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| Titel |
Time-lapse electromagnetic induction surveys under olive tree canopies reveal soil moisture dynamics and controls |
| VerfasserIn |
Gonzalo Martinez, Juan Vicente Giraldez Cervera, Karl Vanderlinden |
| 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 |
250113218
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| Publikation (Nr.) |
 EGU/EGU2015-14969.pdf |
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| Zusammenfassung |
| Soil moisture (θ) is a critical variable that exerts an important control on plant status and
development. Soil sampling, neutron attenuation and electromagnetic methods such as TDR
or FDR have been used widely to measure θ and provide point data at a possible range of
temporal resolutions. However, these methods require either destructive sampling or
permanently installed devices with often limiting measurement depths, or are extremely
time-consuming. Moreover, the small support of such measurements compromises its value
in heterogeneous soils. To overcome such limitations electromagnetic induction
(EMI) can be tested to monitor θ at different spatial and temporal scales. This work
investigates the potential of EMI to characterize the spatio-temporal variability
of soil moisture from apparent electrical conductivity (ECa) under the canopy of
individual olive trees. During one year we measured θ with a frequency of 5 min
and ECa on an approximately weekly basis along transects from the tree trunk
towards the inter-row area. CS-616 soil moisture sensors where horizontally installed
in the walls of a trench at depths of 0.1, 0.2, 0.4, 0.6 and 0.8 m at five locations
along the transect, with a separation of 0.8 m. The Dualem-21S sensor was used to
measure weekly the ECa at 0.2 m increments, from the tree trunk to a distance of 4.4
m. The results showed similar drying and wetting patterns for θ and ECa. Both
variables showed a decreasing pattern from the tree trunk towards the drip line,
followed by a sharp increment and constant values towards the center of the inter-row
space. This pattern reflects clearly the influence of root-zone water uptake under the
tree canopy and higher θ values in the inter-row area where root-water uptake is
smaller. Time-lapse ECa data responded to evaporation and infiltration fluxes with the
highest sensitivity for the 1 and 1.5 m ECa signals, as compared to the 0.5 and 3.0 m
signals. Overall these preliminary results revealed the potential of EMI to monitor
the spatio-temporal variability of soil moisture fluxes under olive tree canopies. |
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