic body processes for energy release.

Because of the emphasis on photosynthesis as a plant performance and the close association of tonnage increase of vegetation with the weather, we have given little or no thought to the synthetic performances carried on within the plant that are not directly prompted by sunshine energy. Animal growth and human body increase occur by their own anabolic activities. Dare we not believe that the plant carries on within itself similar activities whereby it gets energy by burning some compounds as a means to synthesize or construct others into complexities of its own characteristic creation? Cannot plants be more than simply a case of photosynthesis that delivers products of no greater elaboration than lignified cellulose or wood, and of no more value than that of energy delivered by oxidation or burning?

That plants do carry on elaborately complicated performances is attested by the fact that they synthesize the many recently recognized vitamins. These catalysts are still outside of the category of synthesis by animal life, even though by cooperating with the microbes–single celled lower forms of plant life–ruminating animals synthesize over a half dozen of them in their intestinal tract. Humans, too, produce at least one in that portion of our anatomy that is embryologically exterior to the body. Yeasts, that pass their existence in the darkness, and therefore do not indulge in photosynthesis, are significant forces for vitamin synthesis. Such chemical synthesis may well be called biosynthesis or synthesis by life in contrast to photosynthesis or syntheses by light.

Figure 2. Fertilizer treatments register their beneficial effects in the plant, but more noticeably in the physiology of the animal consuming it, as shown by better weight, wool, fur, bones and other body products and functions. Rabbit and bones on the left record the lack of soil treatment in contrast to the effects of soil treatment on the right for these herbivorous feeders.

 

Plants are carrying on these different biosyntheses, however, in magnitudes controlled by the soil fertility and not directly controlled by sunshine and weather as is true for photosynthesis. Here in these biosynthetic activities is the real service performed by plants for higher life. Here is the real control by which soil fertility determines the nutritive value of vegetation for animal and human life. Compounds of biosynthetic origin are not so simple nor plentiful as starches or sugars that are energy compounds. Rather they are the union of carbon, hydrogen and oxygen as basic photosynthetic compounds. Then by consuming a part of them for energy in the process, the nitrogen, phosphorus, sulfur, calcium, magnesium, and all the other soil-borne elements are synthesized into another part of them to give the building blocks and catalytic agents of growth of body rather than agents supplying only fuel. It is this biosynthetic use of soil fertility by plants that gives proteinaceousness, and the host of other possibilities in building and repairing the bodies rather than in providing energy to keep them running. Unless the soil fertility is available, plants are mainly photosynthetic and serve the latter function alone. Low supplies of soil fertility can still supply vegetative bulk or produce the factory structure. It requires delivery of soil fertility going through that factory, however, to give seed harvests and services in nourishing growing bodies of higher life. (Figure 2.)

Herbivorous vs. carnivorous habits according to soil fertility–The vegetative pattern of the United States as it is helpfully proteinaceous or deficiently carbonaceous determines whether wildlife is herbivorous or carnivorous in its feeding habits. This difference in feeds controlling the kinds of higher life forms is clearly illustrated by the nutritious grasses and other herbages of the western plains; the hard wheat of high mineral and protein contents of the prairies that becomes less so or more starchy and softer on coming eastward; the fattening corn in the eastern extremity of the prairies reaching into Illinois; and then the hardwood forests and finally the southern pines or other conifers in eastern and southeastern United States. It is no difficult mental struggle to carry the wildlife and domestic life pattern–to say nothing of human health pattern–across from west to east. With wildlife like the bison subsisting on herbaceous vegetation on the plains area can we not realize that the biosynthetic activities by the plants on those mineral-rich, unleached soils must result in animal diets that are almost complete in nutrient needs even though these are on herbaceous foods? Such diets provide not only energy in carbonaceousness for protective speed, but also calcium, phosphorus, proteins, vitamins, and all other soil-borne essentials and elaborations for muscle, bone, reproduction, and all other body parts and processes for maintenance of the species. When wildlife survival is so closely connected with the soil, certainly the soil fertility must be ample in both kinds and amounts of the dozen chemical essentials for life. It is these same soils on which man lives sufficiently and almost completely on an herbaceous basis by means of hard wheat. Bread from such soil fertility products can really be called the “staff of life.”

Higher rainfalls in eastern and southeastern United States present a pattern of different kinds of wildlife, drawing not so directly from the soil the dozen chemical elements needed. More processes, more elaboration and more interventions of different life forms are necessary to collect and pass on all they must have to survive. They are farther removed from the soil in their nutrition when they roost, or run about, in the treetops. Seeds, as the reproductive insurance effort by the plant and as a smaller part of the whole plant into which there are concentrated the biosynthetic products of a season’s collections, are needed for animal survival. The terminal buds into which the soil fertility is concentrated by means of translocation from the lower leaves and limbs of the plants are the only plant parts taken as browse. Animals of herbivorous habits are few per unit area, and then they are characterized by shyness, slender bodies, and high speed, more than by boldness and vigor for fight. It is no stretch of your imagination to supply illustrations of wildlife pointing to contrasts resulting between the more fertile soils of the West and the less fertile soils of the East and South.

Should we carry the wildlife pattern into the much more highly leached soils of the humid tropics, the prominence of carnivorousness of land animals–to say nothing of it for aquatic forms–will immediately emphasize itself. The law of the jungle and its dense tropical forest vegetation has always been “the law of the tooth and the claw.” Each life form that survives must use the soil fertility collecting efforts and synthesizing processes of not only plants but also of other animals to assemble and deliver the dozen essential elements in nourishing forms to guarantee its survival. It is only through these circuitous routes of consuming other life forms that the animal reaches over enough territory to provision itself for existence on the soils that are so infertile relative to higher life but seemingly fertile if judged only by tonnages of woody vegetation.

The pattern of life, natural or managed, must fit pattern of soil fertility; parallel then with soil construction and soil destruction as outlined by the increasing forces of rock weathering in Nature, there are the variations in chemical composition of the vegetation from proteinaceousness to mainly carbonaceousness. Likewise there are the wildlife forms and habits that go from the herbivorous to the carnivorous. When this pattern of thinking about wildlife as it can feed itself is fully understood according to the premise of soil fertility on which it rests, then the places favorable for different kinds of wildlife will be readily recognized as specific locations on the map according to soil fertility. Then, too, the efforts in management of wildlife will not be a matter of political appeasements to payers of hunting license fees by planting wildlife artificially in haunts preferred by the hunters. But rather it will be one of making wildlife natural by feeding it naturally through the soil. It will be one of educating the people to the appreciation of the soil as the basis of all life in terms of soil fertility.

Let us hope that a few of the broader general principles here set forth will stimulate the continued wildlife research to collect more facts and establish still more principles which will make conservation of soil, of wildlife, and of all other life, not the responsibility of professional and employed commissions alone, but the responsibility and privilege of each and every one of us as citizens of a great democratic country.

 

References Cited:

Albrecht, W. A.: 1943. “Soil and livestock.” The Land, 2:298-305.

Bogart, Lotta Jean: 1943. Nutrition and physical fitness. W. B. Saunders and Company.

Bogart, Ralph: 1944. “Loss of pigs.” Mo. Agr. Exp. Sta. Farm News Service, 33, No. 26.

Powell, Elmer B.: 1944. Private correspondence