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Updated: May 13, 2026
08:31
The Calibration and Use of Capacitance Sensors to Monitor Stem Water Content in Trees
Published on: December 27, 2017
Can root electrical capacitance be used to predict root mass in soil?
R C Dietrich1, A G Bengough, H G Jones
1The James Hutton Institute, Invergowrie, Dundee, UK.
Annals of Botany
|March 16, 2013
Summary
Plant capacitance measurements are not a direct assay for root mass. A new model shows capacitance is influenced by substrate water content and stem tissue, not solely root biomass.
Area of Science:
- Plant physiology
- Electrical engineering
- Soil science
Background:
- Electrical capacitance is commonly used to estimate plant root mass.
- Conventional models interpret capacitance using parallel cylindrical capacitors.
- Recent research suggests this interpretation is flawed, proposing a new model.
Purpose of the Study:
- To test a new plant capacitance model in solid substrates.
- To investigate the relationship between plant capacitance, substrate properties, and plant tissue.
Main Methods:
- Determined capacitance of compost and soil based on water content.
- Measured capacitance of cereal plants in various substrates and irrigation conditions.
- Analyzed capacitance using an electrical circuit model with series components.
Main Results:
- Substrate capacitance increased with water content, exceeding plant tissue capacitance.
- Maximum plant capacitance in solid substrates correlated with stem cross-sectional area.
- Capacitance measurements were modeled as series capacitors (plant tissue and substrate).
Conclusions:
- The new physical interpretation of plant capacitance was supported.
- Substrate and plant capacitance combine according to physical laws.
- Measured capacitance is primarily determined by stem base tissue in wet substrates, not a direct root mass assay.
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