Agriculture is the process of producing food, feed, fiber and other desired products by cultivation of certain plants and the raising of domesticated animals
(livestock). Agriculture is also known as farming.
More people in the world are involved in
agriculture as their primary economic activity than in any other.
Overview
Agriculture can refer 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 commercial
agriculture, 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, what is more formally known as agricultural science.
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 labo(u)r requirements. The developing world generally produce 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 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 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, 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, 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. In
the early 1900s, 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] (http://www.greatachievements.org/greatachievements/ga_7_2.html). 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-stock given
to some animals that can cause Bovine
Spongiform Encephalopathy in cattle.
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
Documenting and explaining the origins of
agriculture is a problem addressed by archaeologists. Archaeobotanists have identified that the cultivation and selection of
specific characteristics such as a semi-tough rachis and larger seeds (such that there were genetic changes in the plants) took place soon after the Younger Dryas in the early Holocene
in the Levant region of the Fertile Crescent. There is earlier evidence: for example grains of rye
with domestic traits have been recovered from Epi-Palaeolithic
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 isn't until ca. 8,500 BC, in archaeological cultures referred to as Pre-Pottery Neolithic B (PPNB), where there is the first definite evidence for the emergence of a subsistence economy that
was dependent on domesticated of plants (and animals). In these contexts lie the origins of the eight so-called founder crops of agriculture: firstly emmer, einkorn, 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. 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 by ca. 5,000
BC.
The reasons for the earliest introduction of farming may have included climate
change, but possibly also social reasons (e.g. accumulation of food surplus for competitive gift-giving). Most certainly there
was a gradual transition from a hunter-gatherer economy to an
agricultural one via 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
be instrumental. In addition to emergence of farming in the Fertile
Crescent, the agriculture appeared by at least 7,000 BC (and possibly earlier) in southeast Asia (rice) and, somewhat later, in Central America (maize, squash). 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. Intensive farming allows a much greater density of population than can be
supported by hunting and gathering. It also allows 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 food production was the
crucial factor in the rise of standing armies.
The invention of a three field system of crop rotation during in the Middle
Ages vastly improved early agriculture 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 in the New and vice versa.
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
Methods
Crops
World production of major crops in 2002
In millions of metric tons, based on USDA estimates:
- Maize 624
- Wheat 570
- Rice 381.1
- Soybeans 196.5
- Cotton 96.5
However, grazing grass and animal feed-crop production must exceed the total of those four crops.
Crop improvement
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]
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
External links
|
