Linking the potential activities of methanogens and methanotrophs to their communities under different fertilization regimes in coastal saline paddy soils

• Published in: Applied soil ecology : a section of Agriculture, ecosystems & environment ecosystems & environment, 2023-12, Vol.192, p.105102, Article 105102
• Main Authors: Dai, Xianglin, Sun, Jianping, Zhao, Zijing, Ma, Ruiping, Zheng, Zhenyu, Liu, Yahui, Wang, Xiubin, Zhou, Wei
• Format: Article
• Language: English
• Subjects: Co-occurrence pattern; Keystone taxa; Methanogen; Methanotroph; Nitrogen fertilizer reduction; Straw or biochar returning
• ISSN: 0929-1393; 1873-0272
• DOI: 10.1016/j.apsoil.2023.105102

Methane (CH4) emissions are primarily dependent on the net balance between the activities of methanogens and methanotrophs. Straw returning (straw residue incorporation) and nitrogen (N) fertilizer applications are two of the most frequent agronomic practices applied to ensure rice yield, and they also profoundly affect the behavior of methanogens and methanotrophs. However, the effect of rice straw or its biochar combined with N fertilizer on the activities and compositions of methanogens and methanotrophs is still not well understood, especially in rice root zone soil in coastal saline paddy fields. Moreover, only few studies linking communities and functions of methanogens and methanotrophs are available, resulting in a lack of adequate indicators to predict methane production potential (MPP) or methane oxidation potential (MOP), for improving fertilizer strategies. Here, through quantitative PCR (qPCR), high-throughput sequencing, network analysis and linear regression model, we investigated the response of the abundances, compositions and activities of methanogens and methanotrophs to rice straw or its biochar combined with N fertilizer in rice root zone soil in coastal regions, and explored the relationships between MPP and methanogenic compositions as well as MOP between methanotrophic compositions, respectively. Therefore, a combination of pot and mesocosm experiment was conducted including seven fertilizer treatments: CK, without N fertilizer and rice straw return; SN100, 100 % N plus straw return; SN80, 80 % N plus straw return; SN60, 60 % N plus straw return; BN100, 100 % N plus rice biochar return; BN80, 80 % N plus biochar return; and BN60, 60 % N plus biochar return. Results showed that irrespective of MPP, MOP, or methanogenic and methanotrophic abundance, they all decreased significantly (P