Effect of Salt-Water Irrigation on Soil Characteristics and Plant Biomass at Different Exposure Durations

Abstract

Soil salinity is a major abiotic stress that threatens agricultural productivity by altering soil physicochemical properties, disrupting nutrient availability, and imposing osmotic and ionic stress on plants. The present study investigated the effects of salt irrigation on soil properties and shoot and leaf biomass in Vigna radiata L. (mung bean) cultivar GUJ4 under greenhouse conditions. Plants were exposed to 40 mM salt irrigation for 15 and 35 days, and changes in soil physicochemical properties, nutrient dynamics, and leaf and shoot biomass were evaluated. Salt treatment induced marked alterations in shoot and leaf biomass and the soil characteristics, particularly with respect to electrical conductivity (EC), pH, nitrogen fractions, phosphorus availability, and mineral nutrient balance. Correlation analysis revealed strong interrelationships among soil salinity, nutrient availability, mineral balance, and plant biomass. Na⁺ and EC were positively correlated with pH and ammonia but negatively associated with potassium, nitrate, available phosphorus, copper, iron, and calcium, with particularly strong negative correlations with potassium (r = −0.89 and −0.94, respectively). These alterations likely contributed to an unfavorable rhizosphere environment, ultimately restricting plant growth and biomass production. Thus, these findings suggest that salinity's detrimental effect on mung bean growth was not due to increased salt concentration alone but to broader disruptions in soil ionic balance and nutrient dynamics.