Shouldn’t POGO measure the moisture content across a deeper depth (to ensure it includes the entire root system?)

No! The predominant moisture and salinity exchange with the root system of all types of turf occurs in t the top 2” to 2.5” of the root system. This is why POGO was designed to measure the top 2.2” inches for moisture and salinity. When the sensor is measuring too deep, you are diluting the measurement outside of the most influential region.