The history of agriculture records the domestication of plants and animals and the development and dissemination of techniques for raising them productively. Agriculture began independently in different parts of the globe, and included a diverse range of taxa. At least eleven separate regions of the Old and New World were involved as independent centers of origin.
Wild grains were collected and eaten from at least 20,000 BC. From around 9,500 BC, starting with figs, the eight Neolithic founder crops—emmer wheat, einkorn wheat, hulled barley, peas, lentils, bitter vetch, chick peas, and flax—were cultivated in the Levant. Rice was domesticated in China between 11,500 and 6,200 BC, followed by mung, soy and azuki beans. Pigs were domesticated in Mesopotamia around 11,000 BC, followed by sheep between 11,000 and 9,000 BC. Cattle were domesticated from the wild aurochs in the areas of modern Turkey and Pakistan around 8,500 BC. Sugarcane and some root vegetables were domesticated in New Guinea around 7,000 BC. Sorghum was domesticated in the Sahel region of Africa by 5,000 BC. In the Andes of South America, the potato was domesticated between 8,000 and 5,000 BC, along with beans, coca, llamas, alpacas, and guinea pigs. Bananas were cultivated and hybridized in the same period in Papua New Guinea. In Mesoamerica, wild teosinte was domesticated to maize by 4,000 BC. Cotton was domesticated in Peru by 3,600 BC. Camels were domesticated late, perhaps around 3,000 BC.
In the Middle Ages, both in the Islamic world and in Europe, agriculture was transformed with improved techniques and the diffusion of crop plants, including the introduction of sugar, rice, cotton and fruit trees such as the orange to Europe by way of Al-Andalus. After 1492, the Columbian exchange brought New World crops such as maize, potatoes, sweet potatoes, and manioc to Europe, and Old World crops such as wheat, barley, rice, and turnips, and livestock including horses, cattle, sheep, and goats to the Americas.
Since 1900, agriculture in the developed nations, and to a lesser extent in the developing world, has seen large rises in productivity as human labour has been replaced by mechanization, and assisted by synthetic fertilizers, pesticides, and selective breeding. The Haber-Bosch process allowed the synthesis of ammonium nitrate fertilizer on an industrial scale, greatly increasing crop yields. Modern agriculture has raised social, political, and environmental issues including water pollution, biofuels, genetically modified organisms, tariffs and farm subsidies. In response, organic farming developed in the twentieth century as an alternative to the use of synthetic pesticides.
Scholars have developed a number of hypotheses to explain the historical origins of agriculture such as the Hilly flanks hypothesis and Levantine primacy hypothesis. Studies of the transition from hunter-gatherer to agricultural societies indicate an antecedent period of intensification and increasing sedentism; examples are the Natufian culture in southwest Asia, and the Early Chinese Neolithic in China. Current models indicate that wild stands that had been harvested previously started to be planted, but were not immediately domesticated.
Localised climate change is the favoured explanation for the origins of agriculture in the Levant. When major climate change took place after the last ice age (c. 11,000 BC), much of the earth became subject to long dry seasons. These conditions favoured annual plants which die off in the long dry season, leaving a dormant seed or tuber. An abundance of readily storable wild grains and pulses enabled hunter-gatherers in some areas to form the first settled villages at this time.
Early people began altering communities of flora and fauna for their own benefit through means such as fire-stick farming and forest gardening very early. Exact dates are hard to determine, as people collected and ate seeds before domesticating them, and plant characteristics may have changed during this period without human selection. An example is the semi-tough rachis and larger seeds of cereals from just after the Younger Dryas (about 9,500 BC) in the early Holocene in the Levant region of the Fertile Crescent. Monophyletic characteristics were attained without any human intervention, implying that apparent domestication of the cereal rachis could have occurred quite naturally.
Agriculture spread from regions and began independently in different parts of the globe, and included a diverse range of taxa. At least 11 separate regions of the Old and New World were involved as independent centers of origin. Some of the earliest known domestications were of animals. Pigs were domesticated in Mesopotamia around 11,000 BC. Sheep were domesticated in Mesopotamia between 11,000 and 9,000 BC. Cattle were domesticated from the wild aurochs in the areas of modern Turkey and Pakistan around 8,500 BC. Camels were domesticated late, perhaps around 3,000 BC.
It was not until after 9,500 BC that the eight so-called founder crops of agriculture appear: first emmer and einkorn wheat, then hulled barley, peas, lentils, bitter vetch, chick peas and flax. These eight crops occur more or less simultaneously on Pre-Pottery Neolithic B (PPNB) sites in the Levant, although wheat was the first to be grown and harvested on a significant scale. At around the same time (9400 BC), parthenocarpic fig trees were domesticated.
By 7,000 BC, sowing and harvesting reached the fertile soil of Mesopotamia, where Sumerians systematized it and scaled it up. By 8,000 BC, farming was entrenched on the banks of the River Nile. About this time, agriculture was developed independently in the Far East, probably in China, with rice rather than wheat as the primary crop. Maize was domesticated from the wild grass teosinte in West Mexico by 6,700 BC. The potato (8,000 BC), tomato, pepper (4,000 BC), squash (8,000 BC) and several varieties of bean (8,000 BC onwards) were domesticated in the New World. Agriculture was independently developed on the island of New Guinea. In Greece from c. 11,000 BC lentils, vetch, pistachios, and almonds were cultivated, while wild oats and wild barley appear in quantity from c. 7,000 BC alongside einkorn wheat, barley, sheep, goats and pigs, while emmer was used on Cyprus between 9,100 and 8,600 BC. Banana cultivation of Musa acuminata, including hybridization, dates back to 5,000 BC, and possibly to 8,000 BC, in Papua New Guinea. Bees were kept for honey in the Middle East around 7,000 BC. Archaeological evidence from various sites on the Iberian peninsula suggest the domestication of plants and animals between 6,000 and 4,500 BC. Céide Fields in Ireland, consisting of extensive tracts of land enclosed by stone walls, date to 3,500 BC and are the oldest known field systems in the world. The horse was domesticated in the Pontic steppe around 4,000 BC. In Siberia, Cannabis was in use in China in Neolithic times and may have been domesticated there; it was in use both as a fibre for ropemaking and as a medicine in Ancient Egypt by about 2,350 BC.
In China, rice and millet were domesticated by 8,000 BC, followed by mung, soy and azuki beans. In the Sahel region of Africa, local rice and sorghum were domesticated by 5,000 BC. Kola nut and coffee were domesticated in Africa. In New Guinea, ancient Papuan peoples began practicing agriculture around 7,000 BC, domesticating sugarcane and taro. In the Indus Valley from the eighth millennium BC onwards at Mehrgarh, 2-row and 6-row barley were cultivated, along with einkorn, emmer, and durum wheats, and dates. In the earliest levels of Merhgarh, wild game such as gazelle, swamp deer, blackbuck, chital, wild ass, wild goat, wild sheep, boar, and nilgai were all hunted for food. These are successively replaced by domesticated sheep, goats, and humped zebu cattle by the fifth millennium BC, indicating the gradual transition from hunting and gathering to agriculture. Maize and squash were domesticated in Mesoamerica; potato in South America, and sunflower in the Eastern Woodlands of North America.
Sumerian farmers grew the cereals barley and wheat, starting to live in villages from about 8,800 BC. Given the low rainfall of the region, agriculture relied on the Tigris and Euphrates rivers. Irrigation canals leading from the rivers permitted the growth of cereals in large enough quantities to support cities. The first ploughs appear in pictographs from Uruk around 3,000 BC; seed-ploughs that funneled seed into the ploughed furrow appear on seals around 2300 BC. Vegetable crops included chickpeas, lentils, peas, beans, onions, garlic, lettuce, leeks and mustard. They grew fruits including dates, grapes, apples, melons, and figs. Alongside their farming, Sumerians also caught fish and hunted fowl and gazelle. The meat of sheep, goats, cows and poultry was eaten, mainly by the elite. Fish was preserved by drying, salting and smoking.
The civilization of Ancient Egypt was indebted to the Nile River and its dependable seasonal flooding. The river's predictability and the fertile soil allowed the Egyptians to build an empire on the basis of great agricultural wealth. Egyptians were among the first peoples to practice agriculture on a large scale, starting in the pre-dynastic period from the end of the Paleolithic into the Neolithic, between around 10,000 and 4,000 BC. This was made possible with the development of basin irrigation. Their staple food crops were grains such as wheat and barley, alongside industrial crops such as flax and papyrus.
Wheat and barley were domesticated in the Indian subcontinent by 7,000 BC, with jujube possibly as early as 9,000 BC, soon followed by sheep and goats. Barley and wheat cultivation—along with the domestication of cattle, primarily sheep and goats—followed in Mehrgarh culture by 8,000–6,000 BC. This period also saw the first domestication of the elephant. Pastoral farming in India included threshing, planting crops in rows—either of two or of six—and storing grain in granaries. By the 5th millennium BC, agricultural communities became widespread in Kashmir. Irrigation was developed in the Indus Valley Civilization by around 4,500 BC. The size and prosperity of the Indus civilization grew as a result of this innovation, leading to more thoroughly planned settlements which used drainage and sewers. Archeological evidence of an animal-drawn plough dates back to 2,500 BC in the Indus Valley Civilization.
Records from the Warring States, Qin Dynasty, and Han Dynasty provide a picture of early Chinese agriculture from the 5th century BC to 2nd century AD which included a nationwide granary system and widespread use of sericulture. An important early Chinese book on agriculture is the Chimin Yaoshu of AD 535, written by Jia Sixia. Jia's writing style was straightforward and lucid relative to the elaborate and allusive writing typical of the time. Jia's book was also very long, with over one hundred thousand written Chinese characters, and it quoted many other Chinese books that were written previously, but no longer survive. The contents of Jia's 6th century book include sections on land preparation, seeding, cultivation, orchard management, forestry, and animal husbandry. The book also includes peripherally related content covering trade and culinary uses for crops. The work and the style in which it was written proved influential on later Chinese agronomists, such as Wang Zhen and his groundbreaking Nong Shu of 1313.
For agricultural purposes, the Chinese had innovated the hydraulic-powered trip hammer by the 1st century BC. Although it found other purposes, its main function to pound, decorticate, and polish grain that otherwise would have been done manually. The Chinese also began using the square-pallet chain pump by the 1st century AD, powered by a waterwheel or oxen pulling an on a system of mechanical wheels. Although the chain pump found use in public works of providing water for urban and palatial pipe systems, it was used largely to lift water from a lower to higher elevation in filling irrigation canals and channels for farmland. By the end of the Han dynasty in the late 2nd century, heavy ploughs had been developed with iron ploughshares and mouldboards. These would slowly spread west, revolutionizing farming in Northern Europe by the 10th century. (Glick, however, argues for a development of the Chinese plough as late as the 9th century, implying its spread east from similar designs known in Italy by the 7th century.)
Asian rice was domesticated 8,200–13,500 years ago in China, with a single genetic origin from the wild rice Oryza rufipogon, in the Pearl River valley region of China. Rice cultivation then spread to South and Southeast Asia.
Ancient Greece and Hellenistic world
The major cereal crops of the ancient Mediterranean region were wheat, emmer, and barley, while common vegetables included peas, beans, fava, and olives, dairy products came mostly from sheep and goats, and meat, which was consumed on rare occasion for most people, usually consisted of pork, beef, and lamb. Agriculture in ancient Greece was hindered by the topography of mainland Greece that only allowed for roughly 10% of the land to be cultivated properly, necessitating the specialized exportation of oil and wine and importation of grains from Thrace (centered in what is now Bulgaria) and the Greek colonies of southern Russia. During the Hellenistic period, the Ptolemaic Empire controlled Egypt, Cyprus, Phoenicia, and Cyrenaica, major grain-producing regions that mainland Greeks depended on for subsistence, while the Ptolemaic grain market also played a critical role in the rise of the Roman Republic. In the Seleucid Empire, Mesopotamia was a crucial area for the production of wheat, while nomadic animal husbandry was also practiced in other parts.
In the Greco-Roman world of Classical antiquity, Roman agriculture was built on techniques originally pioneered by the Sumerians, transmitted to them by subsequent cultures, with a specific emphasis on the cultivation of crops for trade and export. The Romans laid the groundwork for the manorial economic system, involving serfdom, which flourished in the Middle Ages. The farm sizes in Rome can be divided into three categories. Small farms were from 18-88 iugera (one iugerum is equal to about 0.65 acre). Medium-sized farms were from 80-500 iugera (singular iugerum). Large estates (called latifundia) were over 500 iugera. The Romans had four systems of farm management: direct work by owner and his family; slaves doing work under supervision of slave managers; tenant farming or sharecropping in which the owner and a tenant divide up a farm’s produce; and situations in which a farm was leased to a tenant.
In Mesoamerica, wild teosinte was transformed through human selection into the ancestor of modern maize, more than 6,000 years ago. It gradually spread across North America and was the major crop of Native Americans at the time of European exploration. Other Mesoamerican crops include hundreds of varieties of locally domesticated squash and beans, while cocoa, also domesticated in the region, was a major crop. The turkey, one of the most important meat birds, was probably domesticated in Mexico or the U.S. Southwest.
In Mesoamerica, the Aztecs were active farmers and had an agriculturally focused economy. The land around Lake Texcoco was fertile, but not large enough to produce the amount of food needed for the population of their expanding empire. The Aztecs developed irrigation systems, formed terraced hillsides, fertilized their soil, and developed chinampas or artificial islands, also known as "floating gardens". The Mayas between 400 BC to 900 AD used extensive canal and raised field systems to farm swampland on the Yucatán Peninsula.
In the Andes region of South America, with civilizations including the Inca, the major crop was the potato, domesticated approximately 7,000–10,000 years ago. Coca, still a major crop to this day, was domesticated in the Andes, as were the peanut, tomato, tobacco, and pineapple. Cotton was domesticated in Peru by 3,600 BC. Animals were also domesticated, including llamas, alpacas, and guinea pigs.
The indigenous people of the Eastern U.S.A. domesticated numerous crops. Sunflowers, tobacco, varieties of squash and Chenopodium, as well as crops no longer grown, including marsh elder and little barley, were domesticated. Wild foods including wild rice and maple sugar were harvested. The most common varieties of strawberry were domesticated from Eastern North America. Two major crops, pecans and Concord grapes, were utilized extensively in prehistoric times but do not appear to have been domesticated until the 19th century.
The indigenous people in what is now California and the Pacific Northwest practiced various forms of forest gardening and fire-stick farming in the forests, grasslands, mixed woodlands, and wetlands, ensuring that desired food and medicine plants continued to be available. The natives controlled fire on a regional scale to create a low-intensity fire ecology which prevented larger, catastrophic fires and sustained a low-density agriculture in loose rotation; a sort of "wild" permaculture.
A system of companion planting called the Three Sisters was developed in North America. Three crops that complemented each other were planted together: winter squash, maize (corn), and climbing beans (typically tepary beans or common beans). The maize provides a structure for the beans to climb, eliminating the need for poles. The beans provide the nitrogen to the soil that the other plants use, and the squash spreads along the ground, blocking the sunlight, helping prevent the establishment of weeds. The squash leaves also act as a "living mulch".
From the time of British colonization of Australia in 1788, Indigenous Australians were characterised as nomadic hunter-gatherers who did not engage in agriculture, despite evidence to the contrary. In 1969, the archaeologist Rhys Jones proposed that Indigenous Australians engaged in systematic burning as a way of enhancing natural productivity, what has been termed fire-stick farming. In the 1970s and 1980s archaeological research in south west Victoria established that the Gunditjmara and other groups had developed sophisticated eel farming and fish trapping systems over a period of nearly 5,000 years. The archaeologist Harry Lourandos suggested in the 1980s that there was evidence of 'intensification' in progress across Australia, a process that appeared to have continued through the preceding 5,000 years. These concepts led the historian Bill Gammage to argue that in effect the whole continent was a managed landscape.
In two regions of Australia, the central west coast and eastern central Australia, forms of early agriculture may have been practiced. People living in permanent settlements of over 200 residents sowed or planted on a large scale and stored the harvested food. The Nhanda and Amangu of the central west coast grew yams (Dioscorea hastifolia), while various groups in eastern central Australia (the Corners Region) planted and harvested bush onions (yaua - Cyperus bulbosus), native millet (cooly, tindil – Panicum decompositum) and a sporocarp, ngardu (Marsillea drumondii).:281–304
Middle Ages and Early Modern
From the 8th century, the medieval Islamic world underwent a transformation in agricultural practice, described by the historian Andrew Watson as the Arab Agricultural Revolution. This transformation was driven by a number of factors including the diffusion of many crops and plants along Muslim trade routes, the spread of more advanced farming techniques, and an agricultural-economic system which promoted increased yields and efficiency. The shift in agricultural practice changed the economy, population distribution, vegetation cover, agricultural production, population levels, urban growth, the distribution of the labour force, cooking, diet, and clothing across the Islamic world. Muslim traders covered much of the Old World, and trade enabled the diffusion of many crops, plants and farming techniques across the region, as well as the adaptation of crops, plants and techniques from beyond the Islamic world. This diffusion introduced major crops to Europe by way of Al-Andalus, along with the techniques for their cultivation and cuisine. Sugar cane, rice, and cotton were among the major crops transferred, along with citrus and other fruit trees, nut trees, vegetables such as aubergine, spinach and chard, and the use of spices such as cumin, coriander, nutmeg and cinnamon. Intensive irrigation, crop rotation, and agricultural manuals were widely adopted. Irrigation, partly based on Roman technology, made use of noria water wheels, water mills, dams and reservoirs.
The Middle Ages saw further improvements in agriculture. Monasteries spread throughout Europe and became important centers for the collection of knowledge related to agriculture and forestry. The manorial system allowed large landowners to control 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.
By AD 900, developments in iron smelting allowed for increased production in Europe, leading to developments in the production of agricultural implements such as ploughs, hand tools and horse shoes. The carruca heavy plough improved on the earlier scratch plough, with the adoption of the Chinese mouldboard plough to turn over the heavy, wet soils of northern Europe. This led to the clearing of northern European forests and an increase in agricultural production, which in turn led to an increase in population. At the same time, some farmers in Europe moved from a two field crop rotation to a three field crop rotation in which one field of three was left fallow every year. This resulted in increased productivity and nutrition, as the change in rotations permitted nitrogen-fixing legumes such as peas, lentils and beans. Improved horse harnesses and the whippletree further improved cultivation.
Crops included wheat, rye, barley and oats. Peas, beans, and vetches became common from the 13th century onward as a fodder crop for animals and also for their nitrogen-fixation fertilizing properties. Crop yields peaked in the 13th century, and stayed more or less steady until the 18th century. Though the limitations of medieval farming were once thought to have provided a ceiling for the population growth in the Middle Ages, recent studies have shown that the technology of medieval agriculture was always sufficient for the needs of the people under normal circumstances, and that it was only during exceptionally harsh times, such as the terrible weather of 1315–17, that the needs of the population could not be met.
After 1492, a global exchange of previously local crops and livestock breeds occurred. Maize, potatoes, sweet potatoes and manioc were the key crops that spread from the New World to the Old, while varieties of wheat, barley, rice and turnips traveled from the Old World to the New. There had been 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 a lasting effect on many cultures. Maize and cassava were introduced from Brazil into Africa by Portuguese traders in the 16th century, becoming staple foods, replacing native African crops.
After its introduction from South America to Spain in the late 1500s, the potato became a 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 increased supply of food reduced disease, increased births and reduced mortality, 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 an arsenic compound used to fight Colorado potato beetles. Before the adoption of the potato as a major crop, the dependence on grain had caused repetitive regional and national famines when the crops failed, including 17 major famines in England between 1523 and 1623. The resulting dependence on the potato however caused the European Potato Failure, a disastrous crop failure from disease that resulted in widespread famine and the death of over one million people in Ireland alone.
British agricultural revolution
Between the 16th century and the mid-19th century, Britain saw a large increase in agricultural productivity and net output. New agricultural practices like enclosure, mechanization, four-field crop rotation to maintain soil nutrients, and selective breeding enabled an unprecedented population growth to 5.7 million in 1750, freeing up a significant percentage of the workforce, and thereby helped drive the Industrial Revolution. The productivity of wheat went up from about 19 bushels per acre in 1720 to around 30 bushels by 1840, marking a major turning point in history.
Advice on more productive techniques for farming began to appear in England in the mid-17th century, from writers such as Samuel Hartlib, Walter Blith and others. The main problem in sustaining agriculture in one place for a long time was the depletion of nutrients, most importantly nitrogen levels, in the soil. To allow the soil to regenerate, productive land was often let fallow and in some places crop rotation was used. The Dutch four-field rotation system was popularised by the British agriculturist Charles Townshend in the 18th century. The system (wheat, turnips, barley and clover), opened up a fodder crop and grazing crop allowing livestock to be bred year-round. The use of clover was especially important as the legume roots replenished soil nitrates.
The mechanisation and rationalisation of agriculture was another important factor. Robert Bakewell and Thomas Coke introduced selective breeding, and initiated a process of inbreeding to maximise desirable traits from the mid 18th century, such as the New Leicester sheep. Machines were invented to improve the efficiency of various agricultural operation, such as Jethro Tull's seed drill of 1701 that mechanised seeding at the correct depth and spacing and Andrew Meikle's threshing machine of 1784. Ploughs were steadily improved, from Joseph Foljambe's Rotherham iron plough in 1730 to James Small's improved "Scots Plough" metal in 1763. In 1789 Ransomes, Sims & Jefferies was producing 86 plough models for different soils. Powered farm machinery began with Richard Trevithick's stationary steam engine, used to drive a threshing machine, in 1812. Mechanisation spread to other farm uses through the 19th century. The first petrol-driven tractor was built in America by John Froelich in 1892.
The scientific investigation of fertilization began at the Rothamsted Experimental Station in 1843 by John Bennet Lawes. He investigated the impact of inorganic and organic fertilizers on crop yield and founded one of the first artificial fertilizer manufacturing factories in 1842. Fertilizer, in the shape of sodium nitrate deposits in Chile, was imported to Britain by John Thomas North as well as guano (birds droppings). The first commercial process for fertilizer production was the obtaining of phosphate from the dissolution of coprolites in sulphuric acid.
Dan Albone constructed the first commercially successful gasoline-powered general purpose tractor in 1901, and the 1923 International Harvester Farmall tractor marked a major point in the replacement of draft animals (particularly horses) with machines. Since that time, self-propelled mechanical harvesters (combines), planters, transplanters 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 Haber-Bosch method for synthesizing ammonium nitrate represented a major breakthrough and allowed crop yields to overcome previous constraints. It was first patented by German chemist Fritz Haber. In 1910 Carl Bosch, while working for German chemical company BASF, successfully commercialized the process and secured further patents. In the years after World War II, the use of synthetic fertilizer increased rapidly, in sync with the increasing world population.
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. Other applications of scientific research since 1950 in agriculture include gene manipulation, hydroponics, and the development of economically viable biofuels such as ethanol.
In recent years there has been a backlash against the external environmental effects of conventional agriculture, resulting in the organic movement. Famines continued to sweep the globe through the 20th century. Through the effects of climactic events, government policy, war and crop failure, millions of people died in each of at least ten famines between the 1920s and the 1990s.
The historical processes that have allowed agricultural crops to be cultivated and eaten well beyond their centers of origin continues in the present through globalization. On average, 68.7% of a nation's food supplies and 69.3% of its agricultural production are of crops with foreign origins.
The Green Revolution was a series of research, development, and technology transfer initiatives, between the 1940s and the late 1970s. It increased agriculture production around the world, especially from the late 1960s. The initiatives, led by Norman Borlaug and credited with saving over a billion people from starvation, involved the development of high-yielding varieties of cereal grains, expansion of irrigation infrastructure, modernization of management techniques, distribution of hybridized seeds, synthetic fertilizers, and pesticides to farmers.
Synthetic nitrogen, along with mined rock phosphate, pesticides and mechanization, have greatly increased crop yields in the early 20th century. Increased supply of grains has led to cheaper livestock as well. Further, global yield increases were experienced later in the 20th century when high-yield varieties of common staple grains such as rice, wheat, and corn were introduced as a part of the Green Revolution. The Green Revolution exported the technologies (including pesticides and synthetic nitrogen) of the developed world to the developing world. Thomas Malthus famously predicted that the Earth would not be able to support its growing population, but technologies such as the Green Revolution have allowed the world to produce a surplus of food.
Although the Green Revolution significantly increased rice yields in Asia, yield increases have not occurred in the past 15–20 years. The genetic "yield potential" has increased for wheat, but the yield potential for rice has not increased since 1966, and the yield potential for maize has "barely increased in 35 years". It takes only a decade or two for herbicide-resistant weeds to emerge, and insects become resistant to insecticides within about a decade, delayed somewhat by crop rotation.
For most of its history, agriculture has been organic, without synthetic fertilisers or pesticides, and without GMOs. With the advent of chemical agriculture, Rudolf Steiner called for farming without synthetic pesticides, and his Agriculture Course of 1924 laid the foundation for biodynamic agriculture. Lord Northbourne developed these ideas and presented his manifesto of organic farming in 1940. This became a worldwide movement, and organic farming is now practiced in most countries.