Methane Emission In Paddy Field Research Articles

Enhancing bioelectricity generation and mitigating methane emissions in paddy fields: A novel approach using activated biochar in plant microbial fuel cells

In the innovative realm of green energy solutions, plant microbial fuel cells (PMFCs) have emerged as a promising frontier, embodying a greener technological approach. However, PMFC is not yet viable for large-scale application due to its low voltage generation. This study explores the integration of PMFC technology in paddy field, using activated biochar as electrode material to enhance voltage production while reducing methane emission. According to the findings, rice PMFCs equipped with activated biochar achieved the highest power density, reaching an impressive 106.67 mW m−2 of anode area, significantly outperforming SMFCs, which peaked at 38.28 mW m−2 when integrated with a biochar anode. Additionally, rice-PMFCs emitted 38 % less methane than the normal rice plant, while the reduction was 27.1 % for rice plants equipped with activated biochar, with no significant change in plant yield observed. Furthermore, PMFCs reduced greenhouse gas emissions by 70 % and 67 % compared to traditional coal and natural gas-based power plants, respectively. In summary, activated biochar shows promise as a potent alternative to traditional graphite electrodes in PMFCs.

Fe(III) stabilizing soil organic matter and reducing methane emissions in paddy fields under varying flooding conditions

The role of iron (Fe) in soil organic matter (SOM) stabilization and decomposition in paddy soils has recently gained attention, but the underlying mechanisms during flooding and drying periods remain elusive. As the depth water layer is maintained in the fallow season, there will be more soluble Fe than during the wet and drainage seasons and the availability of oxygen (O2) will be different. To assess the influence of soluble Fe on SOM mineralization during flooding, an incubation experiment was designed under oxic and anoxic flooding conditions, with and without Fe(III) addition. The results showed that Fe(III) addition significantly (p < 0.05) decreased SOM mineralization by 14.4 % under oxic flooding conditions over 16 days. Under anoxic flooding incubation, Fe(III) addition significantly (p < 0.05) decreased 10.8 % SOM decomposition, mainly by 43.6 % methane (CH4) emission, while no difference in carbon dioxide (CO2) emission was noticed. These findings suggest that implementing appropriate water management strategies in paddy soils, considering the roles of Fe under both oxic and anoxic flooding conditions, can contribute to SOM preservation and mitigation of CH4 emissions.

The potential of vegetation indices: estimating methane emissions in paddy fields under nighttime warming and water saving conditions

AbstractNondestructive and rapid methods for estimating methane emissions from paddy fields are helpful in indentifying options for emission mitigation, both at global and local scales. However, few studies have used an approach of vegetation indices for estimating methane emissions in paddy fields from ground‐based hyperspectral data. Therefore, this study systematically analyzed the quantitative relationship of methane emissions from rice fields to hyperspectral vegetation indices based on hyperspectral reflectance data of rice canopy. A field experiment was designed with two nighttime warming levels, that is, nighttime warming and control (ambient temperature), and two irrigation levels, that is, flooding (control, with 5 cm depth of water layer) and wetting (water saving irrigation, without water layer). Results showed that the newly developed three‐band index (R1139 − R960)/(R1139 + R960 − 2R944) (Rλ is the reflectance value at wavelength λ) was recommended as the optimal index for monitoring methane emission from paddy field, generated coefficients of determination, root mean square error, and residual prediction deviation values between the measured and predicted values of 0.687, 1.424 mg m−2 h−1, and 1.83, respectively. This study provides a theoretical basis and technical support for methane emissions assessment in paddy fields based on vegetation indices. © 2020 Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

The pH-based ecological coherence of active canonical methanotrophs in paddy soils

Abstract. Soil pH is considered one of the main determinants of the assembly of globally distributed microorganisms that catalyze the biogeochemical cycles of carbon (C) and nitrogen (N). However, direct evidence for niche specialization of microorganisms in association with soil pH is still lacking. Using methane-oxidizing bacteria (methanotrophs) as a model system of C cycling, we show that pH is potentially the key driving force selecting for canonical γ (type I) and α (type II) methanotrophs in rice paddy soils. DNA-based stable isotope probing (DNA-SIP) was combined with high-throughput sequencing to reveal the taxonomic identities of active methanotrophs in physiochemically contrasting soils from six different paddy fields across China. Following microcosm incubation amended with 13CH4, methane was primarily consumed by Methylocystis-affiliated type II methanotrophs in soils with a relatively low pH (5.44–6.10), whereas Methylobacter- or Methylosarcina-affiliated type I methanotrophs dominated methane consumption in soils with a high pH (7.02–8.02). Consumption of 13CH4 contributed 0.203 % to 1.25 % of soil organic C, but no significant difference was observed between high-pH and low-pH soils. The fertilization of ammonium nitrate resulted in no significant changes in the compositions of 13C-labeled methanotrophs in the soils, although significant inhibition of methane oxidation activity was consistently observed in low-pH soils. Mantel analysis further validated that soil pH, rather than other parameters tested, had significant correlation to the variation in active methanotrophic compositions across different rice paddy soils. These results suggest that soil pH might have played a pivotal role in mediating the niche differentiation of ecologically important aerobic methanotrophs in terrestrial ecosystems and imply the importance of such niche specialization in regulating methane emissions in paddy fields following increasingly intensified input of anthropogenic N fertilizers.

Rice root morphological and physiological traits interaction with rhizosphere soil and its effect on methane emissions in paddy fields

Rice (Oryza sativa L.) paddies contribute approximately 7–17% to total global methane (CH4) emissions and are considered an important source of human-induced climate change. However, the interactive effects of rice roots and soil microbes on CH4 emissions in paddy fields are not clearly understood. We conducted two field experiments over three years. Soil CH4 fluxes and cumulative CH4 emissions, rice root traits, and microbial communities and activities in soil were measured using three mid-season japonica rice cultivars (Wuyujing 3, Zhendao 88, and Huaidao 5) that have the same growth durations and similar aboveground traits before heading. The CH4 emissions during the mid-growing period (from panicle initiation to heading) contributed 39.0–49.7% of the total emissions during the entire growing season and differed significantly among the rice cultivars. The root morphological and physiological traits (i.e. root dry weight, root length, root oxidation activity, and root radial oxygen loss) were negatively correlated with CH4 fluxes. Compared to the zero-N control, application rates of N fertilizer at 54 and 108 kg ha−1 increased root biomass of cultivar Zhendao 88 by 10.1% and 17.3%, respectively, leading to corresponding decreases in CH4 emissions by 12.7% and 22.9%. The root exudates (malic acid, succinic acid, and citric acid) promoted the abundance and activity of methanotrophs, which was the primary factors underlying the low CH4 emissions in the paddy fields. Our findings suggested that stronger root systems, higher oxygen delivered by roots available for methanotrophs and suitable root exudates interacted in the rhizosphere, established a favourable habitat for microbial populations, and reduced CH4 emissions in paddy fields.

Methane Emission in Paddy Field with Local Rice Variety in Peat- Swamps Agricultural Lands, South Kalimantan

Methane Emission in Paddy Field with Local Rice Variety in Peat- Swamps Agricultural Lands, South Kalimantan

Alternate wetting and moderate drying increases rice yield and reduces methane emission in paddy field with wheat straw residue incorporation

AbstractWheat residue incorporation into the rice paddy field is becoming a popular practice in rice production in China's main rice‐growing area but risks an increased emission of greenhouse gases. This study investigated if an alternate wetting and moderate drying (AWMD) irrigation regime in rice production reduces CH4 emission and increases grain yield when wheat straw residues are incorporated into rice paddy field. One super rice variety was field‐grown in 2012 and 2013 and subjected to four irrigation and straw incorporation treatments: continuously flooded (CF) without straw incorporation (−S), AWMD without straw incorporation (AWMD−S), then CF with straw incorporation (CF + S) and AWMD + S. When compared with the CF, the AWMD regime increased grain yield and water use efficiency (WUE, grain yield over the amount of water used) by 2.7% and 27.6%, respectively, under −S, and by 18.0 and 50.0%, respectively under +S. The AWMD + S treatment also significantly increased nitrogen use efficiency (NUE) compared with the CF + S treatment. The increase in grain yield, WUE and NUE in the AWMD regime, especially under +S, were attributed mainly to a greater root oxidation activity, deeper root distribution and increases in productive tillers, crop growth rate and nonstructural carbohydrate remobilization during grain filling. There was a total of 0.49 kg N2O‐N ha−1 more loss in the AWMD than in the CF regime. However, the AWMD regime substantially decreased seasonal CH4 emissions, global warming potential (GWP, including both CH4 and N2O) and greenhouse gas intensity (grain yield over GWP) by 49.8%, 45.2% and 46.7%, respectively, under −S, and by 57.5, 55.9% and 62.6%, respectively, under +S, when compared with the CF regime. The results demonstrate that the AWMD is an effective practice to increase grain yield and resource‐use efficiency and reduce environmental risks especially, when wheat straw is incorporated into paddy field.

Complete Genome Sequence of a Thermophilic Methanogen, Methanocella conradii HZ254, Isolated from Chinese Rice Field Soil

Members of the order Methanocellales play a key role in methane emissions in paddy fields. Because of their slow growth and fastidious culture conditions, pure cultures are difficult to isolate and have been unavailable until recently. Here we report the complete genome sequence of a novel isolate in this group, Methanocella conradii strain HZ254.