Ultrasonic Aggregate Breakdown of an Oxisol as Affected by Cavitation Intensity

ABSTRACT

In the soil aggregate stability analysis using ultrasound, the absorbed energy by soil–water suspension is expressed in J mL⁻¹ or J g⁻¹. However, the same energy (J) can be obtained from different combinations of sonication time and power. We evaluated the effect of four different amplitudes (12, 18, 24, and 30 µm) by varying the sonication time in order to obtain the same total ultrasonic energy applied. Aggregates 4–8 mm size from a Brazilian Acrudox were sonicated using a sonicator probe-type. After each sonication, the soil aggregates were wet-sieved and obtained the oven-dried mass of aggregates (8–2 mm; 2–1 mm; 1–0.5 mm; 0.5–0.25 mm; and <0.25 mm). Different responses on soil aggregate breakdown were observed by varying the amplitude, although the amount of applied energy was the same. This work reinforces the need of description of all experimental conditions for suitable comparison of different results.

KEYWORDS:

• Soil aggregate stability
• soil dispersion
• ultrasonic method