is the production of food and goods
through farming and forestry. Agriculture was the key development
that led to the rise of human civilization
, with the husbandry
of domesticated animals
plants (i.e. crops
) creating food surpluses
that enabled the development of more
societies. The study of
agriculture is known as agricultural science
Agriculture encompasses a wide variety of specialties and
techniques, including ways to expand the lands suitable for plant
raising, by digging water-channels and other forms of irrigation.
of crops on arable land
and the pastoral herding
remain at the foundation of agriculture.
In the past century there has been increasing concern to identify
and quantify various forms of agriculture. In the developed world
the range usually extends between sustainable agriculture
or organic agriculture
) and intensive farming
(e.g. industrial agriculture
, plant breeding
, and technological improvements have
sharply increased yields from cultivation, and at the same time
have caused widespread ecological damage and negative human health
effects. Selective breeding
modern practices in animal husbandry such as intensive pig farming
practices applied to the chicken
similarly increased the output of meat
have raised concerns about animal
and the health effects of the antibiotics
, and other chemicals commonly used in industrial meat
The major agricultural products can be broadly grouped into
, raw materials
, and an assortment of ornamental or
exotic panget products. In the 2000s, plants have been used to grow
, and pharmaceuticals. Specific foods
. Raw materials
lumber and bamboo. Stimulants include tobacco
. Other useful materials are produced by
plants, such as resins
. Biofuels include
, and biodiesel
. Cut flowers
, tropical fish
and birds for the pet trade are some of the ornamental
In 2007, about one third of the world's workers were employed in
agriculture. Though in 2003 agricultural employees were fewer but
due to the agricultural awareness it increased rapidly in 2008– the
agriculture as the economic sector
employing the most people worldwide. 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
aggregate of all gross domestic
The word agriculture
is the English adaptation of Latin
, from ager
, "a field", and
" in the
strict sense of "tillage
of the soil". Thus,
a literal reading of the word yields "tillage of a field / of
Agriculture has played a key role in the development of human
. 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
remarkable shift in agricultural practices has occurred over the
past century in response to new technologies. In particular, the
method for synthesizing
traditional practice of recycling nutrients with crop rotation
and animal manure
The percent of the human population
working in agriculture has decreased over time.
Synthetic nitrogen, along with mined rock
, have greatly increased
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
of common staple grains such as rice
, and corn (maize
) were introduced as a part of the Green Revolution
. The Green Revolution
exported the technologies (including pesticides and synthetic
nitrogen) of the developed world 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.
Agricultural output in 2005.
Many governments have subsidized agriculture to ensure an adequate
food supply. These agricultural
are often linked to the production of certain
commodities such as wheat
, corn (maize
, and milk
subsidies, especially when instituted by developed countries
have been noted as
, inefficient, and
environmentally damaging. In the past century agriculture has been
characterized by enhanced productivity
the use of synthetic fertilizers
pesticides, selective breeding
, 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
increased in the 2000s there has been a movement towards sustainable agriculture
farmers, consumers, and policymakers. In recent years there has
been a backlash against perceived external
environmental effects of mainstream
agriculture, particularly regarding water pollution, resulting in
the organic movement
. One of the
major forces behind this movement has been the European Union
, which first certified
in 1991 and began reform
of its Common Agricultural
(CAP) in 2005 to phase out commodity-linked farm
subsidies, also known as decoupling
. The growth of organic farming
has renewed research in
alternative technologies such as integrated pest management
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. Food riots
taken place in many countries across the world. An epidemic
of stem rust
caused by race Ug99
is currently spreading across Africa and into Asia and is causing
major concern. Approximately 40% of the world's agricultural land
is seriously degraded. 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.
Since its development roughly 10,000 years ago, agriculture has
expanded vastly in geographical coverage and yields. Throughout
this expansion, new technologies and new crops were integrated.
Agricultural practices such as irrigation
, and pesticides
were developed long ago, but have made
great strides in the past century. The history of agriculture
has played a
major role in human history
agricultural progress has been a crucial factor in worldwide
-concentration and militaristic
specializations rarely seen in
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.
The Fertile Crescent
of Western Asia
, Egypt, and India were sites of
the earliest planned sowing and harvesting of plants that had
previously been gathered in the wild. Independent
development of agriculture occurred in northern and southern China,
Africa's Sahel, New Guinea and several regions of the Americas.
The eight so-called Neolithic founder crops
agriculture appear: first emmer wheat
and einkorn wheat
, then hulled
, bitter vetch
BC, small-scale agriculture reached Egypt.
least 7000 BC the Indian
subcontinent saw farming of wheat and barley, as attested by
archaeological excavation at Mehrgarh in Balochistan.
By 6000 BC,
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 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 that dwarfed all previous
expansions and continues today.
BC, the Sumerians had developed core
agricultural techniques including large-scale intensive cultivation
of land, mono-cropping, organized
irrigation, and the use of a specialized
labor force, particularly along the waterway now known as the
al-Arab, from its Persian Gulf delta to the confluence of the Tigris and Euphrates.
Domestication of wild aurochs
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
, and arrowroot
were first domesticated in the Americas
as far back as 5200 BC. The potato
, several varieties of bean
, and several other
plants were also developed in the New World, as was extensive
of steep hillsides
in much of Andean
South America. The Greeks
built on techniques pioneered
by the Sumerians but made few fundamentally new advances. Southern
Greeks struggled with very poor soils, yet managed to become a
dominant society for years. The Romans were noted for an emphasis
on the cultivation of crops for trade.
During the Middle Ages, farmers in North Africa, the Near East, and
Europe began making use of agricultural technologies including
irrigation systems based on hydraulic
principles, machines such as
, water-raising machines, dams,
and reservoirs. This combined with the invention of a three-field system
of crop rotation and
the moldboard plow
improved agricultural efficiency.
After 1492, a global exchange
previously local crops and livestock breeds occurred. Key crops
involved in this exchange included the tomato
the New World to the Old, and several varieties of wheat
, and sugar cane
going from the Old World to the New. The most important animal
exportation from the Old World to the New were those of the
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.
became an important staple crop in
northern Europe. Since being introduced by Portuguese in the 16th
have replaced traditional African crops as the
continent's most important staple food crops.
By the early 1800s, agricultural techniques, implements, seed
stocks and cultivated plants selected and given
a unique name because of its decorative or useful
had so improved that yield per land unit was
many times that seen in the Middle Ages. With the rapid rise of
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.
method for synthesizing
ammonium nitrate represented a major breakthrough and allowed
to overcome previous
constraints. In the past century agriculture has been characterized
by enhanced productivity, the substitution of labor for synthetic
fertilizers and pesticides, water
, and farm subsidies
recent years there has been a backlash against the external
environmental effects of conventional
agriculture, resulting in the organic
The cereals rice, corn, and wheat provide 60% of human food supply.
Between 1700 and 1980, "the total area of cultivated land worldwide
increased 466%" and yields increased dramatically, particularly
because of selectively-bred
high-yielding varieties, fertilizers, pesticides, irrigation, and
machinery. For example, irrigation increased corn yields
in eastern Colorado by 400 to
500% from 1940 to 1997.
However, concerns have been raised over the sustainability
of intensive agriculture.
Intensive agriculture has become associated with decreased soil
quality in India and Asia, and there has been increased concern
over the effects of fertilizers and pesticides on the environment,
particularly as population increases and food demand expands. The
monocultures typically used in intensive agriculture increase the
number of pests, which are controlled through pesticides. Integrated pest management
which "has been promoted for decades and has had some notable
successes" has not significantly affected the use of pesticides
because policies encourage the use of pesticides and IPM is
knowledge-intensive. Although the "Green Revolution" significantly
increased rice yields in Asia, yield increases have not occurred in
the past 15–20 years. The genetic "yield potential" has increased
for wheat, but the yield potential for rice has not increased since
1966, and the yield potential for maize has "barely increased in 35
years". It takes a decade or two for herbicide-resistant weeds to
emerge, and insects become resistant to insecticides within about a
decade. Crop rotation helps to prevent resistances.
Agricultural exploration expeditions, since the late nineteenth
century, have been mounted to find new species and new agricultural
practices in different areas of the world. Two early examples of
expeditions include Frank N. Meyer's fruit- and nut-collecting trip
to China and Japan from 1916-1918and the Dorsett-Morse Oriental
Agricultural Exploration Expedition to China, Japan, and Korea from
1929-1931 to collect soybean germplasm to support the rise in
soybean agriculture in the United States.
the agricultural output of
China was the largest in the world, accounting for almost
one-sixth of world share, followed by the EU, India and the USA,
according to the International Monetary Fund.
Economists measure the total factor productivity
agriculture and by this measure agriculture in the United States is
roughly 2.6 times more productive than it was in 1948.
Six countries - the US, Canada, France, Australia, Argentina and
Thailand - supply 90% of grain exports
, which are already
spurring heavy grain
imports in numerous
middle-sized countries, including Algeria, Iran, Egypt, and Mexico,
may soon do the same in larger countries, such as China or
Crop production systems
Cropping systems vary among farms depending on the available
resources and constraints; geography and climate of the farm;
government policy; economic, social and political pressures; and
the philosophy and culture of the farmer. Shifting cultivation
(or slash and burn
) is a system in which forests
are burnt, releasing nutrients to support cultivation of annual and
crops for a period of
several years. Then the plot is left fallow to regrow forest, and
the farmer moves to a new plot, returning after many more years
(10-20). This fallow period is shortened if population density
grows, requiring the input of nutrients (fertilizer
some manual pest control
cultivation is the next phase of intensity in which there is no
fallow period. This requires even greater nutrient and pest control
inputs. Further industrialization lead to the use of monocultures
, when one cultivar
is planted on a large acreage. Due to the
, nutrient use is
uniform, and pests tend to build up, necessitating the greater use
and fertilizers. Multiple
cropping, in which several crops are grown sequentially in one
year, and intercropping
, when several
crops are grown at the same time are other kinds of annual cropping
systems known as polycultures
environments, all of these
cropping systems are practiced. In subtropical
environments, the timing and extent of agriculture may be limited
by rainfall, either not allowing multiple annual crops in a year,
or requiring irrigation
. In all of these
environments perennial crops are grown (coffee
systems are practiced such as agroforestry
. In temperate
environments, where ecosystems were
, highly productive annual cropping is the
dominant farming system.
The last century has seen the intensification
relying upon new technologies of agricultural chemicals (fertilizers
, and plant breeding
the past few decades, a move towards sustainability
in agriculture has
also developed, integrating ideas of socio-economic justice and
conservation of resources and the environment within a farming
system. This has led to the development of many responses to the
conventional agriculture approach, including organic agriculture
, urban agriculture
, community supported
, ecological or biological agriculture, integrated farming
, and holistic management
Important categories of crops include grains and pseudograins,
pulses (legumes), forage, and fruits and vegetables. Specific crops
are cultivated in distinct growing
throughout the world. In millions of metric tons, based
Livestock production systems
, including horses
, and dogs
, are often used to help cultivate
other animals, and transport
farm products to buyers. Animal husbandry
not only refers to the
and raising of animals for meat or
to harvest animal products (like milk
, or wool
) on a continual
basis, but also to the breeding and care of species for work and
can be defined based on feed source, as grassland
- based, mixed, and landless. Grassland
based livestock production relies upon plant material such as
, and pastures
animals. Outside nutrient inputs
may be used, however manure is returned directly to the grassland
as a major nutrient source. This system is particularly important
in areas where crop production is not feasible due to climate or
soil, representing 30-40 million pastoralists. Mixed production
systems use grassland, fodder
crops and grain
feed crops as feed for ruminant and monogastic (one stomach; mainly
chickens and pigs) livestock. Manure is typically recycled in mixed
systems as a fertilizer for crops. Approximately 68% of all
agricultural land is permanent pastures used in the production of
livestock. Landless systems rely upon feed from outside the farm,
representing the de-linking of crop and livestock production found
more prevalently in OECD
member countries. In
the U.S., 70% of the grain grown is fed to animals on feedlots.
Synthetic fertilizers are more heavily relied upon for crop
production and manure utilization becomes a challenge as well as a
source for pollution.
Road leading across the farm allows
machinery access to the farm for production practices.
is the practice of
plowing soil to prepare for planting or for nutrient incorporation
or for pest control. Tillage varies in intensity from conventional
. It may improve
productivity by warming the soil, incorporating fertilizer and
controlling weeds, but also renders soil more prone to erosion,
triggers the decomposition of organic matter releasing
, and reduces the abundance and diversity of soil
the management of weeds
, and diseases
), mechanical (tillage
), and cultural practices are used. Cultural
practices include crop rotation
, avoidance, and resistance
attempts to use all of these methods to keep pest
populations below the number which would cause economic loss, and
recommends pesticides as a last resort.
includes both the source of nutrient inputs
for crop and livestock production, and the method of utilization of
produced by livestock. Nutrient inputs
can be chemical inorganic fertilizers
and mined minerals
. Crop nutrient use may also be managed
using cultural techniques such as crop
or a fallow
period. Manure is
used either by holding livestock where the feed crop is growing,
such as in managed
intensive rotational grazing
, or by spreading either dry or
liquid formulations of manure on cropland or pastures
is where rainfall is insufficient or variable, which occurs to some
degree in most regions of the world. Some farmers use irrigation
to supplement rainfall. In other areas such as
Plains in the U.S. and Canada, farmers use a fallow year to conserve soil moisture to use for
growing a crop in the following year.
70% of freshwater use worldwide.
Processing, distribution, and marketing
In the United States, food costs attributed to processing
, distribution, and marketing
have risen while the costs
attributed to farming have declined. From 1960 to 1980 the farm
share was around 40%, but by 1990 it had declined to 30% and by
1998, 22.2%. Market
has increased in the sector as well, with the top
20 food manufacturers accounting for half the food-processing value
in 1995, over double that produced in 1954. As of 2000 the top six
US supermarket groups had 50% of sales compared to 32% in 1992.
Although the total effect of the increased market concentration is
likely increased efficiency, the changes redistribute economic surplus
from producers (farmers)
and consumers, and may have negative implications for rural
Crop alteration and biotechnology
Crop alteration has been practiced by humankind for thousands of
years, since the beginning of civilization. Altering crops through
breeding practices changes the genetic make-up of a plant to
develop crops with more beneficial characteristics for humans, for
example, larger fruits or seeds, drought-tolerance, or resistance
to pests. Significant advances in plant breeding ensued after the
work of geneticist Gregor Mendel. His work on dominant and
recessive alleles gave plant breeders a better understanding of
genetics and brought great insights to the techniques utilized by
plant breeders. Crop breeding includes techniques such as plant
selection with desirable traits, self-pollination and
cross-pollination, and molecular techniques that genetically modify
the organism.Domestication of plants has, over the centuries
increased yield, improved disease
, 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
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 (maize) and barley.
The green revolution
the use of conventional hybridization
to increase yield many folds by creating "high-yielding varieties".
For example, average yields of corn (maize
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.
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.
Variations 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)..
(GMO) are organisms
material has been altered by genetic
engineering techniques generally known as recombinant DNA technology
Genetic engineering has expanded the genes available to breeders to
utilize in creating desired germlines for new crops. After
mechanical tomato-harvesters were developed in the early 1960s,
agricultural scientists genetically modified tomatoes to be more
resistant to mechanical handling. More recently, genetic
engineering is being employed in various parts of the world, to
create crops with other beneficial traits.
Herbicide-tolerant GMO Crops
seed has a herbicide resistant
gene implanted into its genome that allows the plants to tolerate
exposure to glyphosate
. Roundup is a
trade name for a glyphosate based product, which is a systemic,
non-selective herbicide used to kill weeds. Roundup-Ready seeds
allow the farmer to grow a crop that can be sprayed with glyphosate
to control weeds without harming the resistant crop.
Herbicide-tolerant crops are used by farmers worldwide. Today, 92%
of soybean acreage in the US is planted with genetically-modified
herbicide-tolerant plants. With the increasing use of
herbicide-tolerant crops, comes an increase in the use of
glyphosate based herbicide sprays. In some areas glyphosate
resistant weeds have developed, causing farmers to switch to other
herbicides. Some studies also link widespread glyphosate usage to
iron deficiencies in some crops, which is both a crop production
and a nutritional quality concern, with potential economic and
Insect-Resistant GMO Crops
Other GMO crops utilized by growers include insect-resistant crops,
which have a gene from the soil bacterium Bacillus thuringiensis
which produces a toxin specific to insects; insect-resistant crops
protect plants from damage by insects, one such crop is Starlink
. Another is cotton, which accounts
for 63% of US cotton acreage.
Some believe that similar or better pest-resistance traits can be
acquired through traditional breeding practices, and resistance to
various pests can be gained through hybridization or
cross-pollination with wild species. In some cases, wild species
are the primary source of resistance traits; some tomato cultivars
that have gained resistance to at least nineteen diseases did so
through crossing with wild populations of tomatoes.
Costs and Benefits of GMOs
Genetic engineers may someday develop transgenic plants
which would allow for
, sanitary engineering, and
maintaining or increasing yields while requiring fewer fossil fuel
derived inputs than conventional crops. Such developments would be
particularly important in areas which are normally arid and rely
upon constant irrigation, and on large scale farms.However, genetic
engineering of plants has proven to be controversial. Many issues
surrounding food security and environmental impacts have risen
regarding GMO practices. For example, GMOs are questioned by some
ecologists and economists concerned with GMO practices such as
, which is a
genetic modification that creates sterile seeds. Terminator seeds
are currently under strong international opposition and face
continual efforts of global bans.Another controversial issue is the
patent protection given to companies that develop new types of seed
using genetic engineering. Since companies have intellectual
ownership of their seeds, they have the power to dictate terms and
conditions of their patented product. Currently, ten seed companies
control over two-thirds of the global seed sales. Vandana Shiva
argues that these companies are
guilty of biopiracy
by patenting life and
exploiting organisms for profit Farmers using patented seed are
restricted from saving seed for subsequent plantings, which forces
farmers to buy new seed every year. Since seed saving is a
traditional practice for many farmers in both developing and
developed countries, GMO seeds legally bind farmers to change their
seed saving practices to buying new seed every year.
Locally adapted seeds are an essential hertitage that has the
potential to be lost with current hybridized crops and GMOs.
Locally adapted seeds, also called land races or crop eco-types,
are important because they have adapted over time to the specific
microclimates, soils, other environmental conditions, field
designs, and ethnic preference indigenous to the exact area of
cultivation. Introducing GMOs and hybridized commercial seed to an
area brings the risk of cross-pollination with local land races
Therefore, GMOs pose a threat to the sustainability of land races
and the ethnic heritage of cultures. Once seed contains transgenic
material, it becomes subject to the conditions of the seed company
that owns the patent of the transgenic material.
There is also concern that GMOs will cross-pollinate with wild
species and permanently alter native populations’ genetic
integrity; there are already identified populations of wild plants
with transgenic genes. GMO gene flow to related weed species is a
concern, as well as cross-pollination with non-transgenic crops.
Since many GMO crops are harvested for their seed, such as
rapeseed, seed spillage in is problematic for volunteer plants in
rotated fields, as well as seed-spillage during
Food safety and labeling
Food security issues also coincide with food
and food labeling
Currently a global treaty, the BioSafety Protocol, regulates the
trade of GMOs. The EU currently requires all GMO foods to be
labeled, whereas the US does not require transparent labeling of
GMO foods. Since there are still questions regarding the safety and
risks associated with GMO foods, some believe the public should
have the freedom to choose and know what they are eating and
require all GMO products to be labeled.
Agriculture imposes external costs
upon society through pesticides, nutrient runoff, excessive water
usage, and assorted other problems. A 2000 assessment of
agriculture in the UK determined total external costs
for 1996 of £2,343 million, or
£208 per hectare. A 2005 analysis of these costs in the USA
concluded that cropland imposes approximately $5 to 16 billion ($30
to $96 per hectare), while livestock production imposes $714
million. Both studies concluded that more should be done to
internalize external costs, and neither included subsidies in their
analysis, but noted that subsidies also influence the cost of
agriculture to society. Both focused on purely fiscal impacts. The
2000 review included reported pesticide poisonings but did not
include speculative chronic effects of pesticides, and the 2004
review relied on a 1992 estimate of the total impact of
A senior UN official and co-author of a UN report detailing this
problem, Henning Steinfeld, said "Livestock are one of the most
significant contributors to today's most serious environmental
problems". 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
. It produces 65% of human-related nitrous oxide
(which has 296 times the global warming potential of
) 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. Livestock expansion is cited as a key factor driving
deforestation, in the Amazon basin 70% of previously forested area
is now occupied by pastures and the remainder used for feedcrops.
Through deforestation and land degradation, livestock is also
driving reductions in biodiversity.
Land transformation and degradation
Land transformation, the use of land to yield goods and services,
is the most substantial way humans alter the Earth's ecosystems,
and is considered the driving force in the loss of biodiversity.
Estimates of the amount of land transformed by humans vary from
39–50%. Land degradation
long-term decline in ecosystem function and productivity, is
estimated to be occurring on 24% of land worldwide, with cropland
overrepresented. The UN-FAO report cites land management as the
driving factor behind degradation and reports that 1.5 billion
people rely upon the degrading land. Degradation can be deforestation
, soil erosion
, mineral depletion, or chemical
degradation (acidification and salinization
, excessive nutrients
in aquatic ecosystems resulting in algal blooms and anoxia, leads
to fish kills, loss of biodiversity, and renders water unfit for
drinking and other industrial uses. Excessive fertilization and
manure application to cropland, as well as high livestock stocking
densities cause nutrient (mainly nitrogen
from agricultural land.
These nutrients are major nonpoint pollutants
to eutrophication of aquatic ecosystems.
Pesticide use has increased since 1950 to 2.5 million tons annually
worldwide, yet crop loss due to pests has remained relatively
constant. The World Health Organization estimated in 1992 that 3
million pesticide poisonings occur annually, causing 220,000
deaths. Pesticides select for pesticide resistance
in the pest
population, leading to a condition termed the 'pesticide treadmill'
in which pest resistance warrants the development of a new
pesticide. An alternative argument is that the way to 'save the
environment' and prevent famine is by using pesticides and
intensive high yield farming, a view exemplified by a quote heading
the Center for Global Food Issues website: 'Growing more per acre
leaves more land for nature'. However, critics argue that a
trade-off between the environment and a need for food is not
inevitable, and that pesticides simply replace good agronomic
practices such as crop rotation.
has the potential to
affect agriculture through changes in temperature
(timing and quantity), CO2
, solar radiation
and the interaction of these
elements. Agriculture can both mitigate or worsen global warming
. Some of the increase in
in the atmosphere
comes from the decomposition
of organic matter
in the soil
, and much of the methane
emitted into the atmosphere is due to the decomposition of organic
matter in wet soils such as rice paddies
Further, wet or anaerobic
soils also lose nitrogen
, releasing the greenhouse gas nitric
. Changes in management can reduce the release of these
greenhouse gases, and soil can further be used to sequester
some of the
in the atmosphere.
Distortions in modern global agriculture
Differences in economic development, population density and culture
mean that the farmers of the world operate under very different
A US cotton farmer may receive US$230 in government subsidies per
acre planted (in 2003), while farmers in Mali and other third-world
countries do without. When prices decline, the heavily subsidised
US farmer is not forced to reduce his output, making it difficult
for cotton prices to rebound, but his Mali counterpart may go broke
in the meantime.
A livestock farmer in South Korea can calculate with a (highly
subsidized) sales price of US$1300 for a calf produced. A South
American Mercosur country rancher calculates with a calf's sales
price of US$120–200 (both 2008 figures).With the former, scarcity
and high cost of land is compensated with public subsidies, the
latter compensates absence of subsidies with economics of scale and
low cost of land.
In the Peoples Republic of China, a rural household's productive
asset may be one hectare of farmland.In Brazil, Paraguay and other
countries where local legislature allows such purchases,
international investors buy thousands of hectares of farmland or
raw land at prices of a few hundred US$ per hectare.
Agriculture and petroleum
Since the 1940s, agriculture has dramatically increased its
productivity, due largely to the use of petrochemical derived
, fertilizers, and increased
(the so-called Green Revolution
). Between 1950 and 1984,
as the Green Revolution transformed agriculture around the globe,
world grain production increased by 250%. This has allowed world population
to grow more than double
over the last 50 years. However, every energy unit delivered in
food grown using modern techniques requires over ten energy units
to produce and deliver, although this statistic is contested by
proponents of petroleum-based agriculture. 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
Modern or industrialized agriculture is dependent on petroleum in
two fundamental ways: 1) cultivation—to get the crop from seed to
harvest and 2) transport—to get the harvest from the farm to the
consumer's refrigerator. It takes approximately 400 gallons of oil
a year per citizen to fuel the tractors, combines and other
equipment used on farms for cultivation or 17 percent of the
nation's total energy use. Oil and natural gas are also the
building blocks of the fertilizers, pesticides and herbicides used
on farms. Petroleum is also providing the energy required to
process food before it reaches the market. It takes the energy
equivalent of a half-gallon of gasoline to produce a two-pound bag
of breakfast cereal. And that still does not count the energy
needed to transport that cereal to market; it is the transport of
processed foods and crops that consumes the most oil. The kiwi from
New Zealand, the asparagus from Argentina, the melons and broccoli
from Guatemala, the organic lettuce from California—most food items
on the consumer's plate travel average of 1,500 miles just to get
Oil shortages could interrupt this food supply. The consumer's
growing awareness of this vulnerability is one of several factors
fueling current interest in organic
and other sustainable farming
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. However, the reconditioning of soil to restore
nutrients lost during the use of monoculture
agriculture techniques made possible
by petroleum-based technology will take time.
The dependence on oil and vulnerability of the U.S. food supply has
also led to the creation of a conscious consumption movement in
which consumers count the "food miles" a food product has traveled.
The Leopold Center for Sustainable Agriculture defines a food mile
as: "...the distance food travels from where it is grown or raised
to where it is ultimately purchased by the consumer or end-user."
In a comparison of locally-grown food and long-distance food,
researchers at the Leopold Center found that local food traveled an
average of 44.6 miles to reach its destination compared with 1,546
miles for conventionally-grown and shipped food.
Consumers in the new local food movement who count food miles call
"; they advocate a
return to a locally-based food system where food comes from as
close as possible, whether or not it is organic. Locavores argue
that an organically-grown lettuce from California that is shipped
to New York is still an unsustainable food source because of
dependence on fossil fuels to ship it. In addition to the
"locavore" movement, concern over dependence on oil-based
agriculture has also dramatically increased interest in home and
Farmers have also begun raising crops such as corn (maize) for
non-food use in an effort to help mitigate peak oil
. This has
contributed 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.
One example of the chain reactions which could be caused by peak
oil issues involves the problems caused by farmers raising crops
such as corn (maize) for non-food use in an effort to help mitigate peak oil
. This has already
lowered food production. This food vs
issue will be exacerbated as demand for ethanol fuel
rises. Rising food and fuel costs has already limited the abilities
of some charitable donors to send food aid to starving populations.
In the UN, some warn that the recent 60% rise in wheat prices could
cause "serious social unrest in developing countries." In 2007,
higher incentives for farmers to grow non-food biofuel
crops combined with other factors (such as
over-development of former farm lands, rising transportation costs,
, growing consumer
demand in China and India, and population growth
) to cause food shortages
in Asia, the Middle East,
Africa, and Mexico, as well as rising food
prices around the globe. As of December 2007, 37 countries faced
food crises, and 20 had imposed some sort of food-price controls.
Some of these shortages resulted in food riots
and even deadly
Another major petroleum issue in agriculture is the effect of
petroleum supplies will have on fertilizer production. By far the
biggest fossil fuel input to agriculture is the use of natural gas
as a hydrogen source for the Haber-Bosch
Natural gas is used because it is the cheapest currently available
source of hydrogen. When oil production becomes so scarce that
natural gas is used as a partial stopgap replacement, and hydrogen
use in transportation increases, natural gas will become much more expensive
. If the Haber
Process is unable to be commercialized using renewable energy (such
as by electrolysis
) or if other sources
of hydrogen are not available to replace the Haber Process, in
amounts sufficient to supply transportation and agricultural needs,
this major source of fertilizer would either become extremely
expensive or unavailable. This would either cause food shortages or
dramatic rises in food prices.
Mitigation of effects of petroleum shortages
One effect oil shortages could have on agriculture is a full return
to organic agriculture
. In light
of peak oil concerns, organic methods are much more sustainable
than contemporary practices because they use no petroleum-based
pesticides, herbicides, or fertilizers. Some farmers using modern
organic-farming methods have reported yields as high as those
available from conventional farming. Organic farming may however be
-intensive and would
require a shift of work force from urban to rural areas.
It has been suggested that rural communities might obtain fuel from
process, which uses agricultural
to provide charcoal fertilizer, some fuel
food, instead of the normal food vs fuel
debate. As the synfuel would be
used on site, the process would be more efficient and may just
provide enough fuel for a new organic-agriculture fusion.
It has been suggested that some transgenic plants
may some day
be developed which would allow for maintaining or increasing yields
while requiring fewer fossil fuel derived inputs than conventional
crops. The possibility of success of these programs is questioned
by ecologists and economists concerned with unsustainable GMO
practices such as terminator seeds
and a January 2008 report shows that GMO practices "fail to deliver
environmental,social and economic benefits." While there has been
some research on sustainability using GMO crops, at least one hyped
and prominent multi-year attempt by Monsanto Company
has been unsuccessful,
though during the same period traditional breeding techniques
yielded a more sustainable variety of the same crop. 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.Nonetheless, some governments in Africa continue to
view investments in new transgenic technologies as an essential
component of efforts to improve sustainability.
the goals and methods of agricultural production. At the policy
level, common goals of agriculture include:
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