GIS-Based Soil Mapping of Nagapattinam District, Tamil Nadu, India: A Study on Sulphur Content and Associated Soil Properties

The importance of sulphur in agriculture is evident because plants require sulphur for the synthesis of essential amino acids, proteins, vitamins, and coenzymes and to activate certain enzymes. Advanced techniques like global positioning systems (GPS), geographic information systems (GIS) and precision agriculture facilitate soil secondary nutrient mapping, providing quantitative support for decision and policy-making to improve agricultural approaches for balanced nutrition. Thus, thematic maps help design appropriate strategies to enhance the productivity of crops. A study was carried out in the Nagapattinam district to assess sulphur status and soil properties, create a data bank, and prepare thematic maps. A total of 1631 geo-referenced surface soil samples covering 11 blocks in Nagapattinam district were collected randomly at 0-15 cm depth and analyzed for various soil properties, such as pH, electrical conductivity (EC), organic carbon (OC), free CaCO3. The overall soil reaction in the Nagapattinam district at different blocks was mainly neutral, with low soil salinity hazards. The data on organic carbon status in the soils was medium. The average free calcium carbonate status in the soils of different blocks revealed moderately calcareous. The average available sulphur was found to be in the range of 54.4 to 153 mg kg-1. Higher availability of sulphur with a combined average of 84.8 mg kg-1 was noticed in the soils of the entire district and could be attributed to the high organic carbon content and heavy texture of the soils.