Articles

The World Outlook for Conventional Agriculture

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Science  03 Nov 1967:
Vol. 158, Issue 3801, pp. 604-611
DOI: 10.1126/science.158.3801.604

Abstract

1) The worldwide demand for food will continue to be strong in the coming decades. Two forces—rapidly growing population and, in much of the world, rapidly rising incomes—are expected to result in increases in the demand for food even more rapid than those that have occurred during the past.

2) Conventional agriculture has assured an adequate food supply for the economically advanced one-third of the world. The challenge now is to assure an adequate food supply for the remaining two-thirds, where population is now increasing at the rate of 1 million people per week and where malnutrition is already widespread.

3) Economically feasible prospects for significantly expanding the world's area of cultivated land in the 1960's and 1970's are limited and largely confined to sub-Saharan Africa and the Amazon Basin. Even here, agronomic problems will limit the rate of expansion. When the cost of desalting seawater is substantially reduced—probably not before the late 1970's or early 1980's at best—it may become feasible to irrigate large areas of desert.

4) Given the limited possibilities for expanding the area of land under cultivation, most of the increases in world food needs must be met, for the foreseeable future, by raising the productivity of land already under cultivation. Food output per acre, rather static throughout most of history, has begun to increase rapidly in some of the more advanced countries in recent decades. All of the increases in food production over the past quarter century in North America, western Europe, and Japan have come from increasing the productivity of land already under cultivation. The area under cultivation has actually declined.

5) Achieving dramatic gains in land productivity requires a massive investment of capital and the widespread adoption of new technology. A similar effort must now be made in the less-developed nations if these nations are to feed their people. The most important single factor influencing this rate of investment is food prices, more particularly the relationship between the price farmers receive for their food products and the cost of modern inputs such as fertilizer.

6) In some of the more-developed countries where per-acre yields have been rising for a long time, there is now evidence that the rate of yield increase may be slowing. Nonrecurring inputs may have made their maximum contribution to output in the case of some crops, pushing yield levels past the middle of the S-shaped logistic curve. Although this cannot be determined with any certainty, the possibility that the middle of the curve has been passed in some instances should be taken into account in viewing the long-term future.

7) If the rate of increase in yield per acre does in fact begin to slow in some of the agriculturally advanced countries, additional pressure will be put on the less-developed countries—which have much of the world's unrealized food-production potential—to meet the continuing future increases in world food needs.

8) Man has not yet been able to bypass the process of photosynthesis in the production of food. This dependence on photosynthesis plays a significant role in determining the upper levels of the S-shaped yield curve. Additional research is urgently needed to increase the photosynthetic efficiency of crops and to raise the upper levels of economically feasible yields.

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