Jardine W M
Identification and determination of the causes of destructive plant diseases and the development of methods for their control, have done much to add safety to agricultural practice. This work is, obviously, based on fundamental research in plant pathology.
Research in the field of soils involves physics, chemistry, biology and soil classification. The aim of the physicist is to make the soil a more efficient medium physically for the growth of plants. The business of the chemist is to determine the chemical nature of soils and to insure that the plants grown in the physically efficient soils are supplied fully and cheaply with the nutrient elements required for the best growth. To the soil bacteriologist the farmer looks when he wants to be sure that his soil will grow a particular kind of legume, and to him the farmer has not looked in vain, for science has made it possible to inoculate soils by means of pure culture of nodule organisms.
The investigators in pure soil science are engaged in identifying individual soils and in classifying and mapping them. In this field of endeavor the United States is far in the lead of other countries, owing to the untiring efforts of Dr. C. F. Marbut, Chief of the Soil Survey. The Soil Survey is the only scientific institute which gathers facts about soils of the whole country and shows their relationships. It has taken numberless centuries for men to realize that individual soils exist, and that the first step toward understanding them is to classify them.
Enormous aid has been given to agriculture through minute research dealing with insects that prey upon crops or livestock. Among the lines undertaken in parasitology is the investigation of the life histories of parasites. Much attention has been devoted to this by the Department of Agriculture.
For example, the Texas fever tick was found to pass its entire life from the seed tick to the engorged adult on a single host animal, and hence it was found possible to eradicate ticks by dipping cattle alone which would be a much less adequate procedure if the ticks passed parts of their life cycle on other host animals as many ticks do.
The sheep stomach worm was found to ascend grass blades in the presence of moisture. This discovery directed attention to the danger from wet pastures and short grass. The parasite was found to reach the egg-laying stage in the intestine in about three weeks, leading to a recognition of the necessity of moving sheep to clean areas or else treating them every three weeks to prevent reinfestation.
Valuable studies have likewise been made in the correlations between the chemical composition and water solubility of anthelmintics and the value of these drugs in removing worm parasites.
A consideration of the chemical composition of chloroform as indicating that its value against hookworms was due to its chlorine content led to the development of carbon tetrachloride, a related compound, as an anthelmintic for use against hookworms. Since 1921 this has been generally used in veterinary and human medicine. It has been found of value against many kinds of round- worms in animals and has recently been found to be effective in destroying liver flukes in sheep, being the cheapest of the effective preparations known for this purpose.
Pursuing the same line of investigation resulted in the discovery that tetrachlorethylene, another related compound, is equally effective against hookworms and is apparently safer. Further studies are being carried on with a view to developing from a chemical basis a drug which will be of value in removing several sorts of worm parasites not at present susceptible to satisfactory treatment with any one drug. It has been ascertained in connection with these investigations that the water solubility is a factor of importance and that there is a point of optimum solubility which is approximately known at present.
The intimate structure of injurious insects, their physiology, their ecology, and their various reactions are being minutely investigated.
These investigations have in many cases led to practical results. A very recent one relates to the Japanese beetle, an accidentally introduced pest which threatens great damage to American horticulture. Investigations of the olfactory sense of this species have led to the discovery of a chemical attractment that makes possible ready destruction of the adult beetles in great numbers.
Animal industry has profited greatly from the application of science to its problems. The importance of the vitamins and of light to the growth and development of animals is recognized by all. The significance of vitamin E, and possibly a vitamin which has an influence upon lactation has not so far been generally realized in applications to the industry.
The importance not only of the quantitative distribution of foodstuffs, but of the qualitative character of the constituents of an animal ration, has been discovered from investigations in both general and animal physiology in addition to direct studies of nutrition. Knowledge of the importance of an adequate supply of protein of a good qualitative character, and of the nature of the deficiencies of certain proteins, has been derived from reciprocal relations between studies in pure chemistry and in nutrition.
Our understanding of the gross nutritive requirements and the relation between the character of food and the production of work has been drawn from the fields of physics and physiology and applied through calorimetric studies on animals themselves. As the advances in animal nutrition are examined it is found that there always has been a close relation between studies in fundamental sciences, particularly those of chemistry, physiology and physics, and the final application of the principles developed to farm practices.
Destructive animal diseases have been brought under control by scientific means. Blackleg and hog cholera, for example, are now preventable at a merely nominal cost for vaccines.
The importance of meteorology to agriculture was early recognized here at Yale University, where Elias Loomis, who was professor of natural philosophy and astronomy from 1860 to 1889, became recognized as the foremost meteorologist of the United States.
As a result of research in this field, our climatology is now known, and it is possible to state where this or that crop can or can not be grown successfully. The relations of the yields of various crops to the prevailing weather conditions at their several stages of growth have been studied, and in many cases helpful estimates of yields can be made weeks and even months before harvest.
The duration and intensity of sunshine are of great importance to all varieties of vegetarian, but very unequally so. Similarly the spectral quality of the light likewise is of great importance, not alone to vegetable growth but also to animal health. Studies of these relations are just beginning a field of investigation that offers endless opportunities in pure science, and promises significant practical applications.
The applications of science to agriculture are important not only in production but in marketing a field which is growing rapidly in significance to the farming of this country.
Pure science has a direct relation to the marketing of grain, notably wheat. The protein content of wheat has played an increasingly important part in the price paid for this grain at the large terminal markets during the past few years. The State of Minnesota maintains fully equipped chemical laboratories at Mineapolis and Duluth. Every car of wheat received at these markets is tested for the protein content and certificates covering the protein content of the wheat are issued by the State.
The State of Kansas and the State of Missouri maintain a chemical laboratory at Kansas City for the same purpose. At other important terminal markets where wheat is received in large volume chemical laboratories are maintained by either the State or the local grain exchange. In addition many commercial chemists find a field for business in determining protein content of wheat.
This direct application of the pure science of chemistry to grain marketing is a comparatively new development. There is much room for it to expand still further. For example, the protein test now applied is for the purpose of determining the quantity of protein which wheat contains. The quality of the protein is fully as important to the miller as the quantity. Up to date, however, no reliable, satisfactory method has been developed for determining the quality of protein in wheat. The development of such a test would probably revolutionize the system of buying and selling wheat in much the same way that the Babcock test revolutionized the dairy industry.
In considering the interrelationships of prices, marketings, supply, plantings, breedings and other questions, there is being developed a scientific approach in order to obtain quantitative answers. We are no longer satisfied, for instances, with the knowledge that bumper crops depress prices, or that low-priced feeds cause farmers to produce more livestock. We want to know the effect on price of a large crop (in dollars and cents), and the exact number of pounds or the number of head of meat animals which will be forthcoming as a result of given feed prices.