Aims

Soil fungal communities play pivotal roles in promoting ecosystem carbon (C) and nitrogen (N) cycling, stimulating disease resistance and enhancing tolerance against salt stress of host plants. However, the impact of anthropogenic management practices on the soil fungal community structure has not yet been clarified.

Methods

Using a four-consecutive-year field experiment and the quantitative polymerase chain reaction (qPCR) and Illumina MiSeq DNA sequencing methods, the single and interactive impacts of crop cultivation (CK), N fertilization (N) and fulvic acid (F) on soil fungal diversity, abundance, composition and functional groups were investigated.

Results

Consecutive crop cultivation improved soil chemical and microbial properties by reducing soil electrical conductivity (EC_e) and enhancing soil organic carbon (SOC), microbial biomass carbon (MNC), and microbial biomass nitrogen (MBN). Crop cultivation had larger contribution to fungal richness and diversity than N fertilization and fulvic acid. Crop cultivation enriched mycorrhizal fungi and N fertilization enriched endophytic, saprophytic and pathogenic fungi. Structural equation modeling (SEM) revealed that soil EC_e and pH indirectly influenced MBN through their adverse direct impact on OTUs, Shannon index and abundance of predominant fungal taxa. N input exhibited a positive indirect influence on MBN through enhancing abundance of Funneliformis at the genus level.

Conclusions

Crop cultivation, N input, and fulvic acid addition in saline soil environment changed the environmental niches and drove the evolution of soil fungal community. In return, the shifts in soil fungal community composition and functional groups greatly affected soil C and N transformation with potential feedback on soil microbial activity.

中文翻译：

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盐胁迫冲积潮土中作物栽培，氮和黄腐酸对土壤真菌群落结构的影响

目的

土壤真菌群落在促进生态系统碳（C）和氮（N）循环，刺激抗病性和增强对寄主植物盐胁迫的耐受性方面发挥关键作用。但是，人为管理措施对土壤真菌群落结构的影响尚未阐明。

方法

通过连续四年的野外试验以及定量聚合酶链反应（qPCR）和Illumina MiSeq DNA测序方法，研究了农作物种植（CK），氮肥（N）和黄腐酸（F）对土壤的单一和相互作用影响研究了真菌的多样性，丰度，组成和功能基团。

结果

连续作物栽培通过降低土壤电导率（EC _e）和增强土壤有机碳（SOC），微生物生物量碳（MNC）和微生物生物量氮（MBN）改善了土壤化学和微生物特性。与氮肥和黄腐酸相比，作物栽培对真菌的丰富性和多样性的贡献更大。作物种植增加了菌根真菌，而氮肥则增加了内生，腐生和致病真菌。结构方程模型（SEM）显示，土壤EC _e和pH通过对OTU，香农指数和主要真菌类群数量的不利直接影响而间接影响MBN。氮输入通过增强漏斗菌的丰度对MBN表现出积极的间接影响 在属水平上。

结论

盐碱土壤环境中的农作物种植，氮素输入和黄腐酸的添加改变了环境生态位，推动了土壤真菌群落的进化。作为回报，土壤真菌群落组成和官能团的变化极大地影响了土壤碳和氮的转化，并对土壤微生物活性产生了潜在的反馈。