不同绿肥腐解对烟田土壤有效磷含量影响的微生物机制

Deciphering Microbial Mechanism Underlying Changes of Available Phosphorus Content in Tobacco-planting Soils During Different Green Manure Decomposition

为阐明绿肥还田提高土壤有效磷含量的机制,针对贵州植烟土壤,选取光叶苕子、油菜和黑麦草3种绿肥为供试材料,通过微宇宙试验,研究了添加3种绿肥恒温培养30 d后土壤中有机酸含量、土壤微生物群落功能以及磷酸酶活性的变化。结果表明:3种绿肥腐解均显著提升了植烟土壤有效磷含量、微生物代谢活性强度(AWCD)和磷酸酶活性,特别是光叶苕子处理对上述指标的提升最为显著。同时,光叶苕子处理中有机酸总量,特别是柠檬酸的含量显著高于其他处理。随机森林分析和结构方程模型结果显示,AWCD、磷酸酶活性以及有机酸含量是影响土壤有效磷含量的关键因子,其中AWCD的提高可以直接促进土壤中有效磷含量的提升;此外,AWCD还可以通过影响磷酸酶的活性和有机酸的含量影响土壤中有效磷的含量,其中微生物代谢活性通过促进磷酸酶活性从而提高土壤有效磷含量是土壤磷素有效性提升的首要途径。

An incubation experiment was conducted using soils taken from tobacco-planting filed in Liupanshui City of Guizhou to explore the effects of green manure incorporation on soil phosphorus availability and its underlying microbial mechanism.Three types of green manure,vetch,rape and ryegrass were selected as exogenous organic materials and incorporated into tested soils.After 30 days of incubation,soil samples were taken to analyze organic acid content,microbial community function and phosphatase activity.The results showed significant increases in available phosphorus content,average well color development(AWCD)and phosphatase activity under green manure treatments compared with the control treatment,among which vetch had the highest enhancements.In addition,the total amount of organic acids,especially citric acid content was significantly higher under vetch treatment than under other treatments.Random forest analysis and structural equation model results indicated that AWCD,phosphatase activity and organic acids concentrations were the key factors regulating available phosphorus content,among these factors AWCD showed direct effect,and moreover,AWCD also indirectly affected available phosphorus content via influencing soil phosphatase activity and organic acids concentrations of which promoting phosphatase activity by microbial activity was the primary pathway to improve soil phosphorus availability.