Agriculture

Agriculture is the process of producing food, feed, fiber and many other desired products by the cultivation of certain plants and the raising of domesticated animals ( livestock). The practice of agriculture is also known as " farming", while scientists, inventors and others devoted to improving farming methods and implements are also said to be engaged in agriculture.

More people in the world are involved in agriculture as their primary economic activity than in any other, yet it only accounts for four percent of the world's GDP.

Overview

Agriculture sometimes refers to subsistence agriculture, the production of enough food to meet just the needs of the farmer/ agriculturalist and his/her family. It may also refer to industrial agriculture, (often referred to as factory farming) long prevalent in developed nations and increasingly so elsewhere, which consists of obtaining financial income from the cultivation of land to yield produce, the commercial raising of animals ( animal husbandry), or both.

Agriculture is also short for the study of the practice of agriculture—more formally known as agricultural science. Agricultural students are known (sometimes derisively) as "Aggies".

Increasingly, in addition to food for humans and animal feeds, agriculture produces goods such as cut flowers, ornamental and nursery plants, timber or lumber, fertilizers, animal hides, leather, industrial chemicals ( starch, sugar, ethanol, alcohols and plastics), fibers ( cotton, wool, hemp, and flax), fuels ( methane from biomass, biodiesel) and both legal and illegal drugs ( biopharmaceuticals, tobacco, marijuana, opium, cocaine). Genetically engineered plants and animals produce specialty drugs.

In the Western world, the use of gene manipulation, better management of soil nutrients, and improved weed control have greatly increased yields per unit area. At the same time, the use of mechanization has decreased labour requirements. The developing world generally produces lower yields, having less of the latest science, capital, and technology base.

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. Plant breeding and genetics contribute additionally to farm productivity. Advanced seed engineering has allowed strains of seed to become perfect in every farming situation. Seeds can now germinate faster and adapt to shorter growing seasons in different climates. Present-day seed can resist the spraying of pesticides that kill all green-leaf plants. 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 preservation; Meat packing industry).

Mechanization, the outstanding characteristic of late 19th and 20th century agricultural evolution, 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, mules, oxen, camels, 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, helicopters, trucks and tractors are used in agriculture for seeding, spraying operations for insect and disease control, Aerial topdressing, transporting perishable products, and fighting forest fires. 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.

According to the National Academy of Engineering in the US, 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, where today, due to engineering technology (also, plant breeding and agrichemicals), a single farmer can feed over 130 people [1]. This comes at a cost, however, of large amounts of energy input, from unsustainable, mostly fossil fuel, sources.

Animal husbandry means breeding and raising animals for meat or to harvest animal products (like milk, eggs, or wool) on a continual basis.

In recent years some aspects of industrial intensive 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. There has been increased activity of some people against some farming practices, raising chickens for food being one example. 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 and the end effect is that which happened in the Middle East, were some of the most fertile farmland in the world was turned into a desert by intensive agriculture.

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. Some argue these companies are guilty of biopiracy.

Soil conservation and nutrient management have been important concerns since the 1950s, with the best farmers taking a stewardship role with the land they operate. However, increasing contamination of waterways and wetlands by nutrients like nitrogen and phosphorus are of concern 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, though these yet remain fledgling industries.

History

Archaeobotanists/ Paleoethnobotanists have traced the selection and cultivation of specific food plant characteristics, such as a semi-tough rachis and larger seeds, to just after the Younger Dryas (about 9,500 BC) in the early Holocene in the Levant region of the Fertile Crescent. Limited anthropological and archaeological evidence both indicate a grain- grinding culture farming along the Nile in the 10th millennium BC using the world's earliest known type of sickle blades. There is even earlier evidence for conscious cultivation and seasonal harvest: grains of rye with domestic traits have been recovered from Epi-Palaeolithic (10,000+ BC) contexts at Abu Hureyra in Syria, but this appears to be a localised phenomenon resulting from cultivation of stands of wild rye, rather than a definitive step towards domestication. It is not until ca. 8,500 BC, in middle-Eastern cultures referred to as Pre-Pottery Neolithic B ( PPNB), where there is the first definite evidence for the emergence of a widespread subsistence economy that was dependent on domesticated plants and animals. In these contexts lie the origins of the eight so-called founder crops of agriculture: firstly emmer wheat, einkorn wheat, then hulled barley, pea, lentil, bitter vetch, chick pea and flax. These eight crops occur more or less simultaneously on PPNB sites in this region, although the consensus is that wheat was the first to be sown and harvested on a significant scale. There are many sites that date to between ca. 8,500 BC and 7,500 BC where the systematic farming of these crops contributed the major part of the inhabitants' diet. From the Fertile Crescent agriculture spread eastwards to Central Asia and westwards into Cyprus, Anatolia and, by 7,000 BC, Greece. Farming, principally of emmer and einkorn, reached northwestern Europe via southeastern and central Europe by ca. 4,800 BC (see, among others, Price, D. [ed.] 2000. Europe's First Farmers. Cambridge University Press; Harris, D. [ed.] 1996 The Origins and Spread of Agriculture in Eurasia. UCL Press).

The reasons for the earliest introduction of farming may have included climate change, but possibly there were also social reasons (e.g. accumulation of food surplus for competitive gift-giving). Most certainly there was a gradual transition from hunter-gatherer to agricultural economies after a lengthy period when some crops were deliberately planted and other foods were gathered from the wild. Although localised climate change is the favoured explanation for the origins of agriculture in the Levant, the fact that farming was 'invented' at least three times, possibly more, suggests that social reasons may have been instrumental. In addition to emergence of farming in the Fertile Crescent, agriculture appeared by at least 6,800 BC in East Asia (rice) and, later, in Central and South America (maize, squash). Small scale agriculture also likely arose independently in early Neolithic contexts in India (rice) and Southeast Asia (taro).

Full dependency on domestic crops and animals (i.e. when wild resources contributed a nutritionally insignificant component to the diet) was not until the Bronze Age. If the operative definition of agriculture includes large scale intensive cultivation of land, mono-cropping, organised irrigation, and use of a specialized labour force, the title "inventors of agriculture" would fall to the Sumerians, starting ca. 5,500 BC. Intensive farming allows a much greater density of population than can be supported by hunting and gathering and allows for the accumulation of excess product to keep for winter use or to sell for profit. The ability of farmers to feed large numbers of people whose activities have nothing to do with material production was the crucial factor in the rise of standing armies. The agriculturalism of the Sumerians allowed them to embark on an unprecedented territorial expansion, making them the first empire builders. Not long after, the Egyptians, powered by effective farming of the Nile valley, achieved a population density from which enough warriors could be drawn for a territorial expansion more than tripling the Sumerian empire in area.

The invention of a three field system of crop rotation during the Middle Ages vastly improved agricultural efficiency.

After 1492 the world's agricultural patterns were shuffled in the widespread exchange of plants and animals known as the Columbian Exchange. Crops and animals that were previously only known in the Old World were now transplanted to the New and vice versa. Perhaps most notably, the tomato became a favorite in European cuisine, while certain wheat strains quickly took to western hemisphere soils and became a dietary staple even for native North, Central and South Americans.

By the early 1800s agricultural practices, particularly careful selection of hardy strains and cultivars, had so improved that yield per land unit was many times that seen in the Middle Ages and before, especially in the largely virgin lands of North and South America. With the rapid rise of mechanization in the 20th century, especially in the form of the tractor, the demanding tasks of sowing, harvesting and threshing could be performed with a speed and on a scale barely imaginable before. 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.

Crops

World production of major crops in 2004

In millions of metric tons, based on FAO estimates [2]:

By crop types

Cereals 2,264

Vegetables and melons 866

Roots and Tubers 715

Milk 619

Fruit 503

Meat 259

Oilcrops 133

Fish 130 (2001 estimate)

Eggs 63

Pulses 60

Vegetable Fiber 30

By individual crops

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

Crop improvement

• See main article on Plant breeding

Domestication of plants is done in order to increase yield, improve disease resistance and drought tolerance, ease harvest and to improve the taste and nutritional value and many other characteristics. Centuries of careful selection and breeding have had enormous effects on the characteristics of crop plants. Plant breeders use greenhouses and other techniques to get as many as three generations of plants per year so that they can make improvements all the more quickly.

Plant selection and breeding in the 1920s and '30s improved pasture (grasses and clover) in New Zealand. Extensive radiation 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 (40 bushels per acre) in 1900 to about 9.4 t/ha (150 bushels per acre) in 2001, primarily due to improvements in genetics. 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. Higher yields are due to improvements in genetics, as well as use of intensive farming techniques (use of fertilizers, chemical pest control, growth control to avoid lodging). [Conversion note: 1 bushel of wheat = 60 pounds (lb) ≈ 27.215 kg. 1 bushel of corn = 56 pounds ≈ 25.401 kg]

In industrialized agriculture, crop "improvement" has often reduced nutritional and other qualities of food plants to serve the interests of producers. After mechanical tomato-harvesters were developed in the early 1960s, agricultural scientists bred tomatoes that were harder and less nutritious (Friedland and Barton 1975). In fact, a major longitudinal study of nutrient levels in numerous vegetables showed significant declines in the last 50 years; garden vegetables in the U.S. today contain on average 38 percent less vitamin B2 and 15 percent less vitamin C (Davis and Riordan 2004).

Very recently, genetic engineering has begun to be employed in some parts of the world to speed up the selection and breeding process. The most widely used modification is a herbicide resistance gene that allows plants to tolerate exposure to glyphosate, which is used to control weeds in the crop. A less frequently used but more controversial modification causes the plant to produce a toxin to reduce damage from insects (c.f. Starlink).

There are specialty producers who raise less common types of livestock or plants.

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

Environmental problems

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

• Nitrogen and phosphorus surplus 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.
• Erosion
• Depletion of minerals in the soil
• Particulate matter, including ammonia and ammonium off-gasing from animal waste contributing to air pollution
• Weeds - feral plants and animals
• Odor from agricultural waste
• Soil salination in dry areas.

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.

• Conservation
• Environmental impact
• Economic stability

Agricultural Revolutions

• British Agricultural Revolution
• Green Revolution
• Neolithic Revolution

Methods

There are various methods of agricultural production:

• aeroponics
• aerial topdressing
• agricultural machinery
• animal husbandry
• aquaculture
• beekeeping
• crop rotation
• Concentrated Animal Feeding Operation ( CAFO, factory farming)
• composting
• dairy farming
• detasseling
• domestication
• fencing
• fertilizers
• greenhouse
• harvest
• heliciculture
• hybrid seed
• hydroponics
• Integrated Pest Management ( IPM)
• irrigation
• livestock
• market gardening
• monoculture
• no-till farming
• organic farming
• plant breeding
• Permaculture
• pollination management
• precision farming
• ranching
• season extension
• seed saving
• seed testing
• shepherding
• subsistence farming
• succession planting
• sustainable agriculture
• terracing
• vegetable farming
• tillage
• weed control