| 引用本文: | 孙召军,李金山,贾艳辉,等.干湿交替次数对土壤干密度和饱和导水率的影响[J].灌溉排水学报,2022,41(6):89-96. |
| SUN Zhaojun,LI Jinshan,JIA Yanhui,et al.干湿交替次数对土壤干密度和饱和导水率的影响[J].灌溉排水学报,2022,41(6):89-96. |
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| 摘要: |
| 【目的】研究干湿交替对原状土和扰动土土壤干密度（DD）和饱和导水率（Ks）的影响特征。【方法】通过室内试验对不同干湿交替条件下原状土和扰动土的干密度和饱和导水率测定，分析了不同干湿交替过程对土壤干密度和饱和导水率的变化特征及规律的影响。【结果】原状土干密度在1.41~1.89 g/cm3之间波动，扰动土干密度在1.47~1.85 g/cm3之间波动；原状土在第1次干湿交替后的干密度较原始干密度有大幅上升，随着干湿交替次数的增加逐渐趋于小范围波动，总体变异系数为8%；扰动土总体处于上升趋势，总体变异系数为5%；原状土干密度变化幅度显著大于扰动土（P＜0.05）。原状土饱和导水率在0.88~3.22 cm/h之间波动，扰动土饱和导水率在0.21~3.54 cm/h之间波动；原状土在经历不同干湿交替次数后呈上升的趋势，总体变异系数为39%；扰动土在经历不同干湿交替次数后饱和导水率呈现先下降后上升的趋势，总体变异系数为94%；原状土饱和导水率变化幅度显著小于扰动土（P＜0.05）。【结论】本试验条件下，土壤经历干湿交替后形成了较多水道，土壤透水性增强；大田翻耕后，表层土壤处于扰动松散状态，干密度较小，饱和导水率较大，而第1次灌水以后，干密度变大，饱和导水率降低，且干密度和饱和导水率在后续的生产过程中趋于稳定状态。 |
| 关键词: 干湿交替；土壤干密度；饱和导水率；土壤水分特性 |
| DOI：10.13522/j.cnki.ggps.2021635 |
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| Effects of Wetting-drying Cycles on Bulk Density and Saturated Hydraulic Conductivity of Soils |
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SUN Zhaojun, LI Jinshan, JIA Yanhui, LI Hao
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1. Farmland Irrigation Research Institute of Chinese Academy of Agricultural Sciences, Henan Key Laboratory of Water-saving Agriculture, Xinxiang 453002, China; 2. Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China
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| Abstract: |
| 【Objective】Changes in density and hydraulic conductivity of soil not only modulate subsurface hydrological processes but also affect root growth and root uptake of water and nutrients from soil. Understanding the mechanisms underlying their changes is thus critical to mitigating flooding and improving bioavailability of soil water. In this paper we studied how wetting-drying cycles often seen in the field change bulk density and saturated hydraulic conductivity of the soil. 【Method】Intact (mimicking zero-tillage) and disturbed (mimicking tillage) soil samples were taken from a cropped field. They were then subject to wetting-drying at different frequencies. During and at the end of the wetting-drying cycle experiment, we measured bulk density and saturated hydraulic conductivity of each soil sample. 【Result】Bulk density of the intact and disturbed soil samples varied in the range of 1.41~1.89 g/cm3 and 1.47~1.85 g/cm3 respectively. The bulk density of intact soils after the first wetting-drying cycle increased significantly followed by slight fluctuations in other wetting-drying cycles, with an average coefficient of variation 8%. In contrast, bulk density of the disturbed soils increased with the increase in wetting-drying cycles, with an average coefficient of variation 5%. Overall, the wetting-drying cycles affected the bulk density of intact soils more significantly than the disturbed soils (P<0.05). The saturated hydraulic conductivity of the intact and disturbed soils varied in the range of 0.88~3.22 cm/h and 0.21~3.54 cm/h, respectively. The saturated hydraulic conductivity of the intact soils increased with the increase in wetting-drying cycles, with an average coefficient of variation 39%. In contrast, the hydraulic conductivity of the disturbed soil decreased first followed by a decline with the increase in wetting-drying cycles, with an average coefficient of variation 94%. Wetting-drying cycles affected the hydraulic conductivity of the disturbed soils more significantly than the intact soils (P<0.05). 【Conclusion】Wetting-drying cycles resulted in cracks thereby reducing the bulk density and increasing saturated hydraulic conductivity of the soils. The effects, however, depend on tillage. Overall, wetting-drying cycles affect the bulk density of zero-tillage soil and saturated hydraulic conductivity of tilled soil more significantly. |
| Key words: wetting-drying cycles; bulk density; saturated hydraulic conductivity; soil moisture characteristics |
