Strategies for managing saline/alkali waters for sustainable agricultural production in South Asia

Increasing the productivity of water and making sate use of poor quality waters in agriculture will play a vital role in easing competition for scarce water resources, prevention of environmental degradation and provision of food security. Driven by the pressure to produce more, even the saline and alkali waters are being increasingly diverted to irrigated agriculture. Development of salinity. sodicity and toxicity problems in soils not only reduces crop productivity and quality but also limit the choice of crops. There are two major approaches to improving and sustaining productivity in a saline environment: modifying the environment to quit the plant and modifying the plant to suit the environment, but the former has been tried more extensively. The available options are mediated through the management of crops/sequences, irrigation water, chemical/amendments and other cultural practices but all must be integrated as per the site specific needs and achieving higher yields on sustainable basis. Some important interventions include appropriate crop/variety selection, blending saline/alkali and fresh water to keep the resultant salinity below threshold, or their cyclic application by scheduling irrigation with salty water at less salt sensitive stages. At the farm/irrigation system level, policy measures like re-allocation of water to higher value crops and those with limited irrigation requirement, spatial re-allocation and transfer of water, adopting policies that favor development of water markets and adequate utilization of groundwater can help in improving water productivity in saline environments. The other viable options include salinity tolerant agro-forestry systems and bio-saline agriculture. Besides technological advances, peoples' participation and favorable water use and allocation policies need to be put in place for sustainable use of saline/alkali waters. (c) 2005 Elsevier B.V. All rights reserved.