Insights into the Driving Factors of Methane Emission from Double-Season Rice Field Under Different Fertilization Practices in South China
Paddy fields are the main agricultural source of greenhouse gas methane (CH<sub>4</sub>) emissions. To enhance rice yield, various fertilization practices have been employed in rice paddies. However, the key microbial and abiotic factors driving CH<sub>4</sub> emissions under...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-11-01
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| Series: | Agronomy |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4395/14/12/2767 |
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| Summary: | Paddy fields are the main agricultural source of greenhouse gas methane (CH<sub>4</sub>) emissions. To enhance rice yield, various fertilization practices have been employed in rice paddies. However, the key microbial and abiotic factors driving CH<sub>4</sub> emissions under different fertilization practices in paddy fields remain largely uncharted. This study conducted field experiments in a traditional double-cropping rice area in South China, utilizing five different fertilization practices to investigate the key factors influencing CH<sub>4</sub> emissions. High-throughput sequencing and PICRUSt2 functional prediction were employed to investigate the contributions of soil physicochemical properties, CH<sub>4</sub>-metabolizing microorganisms (methanogens and methanotrophs), and key genes (<i>mcrA</i> and <i>pmoA</i>) on CH<sub>4</sub> emissions. The results showed that CH<sub>4</sub> emission fluxes exhibited seasonal variations, with consistent patterns of change observed across all treatments for both early- and late-season rice. Compared to the no-fertilization (NF) treatment, cumulative CH<sub>4</sub> emissions were lower in early-season rice with green manure (GM) and straw returning (SR) treatments, as well as in late-season rice with GM treatment, while rice yields were maintained at higher levels. High-throughput sequencing analysis revealed that potential methanogens were primarily distributed among four orders: <i>Methanobacteriales</i>, <i>Methanocellales</i>, <i>Methanomicrobiales</i>, and <i>Methanosarcinales</i>. Furthermore, there was a significant positive correlation between the relative abundance of the CH<sub>4</sub>-related key gene <i>mcrA</i> and these microorganisms. Functional analysis indicated that these potential methanogens primarily produce methane through the acetoclastic and hydrogenotrophic pathways. Aerobic CH<sub>4</sub>-oxidizing bacteria, predominantly from the genus <i>Methylocystis</i>, were detected in all the treatments, while the CH<sub>4</sub> anaerobic-oxidizing archaea ANME-1b was only detected in chemical fertilization (CF) and cow manure (CM) treatments. Our random forest analysis revealed that the relative abundance of two methanogens (<i>Methanocellales</i> and <i>Methanosarcinales</i>) and two environmental factors (pH and DOC) had significant impacts on the cumulative CH<sub>4</sub> emissions. The variance decomposition analysis highlighted the CH<sub>4</sub>-metabolizing microorganisms explained 50% of the variance in the cumulative CH<sub>4</sub> emissions, suggesting that they are the key microbial factors driving CH<sub>4</sub> emissions. These findings provide guidance for the development of rational measures to reduce CH<sub>4</sub> emissions in paddy fields. |
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| ISSN: | 2073-4395 |