不同施肥模式和地下水位条件下红壤水稻土PLFA指纹特征

摘要

Soil microbial community is an important indicator for assessing changes in soil quality, fertility and soil environment.Fertilization and groundwater table are two factors that may affect soil fertility and micro-environment.However, so far little has been reported on influence of groundwater table on soil microbial community, especially the joint effects of fertilization and groundwater table on soil microbial community.Phospholipid fatty acids (PLFA) analysis was conducted to evaluate impacts of fertilization and groundwater table on the soil microbial community in a red soil rice paddy.Results show that groundwater table significantly influenced soil pH, Eh,p (oxido-reduction potential in drained soil) and NO3-content, while soil fertilization did significantly soil Eh,y (oxido-reduction potential in flooded soil), Eh,p, total organic carbon, total N and available K contents.Besides, groundwater table significantly affected contents of total PLFA, bacterial PLFA, and Gram-positive (G+) bacterial PLFA and G+ PLFA/G-PLFA ratio while fertilization did significantly content of Gram-negative (G-) bacterial PLFA contents and G+ PLFA/G-PLFA ratio of the soil microbial community.Stepwise regression analysis shows that soil pH and total nitrogen content significantly affected actinomycete PLFA content, and soil pH did significantly contents of G+ bacterial PLFA, aerobic and anaerobic bacterial PLFA, too; soil Eh,y did significantly fungal to bacterial PLFA ratio; and contents of NO3--N and total K nitrogen did significantly G+ PLFA/G-PLFA ratio.PCA analysis shows that the environmental factors significantly affected soil microbial structure, total K, pH and Eh,y of the soils under long-term fertilization and varying groundwater table, thus making Treatment LNOM different from the other treatments, while NO3--N, total N and total P contents were the important factors making Treatments HNOM, HHOM, LCF, HCF and LHOM different from each other in microbial community.Obviously long-term fertilization and groundwater table significantly affect physiochemical properties and soil microbial community in the soil.%土壤微生物群落是评估土壤质量、衡量土壤肥力和指示土壤环境变化的重要指标.施肥和地下水位均会引起土壤养分和微环境发生变化,但地下水位对土壤微生物群落影响的研究尚鲜有报道,特别是施肥和地下水位管理双因素协同作用对土壤微生物群落的影响还不清楚.采用磷脂脂肪酸(PLFA)指纹图谱法研究长期施肥和不同地下水位条件下红壤水稻土微生物群落.结果表明,不同地下水位管理显著影响土壤pH值、Eh,p(排水状态下的氧化还原电位)和NO3--N含量,不同施肥模式显著改变土壤Eh,y(淹水状态下的氧化还原电位)、Eh,p、有机碳含量、全氮含量和速效钾含量.不同地下水位显著影响土壤总PLFA、细菌PLFA、G+ PLFA含量及G+ PLFA /G-PLFA比值,如高地下水位土壤G+ PLFA /G-PLFA比值(040~051)明显低于低地下水位土壤(040~194);不同施肥模式显著影响G-PLFA含量和G+ PLFA /G-PLFA比值,如施有机肥土壤G+ PLFA /G-PLFA比值(040~194)明显高于施化肥土壤(040~046).逐步回归分析显示放线菌PLFA含量显著受土壤pH值及全氮含量的影响,G+、厌氧菌、好氧菌PLFA含量显著受土壤pH值的影响,真菌PLFA/细菌PLFA比值显著受土壤Eh,y的影响,G+ PLFA /G-PLFA比值显著受NO3--N含量和全钾含量的影响.主成分分析显示环境因子影响了长期施肥和不同地下水位条件下红壤水稻土微生物群落结构,全钾含量、pH值和Eh,y是导致LNOM处理与其他处理间微生物群落结构不同的主要环境因子,而NO3--N含量、全氮含量、全磷含量是导致LHOM处理与HNOM、HHOM、LCF、HCF处理间微生物群落结构不同的主要环境因子.可见,长期施肥和地下水位管理显著影响红壤水稻土理化性质及微生物群落.