Agriculture (encompasses farming, ranching, and the tending of orchards and vineyards) is the production of food, feed, fiber, fuel and other goods by the systematic raising of plants and animals.

Agri is from Latin ager, meaning "a field", and culture is from Latin cultura, meaning "cultivation" in the strict sense of tillage of the soil. A literal reading of the English word yields: tillage of the soil of a field. In modern usage, the word agriculture covers all activities essential to food/feed/fiber production, including all techniques for raising and "processing" livestock. Agriculture is also short for the study of the practice of agriculture—more formally known as agricultural science.

The history of agriculture is a major element of human history, as agricultural progress has been a crucial factor in worldwide socio-economic change, including wealth-building and militaristic specializations rarely seen in hunter-gatherer cultures—when farmers became capable of producing food beyond the needs of their own families, others in the tribe/nation/empire were freed to devote themselves to ambitions and enterprises other than food acquisition.

42% of the world's laborers are employed in agriculture, making it by far the most common occupation. However, agricultural production accounts for less than 5% of the Gross World Product (an aggregate of all Gross Domestic Products).[1]

Overview
The term "farming" covers the wide spectrum of agricultural practices. On one end of the spectrum is the subsistence farmer, who farms a small area with limited resource inputs, and produces only enough food to meet the needs of his/her family. At the other end is commercial intensive agriculture, including industrial agriculture. Such farming involves large fields and/or numbers of animals, large resource inputs (pesticides, fertilizers, etc.), and a high level of mechanization. These operations generally attempt to maximize financial income from grain, produce, or livestock.

Modern agriculture extends well beyond the traditional production of food for humans and animal feeds. Other agricultural production goods include timber, fertilizers, animal hides, leather, industrial chemicals (starch, sugar, ethanol, alcohols and plastics), fibers (cotton, wool, hemp, and flax), fuels (methane from biomass, biodiesel), cut flowers, ornamental and nursery plants, tropical fish and birds for the pet trade, and both legal and illegal drugs (biopharmaceuticals, tobacco, marijuana, opium, cocaine).

The twentieth century saw massive changes in agricultural practice, particularly in agricultural chemistry and in mechanization. Agricultural chemistry includes the application of chemical fertilizer, chemical insecticides (see pest control), and chemical fungicides, soil makeup, analysis of agricultural products, and nutritional needs of farm animals. Up to and including the 1970s, surface runoff of fertilizer and pesticides was a growing and uncontrolled problem. Staring roughly in 1980, many Western nations, prodded by dozens of environmental action groups, began to implement effective controls on agriculture-related pollution, and the green revolution spread many of the benefits of agricultural chemistry to farms throughout the world, without the extreme pollution that originally accompanied them. Mechanization has also enormously increased farm efficiency and productivity in most regions of the world, especially in the form of the tractor and various gins (short for "engine") like the cotton gin, semi-automatic balers and threshers (see agricultural machinery).

Other recent changes in agriculture include hydroponics, plant breeding, hybridization, gene manipulation, better management of soil nutrients, and improved weed control. Genetic engineering has yielded crops which have capabilities beyond those of naturally occurring plants, such as higher yields and disease resistance. Modified seeds germinate faster, and thus can be grown in an extended growing area. Genetic engineering of plants has proven controversial, particularly in the case of herbicide-resistant plants.

Engineers may develop plants for irrigation, drainage, conservation and sanitary engineering, particularly important in normally arid areas which rely upon constant irrigation, and on large scale farms.

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 preservation and meat packing industry).

Animals, including horses, mules, oxen, camels, llamas, alpacas, and dogs, are often used to cultivate fields, harvest crops and transport farm products to markets. Animal husbandry not only refers to the breeding and raising animals for meat or to harvest animal products (like milk, eggs, or wool) on a continual basis, but the breeding and care of species for work and companionship.

Airplanes, helicopters, trucks, tractors, and combines are used in Western agriculture for seeding, spraying operations for insect and disease control, harvesting, aerial topdressing and transporting perishable products. 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.


Ploughing rice paddies with water buffalo, in Indonesia.According to the National Academy of Engineering in the United States, agricultural mechanization is one of the 20 greatest engineering achievements of the 20th century. Early in the century, it took one American farmer to produce food for 2.5 people. Today, due to advances in agricultural technology, a single farmer can feed over 130 people.[2] This comes at a cost, however. A large energy input, often from fossil fuel, are required to maintain such high levels of output.

In recent years, some aspects of intensive industrial agriculture have been the subject of increasing discussion. The widening sphere of influence held by large seed and chemical companies, meat packers and food processors has been a source of concern both within the farming community and for the general public. Another issue is the type of feed given to some animals that can cause bovine spongiform encephalopathy in cattle. There has also been concern because of the disastrous effect that intensive agriculture has on the environment. In the US, for example, fertilizer has been running off into the Mississippi for years and has caused a dead spot in the Gulf of Mexico, where the Mississippi empties. Intensive agriculture also depletes the fertility of the land over time, potentially leading to desertification.


A field of ripening barleyThe patent protection given to companies that develop new types of seed using genetic engineering has allowed seed to be licensed to farmers in much the same way that computer software is licensed to users. This has changed the balance of power in favor of the seed companies, allowing them to dictate terms and conditions previously unheard of. The Indian activist and scientist Vandana Shiva argues that these companies are guilty of biopiracy.

Soil conservation and nutrient management have been important concerns since the 1950s, with the most advanced farmers taking a stewardship role with the land they use. However, increasing contamination of waterways and wetlands by nutrients like nitrogen and phosphorus are concerns that can only be addressed by "enlightenment" of farmers and/or far stricter law enforcement in many countries.

Increasing consumer awareness of agricultural issues has led to the rise of community-supported agriculture, local food movement, "Slow Food", and commercial organic farming.

Ancient origins
Developed independently by geographically distant populations, systematic agriculture first appeared in Southwest Asia in the Fertile Crescent, particularly in modern-day southern Iraq and Syria. Around 9500 BC, proto-farmers began to select and cultivate food plants with desired characteristics. Though there is evidence of earlier sporadic use of wild cereals, it was not until after 9500 BC that the eight so-called founder crops of agriculture appear: first emmer and einkorn wheat, then hulled barley, peas, lentils, bitter vetch, chick peas and flax.

By 7000 BC, small-scale agriculture reached Egypt. From 7000 BC the Indian subcontinent saw farming of wheat and barley, attested by archaeological excavation at Mehrgarh in Balochistan. By 6000 BC, mid-scale farming was entrenched on the banks of the Nile River. About this time, agriculture was developed independently in the Far East, with rice, rather than wheat, as the primary crop. Chinese and Indonesian farmers went on to domesticate mung, soy, azuki and taro. To complement these new sources of carbohydrates, highly organized net fishing of rivers, lakes and ocean shores in these areas brought in great volumes of essential protein.

By 5000 BC, the Sumerians had developed core agricultural techniques including large scale intensive cultivation of land, mono-cropping, organized irrigation, and use of a specialized labour force, particularly along the waterway now known as the Shatt al-Arab, from its Persian Gulf delta to the confluence of the Tigris and Euphrates. Domestication of wild aurochs and mouflon into cattle and sheep, respectively, ushered in the large-scale use of animals for food/fiber and as beasts of burden. The shepherd joined the farmer as an essential provider for sedentary and semi-nomadic societies.

Maize, manioc, and arrowroot were first domesticated in the Americas as far back as 5300 BC.[1] The potato, tomato, pepper, squash, several varieties of bean, Canna, tobacco and several other plants were also developed in the New World, as was extensive terracing of steep hillsides in much of Andean South America.

In later years, the Greeks and Romans built on techniques pioneered by the Sumerians but made few fundamentally new advances. The Greeks and Macedonians struggled with very poor soils, yet managed to become dominant societies for years. The Romans were noted for an emphasis on the cultivation of crops for trade.


Sumerian Harvester's sickle, 3000 BCE. Baked clay. Field Museum.
[edit] Agriculture in the Middle Ages
During the Middle Ages, Muslim farmers in North Africa and the Near East developed and disseminated agricultural technologies including irrigation systems based on hydraulic and hydrostatic principles, the use of machines such as norias, and the use of water raising machines, dams, and reservoirs. Muslims also wrote location-specific Farming manuals, and were instrumental in the wider adoption of crops including sugar cane, rice, citrus fruit, apricots, cotton, artichokes, aubergines, and saffron. Muslims also brought lemons, oranges, cotton, almonds, figs and sub-tropical crops such as bananas to Spain.


[edit] Renaissance to present day

A tractor ploughing an alfalfa fieldThe invention of a three field system of crop rotation during the Middle Ages, and the importation of the Chinese-invented moldboard plow, vastly improved agricultural efficiency.

After 1492, a global exchange of previously local crops and livestock breeds occurred. Key crops involved in this exchange included the tomato, maize, potato, cocoa, tobacco, and coffee going from the New World to the Old, and, primarily, several varieties of wheat and spice going from the Old World to the New. The most important animal exportation was that of the horse from the Old World to the New. Although not usually a food animal, the horse (including donkeys and ponies) quickly filled essential production roles on the farm.

By the early 1800s, agricultural techniques, implements, seed stocks and cultivars had so improved that yield per land unit was many times that seen in the Middle Ages. With the rapid rise of mechanization in the late 19th and 20th centuries, particularly in the form of the tractor, farming tasks could be done with a speed and on a scale previously impossible. These advances have led to efficiencies enabling certain modern farms in the United States, Argentina, Israel, Germany, and a few other nations to output volumes of high quality produce per land unit at what may be the practical limit.


Agricultural output in 2005In 2005, China was the largest producer of agricultural output with almost one-sixth world share followed by the EU, India and the USA, reports the International Monetary Fund.

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