Managing Saline Water for Irrigating Agricultural Crops

Concerted efforts at worldwide research centres under different agro-climates have yielded valuable concepts and viable technologies for the sustainable irrigation with saline waters. Tolerance limits to the use of saline waters stand established for appropriate selection of crops and their cultivars. Tolerances also vary considerably with soil type, rainfall, and crop growth stages. Providing for leaching requirement helps to control salinity in arid climates while in semi-arid areas, a part of salt balance is attained with rainwater. Benefits of frequent irrigation which also increase the salt loads can better be achieved with drip and sprinkler irrigation where depth of irrigation can be simultaneously controlled. Another management goal should be to encourage the utilization of both the carried over rainwater in soil profile and capillary fringe in shallow water-tables areas. Multi-location trials on appropriate use of saline and non-saline waters reveal the benefits of irrigating with non-saline canal water for pre-plant irrigation as well as during the initial stages. Cyclic uses show both operational and performance advantages over mixing the saline waters with canal water. Other cultural practices like furrow planting, increasing plant density, and post-seeding irrigation in crops like mustard, also prove useful. Soil structural problems may emerge when irrigation waters have SAR-saline water >15, Mg:Ca >3 and rich in silica. Thus use of amendments like gypsum is recommended for these soils. Integrated use on inorganic fertilizers and organic manures improves nutrient use efficiency while some of PGRs like thio-urea, salicylic acid have been shown to mitigate the effects of salinity.