Issues Magazine

Feeding the World with Grains

By Tony Fischer

The yield of grains, the source of much of the world’s food, has risen to exceed world population growth in the past 50 years, resulting in cheaper food for the world’s poor. Can this continue over the next 50 years as world population rises to just over nine billion?

Humanity has done well to increase grain production to match population growth. Until the middle of the last century, most of this growth came from opening up more arable land. Since the 1960s, however, the area of arable land has remained relatively steady while grain yields (the amount produced per unit area) have increased substantially.

Indeed, the rate of increase in yields has more than matched the rate of increase in population. This has meant that in many parts of the developing world, but particularly in eastern and south-eastern Asia and Latin America, food availability per person has improved while the real (inflation-adjusted) price of food has fallen steadily for more than 100 years. Under­nourished people are now concentrated in South Asia and sub-Saharan Africa.

Despite these advances, one billion people (out of today’s world population of 6.7 billion) remain seriously underfed. People in the poorest regions generally cannot afford to import food, even if it is available at a low price. For these people, the dramatic spike in food prices in 2008 made an already difficult situation much worse, resulting in food riots in several developing countries.

Prices have now declined but we appear to have reached the end of the long and hugely beneficial decline in real food prices. And, with the global population forecast to reach 9.2 billion by 2050, we will have our work cut out to prevent future price increases.

Only development, prosperity and peace can ensure that the world’s population peaks soon after 2050 and remains below 10 billion. Increased agricultural productivity is at the root of both alleviating food insecurity – physical or economic inability of access to sufficient, safe and nutritious food – and of driving the necessary development.

Staying Ahead of the Demand Monster

The challenge of supplying the world with grain is even greater than population growth alone suggests because, as countries develop, their citizens’ individual demand for food will increase. Furthermore, recent and projected growth in the production of biofuels will divert resources away from crop production. It is now estimated that 80–100% more agricultural production (compared with 2000) is needed by 2050 simply to keep real food prices steady. This equates to annual growth of 1.4%.

There are four main ways to increase grain production:

  • increasing arable land area through the conversion of woodlands and grasslands;
  • growing more crops per year on land already cropped (often achieved through the introduction of or increase in irrigation);
  • replacing lower yielding crops with higher yielding ones; and
  • increasing the yield of existing crops (also often achieved through irrigation).

Currently, the world has around 1.40 billion hectares (3.46 billion acres) of crop land. Increasing the arable land area is possible in Sub-Saharan Africa and South America but would entail further loss of woodland or native grasslands, thus threatening biodiversity conservation and boosting greenhouse gas emissions. The process is also expensive and the total area of good soil available for new cropping is limited; new arable land may increase the existing area by only 20%. At the same time we are losing existing arable land to urbanisation and irreversible degradation.

Developing and expanding irrigation systems is expensive, and in many places water resources are limited. Several Asian regions, such as South Asia and the north China plain, are overusing their available underground irrigation water, while there and in much of West Asia and the Middle East, growing industrial and urban demand and climate change will very likely reduce water currently available for irrigation.

Replacing crops has limited scope, and although this would increase diversity it is unlikely to increase food energy or kilojoule yield. It would also involve major dietary and cultural changes, such as switching from wheat and rice staples to maize, or switching from grain-fed animal products to grain itself.

Thus, increases in crop yield must be the major way forward if supply is to keep up with growing demand, real food prices are to remain low, and only some new land is to be opened up for cropping.

Past Increases in Grain Yield

Past progress in increasing grain yields offer us many lessons for the future. For individual crops at a global level, yield growth is strongly linear and upwards. But world yield figures for any crop hide huge differences in yield growth between regions, with developing countries in general, and Sub-Saharan Africa in particular, lagging well behind.

There are two notes of caution with respect to current yield change. First, the rate at which yields are increasing in general, especially in developed countries, is slowing. Second, yield growth rates of rice and wheat (both at 0.9% per year) are too low to meet future demand growth (the 80–100% increase by 2050 mentioned earlier). If this situation continues, prices will increase and make life even harder for the many poor consumers of these staple grains.

Future Farm Yield Increases

Several key factors drive growth in yields:

  • genetic improvement of the varieties grown;
  • better agronomic management of the crops (including better or increased use of inputs such as fertiliser, herbicides or pesticides; improved irrigation; and smarter timing of operations);
  • more skilful and better-resourced farmers (in terms of education and access to credit, for example) who are ready and able to adopt the products of the two previous factors;
  • improved roads and communications for access to inputs and markets; and
  • improved institutions that promote better rural education and health, and better rule of law as it pertains to land ownership, contracts and security.

Each of these factors is necessary but not sufficient for crop yield growth. In developed countries with a long tradition of agricultural research and development, such as Australia, USA or the European nations, the fourth and fifth factors no longer limit yields and the third factor is only a partial limitation. Over the past 50 years, most progress has come equally from the first and second factors. But in many poorer countries, especially in Sub-Saharan Africa, lack of progress in all five factors results in very low yields and rates of yield growth, and persistent under-nutrition.

Yields can be thought of in terms of farm yields (those achieved by farmers under prevailing conditions) and potential yields (those that can be obtained using the best varieties under optimum conditions for the given soil and weather). The gap between potential yield and farm yield tells us how far the farmers are behind the current best technology. Economic considerations generally prevent even skilful, well-resourced farmers reducing the gap to less than about 25% of farm yield (e.g. achieving 8.0 tonness per hectare when potential yield is 10.0 tonnes per hectare, as are the current numbers for wheat in the UK).

Gaps larger than 25% are common: typically they are 30–100% of farm yield, and often much higher in developing countries and for rain-fed crops in drier situations (where farmers have no access to irrigation infrastructure). In Sub-Saharan Africa and in some other poor nations, yields remain very low and gaps often exceed 100% and even 200%.

Future increases in farm yield are likely to come from two sources. The first is the closing of yield gaps, especially the large ones. The experience of developed nations allows us to be optimistic about what can be achieved with concerted efforts to advance all five factors listed above. The second source lies in raising the potential yield. In most relatively modern farming systems, increases in potential yield are associated with increases in farm yield, even if the yield gap itself doesn’t change. In this context, climate change threatens to throw an additional spanner in the works. Projections suggest that climate change will reduce potential yield (and hence farm yield) in more environments than it is likely to increase them, although considerable uncertainty surrounds these predictions.

Closing the Yield Gaps

To close the major yield gaps seen in many developing countries, we need high quality research, effective extension (dissemination of technologies and knowledge) and good policy. The key elements include the following:

  • Breeding. An example is breeding for better resistance to biotic stresses such as diseases, viruses and insects. Genetic modification is already making an impact here. Improved varieties that are resistant to pests or tolerant of environmental stresses (such as drought or salinity) do not necessarily have higher potential yields, but they close the yield gap by reducing losses and helping farmers to focus on crop management that increases yields.
  • Adoption of improved technologies. This relates to the second and fifth factors listed above, and involves giving all farmers (especially those in developing countries) access to technologies that, for the most part, already exist in developed countries. Such technologies – which may need to be modified for developing-country conditions and which necessitate farmer training and on-farm demonstrations – include herbicides, machinery and good quality seeds of improved crop varieties.
  • Improved rural infrastructure and institutions. This includes irrigation systems, roads (which improve transport and allow farmers easier access to markets), modern communications, and even education- and health-related infrastructure, such as schools and hospitals. Other factors include better systems of land tenure, improved overall security, increased access to credit, and transparent and trustworthy market chains.

The challenge in closing gaps is to bring together all the necessary elements of a modern agricultural system: crop science, rural sociology, social economics and policy. Enlightened public-sector extension, the private sector and farmer organisations all play vital roles in achieving this. Progress in rice yields in Egypt shows what can be achieved given good research, extension and the right policies.

Raising Yield Potential

Breeders have made steady progress in yield improvements over the past 100 years using conventional breeding methods (repeated cycles of parent selection, hybridisation between desirable parents, then selection and yield testing of progeny). All of the early improved varieties were so-called inbreds, the progeny of which are genetically identical to their parents, thus allowing farmers to save seed each season for planting in the following season.

About 80 years ago, the discovery of hybrid vigour led to the development of hybrid varieties that possessed higher yield potential than their inbred counterparts. Hybrids – the first-generation progeny of a cross between genetically distinct parents – yield 10–20% higher than their parents, with this relative advantage actually being greater under stress.

In crop plants where it is possible to produce hybrid seed easily, all modern varieties are hybrids. Such crops include corn, sorghum, canola, sunflower, half of the rice in China, and a growing proportion of rice elsewhere. Farmers must buy seed every year but even small-scale farmers, if well-informed, can gain an advantage by using hybrids.

The annual rate of increase of potential yield through breeding progress for inbreds and hybrids alike has fallen to below 1% in almost all crops, and is in many cases closer to 0.5%. Thus breeding for yield alone is currently insufficient to meet growing world demand, but it remains an essential part of the solution (along with closing yield gaps). The big questions are: what is the possibility of increasing the rate of progress, and what is the biological limit to crop yield?

Nature has produced two distinct types of photosynthesis: the more primitive type is called C3 photosynthesis (named after the first detectable product of photosynthesis, a sugar with three carbon atoms), and is found in wheat, rice, soybeans and most other crops. C3 photosynthesis converts light to plant matter at about 70% of the efficiency achieved in the more recently evolved C4 photosynthesis found in sugar cane, maize, sorghum and millet (the only major C4 crops). C4 crops are generally better adapted to warmer conditions, but in areas where they can be grown alongside C3 crops they yield around 50% more grain and require less water and nitrogen (and therefore less fertiliser). One very ambitious project currently underway is attempting to transfer, through genetic modification, C4 photosynthesis into rice.

The second cause for hope is that within C3 crops there is considerable variation in photosynthetic rate, and recent conventional breeding for increased yield appears to have led to increased leaf photosynthesis. This suggests that targeted conventional breeding could lift photosynthesis further, and this is being pursued by researchers.

Crop production under water-limited conditions also deserves a mention. Crop varieties that yield as well as or better than normal under drought conditions would constitute a major breakthrough. Good progress has been claimed for genetically modified maize that uses a bacterial gene to achieve 6–10% higher yields under water-limited conditions that would ordinarily reduce yield by half.

More Nutritious Food

In developing countries, even people who consume enough kilojoules may suffer from malnutrition if their food is low in micronutrients. Although grains are generally healthy, a grain-dominated diet (characteristic of many people in poor regions) may not provide sufficient vitamins and minerals. Encouragingly, there is good potential to breed more nutritious crops.

So-called golden rice, which is high in beta-carotene (the precursor to vitamin A), is an example of a crop that has been genetically modified to be more nutritious. Deriving its beta-carotene from a maize gene, golden rice is scheduled for release in the Philippines around 2012. Many poor people in the developing world have diets dominated by polished rice and therefore tend to be deficient in vitamin A; golden rice would offer a practical alternative to supplements for such people.

High iron and zinc grains are being pursued by conventional breeding for other microelement-deficient poor consumers. Any genetically modified products will have to be tested thoroughly to ensure that they meet safety regulations, but they are very likely to be declared safe and thus place great pressure on opponents of genetically modified foods.

Privatisation of Crop Breeding

Breeding of major crops in the developed world is now largely dependent on breeding companies, most of which are private and dependent on royalties from seed sales. In the developing world, although crop breeding is still largely public (including the not-for-profit international crop centres), private breeding is on the rise.

Private breeding in the developing world is low but rising sharply, helped by the production of superior hybrid varieties and the spread of legislation permitting seed royalties and genetically modified crops.

Private breeding in developing countries is especially evident in Latin America, India and China. Involvement of such large multinational companies as Monsanto and Syngenta, or their affiliates, causes some concern about disproportionate market power. But with multinationals a fact of globalisation, it is their proper regulation that needs attention, for these organisations bring considerable advantages in terms of research investment, superior products, and their commitment to their client base, namely the farmers who plant their seeds. There will remain a need for public breeding for minor crops and for the poorest farmers and countries, but governments and aid agencies will be increasingly reluctant to divert scarce public funds to breeding areas that the private sector can handle.

Reaching All the Undernourished

The vast majority of the world’s undernourished are poor people in developing countries. These are often the landless and small subsistence farmers who are unable to produce enough food to feed themselves and their families. Increases in global productivity may reduce the price of food but, even when prices drop, the poor often cannot afford all that they need. Food price increases, in contrast, are disastrous.

There is a dilemma for the development community: efforts to bring improved seeds and technologies to the poorest rural communities, although reaching the neediest, benefit few beyond these communities. Efforts targeting the commercial farming sector, on the other hand, can provide bigger boosts in production and benefit more people, both directly and indirectly.

Except in parts of Latin America, commercial producers are very small by western standards, but they were the farmers who spearheaded the Green Revolution in Asia in the 1960s and 1970s, which saw the introduction of modern crop varieties and farming techniques and attendant boosts in productivity. These farmers effectively became the engine of economic growth and development in Asia, starting with increased rural incomes for farmers and the landless alike, followed closely by increased rural non-farm industry.

As development proceeds, labour will inevitably migrate from agriculture to non-agricultural industry, first rural and later urban. This process has accompanied development everywhere, with all its attendant disruption but also its opportunities for people to do better and to earn enough income to banish food insecurity. It is hard to see another model for the world, and certainly few small farmers want their children to be farmers.

It needs to be remembered that the primary basis for development has been, and is likely to remain, improved agricultural productivity – in particular grain productivity – arising from new crop varieties and better ways of growing them. The best possible agricultural science will continue to play a truly vital role in the future.