Some progress is being made. As the plant grows and develops, many complicated and intricate chemical reactions occur. From relatively simple compounds they produce the complex proteins, the carbohydrates, and other components of food and feed. An example would be the formation of protein from the simpler amino acids.

Experiments in the Department of Agriculture have shown that in cases of a deficiency of a mineral nutrient, these reactions sometimes slow down or fail altogether. Thus, in a plant growing in a soil deficient in potassium, magnesium or manganese, for example, certain amino acids tend to accumulate as such in the plant instead of building up into proteins. The nutritional importance of this point is still to be demonstrated, but the implications are that here is a suggestion for the differences found in the nutritional quality of the forages I have described.

CLIMATE is a factor of great importance in the production of crops of high nutritional quality. Crops grown on two different soils in two climatic regions differ in nutritional quality. Experiments carried on in the Department of Agriculture nearly 50 years ago demonstrated the predominant effects of climate in influencing the nature of protein. Research workers in a group of Southern State agricultural experiment stations have advanced our knowledge concerning the relation of climatic factors to both the organic and mineral components of plants.

The farmer cannot adjust temperature, sunlight, wind movement, or humidity to suit his needs, but in many situations he can supply water when necessary. At various times some effort has been made to evaluate the effects of water on nutritional quality.

Such effects must be profound. Yet to isolate moisture supply and determine the magnitude and direction of its influence has proved to be exceedingly difficult, and few generalizations of value have been discovered. For example, moisture has marked effects on the growth of plants and on the solubility and mobility of the plant nutrients in the soil. No specific recommendations can be made, however, concerning irrigation except as it is required to produce normal yields of food and feed crops.

THE METHODS OF HARVESTING, curing, and storing crops can preserve or destroy most of the effort for better nutritional quality that has gone into their production.

There is no need here to dwell at length on such well-known practices as the best time for harvesting hay. Innumerable reports from the agricultural experiment stations have shown that in the prebloom stage, forages are higher in protein, retain their color better in curing, and hence have a higher nutritional quality than forages harvested in the postbloom stage.

Other practices that preserve nutritional quality include the curing of hay without subjecting it to excessive weathering and techniques that allow the retention of leaves. The latter factor is of great importance, because a high proportion of the protein, vitamins, and minerals is in the leafy tissue.

Management of the potato crop is an example of the effects of time of harvest and storage on quality. The potato is an excellent source of vitamin C, which is essential in the human diet. The vitamin C in the potato tuber increases as the plant matures. As soon as the vine dies, however, the tuber is essentially in a storage condition in the soil. The longer it remains in the soil, the less vitamin C will be found in the potato. That is exactly what happens if the potato is harvested and put into artificial storage, in which, however, some measure of control can be exercised, and more of the vitamin C is preserved.

THE MANAGEMENT OF SOILS that contain toxic amounts of some mineral elements has in no case been clearly defined, but certain simple remedies are known and have been used to counteract some of these toxicities. The basic causes of such troubles must be investigated before sound recommendations can be made.

Selenium toxicity in vegetation in some places in the West is an example of this type of problem. An adequate mapping of the critically toxic areas will provide information necessary for fencing the affected soils. Grazing would be prevented in such areas, but fiber and seed crops could be grown there. Overgrazing of seleniferous areas should be avoided. It is a common observation that cattle will not select the selenium accumulator plants the plants that tend to absorb and store excessively large quantities of selenium if other forage is available. Finally, a small amount of arsenic given through the drinking water or in the salt will counteract the effects of selenium. No effective soil treatment in seleniferous areas has been devised.

Soils supplying excessive quantities of molybdenum to plants present similar difficulties. The known remedy, doses of copper sulfate (blue vitriol), is applied directly to the animal. Some control in pasture and forage can be applied through soil management by eliminating legumes from the forage mixture. On the same soil, legumes will absorb and store 2 to 10 times as much molybdenum as will associated grasses. Here, again, no effective soil treatment has been devised.

MUCH HAS BEEN SPOKEN and written about the occurrence of nutritional troubles and other diseases in man and impoverished soils, leached soils, eroded soils, "wornout" soils.

The truth of these relationships is difficult to deny but confirmation is almost impossible to achieve.

The fallacy of the claims lies in the generalizations that have been made. The reason for this lies obviously in the almost insurmountable complications attendant upon longtime experiments with human subjects.

Isolated communities dependent on their own produce might supply the answer, but in the United States few such communities are available for study. Furthermore, it has not been possible to separate economic and other circumstances from soil conditions as causes of poor nutrition in such communities.

Any sensible approach to the problems of soils in relation to human nutrition must therefore be indirect.

Management practices that produce ample supplies of crops containing maximum amounts of vitamins and minerals will have an influence on human health and welfare. Management practices aimed at the production of better feed for animals thus supplying the market with animal products such as meat, milk, and eggs also will help improve human nutrition. An example: The localities where it has not been practical to keep a family cow because of a deficiency of cobalt or possibly copper or phosphorus in the soil could easily be made suitable for cows. I know of few ways better than this to raise the standard of living of some farm families.

An effective system of soil management will aim to provide food and feed crops with an optimum level of all nutrients required by animals and man. Such a system will seek to avoid upsetting nutritional balances simply to provide greater yields. It will be based on the best information available as to all of the requirements for good yields and good nutrition.