The earth could, in theory, feed very many more people than now inhabit the globe. But, in practice, good soils, favourable climates, rainfall and fresh water are unevenly spread around the world - and do not necessarily correspond to distribution of population. So while some countries can produce an excess of food, others struggle with inadequate resources. Many developing countries are overexploiting their soils and several need to wrest food from land poorly suited to agricultural production.

FAO has been mapping and assessing the world's land resources and agroclimates since the early 1960s. In the 1970s it began a decade-long study of 117 developing countries to see which could grow enough food on their available land for their populations. The study-carried out with the support of the United Nations Population Fund (UNFPA) and in collaboration with the International Institute for Applied Systems Analysis (IIASA) - calculated the numbers each country could theoretically support under a simplified scenario: use of all potentially arable rain-fed land (plus irrigated land) disregarding the needs for other uses, at three input levels - low (using traditional subsistence agriculture), intermediate (using some fertilizer and a combination of current and improved crop varieties) and high (the equivalent of Western European levels of farming).

It found, based on these assumptions, that even in 1975, 54 countries could not feed their populations with traditional methods of food production and 38 percent of the entire land area - home to 1 165 million people - was carrying more inhabitants than it could theoretically support. With populations projected to the year 2000, it estimated that 64 countries more than half the total would be facing a critical situation; at low input levels 38 would then be unable to support even half their projected populations. Twenty-eight of the 64 would cease to be critical if they could raise their agriculture to the intermediate level, as would another 17 if they could reach Western European standards. But 19 would still not be able to produce enough food, even then - and while some of these are wealthy enough to be able to import food, others are among the poorest countries on earth.

Much of the agricultural area of a country or a region has limitations (see chart) that may make it less suitable for arable farming. 1995 FAO estimates of arable land in use compared with the area potentially suitable show similarly wide differences between regions and countries, with some countries having essentially no arable land reserves, such as Tunisia and Burundi, and others having large amounts, for example Angola, Guyana and Brazil. Part of these gross land reserves are not available for conversion, however, because of other uses including forestry, grazing or conservation.

Against this background, FAO's 1995 study, World Agriculture: Towards 2010, estimated net cereal import requirements increasing from about 8 million tonnes to 19 million tonnes for sub-Saharan Africa; 38 to 71 million tonnes for the Near East and North Africa; 27 to 35 million tonnes for East Asia (excluding China); and 5 to 10 million tonnes for South Asia, primarily as a result of shortages of arable land.

Critical countries

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Countries with high levels of manufactured exports, mineral or fossil resources are more likely to be able to afford to import food and fertilizers. The map shows countries which, with differing levels of agricultural inputs such as fertilizers and irrigation, are projected to be dependent on food imports by the year 2000.

Cultivated areas and gross reserves

Land under cultivation and land with crop production potential in developing countries

Limitations on crop potential

Constraints on land with crop production potential in developing countries

World potential land use capabilities

Much of the land in developing countries is not suited to rainfed agriculture, but of the potentially productive land, only about one-third is cultivated. The scale of the map does not allow some important cropland areas, for example in West Africa, to be shown. Also, land shown as mainly suitable for one use may well be suited for other uses.

Agroclimatical information, when combined with soil data, indicates where crops can best be grown.

Five steps to getting the best use from the land

Climatic requirements of crops
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To help identify the optimum sustainable use for all cultivable land in the developing world, an FAO study demonstrated which land, down to 10 square kilometres, is best suited to each of the 11 major crops grown in the developing world. These data are of vital importance to developing world governments striving to provide food security for their populations.