The accuracy of three soil water potential sensors were investigated for undisturbed and disturbed clay loam
soil, in order to provide reference for soil water potential measurement and in-situ soil water characteristic curve
measurement. MPS-1, MPS-6 and pF water potential sensors and TDR315L soil moisture sensor were installed in the
undisturbed and disturbed clay loam soil respectively. The soil water characteristic curves were fitted by the laboratory
data and the sensor data, and then the accuracies of the three water potential sensors were compared. The results
showed that MPS-1 sensor had a narrow measurement range, but performed accurately in its range of measurement
when it was used in the disturbed and undisturbed clay loam soils. The MPS-6 and pF sensors had a wide
measurement range but a low accuracy. The MPS-6 sensors were temperature sensitive and pF sensors were unstable
during the measurement. The soil water characteristic curve fitted by MPS-1 sensors in the undisturbed and disturbed
clay loam soils had a higher coincidence with the control curve. The curves fitted by MPS-6 and pF sensors for
disturbed and undisturbed soils had good coincidences with the control curve at water content higher than 0.30 cm3
cm-3. Comparing the three water potential sensors, MPS-1 sensors are suitable to measure soil water potential in
undisturbed clay loam soil with water content higher than 0.30 cm3 cm-3 and in disturbed clay loam soil with water
content higher than 0.17 cm3 cm-3, MPS-6 sensors are suitable to measure soil water potential in undisturbed clay
loam soil and in disturbed clay loam soil with water content higher than 0.30 cm3 cm-3.
Key words: Soil water potential; Water potential sensor; Soil water characteristic curve
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