Delineation of available macronutrients was carried out by randomly collecting geo referenced surface (0–0.15m) soil samples representing different soil units as per the soil map prepared on 1:50,000 scale from 1886 sites in Coimbatore district, Tamil Nadu using Global Positioning System (GPS). The soil samples were analysed for available macronutrients. The available N status ranged from 102 to 394 kg ha−1 while the available Pand K status varied from 5.30 to 75.10 and 102 to 789 kg ha−1 respectively. Analytical results and the GPS data were used for the preparation of thematic map showing spatial distribution of macronutrients status block wise in the district. Location of soil sampling sites of Coimbatore district were marked on base map on 1:50,000 scale prepared from State Revenue Maps and digitized using Arc-info GIS. The delineation study clearly indicated that the available N was found to be low in 86.41 percent of soils of Coimbatore district while phosphorus is medium status. Nearly 56.55 per cent of the surface soil of Coimbatore district was high in available K status.
Available Nitrogen, Phosphorus, Potassium, GPS, GIS, Thematic maps
