Agriculture

Agriculture refers to the production of food, feed, fiber and other goods by the systematic growing of plants, animals and other life forms. The broad field of agricultural research is called agricultural science. Agriculture encompasses many subjects, including aquaculture, cultivation, animal husbandry, and horticulture. Each of these subjects can be further partitioned: for example, cultivation includes both organic farming and intensive farming, and animal husbandry includes ranching, herding, and intensive pig farming. Agricultural products include fodder, (starch, sugar, alcohols and resins), fibers (cotton, wool, hemp, silk and flax), fuels (methane from biomass, ethanol, 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).

As of 2006, an estimated 36 percent of the world's workers are employed in agriculture (down from 42% in 1996), making it by far the most common occupation. However, the relative significance of farming has dropped steadily since the beginning of industrialization, and in 2006 – for the first time in history – the services sector overtook agriculture as the economic sector employing the most people worldwide. Also, agricultural production accounts for less than five percent of the gross world product (an aggregate of all gross domestic products).

Practices

Agricultural practices lie on a spectrum dependent upon the intensity and technology of the methods. At the one end lies the subsistence farmer who farms a small area with limited inputs and produces only enough food to meet the needs of his or her family. At the other end lies intensive agriculture which includes traditional labor intensive farming (e.g. South-East Asia rice paddies), and modern agriculture which includes industrial agriculture, organic farming and sustainable farming. Industrial agriculture involves large fields and/or numbers of animals, high resource inputs (pesticides, fertilizers, etc.), and a high level of mechanization. These operations achieve economies of scale and require large amounts of capital in the form of land and machinery.

The twentieth century saw 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, analysis of soil makeup and nutritional needs of farm animals.

Mechanization has increased farm efficiency and productivity in most regions of the world, due especially to the tractor and various "gins" (short for "engine") such as the cotton gin, semi-automatic balers and threshers and, above all, the combine (see agricultural machinery). 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. By 1999, due to advances in agricultural technology, a single farmer could feed over 130 people.

A tractor ploughing an alfalfa field

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 on an accelerated schedule. Genetic engineering of plants has proven controversial, particularly in the case of herbicide-resistant plants.

Genetic engineers at companies such as Monsanto are working to 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 processing, packing and marketing of agricultural products are closely related activities also influenced by science. Methods of quick-freezing and dehydration have increased the markets for many farm products (see food preservation and meat packing industry).

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

Airplanes, helicopters, trucks, tractors, and combines are used in Western (and, increasingly, Eastern) 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.

In recent years, some aspects of intensive industrial agriculture have been the subject of increasing debate. 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 over the effect of intensive agriculture on the environment.

A field of ripening barley

The 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.

Etymology

The word agriculture is the English adaptation of Latin agricultūra, from ager, "a field", and cultūra, "cultivation" in the strict sense of "tillage of the soil". Thus, a literal reading of the word yields "tillage of a field / of fields".

History

Main article: History of agriculture

Sumerian Harvester's sickle, 3000 BCE. Baked clay. Field Museum.

Mehrgarh, one of the most important Neolithic (7000 BCE to 3200 BCE) sites in archaeology, lies on the "Kachi plain of Baluchistan, Pakistan, and is one of the earliest sites with evidence of farming (wheat and barley) and herding (cattle, sheep and goats) in South Asia."[1]

Located near the Bolan Pass, to the west of the Indus River valley and between the present-day Pakistani cities of Quetta, Kalat and Sibi, Mehrgarh was discovered in 1974 by an archaeological team directed by French archaeologist Jean-François Jarrige, and was excavated continuously between 1974 and 1986. The earliest settlement at Mehrgarh — in the northeast corner of the 495-acre site — was a small farming village dated between 7000 BCE–5500 BCE.

Ancient origins

Further information: Neolithic Revolution

File:Ancient egyptian farmer.gif

Ancient Egyptian farmer, copied from archaeologically preserved specimen by a modern artist guessing at original colors.
Source: http://www.kingtutone.com

Developed independently by geographically distant populations, systematic agriculture first appeared in Southwest Asia in the Fertile Crescent, particularly in modern-day Iraq and Syria/Israel. Around 9500 BCE, 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 BCE 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 BCE, small-scale agriculture reached Egypt. From at least 7000 BCE the Indian subcontinent saw farming of wheat and barley, as attested by archaeological excavation at Mehrgarh in Balochistan. By 6000 BCE, mid-scale farming was entrenched on the banks of the Nile. 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. Collectively, these new methods of farming and fishing inaugurated a human population boom dwarfing all previous expansions, and is one that continues today.

By 5000 BCE, 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 5200 BCE. [3] 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.

File:Al-jazari pump.png

A valve-operated reciprocating suction piston pump water-raising machine with a crankshaft-connecting rod mechanism invented by al-Jazari.

Agriculture in the Middle Ages

Main article: Muslim Agricultural Revolution

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. They 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.

Renaissance to present day

Further information: British Agricultural Revolution and Green Revolution

A tractor ploughing an alfalfa field

The 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 and tobacco going from the New World to the Old, and several varieties of wheat, spices, coffee, and sugar cane going from the Old World to the New. The most important animal exportations from the Old World to the New were those of the horse and dog (dogs were already present in the pre-Columbian Americas but not in the numbers and breeds suited to farm work). Although not usually food animals, the horse (including donkeys and ponies) and dog quickly filled essential production roles on western hemisphere farms.

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.

In 2005, the agricultural output of China was the largest in the world, accounting for almost one-sixth world share followed by the EU, India and the USA, according to the International Monetary Fund.

Crops

World production of major crops in 2004

Specific crops are cultivated in distinct growing regions throughout the world. In millions of metric tons, based on FAO estimates.

Top agricultural products, by crop types (million metric tons) 2004 data
Cereals	2,263
Vegetables and melons	866
Roots and Tubers	715
Milk	619
Fruit	503
Meat	259
Oilcrops	133
Fish (2001 estimate)	130
Eggs	63
Pulses	60
Vegetable Fiber	30
Source: Food and Agriculture Organization (FAO)

Top agricultural products, by individual crops (million metric tons) 2004 data
Sugar Cane	1,324
Maize	721
Wheat	627
Rice	605
Potatoes	328
Sugar Beet	249
Soybean	204
Oil Palm Fruit	162
Barley	154
Tomato	120
Source: Food and Agriculture Organization (FAO)

Crop alteration

Main article: Plant breeding

Tractor and Chaser Bin

An agricultural scientist records corn growth

Netting protecting wine grapes from birds

Domestication of plants has, over the centuries increased yield, improved disease resistance and drought tolerance, eased harvest and improved the taste and nutritional value of crop plants. Careful selection and breeding have had enormous effects on the characteristics of crop plants. Plant breeders use greenhouses (known as glasshouses or hothouses in some areas) and other techniques to get as many as three generations of plants per year towards the continued effort of improvement. Plant selection and breeding in the 1920s and 1930s improved pasture (grasses and clover) in New Zealand. Extensive X-ray an ultraviolet induced mutagenesis efforts (i.e. primitive genetic engineering) during the 1950s produced the modern commercial varieties of grains such as wheat, corn and barley.

For example, average yields of corn (maize) in the USA have increased from around 2.5 tons per hectare (t/ha) (40 bushels per acre) in 1900 to about 9.4 t/ha (150 bushels per acre) in 2001. Similarly, worldwide average wheat yields have increased from less than 1 t/ha in 1900 to more than 2.5 t/ha in 1990. South American average wheat yields are around 2 t/ha, African under 1 t/ha, Egypt and Arabia up to 3.5 to 4 t/ha with irrigation. In contrast, the average wheat yield in countries such as France is over 8 t/ha. Variation in yields are due mainly to variation in climate, genetics, and the level of intensive farming techniques (use of fertilizers, chemical pest control, growth control to avoid lodging).

After mechanical tomato-harvesters were developed in the early 1960s, agricultural scientists bred tomatoes that were more resistant to mechanical handling. These varieties have been criticized as being harder and having poor texture. More recently, genetic engineering has begun to be employed in large parts of the world to speed up the selection and breeding process. One widely used modification is a herbicide resistance gene that allows plants to tolerate exposure to glyphosate, a non-systemic (i.e kills all plants) chemical used to control weeds in a crop such as oilseed rape. Normally, expensive systemic herbicides would have to be applied to kill the weeds without harming the crop. Relatively cheap and safe glyphosate may be applied to the modified crops, efficiently killing weeds without harming the resistant crop. Another modification causes the plant to produce a toxin to reduce damage from insects (c.f. Starlink). This, in contrast, requires fewer insecticides to be applied to the crop.

Aquaculture, the farming of fish, shrimp, and algae, is closely associated with agriculture.

Apiculture, the culture of bees, traditionally for honey—increasingly for crop pollination.

See also : botany, List of domesticated plants, List of vegetables, List of herbs, List of fruit

Livestock

Main article: Livestock

The farming practices of livestock vary dramatically world-wide and between different types of animals. Livestock are generally kept in an enclosure, are fed by human-provided food and are intentionally bred, but some livestock are not enclosed, or are fed by access to natural foods, or are allowed to breed freely, or all three. Approximately 68% of all agricultural land is used in the production of livestock as permanent pastures.

Environmental impact

File:Soil erosion1.jpg

Severe soil erosion in a wheat field near Washington State University, US (c.2005)

Agriculture may often cause environmental problems because it changes natural environments and produces harmful by-products. Some of the negative effects are:

• Loss of biodiversity
• Surplus of nitrogen and phosphorus in rivers and lakes
• Detrimental effects of herbicides, fungicides, insecticides, and other biocides
• Conversion of natural ecosystems of all types into arable land
• Consolidation of diverse biomass into a few species
• Soil erosion
• Depletion of minerals in the soil
• Particulate matter, including ammonia and ammonium off-gassing from animal waste contributing to air pollution
• Weed Science - feral plants and animals
• Odor from agricultural waste
• Soil salination

According to the United Nations, the livestock sector (primarily cows, chickens, and pigs) emerges as one of the top two or three most significant contributors to our most serious environmental problems, at every scale from local to global. Livestock production occupies 70% of all land used for agriculture, or 30% of the land surface of the planet.It is one of the largest sources of greenhouse gases—responsible for 18% of the world’s greenhouse gas emissions as measured in CO₂ equivalents. By comparison, all transportation emits 13.5% of the CO₂. It produces 65% of human-related nitrous oxide (which has 296 times the global warming potential of CO₂) and 37% of all human-induced methane (which is 23 times as warming as CO₂). It also generates 64% of the ammonia, which contributes to acid rain and acidification of ecosystems.

Genetic erosion in crop and livestock biodiversity

See also: Genetic erosion and Agricultural biodiversity

Genetic erosion in crops and livestock biodiversity is propelled by several major factors such as variety replacement, land clearing, overexploitation of species, population pressure, environmental degradation, overgrazing, policy and changing agricultural systems.

The main factor, however, is the replacement of local varieties of domestic plants and animals by high yielding or exotic varieties or species. A large number of varieties can also often be dramatically reduced when commercial varieties (including GMOs) are introduced into traditional farming systems. Many researchers believe that the main problem related to agro-ecosystem management is the general tendency towards genetic and ecological uniformity imposed by the development of modern agriculture.

In agriculture and animal husbandry, the green revolution popularized the use of conventional hybridization to increase yield many folds by creating "high-yielding varieties". Often the handful of breeds of plants and animals hybridized originated in developed countries and were further hybridized with local varieties in the rest of the developing world to create high yield strains resistant to local climate and diseases. Hybridization of local breeds to improve performance may lead to the loss of the local breed over time and consequently the loss of the genetic material that adapted that breed specifically to the local conditions. When viewed across the world as a whole, the consequent loss in genetic diversity and biodiversity could be placing the food supply in jeopardy, as a highly specialized breed may not contain sufficient genetic material to adapt to new diseases or environments even with an intensive breeding program.

A Genetically Modified Organism (GMO) is an organism whose genetic material has been altered using the genetic engineering techniques generally known as recombinant DNA technology. Genetic Engineering today has become another serious and alarming cause of genetic pollution because artificially created and genetically engineered plants and animals in laboratories, which could never have evolved in nature even with conventional hybridization, can live and breed on their own and what is even more alarming interbreed with naturally evolved wild varieties. Genetically Modified (GM) crops today have become a common source for genetic pollution, not only of wild varieties but also of other domesticated varieties derived from relatively natural hybridization.

Policy

Main article: Agricultural policy

Agricultural policy focuses on the goals and methods of agricultural production. At the policy level, common goals of agriculture include:

• Food safety: Ensuring that the food supply is free of contamination.
• Food security: Ensuring that the food supply meets the population's needs.
• Food quality: Ensuring that the food supply is of a consistent and known quality.
• Poverty Reduction
• Conservation
• Environmental impact
• Economic stability

Agriculture and petroleum

Further information: Peak oil § Agriculture and population limits

Since the 1940s, agriculture has dramatically increased its productivity, due largely to the use of petrochemical derived pesticides, fertilizers, and increased mechanization. This has allowed world population to grow more than double over the last 50 years. Every energy unit delivered in food grown using modern techniques requires over ten energy units to produce and deliver. The vast majority of this energy input comes from fossil fuel sources. Because of modern agriculture's current heavy reliance on petrochemicals and mechanization, there are warnings that the ever decreasing supply of oil (the dramatic nature of which is known as peak oil) will inflict major damage on the modern industrial agriculture system, and could cause large food shortages.

Oil shortages are one of several factors making organic agriculture and other sustainable farming methods necessary. This conversion is now occurring, but the reconditioning of soil to restore nutrients lost during the use of monoculture agriculture techniques made possible by petroleum-based technology will take time. Some farmers using modern organic-farming methods have reported yields as high as those available from conventional farming (but without the use of fossil-fuel-intensive artificial fertilizers or pesticides).

Farmers have also begun raising crops such as corn for non-food use in an effort to help mitigate peak oil. This has lead to a 60% rise in wheat prices recently, and has been indicated as a possible precursor to "serious social unrest in developing countries." Such situations would be exacerbated in the event of future rises in food and fuel costs, factors which have already impacted the ability of charitable donors to send food aid to starving populations.

Agriculture safety and health

Satellite image of circular crop fields characteristic of center pivot irrigation in Haskell County, Kansas in late June 2001. Healthy, growing crops are green. Corn is growing leafy stalks, but Sorghum, which resembles corn, grows more slowly and is much smaller and therefore paler. Wheat is a brilliant gold as harvest occurs in June. Brown fields have been recently harvested and plowed under or lie fallow for the year.

United States

Agriculture ranks among the most hazardous industries. Farmers are at high risk for fatal and nonfatal injuries, work-related lung diseases, noise-induced hearing loss, skin diseases, and certain cancers associated with chemical use and prolonged sun exposure. Farming is one of the few industries in which the families (who often share the work and live on the premises) are also at risk for injuries, illness, and death.

• In an average year, 516 workers die doing farm work in the U.S. (1992-2005). Of these deaths, 101 are caused by tractor overturns.
• Every day, about 243 agricultural workers suffer lost-work-time injuries, and about 5% of these result in permanent impairment.

Young Workers

Agriculture is the most dangerous industry for young workers, accounting for 42% of all work-related fatalities of young workers in the U.S. between 1992 and 2000. Unlike other industries, half the young victims in agriculture were under age 15.

For young agricultural workers aged 15–17, the risk of fatal injury is four times the risk for young workers in other workplaces Agricultural work exposes young workers to safety hazards such as machinery, confined spaces, work at elevations, and work around livestock.

• An estimated 1.26 million children and adolescents under 20 years of age resided on farms in 2004, with about 699,000 of these youth performing work on the farms. In addition to the youth who live on farms, an additional 337,000 children and adolescents were hired to work on U.S. farms in 2004.
• On average, 103 children are killed annually on farms (1990-1996). Approximately 40 percent of these deaths were work-related.
• In 2004, an estimated 27,600 children and adolescents were injured on farms; 8,100 of these injuries were due to farm work.

See also

Main lists: List of basic agriculture topics and List of agriculture topics

• Aeroponics
• Agrocenter
• Apiculture
• Climate change and agriculture
• Dismal Science - highlighting the imperative for continuous advancement in agricultural science
• Geoponic
• Green Revolution
• Horticulture
• Hydroponic
• Industrial agriculture
• Integrated Pest Management (IPM)
• List of countries by agricultural output
• List of domesticated animals
• List of subsistence techniques
• List of sustainable agriculture topics
• Organic farming
• Permaculture
• Timeline of agriculture and food technology.

References

• Artz, F. B, (1980), ‘The Mind of the Middle Ages’; Third edition revised; The University of Chicago Press,
• Bolens, L. (1997), `Agriculture’ in Encyclopedia of the history of Science, technology, and Medicine in Non Western Cultures, Editor: Helaine Selin; Kluwer Academic Publishers. Dordrecht/Boston/London, pp 20-2
• Collinson, M. (editor): A History of Farming Systems Research. CABI Publishing, 2000. ISBN 0-85199-405-9
• Crosby, Alfred W.: The Columbian Exchange : Biological and Cultural Consequences of 1492. Praeger Publishers, 2003 (30th Anniversary Edition). ISBN 0-275-98073-1
• Davis, Donald R., and Hugh D. Riordan (2004) Changes in USDA Food Composition Data for 43 Garden Crops, 1950 to 1999. Journal of the American College of Nutrition, Vol. 23, No. 6, 669-682.
• Friedland, William H. and Amy Barton (1975) Destalking the Wily Tomato: A Case Study of Social Consequences in California Agricultural Research. Univ. California at Sta. Cruz, Research Monograph 15.
• Saltini A.Storia delle scienze agrarie, 4 vols, Bologna 1984-89, ISBN 88-206-2412-5, ISBN 88-206-2413-3, ISBN 88-206-2414-1, ISBN 88-206-2414-X
• Watson, A.M (1974), ‘The Arab agricultural revolution and its diffusion’, in The Journal of Economic History, 34,
• Watson, A.M (1983), ‘ Agricultural Innovation in the Early Islamic World’, Cambridge University Press
• Wells, Spencer: The Journey of Man : A Genetic Odyssey. Princeton University Press, 2003. ISBN 0-691-11532-X
• Wickens, G.M.(1976), ‘What the West borrowed from the Middle east’, in Introduction to Islamic Civilization, edited by R.M. Savory, Cambridge University Press, Cambridge

Coffee Plantation in São João do Manhuaçu City - Minas Gerais State - Brazil.

External links

• UKAgriculture.com - Advance the education of the public in all aspects of agriculture, the countryside and the rural economy

• National Institute for Occupational Safety and Health - Agriculture Page

• Research on the role of Agriculture in Poverty Reduction from the Overseas Development Institute