Soil Moisture Measurements: Comparison of Instrumentation Performances
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Volume 136, Issue 2
Abstract
It has long been recognized that reliable, robust, and automated instrumentation for the measurement of soil moisture content can be extremely useful, if not essential, in hydrological, environmental, and agricultural applications. A number of automated techniques for point measurement of soil water content have been developed to operational level over the past few decades. While each of those techniques has been individually calibrated by the gravimetric method, typically under laboratory conditions, there have been few studies that made a direct comparison between the various techniques, particularly under field conditions. This paper compares probes, EC-5 (both sensors based on capacitance measurements, developed by Decagon Devices) and time domain reflectometer sensors (CS616 Campbell Scientific Water Content Reflectometer), with gravimetric data and with each other, under field conditions. Data were collected during two field experiments characterized by different soils and a wide range of soil moistures, resulting from irrigation/drying cycle. Results show that all the tested probes give acceptable results after being calibrated in the field. The capacitive sensors can be used in each type of soil with the same calibration equation, independently from depth, with root mean square error (RMSE) ranging between 2.5 and 3.6%. Time Domain Reflectometry probes showed a dependence on depth but a lower RMSE (1.6%).
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Acknowledgments
This research was funded by the Italian Ministry of University and Research (MiUR), in the frame of the Project No. UNSPECIFIED2004070118_003, “Survey of energy and mass fluxes over vines and bare soil between rows in an Italian vineyard.” The writers warmly thank the “Tenuta Col d’Orcia” winery for hosting this research.
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Published In
Journal of Irrigation and Drainage Engineering
Volume 136 • Issue 2 • February 2010
Pages: 81 - 89
Copyright
© 2010 ASCE.
History
Received: May 27, 2008
Accepted: Jun 30, 2009
Published online: Jan 15, 2010
Published in print: Feb 2010
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