This paper presents a possibility current-voltage curve interpretation, registered in the saturated soil, in categories of soil salinity evaluation. A quantity containing the information about the salinity is electric conductivity of the soil. This conductivity can be evaluated by the analysis of the slope of a straight line, fitted into the part of the current-voltage curve, which is responsible for the reduction of hydrogen ions during the electrolysis of the water contained in the soil. It gives a chance to evaluate simultaneously the oxygen flux density and the soil salinity in conditions of maximum humidity, i.e., in a situation, when the availability of oxygen is minimum and it can be a limitation of the plant growth and when the mobility of ions, dissolved in the soil solution is maximum.