FEEDING THE TEN BILLION
PLANTS AND POPULATION GROWTH
CAMBRIDGE UNIVERSITY PRESS 1998
Chapter 10: The Sixth Billion (1986-1998/9)
10.1 Introduction: the recognition of limits
In 1998/9, just 200 years after Malthus first published his Essay on the Principle of Population, the world population will reach 6 billion. That is six times more than the population he estimated in 1798, and probably beyond what he considered possible. Yet, in the twelve years it has taken for the sixth billion to arrive – mainly as a result of increases in China, India and Africa – the FAO indices of food production per head for the world as a whole have shown no decline.
Neither has there been a sustained rise in the food index for the world as a whole, such as that accompanying the preceding billion, although there has been some (10-14%) improvement in Asia and South America. Some observers have suggested, therefore, that surpassing a world population of five billion in the late 1980s may represent a turning point in the ability of global agricultural production to keep pace with population growth. Falls in food production per head have occurred in Africa and in some of the food-exporting developed countries where, faced with surpluses, governments have introduced measures to curtail production and reduce price supports and subsidies. The real world price for both wheat and rice remained generally low.
The annual growth rate of the irrigated area in Asia (two thirds of that in the world) fell from over 2.5% in the 1970s to 0.4% in the late 1980s, along with a massive reduction in lending and assistance for irrigation by the development banks. Contributing factors include the already large public and foreign debt loads of many developing countries, the falling availability of unexploited irrigation potential, and the rising chorus of resistance to irrigation on environmental grounds. But the major causes have probably been the reinforcing effects of declining world cereal prices and rising per hectare costs of irrigation development.
- Studies do not foresee further major expansions of irrigation, in which case our sixth billion may indeed mark a turning point in our dependence on rising yields and intensity of cropping to match population growth.
- Coinciding and interacting with the downturn in the extension of irrigation, there has also been a period of stasis in the global use of N, P and K fertilizers, particularly in Europe.
- Nor has the world’s arable area increased since 1986, small increases in the developing world being offset by decreases in the developed regions.
- The accumulation of our sixth billion has also seen a decline in the real value of public funding for agricultural research in many countries and also in the international agricultural research centers.
- There has been a noticeable shift of funding away from production-oriented research to a greater emphasis on the long-term sustainability of agriculture, stimulated by the 1987 Brundtland report on Our Common Future.
- While the emphasis is timely, sustainability is too often equated with low input agriculture, which would certainly not be sustainable in a world with a population that will grow to at least 10 billion.
- The advent of the first plants with genetically engineered resistances to insect pests, viral diseases and specific herbicides coincided with the world population reaching five billion.
- As the sixth billion arrives, the first commercial varieties with these resistances are being released, and it is too soon to estimate their likely impact on crop yields.
- So far there have been no transformations likely to raise yield potential in the staple cereals.
- Computer models and expert systems are being used increasingly to aid decision-making by the farmers, helped along by better forecasting of weather and markets and the more readily available positional and surveillance data needed for ‘precision farming’.
- The requisite increases in food production have come mostly from further increases in staple crop yields, but these have derived mainly from the continuing effects of advances made 20-30 years ago.
- They may soon be exhausted, and the use of other resources may be approaching their limit.
- As we pass the six billion mark it is still not clear how the ten billion will be fed, nor that famines have been banished, to which those in Ethiopia in 1991 and North Korea in 1997 bear witness.
10.2 Agronomic innovations
although there may not be a feast for us all at the world’s table, the cupboard is by no means bare as many pessimists would have us believe.
- Agricultural scientists have under test a great variety of innovations and new approaches to old problems. Some are of recent origin, others have their roots in research done long ago but still awaiting complementary developments in other areas.
- Rather than focusing on just one or two of these, I shall explore their variety.
Fertilizers were initially broadcast over the field, then drilled in with the seed, then placed in bands below or beside the seed or pelletted with it to improve early access to nutrients by the seedlings. Seeds have long been coated with fungicides to reduce seedling disease, or with rhizobial preparations to enhance the nodulation of legumes. To these are now being added coatings with macronutrients such as calcium or phosphorus, micronutrients such as molybdenum, hydrophilic substances to attract water, peroxides to provide oxygen, and antidotes to pre-emergence herbicides. The advantages of an early and healthy beginning of growth often persist through the crop cycle, so seed coatings are likely to become increasing complex.
Fertilizer formulations are likewise undergoing continual change, particularly in the directions of greater specificity for individual crops or environments, less likelihood of fixation or loss, slower release, etc. Nitrogenous fertilizers are by far the dominant component, about 60% of the world total, yet only 30-70% of the amount of N applied is commonly taken up be the crop in the first season. In wet environments or under irrigation, especially on light-textured soils in cool conditions which limit plant growth, much of the applied N leaches out as nitrate, with adverse effects on water quality and human health. One approach to reducing these losses has been the application of inhibitors of nitrification, such as nitrapyrin, which inhibit the conversion of ammonia to the more mobile and leachable nitrate. Given the overwhelming predominance of urea among the N fertilizers used in developing countries, losses by nitrification are a major problem in search still better solutions. With irrigated crops or flooded paddies, on the other hand, there is also the danger of substantial losses of N by ammonia volatilization unless the fertilizer is placed in the soil. Research into the conditions exacerbating such losses is leading to more effective agronomic management techniques.
- The age-old problems of pests and diseases of crops, which we have already visited several times, have provoked a great variety of new approaches arising from basic research to complement the continuing improvement of pesticides and their delivery, and the genetic engineering of resistances.
- The range of biological control agents continues to expand, e.g. in the use of fungal pathogens, protozoa and nematodes to control insect pests.
- Plant hormones and inhibitors of their synthesis or action are also being used to modify crop growth or reproduction to an increasing extent.
- Another area of agronomic advance is that of ‘precision farming’, also known as farming by satellite, site-specific management, variable rate technology, computer-aided farming, etc.
- Even this limited catalogue of current developments should indicate that the agronomic cupboard is by no means bare of innovation.
- As inputs and interactions multiply, farm management expertise becomes an ever more crucial element in crop production.
10.3 The challenge of improving photosynthesis
- Photosynthesis, the process by which water and atmospheric CO2 are converted into sugars through the tapping of solar energy by plants, rivals the most efficient photoelectric devices in energy conversion, but has to cope with changing and stressful conditions.
- Mankind has not yet succeeded in improving the efficiency of photosynthesis.
- Rubisco evolved about 3.8 million years ago. Since that time it has been exposed to extreme changes in atmospheric composition, from far higher to much lower CO2 levels, and to a rise in oxygen level largely as a result of its own activity.
- It is the most abundant enzyme in the world, constituting 20-25% of leaf protein, and its efficiency has undoubtedly been honed by prolonged and intense natural selection.
In these days of crop modification by genetic engineering, the ‘improvement’ of rubisco constitutes an irresistible challenge and would, if successful, would be a supreme achievement in the annals of biological endeavour, even though rising atmospheric CO2 levels are reducing the limitation of crop growth by this crucial enzyme.
10.4 The dilemmas of irrigation
- The central dilemma of irrigation is how to reconcile the declining share of total water use for irrigation with the increasing need for irrigation to enhance the effect of other inputs and raise yields and food production at the required rate.
- The period of most rapid expansion of irrigation coincided with the spread of the dwarf varieties of wheat and rice and with the greater use of nitrogenous fertilizers.
- Irrigation is also the key to further increases in cropping intensity, i.e. in the number of crops that can be grown per year, which may be an important source of greater food production at low altitudes in the coming years.
- Estimates of the proportion of the world’s food supply currently contributed by the irrigated areas range between a third and a half.
- Water is an increasingly scarce and valuable resource, and the share of it used for irrigation has declined from 90% in 1900 to less than 70% today.
- There is debate as to whether the era of rapid expansion has ended, with future emphasis to be placed on improvements in water use efficiency, or whether there will have to be further heavy investment in new (and old) systems.
- Irrigation is currently getting a bad press for several reasons: the limited life of many schemes; the problem of salination; the lowering of water tables; inefficiency; losses from transpiration; and health problems such as malaria and bilharzia.
- There is certainly scope for improvement but many are beyond the resources of the developing country farmers who use 70% of the world’s irrigation water.
- We shall probably see more investment in irrigation, but within the context of providing a more sophisticated and responsive irrigation service, with more equitable and timely deliveries under specified rights and managed by smaller entities, with charges for delivery.
10.5 Sustainability, the new watchword
- Agriculture has always had elements of a Faustian bargain in its trade-offs between productivity and sustainability.
- Many generations of farmers have sought to improve rather than mine their land, as exemplified by the old saying: ‘Live as if you would die tomorrow, farm as if you would live for ever.’
- Sustainable agriculture is not a luxury. When an agricultural resource base erodes past a certain point, the civilization it has supported collapses. There is no such thing as a post-agricultural society.
- Concerns have been how to maintain soil fertility, soil erosion, soil degradation, over-exploitation, salination and waterlogging, irrigation, use of fertilizers and agrichemicals, the intensification of agriculture, and loss of genetic resources.
- Currently the emphasis is shifting from the sustainability of agriculture to that of the whole biosphere and of the global environment.
- Poverty and underdevelopment are continuing major sources of environmental degradation, for which the poor often have no realistic alternative.
- Sustainable agriculture is not and cannot be equated with low input agriculture in a world with six to ten billion people to feed.
- Neither simplistic nor short-term solutions will suffice and long-term experiments are needed to provide the data on which long-term solutions can be based, particularly for the lower latitudes.
- Research on sustainability requires sustainability of funding for such research, and it is notable that the endless calls for the one are not matched by the supply of the other.
Chapter 11: What the World Eats Now