Agriculture
Agriculture, also
called farming or husbandry, is the cultivation of animals, plants, fungi, and other life forms for food, fiber, and biofuel, medicinal and other
products used to sustain and enhance human life. Agriculture was the key
development in the rise of sedentary human civilization, whereby farming of domesticated species created food
surpluses that nurtured the development of civilization. The study of
agriculture is known as agriculture science. The history of agriculture dates
back thousands of years, and its development has been driven and defined by
greatly different climates, cultures, and technologies. However, all farming
generally relies on techniques to expand and maintain the lands that are
suitable for raising domesticated species. For plants, this usually requires
some form of irrigation, although
there are methods of dry land farming.
Livestock are raised in a combination of grassland based and landless
systems, in an industry that covers almost one third of the world ice and water
free area. In the developed world, industrial agriculture based on large scale monoculture has become
the dominant system of modern farming, although there is growing support for sustainable
agriculture, including permaculture and organic agriculture.
Until the Industrial Revolution, the vast majority of the
human population labored in agriculture. Pre industrial agriculture was
typically subsistence agriculture self sufficiency in which farmers raised most
of their crops for their own consumption instead of cash crops for trade. A
remarkable shift in agricultural practices has occurred over the past century
in response to new technologies, and the development of world markets. This
also has led to technological improvements in agricultural techniques, such as
the Haber Bosch method for
synthesizing ammonium nitrate which
made the traditional practice of recycling nutrients with crop rotation and
animal manure less important.
Modern agronomy, plant breeding,
agrochemicals such a as pesticides and fertilizers, and technological improvements have
sharply increased yields from cultivation, but at the same time have caused
widespread ecological damage and negative human health effects. Selective
breeding and modern practices in animal husbandry have similarly increased the
output of meat, but have raised concerns about animal welfare and the health effects of the antibiotics,
growth hormones, and other chemicals commonly used in industrial meat
production. Genetically is an
increasing component
of agriculture, although they are banned in several countries. Agricultural
food production and water management are increasingly becoming global issues
that are fostering debate on a number of fronts. Significant degradation of
land and water resources, including the depletion of aquifers, has been observed in recent decades, and the effects of
global warming on agriculture and of agriculture on global warming are still
not fully understood.
The major agricultural products can be broadly grouped into
foods, fibers, fuels, and raw materials. Specific
foods include cereals, vegetables, fruits, oils, meats and spices. Fibers
include cotton, wool, hemp, silk, and flax. Raw materials include lumber and
bamboo. Other useful materials are produced by plants, such as resins, dyes,
drugs, perfumes, biofuels and ornamental products such as cut flowers and
nursery plants. Over one third of the world's workers are employed in
agriculture, second only to the services sector, although the percentages of
agricultural workers in developed countries has decreased significantly over
the past several centuries.
Etymology and terminology
The
word agriculture is a late Middle English adaptation of
Latin agricultūra, from ager, field, and cultura, cultivation or growing Agriculture
usually refers to human activities, although it is also observed in certain
species of ant, termite and ambrosia beetle. To practice agriculture means to
use natural resources to produce commodities which maintain life, including
food, fibber, forest products, horticultural crops, and their related services.
This definition includes arable faming or agronomy, and horticulture, all terms for the growing of plants, animal
husbandry and forestry. A
distinction is sometimes made between forestry and agriculture, based on the
former's longer management rotations, extensive versus intensive management
practices and development mainly by nature, rather than by man. Even then, it
is acknowledged that there is a large amount of knowledge transfer and overlap
between silviculture and agriculture. In traditional farming, the two are often
combined even on small landholdings, leading to the term agroforestry.
Prehistoric Origins
Forest gardening, a plant based
food production system, is thought to be the world oldest agroecosystem. Forest
gardens originated in prehistoric times along jungle clad river banks and in
the wet foothills of monsoon regions. In the gradual process of a family
improving their immediate environment, useful tree and vine species were
identified, protected and improved whilst undesirable species were eliminated.
Eventually superior foreign species were selected and incorporated into the
family's garden.
Neolithic
The Fertile Crescent of
Western Asia first saw the domestication of animals, starting the Neolithic
Revolution. Between 10,000 and 13,000 years ago, the ancestors of modern
cattle, sheep, goats and pigs were domesticated in this area. The gradual
transition from wild harvesting to deliberate cultivation happened
independently in several areas around the globe. Agriculture allowed for the
support of an increased population, leading to larger societies and eventually
the development of cities. It also created the need for greater organization of
political power as
decisions had to be made regarding labor and harvest allocation and access
rights to water and land. Agriculture bred immobility, as populations settled
down for long periods of time, which led to the accumulation of material goods.
Early Neolithic villages
show evidence
of the ability to process grain, and the Near East is the ancient home of the
ancestors of wheat, barley and peas. There is evidence of the cultivation of
figs in the Jordan valley as long as 11,300 years ago, and cereal production in
Syria approximately 9,000 years ago. During the same period, farmers in China
began to farm rice and millet, using man-made floods and fires as part of their
cultivation regimen. Fiber crops were domesticated as early as food crops, with
China domesticating hemp, cotton being developed independently in Africa and
South America, and the Near East domesticating flax. The use of soil
amendments, including manure, fish, compost and ashes, appears to have begun
early, and developed independently in several areas of the world, including
Mesopotamia, the Nile Valley and Eastern Asia.
Squash was grown in Mexico nearly 10,000 years ago,
while mazie like plants, derived from the wild teosinte, began to be seen at
around 9,000 years ago. The derivation of teosinte into modern corn was slow,
however, and it took until 5,500 to 6,000 years ago to turn into what we know today as maize.
It then gradually spread across North America and was the major crop of Native
Americans at the time of European exploration. Beans were domesticated around the same time,
and together these three plants formed the three sisters nutritional foundation
of many native populations in North and Central America. Combined with peppers,
these crops provided a balanced diet for much of the continent. Grapes were first grown for wine approximately 8,000 years ago, in the southern
Caucasus, and by 3000
BC had spread to the Fertile Crescent, the Jordan Valley and Egypt.
Agriculture advanced to Europe slightly
later, reaching the northeast of the continent from the east around 4000 BC.
The idea that agriculture spread to Europe, rather than independently
developing there, has led to two main hypotheses. The first is a wave of
advance, which holds that agriculture traveled slowly and steadily across the
continent, while the second, population pulse theory, holds that it moved in
jumps. Also around
6000 years ago, horses first began to be domesticated in the Eurasian steppes.
Initially used for food, it was quickly discovered that they were useful for
field work and carrying goods and people. Around 5,000 years ago, sunflowers
were first cultivated
in North America, while South America Andes region was developing the potato.
A minor center of
domestication, the indigenous peoples of the eastern United States appear to
have domesticated numerous crops, including tobacco.
Bronze and Iron
Ages
Beginning around 3000 BC, nomadic
Pastoralism, with societies focused on the care of livestock for subsistence,
appeared independently in several areas in Europe and Asia. The main region was
the steppes stretching from the Hungarian plain to Manchuria, where cattle,
sheep, horses, and to a lesser extent yaks and Bactrian camels provided sustenance. The second was in
Arabia, where one humped camels were the main animal, with sheep, goats and
horses also seen. The third area was a band of societies in areas of eastern
and central Africa with a tropical savannah climate. Cattle and goats were found most often in
this area, with smaller numbers of sheep, horses and camels. A fourth area,
more minor than the others, was found in northern Europe and Asia and was
focused on reindeer herding.
Between 2500 and 2000 BC, the simplest
form of the plough, called the arid, spread throughout Europe, replacing the hoe. This change in
equipment significantly increased cultivation ability, and affected the demand
for land, as well as ideas about property, inheritance and family rights.
Before this period, simple digging sticks or hoes were used. These tools would have
also been easier to transport, which was a benefit as people only stayed until
the soil's nutrients were depleted. However, as the continuous cultivating of
smaller pieces of land became a sustaining practice throughout the world, ards
were much more efficient than digging sticks. As humanity became more
stationary, empires, such as the new kingdom of Egypt and the Ancient romans,
arose dependent upon agriculture to feed their growing populations, and slavery,
which was used to provide the labor needed for continually intensifying
agricultural processes. Agricultural technology continued to improve, allowing
the expansion of available crop varieties, including a wide range of fruits,
vegetables, oil crops, spices and other products. China was also an important
center for agricultural technology development during this period. During the
Zhou dynasty, the first canals were built, and irrigation was used extensively.
The later three kingdoms and northern and southern dynasties brought the first biological pest control,
extensive writings on agricultural topics and technological innovations such as
steel and the wheelbarrow.
In the ancient world, fresh products, such
as meats, dairy products and fresh fruits and vegetables, were likely consumed
relatively close to where they were produced. Less perishable products, such as
grains, preserved foods, olive oil and wine, were often traded over an
extensive network of land and sea routes. The ancient trade in agricultural
goods was well established, with wine traded in the Mediterranean region in the
6th century BC and Rome receiving extensive shipments of grain as tax payments
by the 2nd century BC. Huge amounts of grain were transported, mainly by sea,
and it was during this period that the subsidization of grain farming began,
for the prevention of famine. Ancient Rome was a major center for agricultural
trade. Trade routes stretched from Britain and Scandinavia in the west to India
and China in the east, and included major crops, such as grain, wine and olive
oil, as well as additional products, including spices, fabrics and drugs.
In ancient Greece and Rome, many scholars
documented farming techniques, including the use of fertilizers. Much of what
was believed about farming and plant nutrition at this time was later found to
be incorrect, but their theories provided the scientific foundation for the
development of agricultural theories through the Middle ages. Ideas about soil fertility and
fertilization remained much the same from the time of Greco-Roman scholars
until the 19th century, with correspondingly low crop yields. By the time of
Alexander the Great conquests, the role of horses had developed, and they
played a huge role in warfare and agriculture. Innovations continued to be
developed which allowed them to work longer, harder and more efficiently. By
medieval times they became the primary source of power for agriculture,
transport and warfare, a position they held until the development of the steam
and internal combustion engines. The Mayan culture developed several
innovations in agriculture during its peak, which ranged from 400 BC to 900 AD
and was heavily dependent upon agriculture to support its population. The
Mayans used extensive canal and raised field systems to farm the large portions
of swampland on the Yucatan Peninsula.
Middle Ages
The Middle Ages saw significant
improvements in the agricultural techniques and technology. During this time
period, monasteries spread throughout Europe and became important centers for
the collection of knowledge related to agriculture and forestry. The manorial
systems, which existed
under different names throughout Europe and Asia, allowed large landowners
significant control over both their land and its laborers, in the form of
peasants or serfs. During the medieval period, the Arab world was critical in
the exchange of crops and technology between the European, Asia and African
continents. Besides transporting numerous crops, they introduced the concept of
summer irrigation to Europe and developed the beginnings of the plantation
system of sugarcane growing through the use of slaves for intensive
cultivation. Population continued to increase along with land use. From 100 BC
to 1600 AD, methane emissions, produced by domesticated animals and rice growing
increased substantially.
Global Exchange
After 1492, a global
exchange of previously local crops and livestock breeds occurred. Key crops
involved in this exchange included maize, potatoes, sweet potatoes and manioc
travelling from
the New World to the Old, and several varieties of wheat, barley, rice and turnips
going from the old World to the New. There were very few livestock species in
the New World, with horses, cattle, sheep and goats being completely unknown
before their arrival with Old World settlers. Crops moving in both directions
across the Atlantic Ocean caused population growth around the world, and had a lasting effect
on many cultures. Since being introduced by Portuguese in the 16th century,
maize and manioc have replaced traditional African crops as the continent's
most important staple food crops.
After its introduction from South America
to Spain in the late 1500s, the potato became an important staple crop
throughout Europe by the late 1700s. The potato allowed farmers to produce more
food, and initially added variety to the European diet. The nutrition boost
caused by increased potato consumption resulted in lower disease rates, higher
birth rates and lower mortality rates, causing a population boom throughout the
British Empire, the US and Europe. The introduction of the potato also brought
about the first intensive use of fertilizer, in the form of guano imported to
Europe from Peru, and the first artificial pesticide, in the form of arsenic compound used to fight Colorado potato beetles. Before the adoption of the potato as a
major crop, the dependence on grain caused repetitive regional and national famines
when the crops failed:
17 major famines in England alone between 1523 and 1623. Although initially
almost eliminating the danger of famine, the resulting dependence on the potato
eventually caused the European potato failure, a disastrous crop failure from
disease resulting in widespread famine, and the death of over one million
people in Ireland alone.
Modern Developments
The British Agricultural Revolution, with
its massive increases in agricultural productivity and net output, is a topic
of ongoing debate among historians and agricultural scholars. The changes in
agriculture in Britain between the 16th and 19th centuries would subsequently
affect agriculture around the world. Major points of development included
enclosure, mechanization, crop retation and selective breeding. Prior to the
1960s, historians viewed the British Agricultural Revolution of having been largely
facilitated by a small number of key innovators, including Robert bakewell,
Thomas coke and Charles Townshend. However, modern historians disperse much of
the importance surrounding these individual men, and instead point to them
holding a smaller position within a major societal shift regarding agriculture
in Britain.
The agricultural changes, along with
industrialization and migration, allowed the population of Britain, as well as
other countries who followed its model, such as the US, Germany and Belgium, to
escape from the Malthusian trap and increase both their population and their standard
of living. It is
estimated that the productivity of wheat in England went up from about 19
bushels per acre in 1720 to 21–22 bushels by the middle of the century and
finally stabilized at around 30 bushels by 1840.
Premodern agriculture across Europe was
characterized by the feudal open field system, where farmers worked on strips
of land in fields that were held in common; this was inefficient and reduced
the incentive to improve productivity. Many farms began to be enclosed by yeomen
who improved the use of their land. This process of land reform
accelerated in the
18th century with special acts of parliament to expedite the legal process. The
consolidation of large, privately owned holdings encouraged the improvement of productivity
through experimentation by enterprising landowners. By the 1750s, the market
for agriculture was substantially commercialized - crop surpluses were
routinely sold by the producers on the market or exported elsewhere.
These social changes were coupled with
technical improvements. New methods of crop rotation and land use resulted in
large additions to the amount of arable land. The four field crop
rotation was
popularized by Charles Townshend in the 18th century. The system
opened up a fodder crop and grazing crop allowing livestock to be bred year
round. Yields of cereal crops increased as farmers utilized nitrogen
rich manure and nitrogen fixing crops such as clover, increasing the available nitrogen in the
soil and removing the limiting factor on cereal productions that had existed
prior to the early 19th century. This improved production per farmer led to an
increase in population and in the available workforce, creating the labor force
needed for the industrial revolution.
The development of agriculture into its
modern form was made possible through a continuing process of mechanization.
Prior to this, basic
agricultural tools had slowly been improved over centuries of use. The plough,
for example, was a heavy implement with wheels in the 1500s. By the 1600s it
was lighter, and by 1730, the Rotherham plough dramatically changed farming
with no wheels, interchangeable parts, stronger construction and less weight.
During the early 1800s, cast iron replaced wood for many parts, leading to longer-lasting
implements. Seed drills had been under development since the early 1500s, but
it was Jethro Tull 1731 invention of a horse-drawn seed drill and horse hoe that would eventually revolutionize planting
in Britain, although they would not become popular until the early 1800s.
Andrew Meikle patented the first practical threshing machine in 1784.
The industrial revolution caused a boom in
international trade and shipping. Increased production caused a rise in the
need for raw materials, with European merchants purchasing the majority of the
goods. The value of goods traded worldwide increased by five times between 1750
and 1914, with annual shipping tonnages increasing from 4 million to 30 million
tons between 1800 and 1900. In the second half of the 19th century, trade also
expanded in the food and wool markets, and England began to trade quantities of industrial
products for wheat from around the world. The vast expansion of railroads that
followed the invention of the steam engine further revolutionized world trade, especially in
the Americas and East Asia, as goods could now be more easily traded across
vast land distances. The developments of heat
processing and refrigeration in the 19th century led to a similar revolution in the
meat industry, as they allowed meat to be shipped long distances without
spoiling. Countries in tropical locations, such as Australia and South America,
were at the forefront of this effort.
In the mid 1800s, horse drawn machinery,
such as the Mccormick reaper, revolutionized harvesting, while inventions such
as the cotton gin made possible the processing of large amounts of crops.
During this same period, farmers began to use steam powered threshers and
tractors, although they were found to be expensive, dangerous and a fire
hazard. The first gasoline powered tractors were successfully developed around
1900, and in 1923, the international Harvester Farmall tractor became the first
all-purpose tractor, and marked a major point in the replacement of draft
animals with machines. Since that time, self-propelled mechanical harvesters,
planters, translators and other equipment have been developed, further
revolutionizing agriculture. These inventions allowed farming tasks to be done
with a speed and on a scale previously impossible, leading modern farms to
output much greater volumes of high-quality produce per land unit.
The scientific investigation of
fertilization began at the Rothamsted experiment station in 1843 by John Bennet
Lawes. He developed the first commercial process for fertilizer production the obtaining of phosphate
from the
dissolution of coprolites in sulphuric acid. In 1909 the revolutionary Haber Bosch method to synthesize ammonium nitrate was first
demonstrated; it represented a major breakthrough and allowed crop yields
to overcome previous
constraints. In the years after World War II, the use of synthetic fertilizer
increased rapidly, in sync with the increasing world population.
Contemporary agriculture
In the past century agriculture has been
characterized by increased productivity, the substitution of synthetic
fertilizers and pesticides for labor, water pollution, and farm subsidies. In
recent years there has been a backlash against the external environment effects
of conventional
agriculture, resulting in the organic and sustainable agriculture
movements. 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 in 2005 to
phase out commodity linked farm subsidies, also known as decoupling. 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 and selective breeding. Recent mainstream
technological developments include genetically modified food.
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, climate change, growing consumer demand in China and India, and population
growth, caused 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 smallholder
agriculture may be part of the solution to concerns about food prices and
overall food security. They in part base this on the experience of Vietnam,
which went from a food importer to large food exporter and saw a significant
drop in poverty, due mainly to the development of smallholder agriculture in
the country.
Disease and land
degradation are two of the major concerns in agriculture today. For example, an
epidemic of stem rust on wheat caused by the lineage is currently spreading across Africa and
into Asia and is causing major concerns due to crop losses of 70% or more under
some conditions. Approximately 40% of the world 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 Ghana based
Institute for Natural Resources in Africa.
In 2009, the
agriculture output of china was the largest in the world, followed by the
European Union, India and the United States, according to the international
monetary fund. Economists measure the total factor productivity of agriculture and by this measure
agriculture in the United States is roughly 1.7 times more productive than it
was in 1948. Six countries the US, Canada, France, Australia, Argentina and
Thailand supply 90% of gain exports. Water deficits, 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 India.
Workforce
As of 2011, the
international labour organization states that approximately one billion people,
or over 1/3 of the available work force, are employed in the global
agricultural sector. Agriculture constitutes approximately 70% of the global
employment of children, and in many countries employs the largest percentage of
women of any industry. The service sector only overtook the agricultural sector
as the largest global employer in 2007. Between 1997 and 2007, the percentage
of people employed in agriculture fell by over four percentage points, a trend
that is expected to continue. The number of people employed in agriculture varies
widely on a per-country basis, ranging from less than 2% in countries like the
US and Canada to over 80% in many African nations. In developed countries, these figures are
significantly lower than in previous centuries. During the 16th century in Europe,
for example, between 55 and 75 percent of the population was engaged in
agriculture, depending on the country. By the 19th century in Europe, this had
dropped to between 35 and 65 percent. In the same countries today, the figure is less than 10%.
Safety
Agriculture remains a hazardous industry
and farmers worldwide remain at high risk of work related injuries, lung
disease, noise-induced hearing loss, skin diseases, as well as certain cancers
related to chemical use and prolonged sun exposure. On industrialized farms, injuries frequently involve the use of agricultural
machinery, and a
common cause of fatal agricultural injuries in developed countries is tractor
rollovers. Pesticides and other chemicals used in farming can also be hazardous
to worker health, and workers exposed to pesticides may experience illness or
have children with birth defects. As an industry in which families commonly share in work and
live on the farm itself, entire families can be at risk for injuries, illness,
and death. Common causes of fatal injuries among young farm workers include
drowning, machinery and motor vehicle related accidents.
The International
Labour Organization considers agriculture one of the most hazardous of all
economic sectors. It estimates that the annual work related death toll among
agricultural employees is at least 170,000, twice the average rate of other
jobs. In addition, incidences of death, injury and illness related to
agricultural activities often go unreported. The organization has developed the safety
and health in agriculture convention, which covers the range of risks in the agriculture
occupation, the prevention of these risks and the role that individuals and
organizations engaged in agriculture should play.
Agricultural production systems
Crop cultivation 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 is
a system in which forests are burnt, releasing nutrients to support cultivation
of annual and then perennial 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. This fallow period is shortened if population density
grows, requiring the input of nutrients and some manual pest control. Annual
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 led to the use
of monocultures, when one cultivar is planted on a large acreage. Because of
the low biodiversity, nutrient use is uniform and pests tend to build up, necessitating the
greater use of pesticides 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
In subtropical and arid 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 and systems are practiced such as
agroforestry. In temperate environments, where ecosystems were predominantly
grassland or prairie, highly productive annual cropping is the dominant farming
system.
Important categories of crops include cereals
and pseudocereals, pulses, forage, and fruits and vegetables. Specific crops
are cultivated in distinct growing regions throughout the world. In millions of metric tons,
based on FAO estimate.
Livestock production systems
Animals, including horses, mules, oxen,
water buffalo, camels, llamas, alpacas, donkeys, and dogs, are often used to
help cultivate fields, harvest crops, wrangle other animals, and transport farm
products to buyers. Animals husbandry not only refers to the breeding and
raising of animals for meat or to harvest animal products on a continual basis,
but also to the breeding and care of species for work and companionship.
Livestock production systems can be
defined based on feed source, as grassland based, mixed, and landless. As of
2010, 30% of Earth ice and water free area was used for producing livestock,
with the sector employing approximately 1.3 billion people. Between the 1960s
and the 2000s, there was a significant increase in livestock production, both
by numbers and by carcass weight, especially among beef, pigs and chickens, the
latter of which had production increased by almost a factor of 10. Non meat
animals, such as milk cows and egg producing chickens, also showed significant
production increases. Global cattle, sheep and goat populations are expected to
continue to increase sharply through 2050. Aquaculture or fish farming, the
production of fish for human consumption in confined operations, is one of the
fastest growing sectors of food production, growing at an average of 9% a year
between 1975 and 2007.
During the second half of the 20th
century, producers using selective breeding focused on creating livestock
breeds and crossbreeds that increased production, while mostly disregarding the
need to preserve genetic diversity. This trend has led to a significant
decrease in genetic diversity and resources among livestock breeds, leading to
a corresponding decrease in disease resistance and local adaptations previously
found among traditional breeds.
Grassland based livestock production relies
upon plant material such as shrubland, rangeland, and pastures for feeding ruminant 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 because of climate or soil,
representing 30–40 million pastoralists. Mixed production systems use
grassland, fodder crops and grain feed crops as feed for ruminant and
monogastric livestock.
Manure is typically recycled in mixed systems as a fertilizer for crops.
Landless systems rely upon feed from
outside the farm, representing the delinking of crop and livestock production
found more prevalently in organisation for Economic co operation and
development member countries. Synthetic fertilizers are more heavily relied
upon for crop production and manure utilization becomes a challenge as well as
a source for pollution. Industrialized countries use these operations to
produce much of the global supplies of poultry and pork. Scientists estimate
that 75% of the growth in livestock production between 2003 and 2030 will be in
confined animal feeding operations, sometimes called factory farming. Much of
this growth is happening in developing countries in Asia, with much smaller amounts
of growth in Africa. Some of the practices used in commercial livestock
production, including the usage of growth hormones, are controversial.
Production practices
Tillage is the practice of plowing soil to
prepare for planting or for nutrient incorporation or for pest control. Tillage
varies in intensity from conventional to no
till. 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 CO2, and reduces the abundance and
diversity of soil organisms
Pest control includes the management of weeds, insects, mites, and
diseases. Chemical, biological, mechanical, and cultural practices are used. Cultural practices
include crop rotation, culling, cover crops, intercropping, composting, avoidance, and resistance.. Integrated
pest management 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.
Nutrient management
includes both the source of nutrient inputs for crop and livestock production,
and the method of utilization of manure produced by livestock. Nutrient inputs
can be chemical inorganic fertilizers, manure, green manure, compost and mined
minerals. Crop nutrient use may also be managed using cultural techniques such
as crop rotation or a fallow period. Manure is used either by holding livestock
where the feed crop is growing, such as in managed intensive rotational gazing,
or by spreading either dry or liquid formulations of manure on cropland or pastures.
Water
management is needed 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 the Great 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. Agriculture represents 70% of freshwater use worldwide.
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 makeup 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, although initially largely ignored for
almost 50 years, gave plant breeders a better understanding of genetics and
breeding techniques. 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 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 selection and breeding in the 1920s and 1930s improved
pasture in New Zealand.
The Green Revolution
popularized the use of conventional hybridization to sharply increase yield by
creating high yielding varieties. For example, average yields of corn in the
USA have increased from around 2.5 tons per hectare in 1900 to about 9.4 in
2001. Similarly, worldwide average wheat yields have increased from less than 1
in 1900 to more than 2.5 in 1990. South American average wheat yields are
around 2, African under 1, and 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. Variations in yields are due mainly to variation in climate, genetics,
and the level of intensive farming techniques.
Genetic engineering
Genetically modified organisms are
organisms whose genetic 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
gremlins for new crops. Increased durability, nutritional content, insect and
virus resistance and herbicide tolerance are a few of the attributes bred into
crops through genetic engineering. For some, GMO crops cause food safety and
food labelling concerns. Numerous countries have placed restrictions on the
production, import and or use of GMO foods and crops, which have been put in
place due to concerns over potential health issues, declining agricultural
diversity and contamination of non GMO crops. Currently a global treaty, the Biosafety
Protocol, regulates the trade of GMOs. There is ongoing discussion regarding
the labelling of foods made from GMOs, and while the EU currently requires all
GMO foods to be labelled, the US does not.
Herbicide resistant seed has a gene implanted into its
genome that allows the plants to tolerate exposure to herbicides, including
glyphosates. These seeds allow the farmer to grow a crop that can be
sprayed with herbicides to control weeds without harming the resistant crop.
Herbicide tolerant crops are used by farmers worldwide. 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 health implications.
Other GMO crops used by growers include insect-resistant
crops, which have a gene from the soil bacterium Bacillus thuringiensis, which
produces a toxin specific to insects. These crops protect plants from damage by
insects. 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 19
diseases did so through crossing with wild populations of tomatoes.
Environmental impact
Agriculture imposes external
costs upon society
through pesticides, nutrient runoff, excessive water usage, loss of natural
environment 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, while livestock production imposes $714
million. Both studies, which focused solely on the fiscal impacts, concluded
that more should be done to internalize external costs. Neither included
subsidies in their analysis, but they noted that subsidies also influence the
cost of agriculture to society. The study found that agriculture and food consumption are two
of the most important drivers of environmental pressures, particularly habitat
change, climate change, water use and toxic emissions.
Livestock
issues
A senior UN official and co-author of a UN
report detailing this problem, Henning Seinfeld, said Livestock are one of the
most significant contributors to today 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 CO2. It produces 65% of human related nitrous and 37% of all human-induced It also generates 64% of the ammonia emission. 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 feed crops. Through deforestation and
land degradation, livestock is also driving reductions in biodiversity.
Land and water issue
Land transformation, the use of land to
yield goods and services, is the most substantial way humans alter the Earth
ecosystems, and is considered the driving force in the loss of biodiversity.
Estimates of the amount of land transformed by humans vary from 39 to 50% Land degradation,
the 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, desertification, soil erosion, mineral depletion, or chemical degradation.
Eutrophication, 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 runoff and leaching rom agricultural land.
These nutrients are major nonpoint
pollutants contributing to eutrophication of aquatic ecosystems.
Agriculture
accounts for 70% of withdrawals of freshwater resources. Agriculture is a major
draw on water from aquifers, and currently draws from these underground water
sources at an unsustainable rate. It is long known that aquifers in areas as
diverse as northern China, the upper
ganes and the western US are being depleted, and new research
extends these problems to aquifers in Iran, Mexico and Saudi Arabia. Increasing
pressure is being placed on water resources by industry and urban areas,
meaning that water scarcity is increasing and agriculture is facing the
challenge of producing more food for the world's growing population with fewer
water resources. Agricultural water usage can also cause major environmental
problems, including the destruction of natural wetlands, the spread of water borne
diseases, and land degradation through Stalinization and water logging, when
irrigation is performed incorrectly.
Pesticides
Pesticide use has
increased since 1950 to 2.5 million tons annually worldwide, yet crop loss from
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.
Climate
Change
.
Climate change has the potential to affect agriculture
through changes in temperature, rainfall, CO2, solar radiation and
the interaction of these elements. Extreme events, such as droughts and floods,
are forecast to increase as climate change takes hold. Agriculture is among
sectors most vulnerable to the impacts of climate change, water supply for
example, will be critical to sustain agricultural production and provide the
increase in food output required to sustain the world's growing population.
Fluctuations in the flow of rivers are likely to increase in the twenty first
century. Based on the experience of countries in the Nile river basin and other
developing countries, depletion of water resources during seasons crucial for
agriculture can lead to a decline in yield by up to 50%. Transformational approaches will be needed
to manage natural resources in the future. For example, policies, practices and
tools promoting climate smart agriculture will be important, as will better use
of scientific information on climate for assessing risks and vulnerability.
Planners and policy makers will need to help create suitable policies that
encourage funding for such agricultural transformation.
Agriculture can both mitigate and worsen
global warming. Some of the increase in CO2 in the atmosphere comes from the
decomposition of organic matter in the soil, and much of the methane emitted
into the atmosphere is caused by the decomposition of organic matter in wet
soils such as rice paddies, as well as the normal digestive activities of farm
animals. Further, wet or anaerobic soils also lose nitrogen through
denitrification, releasing the greenhouse gases nitric oxide and nitrous oxide. Changes
in management can reduce the release of these greenhouse gases, and soil can
further be used to sequester some of the CO2 in the atmosphere.
There are several factors within the field
of agriculture that contribute to the large amount of CO2 emissions. The
diversity of the sources ranges from the production of farming tools to the
transport of harvested produce. Approximately 8% of the national carbon
footprint is due to agricultural sources. Of that, 75% is of the carbon
emissions released from the production of crop assisting chemicals. Factories
producing insecticides, herbicides, fungicides, and fertilizers are a major
culprit of the greenhouse gas. Productivity on the farm itself and the use of
machinery is another source of the carbon emission. Almost all the industrial
machines used in modern farming are powered by fossil fuels. These instruments
are burning fossil fuels from the beginning of the process to the end. Tractors
are the root of this source. The tractor is going to burn fuel and release CO2
just to run. The amount of emissions from the machinery increase with the
attachment of different units and need for more power. During the soil
preparation stage tillers and plows will be used to disrupt the soil. During
growth watering pumps and sprayers are used to keep the crops hydrated. And
when the crops are ready for picking forage or combine harvester is used. These
types of machinery all require additional energy which leads to increased
carbon dioxide emissions from the basic tractors. The final major contribution
to CO2 emissions in agriculture is in the final transport of produce. Local
farming suffered a decline over the past century due to large amounts of farm
subsidies. The majority of crops are shipped hundreds of miles to various
processing plants before ending up in the grocery store. These shipments are
made using fossil fuel burning modes of transportation. Inevitably this
transport adds to carbon dioxide emissions.
Agricultural economics
Agricultural economics
refers to economics as it relates to the production, distribution and
consumption of goods and services combining agricultural production with
general theories of marketing and business as a discipline of study began in
the late 1800s, and grew significantly through the 20th century. Although the
study of agricultural economics is relatively recent, major trends in agriculture
have significantly affected national and international economies throughout
history, ranging from tenant farmers and sharecropping in the post American
Civil War southern United States to the European feudal systems of manorialism.
In the United States, and elsewhere, food costs attributed to food
processing, distribution,
and agricultural marketing, sometimes referred to as the value chain,
have risen while the
costs attributed to farming have declined. This is related to the greater
efficiency of farming, combined with the increased level of value addition
provided by the supply chain. Market concentrations has increased in the sector as well, and
although the total effect of the increased market concentration is likely
increased efficiency, the changes redistribute economic surplus from producers
and consumers, and may have negative implications for rural communities.
National government
policies can significantly change the economic marketplace for agricultural
products, in the form of taxation, subsidies, tariffs and other measures. Since at least the 1960s,
a combination of import/export restrictions, exchange
rate policies and
subsidies has affected farmers in both the developing and developed world. In the
1980s, it was clear that non subsidized farmers in developing countries were
experiencing adverse affects from national policies that created artificially
low global prices for farm products. Between the mid 1980s and the early 2000s,
several international agreements were put into place that limited agricultural
tariffs, subsidies and other trade restrictions.
However, as of 2009, there was still a
significant amount of policy driven distortion in global agricultural product
prices. The three agricultural products with the greatest amount of trade
distortion were sugar, milk and rice, mainly due to taxation. Among the
oilseeds, sesame had the greatest amount of taxation, but overall, feed grains
and oilseeds had much lower levels of taxation than livestock products. Since
the 1980s, policy driven distortions have seen a greater decrease among
livestock products than crops during the worldwide reforms in agricultural
policy. Despite this progress, certain crops, such as cotton, still see
subsidies in developed countries artificially deflating global prices, causing
hardship in developing countries with non subsidized farmers. Unprocessed
commodities are
generally graded to indicate quality. The quality affects the price the
producer receives. Commodities are generally reported by production quantities, such as volume, number or
weight.
Energy and agriculture
Since the 1940s,
agricultural productivity has increased dramatically, due largely to the
increased use of energy intensive mechanization, fertilizers and pesticides.
The vast majority of this energy input comes from fossil fuel sources. Between
the 1960–65 measuring cycle and the cycle from 1986 to 1990, the Green
revolution transformed agriculture around the globe, with world grain
production increasing significantly between 70% and 390% for wheat and 60% to
150% for rice, depending on geographic area as doubled. Modern agriculture heavy reliance on and mechanization has raised concerns that
oil shortages could increase costs and reduce agricultural output, causing food
shortages.
Modern or industrialized agriculture is
dependent on fossil fuels in two fundamental ways direct consumption on the
farm and indirect consumption to manufacture inputs used on the farm. Direct
consumption includes the use of lubricants and fuels to operate farm vehicles
and machinery, and use of gasoline, liquid propane, and electricity to power dryers, pumps,
lights, heaters, and coolers. American farms directly consumed about 1.2
exajoules in 2002, or just over 1% of the nation total energy.
Indirect consumption is mainly oil and
natural gas used to manufacture fertilizers and pesticides, which accounted for
0.6 exajoules. The natural gas and coal consumed by the production of nitrogen fertilizer
can account for
over half of the agricultural energy usage. China utilizes mostly coal in the
production of nitrogen fertilizer, while most of Europe uses large amounts of
natural gas and small amounts of coal. According to a 2010 report published by
the royal society, agriculture is increasingly dependent on the direct and
indirect input of fossil fuels. Overall, the fuels used in agriculture vary
based on several factors, including crop, production system and location. He
energy used to manufacture farm machinery is also a form of indirect
agricultural energy consumption. Together, direct and indirect consumption by
US farms accounts for about 2% of the nation energy use. Direct and indirect
energy consumption by U.S. farms peaked in 1979, and has gradually declined
over the past 30 years. Food systems encompass not just agricultural
production, but also off farm processing, packaging, transporting, marketing,
consumption, and disposal of food and food related items. Agriculture accounts
for less than one fifth of food system energy use in the US.
Mitigation
of effects of petroleum shortages
In the event of a petroleum shortage,
organic agriculture can be more attractive than conventional practices that use
petroleum-based pesticides, herbicides, or fertilizers. Some studies using
modern organic farming methods have reported yields as high as those available
from conventional farming. In the aftermath of the fall
of the Soviet Union, with
shortages of conventional petroleum based inputs, Cuba made use of mostly
organic practices, including biopesticides, plant-based pesticides and
sustainable cropping practices, to feed its populace. However, organic farming
may be more labor intensive and would require a shift of the workforce from
urban to rural areas. The reconditioning of soil to restore nutrients lost during
the use of monoculture agriculture techniques also takes time.
It has been suggested that rural
communities might obtain fuel from the biochar and sinful process, hitch uses agricultural waste to provide charcoal fertilizer, some fuel and food, instead of the normal debate. As the sinful would be used on site,
the process would be more efficient and might just provide enough fuel for a
new organic agriculture fusion.
