Sustainability of irrigated agriculture in Iran is threatened by the salinization of land and water
resources. These problems are the result of seepage from unlined canals, inadequate provision
of surface and subsurface drainage, poor water management, and cultural practices and use of
saline water for irrigation. Approximately, half of the irrigated area falls under different types
of salt-affected soils and average yield losses may be as high as 50 percent. The annual economic
losses due to salinity are estimated to be more than US$ 1 billion. The problems of salinity
and water logging are not just agricultural problems, but they do affect the country as a whole
and ultimately the social fabric of Iranian society. Salt-prone land and water resources have
very adverse social and economic effects on communities, causing poor living standards in
affected areas and health problems for humans and animals. This situation has forced the local
population to abandon their lands and migrate to other areas to earn their living.
Despite these huge challenges, there is no national strategic plan available that directs research
on salinity and water logging assessment and management. In addition, no comprehensive database
is available to evaluate the extent and characterization of salt-prone land and water resources.
Furthermore, there are large differences in various studies conducted for the quantification of
salt-prone land and water resources, which raise serious concerns about the reliability of data.
The review of fragmented database reveals that the problems of salinity/ sodicity and water
logging are spread over a range of landscapes, including irrigated lands, rainfed dryland farming
areas and rangelands. Since most investigations have been carried out on selected soil profiles
or on soil samples collected from potentially salt-affected soils, it is not possible to categorize
these soils in terms of relative distribution of different types. As a general assessment, slightly
and moderately salt-affected soils are mostly found on the piedmonts at the foot of the Elburz
(Alborz) Mountains in the northern part of the country. The soils having severe to extreme salinity
are predominantly located in the Central Plateau, the Khuzestan and Southern Coastal Plains
and the Caspian Coastal Plain.
Natural leaching of salts from agricultural fields is not possible as rainfall is generally
insufficient. The process of salinization of the surface water resources is mainly due to natural
conditions, and to a lesser extent, to the discharge of drainage water into the river systems.
Estimates show that about 6.7 km3
of brackish water flow annually through 12 major rivers.
Some large-scale projects have been carried out on the management of saline water resources.
Over the last three decades, several approaches have been used to ameliorate salt-affected
soils in Iran to enhance their productivity. These include leaching practices to remove excess
salts from the root zone, use of chemical amendments, application of higher rates of fertilizers
to mitigate salinity effects, growing of salt-tolerant plant species, and improvement in genotypes
of commonly grown field crops. Although some improvements have been observed in isolated
places, little has been translated to a larger scale. Despite all these efforts, problems of soil
degradation still persist in vast tracts of irrigated areas because farmers generally lack knowledge
of important aspects of proper management of saline soils and irrigation waters of different quality.
The recent trends and future projections suggest that the need to produce more food and fiber
for the expanding Iranian population will lead to an increase in the use of salt-prone water and
land resources for crop production systems. Therefore, an assessment of the impact such use
will have on the environment and crop productivity will inevitably have to be made through a
holistic approach.
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There is no straightforward solution to the complex problems of salt-induced soil and water
resources degradation in Iran. The approaches addressing the management of these resources need
to be multidimensional and must take into account the biophysical and environmental conditions
of the target area as well as livelihood aspects of the associated communities. The following
priorities are likely to add value to the existing and future strategies of Iranian policy makers,
researchers, extension workers and farmers: (1) development of salinity preparedness programs
for salinity management, databases and maps of salinity hotspots, awareness programs for policy
makers and researchers, and potential markets for the agricultural produce from salt-prone areas;
(2) use of innovative applications of indigenous and advanced knowledge for salinity management;
(3) introduction of conservation initiatives for field crops such as wheat, barley, and cotton as
well as halophytic plant species capable of growing and producing on salt-affected lands; (4)
improved management of saline drainage water in areas where these waters predominate and their
disposal options are limited; (5) community-based management of salt-prone land and water
resources that would help in strengthening linkages among researchers, farm advisors, and farmers
as well as minimize the chances of developing secondary salinization.