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Land and food

Desertification   Desertification is a significant threat to the arid, semiarid and dry sub-humid areas of the globe - the 'susceptible drylands' which cover 40 per cent of the Earth's land surface. Soil degradation in the drylands affects or puts at risk the livelihoods of more than 1 000 million people who are directly dependent on the land for their habitat and source of livelihood. Dryland soils are particularly vulnerable because they recover only slowly from disturbance. With a limited supply of water, new soil forms very slowly, salts once accumulated tend to remain where they are, and soils that are dry, poorly held together and sparsely covered by vegetation are susceptible to erosion. Infrequent rains are particularly erosive, especially where vegetation cover is sparse. Susceptible areas include the savannahs of Africa, the Great Plains and the Pampas of the Americas, the Steppes of southeast Europe and Asia, the outback of Australia and the margins of the Mediterranean. Some 1 035 million hectares, or 20 per cent of the world's susceptible drylands, are affected by human-induced soil degradation (UNEP/ISRIC 1991). Of this total, 45 per cent is affected by water erosion, 42 per cent by wind erosion, 10 per cent by chemical deterioration and 3 per cent by physical deterioration of the soil structure. Water erosion is the dominant form of degradation in semi-arid areas (51 per cent of total degradation) and dry sub-humid regions (also 51 per cent), and wind erosion is dominant in the arid zone (60 per cent). One major consequence of desertification is the development crisis affecting many dryland countries. Drylands still provide much of the world's grain and livestock, and form the habitat that supports the last remaining big game animals. The human population of the drylands lives in increasing insecurity as productive land per capita diminishes.

The Earth could, in theory, support far more than its present population but the distribution of good soils and favourable growing conditions does not match that of the population. The problem is being exacerbated by increasing land degradation caused by deforestation, poor management of arable and pasture land, including over-use of fertilizers and pesticides, the clearance of marginal land for cultivation, poor management of watersheds and water resources, uncontrolled dumping of wastes, deposition of pollutants from the air and poor land-use planning. Although land degradation is occurring all over the world, the problem is particularly serious where local food production cannot provide an adequate diet or even enough for bare survival. Their low agricultural yields and the pressures of high population growth have forced millions of small farmers to clear forests and cultivate fragile marginal lands, causing soil erosion and deepening rural poverty.

There is a lack of reliable data on land degradation but it is likely that soil degradation has affected some 1 900 million hectares of land worldwide (UNEP/ISRIC 1991). The largest area affected, about 550 million hectares, is in Asia and the Pacific. In China alone, between 1957 and 1990, the area of arable land was reduced by an area equal to all the cropland in Denmark, France, Germany and the Netherlands combined, mainly because of land degradation (ESCAP 1993).

In Africa, an estimated 500 million hectares of land have been affected by soil degradation since about 1950 (UNEP/ISRIC 1991) - including 65 per cent of the region's agricultural land (Oldeman 1994). Crop yields in Africa could be halved within 40 years if degradation of cultivated land continues at present rates (Scotney and Dijkhuis 1989). Land degradation affects about 300 million hectares of land in Latin America, as a result of soil erosion, loss of nutrients, deforestation, overgrazing and poor management of agricultural land (UNEP/ISRIC 1991). In Europe, some 12 per cent of the land area (115 million hectares) is affected by water erosion and some 4 per cent (42 million hectares) by wind erosion; in North America about 95 million hectares are affected by degradation, mainly erosion (UNEP/ISRIC 1991).

Calorie intake per capita (Click image to enlarge) Source: compiled by UNEP GRID Geneva from FAOSTAT 1997 and WRI, UNEP, UNDP and WB 1998

Calorie intake has generally increased over the past two decades but there were downturns in both Europe and Central Asia (as a result of political upheaval) and and in West Asia (as a result of war) during 1990-95

FAO projections for food supplies by region (FAO 1996) suggest that future problems will be concentrated in sub-Saharan Africa and South Asia, and that chronic under-nutrition is expected to affect 11 per cent of the population, or 637 million people in these countries in the year 2010. The countries projected to suffer from serious shortfalls in food supply are also those faced with rapidly growing populations and urbanization, low productivity agriculture, high debt and insufficient wealth to import food. Food availability in all other regions is projected to be adequate by the year 2010, as agricultural production growth is expected to keep pace with growing food requirements.

A particular problem, not only in developed countries, is the rising demand for meat, fish, poultry and dairy products, which encourages farmers to raise livestock. Growing fodder and feed crops for animals can displace subsistence food crops and is a less efficient use of land.

Since the 1970s, the FAO has been assessing the actual and potential areas of cultivated land in 117 developing countries to see which are or could become self-sufficient in food. There are some 2 500 million hectares of land in these countries that could be cultivated, of which about 760 million hectares are already under cultivation. By the year 2000, the FAO estimated that 64 countries would be facing a critical situation and, using traditional subsistence agriculture, 38 of these would be unable to support even half their projected populations (FAO 1995).

Global production of crops and livestock grew by 2.6 per cent in 1996. In developing countries, production in that year grew by 2.9 per cent, compared to 5.2 per cent in 1995, 5 per cent in 1994 and 4 per cent in 1993.

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