The disturbance of topsoil using ultrasonic waves

Abstract

One of the most important variables involved with agricultural fields operations is the condition of the soil. The design of soil working machines must be directed toward optimal manipulation of soil conditions in order to attain optimum soil conditions with minimum energy input. To accomplish this, a new idea to control soil compaction and use lower powered tractors for soil tillage is presented. It is based on using ultrasonic waves to disturb the soil profile to a depth of 15–25 cm. Ultrasonic waves are vibrational waves which oscillate orderly through a medium. When ultrasonic frequency reaches the natural frequency of soil, a resonance will occur and soil particles will vibrate. The maximum amplitude of the oscillating particles will cause disturbance in the soil profile resulting in a more loosened condition ultrasonic frequencies range from 20 kHz to 2 GHz, and the natural frequency of most soil types lie in this range. The device presented here consists of a rigid wheel with the two sides made of stainless steel plates and the peripheral thickness made of aluminum sheet. The wheel is filled with gel which is capable of transmitting the waves. A probe is used as the antenna generating these waves. The wheel disturbs a strip of soil whose width is equal to the width of the wheel. The tillage machine was tested in the field on a Jordanian clay loam soil and changes in soil physical properties were measured. The bulk density, total porosity and cone index data from this field experiment showed that significant loosening effects were present down to a depth of 20 cm. This seems to be the first demonstration of using ultrasonic waves technique to loosen the topsoil for agricultural purposes in the field.