脱硫石膏对盐碱土一维水平吸渗特征及水分运动参数的影响

为探明添加脱硫石膏对盐碱土水分运动参数的影响,以改善和提高银川北部地区土壤结构和土地生产力,进行了室内一维水平土柱吸渗试验。选取6种脱硫石膏添加比例0,1.5%,3%,4.5%,6%和7.5%,探究不同脱硫石膏添加比例下盐碱土水平吸渗特征及水分运动参数的变化。结果表明:脱硫石膏添加减缓了土壤水分入渗过程,随着脱硫石膏添加比例增加,各处理累积入渗量与湿润锋运移距离均逐渐减小。幂函数与Philip模型能较好地拟合不同脱硫石膏添加比例下盐碱土水分吸渗特征,吸渗率随脱硫石膏配比增加逐渐减小,毛管力对水的吸持作用减弱。随着脱硫石膏配比增加,土壤饱和含水率依次增加,饱和导水率依次减小,土壤持水能力明显提高。在Brooks—Corey模型中,形状系数n逐渐增加,进气吸力h_d逐渐减小,土壤通气性增强。在相同含水率情况下,随着脱硫石膏配比增加,土壤水分扩散率减小。添加脱硫石膏增加了土壤持水性能,改变了土壤水分分布状况,对土壤水分运动参数有显著影响。研究结果可为合理利用脱硫石膏改良盐碱地提供参考依据。

Effects of Desulfurized Gypsum on One-dimensional Horizontal Imbibition Characteristics and Water Movement Parameters of Saline-alkali Soil

In order to explore the effect of adding desulfurized gypsum on the water movement parameters of saline-alkali soil, and improve and increase the soil productivity in the Yinbei Plain area, through an indoor one-dimensional soil column absorption test, 6 desulfurized gypsum treatments were selected:0, 1.5%, 3%, 4.5%, 6% and 7.5%, to study the horizontal infiltration characteristics and water movement parameters of saline-alkali soil. The results showed that the addition of desulfurized gypsum slowed down the process of soil moisture infiltration. As the proportion of desulfurized gypsum increased, the cumulative infiltration amount and the movement distance of the wet front of each treatment gradually decreased. Power function and Philip model could better fit the water movement characteristics of saline-alkali soil under different desulfurized gypsum addition ratios, and the absorption rate decreased with the increase of the desulfurization gypsum ratios, and the capillary force''s water holding effect weakened. As the proportion of desulfurized gypsum increased, the saturated water content of the soil increased and the saturated hydraulic conductivity decreased, the soil water holding capacity was significantly improved. The shape coefficient h_d in the Brooks-Corey model gradually decreased, and the intake suction h_d gradually increased, and soil aeration was enhanced. Under the same moisture content, the soil unsaturated water diffusivity gradually decreased with the increase of the desulfurization gypsum ratios. The addition of desulfurized gypsum increased the soil water holding capacity, changed the soil moisture distribution, and had a significant impact on soil water movement parameters. This study could provide theoretical support for the rational use of desulfurized gypsum to improve saline-alkali land.