agriculture

Crop dusting: spraying crops with insecticide and pesticide from an aeroplane. Spraying the crops in this way allows a large area to be sprayed quickly and also avoids having to drive vehicles through fields, thus potentially damaging the crops.

Calendar for October, from an 11th-century English manuscript. Farm workers are gathering in the hay crop with scythes and pitchforks.

Before the agrarian revolution, land was farmed in strips separated by ditches and livestock was grazed on common land.

Queen Elizabeth the Queen Mother visiting the Royal Cornwall Show. This annual event, held at Wadebridge, is among the largest livestock shows in the UK. In 2000, 113,000 people attended the show over three days. As well as livestock, there are also separate horse and dog shows, a flower show, and marquees showcasing Cornish produce.

Potatoes planted early, in March or April, can be ready for harvesting by late June. Commercially-grown potatoes are mechanically harvested. The same machine digs the potatoes out of the ground, cleans them of most of the dirt, then carries them by means of conveyor chains up to a grading table, where they are cleaned and sorted by hand before being loaded into a truck.

Small fields and small holdings are typical of farming in the west of Ireland. The dry-stone walls are easily breached when the farmer needs to let his livestock roam from one field to another.

Fields in southern Mexico. Agriculture accounts for about one tenth of Mexico's gross domestic product (GDP). The country produces crops for both subsistence and local consumption, and for export. Crops include maize, squash, coffee, and cotton, as well as speciality crops such as henequen, used for its fibre, and maguey, from which tequila is derived.

Rice harvesting, Nepal. Agricultural smallholdings provide the livelihood of over 80% of the population. The introduction of small-scale mechanization and improved agricultural practices in recent years has helped to lessen the burden on farmers and their families.

Mountain village, Costa Rica. The country's economy is based largely on agriculture, and around 49% of the population lives in rural areas.

Terraces in Nepal. Creating terraces allows for the transformation of steep slopes and hillsides into usable farmland. Some 85% of Nepalese live in rural areas and depend on agriculture for income.

A pattern of agricultural land use. The large town or city represents the market. Land close to the centre will be more expensive and require more intensive farming. Market gardening and dairying need to be close to the market to be profitable, while arable and livestock farms can be placed at a greater distance. A farmer may choose what to produce on the basis of how far the farm is from the market.

The practice of farming, including the cultivation of the soil (for raising crops) and the raising of domesticated animals. The units for managing agricultural production vary from smallholdings and individually owned farms to corporate-run farms and collective farms run by entire communities or by the government.

Crops are cultivated for human or animal food, or as industrial crops such as cotton and sisal. For successful production, the land must be prepared (ploughed, cultivated, harrowed, and rolled), seed must be planted and the growing plants nurtured. This may involve fertilizers, irrigation, pest control by chemicals, and monitoring of acidity or nutrients. When the crop has grown, it must be harvested and, depending on the crop, processed in a variety of ways before it is stored or sold. Greenhouses allow cultivation of plants in cold climates. Hydroponics allows commercial cultivation of crops using nutrient-enriched water instead of soil. Special methods, such as terracing, may be adopted to allow cultivation in steep regions and to retain topsoil in mountainous areas with heavy rainfall.

Animals are raised for wool, milk, leather, dung (as fuel), or meat. They may be semidomesticated, such as reindeer, or fully domesticated but nomadic (where naturally growing or cultivated food supplies are sparse), or kept on a farm. Animal farming involves rearing, feeding, breeding, gathering the produce (eggs, milk, or wool), slaughtering, and further processing such as tanning.

History

Prehistoric times Agriculture developed in the Middle East and Egypt at least 10,000 years ago, when people discovered the possibilities of growing crops and domesticating animals. They gave up being wandering hunter-gatherers, and adopted a more settled life. Farming communities soon became the base for society in China, India, Europe, Mexico, and Peru. Farming then spread throughout the world. Neolithic farmers lived in village communities, sometimes built on stilts over lakes; they knew how to spin, weave, and make pots; they kept domesticated dogs, horses, oxen, sheep, goats, and pigs; crops included wheat, barley, and beans. Milk residues on Iron Age pottery found in Northamptonshire were dated in 1998 as being 2,300 years old. Similar residues have been dated from 4000 BC, providing early evidence of dairy farming in Britain.

Medieval agriculture These prehistoric beginnings ultimately led to the evolution of the village open-field system, which became the basis of medieval agriculture prevalent in England during Saxon times and for long afterwards. The houses of the villagers clustered together in the centre of an area consisting partly of pasture, but to a larger extent of arable land, usually divided into three fields: one under grain, a second under peas, beans, or grain, and the third fallow (without a crop) and in a state of preparation for receiving one in its turn.

The agrarian revolution Reorganization along more scientific and productive lines took place in Europe in the 18th century with improved crop rotation. The 18th century saw what came to be called the agrarian revolution. To a degree, production was increased because of technical improvements - new crops, crop rotations, selective breeding, new buildings, and drainage, the use of manure, and new implements. In England, it was associated also with a re-organization of land-holding (enclosure) and the adoption of a capitalist business ethic. The large-scale cultivation of turnips and other root crops from the 18th century made it possible to feed cattle through the winter, whereas they had previously had to be slaughtered and the meat preserved by salting.

The introduction of potatoes, red clover, and turnips in the 17th century had marked a considerable advance, and the ‘three-field’ system was gradually replaced by the Norfolk, or four-course, crop rotation. The 18th century witnessed improvements in farm animals through the work of such pioneers as Robert Bakewell, who improved the quality of horned stock and sheep, by means of selective breeding.

The 19th century Following a period of depression after the Napoleonic Wars, a period of rapid development occurred in 19th-century British agriculture. After the work of Justus von Leibniz on chemical nutrients in the soil, crops were improved by means of artificial fertilizers (dung and waste materials had been the only kinds of fertilizer previously employed). Bones came first, though Humphry Davy also mentioned phosphate of lime, sulphate of potash, and salts of magnesium. Nitrate of soda and guano were first imported 1830; superphosphate began to be used on a large scale in the early 1840s; potash manures came later, and were followed by the discovery of basic slag.

The improvement of wheat by crossing was begun towards the end of the 18th century. Practically all kinds of crop plants were improved on similar lines. Reaping machines and other devices for harvesting and after-treatment of crops were developed, and different forms of power employed for working many of them.

During the 19th century advances were also made in the knowledge and treatment of plant diseases, especially those due to parasites. The rapid development in biological appliances (especially microscopes) and techniques not only placed the study of fungi on a scientific footing, but also enabled the science of bacteriology to be created, largely as a result of the pioneer work of Pasteur. Bacteria were found not only to be agents of infectious disease, but also to play an important part in the chemical changes occurring in the soil and in dairy processes.

Equally valuable progress was also made in respect of livestock. Many breeds were improved or established on Bakewell's lines, and the formation of numerous breed societies in the latter part of the century secured the maintenance of high standards. Biological advances led to improvement in the treatment of animal diseases, while at the same time the importance of farm hygiene came to be realized. Concentrated foods, of which linseed cake was the first (1795), gradually came to play an important part in winter feeding and the promotion of early maturity.

The 20th century Agriculture continued to make considerable advances during the 20th century. After World War II, there was an explosive growth in the use of agricultural chemicals: weedkillers, insecticides, fungicides, and fertilizers. In the 1960s there was development of high-yielding species, especially in the green revolution of the developing world, and industrialized countries began intensive farming of cattle, poultry, and pigs. In the 1980s, hybridization by genetic engineering methods and pest control by the use of chemicals plus pheromones were developed. However, there was also a reaction against some forms of intensive agriculture because of the pollution and habitat destruction caused. One result of this was a growth of alternative methods, including organic farming.

Organic farming From the 1970s there has been a movement towards more sophisticated natural methods without chemical sprays and fertilizers. These methods are desirable because nitrates from fertilizers have been seeping into the ground water, insecticides are found in lethal concentrations at the top of the food chain, some weedkillers are associated with human birth defects, and hormones fed to animals to promote fast growth have damaging effects on humans.

Overproduction The greater efficiency in agriculture achieved since the 19th century, coupled with post-World War II government subsidies for domestic production in the USA and the European Union (EU), have led to the development of high stocks, nicknamed ‘lakes’ (wine, milk) and ‘mountains’ (butter, beef, grain). There is no simple solution to this problem, as any large-scale dumping onto the market undermines local products. Increasing concern about the starving and the cost of storage has led the USA and the EU to develop measures for limiting production, such as letting arable land lie fallow to reduce grain crops. The USA had some success at selling surplus wheat to the USSR when the Soviet crop was poor, but the overall cost of bulk transport and the potential destabilization of other economies has acted against high producers exporting their excess on a regular basis to needy countries. Intensive farming methods also contribute to soil erosion and water pollution.

Agriculture in developing countries Except for the oil- or mineral-rich countries, agriculture is the principal industry of the developing world. The export of primary products such as chocolate, hides, vegetable oils, fibres, tea, and coffee provide the principal source of revenue and fluctuations in yield and market price make economic planning difficult. In general the possible agricultural technology is sufficient; the limits to development are often economic, social, and political. Where agriculture is the principal employment of a people and there is little alternative employment, development must exclude any reduction in the workforce, so that mechanization is not always helpful. Fertilizer supply and distribution are important, and better-yielding varieties of cereals able to respond to fertilizers and with increased disease resistance have been the key to the green revolution in agricultural production.