宁夏引黄灌区盐渍化土壤在改良剂作用下的水力特性试验

Experiments on Hydraulic Characteristics of Salinized Soils Improved by Conditioners in Yellow River Diversion Irrigation Area of Ningxia,China

为了研究宁夏引黄灌区盐渍化土壤在施加有机改良剂和无机改良剂后的水力特性,选取宁夏引黄灌区典型区域进行土壤改良并进行种植试验。将改良后的土壤分5层取样在实验室中进行土柱入渗试验,利用压力膜仪和自循环达西渗流试验仪,测量了土壤含水率与压力水头之间的关系和渗透系数;根据实测数据,选取van Genuchten(VG)模型进行参数反演,对不同改良剂处理后各层土壤水分特征曲线进行了对比分析。研究发现:(1)各层土壤在水吸力相同时,施加不同改良剂后的土壤含水率一般大于对照组,而有机改良剂处理组要大于无机改良剂处理组;(2)改良后水分特征曲线及相应VG模型中的参数发生了较大变化;(3)有机改良剂处理后土壤容重有所减小,而无机改良剂处理后土壤容重变化不太明显;(4)不同改良剂处理后土柱中水分入渗的湿润锋推进速度和土壤渗透系数有不同程度增大,有机改良剂处理组增大幅度大于无机改良剂处理组。综上所述,不同改良剂对土壤容重、含水率、水分入渗速度及其他水力参数都有较大影响,说明改良剂在一定程度上改变了土壤结构。土柱试验及种植试验均表明,有机改良剂(牛粪和糠醛渣)处理组的性态要优于无机改良剂(脱硫石膏和粉煤灰)处理组。

To study the hydraulic properties of salinized soil improved by organic and inorganic soil conditioners in the Ningxia Diversion Irrigation Area,a salinized farmland was chosen for soil improvement and planting experiments.Soils improved by various conditioners were sampled from five layers for column infiltration tests in a laboratory.Soil water content and pressure head were measured with a pressure-membrane meter,and the infiltration coefficient was measured with a self-circulating Darcy infiltration tester.Based on the measured data,van Genuchten(VG)model was employed for inversion calculation of soil hydraulic characteristics,and soil water characteristic curves of each layer were comparatively analyzed after different conditioner treatments.The results showed that:①Soil water contents after improvement were generally greater than that of the control group,and especially,soil water contents improved by the organic conditioners were greater than those by inorganic conditioners at the same soil suction.②Soil water characteristic curves and the parameters in VG model changed greatly after improvement compared with the control group.③Soil bulk density improved with organic conditioners decreased obviously,but it changed unclearly improved by inorganic conditioners.④Compared with the control group,the movement of wetting front and soil water infiltration coefficient increased to different degrees after improvement,which were better when improved with organic conditioners than by inorganic conditioner-s.In conclusion,soil conditioners can affect soil bulk density,water content,rate of soil water infiltration and other hydraulic parameters,indicating that they can change soil structure to a certain degree,organic amendments(cow dung and furfural slag)have better effects for soil properties than inorganic amendments(desulphurization gypsum and fly ash).