Methane production, oxidation and mitigation: A mechanistic understanding and comprehensive evaluation of influencing factors (original) (raw)
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Methane emission from rice ecosystems: 100 years of research. A review
Rice soils produce methane, a potent greenhouse gas that is closely associated with global warming impacts. Ten decades of research on methane emission from rice fields has significantly contributed towards better understanding of this complex ecosystem. Despite its complexity, the overall mechanisms involved in methane dynamics in rice fields have clearly demonstrated that methane production is as a consequence of anaerobic degradation of organic matter coupled with the activities of methanogens and more than 90 % of the emission facilitated by rice plants which acts as a chimney to transport this gas to the atmosphere. Further, the activities of methanotrophs and sulphate reducing bacteria may play a pivotal role in methane dynamics in rice ecosystem. This review figured out key factors that control methane production, oxidation and transport. As an outcome of this research, we have ascertained the fact that in order to circumvent the methane emission, water management, balanced fertilization encompassing proper choice of fertilizers, less emitting rice genotypes,rhizoengineering to promote methanotrophs population besides system of rice intensification are some of the vital mitigation strategies.
Methane (CH4) is a potent green house gas and second in importance after carbon dioxide (CO2) with a global warming potential of 25 times more than CO2. Paddy fields are important sources of methane and contribute in approximately 15–20% of the annual global methane efflux. Cultivation systems can affect the methane emission by their different water management and practices. One of the cultivation methods is the system of rice intensification (SRI). Considering the water management system and the plant density, in this method less methane is expected compared to conventional cultivation method. Consequently, current study has been done to evaluate the influence of two SRI methods on methane emission. For this purpose, closed chamber applied to measure methane emission. As a result, conventional method showed the highest total methane flux compared to original SRI treatments and triangular pattern. The pattern of water management was the most influencing factor lead to lower methane ...
Review Article: Improving Strategies for Methane Mitigation from Rice Soil
Methane is a potent greenhouse gas after carbon dioxide with global warming potential (GWP) of 72 over a 20-year period. Paddy fields are indicated as a considerable source of anthropogenic methane emissions, and account for up to 12% of these emissions. Rice is the main food for one-third of the global population; and, the demand for this crop increases continuously because of the increasing trend in the world population growth. Therefore, the cultivation area of rice is growing. In this situation, applying methane mitigation approaches are necessary. Evaluating influencing factors leads us to detect possible ways for methane mitigation. This paper will review the effect of rice cultivar, water management, and fertilizers on methane emissions from rice fields. Moreover, microbial communities responsible for production and oxidation of methane in rice fields will be reviewed. In this review, we tried to include methane mitigation opportunities.
Effect of cultivation system on the methane emission from rice soil
2012
Methane (CH4) is a potent green house gas and second in importance after carbon dioxide (CO2) with a global warming potential of 25 times more than CO2. Paddy fields are important sources of methane and contribute in approximately 15-20% of the annual global methane efflux. Cultivation systems can affect the methane emission by their different water management and practices. One of the cultivation methods is the system of rice intensification (SRI). Considering the water management system and the plant density, in this method less methane is expected compared to conventional cultivation method. Consequently, current study has been done to evaluate the influence of two SRI methods on methane emission. For this purpose, closed chamber applied to measure methane emission. As a result, conventional method showed the highest total methane flux with emitting of 26.4 g CH4 m -2 compared to original SRI treatments and triangular pattern (7.7 g CH4 m -2 and 8.9 g CH4 m -2 ). The pattern of water management was the most influencing factor lead to lower methane emission in SRI treatments. In addition, SRI treatments produced higher yield than the conventional method. This could be a promising result toward a sustainable rice production.
Factors affecting methane emission from rice fields
Atmospheric Environment, 1996
Emission of CH4 from ricefields is the result of anoxic bacterial methane production. Global estimates of annual CH4 emission from ricefields is 100 Tg. CH4 emission data from limited sites are tentative. It is essential that uncertainty in individual sources is reduced in order to develop feasible and effective mitigation options which do not negate gains in rice production and productivity. Field studies at the International Rice Research Institute show that soil and added organic matter are the sources for initial methane production. Addition of rice straw enhances methane production. Roots and root exudates of wetland rice phmts appear to be the major carbon sources at ripening stage. The production and transport of CH4 to the atmosphere depend on properties of the rice plant. Under the same spacing and fertilization, the traditional variety Dular emitted more CH4 per day than did the new plant type IR65597. Upon flooding for land preparation anaerobic conditions result in significant amount of methane being formed. Drying the field at midtillering significantly reduced total CH4 emissions. Large amounts of entrapped CH4 escape to the atmosphere when floodwater recedes upon drying at harvest. Cultural practices may account for 20% of the overall seasonal CH4 emissions.
Evaluation of methane oxidation in rice plant-soil system
2002
Mechanisms of methane oxidation in the plant-soil system of rice were studied in a pot experiment using two cultivars (PSBRc-30 and IR72) at two growth stages (flowering and heading). Methane emission was measured by chambers, while methane oxidation was determined through propylene amendment as an alternative substrate to be propylene oxide (PPO) and acetylene as an inhibitor for methane oxidizing (methanotrophic) bacteria. Cell numbers (methanotrophic and methanogenic bacteria) were determined by the most probable number method. The cultivar PSBRc-30 consistently showed higher methane emission rates than IR72. Methane flux clearly decreased from flowering to heading stages in both cultivars. This observation was largely reflected by trends in the mechanisms involved: either methanogenic cell numbers or activities decreased with plant age while methanotrophic cell numbers or activities generally showed an increasing trend. The methanogenic population was in the order of 10 5 g −1 dry soil, while the population of methanotrophs ranged from 10 4 to nearly 10 6 g −1 dry soil. Methanotrophic activity followed the order; root (1.7-2.8 nL PPO g −1 DM h −1) > shoot (0.7-2.0) > soil (0-0.4) when the consumption of alternative substrate was related to dry matter. Derived from the estimated amounts of soil and plant biomass in the pot experiment, however, the soil generally accounted for more than 90% of the total methane oxidation. Within the plant segments, methane oxidation activities in the root exceeded those of the shoot by factor of approximately 10.
Methane in rice agriculture: A review
Journal of scientific and industrial research
This review gives an account of mechanisms of methane production and emission from flooded paddy fields. Future methane emission scenarios show that methane emissions in 2030 in India are projected to reach 24.4 Tg (reference scenario), 21.3 Tg (medium mitigation scenario) and 17.6 Tg (strong mitigation scenario). Morpho-physiological parameters (leaf number, tiller number and plant biomass) are reported to influence methane emissions. Use of nitrification inhibitors (prilled urea and nimin) are reported to be suitable methane mitigation options.
Methane production, oxidation, and emission from Indian rice soils
Methane Emissions from Major Rice Ecosystems in Asia, 2000
Experiments were conducted to investigate methane (CH 4 ) production, oxidation, and emission from flooded rice soils. Incorporation of green manure (Sesbania rostrata) into rice fields led to a several-fold increase in CH 4 emission. A stimulatory effect of organic sources on CH 4 production in soil samples was noticed even under nonflooded conditions. Addition of rice straw at 1% (w/w) to nonflooded soil samples held at -1.5 MPa effected a 230-fold increase in CH 4 production over that in corresponding unamended soil samples at 35 d, as compared with a threefold increase in rice straw-amended soil over that in unamended soil under flooded conditions. In a study involving two experimental field sites differing in water regimes but planted to the same rice cultivar (cv Gayatri) and fertilized with prilled urea at 60 kg N ha -1 , the field plots with deep submergence of around 30 cm (site I) emitted distinctly more CH 4 than did the plots with continuous water depth of 3-6 cm (site II). Likewise, in another incubation study, CH 4 production in flooded soil samples increased with a progressive increase in standing water column from 5 mm to 20 mm. Application of carbamate insecticide, carbofuran, at 2 kg ai ha -1 to rice fields retarded CH 4 emission through enhanced CH 4 oxidation. Hexachlorocyclohexane was found to inhibit CH 4 emission. The results suggest the need for extensive research efforts to develop technologies with dual objectives of environmental protection and crop productivity.