A direct-current four-electrode method for the measurement of electrical conductivity of soils in situ was devised. Red copper electrodes and a high voltage (90 V) were used. Measurements were made several minutes after the insertion of electrodes into the soil, and readings were taken 10-20 seconds after the passing of current through the circuit. It was found that electrical conductivity values measured by the proposed method were nearly equal to those measured by alternating-current four-electrode method, with a mean proportional factor of 1.006 for 31 measurements, and had a close relationship with those. measured also in situ by conventional two-electrode method. It is shown by the application of this method that, in addition to salinity aml the distribution of soluble salts in the profile for salinized soils, electrical conductivity may be used as a comprehensive. indez of soil fertility of the cultivated layer of acid and even neutral soils as well as base status of the profile, and also reflects the effect of fertilization the on content, of soluble ions of soils.