Sustainable Management of Saline Waters and Salt-Affected Soils for Agriculture: Proceedings of the Second Bridging Workshop

Abstract

Irrigation plays an important role in crop production and agricultural development in arid and semi-arid regions. The area of irrigated land in these regions has expanded substantially, particularly in the second half of the twentieth century. However, further, the expansion will have to occur within the limits of annual renewable freshwater resources, which, in many places, have largely been allocated already to various water-use sectors. Competition among domestic, industrial, environmental, and agricultural sectors already exists and will inevitably increase. This will lead to a gradual decrease in freshwater allocation to agriculture. This phenomenon is expected to continue and intensify in arid regions in less developed countries that already have high population growth rates and significant environmental degradation. As an alternative to freshwater, water resources of marginal quality – such as saline water generated by agricultural drainage systems or pumped from saline aquifers – can be used to reduce the gap between demand and supply. Although saline water is already used in agriculture, its use without suitable soil-crop-irrigation management poses high risks of land degradation through the development of salinity, sodicity, ion-specific toxicity, and nutrient imbalance in soils. These conditions reduce crop productivity and limit crop choice. The use of saline water for agriculture is likely to increase with increasing water scarcity. It will be important to modify current soil, irrigation, and crop management practices to cope with the inevitable increases in soil salinity and sodicity. It will also be important to assess the future sustainability of using saline water, in regard to maintaining soil's physical properties and crop productivity. Clearly, there is a need to rethink the ways in which saline water is used for irrigation; and to develop appropriate technical and policy options for productive use of saline water in water-scarce countries.