High-power ultrasonic instruments have been used extensively for dispersing soil particles and aggregates. This paper proposes a method for calculating the dispersive energy, a component of the ultrasonic energy used to disrupt the bonds maintaining soil aggregates. The design and development of a technology to record the power used to disrupt the soil aggregates by simultaneously monitoring the change in temperature of the aggregated soil–water system and the total input power to the ultrasonic instrument is described. A theory is formulated to calculate the efficiency of the ultrasonic energy applied to the aggregated soil. Using this measurement system, the calculation of dispersive energy for a vertisol and a ferrosol was demonstrated.