Statistical analysis of the major variables controlling methane emission from rice fields
TL;DR: In this paper, the authors developed a statistical model to relate CH4 flux in the rice-growing season to soil properties, water regime, water status in the previous season, organic amendment and climate.
Abstract: Rice cultivation is an important anthropogenic source of atmospheric methane (CH4), the emission of which is affected by management practices. Many field measurements have been conducted in major rice-producing countries in Asia. We compiled a database of CH4 emissions from rice fields in Asia from peer-reviewed journals. We developed a statistical model to relate CH4 flux in the rice-growing season to soil properties, water regime in the rice-growing season, water status in the previous season, organic amendment and climate. The statistical results showed that all these variables significantly affected CH4 flux, and explained 68% of the variability. Organic amendment and water regime in the rice-growing season were the top two controlling variables; climate was the least critical variable. The average CH4 fluxes from rice fields with single and multiple drainages were 60% and 52% of that from continuously flooded rice fields. The flux from fields that were flooded in the previous season was 2.8 times that from fields previously drained for a long season and 1.9 times that from fields previously drained for a short season. In contrast to the previously reported optimum soil pH of around neutrality, soils with pH of 5.0‐5.5 gave the maximum CH4 emission. The model results demonstrate that application of rice straw at 6tha � 1 before rice transplanting can increase CH4 emission by 2.1 times; when applied in the previous season, however, it increases CH4 emission by only 0.8 times. Default emission factors and scaling factors for different water regimes and organic amendments derived from this work can be used to develop national or regional emission inventories.
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TL;DR: The analysis indicates that investment in yield improvements compares favorably with other commonly proposed mitigation strategies, and should therefore be prominent among efforts to reduce future GHG emissions.
Abstract: As efforts to mitigate climate change increase, there is a need to identify cost-effective ways to avoid emissions of greenhouse gases (GHGs). Agriculture is rightly recognized as a source of considerable emissions, with concomitant opportunities for mitigation. Although future agricultural productivity is critical, as it will shape emissions from conversion of native landscapes to food and biofuel crops, investment in agricultural research is rarely mentioned as a mitigation strategy. Here we estimate the net effect on GHG emissions of historical agricultural intensification between 1961 and 2005. We find that while emissions from factors such as fertilizer production and application have increased, the net effect of higher yields has avoided emissions of up to 161 gigatons of carbon (GtC) (590 GtCO2e) since 1961. We estimate that each dollar invested in agricultural yields has resulted in 68 fewer kgC (249 kgCO2e) emissions relative to 1961 technology ($14.74/tC, or ∼$4/tCO2e), avoiding 3.6 GtC (13.1 GtCO2e) per year. Our analysis indicates that investment in yield improvements compares favorably with other commonly proposed mitigation strategies. Further yield improvements should therefore be prominent among efforts to reduce future GHG emissions.
938 citations
Cites methods from "Statistical analysis of the major v..."
...We follow the methodology outlined by Yan (14, 51) to calculate methane emissions from rice cultivation and GHGs from the burning of rice straw....
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...These values are derived following the methods and sources used by Yan et al. (14, 51–53)....
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...Yan X, Akiyama H, Yagi K, Akimoto H (2009) Global estimations of the inventory and mitigation potential of methane emissions from rice cultivation conducted using the 2006 Intergovernmental Panel on Climate Change guidelines....
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...Yan X, Yagi K, Akiyama H, Akimoto H (2005) Statistical analysis of the major variables controlling methane emission from rice fields....
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...Yan X, Ohara T, Akimoto H (2006) Bottom-up estimate of biomass burning in mainland China....
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TL;DR: In paddy soils, the management-induced, microbially mediated redox processes control the dynamics of soil minerals and soil organic matter, which are strongly related to the microbial accessibility of C and N, but also of Fe as discussed by the authors.
869 citations
TL;DR: In this article, a weighted meta-analysis was conducted based on data from 103 studies published up to April, 2013, to quantify the effect of biochar soil amendment (BSA) on crop productivity and to analyze the dependence of responses on experimental conditions.
Abstract: For the last decade, there has been an increasing global interest in using biochar to mitigate climate change by storing carbon in soil. However, there is a lack of detailed knowledge on the impact of biochar on the crop productivity in different agricultural systems. The objective of this study was to quantify the effect of biochar soil amendment (BSA) on crop productivity and to analyze the dependence of responses on experimental conditions. A weighted meta-analysis was conducted based on data from 103 studies published up to April, 2013. The effect of BSA on crop productivity was quantified by characterizing experimental conditions. In the published experiments, with biochar amendment rates generally <30 t ha−1, BSA increased crop productivity by 11.0 % on average, while the responses varied with experimental conditions. Greater responses were found in pot experiments than in field, in acid than in neutral soils, in sandy textured than in loam and silt soils. Crop response in field experiments was greater for dry land crops (10.6 % on average) than for paddy rice (5.6 % on average). This result, associated with the higher response in acid and sandy textured soils, suggests both a liming and an aggregating/moistening effect of BSA. The analysis suggests a promising role for BSA in improving crop productivity especially for dry land crops, and in acid, poor-structured soils though there was wide variation with soil, crop and biochar properties. Long-term field studies are needed to elucidate the persistence of BSA’s effect and the mechanisms for improving crop production in a wide range of agricultural conditions. At current prices and C-trading schemes, however, BSA would not be cost-effective unless persistent soil improvement and crop response can be demonstrated.
585 citations
Cites background from "Statistical analysis of the major v..."
...Moreover, such an incorporation of fresh organic matter would potentially lead to an increase in the production of methane (CH4) in rice paddies (Yan et al. 2005; Shang et al. 2011)....
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TL;DR: This chapter will describe the ecology of methanogens and methanotrophs and will give examples where production and emission of methane on the field scale can be understood on the basis of processes on the microscale.
Abstract: Rice agriculture feeds about a third of the world's population. However, rice fields are also an important source in the global budget of the greenhouse gas methane. The emission of methane from flooded rice fields is the result of the activity of methanogenic archaea that produce the methane and of methanotrophic bacteria that oxidize part of it, so that the ecology of these two physiological groups of microorganisms is key for the understanding of methane cycling in rice fields and for possible mitigation of emission from this important agro-ecosystem. In this chapter I will describe the ecology of methanogens and methanotrophs and will give examples where production and emission of methane on the field scale can be understood on the basis of processes on the microscale.
498 citations
TL;DR: In this paper, a long-term fertilizer experiment in Chinese double rice-cropping systems initiated in 1990 was used to gain an insight into a complete greenhouse gas accounting of GWP and GHGI.
Abstract: The impact of agricultural management on global warming potential (GWP) and greenhouse gas intensity (GHGI) is not well documented. A long-term fertilizer experiment in Chinese double rice-cropping systems initiated in 1990 was used in this study to gain an insight into a complete greenhouse gas accounting of GWP and GHGI. The six fertilizer treatments included inorganic fertilizer [nitrogen and phosphorus fertilizer (NP), nitrogen and potassium fertilizer (NK), and balanced inorganic fertilizer (NPK)], combined inorganic/organic fertilizers at full and reduced rate (FOM and ROM), and no fertilizer application as a control. Methane (CH4) and nitrous oxide (N2O) fluxes were measured using static chamber method from November 2006 through October 2009, and the net ecosystem carbon balance was estimated by the changes in topsoil (0–20 cm) organic carbon (SOC) density over the 10-year period 1999–2009. Long-term fertilizer application significantly increased grain yields, except for no difference between the NK and control plots. Annual topsoil SOC sequestration rate was estimated to be 0.96 t C ha−1 yr−1 for the control and 1.01–1.43 t C ha−1 yr−1 for the fertilizer plots. Long-term inorganic fertilizer application tended to increase CH4 emissions during the flooded rice season and significantly increased N2O emissions from drained soils during the nonrice season. Annual mean CH4 emissions ranged from 621 kg CH4 ha−1 for the control to 1175 kg CH4 ha−1 for the FOM plots, 63–83% of which derived from the late-rice season. Annual N2O emission averaged 1.15–4.11 kg N2O–N ha−1 in the double rice-cropping systems. Compared with the control, inorganic fertilizer application slightly increased the net annual GWPs, while they were remarkably increased by combined inorganic/organic fertilizer application. The GHGI was lowest for the NP and NPK plots and highest for the FOM and ROM plots. The results of this study suggest that agricultural economic viability and GHGs mitigation can be simultaneously achieved by balanced fertilizer application.
439 citations
Cites background or result from "Statistical analysis of the major v..."
...Rice plant serves as a main pathway of CH4 emission, and the dependence of CH4 emission on crop growth in rice paddies has been well documented (Huang et al., 2004a; Yan et al., 2005)....
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...Annual CH4 emissions in this study were comparable to those previous results in rice paddies under continuous waterlogging, but much higher than those from other studies in the single rice-cropping systems with midseason drainage (e.g. Cai et al., 1997; Yan et al., 2005; Zou et al., 2005; Khalil et al., 2008)....
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...The crop straw from the early rice were retained in the fields, providing a large addition of organic material under hot weather conditions favorable to quick decomposition during the late-rice cropping period (Huang et al., 2004a; Yan et al., 2005; Ma et al., 2009)....
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...…in this study were comparable to those previous results in rice paddies under continuous waterlogging, but much higher than those from other studies in the single rice-cropping systems with midseason drainage (e.g. Cai et al., 1997; Yan et al., 2005; Zou et al., 2005; Khalil et al., 2008)....
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...The crop straw from the early rice were retained in the fields, providing a large addition of organic material under hot weather conditions favor- able to quick decomposition during the late-rice cropping period (Huang et al., 2004a; Yan et al., 2005; Ma et al., 2009)....
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References
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TL;DR: In this paper, the chemistry of submerged soils is discussed and the role of lake, estuarine, and ocean sediments as reservoirs of nutrients for aquatic plants and as sinks for terrestrial wastes.
Abstract: Publisher Summary This chapter discusses the chemistry of submerged soils. The chemical changes in the submerged materials influence: (a) the character of the sediment or soil that forms, (b) the suitability of wet soils for crops, (c) the distribution of plant species around lakes and streams and in estuaries, deltas, and marine flood plains, (d) the quality and quantity of aquatic life, and (e) the capacity of lakes and seas to serve as sinks for terrestrial wastes. The single electrochemical property that serves to distinguish a submerged soil from a well-drained soil is its redox potential. The redox potential of a soil or sediment provides a quick, useful, semiquantitative measure of its oxidation–reduction status. Two recent developments have stimulated interest in the chemistry of submerged soils: the breeding of lowland rice varieties, with a high yield potential, and the pollution of streams, lakes, and seas, by domestic, agricultural, and industrial wastes. The chemistry of submerged soils is valuable: (a) in understanding the soil problems, limiting the performance of high-yielding rice varieties, and (b) in assessing the role of lake, estuarine, and ocean sediments as reservoirs of nutrients for aquatic plants and as sinks for terrestrial wastes.
2,651 citations
"Statistical analysis of the major v..." refers background in this paper
...Furthermore, soil pH stabilizes at around neutrality after flooding (Ponnamperuma, 1972)....
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TL;DR: In this article, the anaerobic zones of submerged soils by methanogens and methanotrophs are oxidised into CO2 in the aerobic zones of wetland soils and in upland soils.
1,743 citations
"Statistical analysis of the major v..." refers background in this paper
...In contrast, in the field, methanogens can adapt to an acidic environment (see Le Mer & Roger, 2001)....
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01 Jan 2000
TL;DR: In this article, the authors present a good practice guideline for the estimation of methane emissions from solid waste disposal for national greenhouse gas inventories, and discuss the emission estimation methods given in the IPCC 1996 Revised Guidelines.
Abstract: The purpose of this paper is to support the development of so-called good practice guidelines for the estimation of methane (CH 4) emissions from solid waste (SW) disposal for national greenhouse gas inventories. The paper reviews and discusses the emission estimation methods given in the IPCC 1996 Revised Guidelines (IPCC Guidelines), and uncertainty and quality management issues related to the emission estimation. At solid waste disposal sites (SWDS) the degradable organic carbon in waste is decomposed by bacteria under anaerobic conditions into methane (CH 4) and other compounds. The CH 4 emissions from SWDS are important contributors of global anthropogenic CH 4 emissions. The IPCC Guidelines give two methods for estimation CH 4 emissions from solid waste disposal. The IPCC default method is a simple mass balance calculation which estimates the amount of CH 4 emitted from the SWDS assuming that all CH 4 is released the same year the waste is disposed of. The other method outlined in the IPCC Guidelines is the so-called First Order Decay (FOD) method. The FOD method takes the time factors of the degradation process into account, and produces annual emission estimates that reflect this process, which can take years, even decades. The estimates on annual emissions produced by the two methods are therefore not comparable. The FOD method produces better estimates on annual emissions, whereas the IPCC default method has merits e.g. in studies comparing the potential to reduce the CH 4 emissions by alternative waste treatment methods. The use of the IPCC default method and FOD method require as input annual SW disposal data including information on the composition of the waste and on the conditions at the SWDS. The IPCC default method requires this data only for the inventory years, whereas the FOD method requires data for also the past 20-25 or more years. In addition, the rate of degradation for waste disposed at SWDS needs to be determined in the FOD method. The IPCC Guidelines contain default values for most of the data needed in the use of the default method, whereas the guidance and default values needed in the use of the FOD method are insufficient. The uncertainties in the emission estimates produced by both the IPCC method and the FOD method are large in most countries. Even few industrialised countries have good SW disposal data based on weighing of amounts disposed and frequent sampling to determine the composition …
914 citations
Book•
01 Jan 1986
TL;DR: In this article, the authors present a conceptual diagram as a modelling tool for ecological models and apply it to the problem of environmental management in the field of biogeochemical models, where the conceptual diagram is used to model growth and population dynamics.
Abstract: 1. Introduction. Physical and mathematical models. Models as a management tool. Models as a scientific tool. 2. Concepts of Modelling. Elements of modelling. Modelling procedure. Classes of ecological models. Selection of model complexity and structure. Verification. Sensitivity analysis. Parameter estimation. Validation. Constraints on models. Computers and ecological modelling. 3. Ecological Modelling. Application of unit processes in ecological modelling. Physical processes. Chemical processes. Photosynthesis. 4. Conceptual Models. Application of conceptual models. Types of conceptual diagrams. The conceptual diagram as a modelling tool. 5. Static Models. Application of static models. Input/output environ analysis. Response models. 6. Modelling Population Dynamics. Basic concepts. Growth models. Interactions between population. Matrix models. Harvest models. 7. Dynamic Biogeochemical Models. Application of dynamic models. BOD/DO models. Application of hydrodynamics in biogeochemical models. Eutrophication models. Wetland models. Models in ecotoxicology. Models in toxicology. Distribution of air pollutants. Models of soil processes, plant growth and crop production. 8. Application of Ecological Models in Environmental Management. Environmental management models. Environmental problems and models. Management examples. 9. Ecosystems Characteristics and Models. Characteristic features of ecosystems. Ecosystem dynamics. Ecological models with goal functions. Application of catastrophe theory to ecological modelling. References. Index.
862 citations
TL;DR: Methanogens are strict anaerobes which share a complex biochemistry for methane synthesis as part of their energy metabolism as mentioned in this paper and have been studied extensively in the literature.
700 citations