In arid and semi-arid regions, effluent from subsurface drainage systems is often saline and during the dry season its disposal poses an environmental problem. A field experiment was conducted from 1989 to 1992 using saline drainage water (EC=10.5-15.0dS/m) together with fresh canal water (EC = 0.4 dS/m) for irrigation during the dry winter season. The aim was to find if crop production would still be feasible and soil salinity would not be increased unacceptably by this practice. The experimental crops were a winter crop, wheat, and pearl-millet and sorghum, the rainy season crops, grown on a sandy loam soil. All crops were given a pre-plant irrigation with fresh canal water. Subsequently, the wheat crop was irrigated four times with different sequences of saline drainage water and canal water. The rainy season crops received no further irrigation as they were rainfed. Taking the wheat yield obtained with fresh canal water as the potential value (100%), the mean relative yield of wheat irrigated with only saline drainage water was 74%. Substitution of canal water at first post-plant irrigation and applying thereafter only saline drainage water, increased the yield to 84%. Cyclic irrigations with canal and drainage water in different treatments resulted in yields of 88% to 94% of the potential. Pearl-millet and sorghum yields decreased significantly where 3 or 4 post-plant irrigations were applied with saline drainage water to previous wheat crop, but cyclic irrigations did not cause yield reduction. The high salinity and sodicity of the drainage water increased the soil salinity and sodicity in the soil profile during the winter season, but these hazards were eliminated by the sub-surface drainage system during the ensuing monsoon periods. The results obtained provide a promising option for the use of poor quality drainage water in conjunction with fresh ca-

The study was conducted in the summer season (April-May 2007). The fluoride concentration along with physico-chemical parameters in ground water samples was determined in various villages of Kadi tehsil at Mehsana district of Gujarat state (India), since in most of the villages it is the only source of drinking water. The fluoride concentrations in these villages varied from 0.94 to 2.81 mg/L (1.37+/-0.56) with highest fluoride level at Visalpur (2.08 mg/L) and lowest at Adaraj (0.91 mg/L). There was found a positive correlation of pH with fluoride and a negative relationship of fluoride with bicarbonate which is generally observed in deep ground water.

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In arid and semi-arid regions, effluent from subsurface drainage is often saline and in the absence of natural outlet, its disposal is a serious environmental threat. A field experiment was conducted on a sandy loam soil to evaluate the effects of conjunctive use of saline drainage water (EC iw = 7.2 -9.8 dS m 7 1 ; SAR = 8.4 -13.5) and non-saline canal water (EC iw = 0.3 -0.4; SAR = 0.6 -0.8) in different modes on soil salinity build-up, growth and yield of sunflower (Helianthus annuus L.) and succeeding sorghum (Sorghum bicolour L.). The results indicated that pre-plant irrigation with saline drainage water decreased the growth and yield of sunflower significantly. The effect was not significant when non-saline water was used for pre-plant irrigation. The mean relative grain yield of sunflower irrigated with only saline drainage water was 56.9%. Substitution of non-saline canal water for first two irrigations increased the yield to 87.2%. Alternate irrigations in different treatments resulted in yields of 65.8 to 81.9% of the potential. Sorghum fodder yield decreased significantly where all the irrigations were applied with saline drainage water to previous sunflower crop. Increased soil salinity and alkalinity hazards were eliminated by the subsurface drainage during the ensuing monsoon period.