High residual sodium carbonate water in the Indian subcontinent: concerns, challenges and remediation

Water scarcity has become one of the major limiting factors in global agriculture, particularly in the arid and semi-arid regions of the world. This necessitates irrigation with marginal-quality waters including those with high levels of residual sodium carbonate (RSC) and an important water quality parameter. Extended use of high RSC water leads to accumulate sodium in the soil which alters physical and chemical properties of soils. The electrical conductivity is a good index of salinity while sodium adsorption ratio (SAR) that of sodicity hazard of irrigation water. It has been found that waters with high RSC values are more hazardous compared to no RSC water of equal SAR. Sustainable agriculture on these soils demands to adopt certain site-specific management strategies prior to use such low-quality waters for the economic production of crops. Strategies like dilution with low salt water and addition of calcium-based amendments, along with organic manures have been traditionally practiced and giving some promising results. It is well documented that for improving plant growth, irrigation to achieve low leaching fraction is necessary for the purpose of reducing the transport of solutes that are responsible for the degradation of water quality and provides an efficient use of limited water supplies. In addition, implementations of government policies and public–private sector collaborations are necessary to find new horizons for the management of high RSC irrigation waters in arid and semi-arid regions of the world. This article provides an overview of soil permeability problems associated with the irrigation using high RSC waters.