On farm management of poor quality drainage water

In arid and semi-arid regions, effluent from subsurface drainage is often saline and in the absence of a natural outlet, its disposal is a serious environmental threat. Field studies were conducted for several years to utilize drainage water together with canal water for optimal crop production during the winter season. Three strategies were discussed for reuse of drainage water. Results indicated that drainage water of varying salinity levels can be used successfully for irrigating the winter crops either after dilution to suitable salinity level or in conjunction with canal water without undue yield reduction and soil degradation. Trials also revealed the benefits of irrigating with canal water during the initial stages including pre-plant irrigation. The drainage water volume problem can be eliminated by planning the operation of drainage system to leach the accumulated salts during the rainy season (kharif) when the drainage requirements for crops is high and to maintain shallow water-table for meeting the part of crop water requirements in the period of water scarcity. Monsoon induced salt leaching and ensuing crop establishment, however will depend on the total amount of monsoon rains. Use of drainage water for crop production will save the scarce canal water, reduce the disposal needs and associated environmental problems.