Abstract
Soil salinity/sodicity is the major problem in irrigated and rain-fed areas and are a continuous threat for the sustainability of agricultural production. The presence of salt affected soils has been identified as a major process of land degradation and the greatest cause of declining productivity by causing a detrimental effect on biological, physical and chemical properties of the soil system. Therefore, the objective of this topic is to review the impacts of salinity/sodicity on soil- water relations and plant growth in dry land areas in relation to their extent, distribution and development so as to manage and efficiently utilize the limited natural resources under irrigation and rain-fed farm lands. Land degradation by salinization is often found in Arid and Semi-Arid lands where irrigation of unsuitable soils or with poor quality water is a common practice. Moreover, dry land salinity is also mainly a function of rising groundwater tables, caused by increased recharges. Soils having soluble salts in solution and/or Na + ions or both on exchange sites exceeding certain limits that can adversely affect soil plant health by disturbing the biological , physical and chemical properties of the soil to the lower limit are classified as saline, sodic and saline sodic by taking into consideration of their pH, ECe and ESP. High levels of salinity have negative impact and potentially lethal effects on plants growth. On the other hand, high sodium concentration causes sodium-induced dispersion like reduced infiltration, reduced hydraulic conductivity and surface crusting while salts like calcium and magnesium, do not have this effect because they are smaller and tend to cluster clay particles and keep the soil to be flocculated since they compete for the same spaces as sodium to bind clay particles and reduce the amount of sodium-induced dispersion. High salt levels in the soil affects the nutrient balance in the plant or interfere with the uptake of some nutrients. Salt affected soils restricts plant growth and nutrient uptake due to osmotic forces. Keywords: Salt Afected Soils, Dry land, Soil-Water, Soil Properties DOI: 10.7176/JNSR/12-3-01 Publication date: February 28 th 2021
Highlights
The majority of the population in the arid and semi-arid areas depend on agriculture and pastoralism for subsistence
Dry land areas are those with less than three months of enough moisture to support plant growth, with an average temperature of at least 27°C and the rainfall is less than 40% of the potential evapotranspiration
Integrated catchment management in dry land areas are often neglected while expanding agricultural development
Summary
The majority of the population in the arid and semi-arid areas depend on agriculture and pastoralism for subsistence. Poor irrigation agriculture in arid and semi-arid regions results in land degradation through soil salinity and sodic soil developments in different parts of the world. Poor water transmission properties of sodic sub-soils, low rainfall in dry land areas, transpiration by vegetation and high evaporation during summer has caused accumulation of salts in the root zone soil layers. Salt affected soils could found in cold (permafrost), temperate, subtropical, and tropical belts, that is, all the way from the sub-arctic to the equator and for south of it which has a continental or arid climate and where, evapo-transpiration exceeds precipitation either permanently or at least some time of the year They are extremely wide spread throughout the various continents of the world and occupy extensive areas globally (Gupta and Abrol, 1990). This is the problem of Argentina, Egypt, India, Iraq, Pakistan, Syria and Iran (Rhoades and Corwin, 1990)
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