Purpose

Iron (Fe) oxides play an important role in regulating nitrification and N₂O emissions, but there is very little study on the biological-chemical comprehensive effects of Fe oxides on nitrification and N₂O emissions.

Materials and methods

A laboratory incubation experiment was performed to evaluate the effect of goethite addition on nitrification and N₂O emissions from acidic and alkaline paddy soils.

Results and discussion

The cumulative N₂O emissions from alkaline paddy soil were significantly higher than those from acidic paddy soil, no matter whether goethite had been added or not. Adding goethite decreased the average net rate of soil nitrification in acidic paddy soil by 33.2% in comparison with the treatment without adding goethite; however, adding goethite scarcely decreased the average net rate in alkaline paddy soil. Adding goethite increased the maximal N₂O emissions by 85.6% in alkaline paddy soil, but had no obvious effect in acidic paddy soil. Adding goethite significantly increased the abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) amoA genes in both alkaline and acidic paddy soils. High-throughput pyrosequencing of 16S rRNA gene showed that adding goethite significantly increased the relative abundance of Nitrosomonadaceae in alkaline paddy soil and that the dominant species of AOB and AOA were Nitrosomonadaceae and Nitrososphaeraceae, respectively.

Conclusions

N₂O emissions in alkaline paddy soil were higher than those in acidic paddy soil. The enhancement of N₂O emissions by goethite was more significant in alkaline paddy soil than in acidic paddy soil. Goethite stimulated the abundance of amoA gene (both of AOB and AOA) and participated in nitrification process via chemical reaction with intermediates.

中文翻译：

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针铁矿添加对水稻土一氧化二氮排放的生物化学综合影响

目的

铁（Fe）氧化物在调节硝化和N ₂ O排放中起重要作用，但是关于铁氧化物对硝化和N ₂ O排放的生化综合效应的研究很少。

材料和方法

进行了实验室培养实验，以评估针铁矿添加对酸性和碱性稻田土壤硝化和N ₂ O排放的影响。

结果和讨论

不论是否添加针铁矿，碱性水稻土的累积N ₂ O排放量明显高于酸性水稻土。与不添加针铁矿的处理相比，添加针铁矿可使酸性水稻土的土壤硝化平均净速率降低33.2％；但是，添加针铁矿几乎不会降低碱性稻田土壤的平均净含量。添加针铁矿可使碱性水稻土的最大N ₂ O排放量增加85.6％，但对酸性水稻土没有明显的影响。添加针铁矿显着增加了氨氧化古细菌（AOA）和细菌（AOB）amoA的丰度碱性和酸性水稻土中的基因 高通量16S rRNA基因的焦磷酸测序表明，加入针铁矿显著上升的相对丰度Nitrosomonadaceae在碱性水稻土和AOB和AOA的优势种为Nitrosomonadaceae和Nitrososphaeraceae分别。

结论

碱性水稻土的N ₂ O排放量高于酸性水稻土。碱性稻田土壤中针铁矿对N ₂ O排放的增强作用大于酸性稻田土壤。针铁矿刺激了amoA基因的丰富（AOB和AOA都存在），并通过与中间体的化学反应参与硝化过程。