Correcting Inaccurately Recorded Data due to Faulty Calibration of a Capacitance Water Content Probe

Abstract

Measuring soil water content by capacitance probes requires rigorous calibration to achieve acceptable accuracy. Some of the capacitance probes' users might take several readings using the default device calibrations or other prestored calibrations by mistake. This can lead to logging of faulty readings for periods of up to months or years. This study aimed to (1) study the importance of probe calibration and the level of error that results from using flawed calibrations and (2) to develop a mathematical method to correct the faulty recorded data. This research involved studying eleven scenarios of faulty calibrations including errors in the air/water calibration and in the in-soil calibration. A mathematical method was developed to correct the faulty recorded data and comparisons were made for the data after and before correction. Results indicated that using the manufacturer's default calibration within the software resulted in substantial error values especially for heavy textured soils. It is recommended that users and especially researchers should perform rigorous in-soil calibration wherever the probe is installed, and they should repeat the calibrations whenever the soil structure changed.