Submitted to: Plant and Soil Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 2/1/2008
Publication Date: 2/4/2008
Citation: Suarez, D.L. 2008. Modern concepts in the management of saline soils and irrigation supplies. California Plant and Soil Conference Proceedings, held in Visalia, CA. Feb. 5-6, 2008, pp: 58-61. Interpretive Summary: The scarcity of high quality water in the southwestern U.S. threatens the sustainability of irrigated agriculture. Use of lower quality waters for irrigation is feasible but requires a more detailed evaluation of water quality and its impacts on crop production and soil properties. Rather than ranking water as suitable or unsuitable for irrigation, it is suggested that we consider the interactions of crop, soils, climate, water and management for a site- specific evaluation. Use of these combined criteria in the framework of a numerical model will enable evaluation of the feasibility of using low quality waters for irrigation on a case by case basis.
Technical Abstract: Existing water quality guidelines and recommendations for salinity management are based on early research conducted by USDA-ARS Salinity Laboratory and University of California researchers. These were recommendations established at a time when irrigation projects were under development and there was abundant high quality water for irrigation. At the present time there is a shortage of high quality water in the southwestern U.S. and irrigated agricultural acreage is declining. Increasing demands on our fresh water supplies means that irrigated agriculture will need to look to alternative sources of water, including reuse of drainage water, treated municipal and industrial waste waters, and brackish ground waters. These waters are invariably higher in salinity than the currently utilized fresh waters, with the added salinity often being primarily sodium and chloride. These conditions require renewed attention to salinity management and current recommendations. Current water quality criteria were developed as simple criteria designed to avoid problems under most conditions. Rather than classification of waters as suitable and unsuitable it is more useful to develop predictive relationships that describe how certain water quality parameters impact crop and soil responses. Once the site specific conditions are considered, then we should evaluate management practices that allow for sustained use of the water, and then consider if the results are economically beneficial. Based on new research we propose a modification of the existing guidelines, the major changes being consideration of the impact of rain on soil stability and impact of irrigation water pH on sodicity hazard.