The Effect of Humic Acid on Soil Physicochemical and Biological Properties under Salinity Stress Conditions in Pot Culture of Satureja khuzistanica Jamzad

Aims High salt accumulation has severe adverse effects on soil characteristics. Humic acid can improve the soil structure, soil microbial communities, and absorption and maintenance of mineral nutrients. The aim of the present study was to determine the effects of humic acid on some physicochemical and biological soil properties in soils under salt stress. Materials Methods The experiment was conducted as a factorial based on RCBD design with four replications. The first factor included humic acid in five levels (zero, 10, 20, 30, and 40mg kg^-1 soil). The second factor was salinity stress in five levels (0, 25, 50, 75, and 100mM NaCl). The sampling was carried out in two stages, before and after harvest. Findings The results showed that S1H5 treatment had the lowest soil electrical conductivity (EC), soil reaction (pH), bulk density, and population of actinomycetes with average values of 0.26dS m^-1, 6.21, 1.12g cm^-3, and 516cell g^-1 of soil and had the highest fungal and bacterial population with an average of 1525000 and 137500000cell g^-1 of soil, respectively. Conclusion Salt stress has a significant effect on physicochemical and biological soil properties except for the population of actinomyces that their activity was better, at a high level of salinity stress, it had adverse effects on other properties. Although using humic acid improved soil properties. According to the results, using humic acid can be a good solution to reduce the adverse effects of salt stress.