关于farming的内容

关于farming的内容
用英语

主要是农业方面的简介,分了若干个目录
Introduction
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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.
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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.
II
World Agriculture
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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.
III
History
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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.
A
Prehistoric Agriculture
Early farmers were, archaeologists agree, largely of Neolithic culture. Sites occupied by such people are located in southwestern Asia in what are now Iran, Iraq, Israel, Jordan, Syria, and Turkey ; in southeastern Asia, in what is now Thailand; in Africa, along the Nile River in Egypt; and in Europe, along the Danube River and in Macedonia, Thrace, and Thessaly (historic regions of southeastern Europe). Early centers of agriculture have also been identified in the Huang He (Yellow River) area of China; the Indus River valley of India and Pakistan; and the Tehuacán Valley of Mexico, northwest of the Isthmus of Tehuantepec. See also Stone Age.
The dates of domesticated plants and animals vary with the regions, but most predate the 6th millennium bc, and the earliest may date from 10,000 bc. Scientists have carried out carbon-14 testing of animal and plant remains and have dated finds of domesticated sheep at 9000 bc in northern Iraq; cattle in the 6th millennium bc in northeastern Iran; goats at 8000 bc in central Iran; pigs at 8000 bc in Thailand and 7000 bc in Thessaly; onagers, or asses, at 7000 bc in Iraq; and horses around 4000 bc in central Asia. The llama and alpaca were domesticated in the Andean regions of South America by the middle of the 3rd millennium bc.
According to carbon dating, wheat and barley were domesticated in the Middle East in the 8th millennium bc; millet and rice in China and Southeast Asia by 5500 bc; and squash in Mexico about 8000 bc. Legumes found in Thessaly and Macedonia are dated as early as 6000 bc. Flax was grown and apparently woven into textiles early in the Neolithic Period.
The transition from hunting and food gathering to dependence on food production was gradual, and in a few isolated parts of the world this transition has not yet been accomplished. Crops and domestic meat supplies were augmented by fish and wildfowl as well as by the meat of wild animals. The farmer began, most probably, by noting which of the wild plants were edible or otherwise useful and learned to save the seed and to replant it in cleared land. Lengthy cultivation of the most prolific and hardiest plants yielded stable strains. Herds of goats and sheep were assembled from captured young wild animals, and those with the most useful traits—such as small horns and high milk production—were bred. The wild aurochs was the ancestor of European cattle, and an Asian wild ox of the zebu, was the ancestor of the humped cattle of Asia. Cats, dogs, and chickens were also domesticated very early.
Neolithic farmers lived in simple dwellings—caves and small houses of sunbaked mud brick or reed and wood. These homes were grouped into small villages or existed as single farmsteads surrounded by fields, sheltering animals and humans in adjacent or joined buildings. In the Neolithic Period, the growth of cities such as Jericho (founded about 9000 bc) was stimulated by the production of surplus crops.
Pastoralism (individual country living) may have been a later development. Evidence indicates that mixed farming, combining cultivation of crops and stock raising, was the most common Neolithic pattern. Nomadic herders, however, roamed the steppes of Europe and Asia, where the horse and camel were domesticated.
The earliest tools of the farmer were made of wood and stone. They included the stone adz, an axlike tool with blades at right angles to the handle, used for woodworking; the sickle or reaping knife with sharpened stone blades, used to gather grain; the digging stick, used to plant seeds and, with later adaptations, as a spade or hoe; and a rudimentary plow, a modified tree branch used to scratch the surface of the soil and prepare it for planting. The plow was later adapted for pulling by oxen.
The hilly areas of southwestern Asia and the forests of Europe had enough rain to sustain agriculture, but Egypt depended on the annual floods of the Nile River to replenish soil moisture and fertility. The inhabitants of the Fertile Crescent around the Tigris and Euphrates rivers in the Middle East also depended on annual floods to supply irrigation water. Drainage was necessary to prevent the erosion of land from the hillsides through which the rivers flowed. The farmers who lived in the area near the Huang He developed a system of irrigation and drainage to control the damage caused to their fields in the flood plain of the meandering river.
Although Neolithic settlements were more permanent than the camps of hunting peoples, villages had to be moved periodically in some areas when the fields lost their fertility from continuous cropping. This was most necessary in northern Europe, where fields were produced by the slash-and-burn method of clearing. Settlements along the Nile River, however, were more permanent, because the river deposited fertile silt annually.
B
Historical Agriculture Through the Roman Period
With the close of the Neolithic period and the introduction of metals, the age of innovation in agriculture was largely over. The historical period—known through written and pictured materials, including the Bible; Middle Eastern records and monuments; and Chinese, Greek, and Roman writings—was highlighted by agricultural improvements. A few high points must serve to outline the development of worldwide agriculture in this era, roughly defined as 2500 bc to ad 500. For a similar period of development in Central and South America, somewhat later in date (see Native Americans of North America: Agriculture).
Some plants became newly prominent. Grapes and wine were mentioned in Egyptian records about 2900 bc, and trade in olive oil and wine was widespread in the Mediterranean area by the 1st millennium bc. Rye and oats were cultivated in northern Europe about 1000 bc.
Many vegetables and fruits, including onions, melons, and cucumbers, were grown by the 3rd millennium bc in Ur (now Iraq). Dates and figs were an important source of sugar in the Middle East, and apples, pomegranates, peaches, and mulberries were grown in the Mediterranean area. Cotton was grown and spun in India about 2000 bc, and linen and silk were used extensively in 2nd-millennium bc China. Felt was made from the wool of sheep in Central Asia and the Russian steppes.
The horse, introduced to Egypt about 1600 bc, was already domesticated in Mesopotamia and Asia Minor. The ox-drawn four-wheeled cart for farm work and two-wheeled chariots drawn by horses were familiar in northern India in the 2nd millennium bc.
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Improvements in tools and implements were particularly important. Tools of bronze and iron were longer lasting and more efficient, and cultivation was greatly improved by such aids as the ox-drawn plow fitted with an iron-tipped point, noted in the 10th century bc in Palestine. In Mesopotamia in the 3rd millennium bc a funnel-like device was attached to the plow to aid in seeding, and other early forms of seed drills were used in China. Farmers in China further improved efficiency with the invention of a cast-iron moldbar plow. Threshing was also done with animal power in Palestine and Mesopotamia, although reaping, binding, and winnowing were still done by hand. Egypt retained hand seeding through this period on individual farm plots and large estates alike.
Storage methods for oil and grain were improved. Granaries—jars, dry cisterns, silos, and bins containing stored grain—provided food for city populations. Without adequate food supplies and trade in both food and nonfood items, the high civilizations of Mesopotamia, northern India, Egypt, Greece, and Rome would not have been possible.
Irrigation systems in China, Egypt, and the Middle East were refined and expanded, putting more land into cultivation. The forced labor of peasants and the growth of bureaucracies to plan and supervise work on irrigation systems were probably basic in the development of the city-states of Sumer (now Iraq and Kuwait). Windmills and water mills, developed toward the end of the Roman period, increased control over the many uncertainties of weather. The introduction of fertilizer, mostly animal manures, and the rotation of fallow and crop land increased crop production.
Mixed farming and stock raising, which were flourishing in the British Isles and on the continent of Europe as far north as Scandinavia at the beginning of the historical period, already displayed a pattern that persisted throughout the next 3,000 years. In many regions, fishing and hunting supplemented the food grown by farmers.
About ad 100 Roman historian Cornelius Tacitus described the Germans as a tribal society of free peasant warriors who cultivated their own lands or left them to fight. About 500 years later, a characteristic European village had a cluster of houses in the middle, surrounded by rudely cultivated fields comprising individually owned farmlands; and meadows, woods, and wasteland were used by the entire community. Oxen and plow were passed from one field to another, and harvesting was a cooperative effort.
The Roman Empire appears to have started as a rural agricultural society of independent farmers. In the 1st millennium bc, after the city of Rome was established, however, agriculture started a development that reached a peak in the Christian era. Large estates that supplied grain to the cities of the empire were owned by absentee landowners and cultivated by slave labor under the supervision of hired overseers. As slaves, usually war captives, decreased in number, tenants replaced them. The late Roman villa of the Christian era approached the medieval manor in organization; slaves and dependent tenants were forced to work on a fixed schedule, and tenants paid a predetermined share to the estate owner. By the 4th century ad, serfdom was well established, and the former tenant was attached to the land.