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| DOI：10.13522/j.cnki.ggps.2019236 |
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| Method to adjust the soil water retention curve measured using centrifuge apparatus |
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REN Jian, ZHANG Wuping, WANG Guofang, HUANG Mingjing, QIAO Lei
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1.Shanxi Agricultural University, College of Resources and Environment, Taigu 030800, China;2.Shanxi Agricultural University, Software Institute, Taigu 030800, China;3. Arid Farming Research Center, Shanxi Academy of Agricultural Sciences, Taiyuan 030000, China
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| Abstract: |
| 【Objective】Centrifuge is a common apparatus to measure soil water retention curve, but the resultant soil compression is an issue that might compromise its accuracy and reliability. The purpose of this paper it to present a method to correct such inferiorities.【Method】We measured the water retentions of 16 repacked soils with contrasting texture and organic matter (OM) taken from Shanxi province using a centrifuge apparatus. In the experiment, we measured the initial soil volume, dynamic soil volume, as well as water content under different spinning speeds. A multiple nonlinear regression model was derived to describe the dependence of the matric potential on volumetric moisture content, soil particle sizes, volumetric soil mass and OM; it was then verified against the experimental data. 【Result】The logarithm of the matric potential was linearly related to mass fractions of the sand, clay, OM and volume of the water. The accuracy of the model was 74%, with an average relative error of 14.460% for the modelled samples, and of 13.237% for the samples used for verification. It was also found that soil texture affected predictivity of the model. The matric potential was negatively correlated to the mass fraction of sand, volumetric soil mass and water content, but positively correlated to the mass fraction of clay and organic matter.【Conclusion】The nonlinear regression model linking the matric potential to soil water content, with the change in soil volume modified, was able to improve the accuracy of the centrifuge method; it has implications in soil hydraulic parameter measurement. |
| Key words: soil water retention; multiple nonlinear regression model; centrifuge method; virtual numerical simulation |
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