Soil salinity problems are primarily associated with coastal areas and irrigated
lands in the dry zones. Salinity is a major environmental factor that drastically
affects the crop productivity throughout the world. Yadav (2003) reported that salt
affected soils are distributed in 120 countries covering 953 M ha and reduced
productivity to 7-8% at the global scale. Soil salinity has arrested the productivity
of agriculture land and in many cases rendered land uncultivable. Considering the
impact of saline soil on crop production, a regional program involving
Bangladesh, India, Pakistan and Sri Lanka was initiated with the objectives to (i)
document existing reclamation systems of saline soil in SAARC region, (ii)
compare and identify saline soil problems and appropriate reclamation techniques,
and (iii) disseminate reclamation methods to the researchers, extension agencies,
and policy makers in the SAARC region. Based on the country report and a
regional expert consultation meeting the study attempts to provide a regional
perspective on the salinity problem and suggests way forward to share best
practices among the SAARC Member countries to enhance agricultural
production and food security.
Salinity occurs through natural or human-induced processes that result in the
accumulation of dissolved salts in the soil water to an extent that inhibits plant
growth. A saline soil is defined as having a high concentration of soluble salts and
electrical conductivity of ECE of 4 dS/m or more. There are mainly two types of
salinity a) Inherent or salinity due to par cut materials underneath the soil profile;
and b) Coastal salinity due to intrusion of saline water in land. There are number
of factors responsible for the Stalinization of an area, depending on its situation.
The land relief and degree of flooding mainly affect the formation of coastal
saline soils. The other factors are: i) the nature of the soil, ii) precipitation, iii)
tidal action, iv) the effect of the river system and their discharges, v) depth of the
ground water table and salt deposits, and vi) the slope of the ground and the
proximity to drainage channels. Sodicity is a secondary result of salinity in clay
soils, where leaching through either natural or human-induced processes has
washed soluble salts into the subsoil, and left sodium bound to the negative
charges of the clay.