Ultrasonic dispersion equipment has been developed to investigate soil aggregate stability. An ultrasonic probe was vibrating in water containing soil aggregates. Constant vibration amplitudes of 0.5, 1 and 2 μm were used in ultrasonic soil aggregate stability measurements. Ultrasonic power determined with an energy balance method was 0.7, 2.7 and 8.9 W for the three amplitudes. Vibration amplitudes were close to the cavitation limit of gas saturated deionized water, which was found at 0.5-0.6 μm measuring absorbance with diode array spectrophotometer. Cambisol and Chernozem from a long-term tillage experiment in Lower Austria were investigated. The treatments were conventional, reduced and no tillage. Dissolved organic carbon measured with ultrasonic extraction was higher in Cambisol than in Chernozem. Measuring soil aggregate stability according to DIN norm showed greater stability of Cambisol than of Chernozem, however, can hardly show influences of tillage. Ultrasonic soil aggregate stability showed greater stability of Cambisol. Additionally, the ultrasonic soil aggregate stability method can demonstrate significant influences of soil tillage on aggregate stability ie stability decreased from no tillage to reduce tillage and conventional tillage for both soils. Ultrasonic soil aggregate stability measurements correlated with total organic carbon content in aggregates. Total organic carbon content was greater in no tillage than in conventional tillage and larger in Cambisol than in highly degraded Chernozem.