C:N 比值并不是人工调控 30 天后酸性土壤中 NO 产量的可靠预测指标。
C:N ratio is not a reliable predictor of NO production in acidic soils after a 30-day artificial manipulation.
机构信息
School of Geography, Nanjing Normal University, Nanjing 210023, China.
School of Geography, Nanjing Normal University, Nanjing 210023, China; Key Laboratory of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education, Nanjing 210023, China; Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing 210023, China.
出版信息
Sci Total Environ. 2020 Jul 10;725:138427. doi: 10.1016/j.scitotenv.2020.138427. Epub 2020 Apr 2.
To test the effect of C:N ratio on soil NO production, NO production rates and pathways associated with nitrification (AOA-amoA, AOB-amoA, fungal ITS rDNA, bacterial 16S rRNA), and denitrification-related (nirK, nirS, nosZ) genes were investigated in subtropical forest (SF) and cropland (SC) soil in China in a 30-day C:N ratio manipulation. In addition, 24-hour C:N ratio manipulation, including the addition of acetic acid, were conducted to verify the results observed in the 30-day experiment. After 30 days of manipulation, the NO production rates (NO) increased from 2.46 in CN23 treatment to 4.71 μg N kg day in CN 10 treatment in SF, while it decreased from 4.17 in CN23 treatment to 3.83 μg N kg day in CN10 treatment in SC. The results in 24-hour experiment were consistent with those in 30-day experiment, and the addition of acetic acid increased NO in SC, but not in SF. Soil C:N ratios and inorganic N (NH + NO) concentrations influenced the contribution of denitrification to NO production and the NO production rate via denitrification. Soil AOA played a dominant role in autotrophic nitrification-derived NO production, resulting in a high contribution of autotrophic nitrification under low pH. Therefore, pH instead of C:N ratio, is a key parameter for evaluating autotrophic nitrification-derived NO via AOA and AOB. Soil C:N ratio was significantly and positively correlated with the contribution of heterotrophic nitrification to NO production, while there was no significant correlation with the NO production rate via heterotrophic nitrification. This is mainly because the responsible heterotrophs (i.e., fungi and bacteria) were negatively and positively correlated with C:N ratio in SF and SC, respectively. Therefore, C:N ratio is not a strong predictor of soil NO production, the initial C or N content and composition of functional genes could provide key information in acidic soils after a 30-day artificial C:N ratio manipulation.
为了测试 C:N 比对土壤 NO 生成的影响，在中国亚热带森林（SF）和农田（SC）土壤中进行了为期 30 天的 C:N 比操纵实验，研究了与硝化作用（AOA-amoA、AOB-amoA、真菌 ITS rDNA、细菌 16S rRNA）相关的 NO 生成率和途径，以及与反硝化作用相关（nirK、nirS、nosZ）的基因。此外，还进行了 24 小时的 C:N 比操纵实验，包括添加乙酸，以验证 30 天实验中的结果。在 30 天的处理后，SF 中从 CN23 处理的 2.46μg N kg-1 day-1增加到 CN10 处理的 4.71μg N kg-1 day-1，而 SC 中从 CN23 处理的 4.17μg N kg-1 day-1减少到 CN10 处理的 3.83μg N kg-1 day-1。24 小时实验的结果与 30 天实验的结果一致，并且添加乙酸增加了 SC 中的 NO，但没有增加 SF 中的 NO。土壤 C:N 比和无机氮（NH+NO）浓度影响了反硝化作用对 NO 生成的贡献和反硝化作用的 NO 生成率。土壤 AOA 在自养硝化衍生的 NO 生成中起着主导作用，导致在低 pH 值下自养硝化作用的贡献很高。因此，pH 值而不是 C:N 比，是通过 AOA 和 AOB 评估自养硝化衍生的 NO 的关键参数。土壤 C:N 比与异养硝化作用对 NO 生成的贡献呈显著正相关，而与异养硝化作用的 NO 生成率之间没有显著相关性。这主要是因为在 SF 和 SC 中，负责的异养生物（即真菌和细菌）与 C:N 比呈负相关和正相关。因此，C:N 比不是土壤 NO 生成的有力预测因子，在经过 30 天的人工 C:N 比操纵后，功能基因的初始 C 或 N 含量和组成可以为酸性土壤提供关键信息。
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