土壤分层关键因子确定——以新乡实验农地为例

Determining key factors for soil stratification:A case study in the farmland of Xinxiang

层状土壤是普遍存在的一种土壤结构,提取出表征土壤层次的关键因子有助于简单准确地划分土壤的层次。在河南省新乡农田挖掘了实测剖面(160 cm厚),通过野外观测和室内分析,获取了土壤质地,以及容重、饱和含水量、饱和导水率、滞留含水量和非毛管孔隙度等土壤水分运动因子的取值。通过对这些因子进行特征分析、系统聚类分析和主成分分析,将土壤分成0~50 cm、50~80 cm、80~140 cm和140~160 cm四个基本层次,得到滞留含水量】饱和含水量】饱和导水率】土壤容重】非毛管孔隙度的土壤分层因子的重要性次序并验证了文中分层方法具有鲁棒性(Robust)。这些结果将为土壤水分运动模拟提供科学依据。

Multi-layered soil is a ubiquitous soil structure in the soil profile. The key factors to divide multi- layered soil were discovered, which is of great significance to simply and accurately determine layered soil stratification. In this paper, a measured profile was dug in Xinxiang city, Henan province, whose depth was 160 cm. Meanwhile, lots of field observation and laboratory analyses were done on the soil samples collected in the profile. Then we obtained a number of soil hydraulic and physical parameters, including soil texture, soil bulk density, saturated soil moisture, saturated hydraulic conductivity, residual moisture and noncapillary porosity. By using correlation analysis, systematic cluster analysis and principal component analysis of the factors obtained in the profile, it is indicated that the soil profile(0-160 cm) can be divided into four layers: 0-50 cm, 50-80 cm, 80-120 cm and 120-160 cm. The importance order of the factors to divide the layered soil is: residual moisture > saturated water content > saturated hydraulic conductivity > soil bulk density> non- capillary porosity. In the discussion, the method of soil layer classification is robust. Therefore, the results obtained in this paper would provide scientific guideline for the numerical model of multi- layered soil moisture equation.