Agriculture, science, and industry of managing the growth of plants and animals for human use. In a broad sense, agriculture includes cultivation of the soil (soil management), growing and harvesting of crops (crop farming), breeding and raising of livestock (animal husbandry), dairy farming, forestry, and poultry farming.
Regional and national agriculture are covered in more detail in individual country and continent articles.
II MODERN AGRICULTURE
Modern agriculture is characterized by relatively high levels of inputs, often produced off-farm, and high levels of outputs. Standard farm management practice is to divide these inputs into those that vary directly with the output (variable inputs) and those that do not (fixed inputs). Fixed inputs include agricultural machinery, and modern agriculture is dependent on the manufacture of machinery for cultivations, harvesting, and other farm operations. Machinery is also needed for draining soils (see Drainage) and, in drier climates, irrigating crops (see Irrigation).
Mechanization has been one of the main characteristics of 20th-century agriculture, easing much of the back-breaking toil of the farmer. Developments in machinery, along with advances in plant breeding and animal breeding, have helped to increase agricultural productivity: it is now possible to produce more output per unit of inputs, fixed and variable. In Western countries, there has also been a trend towards larger, more powerful machinery at the expense of full-time labour. For this type of machinery to be economic, large fields and farms are needed and the substitution of machinery for labour is one reason why farm size has increased in Western countries. The high ratio of machinery to labour inputs in modern agriculture has two further consequences. First, it is intensive in its requirements for energy, and is, therefore, reliant on stable supplies of fuel; second, it is relatively capital intensive; thus a properly functioning financial system is also a requirement for the success of modern agriculture.
The variable inputs include seeds, fertilizers, and crop protection products (herbicides, pesticides, and fungicides), and feed and veterinary treatments for livestock production. Advances in crop and animal science have led to a much better match between crop and animal needs for variable inputs, resulting in less waste. For example, the timing and level of nitrogen fertilizer applied to crops can be closely matched to the crop’s needs; this means that the farmer can apply less fertilizer, cut his costs of production, and reduce losses of nitrogen to the environment.
Plant breeding and, more recently, genetic modification of crops such as soya and cotton, contribute substantially to farm productivity. Improved understanding of genetics has also placed livestock breeding on a more scientific basis. Despite these improvements, yields for winter wheat, one of the world’s major food crops, have increased by less than in previous decades. Over the period 1984-2004, for example, yields increased from 7.7 to 7.8 tonnes per hectare (19 to 19.3 tonnes per acre) in the United Kingdom and from 2.6 to 2.9 tonnes per hectare (6.4 to 7.2 tonnes per acre) in the United States. In Asia, yield increases have been more pronounced: wheat yields in India have caught up with the United States, increasing from 1.8 to 2.7 tonnes per hectare (4.5 to 6.7 tonnes per acre) over the same period.
Modern agriculture is usually linked to an advanced food processing and marketing sector, although the two can be quite distinct, with most of the activities that transform agricultural products into what people want to eat—the value added—taking place beyond the farm gate. Methods of processing, freezing, chilling, and preserving have changed the nature of the foods that people eat, allowing produce to be stored for long periods of time. Food processing, in developed countries, is now a large-scale industry.
Organic farming methods are becoming more widely practised in developing countries as a reaction to recent food scares generated by bovine spongiform encephalopathy (BSE) and concerns over pesticide residues and the intensive nature of modern farming. In Austria, for example, some 13 per cent of farmland is organic; in the United Kingdom, it is nearer 4 per cent.
III WORLD AGRICULTURE
Over the 10,000-year period, since agriculture was first developed, people have discovered the food value of wild plants and animals and have domesticated and bred them. The most important are cereals, such as wheat, rice, barley, corn, and rye; sugar cane and sugar beet; animals that are used for meat, such as sheep, cattle, goats, and pigs; poultry, such as chickens, ducks, and turkeys; and such products as milk, cheese, eggs, nuts, and oils. Fruits, vegetables, and olives are also major food sources for human beings. Feed grains for animals include soya beans, field corn, and sorghum. Separate articles on individual plants, including grasses and silage (fodder), and animals contain further information.
Agricultural income is also derived from non-food crops such as rubber, fibre plants, tobacco, and oilseeds used in synthetic chemical compounds, as well as from the raising of animals for their pelts.
The conditions that determine what will be raised include climate, ecology, water supply, and terrain. Problems over extensive deforestation for agriculture in developing countries have intensified in recent decades. Tropical deforestation increased rapidly after 1950, helped by the increased availability of heavy machinery. Historically, as it developed over the centuries in temperate regions, agriculture has depended upon forest removal; for example, most of England’s woodlands were deforested by 1350.
The proportion of people working in agriculture has fallen, from 52 per cent of the world’s labour force in 1990 to 43 per cent in 2004. The distribution in 2004 ranged from 55 per cent of the total labour force in Africa to about 1.8 per cent in the United Kingdom. In Asia, the figure was 54 per cent; in Latin America, 18 per cent; in Europe, 8 per cent; and in North America, 2 per cent. While agriculture has an important contribution to make to economic growth, particularly during the early stages of a country’s development, economic growth inevitably leads to a decline in the contribution of agriculture to the economy and as a source of employment.
Farm size varies widely from region to region. For example, in the early 2000s, the average for Canadian farms was about 273 hectares (675 acres) per farm, while the average size of a single landholding in Asia was somewhat less than 1 hectare (2.47 acres). The major part of production often comes from the largest farms: for example, in the United Kingdom, just over half of food production comes from the largest 10 per cent of farms.
Size also depends on the purpose of the farm. Commercial farming, or production for cash, is usually on large holdings. The latifundia of Latin America are large, privately owned estates worked by tenant labour. Single-crop plantations produce tea, rubber, and cocoa. Wheat farms are most efficient when they comprise some thousands of hectares and can be worked by teams of people and machines. Australian sheep stations and other livestock farms must be large to provide grazing for thousands of animals. The agricultural plots of Chinese communes and the cooperative farms held by Peruvian communities are other necessarily large agricultural units, as were the collective farms that were owned and operated by state employees in the former USSR.
Individual subsistence farms or small-family mixed-farm operations (see Smallholding) are decreasing in number in developed countries but are still numerous in the developing countries of Africa and Asia. Nomadic herders range over large areas in sub-Saharan Africa, Afghanistan, and Lapland; and herding is a major part of agriculture in such areas as Mongolia. A counter-trend in developed countries is the increase in part-time farming, where farmers, often on small farms, gain a substantial part of their income in other occupations.
The importance of an individual country as an exporter of agricultural products depends on many variables. Among them is the possibility that the country is inadequately developed on an industrial level to produce processed goods in sufficient quantity or technical sophistication. Such agricultural exporters include Ghana, with cocoa, and Myanmar (formerly Burma), with rice. On the other hand, an exceptionally well-developed country may produce surpluses that are not needed by its own population; this is the case with the United States, Canada, and the European Union (EU); these surpluses may be encouraged by the operation of agricultural policies, such as the EU’s Common Agricultural Policy.
Because nations depend on agriculture for food, raw materials, and its contribution to national income, trade in agriculture is a constant international concern. It is regulated by international agreements, overseen by the World Trade Organization (WTO). Trading groups such as the EU have agricultural policies that restrict trade, to the advantage of their own farmers, but to the disadvantage of agricultural exporting nations, many of which are developing countries. One of the main aims of the WTO is to liberalize trade in agricultural commodities.
The history of agriculture may be divided into four broad periods of unequal length, differing widely in date according to the region: prehistoric; historic through the Roman period; feudal, and scientific.
A Prehistoric Agriculture
Early agriculturists were, it is agreed, largely of Neolithic culture. Sites occupied by such people are located in south-western Asia, in what are now Iran, Iraq, Israel, Jordan, Syria, and Turkey; in south-eastern Asia, in what is now Thailand; in Africa, along the River Nile in Egypt; and in Europe, along the River Danube and in Macedonia, Thrace, and Thessaly. Early centres of agriculture have also been identified in the Huang (Yellow River) area of China; the Indus River valley of India and Pakistan; and the Tehuacán Valley of Mexico, north-west of the Isthmus of Tehuantepec.
The dates of domesticated plants and animals vary with the regions, but most pre-date the 6th-millennium bc, and the earliest may date from 10,000 bc. Scientists have used dating methods (carbon-14 testing) on animal and plant remains and have dated finds of domesticated sheep that existed as long ago as 9000 bc in northern Iraq; cattle (the 6th millennium bc in north-eastern Iran); goats (8000 bc in central Iran); pigs (8000 bc in Thailand and 7000 bc in Thessaly); onagers, or asses, (7000 bc in Jarmo, Iraq); and horses (4350 bc in Ukraine). The llama and alpaca were domesticated in the Andean regions of South America by the mid-3rd-millennium bc.
According to carbon dating, wheat and barley were domesticated in the Middle East in the 8th-millennium bc; millet and rice in China and south-eastern Asia by 5500 bc; and squash in Mexico by about 8000 bc. Legumes found in Thessaly and Macedonia are dated as early as 6000 bc. Flax was grown and apparently woven into textiles early in the Neolithic period.
The farmer began, most probably, by noting which wild plants were edible or otherwise useful and learned to save the seed and to replant it in cleared land. Long cultivation of the most prolific and hardiest plants yielded a stable strain. Herds of goats and sheep were perhaps assembled from captured young wild animals, and those with the most useful traits—such as small horns and high milk yield—were bred. The aurochs seems to have been the ancestors of European cattle, and an Asian wild ox of the zebu, the humped cattle of Asia. The chicken was domesticated very early. The transition from hunting and food-gathering to a dependence on food production was gradual, and in a few isolated parts of the world has not yet been accomplished. Crops and domestic meat supplies were augmented by fish and wildfowl as well as by the meat of wild animals.
The Neolithic farmers lived in simple dwellings—in caves and in small houses of sun-baked mud brick or of reed and wood. These homes were grouped into small villages or existed as single farmsteads surrounded by fields, sheltering animals and human beings in adjacent or joined buildings. In the Neolithic period, the growth of cities such as Jericho (founded c. 9000 bc) was stimulated by the production of surplus crops.
Pastoralism may have been a later development. Evidence indicates that mixed farming, combining cultivation of crops and stock raising, was the most common Neolithic pattern. Nomadic herders, however, roamed the steppes of Europe and Asia, where the horse and camel were domesticated.
The earliest tools of the farmer were made of wood and stone. They included the stone adze; the sickle or reaping knife with sharpened stone blades, used to gather grain; the digging stick, used to plant seeds, and, with later adaptations, as a spade or hoe; and a rudimentary plough, a modified tree branch used to scratch the surface of the soil and prepare it for planting. The plough was later adapted for pulling by oxen.
The hilly areas of south-western Asia and the forests of Europe had enough rain to sustain agriculture, but Egypt depended on the annual floods of the Nile to replenish soil moisture and fertility. The inhabitants of the so-called Fertile Crescent, around the Tigris and Euphrates rivers, also depended on annual floods to supply irrigation water. In China, the farmers who lived in the area near the Huang developed a system of irrigation and drainage to control the damage caused to their fields in the floodplain of the meandering river.
Although the Neolithic settlements were more permanent than the camps of hunting populations, villages had to be moved periodically in some areas, as the fields lost their fertility from continuous cropping. This was most necessary in northern Europe, where fields were produced by the slash-and-burn method of clearing. The settlements along the Nile, however, were more permanent, because the river deposited fertile silt annually. See also Archaeology.
B Historical Agriculture Through the Roman Period
With the close of the Neolithic period and the introduction of metals, the age of innovation in agriculture was largely over. The historical period—known through written and pictured materials, including the Bible, Near Eastern records and monuments, and Chinese, Greek, and Roman writings—was devoted to improvement. A few high points must serve to outline the development of worldwide agriculture in this era, roughly defined as 2500 bc to ad 500. Some plants became newly prominent. Grapes and wine were mentioned in Egyptian records about 2900 bc, and trade in olive oil and wine was widespread in the Mediterranean area in the 1st-millennium bc. Rye and oats were cultivated in northern Europe in about 1000 bc.
Many vegetables and fruits, including onions, melons, and cucumbers, were grown by the 3rd-millennium bc in Ur. Dates and figs were an important source of sugar in the Near East, and apples, pomegranates, peaches, and mulberries were grown in the Mediterranean area. Cotton was grown and spun in India about 2000 bc, and linen and silk were used extensively in 2nd-millennium China. Felt was made from the wool of sheep in central Asia and the Russian steppes.
The horse, introduced to Egypt about 1600 bc, was already known in Mesopotamia and Asia Minor. The ox-drawn four-wheeled cart for farm work and two-wheeled chariots drawn by horses were familiar in northern India in the 2nd-millennium bc.
C Tools, Storage, and Irrigation
Improvements in tools and implements were particularly important. Metal tools were longer lasting and more efficient, and cultivation was greatly improved by such aids as the ox-drawn plough fitted with an iron-tipped point, noted in the 10th-century bc in Palestine. In Mesopotamia, in the 3rd-millennium bc, a funnel-like device was attached to the plough to aid in planting seeds, and other early forms of drills were used in China. Threshing was done with animal power in Palestine and Mesopotamia, although reaping, binding, and sifting were still done by hand. Egypt retained hand seeding through this period, on individual farm plots and large estates alike.
Storage methods for oil and grain were improved. Granaries—jars, dry cisterns, silos, and bins of one sort or another containing stored grain—supported city populations. Indeed, without adequate food supplies and trade in food and non-food items, the high civilizations of Mesopotamia, northern India, Egypt, and Rome would not have been possible.
Irrigation systems in China, Egypt, and the Near East were elaborated, putting more land into cultivation. The forced labour of peasants and the bureaucracy built up to plan and supervise the work of irrigation were probably fundamental to the development of the city states of Sumer. Windmills and watermills, developed towards the end of the Roman period, increased control over the many uncertainties of weather. The introduction of fertilizer, mostly animal manures, and the rotation of fallow and crop land made agriculture more productive.
Mixed farming and stock raising were flourishing in the British Isles and on the continent of Europe as far north as Scandinavia at the beginning of the historical period, already displaying a pattern that persisted throughout the next 3,000 years. According to the region, fishing and hunting supplemented the food grown by agriculture.
C1 Beginnings of Serfdom
Shortly after the time of Julius Caesar, the Roman historian Cornelius Tacitus described the “Germans” as a tribal society of free peasant warriors, who cultivated their own lands or left them to fight. About 500 years later, a characteristic European village had a cluster of houses in the middle, surrounded by rudely cultivated fields comprising individually owned farmlands; meadows, woods, and wasteland were used by the entire community. The oxen and plough were passed from one field to another, and harvesting was a cooperative effort.
Rome appears to have started as a rural agricultural society of independent farmers. In the 1st millennium bc, after the city was established, however, agriculture started a capitalistic development that reached a peak in the Christian era. The large estates that supplied grain to the cities of the empire were owned by absentee landowners and were cultivated by slave labour under the supervision of hired overseers. As slaves, usually war captives, decreased in number, tenants replaced them. The late Roman villa of the Christian era approached the medieval manor in an organization; slaves and dependent tenants were forced to work on a fixed schedule, and tenants paid a predetermined share to the estate owner. By the 4th century ad, serfdom was well established, and the former tenant was attached to the land.
D Feudal Agriculture
The feudal period in Europe began soon after the fall of the Roman Empire, reaching its height about ad 1100. This period also saw the development of the Byzantine Empire and the power of the Saracens in the Middle East and southern Europe. Spain, Italy, and southern France, in particular, were affected by events outside continental Europe.
In the Arab period in Egypt and Spain, irrigation was extended to previously sterile or unproductive land. In Egypt, grain production was sufficient to allow the country to sell wheat on the international market. In Spain, vineyards were planted on sloping land, and irrigation water was brought from the mountains to the plains. In some Islamic areas, oranges, lemons, peaches, and apricots were cultivated.
Rice, sugar cane, cotton, and such vegetables as spinach and artichokes, as well as the characteristic Spanish flavouring saffron, were produced. The silkworm was raised, and its food, the mulberry tree, was grown.
By the 12th century, agriculture in the Middle East was static, and Mesopotamia, for example, fell back to subsistence level when its irrigation systems were destroyed by the Mongols. The Crusades increased European contact with Islamic lands and familiarized western Europe with citrus fruits and silk and cotton textiles.
The structure of agriculture was not uniform. In Scandinavia and eastern Germany, the small farms and villages of previous years remained. In mountainous areas and in the marshlands of Slavic Europe, the manorial system could not flourish. Stock raising and olive and grape culture were normally outside the system.
D1 The Manor
A manor required roughly 350 to 800 hectares (900 to 2,000 acres) of arable land and the same amount of other prescribed lands, such as wetlands, woodlots, and pasture. Typically, the manor was a self-contained community. On it was the large home of the holder of the fief—a military or Church vassal of rank, sometimes given the title lord—or of his steward. A parish church was frequently included, and the manor might make up the entire parish. One or more villages might be located on the manor, and village peasants were the actual farmers. Under the direction of an overseer, they produced the crops, raised the meat and draught animals, and paid taxes in services, either forced labour on the lord’s lands and other properties or forced military service.
A large manor had a mill for grinding grain, an oven for baking bread, fish ponds, orchards, perhaps a winepress or oil-press, and herb and vegetable gardens. Bees were kept to produce honey.
Woollen garments were produced from sheep raised on the manor. The wool was spun into yarn, woven into cloth, and then made into clothing. Linen textiles could also be produced from flax, which was grown for its oil and fibre.
The food served in a feudal castle or manor house varied—depending on the season and the lord’s hunting prowess. Hunting for meat was, indeed, the major non-military work of the lord and his military retainers. The castle residents could also eat domestic ducks, pheasants, pigeons, geese, hens, and partridges; fish, pork, beef, and mutton; and cabbages, turnips, carrots, onions, beans, and peas. Bread, cheese and butter, ale and wine, and apples and pears also appeared on the table. In the south, olives and olive oil might be used, often instead of butter.
Leather was produced from the manor’s cattle. Horses and oxen were the beasts of burden; as heavier horses were bred and a new kind of harness was developed, they became more important. The blacksmith, wheelwright, and carpenter made and maintained crude agricultural tools.
The cultivation regime was rigidly prescribed. The arable land was divided into three fields: one sown in the autumn with wheat or rye; a second sown in the spring with barley, rye, oats, beans, or peas; and the third left fallow, that is, unplanted. The fields were laid out in strips distributed over the three fields, and without hedges or fences to separate one strip from another. Each male peasant who was head of a household was allotted about 30 strips. Helped by his family and a yoke of oxen, he worked under the direction of the lord’s officials. When he worked in his own fields, if he had any, he followed village custom that was probably as rigid as the rule of an overseer.
D2 Crop Rotation
Around the 8th century, a four-year cycle of rotation of fallow land was introduced. The annual ploughing routine on 400 hectares would be 100 hectares ploughed in the autumn and 100 in the spring, and 200 hectares of fallow land ploughed in June. These three periods of ploughing, over the year, could produce two crops on 200 hectares in total, depending on the weather. Typically, ten or more oxen, no larger than modern heifers, were hitched to the tongue of the plough, often little more than a forked tree trunk. At harvest time, all the peasants, including the women and children, were expected to work in the fields. After the harvest, the community’s animals were let loose on the fields to forage.
Some manors used a strip system. Each strip, with an area of roughly 0.4 hectares (1 acre), measured about 200 m (220 yds) in length and from 1.2 to 5 m (4 to 16y ft) in width. The lord’s strips were similar to those of the peasants, distributed throughout good and bad field areas. The parish priest might have lands separate from the community fields or strips that he worked himself or that were worked by the peasants.
In all systems, the lord’s fields and needs came first, but about three days a week might be left for work on the family strips and garden plots. Wood and peat for fuel were gathered from the commonly held woodlots, and animals were pastured on village meadows. When surpluses of grain, hides, and wool were produced, they were sent to market to be sold.
D3 The Plague
Around the year 1300, a tendency to enclose the common lands and to raise sheep for their wool alone first became apparent. The rise of the textile industry made sheep-raising more profitable in England, Flanders, Champagne, Tuscany, Lombardy, and the region of Augsburg in Germany. At the same time, regions surrounding the medieval towns began to specialize in garden produce and dairy products. Independent manorialism was also affected by the wars of 14th- and 15th-century Europe and by the widespread plague outbreaks of the 14th century. Villages were wiped out, and much arable land was abandoned. The remaining peasants were discontented and attempted to improve their conditions.
With the decline in the labour force, only the best land was kept cultivated, and in southern Italy, for instance, irrigation helped to increase production on the more fertile soils. The emphasis on grain was replaced by diversification, and items requiring more care, such as wine, oil, cheese, butter, and vegetables, were produced.
E Scientific Agriculture
By the 16th century, the population was increasing in Europe, and agricultural production was again expanding.
The nature of agriculture there and in other areas was to change considerably in succeeding centuries. Several reasons can be identified. Europe was cut off from Asia and the Middle East by an extension of Turkish power. New economic theories were being put into practice, directly affecting agriculture. Also, continued wars between England and France, within each of these countries, and in German states consumed capital and human resources.
E1 Colonial Agriculture
A new period of exploration and colonization was undertaken to circumvent Turkey’s control of the spice trade, to provide homes for religious refugees, and to provide wealth for European nations convinced that only precious metals constituted wealth.
Colonial agriculture was carried out not only to feed the colonists but also to produce cash crops and to supply food for the home country. This meant cultivation of such crops as sugar, cotton, tobacco, and tea and production of animal products such as wool and hides.
From the 15th to the 19th centuries the slave trade provided the necessary labourers. Slaves from Africa worked, for instance, in the Caribbean area on sugar plantations and in North America on indigo and cotton plantations. Native Americans were virtually enslaved in Mexico, where a system known as peonage operated. Indentured slaves from Europe, and especially from the prisons of England, provided both skilled and unskilled labour in many American colonies. Ultimately, however, both slavery and serfdom were substantially wiped out in the 19th century.
When encountered by the Spanish conquistadors, the more advanced Native Americans in the New World had intensive agricultural economies but no draught or riding animals and no wheeled vehicles. Squash, beans, peas, and corn had long since been domesticated. The land was owned by clans and other kinship groups or by ruling tribes that had formed sophisticated governments, but not by individuals or individual families. Several civilizations had risen and fallen in Central and South America by the 16th century. Those met by the Spanish were the Aztec, Inca, and Maya.
E2 Breeding of Plants and Animals
The scientific revolution resulting from the Renaissance and the Age of Enlightenment in Europe encouraged experimentation in agriculture as well as in other fields. Trial-and-error efforts in plant breeding produced improved crops, and a few new strains of cattle and sheep were developed. The process of enclosure was greatly speeded up in the 18th century, and individual landowners could determine the disposition of land and of pasture, previously subject to common use. Crop rotation, involving alternation of legumes with grain, was more widely practised outside the village strip system inherited from the manorial period.
In England, where scientific farming was most efficient, enclosure brought about a fundamental reorganization of land ownership. From 1660 onward, the owners of the largest tracts of land had begun to add to their properties, frequently at the expense of small independent farmers. By the Victorian era, the agricultural pattern was based on the relationship between the landowner, dependent on rents; the farmer, producer of crops; and the landless labourer. Drainage brought more land into cultivation, and, with the Industrial Revolution, farm machinery was introduced.
E4 Mechanical Advances
It is not possible to fix a clear decade or series of events as the start of the agricultural revolution through technology. Among the important advances were the purposeful selective breeding of livestock, begun in the early 1700s, and the spreading of limestone on farm soils in the late 1700s. Mechanical improvements of the traditional wooden plough began in the mid-1600s with small iron points fastened on to the wood with strips of leather. In 1797, Charles Newbold, a blacksmith in Burlington, New Jersey, United States, introduced the cast-iron mould-board plough. The mould-board turns the soil and breaks it up, pushing it to one side; this type of plough is still the most widely used. John Deere, another American blacksmith, further improved the plough in the 1830s and manufactured it in steel.
Other notable inventions included the seed drill of the English agriculturist Jethro Tull, developed in the early 1700s and progressively improved for more than a century; the reaper of the American Cyrus McCormick in 1831; and numerous new horse-drawn threshers, cultivators, grain and grass cutters, rakes, and corn shellers. By the late 1800s, steam power was frequently used to replace animal power in drawing ploughs and in operating threshing machinery.
The demand for food for urban workers and raw materials for industrial plants produced a realignment of world trade. Science and technology developed for industrial purposes were carried over into agriculture, eventually resulting in the agribusinesses of the mid-20th century and beyond.
E5 Pest Control
In the 17th and 18th centuries, the first systematic attempts were made to study and control pests. Before this time, hand-picking and spraying were the usual methods of pest control. In the 19th century, poisons of various types were developed for use in sprays; biological controls such as the use of predatory insects were also used. Resistant plant varieties were cultivated; this was particularly successful with the European grapevine, in which non-resistant European grape-bearing stems were grafted on to resistant American rootstocks to defeat the Phylloxera aphid after it was accidentally introduced into France.
Improvements in transport affected agriculture enormously. Roads, canals, and railway lines enabled farmers to obtain necessary supplies and to market their produce over a wider area. Food could be protected in transport and shipped more economically than before as a result of rail, ship, and refrigeration developments of the late 19th and early 20th centuries. Efficient use of these developments led to increasing specialization and eventual changes in the location of agricultural suppliers. In the last quarter of the 19th century, for example, Australian and North American suppliers displaced European suppliers of grain in the European market. When grain production proved unprofitable for European farmers, or an area became more urbanized, specialization in dairying and cheesemaking became more common. Falling transport costs, and the resulting increase in trade and competition from abroad eventually led Western governments to introduce protective agricultural policies in the 20th century (see Protectionism).
F The Green Revolution
The impetus towards increased food production in the era following World War II was a result of a new population explosion. A so-called green revolution, involving selective breeding of traditional crops for high yields, new hybrids, and intensive cultivation methods adapted to the climates and cultural conditions of densely populated countries such as India, temporarily stemmed the pressure for more food. A worldwide shortage of petroleum in the mid-1970s, however, reduced the supplies of nitrogen fertilizer needed for the success of the new varieties. However, in the late 20th century, the adoption of these high-yielding varieties has, for example, led India to become a net exporter of products such as rice in some years. More recently, genetic modification of crops such as soya, maize, and cotton has allowed scientists to speed up the breeding process, allowing new crops to become available to farmers much faster. Characteristics such as herbicide resistance (in soya) and genes for producing substances toxic to insects (in maize and cotton) have been included in new varieties of crops. These have been adopted extensively by farmers in countries such as Argentina, China, and the United States. In the EU, genetically modified soya, maize, and oilseed rape can be used as food ingredients, although due to consumer fears, there is currently very little production of genetically modified crops in the EU.
Despite the ability of modern agriculture to produce high yields per hectare of land, erratic weather and natural disasters such as drought and floods continue to make world food supplies unstable. There are also increasing concerns about the sustainability of modern agriculture, as it requires high levels of energy and has substantial environmental impacts. Famine is also still widespread in many parts of the developing world, particularly in Africa. The problem is arguably not that world agriculture cannot produce enough food, but that many people do not have sufficient income to purchase the food that is already available. The challenge for the future will be to ensure sustainable food supplies and to achieve economic growth in countries such as those in Africa so that people can afford to buy the food that is produced. See Environment; Food Supply, World.