Abstract

                                Delineation of available macro and micronutrients was carried out by collecting 318 geo referenced surface soil samples from 53 villages in 14 blocks covering nine taluks of Tiruchirapalli district, Tamil Nadu using Global positioning system (GPS) by following multistage stratified random sampling approach. The soil samples were analyzed for 12 chemical parameters and georeferenced data were used for the preparation of soil fertility maps using GIS. Results from the analytical data of 318 soil samples revealed that a major per cent of the samples was neutral to alkaline, non-saline, low to high in OC, low in available N, medium in available P and medium to high in available K. With regard to available S and micronutrients, Zn is predominantly deficient; B is moderate to sufficient while S, Fe, Cu, and Mn were in sufficient status. Based on Nutrient Index Value, the over all fertility rating is medium OC, low, medium and high and very high N, P, K and S, respectively; marginal Zn, high Fe, Cu and B and very high Mn. Making use of the analytical data and GPS readings the thematic soil fertility maps were generated by krigging in Arc-GIS software version 9.3. The maps clearly revealed that, a major area of the district was alkaline, non-saline, medium in OC, low, medium and high in available N,P and K, respectively with regard to available S and micronutrients, Zn was predominantly deficient, B was moderate while S, Fe, Cu and Mn were in sufficient status.

Key words : GIS, Soil fertility, Thematic maps, Tiruchirapalli district.