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MONITORING OF SOIL WATER CONTENT IN A CITRUS GROVE USING CAPACITANCE ECH2O PROBES
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.orgCitation: Paper number 042110, 2004 ASAE Annual Meeting . @2004
Authors: M.S. Borhan, L. R. Parsons
Keywords: ECH2O probe, C-probe, calibration, real time monitoring, sandy soil, normalization
Two capacitance probes, the ECH2O and C-probe, have recently becomes available for monitoring soil water content. The relatively low cost ECH2O probe was calibrated, evaluated, and its performance was compared to the more expensive C-probe for real time monitoring of soil water status. Two calibration models were developed for a fine sand soil (> 95% sand, <3% clay, <1% organic matter) of central Florida. In Model 1, a linear regression was developed between probe output in millivolts (mV) and measured soil core volumetric water content at 6 moisture levels (0.0133, 0.0267, 0.04, 0.0533, 0.08, and 0.10 cm3 cm-3). Model 2 fits Air-Water normalization of mV values and measured soil core volumetric water content at 6 moisture levels. Performance of the models was found to be satisfactory. With Model 2 validation, observed R2, average prediction accuracy, standard error of prediction, and root means square errors were 0.98, 88%, 0.0042 cm3 cm-3 and 0.0041 cm3 cm-3, respectively. Both ECH2O and C-probes responded well with respect to irrigation, rainfall, and water uptake by the plants. Thus, this relatively low cost ECH2O probe has shown potential for continuous monitoring of soil moisture status in a fine sand soil of central Florida.