How many soil moisture sensor probes do I need to measure an area?
The probe part of the sensor is approximately 4 inches long (for the VG400) and .3 inches wide, and provides accurate readings for the medium with which it is in direct contact. If the soil is homogeneous and receives similar watering over an area then a single probe will give a representative reading for that area. If regions of soil are different in composition, for example sandy or loamy, then you may want to use a probe for each type of soil region, and for areas that receive different watering.
