Soil Salinization

by

Pichu Rengasamy

• LAST REVIEWED: 24 March 2021
• LAST MODIFIED: 25 November 2014
• DOI: 10.1093/obo/9780199363445-0008

Introduction

Soils are made up of inorganic and organic compounds inclusive of living organisms. Soil salinization is the accumulation of water-soluble salts within soil layers above a certain level that adversely affects crop production, environmental health, and economic welfare. Soil salinity is described and characterized in terms of the concentration and composition of the soluble salts. Even though soluble salts are inherent in all soils, there are many processes that can contribute to the build-up of salts in a given soil layer. Weathering of soil minerals, salts added through rain, agronomic practices such as fertilizer and pesticide application, saline groundwater intrusion with water table fluctuations, irrigation with saline water sourced from bore, recycled or waste waters, dumping of industrial and municipal wastes into soils, and other soil conditions leading to reduced leaching of salts from the soil layer—all can lead to soil salinization. Seawater intrusion onto land when sea levels increase can deposit a large amount of salts in soils of coastal lands. The particular processes contributing salt, combined with the influence of other climatic, hydrological, and landscape features and the effects of human activities, farming practices, and plant interactions, determine where salinization occurs. Worldwide, more than 800 million hectares of land are estimated to be salt-affected, covering a range of soils defined as saline, saline-sodic and sodic in every climatic zone in every continent except Antarctica. All soil types with diverse morphological, physical, chemical, and biological properties may be affected by salinization. Generally, salt-affected soils are predominant in arid and semi-arid regions.

Processes of Soil Salinization

Soil salinization is normally classified as “primary” and “secondary” salinity, based on whether salt accumulates by natural phenomena or as a consequence of the management of natural resources. There are three major types of salinity based on soil and groundwater processes found all over the world. They are: (1) groundwater-associated salinity, or fluctuations in groundwater (usually saline) leading to water and salt discharge on soil surface layers; (2) non-groundwater-associated salinity, or poor hydraulic properties of soil layers (commonly found in sodic soils) resulting in reduced leaching; and (3) irrigation-associated salinity, where salts introduced by irrigation water are stored in soil layers because of insufficient leaching. During these processes, the secondary salinization is usually accelerated or enhanced by several human activities. With the introduction of agriculture and clearance of perennial native vegetation, the equilibrium levels of the water tables change. In low-lying regions, where water tables are shallower, more unused water by crops and pastures, with salt, leaks from the upper soil layers and raises the levels of groundwater. As the groundwater approaches soil surface, salt accumulates, aided by evaporation. In coastal aquifers, the salt water from the sea flows inland into freshwater aquifers, causing saltwater intrusion, a result of the density difference caused by salinity levels between seawater and freshwater, as defined by the Ghyben-Herzberg principle. This process is enhanced by the extraction of fresh groundwater. In irrigated regions, the quantity and quality of salt in irrigation water leads to the accumulation of salts when drainage conditions do not meet leaching requirements. Salt deposition from wind-blown materials from desiccated lakes and seepage from urban infrastructure also lead to soil salinization.

• Artzy, M., and D. Hillel. 1988. A defense of the theory of progressive soil salinization in ancient southern Mesopotamia. Geoarcheology 3:235–238.

  DOI: 10.1002/gea.3340030306Save Citation »Export Citation » Share Citation »

  Artzy and Hillel 1988 is a paper that gives an explanation of the fundamental processes of soil salinization and degradation induced by irrigation of poorly drained river valleys in arid regions, and it explains why these processes were practically uncontrollable under the circumstances of ancient southern Mesopotamia.

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• Beresford, Q., H. Bekle, H. Phillips, and J. Mulcock. 2001. The salinity crisis: Landscapes, communities and politics. Crawley: Univ. of Western Australia Press.

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  Beresford, et al. 2001 is a paper that deals with the secondary salinization and the impact of stream salinization in relation to landscapes in Western Australia and the role of communities and politics.

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• Ghassemi, F., A. J. Jakeman, and H. A. Nix. 1995. Salinization of land and water resources: Human causes, extent, management and case studies. Sydney: Univ. of New South Wales Press Ltd.

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  Ghassemi, et al. 1995 is a book that reviews the global and regional extent of salinization of land and water resources. The authors describe salinity problems in thirteen selected countries, including Argentina, Australia, China, Egypt, India, Iran, Pakistan, South Africa, Thailand, and the United States, as well as processes of salinization in land and water resources and management strategies.

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• Hillel, D. 2005. Soil salinity: Historical and contemporary perspectives. Proceedings of the International Salinity Forum, Riverside, California, April 25–27, 2005, 235–240. Riverside, CA: Water Science and Policy Center.

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  Hillel 2005 is a paper that discusses historical and contemporary perspectives on soil salinity. This paper is useful to understand the general nature of salinization through generations.

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• Jacobsen, T., and R. M. Adams. 1958. Salt and silt in ancient Mesopotamian agriculture. Science 128:1252.

  DOI: 10.1126/science.128.3334.1251Save Citation »Export Citation » Share Citation »

  Jacobsen and Adams 1958 is a short paper which gives an account of salinization problems in an ancient civilization. Shows that the problem of salinity is not new, and how salinization can destroy an entire civilization.

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• Rengasamy, P. 2006. World salinization with emphasis on Australia. Journal of Experimental Botany 57:1017–1023.

  DOI: 10.1093/jxb/erj108Save Citation »Export Citation » Share Citation »

  Rengasamy 2006 is a paper that reviews the different types of salinity found globally, and specifically distinguishes the transient salinity not associated with groundwater. This paper also examines the subsoil constraints associated with salinization of Australian soils and the soil processes that dictate the edaphic environment important for root functions.

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• Salama, R. B., C. J. Otto, and R. W. Fitzpatrick. 1999. Contributions of groundwater conditions to soil and water salinization. Hydrogeology Journal 7:46–64.

  DOI: 10.1007/s100400050179Save Citation »Export Citation » Share Citation »

  Salama, et al. 1999 is a paper that explains salinization by two main chemical models developed by the authors: weathering and deposition. Provides details on case studies at a small catchment scale in South and Western Australia. The authors compare the situations in Australia, the United States, and Sudan.

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• Schofield, R., D. S. G. Thomas, and M. J. Kirkby. 2001. Causal processes of soil salinization in Tunisia, Spain and Hungary. Land Degradation & Development 12:163–181.

  DOI: 10.1002/ldr.446Save Citation »Export Citation » Share Citation »

  Schofield, et al. 2001 is a paper that presents the results from the study of three contrasting salt-affected landscapes. Irrigation-oriented salinity in Spain, the natural occurrence of salt-affected soil in Hungary, and the catenary relationship to salinity in Tunisia are discussed to demonstrate various causal processes of soil salinization.

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• Vengosh, A. 2003. Salinization and saline environments. Treatise on Geochemistry 9:333–365.

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  Vengosh 2003 is an essay which recognizes that salinization is a global environmental phenomenon affecting many aspects of human life. The author explains in detail river salinization, lake salinization, groundwater salinization, salinization of dryland environment, and anthropogenic salinization. He also elucidates the sources of salinity.

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Assessment of Soil Salinization

Generally, soil salinity is assessed by measuring the electrical conductivity (EC) of soil solutions prepared in the laboratory, which is done by mixing soils with water in different proportions, such as 1:5 or 1:2 soil-water mixtures, or it may be extracted from the water-saturated paste of a soil. The extraction of soil water under field conditions by using vacuum pumps is also used to measure EC. Electromagnetic induction methods, aerial photographs, satellite and airborne multiple sensors, microwave sensors, video imagery, airborne geophysics, and hyperspectral sensors are used for surveying and mapping salinity in large areas or regions.

• Amezketa, E. 2006. An integrated methodology for assessing soil salinization, a pre-condition for land desertification. Journal of Arid Environments 67:594–606.

  DOI: 10.1016/j.jaridenv.2006.03.010Save Citation »Export Citation » Share Citation »

  Amezketa 2006 is a paper that shows the usefulness of an integrated methodology involving a hand-held electromagnetic sensor and the ESAP software for assessing, predicting, and mapping soil salinity

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• Metternicht, G. I., and J. A. Zinck. 2003. Remote sensing of soil salinity: Potentials and constraints. Remote Sensing of Environment 85:1–20.

  DOI: 10.1016/S0034-4257(02)00188-8Save Citation »Export Citation » Share Citation »

  Metternicht and Zinck 2003 is a review paper about various sensors (aerial photographs, satellite and airborne multispectral sensors, microwave sensors, video imagery, airborne geophysics, hyperspectral sensors, and electromagnetic induction meters) and approaches used for remote identification and mapping of salt-affected areas.

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• Metternicht, G. I., and J. A. Zinck. eds. 2009. Remote sensing of soil salinization: Impact on land management. New York: CRC Press.

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  Metternicht and Zinck 2009 is a recent book which discusses not only remote sensing of soil salinization, but also general aspects of soil salinization, spectral behavior of salt types, and soil management. See p. 377.

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• Rhoades, J. D. 1993. Electrical conductivity methods for measuring and mapping soil salinity. In Advances in agronomy. Vol. 49. Edited by L. S. Donald, 201–251. San Diego, CA: Academic Press.

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  Rhoades 1993 is an useful chapter describing practical methodology for measuring electrical conductivity in the laboratory to monitor and map soil salinity.

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• Schofield, R. V., and M. J. Kirby. 2003. Application of salinization indicators and initial development of potential global soil salinization scenario under climatic change. Global Biogeochemical Cycles 17:1078.

  DOI: 10.1029/2002GB001935Save Citation »Export Citation » Share Citation »

  Schofield and Kirby 2003 is a paper which investigates salt-affected soils on a global scale through spatial modeling with a geographical information system (GIS). The paper derives salinity indicators from global data sets and compares them to independent maps of salt-affected areas.

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• Tanji, K. K., and W. W. Wallender, eds. 2012. Agricultural salinity assessment and management. 2d ed. ASCE Manuals and Reports on Engineering Practice 71. Reston, VA: American Society of Civil Engineers.

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  Tanji and Wallender 2012 is a comprehensive book dealing with all aspects of salinity assessment and management and explaining the basic principles of chemistry and physics associated with salt-affected soils. Available as an e-book.

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Distribution and Extent of Salt-Affected Soils

The global distribution of salt-affected soils is estimated to be around 830 million hectares extending over all the continents, including Africa, Asia, Australasia, and the Americas. The exact location and distribution of salinized soils have been studied in varying degrees of detail. Different systems of classification and grouping are employed in individual countries. In addition, the various maps have not been prepared on a uniform scale. In many cases there is no clear distinction between “saline” and “sodic” soils, both of which are affected by soil salinization, but which have different soil processes and mechanisms that affect plant growth.

• Isbell, R. F., R. C. Reeve, and J. T. Hutton. 1983. Salt and Sodicity. In Soils, an Australian viewpoint. Edited by the Commonwealth Scientific and Industrial Research Organization, 107–118. Melbourne, Australia: Division of Soil, CSIRO.

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  Isbell, et al. 1983 is a comprehensive review of saline and sodic soils of Australia, including the distribution and extent of salt-affected soils in Australia.

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• Jasonsmith, J. F., B. C. T. Macdonald, D. C. McPhail, et al. 2011. Salinisation processes in a sub-catchment of Wybong Creek, Hunter Valley, Australia. Australian Journal of Earth Sciences 58:177–193.

  DOI: 10.1080/08120099.2011.543152Save Citation »Export Citation » Share Citation »

  Jasonsmith, et al. 2011 is a paper that deals with salinization in the Hunter Valley, Australia, and particularly analyzes the data from the site of Wybong Creek.

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• Martinez-Beltran, J., and C. L. Manzur. 2005. Overview of salinity problems in the world and FAO strategies to address the problem. In Proceedings of the International Salinity Forum, Riverside, California, April 25–27, 2005, 311–313. Riverside, CA: Water Science and Policy Center.

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  Martinez-Beltran and Manzur 2005 is an overview of world perspective of salinity problems, the global extent of salinity, and the strategies developed by FAO to solve the problems in different countries.

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• Northcote, K. H., and J. K. M. Skene. 1972. Australian soils with saline and sodic properties. Melbourne, Australia: Commonwealth Scientific and Industrial Research Organisation.

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  Northcote and Skene 1972 is the first report from Australian soil survey efforts to identify different categories of salt-affected soils and their area. This highly quoted publication also contains a map of salt-affected regions in Australia.

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• Nosetto, M. D., A. M. Acosta, D. H. Jayawickreme, S. I. Ballesteros, R. B. Jackson, and E. C. Jobaggy. 2013. Land-use and topography shape soil and groundwater salinity in central Argentina. Agricultural Water Management 129:120–129.

  DOI: 10.1016/j.agwat.2013.07.017Save Citation »Export Citation » Share Citation »

  Nosetto, et al. 2013 is a paper that quantifies the response of salt accumulation to the interactive effects of topography (lowland-upland gradients) and vegetation (annual crops, tree plantations, native grasslands) across a sub-humid sedimentary landscape in the Inland Pampas of Argentina.

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• Szabolcs, I. 1989. Salt-Affected Soils. Boca Raton, FL: CRC Press.

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  Szabolcs 1989 is a book which is highly quoted for referencing the distribution of salt-affected soils around the world. The author has written several books on this topic, and this one is more comprehensive than the others.

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• Thomas, D. S. G., and N. J. Middleton. 1993. Salinization: New perspectives on a major desertification issue. Journal of Arid Environments 24:95–105.

  DOI: 10.1006/jare.1993.1008Save Citation »Export Citation » Share Citation »

  Thomas and Middleton 1993 is a paper that considers the soil salinization as a significant component of desertification processes in the world’s dry lands. Also considers the nature of salinization processes and previous estimates, using the case of Africa, in particular.

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• Toth, G., L. Montanarella, and E. Rusco, eds. 2008. Threats to soil quality in Europe. JRC Scientific and Technical Reports. Luxembourg: European Commission.

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  Toth, et al. 2008 is a report dealing with the soils in Europe and the salinization of the European soils. An updated map of the salt-affected soils in the European Union is included.

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Salt-Affected Soils under Irrigation

Irrigation water is a major source of salts leading to soil salinization. The quality of irrigation water, its reaction with soil components affecting soil structural behavior, the soil conditions affecting the accumulation and removal of salts, the provision of drainage to maintain salt balance, and the consequent impact on agricultural production are important areas of research worldwide.

• Ali, M. H. 2011. Drainage of agricultural lands. In Practices of irrigation and on-farm water management. Vol. 2. By M. H. Ali, 327–378. New York: Springer.

  DOI: 10.1007/978-1-4419-7637-6_9Save Citation »Export Citation » Share Citation »

  Ali 2011 is a chapter that deals with the drainage of agricultural lands under irrigation, with particular attention given to salinity. The author explains the physics of drainage, theory of water movement, designs of drainage systems, and models for drainage design.

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• Bond, W., and C. Smith. 2006. Environmental implication of reclaimed water use for irrigated agriculture. In Growing crops with reclaimed wastewater. Edited by D. Stevens, 171–178. Collingwood, Australia: CSIRO.

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  Bond and Smith 2006 is a chapter that analyses the effects of using reclaimed water for irrigation on environmental health and agricultural production.

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• Kovda, V. A., Robert M. Hagan, and C. van den Berg. 1973. Irrigation, drainage and salinity: An international source book. London: Hutchinson.

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  Kovda 1973 is a source book on all aspects of irrigation, drainage, and salinity, covering case studies all over the world. The chapters on water and salt balances, soils in relation to salinity, irrigation and drainage, and chemistry of saline and alkali soils of arid zones contain important details.

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• Rengasamy, P., and K. A. Olsson. 1993. Irrigation and sodicity. Australian Journal of Soil Research 31:821–837.

  DOI: 10.1071/SR9930821Save Citation »Export Citation » Share Citation »

  Rengasamy and Olsson 1993 is a paper that deals with the mechanism involved in the accumulation of sodium in soils irrigated with poor-quality water. This paper also explains the role of leaching fraction dictated by soil management in the adsorption of sodium.

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• Rietz, D. N., and R. J. Haynes. 2003. Effects of irrigation-induced salinity and sodicity on soil microbial activity. Soil Biology & Biochemistry 35:845–854.

  DOI: 10.1016/S0038-0717(03)00125-1Save Citation »Export Citation » Share Citation »

  Rietz and Haynes 2003 is a paper that discusses the changes in soil microbial and biochemical properties induced by chemical changes occurring in saline and sodic conditions, particularly in irrigated soils. The increasing salinity and sodicity result in a progressively smaller, more stressed microbial community that is less metabolically efficient.

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• Saysel, A. K., and Y. Barlas. 2001. A dynamic model of salinization on irrigated lands. Ecological Modeling 139:177–199.

  DOI: 10.1016/S0304-3800(01)00242-3Save Citation »Export Citation » Share Citation »

  Saysel and Barlas 2001 is a paper that presents a dynamic simulation model of salt accumulation on irrigated lands. The model is a systemic one in the sense that it integrates four major subprocesses of rootzone salinization: irrigation, drainage, groundwater discharge, and groundwater intrusion.

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• Shainberg, I., and J. Shalhevet, eds. 1984. Soil Salinity under irrigation: Processes and management. Ecological Studies 51. Berlin and New York: Springer-Verlag.

  DOI: 10.1007/978-3-642-69836-1_3Save Citation »Export Citation » Share Citation »

  Shainberg and Shalhevet 2014 is a book that deals with all aspects of irrigation-induced salinity. This is a recommended reading to understand the principles involved in salinization under irrigation.

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Sodic Soils

Sodium salts such as sodium chloride and sodium carbonate are the major components of salinity in many salt-affected regions in the world. As a result, soil particles, particularly the clay fraction, adsorbs and retains sodium through cation exchange reactions. Saline-sodic soils become sodic when nonadsorbed salts are leached and subsequently degrade physical properties. Then again, sodic soils allow accumulation of salts and gradually becomes saline-sodic soils. The formation of sodic and saline-sodic soils is also influenced by climatic and landscape features.

• Bhargava, G. P., D. K. Pal, B. S. Kapoor, and S. C. Goswami. 1981. Characteristics and genesis of some sodic soils in the Indo-Gangetic alluvial plains of Haryana and Uttar Pradesh. Journal of the Indian Society of Soil Science 29:61–70.

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  Bhargava, et al. 1981 is a paper that deals with the formation of sodic soils in the Indo-Gangetic plains in northern India, detailing the weathering of parent materials and the topography responsible for the accumulation of sodium in different horizons.

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• Brady, N. C., and R. R. Weil. 2008. The nature and properties of soils. 14th ed. Upper Saddle River, NJ: Pearson Prentice Hall.

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  Brady and Weil 2008 is a text book on soil science and deals with the basic principles involved in the formation, properties, and management of sodic soils. It is recommended for graduate students and beginners to understand the fundamental principles related to sodic soils.

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• Bresler, E., B. L. McNeal, and D. L. Carter. 1982. Saline and sodic soils: Principles, dynamics, modelling. Berlin and New York: Springer-Verlag.

  DOI: 10.1007/978-3-642-68324-4Save Citation »Export Citation » Share Citation »

  Bresler, et al. 1982 is a highly used text book dealing with the physics and chemistry of salt-affected soils, particularly sodic soils. This book is very useful in understanding the different processes occurring in sodic soils

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• Sumner, M. E. 1993. Sodic soils: New perspectives. Australian Journal of Soil Research 31:683–750.

  DOI: 10.1071/SR9930683Save Citation »Export Citation » Share Citation »

  Sumner 1993 is paper that discusses the different global systems defining a sodic soil on the basis of exchangeable sodium percentage (ESP) and providing new perspectives on sodic soils on the basis of both ESP and electrolyte concentration, both of which affect sodic soil properties.

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• Sumner, M. E., and R. Naidu, eds. 1998. Sodic soils: Distribution, properties, management, and environmental consequences. New York: Oxford Univ. Press.

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  Sumner and Naidu 1998 is a comprehensive book on sodic soils, with various chapters dealing with all aspects of sodic soils, including the distribution of sodic soils all over the world, concepts on clay dispersion, nutritional constraints, the influence of organic matter, environmental consequences, soil physical factors, soil erosion, and soil management. This resource book has a number of useful references.

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• United States Salinity Laboratory. 1954. Diagnosis and improvement of saline and alkali soils. United States Salinity Laboratory Handbook 60. Washington, DC: US Dept. of Agriculture.

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  United States Salinity Laboratory 1954 is a book by the effort of the United States Salinity Laboratory staff that is highly referred to all over the world. This book originally introduced the concept of SAR (sodium adsorption ratio) and the methodology given in the book is the basis of research on saline and sodic (alkali) soils worldwide.

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Soil Processes Affecting Crop Production in Salinized Soils

The composition of salts dictates the nature and amount of cations and anions found in soil solution, which influence many soil phenomena, including soil physical conditions and chemical reactions; hence there are different categories of salt-affected soils. These categories generally determine the possible mechanisms of impact on plant growth through the effects on soil structure, osmotic potential, ion toxicity, or ion imbalance. In actual field conditions, the interactions between root-zone environments and plant responses to salinity are complicated by many soil processes, such as soil water dynamics, soil structural stability, solubility of salts in relation to pH and pE, and nutrient and water movement in soil. To be successful in the management of salinized soils and improvement of crop production, it is important that soil processes are considered in the evaluation of salt tolerance of plants and the activities related to plant development to adapt to saline lands.

• Barrett-Lennard, E. G. 2003. The interaction between waterlogging and salinity in higher plants: Causes, consequences and implications. Plant and Soil 253:35–54.

  DOI: 10.1023/A:1024574622669Save Citation »Export Citation » Share Citation »

  Barrett-Lennard 2003 is a paper that reviews a range of studies under controlled conditions, focusing on the effects of the interaction between waterlogging (hypoxia) and salinity on the ion relations, growth, and survival of higher plants, and argues that these interactions should be considered for saltland management, and also for the selection and breeding of plants adapted to saltland.

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• Bernstein, L. 1975. Effects of salinity and sodicity on plant growth. Annual Review of Phytopathol 13:295–312.

  DOI: 10.1146/annurev.py.13.090175.001455Save Citation »Export Citation » Share Citation »

  Bernstein 1975 is a paper in which the author explains the differences between salinity and sodicity in plant responses to these conditions. Also describes the mechanisms affecting plant growth under saline or sodic conditions, with a brief account of managing theses soils.

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• Dyer, C. L., P. M. Kopittke, A. R. Sheldon, and N. W. Menzies. 2008. Influence of soil moisture content on soil solution composition. Soil Science Society of America Journal 72:355–361.

  DOI: 10.2136/sssaj2007.0124Save Citation »Export Citation » Share Citation »

  Dyer, et al. 2008 is a paper that explains the importance of the soil solution to plant growth, and the influence of soil water content on the composition of the soil solution. The results in this paper demonstrate that changes in soil solution ionic strength and composition cannot be readily predicted without understanding the soil’s surface charge and exchange behavior.

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• Rengasamy, P. 2010. Soil processes affecting crop production in salt-affected soils. Functional Plant Biology 37:613–620.

  DOI: 10.1071/FP09249Save Citation »Export Citation » Share Citation »

  Rengasamy 2010 is a review that deals with the soil process in the field that determines the plant responses to increased osmotic pressure or specific ion concentrations. The author concludes that soil water dynamics, soil structural stability, solubility of compounds in relation to pH and pE, and water movement are all important in the development of plants tolerant to salinity.

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• Rengasamy, P. 2013. Salt-affected soils: Sustainable agriculture. In Encyclopedia of environmental management. Edited by E. J. orgensen, 2349–2356. New York: Taylor & Francis.

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  Rengasamy 2013 is a chapter that describes twelve categories of salt-affected soils, based on soil solution chemistry and the mechanisms by which plant growth are affected in each category. The author advocates three ways of managing saline soils: prevention of salt accumulation, removal of salts in the root zone, and adaptation to saline environment by growing appropriate salt-tolerant crops.

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Plant Factors in Adapting to Salinized Soils

Crop growth responds to salinity in two phases: a continuous osmotic phase that inhibits the water uptake by plants due to the osmotic pressure of saline soil solution lowering its potential energy (water always moving from a higher to lower potential energy levels); and a slower ionic phase in which the accumulation of specific ions in the plant, over a period of time, leads to ion toxicity or ion imbalance. Elucidation of these mechanisms and the development of plants tolerant to salinity are the focus of plant scientists involved in either conventional plant breeding or genetic engineering.

• Ashraf, M. 2004. Some important physiological selection criteria for salt tolerance in plants. Flora 199:361–376.

  DOI: 10.1078/0367-2530-00165Save Citation »Export Citation » Share Citation »

  Ashraf 2004 is a paper that reviews the major adaptive components of salt tolerance, such as osmotic adjustment, photosynthesis, and water and ion relations, in detail. The author emphasizes that it is most meaningful if physiological and biochemical indicators for individual species are determined, rather than generic indicators.

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• Chinnusamy, V., A. Jagendorf, and J.-K. Zhu. 2005. Understanding and improving salt tolerance in plants. Crop Science 45:437–448.

  DOI: 10.2135/cropsci2005.0437Save Citation »Export Citation » Share Citation »

  Chinnusamy, et al. 2005 is a paper in which the authors point out that understanding the molecular basis of salt-stress signaling and tolerance mechanisms is essential for breeding and genetic engineering, detailing cellular ion homeostasis, osmotic homeostasis, stress damage control, and repair under salt stress, and their exploitation for genetic engineering of salt-tolerant crop plants.

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• Flowers, T. J., P. F. Troke, and A. R. Yeo. 1977. Mechanism of salt tolerance in halophytes. Annual Review of Plant Physiology 28:89–121.

  DOI: 10.1146/annurev.pp.28.060177.000513Save Citation »Export Citation » Share Citation »

  Flowers, et al. 1977 is a highly quoted paper critically reviewing different mechanisms of salt tolerance in halophytes. This paper is of historical importance for researchers on the salt tolerance of plants.

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• Greenway, H., and R. Munns. 1980. Mechanisms of salt tolerance in non-halophytes. Annual Review of Plant Physiology 31:149–190.

  DOI: 10.1146/annurev.pp.31.060180.001053Save Citation »Export Citation » Share Citation »

  Greenway and Munns 1980 is a review on the mechanisms of salt tolerance in non-halophytes while the previous paper is on halophytes. In this highly cited and historically important paper, the authors focus on sodium-calcium interactions, ion excess, and water deficit.

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• Javid, M., M. Nicolas, and R. Ford. 2011. Current knowledge in physiological and genetic mechanisms underpinning tolerances to alkaline and saline subsoil constraints of broad acre cropping in dryland regions. In Abiotic stress in plants: Mechanisms and adaptation. Edited by A. Shanker and B. Venkateswarlupp, 193–214. Rijeka, Croatia: InTech.

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  Javid, et al. 2011 is a review on multiple subsoil constraints in salinized soils. While salt-tolerance mechanisms are discussed in relation to salinity alone by many researchers, these authors review the current knowledge in physiological and genetic mechanisms under multiple constraints, including salinity.

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• Munns, R., and M. Tester. 2008. Mechanisms of salinity tolerance. Annual Review of Plant Biology 59:651–681.

  DOI: 10.1146/annurev.arplant.59.032607.092911Save Citation »Export Citation » Share Citation »

  Munns and Tester 2008 is a recent review on the physiological and molecular mechanisms of tolerance to osmotic and ionic components of salinity stress at the cellular, organ, and whole-plant levels. The authors conclude that molecular genetics and functional genomics provide a new opportunity to synthesize molecular and physiological knowledge to improve salinity tolerance of plants.

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• Tavakkoli, E. 2011. Limitations to yield in saline-sodic soils: Quantification of the osmotic and ionic regulations that affect the growth of crops under salinity stress. PhD diss., Univ. of Adelaide.

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  Tavakkoli 2011 is a thesis that gives a comprehensive review of the literature related to the salt tolerance of crops, and of many experimental results quantifying the osmotic and ionic regulations in relation to the salt tolerance of barley varieties.

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Managing Salinized Soils

Successful utilization of salinized soils involves appropriate soil management and increasing agricultural production using improved plants to tolerate salinity and other associated abiotic stress. Development of plants by genetic modification to tolerate different levels of salinity is in progress and promises useful agricultural production in salinized soils. Each category of salinized soil will require a specific strategy, depending on how root zone processes and plant interactions are affected by soil solution composition. The plan of action to resolve the problems associated with soil salinization should focus on prevention of salt accumulation, removal of accumulated salts, and adaptation to a saline environment. Saline agriculture, a combination of several methods, is a new concept aimed at using salinized soils for improved economic returns.

• Abrol, I. P., J. S. P. Yadav, and F. I. Massoud. 1988. Salt-affected soils and their management. FAO Soils Bulletin 39. Rome: Food and Agriculture Organization of the United Nations.

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  Abrol, et al. 1988 is a book that deals with the origin, classification, and distribution of salt-affected soils. Details are given on the management of saline and sodic soils, particularly in dryland regions. The authors discuss water quality and crop production, as well as socioeconomic considerations in reclamation strategies.

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• Ali, M. H. 2011. Management of salt-affected soils. In Practices of irrigation and on-farm water management. Vol. 2. Edited by M. H. Ali, 271–325. New York: Springer.

  DOI: 10.1007/978-1-4419-7637-6_8Save Citation »Export Citation » Share Citation »

  Ali 2011 is a chapter that details the development of soil salinity and sodicity and their diagnosis, the management of saline and sodic soils, and amelioration techniques for sodic and saline-sodic soils. Also discusses models and tools for the management of salt-affected soils.

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• Ashraf, M., H. R. Athar, P. J. C. Harris, and T. R. Kwon. 2008. Some prospective strategies for improving crop salt tolerance. Advances in Agronomy 97:46–110.

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  Ashraf, et al. 2008 is a comprehensive review dealing with the various approaches in the genetic engineering of agricultural crops that can be used for managing salinized soils.

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• Gupta, R. K., and I. P. Abrol. 1990. Salt-affected soils: Their reclamation and management for crop production. Advances in Soil Science 11:223–288.

  DOI: 10.1007/978-1-4612-3322-0_7Save Citation »Export Citation » Share Citation »

  Gupta and Abrol 1990 is a book that explains the relative significance of the source of salinization and, in particular, the contribution of irrigation water. Also discusses the formation of “alkali” soils with high pH, including their properties and reclamation strategies.

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• Horneck, D. A., J. W. Ellsworth, B. G. Hopkins, D. M. Sullivan, and R. G. Stevens. 2007. Managing salt-affected soils for crop production. PNW 601-E. Corvalis, WA: Pacific Northwest Extension.

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  Horneck, et al. 2007 is an extension publication designed to help land managers evaluate the kind and amount of salts present in soils and to select management alternatives. It describes the soil tests commonly used in evaluating salt-affected soils in the western United States, and gives general guidelines for test interpretation.

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• Jayawardane, N. S., and K. Y. Chan. 1994. The management of soil physical properties limiting crop production in Australian sodic soils: A review. Australian Journal of Soil Research 32:13–44.

  DOI: 10.1071/SR9940013Save Citation »Export Citation » Share Citation »

  Jayawardane and Chan 1994 is a paper that describes the physical properties affected by soil sodicity in relation to crop production in Australia, and also reviews the management strategies using different techniques and amendments such as gypsum.

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• Qadir, M., J. D. Oster, S. Schubert, A. D. Noble, and K. L. Shrawart. 2007. Phytoremediation of sodic and saline-sodic soils. Advances in Agronomy 96:197–247.

  DOI: 10.1016/S0065-2113(07)96006-XSave Citation »Export Citation » Share Citation »

  Qadir, et al. 2007 is a review that advocates for the phytoremediation by growing selected plants. The authors conclude that success in this strategy requires a greater understanding of the processes fostering phytoremediation, the potential of plant species to withstand ambient salinity and sodicity levels, and the market economy.

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• Rozema, J., and T. Flowers. 2008. Crops for a salinized world. Science 322:1478–1480.

  DOI: 10.1126/science.1168572Save Citation »Export Citation » Share Citation »

  Rozema and Flowers 2008 is a short paper promoting the concept of “saline agriculture.” Discusses salt-tolerant crops (particularly halophytes), the limited success of genetic engineering, the use of saline water for irrigation, the benefits of saline agriculture for renewable energy, raw materials for industrial use, and combining the growing of halophytes with aquaculture of sea fish and shrimps.

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