Author
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Feng, Gary |
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Sui, Ruixiu |
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Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/27/2019 Publication Date: 1/30/2020 Citation: Feng, G.G., Sui, R. 2020. Evaluation and calibration of soil moisture sensors in undisturbed soils of Mississippi. Transactions of the ASABE. 63(2):265-274. https://doi.org/10.13031/trans.13428. DOI: https://doi.org/10.13031/trans.13428 Interpretive Summary: There is increasing interest and demand for growers and researchers to use soil moisture sensors for water management and research in the state of Mississippi, United States. Previous studies demonstrated great challenges in selection and deployment of the sensors for accurate monitoring soil moisture due to high variability of soil types and properties in nature. In this study, we evaluated and calibrated soil water content sensors TDR315 (Acclima, ID), CS655 (Campbell Sci., UT) and GS1 (Meter, WA) in on-site fields and using undisturbed soils in laboratory. We selected six predominant soil types across Mississippi state, including four clayey soils (Sharkey clay loam, Brooksville silty clay, Tunica clay, and Dowling clay) and two loamy soils (Commerce sandy loam and Leeper sandy loam) for the tests. Results indicated in general these three types of sensors with factory built-in calibration over-estimated volumetric water contents (Qv) of the soils in both field and laboratory. The Qv readings of these sensors were more close to the Qv determined by gravimetric method in sandy loam than clayey soils. The three types of sensors basically met their factory criteria of Root Mean Square Error (RMSE) in loamy soils. These sensors varied in their performance. Root Mean Squared Error (RMSE) of TDR315 ranged from 0.03 to 0.17 while CS655 and GS1 had greater RMSE ranging from 0.03 to 0.29 cm3 cm-3. Specific calibration of TDR315 and CS655 sensors was conducted for each of the six soils using combination of on-site field data and laboratory undisturbed soil data. Field validation on a clay and sandy loam soil suggested that accuracy of soil water content measured by CS655 and TDR315 probes was acceptable (R2>0.6) with proper in situ and undisturbed soil-specific calibration. Technical Abstract: There is increasing interest and demand for growers and researchers to use soil moisture sensors for water management and research in the state of Mississippi, United States. Previous studies demonstrated great challenges in selection and deployment of the sensors for accurate monitoring soil moisture due to high variability of soil types and properties in nature. In this study, we evaluated and calibrated soil water content sensors TDR315 (Acclima, ID), CS655 (Campbell Sci., UT) and GS1 (Meter, WA) in on-site fields and using undisturbed soils in laboratory. We selected six predominant soil types across Mississippi state, including four clayey soils (Sharkey clay loam, Brooksville silty clay, Tunica clay, and Dowling clay) and two loamy soils (Commerce sandy loam and Leeper sandy loam) for the tests. Results indicated in general these three types of sensors with factory built-in calibration over-estimated volumetric water contents (Qv) of the soils in both field and laboratory. The Qv readings of these sensors were more close to the Qv determined by gravimetric method in sandy loam than clayey soils. The three types of sensors basically met their factory criteria of Root Mean Square Error (RMSE) in loamy soils. These sensors varied in their performance. Root Mean Squared Error (RMSE) of TDR315 ranged from 0.03 to 0.17 while CS655 and GS1 had greater RMSE ranging from 0.03 to 0.29 cm3 cm-3. Specific calibration of TDR315 and CS655 sensors was conducted for each of the six soils using combination of on-site field data and laboratory undisturbed soil data. Field validation on a clay and sandy loam soil suggested that accuracy of soil water content measured by CS655 and TDR315 probes was acceptable (R2>0.6) with proper in situ and undisturbed soil-specific calibration. |
