Responses of N2O Production and Abundances of Associated Microorganisms to Soil Profiles and Water Regime in Two Paddy Soils

Agronomy

Anguo Tu¹  Minghao Mo¹  Jichao Zuo¹  Qingling Fu²  Jun Zhu²  Hongqing Hu²  Heng Zheng² 

[1] Jiangxi Provincial Key Laboratory of Soil Erosion and Prevention, Jiangxi Academy of Water Science and Engineering, Nanchang 330029, China;Key Laboratory of Subtropical Agricultural Resource and Environment, Ministry of Agriculture and Rural Affairs, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China;

关键词: nitrification;    denitrification;    iron oxides;    nitrifying and denitrifying microorganisms;    hydromorphic and gleyed paddy soils;   

DOI  :  10.3390/agronomy12030743

来源: DOAJ

【 摘 要 】

Soil moisture is one of the critical factors affecting N₂O emissions. The water regime affects the physical and chemical properties of paddy soil in different soil layers, which, in turn, affects N₂O emissions and microbial growth. However, there are few reports on the effects of different soil layers and soil moisture conditions on N₂O emission characteristics and microbial mechanisms. A 21-day microcosm experiment was performed to research the effects of soil moisture levels (60%, 100%, and 200% water holding capacity, WHC) and different soil layers (0–10, 10–20, and 20–40 cm) on N₂O emissions in hydromorphic and gleyed paddy soils. Function microbes involved in nitrification and denitrification were determined by quantitative PCR. Moreover, the abiotic variables pH, Eh, and exchangeable Fe²⁺, Fe³⁺, NH₄⁺-N, and NO₃⁻-N were also analyzed. Results showed that N₂O emissions of gleyed paddy soil were significantly higher than that of hydromorphic paddy soil, which was consistent with the result of the abundance of nitrifier and denitrifier in the two paddy soils. Soil depth, water content, and their interaction significantly affected N₂O emission (p < 0.05). Cumulative emissions of N₂O from each layer of the two paddy soils at 100% and 200% WHC were significantly higher than that under 60% WHC (p < 0.05). N₂O emissions decreased significantly with the increase of soil depth (p < 0.05), which was consistent with the change in the abundance of soil nitrifier (AOB and AOA) and denitrifier (nirK and nosZ) function genes with soil depth. The abundance of AOB, AOA, and nirK and nosZ genes decreased significantly with soil depth (p < 0.05), but did not respond significantly to the water regime. Based on the results of redundancy analysis, the contents of Fe²⁺ and Fe³⁺ were positively correlated with N₂O emissions and the abundance of AOB, AOA, and nirK and nosZ genes. These results indicate that N₂O emissions and the abundance of associated microbes are selectively affected by soil moisture and soil layers in the two paddy soils.

【 授权许可】

Unknown