Land degradation

Visualization of narrower problems
Degraded land
Damaged lands
Destruction of land resources
"Land degradation" is a catchall term covering such problems as wind and water erosion, soil pollution by urban wastes or pesticides, and the buildup of mineral salts caused by improper irrigation. There are eleven principal threats to land: agriculture, vegetation clearing, feral animals, fire, forestry, grazing, mining, salinization, tourism, urbanization and weeds.

Land degradation is 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.

The combination of rapid urban and industrial growth, extensive deforestation and unsustainable agriculture, including inadequate soil conservation, cultivation of steep slopes and overgrazing, has had a devastating impact on land resources.

The International Soil Reference and Information Centre (ISRIC), in the Netherlands, estimates that since 1945 Homo sapiens has degraded 17 percent of the world's land, not counting wastelands like Antarctica and the Gobi Desert. Two thirds of the devastated area will require major restoration.

Land degradation is a serious problem throughout Africa, threatening economic and physical survival. Key issues include escalating soil erosion, declining fertility, salinization, soil compaction, agrochemical pollution and desertification. An estimated 500 million hectares of land have been affected by soil degradation since about 1950, including as much as 65 per cent of agricultural land.

1. Land degradation has reduced fertility and agricultural potential. Replacing lost top soil takes centuries or even millennia. These losses have negated many of the advances made through expanding agricultural areas and increasing productivity.
The USA has the most carefully measured soil in the world. Every five years the U.S. Department of Agriculture evaluates the nation's land, county by county, in terms of something called "the universal soil loss equation," which assesses the soil movement in a given area. In the 1980s three independent studies used the data to estimate actual soil loss. All concluded that the peril to U.S. agriculture from erosion is negligible.

Even in Africa, the problem is bad luck, bad weather, and bad planning. Traditionally, African villagers held land in common, with access regulated by unwritten cultural rules. In those circumstances the people responsible for the management of the land take overuse into account, so they enforce rules of access that limit the use of the land. When modern crops and agricultural techniques appear, the system comes apart, because yields shoot high enough to give people a greater incentive to cheat. Population pressures exacerbate the problem by shrinking everyone's share of the common land. Add drought or ethnic conflict and the result is disaster. But African nations without drought or conflict have done increasingly well. The 1992 harvest in Nigeria was the biggest in twenty years. Given half a chance, people in Africa seem to make their own way.

As for other parts of sub-Saharan Africa, no one denies the famine there. Yet recent independent studies have found no long-term environmental consequences of the recent and devastating drought; the southern border of the desert, one study shows, is in about the same place it was eighty years ago, suggesting that the desert expands and contracts with little regard for its human inhabitants. The drought may have led to temporary overuse of common property, but the proper response would be to adjust land-use rules -- change the zoning, so to speak -- as societies did in other parts of Africa. That this has failed to occur in sub-Saharan Africa says more about the pervasive corruption, inefficiency, and civil turmoil there than about the inherent evils of breeding.

(C) Cross-sectoral problems