Agriculture

Agriculture encompasses crop and livestock production, aquaculture, fisheries, and forestry for food and non-food products.[1] Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to live in cities. While humans started gathering grains at least 105,000 years ago, nascent farmers only began planting them around 11,500 years ago. Sheep, goats, pigs, and cattle were domesticated around 10,000 years ago. Plants were independently cultivated in at least 11 regions of the world. In the 20th century, industrial agriculture based on large-scale monocultures came to dominate agricultural output.

As of 2021, small farms produce about one-third of the world's food, but large farms are prevalent.[2] The largest 1% of farms in the world are greater than 50 hectares (120 acres) and operate more than 70% of the world's farmland.[2] Nearly 40% of agricultural land is found on farms larger than 1,000 hectares (2,500 acres).[2] However, five of every six farms in the world consist of less than 2 hectares (4.9 acres) and take up only around 12% of all agricultural land.[2] Farms and farming greatly influence rural economics and greatly shape rural society, effecting both the direct agricultural workforce and broader businesses that support the farms and farming populations.

The major agricultural products can be broadly grouped into foods, fibers, fuels, and raw materials (such as rubber). Food classes include cereals (grains), vegetables, fruits, cooking oils, meat, milk, eggs, and fungi. Global agricultural production amounts to approximately 11 billion tonnes of food,[3] 32 million tonnes of natural fibres[4] and 4 billion m3 of wood.[5] However, around 14% of the world's food is lost from production before reaching the retail level.[6]

Modern agronomy, plant breeding, agrochemicals such as pesticides and fertilizers, and technological developments have sharply increased crop yields, but also contributed to ecological and environmental damage. Selective breeding and modern practices in animal husbandry have similarly increased the output of meat, but have raised concerns about animal welfare and environmental damage. Environmental issues include contributions to climate change, depletion of aquifers, deforestation, antibiotic resistance, and other agricultural pollution. Agriculture is both a cause of and sensitive to environmental degradation, such as biodiversity loss, desertification, soil degradation, and climate change, all of which can cause decreases in crop yield. Genetically modified organisms are widely used, although some countries ban them.


Etymology and scope
Further information: Horticulture § Scope
The word agriculture is a late Middle English adaptation of Latin agricultūra, from ager 'field' and cultūra 'cultivation' or 'growing'.[7] While agriculture usually refers to human activities, certain species of ant,[8][9] termite and beetle have been cultivating crops for up to 60 million years.[10] Agriculture is defined with varying scopes, in its broadest sense using natural resources to "produce commodities which maintain life, including food, fiber, forest products, horticultural crops, and their related services".[11] Thus defined, it includes arable farming, horticulture, animal husbandry and forestry, but horticulture and forestry are in practice often excluded.[11] It may also be broadly decomposed into plant agriculture, which concerns the cultivation of useful plants,[12] and animal agriculture, the production of agricultural animals.[13]

History

Centres of origin, as numbered by Nikolai Vavilov in the 1930s.
Area 3 is no longer recognised as a centre of origin
New Guinea (area P) was identified more recently.
[14][15]
Main article: History of agriculture
Origins
Main article: Neolithic Revolution
The development of agriculture enabled the human population to grow many times larger than could be sustained by hunting and gathering.[16] Agriculture began independently in different parts of the globe,[17] and included a diverse range of taxa, in at least 11 separate centers of origin.[14] Wild grains were collected and eaten from at least 105,000 years ago.[18] In the Paleolithic Levant, 23,000 years ago, cereals cultivation of emmer, barley, and oats has been observed near the sea of Galilee.[19][20] Rice was domesticated in China between 11,500 and 6,200 BC with the earliest known cultivation from 5,700 BC,[21] followed by mung, soy and azuki beans. Sheep were domesticated in Mesopotamia between 13,000 and 11,000 years ago.[22] Cattle were domesticated from the wild aurochs in the areas of modern Turkey and Pakistan some 10,500 years ago.[23] Pig production emerged in Eurasia, including Europe, East Asia and Southwest Asia,[24] where wild boar were first domesticated about 10,500 years ago.[25] In the Andes of South America, the potato was domesticated between 10,000 and 7,000 years ago, along with beans, coca, llamas, alpacas, and guinea pigs. Sugarcane and some root vegetables were domesticated in New Guinea around 9,000 years ago. Sorghum was domesticated in the Sahel region of Africa by 7,000 years ago. Cotton was domesticated in Peru by 5,600 years ago,[26] and was independently domesticated in Eurasia. In Mesoamerica, wild teosinte was bred into maize (corn) from 10,000 to 6,000 years ago.[27][28][29] The horse was domesticated in the Eurasian Steppes around 3500 BC.[30] Scholars have offered multiple hypotheses to explain the historical origins of agriculture. Studies of the transition from hunter-gatherer to agricultural societies indicate an initial period of intensification and increasing sedentism; examples are the Natufian culture in the Levant, and the Early Chinese Neolithic in China. Then, wild stands that had previously been harvested started to be planted, and gradually came to be domesticated.[31][32][33]

Civilizations

Map of the world showing approximate centers of origin of agriculture and its spread in prehistory.[34] DNA studies have shown that agriculture was introduced in Europe by the expansion of the early farmers from Anatolia about 9,000 years ago. [35]
In Eurasia, the Sumerians started to live in villages from about 8,000 BC, relying on the Tigris and Euphrates rivers and a canal system for irrigation. Ploughs appear in pictographs around 3,000 BC; seed-ploughs around 2,300 BC. Farmers grew wheat, barley, vegetables such as lentils and onions, and fruits including dates, grapes, and figs.[36] Ancient Egyptian agriculture relied on the Nile River and its seasonal flooding. Farming started in the predynastic period at the end of the Paleolithic, after 10,000 BC. Staple food crops were grains such as wheat and barley, alongside industrial crops such as flax and papyrus.[37][38] In India, wheat, barley and jujube were domesticated by 9,000 BC, soon followed by sheep and goats.[39] Cattle, sheep and goats were domesticated in Mehrgarh culture by 8,000–6,000 BC.[40][41][42] Cotton was cultivated by the 5th–4th millennium BC.[43] Archeological evidence indicates an animal-drawn plough from 2,500 BC in the Indus Valley civilisation.[44]

In China, from the 5th century BC, there was a nationwide granary system and widespread silk farming.[45] Water-powered grain mills were in use by the 1st century BC,[46] followed by irrigation.[47] By the late 2nd century, heavy ploughs had been developed with iron ploughshares and mouldboards.[48][49] These spread westwards across Eurasia.[50] Asian rice was domesticated 8,200–13,500 years ago – depending on the molecular clock estimate that is used[51]– on the Pearl River in southern China with a single genetic origin from the wild rice Oryza rufipogon.[52] In Greece and Rome, the major cereals were wheat, emmer, and barley, alongside vegetables including peas, beans, and olives. Sheep and goats were kept mainly for dairy products.[53][54]


Agricultural scenes of threshing, a grain store, harvesting with sickles, digging, tree-cutting and ploughing from ancient Egypt. Tomb of Nakht, 15th century BC
In the Americas, crops domesticated in Mesoamerica (apart from teosinte) include squash, beans, and cacao.[55] Cocoa was domesticated by the Mayo Chinchipe of the upper Amazon around 3,000 BC.[56] The turkey was probably domesticated in Mexico or the American Southwest.[57] The Aztecs developed irrigation systems, formed terraced hillsides, fertilized their soil, and developed chinampas or artificial islands. The Mayas used extensive canal and raised field systems to farm swampland from 400 BC.[58][59][60][61][62] In South America agriculture may have begun about 9000 BC with the domestication of squash (Cucurbita) and other plants.[63] Coca was domesticated in the Andes, as were the peanut, tomato, tobacco, and pineapple.[55] Cotton was domesticated in Peru by 3,600 BC.[64] Animals including llamas, alpacas, and guinea pigs were domesticated there.[65] In North America, the indigenous people of the East domesticated crops such as sunflower, tobacco,[66] squash and Chenopodium.[67][68] Wild foods including wild rice and maple sugar were harvested.[69] The domesticated strawberry is a hybrid of a Chilean and a North American species, developed by breeding in Europe and North America.[70] The indigenous people of the Southwest and the Pacific Northwest practiced forest gardening and fire-stick farming. The natives controlled fire on a regional scale to create a low-intensity fire ecology that sustained a low-density agriculture in loose rotation; a sort of "wild" permaculture.[71][72][73][74] A system of companion planting called the Three Sisters was developed in North America. The three crops were winter squash, maize, and climbing beans.[75][76]

Indigenous Australians, long supposed to have been nomadic hunter-gatherers, practised systematic burning, possibly to enhance natural productivity in fire-stick farming.[77] Scholars have pointed out that hunter-gatherers need a productive environment to support gathering without cultivation. Because the forests of New Guinea have few food plants, early humans may have used "selective burning" to increase the productivity of the wild karuka fruit trees to support the hunter-gatherer way of life.[78]

The Gunditjmara and other groups developed eel farming and fish trapping systems from some 5,000 years ago.[79] There is evidence of 'intensification' across the whole continent over that period.[80] In two regions of Australia, the central west coast and eastern central, early farmers cultivated yams, native millet, and bush onions, possibly in permanent settlements.[33][81]

Revolution

Agricultural calendar, c. 1470, from a manuscript of Pietro de Crescenzi
In the Middle Ages, compared to the Roman period, agriculture in Western Europe became more focused on self-sufficiency. The agricultural population under feudalism was typically organized into manors consisting of several hundred or more acres of land presided over by a lord of the manor with a Roman Catholic church and priest.[82]

Thanks to the exchange with the Al-Andalus where the Arab Agricultural Revolution was underway, European agriculture transformed, with improved techniques and the diffusion of crop plants, including the introduction of sugar, rice, cotton and fruit trees (such as the orange).[83]

After 1492, the Columbian exchange brought New World crops such as maize, potatoes, tomatoes, sweet potatoes, and manioc to Europe, and Old World crops such as wheat, barley, rice, and turnips, and livestock (including horses, cattle, sheep and goats) to the Americas.[84]

Irrigation, crop rotation, and fertilizers advanced from the 17th century with the British Agricultural Revolution, allowing global population to rise significantly. Since 1900, agriculture in developed nations, and to a lesser extent in the developing world, has seen large rises in productivity as mechanization replaces human labor, and assisted by synthetic fertilizers, pesticides, and selective breeding. The Haber-Bosch method allowed the synthesis of ammonium nitrate fertilizer on an industrial scale, greatly increasing crop yields and sustaining a further increase in global population.[85][86]

Modern agriculture has raised or encountered ecological, political, and economic issues including water pollution, biofuels, genetically modified organisms, tariffs and farm subsidies, leading to alternative approaches such as the organic movement.[87][88] Unsustainable farming practices in North America led to the Dust Bowl of the 1930s.[89