主成分分析方法在长期施肥土壤质量评价中的应用

以长期定位试验玉米季成熟期6种土壤微生物活性和9种土壤化学性质指标组成的土壤生物肥力性质为评价指标对不同施肥条件下的土壤质量水平进行主成分分析。结果表明，经18年连续不同施肥处理后，各土壤性质在处理间均产生显著差异，但各土壤性质在处理间的变化趋势并不完全一致。上述15个土壤性质指标最终可以用两个主成分来综合表征土壤质量，其中有机C、全N、碱解N、pH值、微生物生物量C、微生物生物量N、脲酶、转化酶、FDA酶和脱氢酶活性等10个土壤性质在第一主成分（PC1）上有较高因子负荷；全P、全K、速效N和速效P在第二主成分（PC2）上有较高的因子负荷。同时各施肥土壤质量水平在主成分1上的分异程度大于主成分2。根据两个主成分的综合得分结果显示，长期不同施肥土壤质量水平高低依次表现为OM＞1/2OM＞NPK＞NP＞PK＞NK＞CK。

Application of principal component analysis in evaluation of soil quality under different long-term fertilization

Based on the experimental platform of Long-term Fertilization Test in the State Experimental Station for Agro-ecology in Fengqiu, Chinese Academy of Sciences, in this research the comprehensive soil quality was evaluated by the indicators of soil microbial activity and soil chemistry properties through principal component analysis. The results indicated that soil properties significantly differed with incomplete patterns among fertilization regimes. Soil quality could be revealed by two principal components through 15 soil properties which consisted of 10 soil properties with high factorial loads in the first component (PC1) including soil organic C, total N, alkali-hydrolyzable N, pH, microbial biomass C, microbial biomass N and activities of urease, invertase, FDA and dehydrogenase, and the rest with high factorial loads in the second one (PC2) including soil total P, total K, available N and P. The variation of soil quality was higher in PC1 than in PC2. Judging from the integrated scores of the both principal components, the highest soil quality displayed in OM, then followed the sequence of 1/2OM, NPK, NP, PK, NK and CK.