Purpose

Biochars have considerable potential to improve soil organic carbon (SOC) sequestration and consequently regulate greenhouse gas emissions. However, the important roles of microbial mediation in the biochar-induced SOC accumulation over the plant growth season have not been adequately explored. Here, we illustrated the interactive effects of biochar amendments and plant growth stages on the microbial community and SOC mineralisation.

Materials and methods

A 3-year experiment was performed in a tobacco (Nicotiana tabacum L.) field with five treatments, including no fertilisation, conventional fertilisation, and conventional fertilisation with three rates of biochar amendments.

Results and discussion

Biochar amendments significantly improved soil moisture capacity (SMC) but decreased nitrogen (N) availability. The bacterial and fungal biomasses were enriched under biochar amendments and at the rosette and vigorous stages of the crop growing season. Biochar amendments and plant growth stages substantially affected the microbial community structure, as determined by the ratios of bacteria to fungi (B/F) and Gram-positive bacteria to Gram-negative bacteria (GP/GN). Random forest modelling revealed that SMC and N availability were the important predictors of microbial community and SOC mineralisation. Structural equation modelling indicated that microbial biomass and community structure (the rations of B/F and GP/GN) were positively associated with SMC but negatively correlated with N availability. Microbial community structure was more influential than microbial biomass in reducing microbial carbon metabolism of carbohydrates (cellobiose, glucose, and xylose) and SOC mineralisation.

Conclusions

Our study provided insights into the functional role of the microbial community in the biochar-induced negative priming effect on SOC mineralisation during the plant growth stages.

中文翻译：

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通过改变植物生长期的微生物群落结构，生物炭对土壤有机碳矿化产生负向激发作用

目的

生物炭具有改善土壤有机碳（SOC）隔离并因此调节温室气体排放的巨大潜力。然而，尚未充分探讨微生物介导在植物生长季中生物炭诱导的SOC积累中的重要作用。在这里，我们说明了生物炭改良剂和植物生长阶段对微生物群落和SOC矿化的相互作用。

材料和方法

在烟草（Nicotiana tabacum L.）田间进行了为期3年的实验，采用了5种处理方法，包括不施肥，常规施肥和采用三种生物炭修正率的常规施肥。

结果和讨论

生物炭的改良剂显着改善了土壤水分容量（SMC），但降低了氮（N）的利用率。细菌和真菌生物量在生物炭改良剂下以及农作物生长季节的玫瑰花结和旺盛阶段富集。生物炭的改良剂和植物的生长阶段极大地影响了微生物群落结构，这取决于细菌与真菌的比例（B / F）和革兰氏阳性细菌与革兰氏阴性细菌的比例（GP / GN）。随机森林模型显示，SMC和N的有效性是微生物群落和SOC矿化的重要预测因子。结构方程模型表明，微生物的生物量和群落结构（B / F和GP / GN的比例）与SMC呈正相关，而与N的利用率呈负相关。

结论

我们的研究提供了关于微生物群落在植物生长阶段生物炭诱导的SOC矿化的负引发作用中的功能性作用的见解。