Agriculture refers to the production
of food and goods through farming and
forestry. Agriculture was the key
development that led to the rise of civilization, with the husbandry of domesticated animals
and plants (i.e. crops)
creating food surpluses that enabled the
development of more densely
populated and stratified societies. The study of
agriculture is known as agricultural
science (the related practice of gardening is studied in horticulture). Agriculture encompasses a wide variety of
specialties and techniques, including ways to expand the lands suitable for
plant raising, by digging water-channels and other forms of irrigation.
Cultivation of crops on arable
land and the pastoral herding of livestock on rangeland 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 (e.g. permaculture or organic
agriculture) and intensive farming (e.g. industrial agriculture). Modern agronomy, plant breeding, pesticides and fertilizers, 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 and modern practices in animal husbandry such as intensive pig farming (and similar
practices applied to the chicken) have similarly increased
the output of meat, but have raised concerns
about animal cruelty and the health effects of the antibiotics, growth hormones, and other
chemicals commonly used in industrial meat production. The major agricultural products can be
broadly grouped into foods, fibers,
fuels, raw materials, pharmaceuticals and stimulants, and an assortment of
ornamental or exotic products. In the 2000s, plants have been used to grow
biofuels, biopharmaceuticals, bioplastics,[1] and
pharmaceuticals.[2] Specific foods
include cereals, vegetables, fruits,
and meat. Fibers
include cotton, wool,
hemp, silk and flax.
Raw
materials include lumber and bamboo. Stimulants
include tobacco, alcohol,
opium, cocaine,and digitalis. Other useful materials
are produced by plants, such as resins. Biofuels include methane from biomass, ethanol,
and biodiesel. Cut flowers, nursery
plants, tropical fish and birds for the pet trade
are some of the ornamental products. In 2007, about one third of the world's
workers were employed in agriculture. However, the relative significance of
farming has dropped steadily since the beginning of industrialization, and in 2003 –
for the first time in history – the services sector overtook agriculture as the economic sector employing the most
people worldwide.[3] Despite the fact
that agriculture employs over one-third of the world's population, agricultural
production accounts for less than five percent of the gross world product (an aggregate
of all gross domestic
products