Outlook on Agriculture

Global population growth is generally considered to be one of the major driving forces of global change. Population changes, however, follow their own dynamics and can be influenced only marginally in the short run. This paper outlines the basic structure of these dynamics, including the important momentum of population growth. It also presents alternative population projections that show that in the long run much depends on fertility trends in the near future, and that a successful curbing of population growth will result in very rapid and significant population aging.

Birth rates are falling in much of the developing world. In the mid-1960s women in Asia, Africa and Latin America gave birth to an average of six children. Today, the average is about four—a drop of one-third. In some regions and countries the average is substantially lower, approaching levels in the developed world.

This remarkable decline in birth rates is no cause for complacency about rapid population growth, however, as the Look at it this way article in this issue, by Catley-Carlson, rightly observes. Average family size is still well above the 2.1 ‘replacement level ’—the number of children per couple that over the long run leads to zero population growth because each couple has only enough children to replace itself in the population. Thus world population, already about 5.5 billion, continues to grow. Even as the average number of children born per woman falls, population will continue to grow rapidly for many years because the number of women of childbearing age is rising as a result of previous high birth rates—a phenomenon that demographers call ‘population momentum ’.

That the world's population is growing larger in a hurry is not news. But it is something of a surprise to learn that birth rates have declined so rapidly in so many countries, including some that experts considered too poor and traditional for this to occur. In fact, birth rates have fallen much faster than experts expected. The Demographic and Health Surveys (DHS) and similar family planning surveys conducted in more than 40 developing countries since 1985 tell the story of this striking decline.

Dramatic increases during the 1980s in agricultural production, particularly in the developing world, are due to both the increased area under cultivation and growth in yields per unit area. However, growth in food production has failed to keep pace with population growth in the majority of countries surveyed, and especially in Africa. Changes in rural infrastructure, agricultural technology, environmental management and government policy will influence food production in the future, while food consumption patterns in developing countries will change as a result of population growth, urbanization and changing lifestyles. Shortfalls are likely to occur, especially in Africa, where the availability of new land for cultivation is declining. The pressures on food production will rise, unless efforts are increased to reduce population growth.

Human population in the world is projected to grow from about 5.2 billion in 1990 to around 8.0–8.5 billion 35 years hence in 2025. About 44% of the world's population lived in an urban setting in 1990 compared with 34% in 1960. By 2025 the proportion will have grown to 60%. These demographic shifts have had, and will continue to have, major implications for the way in which food is produced and in the sustainability of cropping systems and protection of ecological resources. Particular attention is required to the type of agro-ecological zone and the influence of urbanization.

Population growth can lead to increases in agricultural output per head on a more sustainable basis. This was the conclusion of Boserup in 1965. The powerful mechanisms she identified can be illustrated by a study of Machakos District, Kenya during 1930–1960, which shows that, if policies are supportive, agricultural and non-farm incomes grow faster than even the rapid population growth rate experienced in Africa. Land use capability is not fixed, but can be transformed by investment, new technologies and good management. Lack of investment and consequent degradation are most likely at low population densities. While the study cannot foretell the future, Java illustrates a similar theme at even higher densities. It is essential that research understands the position the farmer has reached, and contributes, with other sources of information, to the technologies he or she can choose.

The most pressing problems facing the world in the 21st century are considered to be population growth together with depletion of the world's resources, social instability, poverty in developing countries, consumerism and the division between North and South, None is held solely responsible, for all these factors interact, and all will contribute to the global challenge facing the next generation. The removal of barriers between North and South is called for, enabling a transfer of knowledge and technology from one to the other, Systems are required that do not squander materials and energy, and that provide for collaboration and cooperation between North and South in technical research and economic development, Only then will the ultimate goal of global sustainability be achieved.