不同改性玉米秸秆生物炭对黄土丘陵地区土壤水力特性的影响

Effects of Different Modified Corn Straw Biochar on Soil Hydraulic Properties in Hilly Loess Areas

为了探究改性玉米秸秆生物炭对干旱黄土水分入渗、蒸发和持水等水力特性的影响,以玉米秸秆为研究对象,在N2环境下经500℃热解2 h制得玉米秸秆生物炭.选择H3PO4、NaOH和NH4Cl 3种溶剂,分别在2种浓度(1 mol·L^(-1)和3 mol·L^(-1))下通过浸渍改性法获得不同改性玉米秸秆生物炭.系统表征了所有生物炭的元素组成、孔隙结构、官能团和表面形貌等理化特性.选取每种玉米秸秆生物炭,分别在3个不同添加量(1%、2%和3%)下开展土壤水力特性试验,通过恒定水头法、土壤蒸发试验和水分特征曲线等,分析不同玉米秸秆生物炭对土壤饱和导水率、水分累计蒸发量和体积含水量的影响.结果表明,添加改性玉米秸秆生物炭可显著降低土壤饱和导水率5.74%~46.69%,提高土壤体积含水量0.74%~37.33%,促进土壤水分蒸发,而相比改性前土壤水分累计蒸发量降低0.63%~8.46%.随着生物炭添加量的增加,土壤饱和导水率显著降低,累计蒸发量逐渐增大,体积含水量呈现先增后减的趋势.改性溶液浓度与土壤饱和导水率、水分累计蒸发量和体积含水量均无相关性.研究可为提升陕甘黄土干旱地区土壤持水保水性能提供理论依据和技术支撑.

In order to investigate the influence of modified corn straw biochar on the hydraulic properties of water infiltration,evaporation,and water holding,corn straw biochar was prepared by pyrolysis at 500℃for 2 hours in an N2 environment.Three solvents(H3PO4,NaOH,and NH4Cl)were selected,and different modified corn straw biochars were obtained by immersion modification at two concentrations(1 mol·L^(-1) and 3 mol·L^(-1)).The physical and chemical properties of all biochars,such as elemental composition,pore structure,functional groups,and surface morphology,were systematically characterized.Each type of corn straw biochar was selected to perform soil hydraulic properties tests under three different additions(1%,2%,and 3%).The influence of different corn straw biochar on the soil saturated hydraulic conductivity,water accumulation evaporation,and volume water content were analyzed by constant head method,soil evaporation test,and soil moisture characteristic curve.The results showed that the addition of modified corn straw biochar can significantly reduce the soil saturated hydraulic conductivity by 5.74%-46.69%,improve the soil volume water content by 0.74%-37.33%,and promote the soil water evaporation,while reduce the soil water accumulation evaporation by 0.63%-8.46%before the modification.With the increase in biochar addition,the saturated hydraulic conductivity of the soil decreased significantly,the cumulative evaporation gradually increased,and the volume water content showed a trend of first increasing and then decreasing.There was no correlation between the modified solution concentration and the soil saturated hydraulic conductivity,accumulated evaporation,and volume water content.This study can provide theoretical basis and technical support for improving the water retention performance of soil in the loess arid region of Shaanxi and Gansu.