Calibration of a soil moisture sensor with disturbed and undisturbed soil samples from Bahia

Abstract

The objective of this study was to evaluate the models proposed by manufacturers and in the literature with respect to soil moisture measurement and to evaluate the performance of the CS616 sensor in the calibration of disturbed and undisturbed soil samples. These calibrations were performed using linear and quadratic models. Disturbed samples were collected in São Gabriel/BA, six samples placed in pots, whereas undisturbed samples were collected in Cruz das Almas/BA, three samples directly collected in the area and placed in a container. A calibration was performed between 21/12/2016 and 08/01/2017. The models proposed in the literature and by manufacturers differed in the estimation of volumetric soil moisture. Disturbed soil samples had higher data dispersion than undisturbed samples, due to factors such as grain size and bulk density, which influence the calibration data. The CS616 sensor had satisfactory performance in the calibration of disturbed and undisturbed samples, with excellent fit of the soil moisture data. Using soil moisture contents obtained by the CS616 sensor, without a previous calibration, may lead to errors in the results, confirming the need for a specific calibration for each type of soil.

The Effect of Fertilization on Time Domain Reflectometry Probe Measurement Accuracy in the Field Experiment in Slovakia

“…where: V w -volume of soil water phase (cm 3 ); V t -total volume of the soil sample (cm 3 ) (Antal and Igaz, 2012;Shukla et al, 2014;Lima et al, 2018) Simultaneously, TDR equipment was used for the purposes of performing the measurements at the same time and location of soil sampling. The TDR measurements were performed using HydroSense II system -model CS659 (Campbell Scientific, Inc.®).…”

“…Accurate measurement of soil moisture is essential for many investigations in agriculture, horticulture, ecology, forestry, hydrology, civil engineering, waste management and other environmental fields (Smith and Mullins, 2001;Chandler et al, 2014;Susha et al, 2014;Shaikh et al, 2019;Abbaspour-Gilandeh et al, 2018). Methods used for determination of the soil moisture content are divided into direct gravimetric methods, relying on the principle of determining the amount of water in the soil, and the indirect methods, relying on the principle of measuring the specific soil property which is dependent on soil moisture (Quinones and Nemeth, 2003;Antal and Igaz, 2012). Gravimetric method can be performed on both disturbed and undisturbed soil samples and it is not affected by the soil type and salinity and is easily computable.…”

“…TDR is nowadays well-established method that determines the soil moisture content using the frequency in the range from 10 MH z to 12 GH z . Application of TDR principles for determination of soil moisture has been widely accepted as an alternative method proposing an empirical relationship between the dielectric constant of soil and soil water content (Smith and Mullins, 2001;Quinones and Nemeth, 2003). Considering the saline soils, in certain cases, the imaginary part of the dielectric constant can also affect the TDR reading.…”