生物质炭短期添加对不同类型土壤水力性质的影响

Effects of Short-termed Biochar Application on Hydraulic Properties of Different Types of Soils

为探究生物质炭添加对农田土壤水力性质的影响,以我国10个地区农田耕层土壤为供试土样,通过室内模拟试验,研究4种生物质炭添加比例下(C0、C5、C10和C15,生物质炭体积占比分别为0%、5%、10%和15%)土壤饱和导水率(Ks)、水分特征曲线及van Genuchten模型拟合参数和水分常数的变化特征。结果表明:生物质炭添加对土壤渗透性能的影响与土壤质地密切相关;添加生物质炭后,砂粒含量较高的风砂土和黄绵土的Ks显著降低,C15的降幅分别为89.2%和85.0%;而黏粒含量较高土壤的Ks普遍升高,C15处理下赤红壤的增幅高达158.9%。生物质炭添加改变了土壤的持水能力,且变幅随着生物质炭添加量的增加而增大。生物质炭添加提升了各类土壤的饱和含水量(0.7%~17.6%)和低吸力段的持水能力;生物质炭添加对中、高吸力水平下各类土壤持水能力的影响存在差异,大致表现为砂质土持水能力提升、残余含水量增大、α值降低;而壤质、黏质土持水能力下降,残余含水量、田间持水量及凋萎系数均降低。研究结果可为考虑生物质炭施用的平衡模拟提供水力学基础参数,并为各地区农田生物质炭的合理施用提供科学依据。

A laboratory simulation experiment was conducted to investigate the influence of biochar application on hydraulic properties of arable topsoils from ten regions in China.Biochar was incorporated into the soils at the volume rate of 0%(C0),5%(C5),10%(C10)and 15%(C15),respectively.The results indicated that the effect of biochar on soil permeability were determined by soil texture,the saturated hydraulic conductivity declined in aeolian sandy soil and yellow loamy soil with high sand content due to the application of biochar,which were decreased by 89.2%and 85.0%respectively when the application rate of biochar was 15%(C15).However,the addition of biochar commonly increased the permeability of soils with high clay content,especially for lateritic red soil,whose saturated hydraulic conductivity increased by 158.9%.Furthermore,the soil water-holding capacity varied with the application of biochar,and C15 showed the most obvious difference.Applying biochar improved the saturated soil water content by 0.7%–17.6%and water-holding capacity under low soil water suction.There were differences among the effects of biochar addition on water-holding capacities of various soils at medium and high suction levels.The application of biochar increased the water-holding capacity and residual water content but decreasedαvalues of sandy soils,while decreased the water-holding capacity,residual water content and wilting coefficient of loam and clay soils.The results can provide basic hydraulics parameters for water balance simulation considering biochar application,and provide a scientific basis for the reasonable application of biochar into cropland soil.