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Submitted to: Handbook of Plant and Crop Stress
Publication Type: Book / Chapter Publication Acceptance Date: 6/30/2010 Publication Date: 7/31/2010 Citation: Suarez, D.L. 2010. Soil Salinization and Management Options for Sustainable Crop Production. Handbook of Plant and Crop Stress. Chapter 3 pp: 41-54. Interpretive Summary: Increasing demands on fresh water supplies means that irrigated agriculture in arid regions must use water more efficiently as well as develop strategies to use degraded waters for irrigation. Among the concerns when using degraded waters are elevated levels of salinity, sodium, pH and boron. This paper describes the impact of these factors on soil physical properties and provides revised guidelines for irrigation water with respect to sodicity and pH. Using the SWS computer model we also determined that existing guidelines for plant salt tolerance very significantly over-estimate the amount of leaching water required to avoid plant yield loss. These findings are consistent with field data on drip irrigation studies where little or no yield loss is observed with irrigation levels comparable to the crop water demand. Thus irrigation with more saline waters will not require extensive leaching and generation of large quantities of drainage water. This research is of interest to water quality specialists, irrigation managers, and water agencies. Technical Abstract: Irrigated acreage in arid regions of the world has recently stopped increasing and it will be difficult to even maintain existing levels of irrigation in these regions. At the same time the amount of salt affected soils in the world, continues to increase, with a major part being secondary salinization in irrigated lands. Since this salinization is caused primarily by over irrigation, more uniform irrigation application systems would allow for reductions in quantities of water applied, reducing leaching volumes, and paradoxically may reduce soil salinity, due to likely lowering of shallow water tables. Current guidelines indicate that irrigation with saline waters is not practical for most crops as it would require very large quantities of leaching water for salinity control in the root zone. SWS model simulations were made of salt distribution in the root zone and plant response to water uptake weighted salinity. These simulations confirm field data indicating that existing guidelines significantly overestimate water quantities needed for salinity control (leaching) in the root zone to avoid or minimize plant yield loss. The sodicity hazard associated with application of saline water has been generally overlooked, as irrigation with these waters does not adversely impact infiltration. These evaluations overlook the impact of even small quantities of rain on saline soils with elevated SAR, which has an adverse impact on physical properties of the soil surface. |
