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| Calibration of TDR for soil moisture content at farmland of black soil region in northeastern China |
（1.School of Geography, Belling Normal university, 100875, Beijing, China；
2.State Key Laboratory of Earth Surface Processes and Resource Ecology, 100875, Beijing, China） |
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Abstract It is necessary to calibrate time domain reflectometry (TDR) device when measuring the soil moisture content. In this study, a series of soil column tests were used to calibrate the TDR for soil moisture content. Four soil media (black soil and its parent, transition and sand horizon in turn) in black soil profile were selected as experiment objectives. The moisture content of the soil columns varied from wet to dry. The results showed that the TDR device underestimated soil moisture content in the study area. The soil moisture content measured by TDR method was significantly lower than that measured by the oven-dry gravimetric method. The model efficiency predicted by the exponential way was greater than that by the linear way. The function of soil moisture between TDR and gravimetric methods under the uniform medium can give a good estimation for the same medium (maximum absolute error 3.2%). The function of soil moisture content obtained from mixed media can be used for different soil media, with a maximum absolute error of 6.6%. The results can serve for determining soil moisture content at similar environments in the black soil region of northeastern China.
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Received: 05 March 2013
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