Computerized Database of Salt-affected Soils in Peninsular India using Geographic Information System

Computerized database of salt-affected soils (SAS) was prepared for Andhra Pradesh, Karnataka, Tamil Nadu, Kerala and Orissa using Geographic Information System (GIS). The analogue maps of SAS on 1:250,000 scale were geo-referenced and digitized using ILWIS software. Thematic layers were developed for state/district boundaries, roads/railways, rivers/canals and settlements and overlaid to prepare the basemap. Superimposing polygons (spatial coverage) of SAS units and the basemap, the state map of salt-affected soils was prepared. These maps were integrated in GIS to generate a composite (master) database of salt-affected soils in peninsular region. The soil characteristics such as nature and degree of salinity/sodicity and its ground coverage were entered in attribute table and linked with the SAS polygons to develop a relational database. Superimposing the boundaries of agro-climatic regions (ACR) and agro-climatic zones (ACZ), the regional and zonal database of salt-affected soils was prepared. Two types of SAS such as saline (27%) and sodic (73%) were identified. The saline soils were distributed in coastal, deltaic and mangrove regions of Orissa (15%) and Kerala (2%) states. The sodic soils were located in Andhra Pradesh (20%), Tamil Nadu (37%) and Karnataka (15%) – primarily distributed in the peninsular and alluvial plains. Significant area (69%) was distributed in West Coast Plain and Ghat Region (ACR XI), followed by Southern Plateau and Hills Region (ACR X, 26%) and East Coast Plains and Hills Region (ACR XII, 4.5%). Digital overlay of SAS with landform and geology data showed spatial association of SAS with parent materials and landform.