Soil moisture sensors can be a valuable tool for farmers to manage their irrigation, however clay content of soil can interfere with their ability to accurately read soil moisture water. We calibrated two soil moisture sensors--the Acclima TDR315 and the Campbell Scientific CS655-- for five Nebraska soils whose clay content ranged from 5 to 49%.
We found the manufacturer’s calibration decreased in accuracy in soils that had higher clay content. To resolve this issue we developed a simple, user-friendly correction for clay content for these two sensors. This approach may also be applicable to similar sensors in soils with high clay content.
Publication: Singh, J., T.Lo, D.R.Rudnick, S.Irmak, and H.Blanco-Canqui (2019). Quantifying and correcting for clay content effects on soil water measurement by reflectometers. Agricultural Water Management 216 (390-399).