Cereals and us: time to renew an ancient bond
Climate change, environmental degradation and stagnating yields threaten cereal production and world food security. Sustainable crop production intensification can help to feed the world while protecting its natural resources
With a combined annual harvest of some 2.5 billion tonnes, maize, rice and wheat are the world's most widely cultivated crops and the foundation of world food security. Every day, humanity consumes millions of tonnes of those cereals in an almost endless variety of familiar forms - from steaming bowls of rice and plates of maize porridge to bread, tortillas, tamales, naan, chapatis, pasta, pizza, pies and pastries. Millions of tonnes more reach us by an indirect route, having been fed first to cattle, pigs and poultry that produce much of the world's meat, milk and eggs1, 2.
Together, maize, rice and wheat are the single most important item in the human diet, accounting for an estimated 42.5 percent of the world's food calorie supply. Globally, their contribution to our supply of protein - around 37 percent - is a close second to that of fish and livestock products. Wheat alone supplies more protein than the sum of poultry, pig and bovine meat. Maize, rice and wheat even supply 6 percent of the fat in our diets.
The three cereals are critical to food security in developing regions. In Southern Africa, they make up half the calorie supply. In Western Asia, wheat supplies around 40 percent of protein. In South Asia, wheat and rice account for half of all calories and protein and 9 percent of fat. In every developing region except Latin America, cereals provide people with more protein than meat, fish, milk and eggs combined.
Even in North America and Western Europe, where animal products make up almost two-thirds of the protein supply, wheat still represents more than 20 percent. Indirectly, cereals account for much more: in the United States of America, around 40 percent of the domestic maize supply - equivalent to some 130 million tonnes in 2014 - is fed to livestock2, 3.
Cereals have come to dominate human nutrition since the first farmers began to cultivate them before the dawn of history. In fact, the agricultural revolution and everything that followed - in short, the world we live in - have their origins in a curious and enduring bond first established some 10 000 years ago between communities of hunter-gatherers and abundant wild grasses of the Poaceae family. Among the first grasses to be sown and harvested, in the Middle East, were the Triticum species that gave rise, over a period of 2 500 years, to bread wheat4.
What the harvested grains offered hunter-gatherers was a concentrated source of energy, protein and other nutrients that could be easily stored. The same discovery was made in East Asia and West Africa, where the rice species Oryza sativa and Oryza glaberrima were domesticated from wild progenitors between 9 000 and 3 000 years ago5, 6. Today's 2 500 commercial maize varieties have their origins about 7 000 years ago, in Mesoamerica, in a grass of the genus Zea called teosinte4.
The invention of irrigation in Mesopotamia 8 000 years ago was a momentous first step in the intensification of cereal production, as expanding urban populations sought to meet their food needs by raising productivity. By 3 000 years ago, intensive paddy cultivation was practised in China4, and settlements in Mexico had developed irrigation systems for maize7.
If cereals provided the food security that allowed the human population to grow from 10 million to 300 million in the first 8 000 years of agriculture8, shortfalls in production or supply spelt disaster. Civilizations built on irrigated agriculture in the Indus and Tigris river valleys crumbled owing to the siltation of canals and the salinization of soils9. Famine devastated ancient Rome when enemies cut off shipments of grain from North Africa10. The Classic Mayan civilization collapsed probably owing to an epidemic of the maize mosaic virus11. In Europe, the end of the Medieval Warm Period 700 years ago was followed by wet summers which led to an upsurge in fungal diseases of wheat, triggering a famine that killed millions12.
The agricultural revolution in Britain, which began in the late seventeenth century, was another milestone in cereal production intensification and food security. Improved ploughs, more productive varieties and crop rotation with legumes helped farmers to maximize the use of on-farm resources and to double wheat yields, from 1 tonne to 2 tonnes per ha, between 1700 and 1850. In the same period, the population of England increased from 5 million to 15 million13, 14.
Population growth and agricultural intensification accelerated in the twentieth century. The years following the Second World War saw a paradigm shift in agriculture in industrialized countries, to the large-scale application of genetics, biochemistry and engineering to crop production. Great increases in productivity were achieved through the use of heavy farm machinery powered by fossil fuel, along with high-yielding crop varieties, irrigation and agrochemicals15.
The intensification of crop production in the developing world began in earnest in the 1960s, as exponential population growth, along with serious shortfalls in cereal production, led to widespread hunger15. By 1970, an estimated 37 percent of the developing world's population, or almost 1 billion people, were undernourished16, 17. Facing the threat of a world food crisis, the international community mobilized behind agricultural research, development and technology transfer initiatives that became known as the 'Green Revolution'. The focus was on intensifying production of the three crops fundamental to the world's food security: maize, rice and wheat.
The Green Revolution, and after
The Green Revolution was driven initially by the work of the American biologist Norman Borlaug and scientists at the International Maize and Wheat Improvement Center (CIMMYT) in Mexico and the International Rice Research Institute (IRRI) in the Philippines. It gathered momentum during the 1960s, with the introduction to South Asia of high-yielding, semi-dwarf rice and wheat varieties. Supported by government programmes to expand irrigation infrastructure and the supply of agrochemicals, those varieties produced, in a few short years, yield increases that had taken Britain's agricultural revolution more than a century to achieve1.
Thanks mainly to the Green Revolution, the world witnessed a quantum leap in food production. Annual global output of cereals grew from 640 million tonnes in 1961 to almost 1.8 billion tonnes by 2000. The biggest gains were in the developing world: output of maize rose by 275 percent, of rice by 194 percent and of wheat by 400 percent. Much of the increase in Asian rice production was due to higher cropping intensities, with farmers shifting from a single crop to as many as three crops a year18.
Although its population more than doubled between 1960 and 2000, the developing world boosted its per capita supply of cereals from domestic production, in the same period, by 50 percent1, 17. The proportion of undernourished fell from more than one-third of the population in 1970 to 18 percent by the end of the century19.
The lower unit production cost of cereals meant higher earnings for farmers, which contributed in Asia to a significant reduction in the incidence of rural poverty20. Urban consumers also benefited from decades of stable and relatively low cereal prices21. Intensification also meant that the 250 percent gain in the developing world's cereal production, between 1960 and 2000, was achieved with an expansion of the harvested area of only 44 percent, which reduced the need to convert natural habitat to farmland1.
Today, developing countries account for two-thirds of world cereal production1. Improved varieties are grown on most of the wheat lands in Asia and North Africa22, and in tropical Asia's rice fields23. In West Africa, early-maturing varieties have helped to double rice and maize production since 20001.
The contribution of the Green Revolution to food security is undeniable (Figure 1.1). The incidence of undernutrition in the developing world's population has fallen to 12.9 percent24. In 2014, world cereal production reached an estimated 2.5 billion tonnes, pushing international prices well below their peak of 201125. And there is potential for further production increases - in most developing regions, yields of major food crops, including cereals, are one-half of those that would be technically possible with optimization of inputs and management26.
The problem is that past agricultural performance is not indicative of future returns. Crop production intensification, based on monocropping and high levels of external inputs, has disrupted biodiversity and ecosystem services - including crop genetic diversity, soil formation and biological nitrogen fixation - to the point where it threatens the sustainability of food production itself27, 28. The Green Revolution's quantum leap in cereal production was often achieved at the cost of land degradation, salinization of irrigated areas, over-extraction of groundwater, the build-up of pest resistance, and damage to the wider environment, through increased emissions of greenhouse gases and nitrate pollution of water bodies15.
Intensive double and triple monocropping of rice in Asia is associated with the depletion of soil micronutrients, the build-up of soil toxicity and a high incidence of pests and diseases18. Rice yield increases have levelled off in East and Southeast Asia, which account for 60 percent of world production29. Declining growth in yields has been confirmed by studies in India's main rice-growing states and in East Asia's rice bowls. Mounting evidence points to diminishing returns to modern varieties, despite the high use of inputs20.
Yield stagnation in major wheat growing regions is seen as the result of a complex series of factors, including slowing rates of genetic enhancement, loss of soil fertility, declining input use-efficiency, and biotic and abiotic stresses22. The threat of wheat rusts has increased with higher cropping intensity and monocropping, while insect pests are increasingly responsible for wheat crop losses30.
Intensive crop production often creates lush environments highly favourable to pests, leading to an ever increasing need for pesticide as insects, weeds and pathogens build up resistance. Today, agriculture uses some 2.5 million tonnes of pesticide a year31. As early as the 1990s, the health costs of excessive pesticide use in Asian rice fields were found to be higher than the economic benefits of pest control32. Globally, some 220 weed species have evolved resistance to one or more herbicides, posing a particular threat to cereals33.
The worldwide adoption of high-yielding cereal varieties has led to the large-scale loss of plant genetic diversity and the erosion of biodiversity in general. The Green Revolution in Indonesia, for example, displaced some 1 000 local rice cultivars in favour of modern varieties which, owing to their narrow genetic base, are more vulnerable to pests and diseases. Monoculture has also reduced overall agrobiodiversity and dietary diversity, by replacing mixed farming of cereals, pulses and oilseed crops18, 20.
Intensive crop production also contributes significantly to the greenhouse gases responsible for climate change. Emissions from agriculture, and from land cover change mainly for agriculture, have almost doubled over the past 50 years34 and now account for up to 25 percent of total anthropogenic emissions35. Between 2001 and 2010, direct emissions from crop and livestock production grew from 4.7 billion to more than 5.3 billion tonnes of carbon dioxide equivalent, with most of the increase occurring in the developing countries34.
As a major user of mineral fertilizer, cereal production contributes heavily to agriculture's emissions of nitrous oxide, which amount to 58 percent of total emissions; flooded rice cultivation, along with livestock, is the source of almost half of all methane emissions36, 37.
Some critics say the Green Revolution benefited mainly those farmers who had better-endowed land and easier access to inputs and markets, and failed to reach the majority of small-scale, resource-poor farmers38. They point out the blinding paradox: that three-quarters of the world's poor and hungry live in rural areas and are employed mainly in agriculture and food production39, 40, 41.
Another criticism of the Green Revolution model of intensive agriculture is that its heavy costs to the environment were charged to future generations. No agencies were created to collect compensation and invest it in environmental rehabilitation. If farmgate prices reflected the full cost of production - with agriculture effectively paying for the environmental damage it caused - food prices would not have remained so low for so long15.
One thing is clear: despite the steady reduction in the proportion of undernourished in the world population, current food and agriculture systems have failed to provide everyone with the food they need for an active and healthy life. The absolute number of chronically undernourished in the world today is only 20 percent less than it was half a century ago24.
Meanwhile, an estimated 2 billion people suffer from micronutrient mal-nutrition as a result of vitamin and mineral deficiencies in their diets. Yield increases obtained with the massive use of mineral fertilizer, which provides mainly nitrogen, phosphorus and potassium, have coincided with a decline in the nutritional content of cereals42, and even of vegetable crops43, 44.
Among low-income rural households especially, monotonous diets high in starchy staples are the norm, and adequate amounts of micronutrient-rich foods, such as meat, dairy products, pulses, fruit and vegetables, are generally unavailable. Fifty years of intensive production of maize, rice and wheat may have improved the supply of dietary energy, but have not brought commensurate improvements to overall human nutrition45.
The Green Revolution model of crop production intensification was the right answer to the food crisis that faced humanity in the 1960s. But the world has now entered the 'post-Green Revolution era'.
More than three billion tonnes by 2050
World agriculture - and humanity's age-old bond with maize, rice and wheat - faces 'an unprecedented confluence of pressures'46. One is the demand for more food and other agricultural products than at any time in history. The global population is forecast to grow from 7.3 billion to more than 9.6 billion between now and 2050, with most of the increase in the developing regions; in the 48 least developed countries, population may double, to 1.8 billion17. Meanwhile, urbanization and rising affluence are driving a 'nutrition transition' in developing countries towards much higher consumption of animal protein, which will require big increases in livestock production and its intensive use of resources.
A new study by FAO and the Organisation for Economic Cooperation and Development (OECD) estimates that global consumption of cereals will increase by 390 million tonnes between 2014 and 2024. The core driver of the increase will be rising demand for animal feed, with coarse grains - of which about 70 percent is maize - accounting for more than half of the total. By 2024, developing countries will be consuming as food an additional 170 million tonnes of maize, rice and wheat47.
In the longer term, FAO has estimated that, by 2050, annual global demand for the three cereals will reach almost 3.3 billion tonnes. Much of the increase will be needed to fuel annual production of some 455 million tonnes of meat48, or 50 percent more than that produced in 20121. The use of cereals as biofuel feedstock has been projected to grow from the current 130 million tonnes a year to 182 million tonnes by 202048; under one scenario, it could reach almost 450 million tonnes by 205049, 50.
The demand for maize, rice and wheat does not need to be met entirely by production increases. Each year, one-third of all food produced for human consumption, including as much as 30 percent of cereals, is lost or wasted, with enormous negative effects on food availability and high environmental costs51. A substantial reduction in food losses and waste, along with a shift to healthier, sustainable diets less dependent on animal protein, would reduce the need to increase cereal production.
Nonetheless, the scale of future demand requires cereal farming systems that are both more productive and environmentally sustainable. Around 80 percent of future growth in crop production in developing countries will need to come from intensification; in South Asia, Western Asia and North Africa, intensification will account for between 90 and 100 percent of increases48. Agricultural growth will rely more than ever before on productivity gains through increased crop yields50.
Achieving cereal yield increases will, however, be more difficult than in the past. Most of the world's agro-ecosystems have been severely depleted of their soil organic carbon, the basis of soil fertility52. One-third of farmland is moderately to highly degraded owing to the erosion, salinization, compaction and chemical pollution of soils53. If soil erosion continues at its current rate in northeastern China, cereal production on 93 million ha of farmland could fall by 40 percent within 50 years54. The world's irrigated wheat production areas suffer increasingly from salinization and waterlogging22. In Asia and Latin America, expansion of the maize producing area is considered unsustainable owing to its high environmental costs and the risk of further land degradation55.
Meanwhile, agriculture's share of the world's freshwater withdrawals - currently around 70 percent - is under growing pressure from competing sectors. Many rainfed and irrigated cropping systems are approaching the limits of their production potential, and groundwater withdrawals exceed rates of natural replenishment in key cereal-growing areas worldwide53. In North Africa and Western Asia, water scarcity could be an even more important determinant of crop productivity than land scarcity56. Competition for water from domestic and industrial users is reducing the area under rice in some Asian countries23. Water scarcity is expected to lead to the diversion of irrigation from wheat to higher value crops, pushing wheat farming into less productive rainfed areas57.
Another constraint to production increases is the marked slow-down in the rate of growth in maize, rice and wheat yields, which averaged between 2 and 3 percent annually during the Green Revolution. While the global average growth in maize yields is 1.5 percent a year, owing mainly to gains in the United States, the growth rate has slipped to 1 percent for both rice and wheat - below the minimum required, by one recent estimate, to ensure world food security in 205050.
The slower growth in cereal productivity is linked to reduced incentives and demand for yield-enhancing technologies, owing to the substantial decline in the real prices of agricultural commodities from the early 1960s to the early 2000s58. Another factor is inadequate support to agriculture. The Green Revolution was made possible largely through research and development (R&D), input supply systems and extension services funded by governments15. But the growth rate of public spending on agricultural R&D in the developed world has slowed - and turned negative in the United States in 2004 - reducing technology spillovers to developing countries59, 60.
While annual public funding for agricultural R&D increased globally by 22 percent between 2000 and 2008, to reach US$31.7 billion61, China and India accounted for almost half of the increase; low-income countries' spending on agricultural R&D amounted to only 2.1 percent of the world total in 2009, less than in 196026.
The effects of climate change
Climate change, the most serious environmental challenge facing humanity, is expected to have far-reaching impacts on maize, rice and wheat. At a global level, it is estimated that higher temperatures and precipitation trends since 1980 have lowered yields of wheat by 5.5 percent and of maize by 3.8 percent below what they would have been had climate remained stable62. The coming decades are expected to see further increases in temperature, rising sea levels, more intense pest and disease pressures, water shortages, extreme weather events and loss of biodiversity63. A recent study of climate change impacts on agriculture found that, without adaptation by farmers, global crop yields in 2050 would be 6.9 percent below estimated yields without climate change; cereal yields would be lower by as much as 10 percent in both developed and developing regions (Figure 1.2)64.
Because maize is mainly a rainfed crop, higher rainfall variability will increase losses to drought and flooding in sub-Saharan Africa and Asia65, 66. Negative impacts will be felt most in areas where degraded soils no longer have the capacity to buffer crops against drought and heat stress55. Climate change is expected to reduce maize yields by increasing the incidence, severity and distribution of fungal diseases, which also pose a threat to food safety67.
Rice productivity in the tropics is forecast to decline. Today's high-yielding rice varieties are intolerant to major abiotic stresses that are likely to be aggravated by climate change, such as higher temperatures, drought and salinity. Rising sea levels and increased frequency of storms will pose a particular threat to rice-based systems in coastal regions68. Since river deltas in Bangladesh, Myanmar and Viet Nam have been responsible for half of rice production increases over the past 25 years, a serious loss of their production capacity would cause 'a major world food security crisis'69.
Increased frequency of short-term high temperatures could have catastrophic effects on wheat yields. Wheat lands in South and Western Asia and North Africa are projected to suffer the most from heat stress and water scarcity, and from upsurges of insect pests and soil-borne pathogens. In South Asia, the Indo-Gangetic Plains are currently a favourable mega-environment for wheat; by 2050, more than half of the total area may suffer from heat stress and higher rates of fungal diseases. Climate change could also reduce the nutritional content of wheat22, 70.
Growing pressure to reduce agriculture's own significant contribution to climate change will also affect cereal production. Climate change adaptation and mitigation will require cereal growers to limit the expansion of farmland, use less mineral fertilizer, and reduce methane emissions from rice fields by using less water37.
To reach the target of supplying 3.3 billion tonnes of cereals, annually, by 2050, yields of maize, rice and wheat do not need to improve at the same spectacular rates recorded during the Green Revolution. The issue is how profoundly the stagnation in cereal yields and that 'unprecedented confluence of pressures' - natural resources degradation, limited room for the expansion of cultivated land, water scarcity and the potentially catastrophic effects of climate change - will impact cereal production and world food security.
Severest impacts on the most vulnerable
Future scenarios indicate that the downward pressure on cereal production will affect disproportionately the most vulnerable. They include many of the developing world's 500 million small-scale and family farmers, who produce an estimated 80 percent of the world's food26, and the billions of low-income people who depend daily on cereals to survive.
While maize is used in the developed world mainly to feed livestock and produce biofuel, in many developing countries it is primarily consumed as food. Small-scale farmers in both sub-Saharan Africa and Mesoamerica generally grow maize as a food crop for household consumption and for sale in urban markets. Maize is particularly important in the diets of the rural and urban poor in sub-Saharan Africa and Latin America55. Rising demand for maize and declining maize productivity could lead, by 2050, to a tripling of the developing world's maize imports, at an annual cost of US$30 billion71.
Rice is a staple food for more than 3.5 billion people worldwide, with annual per capita consumption exceeding 100 kg in many Asian and some African countries. In both regions, rice is mainly a small farmer crop, with almost all of it produced on holdings ranging from 0.5 to 3 ha23. In Africa, soaring demand for rice among urban consumers is being met by imports, rather than domestic production; imports of milled rice almost tripled to 13.8 million tonnes between 2000 and 2012. West Africa alone accounts for some 20 percent of rice traded internationally72. Population growth will amplify the region's dependency, making African consumers ever more vulnerable to price increases23.
Declining wheat productivity and rising wheat prices will affect most severely those countries with high rates of poverty and high dependence on wheat for their food security30. In South Asia, where more than 90 percent of the wheat supply is used as food, around 60 percent of the population lives on less than US$2 a day; in Central Asia, where per capita wheat consumption is 160 kg a year, poverty rates range as high as 40 percent2, 73. African countries are increasingly dependent on wheat imports, which reached a record of 41 million tonnes in 2013/1474. As climate change pushes production into more favoured higher latitudes, the risks to the livelihoods of small-scale wheat growers will also escalate22.
The impact on the world's poorest populations of cereal price inflation in 2008 has sharpened awareness of the fragility of the global food system23. Wheat price hikes, for example, sparked urban riots in the Middle East and North Africa30. The current downward trend in cereal prices is expected to be short-term, with prices destined to stabilize above the relatively low levels recorded before 200847.
A study by the International Food Policy Research Institute (IFPRI) found that under a 'business as usual' scenario, with no change in current agricultural policies and investments, the real price of cereals could rise considerably between 2010 and 2050, slowing the reduction in the number of people at risk of hunger in many regions.
But the study offered another, more optimistic scenario: with sufficient levels of investment in increasing yields sustainably on existing farmland, the resulting higher productivity would keep inflation-adjusted cereal prices in 2050 very close to those of 2010 (Figure 1.3). Lower prices for maize would lead to a drop in the cost of milk and meat, while the lower cost of rice would relieve burdens on net food importers. Overall, productivity gains would improve food security in all regions, reducing the population at risk of hunger globally by around 40 percent21.
Save and Grow: Producing more with less
Raising yields sustainably on existing farmland is the essence of FAO's 'Save and Grow' model of crop production intensification. Save and Grow aims at overcoming today's intersecting challenges: boosting crop productivity and ensuring food and nutrition security for all, while reducing agriculture's demands on natural resources, its negative impacts on the environment, and its major contribution to climate change15. A solid body of evidence has shown that farm practices that conserve natural resources also increase crop productivity and enhance the flow of ecosystem services75-77.
The Save and Grow approach recognizes that food security will depend as much on ensuring sustainability as it will on raising crop productivity78. It seeks to achieve both objectives by promoting farming practices and technologies that protect the environment, make more efficient use of natural resources, reduce the momentum of climate change, contribute to rural livelihoods and benefit human health31, 79.
Ecosystem-based crop production is inherently climate-smart. It helps smallholders adapt to climate change by making their production systems more resilient to environmental stresses, such as drought, higher temperatures and upsurges in pests and diseases37. By maintaining and using a diversity of kingdoms, species and genepools in agro-ecosystems, it increases both productivity and resilience27.
Save and Grow also has great potential for mitigating climate change: by capitalizing on natural biological processes, it reduces the use of mineral fertilizer and cuts nitrous oxide emissions 'at source'; through more efficient use of water, it can help cut methane emissions from irrigated rice fields37. Management practices that restore soil health could sequester in the soil some 1.8 tonnes of carbon per ha annually80. Carbon sequestration has the potential to offset fossil fuel emissions by up to 1.3 billion tonnes of carbon a year, equivalent to 15 percent of global fossil fuel emissions81.
Much more attention needs to be given not only to the quantity, but also to the quality of the foods produced and consumed. Save and Grow promotes the diversification of smallholder production to include foods with a high content and bioavailability of nutrients - meat, dairy products, poultry and fish - which address multiple nutrient deficiencies, as well as pulses, fruit and leafy vegetables. Diversification increases the availability of a wider range of nutritionally dense foods, contributing directly to household food and nutrition security31.
Finally, higher productivity in smallholder agriculture is the key to equitable, broad-based socio-economic development in rural areas. It increases producers' incomes and demand for labour, diversifies sources of household income, improves access to food, and fosters rural industries. Empirical evidence shows that agricultural growth in many resource-poor, low-income countries can be five times more effective in reducing hunger and poverty than growth in other sectors82.
It is time to renew the bond between humanity and cereals. The Food and Agriculture Organization believes that Save and Grow is the way forward - indeed, the only viable option - for increasing maize, rice and wheat production sustainably. Chapter 2 of this book describes Save and Grow farming system components, practices and technologies, and reviews progress in their adoption by smallholder cereal growers in developing countries. Chapter 3 presents examples of integrated Save and Grow farming systems, in practice, from across the developing world. Chapter 4 concludes with an outline of the policy and institutional frameworks, and the innovations in technologies, education and capacity-building, needed to upscale the lessons learned in national and regional programmes.
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