紫色土坡耕地土壤大孔隙流的定量评价  

Quantitative evaluation of macropore flow in purple soil of sloping cropland

作　　者：王红兰[1,2] 蒋舜媛[2] 崔俊芳[1] 唐翔宇 

机构地区：[1]中国科学院成都山地灾害与环境研究所,成都610041 [2]四川省中医药科学院,成都610041

出　　处：《农业工程学报》2017年第22期167-174,共8页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家重点研发计划课题(2016YFD0800203);国家自然科学基金项目(41501237;41471268)

摘　　要：为阐明大孔隙丰富且孔径呈两极分化的紫色土坡耕地土壤大孔隙流的运移规律,通过室内土柱试验获取耕作层0~20 cm、非耕作层20~40 cm原状土柱和填装土柱的穿透曲线,分析饱和条件下土壤大孔隙流发生规律,并采用解析法CXTFIT软件拟合了水分优先运移参数,PFSP指标(大孔隙流引起的穿透曲线延展量与水动力弥散作用及两区作用引起的延展量的比值)定量评价土壤大孔隙流的贡献率。研究结果表明:1)以填装土柱水流为平衡基质流计算,耕作层0~20 cm原状土柱中大孔隙流的导水贡献率为66.2%~68.5%,而Br-累积淋出量占总淋出量的62.3%~66.1%。对于非耕作层20~40 cm,土壤大孔隙流导水贡献率为0.2%~1.7%,而Br-随大孔隙流运移的比例却达14.5%~20.5%。说明耕作层土壤中大孔隙流现象远比在非耕作层土壤中更为显著;2)PFSP值结果表明大孔隙流作用对穿透曲线延展量的贡献率最大,两区交换运移作用次之,水动力弥散作用的最小。即PFSP值越大,大孔隙流对总水流通量的贡献率越大。The importance of macropore flow as a preferential flow mechanism for infiltrating water and transport of solutes has been generally recognized during a couple of decades. Macropore flow plays significant roles in the structured soil, such as leading to more infiltration and thus reducing overland flow and rapidly transferring pesticides and other pollutants through the soil macropores into the groundwater. Due to its critical effect on field-scale soil water flow and transport of contaminants in soils, macropore flow is gaining more interest. In this study, soil samples were collected at depths of 0-20 cm and 20-40 cm from sloping cropland of purple soil, which are located at Yanting Agro-ecological Experimental Station of Purple Soil （105？27？E, 31？16？N）, hilly central Sichuan, Southwest China. Using Br- tracer and simulated rainfall methods, lab-scaled disturbed and undisturbed soil column experiments were conducted to characterize the preferential transport behavior and evaluate the contribution of preferential flow based on simulations with the CXTFIT model. The breakthrough curves （BTCs） for each soil column were also obtained by analyzing the dynamics of Br- in the outflow. The integrated parameter, PFSP, defined as the ratio of extended quantity of BTCs due to preferential flow to extended quantity of BTCs caused by hydrodynamic dispersion and two-region effect, was calculated based on BTCs and CXTFIT datasets of the undisturbed soil columns. The BTCs of undistributed soil column showed an early breakthrough of Br- and also an upturned tail, indicating the presence of both preferential flow and matrix flow in studied soil. The preferential flow contributed 66.2%-68.5% of water discharge and 62.3%-66.1% of cumulative Br- discharge from undisturbed soil columns collected at the 0-20 cm depth, and at the 20-40 cm depth, their contributions was 0.2%-1.7% and 14.5%-20.5%, respectively. These implied that preferential flow made a much greater contribution to cumulative Br- disc

关 键 词：土壤 径流 坡地 大孔隙流 土柱试验 Br-示踪 

分 类 号：S157.1[农业科学—土壤学]