There needs to be some justification for including a chapter on soil degradation in a general-purpose soils book. It may have been more appropriate to have titled the chapter 'Soil Use and Management'. However, such a chapter would inevitably have veered towards soil misuse and mismanagement. Thus it was thought more appropriate to examine the way in which the valuable resource, that is the soil body, is abused. Soil degradation seriously threatens agriculture and the natural environment. More than 97 per cent of the world's food comes from the land. Soil degradation, according to many authorities (e.g. Barrow, 1991; Blaikie and Brookfield, 1987), is now a major world environmental issue. Population and land-use pressures, especially the need to achieve greater agricultural productivity, are the main factors leading to degradation. Soil degradation affects from 30 to 50 per cent of the Earth's land surface. The scale of soil degradation worldwide has been examined by the Global Soils Degradation Data Base (GLASOD) project, executed by over 250 soil scientists from all over the world. This had the objective of 'strengthening the awareness of decision makers and policy makers on the dangers resulting from inappropriate land and

soil management to the global well being, and leading to a basis for the establishment of priorities for action programmes' (Oldeman, 1988: p. 1).