Agriculture, art, science, and industry of managing the growth of plants and animals for human use. In a broad sense agriculture includes cultivation of the soil, growing and harvesting crops, breeding and raising livestock, dairying, and forestry (see Animal Husbandry; Crop Farming; Dairy Farming; Forestry; Poultry Farming; Soil Management). Regional and national agriculture are covered in more detail in individual continent, country, state, and Canadian province articles. Modern agriculture depends heavily on engineering and technology and on the biological and physical sciences. Irrigation, drainage, conservation, and sanitary engineering—each of which is important in successful farming—are some of the fields requiring the specialized knowledge of agricultural engineers. Agricultural chemistry deals with other vital farming concerns, such as the application of fertilizer, insecticides (see Pest Control), and fungicides, soil makeup, analysis of agricultural products, and nutritional needs of farm animals. Plant breeding and genetics contribute immeasurably to farm productivity.
Genetics has also made a science of livestock breeding. Hydroponics, a method of soilless gardening in which plants are grown in chemical nutrient solutions, may help meet the need for greater food production as the world’s population increases. The packing, processing, and marketing of agricultural products are closely related activities also influenced by science. Methods of quick-freezing and dehydration have increased the markets for farm products (see Food Processing and Preservation; Meat Packing Industry). Mechanization, the outstanding characteristic of late 19th- and 20th-century agriculture, has eased much of the backbreaking toil of the farmer.
More significantly, mechanization has enormously increased farm efficiency and productivity (see Agricultural Machinery). Animals including horses, oxen, llamas, alpacas, and dogs, however, are still used to cultivate fields, harvest crops, and transport farm products to markets in many parts of the world. Airplanes and helicopters are employed in agriculture for seeding, spraying operations for insect and disease control, transporting perishable products, and fighting forest fires. Increasingly satellites are being used to monitor crop yields. Radio and television disseminate vital weather reports and other information such as market reports that concern farmers. Computers have become an essential tool for farm management. |
Over the 10, 000 years since agriculture began to be developed, peoples everywhere have discovered the food value of wild plants and animals, and domesticated and bred them. The most important crops are cereals such as wheat, rice, barley, corn, and rye; sugarcane and sugar beets; meat animals such as sheep, cattle, goats, and pigs or swine; poultry such as chickens, ducks, and turkeys; animal products such as milk, cheese, and eggs; and nuts and oils. Fruits, vegetables, and olives are also major foods for people. Feed grains for animals include soybeans, field corn, and sorghum. See also Grasses; Hay; Grain; Legume; Silage. Agricultural income is also derived from nonfood crops such as rubber, fiber plants, tobacco, and oil seeds used in synthetic chemical compounds, as well as animals raised for pelts. Conditions that determine what is raised in an area include climate, water supply and waterworks, terrain, and ecology.
In 2003, 44 percent of the world’s labor force was employed in agriculture. The distribution ranged from 66 percent of the economically active population in sub-Saharan Africa to less than 3 percent in the United States and Canada. In Asia and the Pacific the figure was 60 percent; in Latin America and the Caribbean, 19 percent; and in Europe, 9 percent. Farm size varies widely from region to region. In the early 2000s the average for Canadian farms was about 273 hectares (about 675 acres) per farm; for farms in the United States, 180 hectares (440 acres). By contrast, the average size of a single land holding in India was 2 hectares (about 5 acres). Size also depends on the purpose of the farm. Commercial farming, or production for cash, usually takes place on large holdings. The latifundia of Latin America are large, privately owned estates worked by tenant labor. Single crop plantations produce tea, rubber, and cocoa. Wheat farms are most efficient when they comprise thousands of hectares and can be worked by teams of people and machines.
Australian sheep stations and other livestock farms must be large to provide grazing for thousands of animals. Individual subsistence farms or small-family mixed-farm operations are decreasing in number in developed countries but are still numerous in the developing countries of Africa and Asia. Nomadic herders range over large areas in sub-Saharan Africa, Afghanistan, and Lapland; and herding is a major part of agriculture in such areas as Mongolia. Much of the foreign exchange earned by a country may be derived from a single agricultural commodity; for example, Sri Lanka depends on tea, Denmark specializes in dairy products, Australia in wool, and New Zealand and Argentina in meat products. In the United States, wheat, corn, and soybeans have become major foreign exchange commodities in recent decades. The importance of an individual country as an exporter of agricultural products depends on many variables.
Among them is the possibility that the country is too little developed industrially to produce manufactured goods in sufficient quantity or technical sophistication. Such agricultural exporters include Ghana, with cocoa, and Myanmar (formerly Burma), with rice. However, a developed country may produce surpluses that are not needed by its own population; this is the case with the United States, Canada, and some other countries. Because nations depend on agriculture not only for food but for national income and raw materials for industry as well, trade in agriculture is a constant international concern. It is regulated by the World Trade Organization. The Food and Agriculture Organization of the United Nations (FAO) directs much attention to agricultural trade and policies. According to the FAO, world agricultural production, stimulated by improving technology, grew steadily from the 1960s to the 1990s.
Per capita food production saw sustained growth in Latin America, the Caribbean, Asia, and the Pacific, and limited growth in the Near East and North Africa. The only region not to experience growth during the 1980s and 1990s was sub-Saharan Africa, which suffered from climatic conditions that made agriculture difficult. Although agricultural growth began to taper off in the year 2000, it continued to outpace world population growth. See also Food. The history of agriculture may be divided into five broad periods of unequal length, differing widely in date according to region: prehistoric, historic through the Roman period, feudal, scientific, and industrial. A countertrend to industrial agriculture, known as sustainable agriculture or organic farming, may represent yet another period in agricultural history.
Organic Farming, system of agriculture that excludes the use of synthetic pesticides, growth hormones, antibiotics, genetically modified seeds and animal breeds, and irradiation. Organic farmers instead rely on ecosystem management, including the use of pesticides and fertilizers derived from plants, animal wastes, and minerals. They incorporate biological methods, such as the use of one organism to suppress another, to help control pests. The methods used in organic farming seek to increase soil fertility, balance insect populations, and reduce air, soil, and water pollution. In the United States, organic farming is a rapidly growing sector of agriculture. In 2006 organic food sales reached $16. 7 billion, up from $7 billion in 2001. Exports of organic food products are also growing, particularly to Japan and Europe. Organic farming combines a variety of methods to maintain the health of soil, prevent soil erosion, and control pests with minimal or no use of synthetic pesticides. Conventional farmers also use some of these methods, but to a lesser degree.
Fertilizers are used to provide the minerals lacking in some soils, and to replace the minerals removed from the soil by crops as they grow. Many conventional farmers rely on concentrated chemical fertilizers that are rapidly absorbed by plants. These fertilizers produce quick growth but may kill important soil organisms, such as earthworms and beneficial bacteria. Organic farmers use manure, compost (a mixture of decaying organic matter that is rich in beneficial soil microorganisms), and other natural materials to nourish soil organisms, which in turn make minerals available to plants. Organic farmers are more likely than conventional farmers to rotate crops, a technique that replenishes soil nutrients without the use of synthetic fertilizers. In crop rotation, a field is used for one to several years to grow one type of crop, such as corn or wheat, followed by a season in which a legume such as alfalfa or soybean is planted.
Legume roots harbor beneficial bacteria that incorporate nitrogen from the air into the soil (see Nitrogen Fixation), enriching the soil and reducing the need for nitrogen-containing fertilizers. Crop rotation also conserves nutrients. For example, the roots of the first crop may be near the surface and the second crop’s roots may be deeper, so that nutrients are drawn from different depths in the soil. Soil held in place by plant roots is less likely to blow or wash away, or erode, than bare soil. Organic farmers minimize soil erosion with cover crops—short-lived plants, often grasses or legumes—that protect the soil between the harvesting of one crop and the planting of the next. Many organic farmers also conserve soil by practicing no-till or low-till farming, avoiding the use of plows to turn the soil, or using implements that only slice or slightly turn the soil. They may also leave the unharvested portion of a crop in the field to cover the soil, preventing soil erosion from wind or rain.
Conventional farms rely on an array of synthetic pesticides to kill weeds, disease-causing fungi, and harmful insects. These pesticides are manufactured by chemically processing petroleum, natural gas, ammonia, and a number of other raw materials. They include active and inactive ingredients, both of which can be highly toxic and long lasting. Organic farmers typically use pesticides primarily derived from chemically unaltered plant, animal, or mineral substances in which the active toxic ingredient breaks down rapidly to become nontoxic after being applied to the crop. Pyrethrum (a substance extracted from the chrysanthemum), a variety of soaps, and oil from the neem tree are among the insecticides used by organic farmers. Bordeaux mix, a combination of calcium carbonate and copper, is used by organic farmers to control disease-causing fungi. In addition to using natural pesticides, organic farmers control pests by planting different crops in wide, alternating bands, a technique called intercropping. This approach interrupts the movement of disease-causing organisms through a field, since many insects and fungi feed on just one type of crop.
Organic farmers also reduce insect damage by spraying crops with bacteria that kill larvae (immature insects) and planting crops that attract ladybugs, lacewings, and other beneficial insects that prey on unwanted insects. Organic farmers use many methods for weed control. Mulching involves covering the soil around crops with straw or other materials that smother weeds. Cover crops can be planted in the fall and turned under in a few months; they help control weeds by competing with them—an oat crop, for example, grows faster than weeds and deprives them of the nutrients they need to produce seeds. Other types of cover crops, such as cereal rye, release substances from their roots that inhibit weed seed germination. Organic farmers sometimes use a variety of tractor-drawn equipment to uproot weeds that emerge with crops. Organic farming is sometimes referred to as sustainable agriculture, although the two concepts have subtle but significant differences.
Sustainable agriculture seeks to improve the entire food and agricultural system by balancing production and consumption. For example, a farmer practicing sustainable agriculture may use the manure from the animals to fertilize the fields of grain that are grown to feed the animals. Eliminating the purchase of fertilizer reduces the cost of growing grain, and growing grain for animal feed rather than buying it reduces the cost of raising livestock. Sustainable agriculture also addresses the environmental, economic, and social issues related to agricultural systems. It attempts to ensure that arable land is protected so that current and future generations will be able to farm it successfully; many involved in sustainable agriculture also seek to preserve the vitality of family-owned farms and rural communities. A sustainable farm may not be organic, and an organic farm may not be sustainable, although they may use similar techniques.
For consumers, the most obvious benefit of organic farming is health-related. Studies show that organically grown food contains higher levels of essential minerals than conventionally grown food. In addition, organic food is free from genetically modified organisms (GMOs), hormones, and antibiotics, and has little or no pesticide residue. Longer-term benefits of organic farming include the preservation and enhancement of soil, increasing the likelihood that it will continue to produce quality food for future generations. Organic farming encourages healthy populations of beneficial insects that keep destructive insects under control. It also helps preserve aquatic life and clean water by minimizing the flow of toxic pesticides into streams, rivers, and lakes. Critics of organic farming argue that the method is less profitable, requiring more labor and management skill than a conventional farm. Savings on pesticides, fertilizers, and fuels, however, usually offset the cost of the extra labor. And the environmental benefits of organic farming represent long-term savings, not just for the organic farmer, but also for future generations. In 1990 the Congress of the United States passed the Organic Foods Production Act. The act mandates the United States Department of Agriculture (USDA) to establish national standards governing the methods used to grow, process, and market organic agricultural products.
In 2000 the USDA established new regulations governing the production of organic food and in 2002 the National Organic Program was established. These regulations establish certification standards and prohibit the use of genetically modified ingredients, irradiation to decontaminate products, and sewage sludge as fertilizers for any food sold as an organic product. Products labeled “ 100 percent organic” must contain only organic ingredients, while those labeled “ organic” must contain at least 95 percent organic ingredients. Processed food containing at least 70 percent organic ingredients can be labeled “ Made with organic ingredients,” and as many as three of the organic ingredients can be listed on the product’s packaging. Only products made from at least 95 percent organic ingredients can carry the USDA organic seal on their packaging and in advertisements. Prior to the invention of synthetic fertilizers and pesticides, all farming was “ organic” by definition.
In the modern age, one of the first proponents of organic farming was the British agriculturalist Sir Albert Howard, who, in his 1940 book An Agricultural Testament, advocated farming without synthetic fertilizers and pesticides. British agriculturist Lady Eve Balfour was also involved in the 20th-century organic farming movement. Her 30-year research farm, the Haughley Experiment, was the site of numerous experiments comparing organic and conventional farming. Balfour’s book, The Living Soil (1943), corroborated Howard’s studies and documented the importance of healthy soil for farming.
The work of Howard and Balfour inspired American researcher and publisher J. I. Rodale to found Organic Farming and Gardening magazine in 1942 (now called Organic Gardening), which educates the public about organic techniques. Rodale also established the nonprofit Soil and Health Foundation research center (now called the Rodale Institute). Rachel Carson, a marine biologist with the United States Fish and Wildlife Service, added momentum to the organic farming movement with her book Silent Spring (1962), which chronicles the harmful effects of pesticides on wildlife. Also in the United States, Helen and Scott Nearing pioneered in organic farming. Their book Living the Good Life (1954) and their numerous other publications promoted organic farming and helped inspire the back-to-the-land movement of the 1960s and 1970s.