Economic Botany
Man's dependence on plants for the essentials of his existence has been of paramount importance in his life since the human race began. Primitive man probably had few needs other than food and a little shelter. Civilization, however, has brought with it an ever-increasing complexity, and has increased man's requirements to an amazing degree. The man of today is no longer content merely to exist, with food and shelter as his only wants. He desires other commodities as well, and raw materials that can be converted into the many useful articles and products which contribute to his enjoyment of life, and which incidentally increase his debt to plants.
The three great necessities of life-food, clothing, and shelterand a host of other useful products are supplied in great part by plants. An adequate food supply is, and always has been, man's most outstanding need. In the last analysis all his food comes from plants. To be sure he may eat the flesh of animals, but these lower animals are just as dependent on plants as man himself, and they are equally unable to manufacture any of their food from raw materials. Clothing and shelter, the other prime necessities of life, are derived in great part from plant fibers and from wood. Wood is one of the most useful plant commodities in the world today, and it played an even greater role in the past. Aside from its use as a structural material, wood is valuable as a source of paper, rayon, various chemicals, and fuel. Other types of fuel, such as coal and petroleum, make available for man the energy stored up by plants that lived and died ages ago. Drugs, used to cure disease and relieve suffering, are to a great extent plant products. Industry is dependent on plants for many of its raw materials. Cork; tanning materials and dyestuffs; the oils, resins, and gums used in making paints, varnishes, soap, and perfumes; and rubber, one of the most outstanding materials of modern civilization, are but a few of the valuable products obtained from plants.
Aside from their value as sources of food, drugs, and many of the raw materials of industrialism, plants are important to man in many other ways. The role of colorless plants in the economy of nature; the part that bacteria play in disease and many industries; and the effects of forests and other types of natural vegetation in controlling floods and erosion are but a few examples. The aesthetic value of plants has no small influence on man's enjoyment of life, as evidenced by the host of garden enthu"iasts and flower lovers.
The production and distribution of plant products have a profound influence on the economic and social life of the nations of the world, affecting both domestic conditions and international relations, and even changing the course of history. It will not be possible within the limits of the present volume to consider the many aspects involved and their fundamental bearing on human affairs and activities. A few examples, however, may be permitted by way of illustration.
The maintenance of an adequate supply of food and raw materials for the use of industry is essential to the existence, as well as the prosperity, of any nation. Few countries are independent in this respect, with the result that foreign trade, with its many ramifications and consequences, plays a necessary and important part in the life of the world. When the population of a country is small, the problems involved are not very great. Most of the civilized nations, however, not only have a large population, but one that is entirely out of proportion to the country's ability to produce the necessities of life. This tendency to overpopulation in excess of the maximum possible production of food and raw materials is responsible for many of the difficulties and problems that harass the modern world, especially in the caSe of nations with a restricted land area. The necessity for finding an outlet for their excess population, which all too often is steadily increasing, and the desirability of adding to their domestic supply of commodities have been responsible, in great part, for the policies of aggression that many such countries have pursued in recent years. The story of Japan in Korea and Manchuria and of Italy in Ethiopia and the current increasing demand in Germany for the restoration of her colonies are cases in point.
In recent years various economic problems concerned with agriculture have become increasingly important in the United States, and in other countries as well. These have served to bring home more clearly than ever before the intimate relationship between plants and human welfare.
One of the most serious of these agricultural problems is concerned with overproduction, a condition that has frequently arisen in the history of agriculture. Whenever a large supply of any commodity is available for the market, it usually results in lower prices, which often fall below the figure at which a profit can be realized. A particularly serious case of overproduction had developed in the United States in 1929 when the failure of foreign markets and the low buying power at home combined to cause the piling up of a huge surplus of agricultural products. The lowering of prices which followed created such a great discrepancy between the cost of production and the prices received for the products that the farmers were threatened with wholesale bankruptcy and the welfare of the entire nation was impaired. The efforts of the government to deal with this problem through crop reduction, crop adjustments, and other means are familiar to all. It has been estimated that from 1928 to 1932 some 12,000,000 to 15,000,000 more acres were under cultivation than were necessary to supply all the demands for farm products, both at home and abroad. If this is the case, an obvious method of combating overproduction would be to remove some of these unnecessary acres from cultivation.
Another agricultural problem concerns the proper utilization of the land, and this is related to characteristics inherent in the plants themselves. The successful pursuit of agriculture in any area depends on the presence of certain environmental factors that are necessary for the particular crop concerned. Each species differs in its soil, moisture, temperature, and other require- ' ments. Satisfactory growth and development can take place only if all these factors are present in proper amounts. This fact has often been ignored and agriculture has been carried on in regions utterly unsuited for crop production, particularly on a commercial scale, with consistently unsatisfactory yields and low financial return as the inevitable result. To remedy this situation, the retirement of these submarginal lands, as they are called, from agriculture has been advocated. This would make possible the utilization of the areas for forests, grazing, wild-life conservation, and human recreation, and at the same time would contribute to crop reduction. The resettlement of some of the farming population, which accompanies the abandonment of agriculture in such areas, obviously has a profound effect on human activities.
Still other agricultural problems are physical, rather th,an economic, in nature, and are concerned more with productivity than production. The practice of farming necessarily brings about the destruction of the natural vegetation, which has a protective function; this induces conditions that result in the deterioration of the soil. This deterioration may consist of the exhaustion of the mineral nutrients, which is not a serious matter since it can be compensated for by the use of fertilizers, or it may comprise the permanent loss of soil through erosion. Erosion is caused primarily by the action of water and wind. In the case of water, two types of erosion are produced-sheet erosion and gully erosion. In the former a thin sheet of soil is gradually removed from slightly sloping fields. The process is hardly noticeable and, although widespread, it is not very destructive. Gully erosion, on the other hand, is brought about by the concentrated runoff of water and, where conditions of slope and soil are favorable, results in the formation of deeper and deeper gullies, which eventually render the area unfit for agriculture for all time. Several million acres in the Southern states have been made worthless as the result of this type of erosion. If it is allowed to continue unchecked, its results may be so serious that human life is rendered impossible and barren deserts are the outcome. This has been the case in many parts of China.
Wind erosion is always more or less active on loose and sandy soil, and it is greatly increased as the result of cultivation and overgrazing, which tend to deplete the moisture-containing humus and pulverize the soil. The growing of cereals, which require constant cultivation, is especially likely to bring about conditions that favor both wind erosion and water erosion. The serious situation that has developed in recent years in the semiarid regions of the Great Plains is a case in point. Even though the district was unsuited to the purpose, extensive areas of thf' natural grassland vegetation were plowed up and planted to cereals. The breaking up of the soil and the unusual drought that occurred over a period of several years combined to make conditions exceedingly favorable for wind erosion. This was responsible for the great dust storms that have prevailed in the area and brought widespread destruction in their wake, not only wearing away the soil in some places, but depositing the eroded material on fertile ground elsewhere, thus rendering countless additional acres unfit for agriculture, and perhaps for human habitation for many years to come. It is essential that some sort of soil conservation be put into practice before it is too late. The policies involved in soil conservation include the preservation of soil fertility, the prevention of erosion, the promotion of better land utilization, the stabilization of eroded areas, and various types of crop adjustments.
Plants have been and still are responsible for many of the social ills that beset mankind. In times past the exploitation of workers in various fields of activity concerned with plants has had serious consequences. As examples may be cited slavery, which went hand in hand with the production of cotton in the southern United States; the cruel treatment of the native rubber workers in the Belgian Congo, which shocked the entire civilized world in years past; and more recently the plight of rubber collectors in Brazil.
At the present time the problem of the migratory farm laborer, the share cropper, and the working conditions of farm labor in general are much in evidence.
Perhaps the chief social problem for which plants are responsible is the narcotic drug habit and the illicit trade that has grown up around it. This constitutes one of the most serious aspects of our modern civilization.
The comments made in the foregoing pages, inadequate though they may be, may perhaps serve to give some idea of the many ways in which plants and plant products affect the welfare of mankind.
