This study determined the importance of high frequency sensors in clay soils. Seven sensors were tested to evaluate their calculations of permittivity, which is then used to determine soil moisture, especially in clay, saline soils. There are two classes of sensors; high frequency and low frequency. The study determined that low frequency sensors cannot accurately determine permittivity in clay or saline soils. Acclima sensors are classed with high frequency, research grade sensor costing thousands of dollars. High frequency sensors are essential to accuracy. Most commercial moisture sensors are low frequency sensors that cannot maintain their accuracy when the chemical conditions of the soil change, especially in clay soils. To maintain accuracy the sensors must use high frequency. The study concluded that Acclima sensors are as accurate as the highest frequency, very expense, research sensors. The bottom line is Acclima moisture sensors are like having an advanced laboratory sensor in your turf.
Standardizing Characterization of Electromagnetic Water Content Sensors
Summary by Acclima.