On the improved Brutsaert's model to estimate the soil water content by measuring P-wave and S-wave speeds: A commentary on Xu et al. (2020)

The importance of measuring the soil water content cannot be overestimated. One of the emerging methods is to estimate the water content by measuring the elastic wave speeds through the soils. While Xu et al. (2020) discuss this important measurement technology, there appear to be several mistakes made in their paper, and hence their findings may be unreliable.