Better Soils, Better Food

by KENNETH C. BEESON

NUTRITION begins with the soil. The truth of that statement has been investigated only recently, but it has long been a factor in the thinking of men. Charles A. Browne in his recent book, A Source Book of Agricultural Chemistry, has organized in an interesting way the evolution of the concept from the time of Democritus ( about 360 B. C. ) to Liebig (1803-73).

Democritus, for example, suggested a cycle of indestructible elements from the soil to the plant and to the animal and back again to the soil. Aristotle (384-322 B. C.) taught that plants absorbed through their roots the necessary material for their growth. In turn, bones, blood, milk, hair, and other parts of animals were derived from constituents of the plants. But long before these speculative ideas began to take form in the minds of men, the practical farmer had observed that his animals responded differently to forages from different localities. Through experience he had learned not only what localities were best suited to his needs but he had learned that some were definitely undesirable.

The nutritional problems of animals in relation to soil conditions, however, did not become acute nor were they the subject of scientific inquiry until nearly the middle of the nineteenth century, when their importance was emphasized as the increase in world population was Pushing man out into new lands. Many of the new lands were found to be incapable of supporting animal life, particularly when the animals were not permitted to graze large areas and select their food. The need for new lands has continued to create problems of this nature that must be solved. There are still vast areas in the world, and in the United States in particular, that will be suitable for many agricultural purposes when it is learned how to correct their natural shortcomings.

Troubles in grazing animals, related to deficiencies or to toxic quantities of mineral elements in soils, have been recognized in the United States for more than 50 years. Many of the ailments have been investigated extensively. A deficiency of phosphorus in soils and forage was among the first to be recognized and described.

More recently an appreciation of the role of the trace elements or micronutrient elements, such as cobalt and copper, has developed. They occur in soils in minute quantities. An acre of topsoil, 1 foot deep, for example, ordinarily contains less than 20 pounds of any micronutrient element. A ton of hay normally contains about 2 grains, or one four-thousandth of an ounce, of cobalt. Where such small quantities are involved, an understanding of their importance was not realized until the refinement of laboratory methods made such studies possible.

It is evident that a deficiency of phosphorus, next to iodine, is the most widespread of any mineral nutritional trouble in grazing animals. Recent work has emphasized that phosphorus may generally be deficient in virgin soils throughout the Atlantic and Gulf Coastal Plains, a fact that becomes apparent as more and more of those undeveloped lands are used for profitable grazing. John Foster, of the North Carolina Agricultural Experiment Station, for example, has stated that the raising of beef cattle is rapidly assuming an important place in the agriculture of the Coastal Plain, where the available forages appear adequate for the protein and energy requirement of the animals, but that limiting factors seem to be deficiencies of phosphorus and possibly some micronutrient elements, such as cobalt.

Deficiencies of phosphorus were observed many years ago in the Coastal Plain regions by investigators in Florida, Alabama, and Texas. The work of W. H. Black, J. M. Jones, and their co-workers in southeastern Texas is one of the more recent contributions to the solution of the problem. According to them, an abundance of vegetation is available in that area. Consequently, there are greater numbers of cattle there per section than in any other range area of the State. The fact that a nutritional deficiency does exist is evident from the small size of the animals, reproduction failures, and malformed bones that are easily broken, and a persistent craving by many cattle for bones, dirt, wood, and other materials.

In Tennessee there is a recognized relationship between the supply of phosphorus in the soil and the health and production of animals and the economic status and well-being of the people. In few parts of the country are the contrasts between good and poor soils more striking. The reason lies in the fact that in Tennessee some of the best agricultural soils of the East are closely associated with much less productive and often actually deficient soils.

Conditions in Minnesota and Montana are probably fairly typical of the Northwest. In Minnesota much has been done in locating deficient areas, and experiments designed to correct the troubles are now under way. The work in Minnesota has emphasized the study of the effect of superphosphate over a large part of the State. Much more work is required to demonstrate the practicability of this on the more extensive range areas farther west.

Since 1937 the importance of cobalt in animal nutrition has been repeatedly demonstrated throughout the world. Several areas in the United States are now believed to have soils deficient in it. One of the most extensive is in the Northeast, where the problem is being studied by men at the New Hampshire Agricultural Experiment Station.

In troubles of this kind it is hard to establish a definite relationship from the soil to the animal, but it has been demonstrated in New Hampshire that ailing animals respond to administrations of cobalt, that the largest proportion of the farms involved occurs on soils developed on materials derived principally from granite, and that there are definite and significant differences in the cobalt content of the forage from good and poor areas. In some cases, however, the cobalt content of poor hay is not acutely low, as measured by the rather uncertain standards that we have.

Troubles in grazing animals due to a lack of cobalt have been known to the scientists in Florida for some time. The situation there (where the first research of this kind in the United States was done) emphasizes that multiple deficiencies may often be encountered. Thus, cobalt and phosphorus, cobalt and copper, or copper and iron have been noted as being simultaneously deficient in forages in those areas. Recognition of this possibility may be helpful in explaining discrepancies in the known facts associated with other trouble areas of the country.

Deficiencies of cobalt have been reported from Michigan and Wisconsin; possible deficiencies have been reported from eastern Pennsylvania, Cape Cod, and northeastern New York. Most of these areas have not yet been studied in sufficient detail to permit generalizations as to the soil, plant, and animal relationships.