Population, nutrition and agriculture

Abstract

The human carrying capacity of the world or a country is considered as a function of food consumption per capita. A method of assessing carrying capacity is described, and it is shown that the world’s population currently exceeds the global carrying capacity, that the population of the less-developed countries (LDCs) exceeds their carrying capacity, and that this situation cannot be expected to change more than marginally in the period up to 2050. It is also shown that a major increase in the global consumption of nitrogen fertilizer will be necessary if world crop production per capita is to be maintained at the current inadequate level.

Appendix: Cereal yields

The highest maize, wheat and rice yields achieved on single fields or experimental plots are shown in Table 3. The maize yield was achieved by Steven Albracht, the winner in the Irrigated Class of the 2005 U.S. Corn Yield Contest. The wheat and rice yields were obtained on experimental plots.

Table 3 World record maize, wheat and rice yields

Table 4 shows the highest yields achieved for the three major cereals in large-scale agriculture.

Table 4 Highest yields of maize, wheat and rice in large-scale agriculture

Table 5 shows the global yield, harvested area and production for the three principal cereals and for all cereals in 2004 (a record year), and the provisional figures for 2005. Of the 37 countries included in Fig. 1, the highest national average cereal yield in 2004 was achieved in Egypt, with 7.55 t/ha. France was a close second with 7.54 t/ha. The lowest yield was in Sudan, with 0.40 t/ha.

Table 5 World cereal yields, harvested areas and production, 2004 and 2005

The 1985–2005 regression line for global cereal yield is 2.47 + 0.040T t/ha, where T is the number of years after 1985. If this trend were to continue, the yield in 2050 would be 5.07 t/ha, appreciably higher than the 4.28–4.58 t/ha projected by the author.