Continuous wave acoustic method for determination of moisture content in agricultural soil

This work deals with the problem of measuring moisture content in agricultural soil by means of an on-site, easy to use and real-time acoustic wave system. The method is based on the propagation of an acoustic continuous wave (CW) with frequencies below 900 Hz through the soil. Speed of these acoustic waves enables estimation of water content and degree of saturation in the agricultural soil. It is argued that the change in the speed of sound in relation to the moisture content of the soil can be used for a continuous monitoring and control of irrigation of crops, thus leading to minimum use of irrigation water for optimal crop growth and to other associated advantages. The agreement between the experimental results obtained from the laboratory prototype and those obtained theoretically from Brutsaert's model for elastic wave propagation in soil–air–water system is presented.