Submitted to: Proceedings of the International Salinity Forum
Publication Type: Proceedings
Publication Acceptance Date: 2/2/2008
Publication Date: 3/30/2008
Publication URL: http://www.ars.usda.gov/SP2UserFiles/Place/53102000/pdf_pubs/P2280.pdf
Citation: Suarez, D.L. 2008. Irrigation salinity: The state of knowledge and emerging issues. Proceedings of the International Salinity Forum. Salinity, water and society - global issues, local action. In Adelaide, Australia, March 31 - April 3, 2008. pp. 1-4. Interpretive Summary: There is currently an unsustainable use of fresh water resources in arid and semi arid regions. It is currently projected that water demands will continue to increase, and when coupled with decreasing supplies, it is likely that there will be less available fresh water for irrigated agriculture. Recycled treated municipal waste water and irrigation drainage waters combined with supplies of available brackish water, are all valuable resources to sustain irrigated agriculture in arid regions. The issues of water quality including potentially toxic elements, ion imbalances, pathogens and contaminants will require new water quality criteria, prediction of long term effects, different management practices, and field monitoring. Plant breeders will need to develop varieties that reflect the water quality that will be available in the future, breeding for tolerance to the factors mentioned, salinity, toxic ions and ion imbalance. New management practices and development of suitable plant varieties are feasible to allow successful use of marginal waters for irrigation.
Technical Abstract: Current irrigation practices in arid and semi-arid regions are not sustainable. These regions are experiencing increasing population and development with increasing demands for limited fresh water for municipal and industrial use. In arid areas fresh water use is currently in excess of sustainable quantities, irrigated acreage is already declining in many regions, and soil salinization is increasing. Improvements in irrigation efficiency and leaching control are possible but provide only a partial solution to sustaining irrigation and its high crop production. Most regions have abundant quantities of low quality saline, drainage and sewage waters, most of which could potentially be used for irrigation, and will likely be a major source of irrigation water in the future. Use of these waters requires new strategies for water management including new knowledge of factors affecting infiltration and crop production and development of computer models that consider the numerous interactions, enabling evaluation of various practices. We need to develop alternative crops, and new varieties that are tolerant to salinity, ion imbalances and toxic elements. Water quality criteria currently reject waters that in some instances can be detrimental and without consideration that in many areas the water requirements can be met by a combination of rain, fresh water and saline water, thereby diminishing the salinity impact. Treated wastewaters have elevated pH, alkalinity, and sodium, relatively low Ca/Mg ratios, high concentrations of dissolved organic matter, all adverse to infiltration and soil structure, as well as ion imbalances and potentially toxic elements. Use of these waters may require periodic application of amendments and/or leaching, utilizing new knowledge about factors affecting infiltration and crop production. Environmental concerns about recycled water include plant uptake of toxic elements, pharmaceuticals, endocrine disrupters etc. as well as off-site impacts to discharge areas.