Agriculture includes both subsistence agriculture , whichis producing enough food to meet the needs of the farmer and family (but no more), and also (almost universally in the "developed" nations and increasingly so inother areas) the production of financial income from cultivation of the land or commercial raising of animals ( animal husbandry ). Agriculture is the practice -- thestudy of these disciplines is called agriculturalscience .
Increasingly, besides food for humans and animal feeds , agriculture produces goodssuch as cut flowers, ornamental and nursery plants, fertilizers , animalhides , leather , industrial chemicals ( starch , ethanol , and plastics ), fibers ( cotton , wool , hemp , and flax ), fuels ( methane , biodiesel , biomass ), and both legal and illegal drugs ( biopharmaceuticals , tobacco , marijuana , opium , cocaine ). Geneticallyengineered plants and animals produce specialty drugs.
In the Western world, use of improved genetics , better management of soilnutrients, and improved weed control have greatly increased yields per unitarea. At the same time, use of mechanization has decreased labor requirements, releasing most of the populace from intenseagricultural labor. The developing world is behind by Western measures of productivity, because of unavailability of theeducation, capital and technology base needed to sustainthese advances, and usually ecoregion with less optimal climates and soils .
Modern agriculture depends heavily on engineering and technology and on the biological and physical sciences. Irrigation , drainage , conservation , and sanitary engineering—each of which is important insuccessful farming—are some of the fields requiring the specialized knowledge of agricultural engineers.
Agricultural chemistry deals with other vital farming concerns, such as the application of fertilizer, insecticides (see Pest control ), and fungicides, soil makeup, analysis of agriculturalproducts, and nutritional needs of farm animals.
Plant breeding and genetics contribute immeasurably to farmproductivity. Genetics has also made a science of livestock breeding. Hydroponics, a method of soilless gardening in which plantsare grown in chemical nutrient solutions, may help meet the need for greater food production as the world's populationincreases.
The packing, processing, and marketing of agricultural products are closely related activities also influenced by science.Methods of quick-freezing and dehydration have increased the markets for farm products (see FoodProcessing and Preservation ; Meat PackingIndustry ).
Mechanization, the outstanding characteristic of late 19th- and 20th-century agriculture, has eased much of the backbreakingtoil of the farmer. More significantly, mechanization has enormously increased farm efficiency and productivity (see AgriculturalMachinery ). Animals including horses, oxen, llamas, alpacas, and dogs, however, are still used to cultivate fields, harvestcrops, and transport farm products to markets in many parts of the world.
Airplanes and helicopters are used in agriculture for seeding, spraying operations for insect and disease control,transporting perishable products, and fighting forest fires. Radio and television disseminate vital weather reports and otherinformation such as market reports that concern farmers. Computers have become an essential tool for farm management.
Animal husbandry means breeding and raising animals for meat or to harvest animal products (like milk, eggs, or wool) on acontinual basis.
In recent years, some aspects of industrial intensiveagriculture have been the subject of increasing discussion. The widening sphere of influence held by large seed and chemicalcompanies and meat packers has been a source of concern both within the farming community and for the general public. The patentprotection given to companies that develop new types of seed using genetic engineering has allowed seed to be licensed to farmers inmuch the same way that computer software is licensed to users. This has changed the balance of power in favor of the seedcompanies, allowing them to dictate terms and conditions previously unheard of. Some argue these companies are guilty of biopiracy .
Increasing consumer awareness of agricultural issues has led to the rise of community-supported agriculture , local food movement , slow food , and commercial organic farming , though these yet remain fledgling industries.
Determining the origin of agriculture is problematic since it pre-dates the invention of writing . Some authorities insist localized farming took place more than 10,000 years ago, while others believe theearliest systematic plantings/harvestings took place no more than 7,000 years ago. The practice of agriculture is often used todistinguish the neolithic period from earlier parts of the stone age . The first crops that humans domesticated included wheat ( einkorn and emmer ) and barley . It is clear that farming was invented at least twice, probably more often: oncein the Fertile Crescent (some say by the Natufian culture , others say by the Sumerians ), once in East Asia (rice), and once in CentralAmerica (maize, squash). Most likely, there was a gradual transition from a hunter-gatherer economy to an agricultural one, via a lengthy period when some crops were deliberatelyplanted, and other foods were gathered from the wild. The reasons for the earliest introduction of farming may have included climate change. Farming allows a much greater density of population than can besupported by hunting and gathering, and the ability of farmers to feed large numbers of people whose activities have nothing todo with material production was the crucial factor in the rise of standing armies.
After 1492 , the world's agricultural patterns were shuffled in the widespread exchangeof plants and animals known as the Columbian Exchange . Cropsand animals that were previously only known in the Old World were now transplanted in the New, and vice versa.
Agricultural policy focuses on the goals and methods ofagricultural production. At the policy level, common goals of agriculture include:
World production of major crops in 2002
In millions of metric tons, based on USDA estimates:
Domestication of plants is done in order to increase yield, disease resistance, drought tolerance, ease of harvest, and toimprove the taste and nutritional value and many other characteristics. Centuriesof careful selection and breeding have had enormous effects on the characteristics of crop plants. Plant breeders use greenhousesand other techniques to get as many as three generations of plants per year, so that they can make improvements all the morequickly. Extensive radiation mutagenesis efforts (i.e. primitive genetic engineering) during the 1950s produced the modern commercial varieties of grains such as wheat, corn and barley.
For example, average yields of corn ( maize ) in the USA have increased from around 2.5tons per hectare (40 bushels per acre) in 1900 to about 9.4 t/ha (150 bushels per acre) in 2001 , primarily due to improvements in genetics. Similarly, worldwide average wheat yieldshave increased from less than 1 t/ha in 1900 to more than 2.5 t/ha in 1990 . South American average wheat yields are around 2t/ha, African under 1 t/ha, Egypt and Arabia upto 3.5 to 4 t/ha with irrigation. In contrast, the average wheat yield in countries such as France is over 8 t/ha. Higher yields are due to improvements in genetics, as well as use of intensive farmingtechniques (use of fertilizers, chemical pest control , growth control toavoid lodging).
[Conversion note: 1 bushel (q) of wheat = 60 pounds (lb) ≈ 27.215 kg. 1 bushel of corn = 56 pounds ≈ 25.401kg]
Very recently, genetic engineering has begun to beemployed in some parts of the world to speed up the selection and breeding process. The most widely used modification is aherbicide resistance gene that allows plants to tolerate exposure to glyphosate. A less frequently used but more controversialmodification causes the plant to produce a toxin to reduce damage from insects (c.f. Starlink ).
There are specialty producers who raise less common types of livestock or plants.
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