北方农牧交错带表层土壤孔隙度特征及其影响因素

Characteristics and influence of topsoil porosity in the northern agro-pastoral ecotone

本研究以张家口地区为研究区,分析农牧交错带土壤表土孔隙度特征及其影响因素。结果表明:土壤表土具有良好孔隙特征,土壤总孔隙度为42.6%,毛管孔隙度为24.6%,非毛管孔隙度为18.0%,毛管孔隙度占总孔隙度比重为56.8%,非毛管孔隙度比重为43.2%;土壤总孔隙度在不同地貌单元差异显著,表现为坝下区域(44.69%)>坝上高原(39.98%)(P<0.05),土壤孔隙度在不同土地利用和土壤类型之间差异均不显著(P<0.05);研究区整体看,土壤孔隙度与土壤理化参数显著相关(P<0.05),但分类型区域看,主要在地势相对平坦的坝上高原二者存在显著相关关系(P<0.05);总体来看,土壤孔隙度决定了土壤持水能力,与土壤质地、有机碳和容重仅在某些分类型区域存在相关关系。

In the present study,Zhangjiakou city was selected as the study area,and the characteristics of soil porosity in the northern agro-pastoral ecotone,and the factors influenced by these characteristics,were analyzed.The results demonstrate that the topsoil porosity in the study area is suitable for plant growth due to critical maximum porosity values and the ratios between capillary and non-capillary porosity.The maximum porosity of the topsoil was around 42.6%,the capillary porosity was around 24.6%,and the non-capillary porosity is about 18.0%.The ratio between capillary and non-capillary porosity was around 57∶43.The maximum porosity of the topsoil was significantly different between the Bashang Plateau and Baxia areas(P<0.05),with values of 39.98% and 44.69%,respectively.However,there were no significant differences in maximum porosity,capillary porosity,or non-capillary porosity between land use types or soil types(P<0.05),implying that the spatial distribution of topsoil porosity in Zhangjiakou city was mostly affected by landform factors.At the whole study area scale,topsoil porosity was correlated with soil quality parameters such as soil bulk density,soil organic carbon,soil water capacity,and sand,silt,and clay contents(P<0.05).However,considering the influential factors in different areas,topsoil porosity was mostly correlated with soil quality parameters in the Bashang Plateau(P<0.05),but was not correlated with soil quality parameters in single region of land use types or soil types.In general,the topsoil porosity mostly affected soil water capacity in Zhangjiakou City,and had a weak influence on other soil quality parameters.