紫色土坡耕地土壤大孔隙流的定量评价

发布时间：2019-01-08 10:40

【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。
[Abstract]:In order to elucidate the migration law of macropore flow in purple sloping farmland with rich macropores and polarizing pore size, the penetrating curves of undisturbed soil column and filled soil column in uncultivated layer of 0 ~ 20 cm, uncultivated layer for 20 cm, were obtained by laboratory soil column test. The occurrence law of soil macroporous flow under saturated condition was analyzed, and the moisture preferential migration parameters were fitted by analytic method CXTFIT software. The PFSP index (the ratio of penetration curve extension caused by macropore flow to hydrodynamic dispersion and the extension caused by two-zone interaction) was used to quantitatively evaluate the contribution rate of soil macroporous flow. The results show that: 1) the contribution rate of macroporous flow in undisturbed soil column is 66.2% and 68.5%, which is calculated by using filled soil column flow as balance matrix flow, and the contribution rate of macropore flow in undisturbed soil column of 0 ~ 20 cm is 66.2%. The cumulative leaching amount of Br- accounted for 62.3% of the total leaching amount. For 20 ~ 40 cm, of non-tilling layer, the contribution rate of macroporous flow water conductivity is 0.22 ~ 1.7, while the proportion of Br- migration with macroporous flow is 14.5and 20.5. The results show that the phenomenon of macropore flow in tilling layer soil is much more significant than that in non-cultivated layer soil. 2) the results of PFSP show that the contribution of macroporous flow to the extension of the penetrating curve is the largest, the exchange migration between the two regions is the second, and the hydrodynamic dispersion is the least. That is, the larger the PFSP value, the greater the contribution of macroporous flow to the total water flux.
【作者单位】：中国科学院成都山地灾害与环境研究所;四川省中医药科学院;
【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)
【分类号】：S152.7

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