| Cite this article: | 高晓飞.低吸力段土壤持水特性测定方法的比较[J].灌溉排水学报,,():-. |
| Gao Xiaofei.低吸力段土壤持水特性测定方法的比较[J].灌溉排水学报,,():-. |
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| Comparison of Measuring Methods for Soil Water Holding Characteristics in Low Suction Stage |
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Gao Xiaofei
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Faculty of Geographical Science, Beijing Normal University
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| Abstract: |
| 【Background】Soil water holding properties are important soil physical parameters. 【Objective】The soil moisture changes significantly with the change of soil water suction in the low suction stage. The measurement method determines the comparability of the data and the measurement time consuming. 【Method】Three common instruments were used to measure the soil water holding characteristics in the low suction stage, including: sand box, pressure plate apparatus and HYPROP system. The water-holding properties of black soils with different degrees of erosion were measured. 【Result】The results show that the measurement results of the sand box method are higher than that of the pressure plate apparatus at pF1.5 and below; the measurement results of the sand box method and the pressure plate instrument are similar at pF1.8 and above. The data measured by the HYPROP evaporation method are always lower than the results of the combined sand box-pressure plate apparatus. Below pF1.0, the differences are extremely significant. At pF0.0, the average difference in soil moisture content measured between the two methods is 3.55%; at pF1.0, the difference between the two is 1.20% on average. Above pF1.0, the average is 0.5%-1.26%. As the suction value increases, the difference between the two tends to decrease. However, the situation is different for soils with different degrees of erosion. For severely eroded soils with large bulk and light texture, the results of the two methods are less different; for soils with small bulk density and heavy texture, there is a big difference between the two.【Conclusion】Therefore, when using the HYPROP method to determine the water characteristic curve of the low suction stage of the soil with low bulk density and heavy texture, it may be necessary to use the sand box method to measure the data below pF1.0 instead of the data measured by the evaporation method. However, the HYPROP method has a shorter test cycle and a wider range of suction than the sand box method, which is very suitable for rapid determination of a small amount of samples. |
| Key words: Soil water retention characteristics; sand box method; pressure plate method; HYPROP evaporation method |
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