On the Use of a Water Potential Probe for Suction and Temperature Measurements in Unsaturated Natural Clayey Soil

The accurate measurement of soil suction is essential for understanding the behavior of unsaturated soils, particularly in soil–vegetation–atmosphere (SVA) interactions, where both energy and hydraulic gradients due to climatic action exhibit their maximum intensity. This study assesses the performa...

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Main Authors: Nico Stasi, Vito Tagarelli, Osvaldo Bottiglieri, Francesco Cafaro
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Applied Sciences
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Online Access:https://www.mdpi.com/2076-3417/15/6/3021
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author Nico Stasi
Vito Tagarelli
Osvaldo Bottiglieri
Francesco Cafaro
author_facet Nico Stasi
Vito Tagarelli
Osvaldo Bottiglieri
Francesco Cafaro
author_sort Nico Stasi
collection DOAJ
description The accurate measurement of soil suction is essential for understanding the behavior of unsaturated soils, particularly in soil–vegetation–atmosphere (SVA) interactions, where both energy and hydraulic gradients due to climatic action exhibit their maximum intensity. This study assesses the performance of the TEROS 21 probe, a capacitance-based water potential sensor, for measuring soil matric suction and temperature in clayey soils of the South Apennines, Italy. Laboratory tests were conducted on soil samples with varying moisture contents, and the results were compared with those obtained using the traditional filter paper (FP) method and high-capacity tensiometers (HCTs). The TEROS 21 (METER Group, Inc., Pullman, WA, USA) sensor demonstrated a reliable performance, especially at suction levels between 300 and 2000 kPa, though there was some dependency on the initial sensor conditions (wet or dry). The temperature data obtained from the TEROS 21 were verified by using a thermocouple, showing the high consistency of the readings. This study showed that the filter paper and sensor measurements aligned at a water content lower than 30% but diverged at higher levels due to method-specific accuracy limitations. The consistent sensor results confirmed the measurement’s reliability. The air-entry value (AEV) of the soil water retention data was identified at around 800 kPa, which is consistent with previous findings.
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spelling doaj-art-dc8c303760dd4eeb8d2c06ae00967f2b2025-08-20T02:42:41ZengMDPI AGApplied Sciences2076-34172025-03-01156302110.3390/app15063021On the Use of a Water Potential Probe for Suction and Temperature Measurements in Unsaturated Natural Clayey SoilNico Stasi0Vito Tagarelli1Osvaldo Bottiglieri2Francesco Cafaro3Department of Civil, Environmental, Land, Building Engineering and Chemistry, Polytechnic University of Bari, 70126 Bari, ItalyDepartment of Civil, Environmental, Land, Building Engineering and Chemistry, Polytechnic University of Bari, 70126 Bari, ItalyDepartment of Civil, Environmental, Land, Building Engineering and Chemistry, Polytechnic University of Bari, 70126 Bari, ItalyDepartment of Civil, Environmental, Land, Building Engineering and Chemistry, Polytechnic University of Bari, 70126 Bari, ItalyThe accurate measurement of soil suction is essential for understanding the behavior of unsaturated soils, particularly in soil–vegetation–atmosphere (SVA) interactions, where both energy and hydraulic gradients due to climatic action exhibit their maximum intensity. This study assesses the performance of the TEROS 21 probe, a capacitance-based water potential sensor, for measuring soil matric suction and temperature in clayey soils of the South Apennines, Italy. Laboratory tests were conducted on soil samples with varying moisture contents, and the results were compared with those obtained using the traditional filter paper (FP) method and high-capacity tensiometers (HCTs). The TEROS 21 (METER Group, Inc., Pullman, WA, USA) sensor demonstrated a reliable performance, especially at suction levels between 300 and 2000 kPa, though there was some dependency on the initial sensor conditions (wet or dry). The temperature data obtained from the TEROS 21 were verified by using a thermocouple, showing the high consistency of the readings. This study showed that the filter paper and sensor measurements aligned at a water content lower than 30% but diverged at higher levels due to method-specific accuracy limitations. The consistent sensor results confirmed the measurement’s reliability. The air-entry value (AEV) of the soil water retention data was identified at around 800 kPa, which is consistent with previous findings.https://www.mdpi.com/2076-3417/15/6/3021soil matric suctionTEROS 21unsaturated soilsfilter paper methodhigh-capacity tensiometerssoil water content
spellingShingle Nico Stasi
Vito Tagarelli
Osvaldo Bottiglieri
Francesco Cafaro
On the Use of a Water Potential Probe for Suction and Temperature Measurements in Unsaturated Natural Clayey Soil
Applied Sciences
soil matric suction
TEROS 21
unsaturated soils
filter paper method
high-capacity tensiometers
soil water content
title On the Use of a Water Potential Probe for Suction and Temperature Measurements in Unsaturated Natural Clayey Soil
title_full On the Use of a Water Potential Probe for Suction and Temperature Measurements in Unsaturated Natural Clayey Soil
title_fullStr On the Use of a Water Potential Probe for Suction and Temperature Measurements in Unsaturated Natural Clayey Soil
title_full_unstemmed On the Use of a Water Potential Probe for Suction and Temperature Measurements in Unsaturated Natural Clayey Soil
title_short On the Use of a Water Potential Probe for Suction and Temperature Measurements in Unsaturated Natural Clayey Soil
title_sort on the use of a water potential probe for suction and temperature measurements in unsaturated natural clayey soil
topic soil matric suction
TEROS 21
unsaturated soils
filter paper method
high-capacity tensiometers
soil water content
url https://www.mdpi.com/2076-3417/15/6/3021
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