Abstract

Thirty three bore wells were selected under different categories viz. Deep (>100m), Shallow (20 - 100m) and Filter points (<20m) covering the Fluvial land forms of Karaikal region where major cropping activities were undertaken. In about 90.9 per cent of the deep bore well samples, the EC ranged between 0.751 - 2.250 dSm-1. However, in around 35.7 and 50 per cent of the shallow and filter point bore well samples, it ranged between 2.251 - 5.000 dSm-1. Among the cationic composition, Na+ dominated in the deep and shallow bore wells while Na to other cation ratio was narrower in the filter points. Similarly, Cl-1 and HCO3 - among the anionic composition dominated in all the categories of bore wells. On the basis of classification of Residual Sodium carbonate (RSC) concept, around 73, 69 and 100 per cent of deep, shallow and filter point bore wells, respectively were safe to medium in safe for irrigation to agricultural crops. The geological formation of the deeper bore well could able to yield a suitable and required quantity of water for irrigation but the marine beds of pleocene period in between the sand stone and surface of soil was blocked from mixing with the bore well water

Keywords: Bore wells, cationic composition, irrigation