NATIONAL SOIL AND LAND DEGRADATION MAPPING - 
REMOTE SENSING PERSPECTIVE 
L. Venkataratnam 
Agriculture & Soils Group 
National Remote Sensing Agency, Dept, of Space, Hyderabad 
INTRODUCTION 
The natural resources of a country are of primary 
importance for the development of economic life of its 
inhabitants and more specifically the soil resources 
because they are non-renewable vital resources for 
agricultural production and also for the development of 
non-agricultural sectors. The soils are highly vulnerable 
to degradation and nature takes very long period (say 
300 - 1000 years) to form an inch of the top fertile soil. 
Scientific management of soils is essential for the both 
continued agricultural productivity and protection of the 
environment. A pre-requisite for this is comprehensive 
information on soil resources in terms of types of soils, 
their spatial distribution, extent, their limitations viz., 
erosion, salinization / alkalization, water logging etc., 
and their potential / capabilities. This information is 
needed for a variety of purposes such as optimum land 
use planning, command area development, soil 
conservation in catchment areas, rainfed farming, 
watershed management, reclamation of degraded lands 
etc. This requires systematic characterization of soils, 
more accurate mapping of soils and developing rational 
and scientific criteria for interpretation of soil 
information for various land uses. Similarly, the 
information on the nature, extent, spatial distribution and 
magnitude of land degradation plays a vital role in 
planning strategies for reclamation / conservation of 
degraded lands. 
NEED AND SCALE OF MAPPING 
The soil maps are required on different scales 
varying from 1:1 million to 1:4000 to meet the 
requirements of planning at various levels (Table 1). 
Because the scale of a soil map has direct correlation 
with the information content and field investigations that 
are carried out. Small scale soil maps of 1:1 million are 
needed for macro level planning at National level. The 
soil maps at 1:250,000 scale provide information for 
planning at regional or state level with generalised 
interpretation of soil information for determining the 
suitability and limitations for several agricultural and 
non-agricultural uses and requires less intensity of soil 
observations and time. The soil maps at 1:50,000 scale 
where association of soil series are depicted, serve the 
purpose for planning resources conservation and 
optimum land use at district level and require moderate 
intensity of observations in the field. The large scale soil 
maps at 1:8,000 or 1:4,000 scale are specific purpose 
maps which can be generated through high intensity of 
field observations based on maps at 1:50,000 scale or 
large scale aerial photographs or very high resolution 
satellite data. Similarly, information on degraded lands 
like salt affected soils, eroded soils, water logged areas, 
jhum lands etc., is required at different scales Re 
planning strategies for reclamation and conservation of 
degraded lands. 
SOIL SURVEY STATUS IN THE COUNTRY 
Soil survey programme in India started during pre 
independence era and progressed significantly. Soil 
surveys are being carried out by various central and state 
level organizations. The soil surveys done till 1970 (20% 
of the area of the country) lacked correlation, uniform 
nomenclature and appropriate soil mapping units with 
legends. According to Report of the Task Force (1984) 
constituted by the Planning Commission, the total area 
surveyed in the country upto 1983 under detailed and 
reconnaissance soil surveys are 33.5 and I 15.0 million 
hectares, respectively. From late eighties onward, soil 
survey and mapping at 1:50,000 scale is being done by 
different agencies using satellite data and soil maps are 
used as critical input for generating action plans for 
development of land and water resources on sustainable 
basis. National Bureau of Soil Survey and Land Use 
Planning (NBSS & LUP) has prepared soil maps at 
1:250,000 scale for the whole country. Approximately 
l/3 ,d of the total geographical area of the country is 
already mapped at 1:50,000 scale by various organi 
zations under different projects. (Table 2) (DOS, 1999) 
Efforts are made by various agencies to identify 
various types of degraded lands, their spatial extent and 
severity levels (Table 3). According to National 
Commission on Agriculture (1976) 175 million hectares 
of land constituting 53.3 percent of the total geogra 
phical area of 329 million hectares are subject to some