Aims

The stability of soil organic matter (SOM) is influenced by its chemical structure as well as by biological and environmental factors. However, the specific mechanisms by which pore space gaseous O₂/CO₂ concentrations affect SOM are not well understood.

Methods

The experimental design involved a 2 (Chinese photinia planted and bare land) × 2 (O₂ aeration levels) × 2 (CO₂ aeration levels) design compared to 2 non-aeration treatments, to investigate the impact of pore space O₂/CO₂ concentration on soil enzymes, soil organic carbon (SOC), light fraction organic carbon (LFOC), dissolved organic carbon (DOC) and microbial carbon (MBC).

Results

The injection of 21% O₂ led to a significant increase in the activities of catalase, urease, saccharase, invertase, and polyphenol oxidase enzymes. Significant increases in the contents of SOC, LFOC, DOC, and MBC were observed when comparing the effects of injecting 21% O₂ into the soil with 15% O₂, with the differences between treatments on carbon turnover rate increasing over time. Additionally, vegetation treatments were observed to increase DOC, MBC, and SOC. Changes in pore space gaseous CO₂ concentration from 0.03% to 0.4% had no significant effect on soil microorganisms, soil enzymes, or SOC turnover.

Conclusions

This study demonstrates that higher concentrations of pore space gaseous O₂ stimulate the activity of soil microorganisms, affecting the carbon turnover rate and its stability. These findings provide important evidence of SOC responses to variations in pore space gaseous O₂.

中文翻译：

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棕色森林土壤中土壤有机碳周转受土壤孔隙空间O2浓度控制

 目标

土壤有机质（SOM）的稳定性受到其化学结构以及生物和环境因素的影响。然而，孔隙空间气态O ₂ /CO ₂浓度影响SOM的具体机制尚不清楚。

 方法

实验设计采用2（种植石楠和裸地）×2（O ₂通气水平）×2（CO ₂通气水平）设计与2种不通气处理进行比较，以研究孔隙空间O ₂ /CO的影响₂土壤酶、土壤有机碳（SOC）、轻组分有机碳（LFOC）、溶解有机碳（DOC）和微生物碳（MBC）的浓度。

 结果

注射21%O ₂导致过氧化氢酶、脲酶、蔗糖酶、蔗糖酶和多酚氧化酶的活性显着增加。当比较向土壤中注入21% O ₂和15% O ₂的效果时，观察到SOC、LFOC、DOC和MBC含量显着增加，并且处理之间的碳周转率差异随着时间的推移而增加。此外，还观察到植被处理会增加 DOC、MBC 和 SOC。孔隙空间气态CO ₂浓度从0.03%变化到0.4%对土壤微生物、土壤酶或SOC周转没有显着影响。

 结论

本研究表明，较高浓度的孔隙空间气态O ₂会刺激土壤微生物的活性，影响碳周转率及其稳定性。这些发现提供了 SOC 对孔隙空间气态 O ₂变化的响应的重要证据。