Review
Crop and irrigation management strategies for saline-sodic soils and waters aimed at environmentally sustainable agriculture

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Abstract

Irrigation has long played a key role in feeding the expanding world population and is expected to play a still greater role in the future. As supplies of good-quality irrigation water are expected to decrease in several regions due to increased municipal–industrial–agricultural competition, available freshwater supplies need to be used more efficiently. In addition, reliance on the use and reuse of saline and/or sodic drainage waters, generated by irrigated agriculture, seems inevitable for irrigation. The same applies to salt-affected soils, which occupy more than 20% of the irrigated lands, and warrant attention for efficient, inexpensive and environmentally acceptable management. Technologically and from a management perspective, a couple of strategies have shown the potential to improve crop production under irrigated agriculture while minimizing the adverse environmental impacts. The first strategy, vegetative bioremediation—a plant-assisted reclamation approach—relies on growing appropriate plant species that can tolerate ambient soil salinity and sodicity levels during reclamation of salt-affected soils. A variety of plant species of agricultural significance have been found to be effective in sustainable reclamation of calcareous and moderately sodic and saline-sodic soils. The second strategy fosters dedicating soils to crop production systems where saline and/or sodic waters predominate and their disposal options are limited. Production systems based on salt-tolerant plant species using drainage waters may be sustainable with the potential of transforming such waters from an environmental burden into an economic asset. Such a strategy would encourage the disposal of drainage waters within the irrigated regions where they are generated rather than exporting these waters to other regions via discharge into main irrigation canals, local streams, or rivers. Being economically and environmentally sustainable, these strategies could be the key to future agricultural and economic growth and social wealth in regions where salt-affected soils exist and/or where saline-sodic drainage waters are generated.

Introduction

Irrigation has ever been an important factor in agricultural development. The area of land under irrigation in the world has expanded substantially, particularly in the second half of the last century. Between the mid-1960s and the mid-1980s, expansion of irrigation has accounted for more than 50% increase in global food production (El-Ashry and Duda, 1999). Although only approximately 17% of the world's cropland is irrigated, it produces more than a third of the food and fiber harvested throughout the world (Hillel, 2000). The expansion in irrigated agriculture needs to continue as the world population increases, but annual renewable freshwater resources for the foreseeable future are now largely allocated. There may be some areas where freshwater resources increase or decrease according to rainfall changes due to climate change, however, these are likely to occur at the level that is small compared to the increased future demands for freshwater (Wallace, 2000). Competition for freshwater already exists among the municipal, industrial and agricultural sectors in several regions due to an increase in population. The consequence has been a decreased allocation of freshwater to agriculture (Tilman et al., 2002). This phenomenon is expected to continue and to intensify in less developed, arid region countries that already have high population growth rates and suffer from serious environmental problems.

As supplies of good-quality irrigation water are expected to decrease, available water supplies need to be used more efficiently (Oweis et al., 1999, Hatfield et al., 2001, Wichelns, 2002), where one of the techniques can be the reuse of saline and/or sodic drainage waters generated by irrigated agriculture (Shalhevet, 1994, Rhoades, 1999, Oster, 2000), or of marginal-quality waters generated by municipalities (Bond, 1998, Bouwer, 2002). The same applies to salt-affected soils, which occupy more than 20% of the irrigated lands (Ghassemi et al., 1995), and warrant attention for efficient, inexpensive and environmentally acceptable reclamation and management to improve crop production (Qadir and Oster, 2002). If mismanaged, the use of such poorer quality waters and soils can increase salinity and sodicity problems, which already plague many irrigation projects reducing crop yields.

A major problem with irrigated agriculture is its negative environmental impacts. Irrigated agriculture, over the long-term, cannot avoid causing adverse off-site effects due to the drainage water it generates (Van Schilfgaarde, 1994). The generation of drainage water by irrigation is a necessity to maintain soil salinity, through leaching, at acceptable levels for crop growth. However, it is no longer sufficient to set leaching requirement objectives based solely on irrigation water salinity and crop salt tolerance. Nor is it sufficient to limit the objectives of soil reclamation, or rehabilitation, to reducing soil salinity and sodicity to levels that permit high levels of crop productivity. The environmental impacts of the drainage waters generated by reclamation, rehabilitation and irrigation in general must also be considered. What is the disposal site for the drainage water, or more to the point, the salt it contains? What will be the impact on the chemical composition of the receiving waters or soil strata? The key issues are: (1) What can be done to minimize the volume of drainage water? (2) Should the disposal of unusable drainage water be localized to the sub-regions where these waters are generated. One strategy to deal with such issues is to improve irrigation management (Wichelns, 2002) so that excess water is not applied over that needed for evapotranspiration and leaching. Another is to reuse drainage waters for irrigation of appropriate salt-tolerant crops (Rhoades, 1999).

In the future, sustainable irrigation systems using saline-sodic soils and waters have the potential to improve crop production with minimized adverse environmental effects. This will require a comprehensive approach to soil, water and crop management. The foci will need to be on reclamation of new lands, rehabilitation of saline and sodic lands generated by past irrigation practices, improved productivity per unit of water, and environmental protection. Crop and water management will play key roles in such a comprehensive approach, and are the foci of this review.

Section snippets

Vegetative bioremediation of sodic and saline-sodic soils

Accumulation of salts and sodium (Na+) in salt-affected soils originates either through the weathering of parent minerals (causing fossil or primary salinity/sodicity) or from anthropogenic activities involving the inappropriate management of land and water resources (contributing to man-made or secondary salinity/sodicity). Excess salinity levels do not have adverse impacts on soil structure and its physical and hydraulic properties. Rather, saline conditions may have favorable effects on soil

Reusing drainage waters for irrigation

Drainage from irrigated lands is a necessity for irrigation to be sustainable. Drainage waters carry a salt load that is always higher, sometimes substantially higher, than that of the irrigation water. In many instances, drainage water does not flow directly back to the rivers from which the irrigation water was obtained. Saline geologic deposits and saline groundwaters often exist along the flow path. As drainage water flows through these deposits, or displaces the saline groundwater, the

Crops for vegetative bioremediation and drainage water reuse strategies

An appropriate selection of plant species capable of producing adequate biomass is vital during vegetative bioremediation and different drainage water reuse strategies. Such selection is generally based on the ability of a crop to withstand elevated levels of soil salinity and sodicity while also providing a saleable product or one that can be used on-farm. Salinity may reduce crop yields by disturbing the water and nutritional balance of plants (Maas and Grattan, 1999). Sodicity affects plant

Future perspective

Despite limitations with the freshwater supplies, particularly in water-starved countries, there will be an increasing need for more water to meet the needs of municipal, industrial and agricultural sectors. With increasing population, less and less freshwater will be available for agricultural use. Consequently, the use and reuse of saline and/or sodic irrigation waters is expected to increase in the future. This scenario generates a need to modify existing soil and crop management practices

References (102)

  • M Qadir et al.

    Reclamation of a saline-sodic soil by gypsum and Leptochloa fusca

    Geoderma

    (1996)
  • M Qadir et al.

    Use of saline-sodic waters through phytoremediation of calcareous saline-sodic soils

    Agric Water Manage

    (2001)
  • J.D Rhoades

    Intercepting, isolating and reusing drainage waters for irrigation to conserve water and protect water quality

    Agric Water Manage

    (1989)
  • J Shalhevet

    Using water of marginal quality for crop production: major issues

    Agric Water Manage

    (1994)
  • D.P Sharma et al.

    Strategy for long term use of saline drainage water for irrigation in semi-arid regions

    Soil Till Res

    (1998)
  • P.G Van der Moezel et al.

    Screening for salinity and waterlogging tolerance in five Casuarina species

    Landscape Urban Plan

    (1989)
  • J.S Wallace

    Increasing agricultural water use efficiency to meet future food production

    Agric Ecosyst Environ

    (2000)
  • N Ahmad et al.

    Amelioration of a calcareous saline-sodic soil by gypsum and forage plants

    Land Degrad Rehabil

    (1990)
  • Z Aslam et al.

    Salt tolerance of Echinochloa crusgalli

    Biol Plant

    (1987)
  • J.E Ayars

    Field crop production in areas with saline soils and shallow saline groundwater in the San Joaquin Valley of California

  • L Batra et al.

    Microbiological and chemical amelioration of alkaline soil by growing Karnal grass and gypsum application

    Exp Agric

    (1997)
  • P.P Bhojvaid et al.

    Reclaiming sodic soils for wheat production by Prosopis juliflora (Swartz) DC afforestation in India

    Agroforestry Systems

    (1996)
  • W.J Bond

    Effluent irrigation—an environmental challenge for soil science

    Aust J Soil Res

    (1998)
  • H Bouwer

    Integrated water management for the 21st century: problems and solutions

    J Irrig Drain Eng

    (2002)
  • V Cervinka

    Agroforestry farming system for the management of selenium and salt on irrigated farmland

  • M.R Chaudhry et al.

    Economics and effectiveness of biological and chemical methods in soil reclamation

    Pak J Agric Res

    (1988)
  • H.P Cresswell et al.

    Subsoil amelioration by plant roots—the process and the evidence

    Aust J Soil Res

    (1995)
  • A Dinar et al.

    Optimal ratios of saline and non-saline waters for crop production

    Soil Sci Soc Am J

    (1986)
  • M.C Drew

    Plant injury and adaptation to oxygen deficiency in the root environment: a review

    Plant Soil

    (1983)
  • M.T El-Ashry et al.

    Future perspectives on agricultural drainage

  • Elkins CB, Haaland RL, Hoveland CS. Grass root as a tool for penetrating soil hardpans and increasing crop yields. In:...
  • P Farrington et al.

    Controlling dryland salinity by planting trees in the best hydrogeological setting

    Land Degrad Dev

    (1996)
  • L.E Francois et al.

    Salt tolerance of safflower

    Agron J

    (1964)
  • L.E Francois et al.

    Effect of salinity on grain yield, and quality, vegetative growth, and germination of triticale

    Agron J

    (1988)
  • M.A Garduno

    Kochia: a new alternative for forage under high salinity conditions of Mexico

  • V.K Garg

    Interaction of tree crops with a sodic soil environment: potential for rehabilitation of degraded environments

    Land Degrad Dev

    (1998)
  • A Ghafoor et al.

    Using brackish water on normal and salt-affected soils in Pakistan: a review

    Pak J Agric Sci

    (1991)
  • F Ghassemi et al.
  • E.P Glenn et al.

    Salt tolerance and crop potential of halophytes

    Crit Rev Plant Sci

    (1999)
  • Grattan SR, Rhoades JD. Irrigation with saline ground water and drainage water. In: Tanji KK, editor. Agricultural...
  • C.M Grieve et al.

    Purslane (Portulaca oleracea L.): a halophytic crop for drainage water reuse systems

    Plant Soil

    (1997)
  • J.L Hatfield et al.

    Managing soils to achieve greater water use efficiency: a review

    Agron J

    (2001)
  • D Hillel
  • M Ilyas et al.

    Hydraulic conductivity of saline-sodic soil after gypsum application and cropping

    Soil Sci. Soc. Am. J.

    (1993)
  • M.A Kausar et al.

    Comparison of biological and chemical methods for reclaiming saline-sodic soils

    Pak J Sci Res

    (1972)
  • B Kaur et al.

    Bioamelioration of a sodic soil by silvopastoral systems in northwestern India

    Agroforest Syst

    (2002)
  • W.P Kelley

    The reclamation of alkali soils

    Calif Agric Exp Sta Bull

    (1937)
  • W.P Kelley et al.

    Principles governing the reclamation of alkali soils

    Hilgardia

    (1934)
  • R Keren et al.

    Effect of saline water on soil properties and crop yield

    Hassadeh

    (1990)
  • K.C Knapp

    Economics of salinity and drainage management in irrigated agriculture

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