GLASOD
In 1987, the United Nations Environment Program (UNEP) requested an expert panel to produce, based on incomplete knowledge and in the shortest time possible, a scientifically credible global assessment of soil degradation (GLASOD). UNEP’s recommendation led to the publication of a world map on the status of human-induced soil degradation at a scale of 1:10 million. This map is based on input from more than 250 scientists on soil degradation in the 21 regions into which the world was divided for analytical purposes. UNEP’s immediate objective in producing the map was to help decision– and policy– makers better understand the dangers of inappropriate land and soil management.
GLASOD is criticized today as inaccurate, subjective, and not appropriate for assessing soil degradation at the country-level. Despite these drawbacks, it remains the only database to define the status of human-induced soil degradation and the extent of desertification at the global scale.
ASSOD
In response to requests for more detailed information on soil degradation, the Asia Network on Problem Soils in 1993 recommended preparation of a soil degradation assessment for South and Southeast Asia (ASSOD) at a scale of 1:5 million. The methodology of this assessment reflects comments from the peer review of GLASOD. As a result, ASSOD has a more objective cartographic base and uses the internationally endorsed World Soils and Terrain Digital Database (SOTER) to delineate mapping units.
Like GLASOD, ASSOD focuses on displacement of soil material by water or wind and in-situ deterioration of soil by physical, chemical, and biological processes. ASSOD, however, places more emphasis on trends of degradation and the effects of degradation on productivity. Although an improvement over GLASOD, ASSOD is not without problems. The assessment of the degree, extent, and recent past rate of soil degradation is still based on expert opinion, and the scale (1:5 million) is still not adequate to guide national soil improvement policies.
