膨润土添加对沙土持水能力的改善

Improvement of the Water Holding Capacity of Sandy Soil by the Addition of Bentonite

沙土质地粗、保水能力较差,不利于植被存活,改善颗粒级配能提高土壤的持水能力,促进植被重建。为改善沙土的持水能力寻找合适的比例,研究进行0~50μm膨润土和150~200μm沙粒的混合实验,测量混合土壤容重、土壤含水量、总孔隙度、毛管孔隙度、非毛管孔隙度和土壤累积蒸发量,分析膨润土含量对沙土持水能力的影响。结果表明:膨润土的添加显著降低了土壤容重和非毛管孔隙度,增加了土壤的总孔隙度和毛管孔隙度,提高了土壤的持水能力。与对照组相比,膨润土的添加使土壤饱和持水量增加,累积蒸发量减小,蒸发时间显著延长,土壤的保持水分能力得到增强,更有利于植物吸收利用。随着膨润土比例的增加,土壤饱和持水量表现出逐渐增加的趋势,累积蒸发量表现出逐渐减小的趋势。该研究结果可为我国西北干旱区沙土的生态修复提供技术支持。

Sandy soil is not conducive to the survival of vegetation as the poor water-holding capacity and coarse texture of sandy soil.The water-holding capacity of sandy soil would be improved if its grain size distribution could be adjusted reasonably,being suitable for the vegetation reconstruction.In order to find appropriate improving materials and mixing ratio to improve the water-holding capacity of sandy soil,the experiment is conducted to mix 0~50μm bentonite and 150~200μm sand particles.The bulk density,soil water content,total porosity,capillary porosity,non-capillary porosity and cumulative evaporation of the mixed soil are measured,and the effect of the addition of Bentonite on the water-holding capacity of sandy soil is analyzed.The results show that the addition of Bentonite significantly reduces the soil bulk density and non-capillary porosity,and increased the total porosity and capillary porosity of the soil,and improves the water holding capacity of the soil.With the increase in the proportion of Bentonite,the bulk density and non-capillary porosity of soil decrease gradually,and the total porosity and capillary porosity increase gradually.Compared with the control group,the addition of Bentonite increases the soil saturated water capacity and residual water,decreases the cumulative evaporation,significantly prolongs the evaporation time,and enhances the water retention capacity of the soil,which is more conducive to plants.With the increase in the proportion of Bentonite,the soil saturated water holding capacity and residual water shows a trend of increasing gradually,while the cumulative evaporation shows a trend of decreasing gradually.The addition of Bentonite can also make the loose aeolian sand grains on the soil surface stick together,make the soil surface become dense and hard,and restrain the evaporation of soil moisture to a certain extent,this slows the release of water from the soil,allowing the soil to retain more water over a longer period of time.The results can provide technical support for the ecological restoration of sandy soil in the arid area of northwest China.