Abstract

Geographical Information System (GIS) with the aid of CROPWAT 8.0 and SPAW programmes offers efficient way of modeling the crop water requirement and portraying spatially, yet to be tapped for agro-climatic studies. Viralimalai block, situated in the northwestern part of Pudukkottai District in Tamil Nadu is one the economically backward area and subject to drought often, where the crop water and irrigation requirement for each textural soil units have been assessed for groundnut (Arachis hypogaea), sorghum (Sorghum bicolor), and pearl millet (Pennisetum glaucum) which are the dominant dry crops of the block. The efficiency of rainfall is higher which favours groundnut and sorghum attributed by clay and clay loam structure of the soil. The rainfall efficiency is poor in loamy sand and sandy loam soil as for the groundnut and maize considered. Loamy sand areas are identified with excess irrigation requirement accounting with 260 mm for groundnut, 280 mm for sorghum and 116 mm for Pearl millet. The irrigation requirement is minimum and even not required over the areas under clay textured soil as for the crops under study.