Page 50 - Soil Degradation, Conservation and Remediation

1.7 Soil Degradation 35

aimed to provide information (in the form of digitized maps) on soil and terrain
resources to the potential users in nontechnical terms. Since then (1991), important
regional inventories on land degradation were undertaken, notably in South and
Southeast Asia in close cooperation with national institutes in 17 Asian countries

and with technical and financial support from UNEP and FAO. In these surveys the

GLASOD methodology has been refined. The GLASOD map does not, however,
assess the vulnerability of land resources to the soil degradation process but the
status of degradation which assists policy makers and resource managers to identify
priority areas of intervention. The SOTER (Soil and Terrain Database) project was
initiated by the International Society of Soil Science in 1986; SOTER was devel-
oped as an internationally endorsed land resource information system that can store
at different levels, detailed soil and terrain attributes in such a way that these data
can be assessed, combined, and updated immediately and can be easily analyzed
from the point of view of potential land use, in relation to food requirements, envi-
ronmental impact, and conservation (van Lynden 2004 ). The LADA (Land
Degradation Assessment for Dryland Areas) project aims to develop and test an
effective methodology to assess causes, status, and impact of land degradation in
dry lands in order to improve decision making for sustainable development in dry
lands at local, national, subregional, and global levels. LADA is an international UN
initiative, supported by the Global Environment Facility (GEF), UNEP, UNCCD,
and FAO and is being executed by FAO. The Global Assessment of Land Degradation
and Improvement (GLADA) is intended to identify (1) the status and trends of land
degradation and (2) hotspots suffering extreme constraints or at severe risk, and,
also, areas where degradation has been arrested or reversed. Among other ongoing
activities to assess the status of soils in the world is the World Overview of
Conservation Approaches and Technologies (WOCAT). WOCAT is documenting
and evaluating soil and water conservation case studies worldwide. WOCAT has
developed a new internationally recognized standardized methodology, involving a
set of three comprehensive questionnaires, for documentation and evaluation of
individual soil water conservation technologies and approaches, and including area
coverage. The latter also includes assessment of soil degradation following a method
similar to GLASOD and ASSOD (Bai et al. 2008 , 2010 ).

1.7.3 Types of Soil Degradation

A world map on the status of human-induced soil degradation was published by
ISRIC, in cooperation with FAO and UNEP in 1991. In preparation of the map, a

general classification was developed, referred to as the GLASOD (Global

Assessment of Soil Deterioration) classification. According to GLASOD, there are
five main types of soil degradation, including water erosion, wind erosion, chemical

deterioration, physical deterioration, and degradation of biological activity
( Oldeman 1991 ). There are several subtypes of each type except biological degrada-
tion. These types and subtypes are mentioned below.