title: Laboratory Performance of Five Selected Soil Moisture Sensors Applying Factory and Own Calibration Equations for Two Soil Media of Different Bulk Density and Salinity Levels.
abstract: Non-destructive soil water content determination is a fundamental component for many agricultural and environmental applications. The accuracy and costs of the sensors define the measurement scheme and the ability to fit the natural heterogeneous conditions. The aim of this study was to evaluate five commercially available and relatively cheap sensors usually grouped with impedance and FDR sensors. ThetaProbe ML2x (impedance) and ECH₂O EC-10, ECH₂O EC-20, ECH₂O EC-5, and ECH₂O TE (all FDR) were tested on silica sand and loess of defined characteristics under controlled laboratory conditions. The calibrations were carried out in nine consecutive soil water contents from dry to saturated conditions (pure water and saline water). The gravimetric method was used as a reference method for the statistical evaluation (ANOVA with significance level 0.05). Generally, the results showed that our own calibrations led to more accurate soil moisture estimates. Variance component analysis arranged the factors contributing to the total variation as follows: calibration (contributed 42%), sensor type (contributed 29%), material (contributed 18%), and dry bulk density (contributed 11%). All the tested sensors performed very well within the whole range of water content, especially the sensors ECH₂O EC-5 and ECH₂O TE, which also performed surprisingly well in saline conditions.
authors.affiliation: Department of Water Resources, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences, Kamýcká 129, 165 21 Praha 6-Suchdol, Czech Republic. matula@af.czu.cz.
authors.forename: Svatopluk
authors.initials: S
authors.lastname: Matula
authors.affiliation: Department of Water Resources, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences, Kamýcká 129, 165 21 Praha 6-Suchdol, Czech Republic. batkova@af.czu.cz.
authors.forename: Kamila
authors.initials: K
authors.lastname: Báťková
authors.affiliation: Department of Water Resources, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences, Kamýcká 129, 165 21 Praha 6-Suchdol, Czech Republic. Wos_Lemma@yahoo.com.|Department of Water Supply and Sanitary, School of Environment and Energy Resource Engineering, Addis Ababa Science and Technology University, P.O. Box 16417, Addis Ababa, Ethiopia. Wos_Lemma@yahoo.com.
authors.forename: Wossenu Lemma
authors.initials: WL
authors.lastname: Legese
keywords: Frequency Domain Reflectometry (FDR); bulk density; comparison; factory calibration; impedance; own calibration; performance; salinity; sand; soil; water content sensors