Abstract: In order to apply fertilizer rationally and reduce environmental pollution,Xichuan County in Danjiangkou Reservoir area was used as the research area to evaluate the nutrient indexes of 160 farmland surface soils by using principal component analysis and cluster analysis.The results showed that most of farmland soils in Xichuan County was acidic;the average values of the soil organic matter content,total nitrogen content,total phosphorus content,and total potassium content were 16.96,1. 22,0.50,and 16.21 g/kg,respectively.The overall fertility of the soil was at a medium level.The content of alkalihydrolyzable nitrogen and available phosphorus was low,belonging to lack or low-medium level.Through principal component analysis, the cumulative contribution rate of the two principal components was 53.289%.The main factors affecting the comprehensive evaluation of soil fertility were organic matter content,total nitrogen content, alkali-hydrolyzable nitrogen content and pH value, and through further division of soil fertility level,the comprehensive level of soil fertility quality was divided into categories Ⅰ,Ⅱ and Ⅲ,which represented high,medium and low soil fertility levels respectively.Among them,the soils in the Ⅱ and Ⅲ grades accounted for 56.25% and 38.75% of the total samples respectively.The soil fertility quality of farmland in Xichuan County was low.

Key words: Principal component, Hierarchical cluster analysis, Soil nutrient, Evaluation

摘要： 为了合理施肥，减少生态环境污染，以丹江口库区淅川县为研究区域，采用主成分分析和聚类分析法对160份农田表层土壤养分指标进行评价。结果表明：淅川县农田大部分土壤为酸性；土壤的有机质、全氮、全磷、全钾含量的平均值分别为16.96、1.22、0.50、16.21 g/kg，土壤肥力整体处于中等水平，其中碱解氮和有效磷含量较低，属于缺乏或中低水平。通过主成分分析得出2个主成分的累计贡献率为53.289%，影响土壤肥力综合评价状况的主要因素有机质含量、全氮含量、碱解氮含量和pH值，进一步对土壤肥力等级进行划分，将土壤肥力质量综合水平分为Ⅰ、Ⅱ、Ⅲ级，分别代表土壤肥力高、中、低水平，其中在Ⅱ、Ⅲ级的土壤分别占总样本数的56.25%、38.75%，淅川县农田土壤肥力总体质量水平偏低。

关键词: 主成分, 聚类分析, 土壤养分, 评价