Agriculture is the practice of cultivating plants and herding animals for food, fiber, and other products. Agriculture is the single largest land use in the world and it is the single greatest employer. Nearly 38 percent of the earth’s land area is in agriculture. In 2004, more than 2.6 billion people, or 42 percent of the world’s population, were engaged in agriculture. 10,000 years ago, only a trivial fraction of the earth’s surface was dedicated to agriculture. Since then, agriculture has replaced prairies, wetlands, forests, and other ecosystems, allowing the global population to exceed 6.3 billion. Agriculture features prominently in many debates linking environment and society. It is blamed for reducing biodiversity, polluting aquatic ecosystems with eroded soils and toxic chemicals, and contributing to global climate change.
Surface layer of the earth, composed of fine rock material disintegrated by geological processes; and humus, the organic remains of decomposed vegetation. In agriculture, soil is the medium that supports crop plants, both physically and biologically. Soil may be from a few inches to several feet thick.
Natural process caused the action of wind, water, and ice on the surface of the Earth, which wears away and redistributes the soil layer. If the rate of erosion exceeds the rate of soil formation (from rock and decomposing organic matter), the land will become infertile. If unchecked, soil erosion results in the formation of deserts (desertification). Soil erosion can also be caused or accelerated by human activities, primarily with regard to poor or unwise agricultural methods.
Throughout the world, especially in the Northern Hemisphere, milk, cheese, butter, ice cream, and other dairy products, have been central elements of food production. Over the centuries improvements in cattle breeding and nutrition, as well as new dairy techniques, led to the increased production of dairy goods. Hand-operated churns and separators were used to make butter and cream, and those close to a barnyard had access to fresh milk. By the late nineteenth century, new science and technology had begun to transform dairy production, particularly in the U.S. and Europe.
Substance containing some or all of a range of about 20 chemical elements necessary for healthy plant growth, used to compensate for the deficiencies of poor or depleted soil . Fertilizers may be organic, for example farmyard manure, composts, bonemeal, blood, and fishmeal; or inorganic (synthetic or artificial), in the form of simple compounds, mainly of nitrogen, phosphate, and potash, which have been used on a very much increased scale since 1945. Compounds of nitrogen and phosphorus are of particular importance. Elements in the soil are taken up through the roots of plants in solution, becoming part of the compounds forming the plant. If plants are allowed to die and decompose, these compounds return to the soil as part of a natural cycle, such as the nitrogen cycle.
any large, ruminant, even-toed, hoofed mammal of the genus Bos , family Bovidae, including wild species such as the yak, gaur, gayal, banteng, and kouprey, as well as domestic breeds. Asiatic water buffaloes Bubalus , African buffaloes Syncerus , and American bison Bison are not considered true cattle. Cattle are bred for meat (beef cattle) or milk (dairy cattle). Cattle were first domesticated in the Middle East during the Neolithic period, about 8000 BC . They were brought north into Europe by migrating Neolithic farmers. Fermentation in the four-chambered stomach allows cattle to make good use of the grass that is normally the main part of the diet.
Farming without the use of synthetic fertilizers (such as nitrates and phosphates) or pesticides (herbicides, insecticides, and fungicides) or other agrochemicals (such as hormones, growth stimulants, or fruit regulators). The use of any form of genetically modified crops, animals, or ingredients is also banned. Organic farming uses techniques commonly used in agriculture before the development of synthetic chemicals, drugs, and genetic modification, including frequent crop rotations with periods of fallow; natural fertilizers; free-range farm animals; smaller herd sizes; encouraging beneficial insect population growth; and increasing the diversity of crop species. In place of artificial fertilizers, compost, manure, seaweed, or other substances derived from living things are used (hence the name ‘organic’).
or white potato, common name for a perennial plant ( Solanum tuberosum ) of the family Solanaceae ( nightshade family) and for its swollen underground stem, a tuber, which is one of the most widely used vegetables in Western temperate climates. Evidence of the domesticated potato, which is native to South America, has been found at a 12,500 year-old archaeological site in Chile. The potato was cultivated by the Incas in the Andes, and in pre-Columbian times its culture spread widely among Native Americans, for whom it was a staple food. Its history is difficult to trace, partly because the name potato was also used by early writers for the sweet potato ( Ipomoea batatas ) and for other unrelated plants.