The supply of food depends on three factors: how much has been produced by agriculture and fishing (see \Tfishing industry\t); how much has been consumed; and how much has been preserved by safe processing and storage (see \Tfood technology\t). The most important agricultural products for the world's food supply are cereals (\Lgrain\ls), pulses, and, to a lesser extent, livestock (see \Tanimal husbandry\t). Cereals, such as wheat, rice, maize (corn), millet, and sorghum, provide nearly all the food energy (calories) and up to 90% of all protein consumed by the world's people. Pigs are the chief meat animal worldwide, followed by poultry, beef cattle, and sheep. Pulses--the seed parts of such legumes as dried beans, soybeans and peanuts (groundnuts)--are important sources of protein in the world food supply. Except for sugar and bananas, few of the other crops that are prominent in the world agriculture trade have nutritional significance in the food supply. Many fruits, grains, and vegetables that are often unfamiliar to Western agricultural scientists, however, serve as important local food supplies. Supply and Population About 90% of all grain produced is consumed in the countries where it is grown. The 10% that enters world trade comes from the few countries--the United States, Canada, Australia, and Argentina--where the grain produced far exceeds domestic needs. Most countries depend to some extent--and developing countries tend to depend heavily--on cereal imports to augment their own crops. Some authorities predict that \Tpopulation\t growth will eventually surpass world food production and that massive \Tfamine\t will result--a theory first proposed by the British social philosopher Thomas \TMalthus\t. Other authorities, who point to a recent decrease of population growth rates as well as to dramatic gains in agricultural production, insist that such a tragedy can be prevented by a combination of appropriate governmental policies and appropriate research and technology. Effective Demand Both high population growth and the effects of a minority of the world's people having the money to consume more than they need can cause stresses in the food supply. Persistent \Tpoverty\t, however, is the underlying cause of the world's hunger problem because in many places the ability to obtain food is determined by income and purchasing power no matter how large the supply may be. People or governments without enough purchasing power lack what is called effective demand for food in the marketplace. Many governments find it necessary, therefore, to protect the nutritional needs of their own low-income populations, and sometimes those of others, with special programs. The most extensive food-aid program undertaken is the Food for Peace program conducted since 1954 by the U.S. government. Through this program, U.S. surplus grain either can be sold to developing countries at normal market prices with the aid of low-interest loans or can be distributed at no charge by such organizations as Catholic Relief Services or Cooperative for American Relief Everywhere (see \TCARE\t) to developing countries faced with food emergencies. Efforts have also been made to avoid harming agricultural development in countries that receive food aid. Sometimes the laws of effective demand hurt the poor in unexpected ways when traditional agriculture in developing countries is modernized and brought into the international market system. When India's farmers, for example, began tofind wheat and rice production more profitable than before the green revolution, they lost interest in traditional pulse production. As pulses became less plentiful in the local markets, their prices rose. Malnutrition increased because the poorest could no longer afford to balance their incomplete grain-protein diet with pulses. FACTORS AFFECTING FOOD SUPPLY Basic farming practices (see \Tfarms and farming\t)--planting, harvesting, and storage of crops--are generally similar everywhere, but various systems of farming exist. In many developing nations much of the cropland is currently devoted to subsistence agriculture, a food-production system characterized by minimal mechanization, high reliance on human labor, and mostly on-farm consumption of what is grown. About 60% of the world's cropland is estimated to be in subsistence agriculture. Another form of food production, particularly in North America, Europe, Central America, and Oceania, is commercial agriculture, which is large-scale, highly mechanized, and entirely market-oriented (see \Tagribusiness\t). A third important system is that characteristic of centrally planned, or socialist, nations. These systems include state farms and \Tcollective\t \Tfarms\t, as in the \TUSSR\t, and communes, as in China. In general, these systems are designed to provide food for the workers on the farms in return for their labor and also to provide food for the nation as a whole according to a national plan. Arable Land Agriculture depends ultimately on arable land--land that has the potential to produce a crop. About 3.2 billion ha (7.9 billion acres) of arable land exist worldwide, which is about 24% of the total ice-free land. Currently, less than half of the Earth's arable land is actually under cultivation. The largest reserves of unused arable land are located in Africa, where 72% of the arable land is not used for crops. Huge investments would be necessary to do the clearing, leveling, disease control, and irrigating required for much of this land to become fully productive. Consequently, many concerned authorities believe that efforts to improve agricultural production should focus on currently cropped land. As demand for food has increased, land and \Tsoil\t mismanagement has occurred with alarming frequency. In the past 100 years in parts of the American Midwest, more than 50% of the topsoil has been lost to wind and water \Terosion\t through improper cropping and tillage practices. About 1 million ha (2.5 million acres) of cropland are lost each year in the developing nations, due mostly to poor land management. Overgrazing and deforestation of land has occurred in such areas as Mexico, Malaysia, and the Sahel. Arable land may be turned to \Tdesert\t by the combined effects of destroyed vegetation and erosion. Arable land in urban and suburban areas worldwide has also been lost by conversion for housing and business purposes. Such loss of prime agricultural land in North America--more than 600,000 ha (1,482,600 acres) a year--is especially serious, and this land can only be replaced by bringing less productive, or more erosion-prone, land under cultivation. Efforts are now being made by a number of states in the United States and also by governments of other wealthy nations to preserve their best remaining agricultural land. Water Supply Many experts now believe that in the remaining years of the 20th century lack of water (see \Twater resources\t) rather than lack of arable land will be the major obstacle to expanded worldwide food production. As with land, the amount of water available for agricultural use cannot easily be increased, but it can be better used. The total volume of all water on Earth is estimated to be 1.46 billion km(3) (350.3 million mi(3)), but of this only 0.004% of all water is present in the soil and subsoil, only a fraction of which is currently cultivated. An additional 0.32% of the Earth's water is present in groundwater reserves and freshwater lakes, which can make a contribution to agricultural demands. The remainder is either too salty for agricultural use or is permanently frozen and inaccessible, and these resources are not evenly distributed. Research is now being done in the areas of \Tirrigation\t, seawater \Tdesalination\t, and \Tweather modification\t to improve water availability and thus increase the amount of land that can be farmed. Climate and Weather Climate, the long-term atmospheric conditions of a region, determines the cropping possibilities in an area. Rice grows in a wet, tropical climate, for instance, and corn grows in a humid subtropical or temperate climate. Weather is the daily expression of climate and can change greatly from day to day or seasonally. Weather patterns may occasionally set limits on agricultural productivity, even in generally favorable climates. Recent famines in India and China can be traced to such erratic weather patterns as high (causing floods) and low (causing \Ldrought\ls) precipitation in climate zones that otherwise would be expected to produce successful crop yields. Climates, although relatively stable, also change. In the Northern Hemisphere, for example, climatic patterns appear to be becoming more extreme, which may cause serious agricultural disruption. Fertilizer Because soils often lack the right kind and amount of plant nutrients for the best crop results, the farmer must supply such missing nutrients. In many parts of the world, fertility needs are met by the use of inorganic chemical \Tfertilizer\t. For developing nations, however, the cost of such fertilizer is often too high. Less than 20% of the world's inorganic fertilizer supply is used in these countries. Organic sources of plant nutrients are widely used to increase soil fertility in subsistence farming in the developing nations where inorganic chemical fertilizers are scarce or too costly. Even the efficient use of these materials, however, fails to substitute fully for the boost in crop productivity yielded by chemical fertilizer. Pests Once a crop has been established, the farmer is immediately threatened with crop losses from a variety of pests. Annual losses due to pests amount to 20%-40% of potential production, and the crops destroyed by pests each year are worth about $30-80 billion worldwide. In developed nations, pests have been controlled by chemical \Tpesticides\t--particularly \Lherbicide\ls, for weed control--and insecticides. Chemical pesticides, however, can cause ecological damage and present hazards to human health. Increasingly, chemical pesticides and their hazardous potential are being introduced into developing regions of the world. Appropriate pest-control strategies, however, are able to replace the exclusive use of chemicals and include a combination of crop breeding for genetic resistance to specific pest problems and other management practices that create environments unfavorable to pests. Energy Increased food productivity is related to increased use of energy. In the developing world the major source of power for agriculture continues to be human labor and animal power. In developed nations, power is supplied by agricultural machinery that is fueled largely by petroleum. Much energy is also consumed in irrigation, transportation, food processing, and the manufacture of agricultural chemicals and fertilizers. One effect of such modernization is that fewer people can produce greater quantities of food. A point of diminishing returns can be reached, however, where adding more energy to agricultural processes becomes an inefficient use of that energy. In mechanized agricultural systems, as much as 10 times more energy is used to produce food than is returned to society as food for consumption. In many developing nations, however, energy invested in agricultural production generally returns up to 20 times more in food products than is expended during production. Nevertheless, developing nations, in order to most fully utilize their food potential, will have to apply much more energy than previously to agriculture, especially in the areas of improved tillage, more fertilizer, and timely harvesting. Alternative energy resources are drawing increased attention as fuel from conventional sources becomes more costly and less available. One alternative is to manufacture gasohol, which is a combination of gasoline and alcohol from plant materials, particularly grain. The use of grain as fuel is controversial because that grain could be used as food. Some people conclude that strong efforts at petroleum conservation would better meet the demand for energy security than the use of such costly and untested synthetic fuels as gasohol. INCREASING FOOD PRODUCTION As world population grows, the productivity of the world's cropland must increase rapidly to maintain the minimal supplies currently available in many developing nations. If standards of living in developing countries are to be raised beyond subsistence level, the increase in food production must exceed population growth in those countries. Land Reform In many parts of the world--particularly in Latin America--the distribution of land is grossly inequitable, with small minorities of wealthy landowners controlling major portions of the best agricultural land. Often these landowners focus on the production of cash crops for the export market. Poor subsistence farmers are forced to farm small plots of marginally productive land to provide for their own needs. The need for reform of land-tenure patterns is apparent in these situations, but land reform is a political issue; often those with the power to direct such land-reform policies are the very people who stand to lose land. Consequently, land-tenure patterns tend to change slowly. Governments of several nations have experienced some success with land-reform programs. Generally, these programs provide poor farmers with secure access to agricultural land through such policies as rent control for tenant farmers or direct expropriation and redistribution of large land holdings. Increased employment opportunities in the rural sector of the economy, increased land productivity, and a rise in the standard of living have resulted but are dependent on the small farmers' access to credit, education, and other government support services coupled with land reform itself. Use of Machinery In the more affluent nations, large-scale mechanization of agriculture has increased the amount of food that can be produced by each worker in agriculture and thus has reduced the need for labor and the number of on-the-farm jobs. In many DCs, however, where labor is plentiful and incomes often desperately low, governments now seek "appropriate" technologies that are scaled to the small size of typical farms and that are designed to improve labor efficiency but not to replace it. Where modern agricultural technologies--artificial fertilizers and pesticides, complex sophisticated machinery, large and expensive irrigation projects--have been applied in countries with "undeveloped" agricultures, the results often have been unsatisfactory. Large dams may prove to have negative environmental impacts. Heavy machinery breaks down, needs expensive fuel, and affects fragile soils. New seeds prove to be unsuited to the climate, soil, or growing conditions of the new countries where they are planted. Trying to impose advanced techniques in areas that practice traditional agriculture may often do more harm than good. Recent attempts to improve traditional technologies seek to provide small-scale devices that are inexpensive, easy to produce, and meet the needs of a specific region. Stoves, for example, may not seem vital to a village's well-being, but traditional ways of cooking, such as using open fires, are inefficient, consume firewood out of proportion to the cooking heat they provide, and are the principal cause of deforestation in many undeveloped regions. Clay, stone, or scrap-iron stoves have been designed that are inexpensive to make and use less than half the fuel of open fires. Solar stoves capture the Sun's heat to provide fire for cooking. Solar vegetable dryers can preserve a season's crop of fruits and vegetables. Improvements on the traditional granary storage baskets, the use of cement rather than tin to store water--these and many other devices could lighten the burden of work in villages and preserve resources as well. Improving the productivity of farm animals is another neglected area. Using specially designed scoops, a team of oxen can dig out a pond to catch and hold underground rain water. Although most animal-pulled plows require two draft animals, a special plow has been designed for farmers who own only one animal. Other areas of small but important technological advance include improving animal nutrition and soil fertility by growing nitrogenous food and fodder, such as cowpeas; using small gasoline-powered plows and other machinery that can be managed and operated by one person; increasing the use of terraces in hilly regions to lower soil erosion; and building raised seedbeds to increase evaporation from waterlogged soils. Genetic Technology \Tplant breeding\t is modification of a plant's genetic makeup in a purposeful way. The general goal of plant breeding is to assemble into single varieties the best possible combination of genes that control desirable traits. The traits of importance include yield, local environmental adaptation, uniformity, quality, disease or insect resistance, and early maturity. Numerous plant-breeding methodologies can be used worldwide, but actual testing of experimental varieties must be done in the regions in which they are planned for use in order to ensure suitability. Because the raw material for plant breeding is genetic diversity, \Lgene bank\ls--which have collections of seeds of wild relatives and unimproved and improved varieties of crops--have been organized to preserve the genetic resources of major food crops for future use by plant breeders. Efforts of agricultural research in the 1960s to find ways for farmers in developing countries to produce far more food on the same amount of land led to early successes popularly called the \Tgreen revolution\t, initiated by a plant scientist, Dr. Norman \TBorlaug\t. Research centers, in Asia, Africa, and Latin America, conduct applied research on subsistence food crops and livestock problems of regional importance. The best-known centers are the International Rice Research Institute in the Philippines--which developed hardy, short-stemmed rice--and the International Center for the Improvement of Corn and Wheat in Mexico, which developed high-protein corn and wheat adaptable to subtropical regions. Nearly 50% of the world's wheat land was sown in the new wheats, and more than a quarter of all rice land was sown in the new rice by the mid-1970s. Enthusiasm for the early success of the international research centers has been tempered by a growing realization that agricultural change is much more complex than had originally been anticipated, and that high production levels with the new seeds require a costly package that includes, for instance, chemical fertilizers and pesticides that are often unavailable to small farmers. There are, however, many opportunities for countries to develop native plants into important food crops. Ethiopia, plagued by drought and famine in the 1980s, provides a case in point. The Ethiopians grow a grain called t'ef, which, it is believed, has barely developed from its original wild form. Unlike other staple grains, t'ef needs little rain and grows well in high, cold regions. Its straw makes excellent fodder, and its tiny grains are highly nutritious for humans. Breeding the right varieties of t'ef--that is, working with those seeds which presently grow on marginal land under arid, cold conditions--could result in a grain that might provide basic food needs for Ethiopia as well as for other mountainous African countries. Ethiopia is one of the rare places in the world where many plant species that now grow in a host of different varieties around the world can still be found in their primitive, uncultivated forms. Some of them offer great potential: there are many hundreds of wild pea varieties, for example. Oil plants such as castor bean have yet to receive attention from researchers; coffee, show wild ancestors still flourish in Ethiopia, might become an important export crop for the country, which at present has none. These, and many other plants that offer great genetic diversity, are collected and sent to gene banks, but their existence on their native soil is threatened by the introduction of new, high-yielding foreign plants developed by plant breeders outside Ethiopia. Agricultural Education New information and technology that can help farmers increase their production must be communicated effectively if it is to achieve its purpose (see \Tagricultural education\t). Physical constraints, such as a poor road system or underdeveloped mass communications system, can handicap the spread of information, but various cultural constraints--including verbal or scientific illiteracy among farmers or the communication gap between farmers and agricultural researchers and technicians created by such differences as economic class and cultural assumptions--may present an even greater challenge. Effective communications with small farmers varies in approach according to circumstances. In parts of Africa, for example, radios and puppet shows have been used to spread agricultural information quickly and effectively. In the Philippines, specially trained agricultural agents provide assistance to farmers and spread information by demonstrating it in the farmers' fields. In China, agricultural communes often have one of their members responsible for spreading information about improved practices to the commune workers. In each instance, the approach, although carried out by some institution, operates outside the formal educational channels. India has developed a highly successful national agricultural management program called the Training and Visit System. Village Extension Workers (VEWs) work in the fields as part of their training--unlike workers in other countries, who may be graduates of agricultural schools but know little about practical cultivation methods. VEWs make the same circuit of visits every two weeks appearing regularly to teach new technologies and methods to farmers, and to listen to their problems. They carry legitimate complaints back to research agriculturists, who attempt to find appropriate answers. VEWs also work with village women, setting up nutrition programs and helping to create small cottage industries that will bring added cash into the village. The techniques employed in India are now being tried in some 40 different countries, with emphasis on Africa where small farms abound. Cultivation of New Crops The discovery of the New World resulted in an increase of available foods both in Europe and in the colonized territories. Such new crops as potatoes, tomatoes, corn, and green peppers became staples in countries throughout the world--although in some cases, many years passed between the introduction of a new food and its acceptance into the national diet. The world today is still rich in foods that might well be adapted to cultivation in many countries, although they now grow only in a single area. Interest presently is focused on South America, where many indigenous crops were no longer cultivated after the Spanish conquest, and where others still grow, but in regions so remote that few know about them. Among these are a wide range of potato varieties, each with different growth and keeping habits. Quinoa, a nutritious Andean grain is now being grown in small quantities in the United States. Tarwi, an Andean legume, has nitrogen-fixing properties and thus enriches soil, while its seed equals soybean in protein and oil content. \Tamaranth\t, a protein-rich seed, flourishes throughout the warmer areas of Latin America. Kiwicha, another grain, can be processed like corn or wheat. Oca, a bright yellow tuber that produces prolific crops, is already eaten in new Zealand, where it serves as a potato substitute. Not every vegetable grown in Latin America may be suitable for cultivation in other parts of the world, but the existence of so many unknown, untried foods represents a rich source for experiment and, with some possible modifications, for enlarging food outputs wherever they may be capable of being cultivated. WORLD ORGANIZATIONS AND AGRICULTURAL AID Agricultural assistance and adequate food supply have been issues of primary interest to the \TFood and Agriculture Organization\t, primarily a fact gathering, research, and technological-aid group; to the \TWorld Bank\t, 30 percent of whose loans have been for agricultural development over the years since 1944, when it was established; and to the United Nations Development Program, much of whose technical assistance is devoted to developing irrigation systems, controlling erosion, and creating effective storage, transportation, and marketing systems for foods. The \TUnited Nations Children's Fund\t has among its many programs one in which village women of developing nations are helped to produce and process food. Until recently, relatively little consideration was given by governments to the politics or sociology of agriculture and economic development--how to redistribute national income or to increase the income of the poor so that they can participate fully in the market for food, or how to give small farmers more incentives to produce for the market through land ownership, credit on reasonable terms, or farming necessities at fair prices. A growing international consensus, however, is that food should be economically available to people having low income and that small farmers of developing nations need aid to produce more food in ways that fit their circumstances. The underlying problem, according to this consensus, is not a lack of food supply, but rather the lack of enough political will to resolve food problems with the knowledge and resources that are available. \Tpatricia\t KUTZNER AND \TDavid\t SAMMONS Bibliography: Andrae, G., and Beckman, B., The Wheat Trap: Bread and Underdevelopment in Nigeria (1986); Berardi, G. M., World Food Population and Development (1986); Chazen, N., and Shaw, T. M., Coping with Africa's Food Crisis (1988); Cox, G. W., and Atkins, M. D., Agricultural Ecology (1979); Croxell, H. E., and Smith, L. P., The Fight for Food: Factors Limiting Agricultural Production (1984); Glantz, M. H., ed., Drought and Hunger in Africa: Denying Famine a Future (1987); Hall, Alan, et al., "The Second Green Revolution," Business Week, Aug. 25, 1980; Harwood, R., Small Farm Development (1979); Kent, G., The Political Economy of Hunger (1984); Kutzner, Patricia L., Who's Involved with Hunger, rev. ed (1976); Lappe, Frances Moore, and Collins, Joseph, Food First (1979) and World Hunger: Ten Myths, rev. ed. (1979); Pimentel, David and Marcia, Food, Energy, and Society (1979); Plucknett, D., et al., Gene Banks and the World's Food (1987); Presidential Commission on World Hunger, Overcoming World Hunger: The Challenge Ahead (1980); Seavoy, R., Famine in Peasant Societies (1986); World Bank, Poverty and Hunger: Issues and Options for Food Security in Developing Countries (1986).