Soil Moisture Measurement by using Seismic Waves

The work proposes an accurate, on-site and real-time method to measure the moisture content of agricultural soils; the idea is to estimate the moisture measuring the velocity of propagation of seismic waves in the medium applying a new model based on the use of both compressional and shear waves. In a previous paper the authors derived the relationship between the compressional wave speed and the moisture content for various kind of soils; they also derived the conditions for the actual validity of the proposed relationships and a suitable range of frequencies for the sound used as the input stimulus, for a wide range of agricultural soils in different physical conditions. In this paper, the use of shear wave velocity is proposed aiming to increase the accuracy of moisture estimation and to reduce the number of parameters affecting the measurement without increasing the computational charge. Finally, using the results obtained, they propose a portable, accurate and very cheap sensor suitable for direct use by farmers and/or not specialized personnel.