生物炭对黄绵土水分吸渗特征及水力学参数的影响

Effects of biochar on water absorption characteristics and hydraulic parameters of loessial soil

探究不同生物炭添加量对宁南山区黄绵土水分吸渗特征及水力学参数的变化,为提升区域生态功能及促进农业生产提供数据支撑。选取6种生物炭添加量(0、10、20、30、40和50g/kg),通过室内一维水平土柱试验,利用Philip模型拟合土壤吸渗过程并确定吸渗率(S),并推导出Van Genuchten模型中进气吸力倒数(a)、形状系数(n)及水吸力(h),利用上述水力学参数拟合土壤水分特征曲线、非饱和导水率及比水容量。结果表明:随着生物炭添加量增大,各处理湿润锋运移距离及累积入渗量均逐渐减小。与未添加生物炭处理相比各处理S分别降低了7.83%、14.99%、16.90%、23.36%和39.50%;随生物炭添加量增加,a、n及饱和导水率(K_(s))逐渐减小,饱和含水率(θ_(s))、滞留含水率(θ_(r))逐渐增大。相同土壤含水率下,生物炭添加量增加h增大,非饱和导水率减小且增长速率逐渐降低。相同h下,生物炭添加量越大比水容量越大,水分有效性越高。可以看出添加生物炭显著增强了宁南山区黄绵土持水性能及水分有效性。

The effects of different amount of biochar additions on the water absorption characteristics and hydraulic parameters of loessial soil in the mountainous area of southern Ningxia were explored to provide data support for improving regional ecological functions and promoting agricultural production.Six level of biochar addition(0,10,20,30,40 and 50g/kg)were selected and a one-dimensional horizontal absorption experiment was conducted.The Philip model was used to fit the soil absorption process and determine the absorption rate(S).The reciprocal of intake suction(a),the shape coefficient(n)and water suction(h)in the Van Genuchten model were derived.The above hydraulic parameters were used to fit the soil water characteristic curve,unsaturated hydraulic conductivity and specific water capacity.The results showed that the wetting front migration distance and cumulative infiltration amount of each treatment decreased gradually with the increase of biochar addition amount.Compared with no biochar treatment,S decreased by 7.83%,14.99%,16.90%,23.36%and 39.50%,respectively.With the increase of biochar addition amount,a,n and saturated hydraulic conductivity decreased gradually,saturated water content and retention water content increased gradually.Under the same soil moisture content,with the increase of biochar addition,the amount of h increased,the unsaturated hydraulic conductivity decreased,and the growth rate gradually decreased.Under the same h,the greater the amount of biochar added,the greater the specific water capacity,the higher the water effectiveness.Biochar addition significantly enhanced the water holding capacity and water availability of loessial soil in the Ningxia.