Digital database of salt affected soils in India using Geographic Information System

Abstract

Salt affected soils were mapped on 1:250000 scale, based on the interpretation of remote sensing data, ground truth and laboratory analysis for pH, ECe and ESP. These maps covering fifteen states (printed on 125 paper sheets) contained voluminous data on spatial coverage, physiography and categories of salt affected soils following USDA approach. In analog form such data is difficult to handle for users of varied background and interest. For easy access, quick retrieval and spatial analysis with multiple thematic layers, the analog maps were georeferenced and digitized to develop theme layers of salt affected soils and basemap comprising of infrastructure (roads/railways), irrigation/drainage (canal/river), settlements (State/district capitals) and political/ administrative boundaries. Such maps prepared for fifteen states were integrated in Geographic Information System (GIS) to develop a composite map at the country level. Compilation of state-level estimates showed 6.7 M ha salt affected soils in India, of which saline and sodic soil covered 2.9 and 3.7 M ha, respectively. Superimposing physiography, rainfall, temperature, agro-climatic zones and geology data, interactive database were generated to show spatial associations with salt affected soils.