عنوان مقاله [English]
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 (ECe) and soil solution) ECss with the use of ECe being more common. Often it is assumed that soil salinity (ECe) is always greater than irrigation water salinity (ECiw). However, ECe 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, ECe is less than ECiw. Field data show that ECe within the root zone can even become less than half of ECiw. It is also shown here that ECe in the interval between two irrigation episodes does not change and remain constant, while ECss increases with time because of the crop water uptake.