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| Titel |
An algorithm for temperature correcting substrate moisture measurements: aligning substrate moisture responses with environmental drivers in polytunnel-grown strawberry plants |
| VerfasserIn |
Martin Goodchild, Stuart Janes, Malcolm Jenkins, Chris Nicholl, Karl Kuhn |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250102442
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| Publikation (Nr.) |
 EGU/EGU2015-1758.pdf |
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| Zusammenfassung |
| The aim of this work is to assess the use of temperature corrected substrate moisture data to
improve the relationship between environmental drivers and the measurement of substrate
moisture content in high porosity soil-free growing environments such as coir. Substrate
moisture sensor data collected from strawberry plants grown in coir bags installed
in a table-top system under a polytunnel illustrates the impact of temperature on
capacitance-based moisture measurements. Substrate moisture measurements made in our
coir arrangement possess the negative temperature coefficient of the permittivity of water
where diurnal changes in moisture content oppose those of substrate temperature.
The diurnal substrate temperature variation was seen to range from 7Ë C to 25Ë C
resulting in a clearly observable temperature effect in substrate moisture content
measurements during the 23 day test period. In the laboratory we measured the ML3 soil
moisture sensor (ThetaProbe) response to temperature in Air, dry glass beads and
water saturated glass beads and used a three-phase alpha (α) mixing model, also
known as the Complex Refractive Index Model (CRIM), to derive the permittivity
temperature coefficients for glass and water. We derived the α value and estimated the
temperature coefficient for water - for sensors operating at 100MHz. Both results are
good agreement with published data. By applying the CRIM equation with the
temperature coefficients of glass and water the moisture temperature coefficient
of saturated glass beads has been reduced by more than an order of magnitude to
a moisture temperature coefficient of |
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