From Wikipedia, the free encyclopedia
Agriculture refers to the production of agricultural goods through the growing of plants and the raising of domesticated animals. The study of agriculture is known as agricultural science. The related practice of gardening is studied in horticulture.
Agriculture encompasses a wide variety of specialties. Cultivation of crops on arable land and the pastoral herding of livestock on rangeland remain at the foundation of agriculture. In the past century a distinction has been made between sustainable agriculture and intensive farming. Modern agronomy, plant breeding, pesticides and fertilizers, and technological improvements have sharply increased yields from cultivation. Selective breeding and modern practices in animal husbandry such as intensive pig farming (similar practices applied to the chicken) have similarly increased the output of meat. The more exotic varieties of agriculture include aquaculture and tree farming.
The major agricultural products can be broadly grouped into foods, fibers, fuels, raw materials,
legal and illegal drugs, and an assortment of ornamental or otherwise
exotic products. In recent years plants have been used to grow biofuels, biopharmaceuticals, and bioplastic.[1] as well as pharmaceuticals.[2] Specific foods include cereals, (vegetables, fruits, and meat. Fibers include (cotton, wool, hemp, silk and flax). Raw materials include lumber and bamboo. Drugs include tobacco, marijuana, opium, cocaine), and other useful materials such as resins. Biofuels include methane from biomass, ethanol, and biodiesel. Cut flowers, nursery plants, tropical fish and birds for the pet trade are some of the ornamental products.
The history of agriculture has played a major role in human history, as agricultural progress has been a crucial factor in worldwide socio-economic change. Wealth-building and militaristic specializations rarely seen in hunter-gatherer
cultures are commonplace in societies which practice agriculture. So,
too, are arts such as epic literature and monumental architecture, as
well as codified legal systems. When farmers became capable of
producing food beyond the needs of their own families, others in their
society were freed to devote themselves to projects other than food
acquisition. Historians and anthropologists have long argued that the
development of agriculture made civilization possible.
In 2007, an estimated 35 percent of the world's workers were
employed in agriculture (from 42% in 1996). However, the relative
significance of farming has dropped steadily since the beginning of industrialization, and in 2003 – for the first time in history – the services sector overtook agriculture as the economic sector employing the most people worldwide.[3]
Despite the fact that agriculture employs over one-third of the world's
population, agricultural production accounts for less than five percent
of the gross world product (an aggregate of all gross domestic products).[4]
Overview
The amount of workforce dedicated to agriculture tends to decrease
Agriculture has played a key role in the development of human civilization—it is widely believed that the domestication of plants and animals allowed humans to settle and give up their previous hunter-gatherer lifestyle during the Neolithic Revolution. Until the Industrial Revolution,
the vast majority of the human population labored in agriculture.
Development of agricultural techniques has steadily increased
agricultural productivity, and the widespread diffusion of these
techniques during a time period is often called an agricultural revolution.
A remarkable shift in agricultural practices has occurred over the past
century in response to new technologies. In particular, the Haber-Bosch method for synthesizing ammonium nitrate made the traditional practice of recycling nutrients with crop rotation and animal manure less necessary. Synthetic nitrogen, along with mined rock phosphate, pesticides and mechanization, have greatly increased crop yields
in the early 20th century. Increased supply of grains has led to
cheaper livestock as well. Further, global yield increases were
experienced later in the 20th century when high-yield varieties of common staple grains such as rice, wheat, and corn were introduced as a part of the Green Revolution.
The Green Revolution exported the technologies (including pesticides
and synthetic nitrogen) of the developed world out to the developing
world. Thomas Malthus
famously predicted that the Earth would not be able to support its
growing population, but technologies such as the Green Revolution have
allowed the world to produce a surplus of food.[5]
Agricultural output in 2005
Many governments have subsidized agriculture to ensure an adequate food supply. These agricultural subsidies are often linked to the production of certain commodities such as wheat, corn, rice, soybeans, and milk. These subsidies, especially when done by developed countries have been noted as protectionist, inefficient, and environmentally damaging.[6] In the past century agriculture has been characterized by enhanced productivity, the use of synthetic fertilizers and pesticides, selective breeding, mechanization, water contamination, and farm subsidies. Proponents of organic farming such as Sir Albert Howard
argued in the early 1900s that the overuse of pesticides and synthetic
fertilizers damages the long-term fertility of the soil. While this
feeling lay dormant for decades, as environmental awareness has increased recently there has been a movement towards sustainable agriculture by some farmers, consumers, and policymakers. In recent years there has been a backlash against perceived external environmental effects of mainstream agriculture, particularly regarding water pollution[7], resulting in the organic movement. One of the major forces behind this movement has been the European Union, which first certified organic food in 1991 and began reform of its Common Agricultural Policy (CAP) in 2005 to phase out commodity-linked farm subsidies[8], also known as decoupling. The growth of organic farming has renewed research in alternative technologies such as integrated pest management and selective breeding. Recent mainstream technological developments include genetically modified food.
As of late 2007, several factors have pushed up the price of grain
used to feed poultry and dairy cows and other cattle, causing higher
prices of wheat (up 58%), soybean (up 32%), and maize (up 11%) over the
year.[9][10] Food riots have recently taken place in many countries across the world.[11][12][13] An epidemic of stem rust on wheat caused by race UG99 is currently spreading across Africa and into Asia and is causing major concern.[14][15][16] Approximately 40% of the world's agricultural land is seriously degraded.[17] In Africa,
if current trends of soil degradation continue, the continent might be
able to feed just 25% of its population by 2025, according to UNU's Ghana-based Institute for Natural Resources in Africa.[18]
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.[19]
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.
It has been suggested that genetic engineers may some day develop transgenic plants which would allow for irrigation, drainage, conservation,
sanitary engineering, and maintaining or increasing yields while
requiring fewer fossil fuel derived inputs than conventional crops.[20]
Such developments would be particularly important in areas which are
normally arid and rely upon constant irrigation, and on large scale
farms. These possibilities are questioned by ecologists and economists
concerned with unsustainable GMO practices such as terminator seeds,[21][22] and a January 2008 report shows that GMO practices have failed to address sustainability issues.[23] While there has been some research on sustainability using GMO crops, at least one hyped and promonant multi-year attempt by Monsanto
has been unsuccessful, though during the same period traditional
breeding techniques yielded a more sustainable variety of the same crop.[24]
Additionally, a survey by the bio-tech industry of subsistence farmers
in Africa to discover what GMO research would most benefit sustainable
agriculture only identified non-transgenic issues as areas needing to
be addressed.[25]
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
Classical
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