Development of Comprehensive Soil Salinity Index

Crop yield is a function of many agroclimatic factors. However, excessive wetness, dryness, or soluble salts in the root zone are three important stresses that inhibit crop growth and reduce yield. Stress due to wetness can be expressed by an index such as SEW30 (sum of excess water over 30 cm); however, a similar index is not available for stress due to soil salinity. An index, the sum of excess salinity over threshold (SEST), is proposed here. This index represents the cumulative salinity status of the root zone with respect to a specific crop in excess of the cropʹs threshold level. Specifically, it incorporates the sum of daily salinity excesses over the threshold salinity level of the crop at different points in the root zone and over a specific cropgrowth stage (or over an entire cropping period). The proposed salinity index, however, needs to be evaluated with field data before it can be used to characterize salt buildup in soil under different irrigation regimes.