Ali Hashemi

One of the most important factors involved with soil-engaging agricultural field operations is soil adhesion. Reducing soil adhesion has significant effects on the operation and energy consumption of agricultural machines. In this study, a laboratory method has been carried out to study the effects of ultrasonic waves on soil adhesion. Normal adhesion tests were performed on two types of soil using three plates with different contact areas. The plates consisted of an iron ring as the main body covered by a stainless steel sheet on the top and an aluminum sheet at the bottom. The internal space of the plates was filled with a fluid that was capable of transmitting the waves produced by piezoelectric crystals attached under the top sheet. When ultrasonic waves reached the metal surface which was in contact with the soil, soil adhesion force was measured while the plate was separating from the soil. Experimental results revealed that ultrasonic waves have a significant effect on soil adhesion in different moisture contents. The results of the analysis of variance (ANOVA) indicated that all the test parameters had significant effects on reducing the soil adhesion to the metal plates. However, multiple effects of frequency and other parameters on the soil adhesion were not significant. An increase in ultrasonic frequency from 0 to 1800 kHz had a significant effect on soil adhesion to metal plates at a 5% level. Results showed that the most effective application time that causes more reduction in soil adhesion is 60 s.