Measurement of moisture and salinity of dune sand soil under irrigation with water of high NaCl concentration
2004
Sakaguchi, Y. (Tottori Univ. (Japan). Arid Land Research Center) | Yamamoto, T. | Inoue, M.
The objective of this work was to study the accuracy of the calibration equations of the amplitude domain reflectometry (ADR) sensor, that measures volumetric soil water content (theta) and of the four electrode sensor, that measures soil solute concentration(C). Sand dune soil samples with known levels of theta and C were prepared. Then theta and C were measured using ADR and the four electrode sensors. Empirical calibration equations for each sensor were calculated. For ADR it was calculated by two methods: (i) by a constant coefficient and (ii) by a variable coefficient. For the four electrode sensor it was calculated by substituting theta calculated by these methods. Water and salt balances in weighing lysimeter were measured by the ADR and the four electrode sensors, using the constant coefficient, the variable coefficient and the traditionally used coefficient. It was found that the variable and the constant coefficients of the calibration equation, for both sensors, fitted better than the coefficient calculated by traditional method. Salt and water levels as calculated by the variable calibration coefficient were especially in good agreement with the real water and salt levels.
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