Purpose

Biochar amendment is commonly applied to ameliorate soil environment and alleviate nitrous oxide (N₂O) emissions, while our understanding of biochar effects on microbial community and nitrogen transformation traits of orchard root region soil is limited.

Methods

We observed the composition and diversity of bacterial, fungal, and archaeal communities in apple root region (non-rhizosphere, rhizosphere, and rhizoplane) soils amended with apple wood biochar using the Illumina sequencing methods. We used quantitative PCR to quantify the abundance of nitrogen-transforming functional marker genes involved in microbial nitrogen fixation (nifH), nitrification (archaeal amoA and bacterial amoA), and denitrification (nirK, nirS, and nosZ).

Results

Biochar amendment altered bacterial, fungal, and archaeal community compositions in apple root region soil. When compared to control, biochar additions dramatically increased the α-diversity of bacteria in the rhizoplane soil, whereas amendment significantly decreased the α-diversity of fungi and archaea in the rhizosphere soil. Moreover, the driving factors varied in non-rhizosphere, rhizosphere, and rhizoplane soils. The abundance of nitrogen-fixing microorganisms and microbial N₂O reduction were enhanced by biochar amendment in rhizosphere and rhizoplane soils, which was associated with an observed reduction in N₂O concentrations by 13.7 and 35.1% in the 15- and 20-cm soil layer. However, wood biochar amendment had insignificant effect on nifH and amoA gene abundances in non-rhizosphere soil. Network analysis revealed that nitrogen-transforming functional genes had an intensive potential link to multiple microbial phyla.

Conclusions

The soil microbial community was altered in biochar-amended soil by changing soil properties, thereby regulating nitrogen transformation processes and N₂O concentrations in apple root region soil.

中文翻译：

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生物炭作用下苹果根际和根际土壤氮素转化和微生物群落结构变化

目的

生物炭改良剂通常用于改善土壤环境并减轻一氧化二氮（N ₂ O）排放，而我们对生物炭对果园根部土壤微生物群落和氮素转化特性的影响的理解是有限的。

方法

我们观察到的苹果根部土壤（非根际，根际和根际平面）的细菌，真菌和古细菌群落的组成和多样性，使用Illumina测序方法对苹果木生物炭进行了改良。我们使用定量PCR来量化参与微生物固氮（nifH），硝化作用（古细菌amoA和细菌amoA）和反硝化作用（nirK，nirS和nosZ）的氮转化功能标记基因的丰度。

结果

生物炭改良剂改变了苹果根区土壤中的细菌，真菌和古细菌群落组成。与对照相比，生物炭的添加显着增加了根际土壤中细菌的α多样性，而改良剂显着降低了根际土壤中真菌和古细菌的α多样性。而且，驱动因素在非根际，根际和根际土壤中也不同。根际和根际土壤中的生物炭改良提高了固氮微生物的丰度和减少了微生物的N ₂ O含量，这与在15厘米和20厘米土壤中观察到的N ₂ O浓度降低了13.7％和35.1％有关。层。但是，木材生物炭修正物对nifH和非根际土壤中的amoA基因丰富。网络分析表明，氮转化功能基因与多种微生物门有密切的潜在联系。

结论

通过改变土壤性质改变了生物炭改良过的土壤中的微生物群落，从而调节了苹果根区土壤中的氮转化过程和N ₂ O浓度。