基于聚类及PCA分析的羌活栽培区土壤质量评价

Soil quality evaluation of Notopterygium incisum cultivation areabased on cluster and PCA analysis

为了准确评价川产道地药材羌活栽培区耕作层土壤质量状况,分别采用聚类分析法(CA)和主成分分析法(PCA)构建栽培区耕作层土壤质量最小数据集(minimum data set,MDS),利用最小数据集土壤质量指数(soil quality index-CA,SQI-CA和SQI-PCA)和全量数据集土壤质量指数(SQI-T)评价川西北羌活栽培区耕作层土壤质量。结果表明:(1)羌活栽培区土壤有机质含量为(19.14±6.75)g·kg^(−1),处于中度贫瘠化水平;土壤速效氮、速效磷和速效钾含量较高,分别为(129.78±47.78)mg·kg^(−1)、(22.89±14.78)g·kg^(−1)和(159.87±97.87)mg·kg^(−1);土壤为中性土壤,pH均值为7.20±1.68。(2)基于不同数据集的土壤质量指数均值排序为SQI-T>SQI-PCA>SQI-CA,而SQI-PCA与SQI-T之间的Nash有效系数高于SQI-CA,相对偏差系数低于SQI-CA,说明基于主成分分析的最小数据集(MDS-PCA)评价效果更优,该数据集包括土壤容重、抗剪强度、有机质含量、饱和导水率、黏粒含量、pH、速效氮和砂粒含量共8个指标。(3)川西北羌活栽培区土壤质量指数SQI-PCA<0.33,表明该研究区耕作层土壤质量总体水平较差,主要体现在土壤紧实、有机质含量低,需要通过合理耕作、施肥和土壤改良等方式对耕作层土壤质量进行有效调控。研究结果可为川西北高原羌活栽培区土壤质量改良和生产适宜性调控提供参考,有利于川西北高原区中药材产区土壤可持续利用。

In order to accurately assess the soil quality of Notopterygium incisum cultivation area in the northwest Sichuan Province,this study established the MDS quality indices of cultivated layer(0−20 cm)for N.incisum cultivation area based on both cluster analysis(CA)and principal component analysis(PCA).Three soil quality indices(SQIs),including SQI-T(total dataset),SQI-CA(dataset from CA analysis)and SQI-PCA(dataset from PCA analysis),were identified by measurements of soil physical and chemical properties.The results showed that:(1)for all studied sites,the soil organic matter content(SOM)was(19.14±6.75)g·kg^(−1) which was in moderately barren level,and the contents of soil available nitrogen,phosphorus and potassium were(129.78±47.78)mg·kg^(−1),(22.89±14.78)g·kg^(−1) and(159.87±97.87)mg·kg^(−1),respectively.The soil was neutral with a pH average of 7.20±1.68.(2)The variation range and the mean of soil quality index based on 3 different data sets were in order of SQI-T>SQI-PCA>SQI-CA.Furthermore,the relevance and Nash efficiency coefficient between SQI-PCA and SQI-T were both higher than that between SQI-CA and SQI-T,and the relative deviation coefficient between SQI-PCA and SQ-T were lower than that between SQI-CA and SQI-T,which illustrated a higher availability of MDS-PCA(MDS based on PCA)than MDS-CA(MDS based on CA)for soil quality assessment in studied area included eight properties:bulk density,soil shear strength,soil organic matter,soil saturated water conductivity,clay,pH,available nitrogen and sand content.(3)The soil quality index(SQI-PCA)in studied soil was lower than 0.33,indicating a deterioration of soil quality in N.incisum cultivation area in Sichuan province.In order to maintain the soil sustainability,rational tillage,reasonable fertilization and soil improvement practice should be considered in future soil management.The results suggested that soil quality plays a significant role in determining the yield quality of medicinal plants.The findings of this study can provide useful information not only for the soil quality recovery of the cultivated layer but also for the suitability soil management of N.incisum cultivation area in northwest Sichuan.