The Relation between Irrigation Water Salinity and Soil Salinity

A clear understanding of the relation between irrigation water and soil salinity is necessary for precise analysis of data obtained from salinity experiments or from field observations. Soil salinity is expressed in terms of salinity of saturation extract (EC e) and soil solution) ECss with the use of EC e being more common. Often it is assumed that soil salinity (EC e) is always greater than irrigation water salinity (ECiw). However¡ EC e can be less or greater than ECiw. The determining factor in setting this relation is the amount of leaching fraction. In the layer within the root zone where leaching fraction is high¡ EC e is less than ECiw. Field data show that EC e within the root zone can even become less than half of ECiw. It is also shown here that EC e in the interval between two irrigation episodes does not change and remain constant¡ while ECss increases with time because of the crop water uptake.