World’s Soil Resources

Following GLASOD, the need for more detailed and more country-specific degradation assessments
became apparent. In 1993, the members of the Asian Network on Problem Soils recommended the preparation
of a qualitative assessment for South and Southeast Asia at a scale of 1:5 million. This recommendation was
acknowledged by FAO and UNEP. FAO assigned ISRIC to prepare a new physiographic map and database
at 1:5 million scale. UNEP prepared and implemented the Assessment of the Status of Human-Induced Soil
Degradation in South and Southeast Asia (ASSOD). Sixteen national institutions for natural resources in the
region collaborated on the project under the coordination of ISRIC. The ASSOD project published revised subregional
Guidelines for General Assessment of the Status of Human-Induced Soil Degradation and produced
regional maps on the status of human-induced soil degradation at a scale of 1:5M together with digitized
version of the map (van Lynden and Oldeman, 1997).
The different soil degradation types inventoried by ASSOD are described below and shown in Figure 10.2:
• Water erosion: Water erosion covers 21 percent of the total land area in the region (or 46 percent of the
total degraded area). It is predominant in large parts of China (>180 million ha) except for the northern
parts, on the Indian subcontinent (>90 million ha) and in the sloping parts of Indochina (40 million ha),
the Philippines (10 million ha) and Indonesia (22.5 million ha). In relative terms, as a percentage of the
total country area, moderate to extreme water erosion is particularly important in India (10 percent),
the Philippines (38 percent), Pakistan (12.5 percent), Thailand (15 percent) and Vietnam (10 percent).
• Wind erosion: Wind erosion (9 percent of the total area, 20 percent of all degradation) is concentrated
mainly in the most western and northern arid and semi-arid desert regions of Pakistan (>9 million ha
on-site and >2 million ha off-site), India (20 million ha on-site, 3.6 million ha offsite) and China (>70
million ha on-site, >8.5 million ha off-site). Although large parts of these regions may be considered
deserts, some human-induced wind erosion was also reported.
• Chemical deterioration: Chemical deterioration is distributed in patches, probably also partly due to
different perceptions of this type of degradation. About 11 percent of the total area (or 24 percent of the
degraded area) is affected by some kind of chemical deterioration. High relative extents of chemical
deterioration (>30 percent of total country area) can be observed in Bangladesh, Cambodia, Sri Lanka,
Malaysia, Pakistan and Thailand, generally with negligible to light impact.
• Physical deterioration: Occurrence of physical deterioration (affecting about 4 percent of the total
area or 9 percent of the total degraded area) is even more dispersed and infrequent than chemical
deterioration. Waterlogging and aridification are the main subtypes, in particular in Bangladesh,
China, India and Pakistan. Compaction or crusting/sealing is relatively unimportant except in Thailand
and the Philippines, although they occur in most countries. Waterlogging and compaction as a result
of paddy cultivation are not considered as degradation. Loss of productive function as a result of
urbanisation, industrialisation and infrastructure has been indicated for only a few countries although
this phenomenon is on the rise.
Status of the World’s Soil Resources | Main Report Regional Assessment of Soil Changes
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in Asia