Profiling probes measure soil moisture (and often other attributes like temperature) across a vertical soil profile, typically spanning a range of 30cm to 120cm. Soil profiling probes typically consist of multiple single-point sensors housed within an elongated enclosure, although some, like the GroPoint Profile feature modular segments which form a single antenna for continuous measurement across the entire length. A soil profiling probe is installed in the soil vertically.
Measuring soil moisture at multiple depths is important for optimizing irrigation, as it helps characterize the penetration of water throughout the root zone.
The chief advantage of using a soil profiling probe is the elimination of the cost of multiple single-point sensors and the need to excavate a large hole in order to bury them at the appropriate depths.
Profiling probes are usually manufactured as parallel pairs of rings along a probe or rod, and are typically installed in plastic or PVC access tubes where the electric field between the sensor and the soil must pass through the plastic tube. This design imposes uncertainties as to whether the access tube, soil, or meniscus that can form on the outside of the access tube following rainfall or irrigation, is being measured. The volume of measurement and its geometry are also uncertain (Topp 2003). Profiling probes which don’t require an access tube will typically provide greater accuracy for this reason. The GroPoint Profile (which also uses the superior TDT method of moisture measurement) and Hydrascout HSTi are examples.