Technology
Calibrate and verify probes before using their data to guide irrigation.
A probe may show a steady moisture value even when nearby soil is dry or saturated after irrigation. Check whether its data reflect conditions in the active root zone.
Sensor calibration compares an instrument’s output with a reference and sets or adjusts their relationship. For a soil probe, this helps translate its response into a useful moisture measure.
Sand, silt, clay, organic matter and salinity affect water retention or sensor response. The same displayed moisture value can mean different things in different soils.
An air gap, smeared soil around the probe, or incorrect depth can distort readings. Check placement and soil contact before assuming the instrument needs calibration.
Check soil at the probe’s depth, review rainfall and irrigation timing, and observe its response after wetting. A suitable reference sample can provide a numerical comparison.
Consider adjustment if repeated checks show a consistent offset, readings exceed the specified range, or the signal responds implausibly to wetting and drying. Rule out faults first.
Calibration changes the relationship between output and reference; verification checks performance, while troubleshooting searches for faults. Cleaning and data review support reliability but do not calibrate.
Interpret readings from relevant depths alongside crop demand, soil conditions and recent water inputs. Probes at multiple depths can help distinguish shallow wetting from root-zone replenishment.
For a practical check, compare probe data with nearby soil at the installed depth and the record of recent water inputs. For numerical comparison, sample similar soil and depth.
Check readings at commissioning, after disturbance or maintenance, and when field observations conflict. Follow the manufacturer’s calibration interval and record probe location, depth and soil zone.
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