基于主成分-聚类分析的植烟土壤障碍因子诊断

Diagnosis of soil obstacle factors in flue-cured tobacco rotation system based on principal component analysis and cluster analysis

烤烟长期连作与过度施肥导致土壤障碍问题频发,病虫害增加,严重影响烟叶质量。通过对以烤烟为中心的不同作物轮作模式下土壤障碍因子识别与评价,探究烤烟轮作体系下土壤酶活性的响应规律,并建立障碍模型,对保障植烟土壤高质量、可持续发展经营具有重要意义。采集分析了丽江金沙江流域5县(区)植烟区大麦-烤烟(Ⅰ)、大蒜-烤烟(Ⅱ)、油菜-烤烟(Ⅲ)和蚕豆-烤烟(Ⅳ)主要轮作模式土壤典型样品111个,利用主成分分析法结合聚类分析法分析了19个土壤养分指标,从中挖掘主要障碍因子,并探究土壤酶活性的响应机制,同时引入障碍度模型对不同轮作模式下土壤养分因子进行定量化分析。结果表明:不同轮作模式下土壤主要障碍因子存在差异。大麦-烤烟(Ⅰ)模式中土壤障碍因子有4个,pH、全氮和水解性氮均属土壤重度障碍因子,有机质属轻度障碍,障碍度为8.29%。大蒜-烤烟(Ⅱ)模式中,有效磷和有效锌障碍度分别为5.67%和9.98%,均属于轻度障碍;水解性氮、交换性镁和有效铁障碍度分别为42.34%、28.41%和19.28%,属于重度障碍。油菜-烤烟(Ⅲ)模式中,有机质、全氮、水解性氮和交换性镁等土壤障碍因子均属重度障碍,障碍度从大到小依次排列为:有机质(45.95%)>全氮(38.82%)>水解性氮(34.23%)>交换性镁(22.61%)。蚕豆-烤烟(Ⅳ)模式中,有机质和有效铁属轻度障碍,障碍度分别为4.12%和8.33%,交换性镁属重度障碍,障碍度为38.30%。土壤化学指标与酶活性相关性分析表明:土壤过氧化氢酶活性与土壤有机质、全氮、水解性氮、有效磷、有效铁存在显著正相关关系(P<0.05);与土壤pH、交换性镁存在显著负相关关系(P<0.05)。土壤脲酶活性与交换性镁存在显著正相关关系,与有效铁和过氧化氢酶活性存在显著负相关关系(P<0.05)。由于烤烟施用配方肥料,因此,该研究区4种不同轮作模式土壤的大量元素供应充分,土壤障碍集中表现为土壤酸化、低氮,部分中、微量元素缺失等共性问题。在烤烟种植管理中,针对不同前茬作物应当制定不同施肥方案,因地制宜,减少土壤障碍的发生。

Long-term continuous cropping and excessive fertilization of flue-cured tobacco caused frequent soil problems,increased pest and disease,and seriously affected the quality of tobacco leaves.Through the identification and evaluation of soil obstacle factors under different crop rotation modes centered on flue-cured tobacco,the response law of soil enzyme activity under flue-cured tobacco rotation system was explored,and the obstacle model was established,which is of great significance to ensure the high quality and sustainable development of tobacco soil management.111 typical soil samples under the rotation patterns of barley-flue-cured tobacco(Ⅰ),garlic-flue-cured tobacco(Ⅱ),rapeseed-flue-cured tobacco(Ⅲ)and broad bean-flue-cured tobacco(Ⅳ)were collected in 5 counties(districts)of Jinsha river basin,Lijiang city,and 19 soil nutrient index were analyzed using principal component analysis(pca)combined with clustering analysis method.The main obstacle factors and the response mechanism of soil enzyme activity were explored,and the obstacle degree model was introduced to quantitatively analyze soil nutrient factors under different crop rotation patterns.The results showed that there were differences in soil obstacle factors under different crop rotation patterns.In barley-flue-cured tobacco(Ⅰ)mode,four soil obstacle factors,including pH,total nitrogen and hydrolyzed nitrogen,were the severe obstacle factors,and organic matter was the mild obstacle factor,with an obstacle degree of 8.29%.In garlic-flue-cured tobacco(Ⅱ)mode,the obstacle degree of available phosphorus and available zinc were 5.67%and 9.98%,respectively,both belonging to mild impairment.The obstacle degree of hydrolyzed nitrogen,exchangeable magnesium and available iron were 42.34%,28.41%and 19.28%,respectively,which were serious.In rapeseed-flue-cured tobacco(Ⅲ)mode,the obstacle degree ranked as:organic matter(45.95%)>total nitrogen(38.82%)>hydrolyzed nitrogen(34.23%)>exchangeable magnesium(22.61%),and all of them were the major soil obstacles.In the broad bean-flue-cured tobacco(Ⅳ)mode,organic matter and available iron were mild,with an obstacle degree of 4.12%and 8.33%,respectively,while exchangeable magnesium was severe,with an obstacle degree of 38.30%.The correlation analysis between soil chemical indexes and enzyme activity showed that soil catalase activity was significantly positively correlated with soil organic matter,total nitrogen,hydrolytic nitrogen,available phosphorus and available iron(P<0.05).There was significant negative correlation with soil pH and exchangeable magnesium(P<0.05).Soil urease activity was significantly positively correlated with exchangeable magnesium,and significantly negatively correlated with available iron and catalase activities(P<0.05).Due to the application of formula fertilizer in flue-cured tobacco,the supply of large amounts of elements in the soil of four different crop rotation patterns was sufficient,and the common problems of soil acidification,low nitrogen and partial absence of medium and trace elements were concentrated in the study area.In the management of flue-cured tobacco planting,different fertilization schemes should be formulated according to the different stubble crops to reduce the occurrence of soil obstacles.