Search

Mitigating the atmospheric greenhouse effect while enhancing the inherent soil quality and productive capacity is possible through soil carbon (C) sequestration, which has a significant potential to counteract the adverse effects of agroecosystem level C emission through natural and anthropogenic means. Although rice is the most important food in India, feeding more than 60% of the country's population, it is commonly blamed for significant methane (CH4) emissions that accelerate climate change. Higher initial soil organic matter concentrations would create more CH4 under the flooded soil conditions, as reducible soil C is a prerequisite for CH4 generation. In India, rice is generally cultivated in lowlands under continuous flooding. Less extensive organic matter breakdown in lowland rice agroecosystems often significantly impacts the dynamics of soil active and passive C pools. Change from conventional to conservation agriculture might trap a significant quantity of SOC. The study aims to investigate the potential of rice-based soils to sequester C and reduce the accelerated greenhouse effects through modified farming practices, such as crop residue retention, crop rotation, organic farming, varietal selection, conservation agriculture, integrated nutrient management, and water management. Overall, lowland rice agroecosystems can sequester significant amounts of SOC, but this potential must be balanced against the potential for CH4 emissions. Management practices that reduce CH4 emissions while increasing soil C sequestration should be promoted and adopted to maximize the sustainability of rice agroecosystems. This review is important for understanding the effectiveness of the balance between SOC sequestration and CH4 emissions in lowland rice agroecosystems for adopting sustainable agricultural practices in the context of climate change. [ABSTRACT FROM AUTHOR]

Agricultural soil acts as a source and sink of important greenhouse gases (GHGs) like methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2). Rice paddies have been a major concern to scientific community, because they produce the threatening and long-lasting GHGs mainly CH4 and N2O. Around 30% and 11% of global agricultural CH4 and N2O, respectively, emitted from rice fields. Thus, it is urgent to concurrently quantify the fluxes of CH4 and N2O to improve understanding of both the gases from rice fields and to develop mitigation strategies for upcoming climate change reduction. An effort is being made in this review to discuss exclusively the emission of CH4 and N2O under normal and controlled conditions in different locations of India and also addresses the current synthesis of available data on how field and crop management activities influence CH4 and N2O emissions in rice fields. Making changes to conventional crop management regimes could have a significant impact on reducing GHG emissions from rice field. Environmental and agricultural factors related to soil could be easily altered by management practices. So, knowing the mechanism of CH4 and N2O production and release in the rice field and factors controlling the emissions is fundamental to develop well-organized strategies to reduce emissions from rice cultivated soil. This will help the regulatory bodies or policy makers to formulate adequate policies for agricultural farmers to refine the GHG emissions as well as minimize the global climate change. [ABSTRACT FROM AUTHOR]

Aquaculture practices are steadily increasing to meet the fish demand, especially in tropical countries like India. However, efforts to characterize the contribution of these aquaculture ponds towards greenhouse gas emission like CH4 are still very few. CH4 concentration in water [pCH4(water)] and air–water CH4 fluxes were estimated (during the summer months) in two sewage-fed ponds having different depths situated in the East Kolkata Wetlands, India (a Ramsar site). pCH4(water) in both of these ponds showed significant positive correlation with water temperature (R2 = 0.68 and 0.71, p < 0.05). Daily mean chlorophyll-a, turbidity, biochemical oxygen demand (BOD) and gross primary productivity (GPP) also showed positive correlation with pCH4(water). This indicated that higher primary production and presence of turbid materials acted as substrates for methanogenesis, which favoured air–water CH4 effluxes towards atmosphere. Mean air–water CH4 fluxes in the ponds having depth of 1.1 m and 0.6 m were observed to be 24.79 ± 12.02 mg m−2 h−1 and 6.05 ± 3.14 mg m−2 h−1 respectively. Higher depth facilitated net heterotrophic conditions, which led to lower dissolved oxygen levels, which, in turn, led to lower rate of CH4 oxidation. Moreover, under reduced photosynthetically active radiation (in the pond having greater depth), the pH values were comparatively lower (~7.7), which further facilitated a favourable condition for the methanogens to grow. On the whole, it was inferred that apart from pre-established physicochemical factors, depth was also found to play a decisive role in regulating the air–water CH4 fluxes from these aquaculture ponds. In future, continuous sampling should be carried out (by chamber method) to take into account the ebullition CH4 fluxes, and more number of ponds should be sampled throughout a complete annual cycle to have a more holistic understanding about this cluster of sewage-fed aquaculture ponds. [ABSTRACT FROM AUTHOR]

The present study was undertaken to quantify methane emission from livestock production system in India. The computational results showed that the total methane emission from the livestock production system at 2012 population base was 12.28 million tonne. In the total methane emission from enteric fermentation, share of cattle is marginally lower (60%) than its share in the bovine population (64%) while the share of buffalo (40%) is marginally higher than its share in the population (36%). Cattle adult male account for more than 35% of the emission while buffalo in-milk accounts for little more than 46.7% of the emission. Methane emission from manure management for 2012 livestock population was estimated to be 0.20 million tonne. Other livestock like goat, sheep, camel and horses emit around 7.5% of total methane emission from both the sources. The estimates of methane emission from Indian livestock will help the policy makers and environmentalist of the country in designing mitigation strategies. [ABSTRACT FROM AUTHOR]

Major green house gases are carbon dioxide, methane, and nitrous oxide which are emitted directly and indirectly by ruminants. More than 80 per cent methane is normally produced during enteric fermentation. Methane has the second largest contributor to the green house effect and has 23 times more global warming potential than carbon dioxide. The Indian contribution of methane from all sources is around 12 per cent of total world production, in which mostly by emission by ruminants. India possesses largest ruminant population. An effort is made to mitigate the methane production in the ruminants. Nutritional management like good quality feed, use of higher concentrates, supplementing cattle diets with urea molasses block licks, fiber palletisation, breeding management like AI., ETT, In vitro fertilization which improves genetics and reproductive efficiency can also improve production efficiency which reduces green house gas emission. [ABSTRACT FROM AUTHOR]

We have studied the seasonal and tidal variation of methane (CH 4 ) and nitrous oxide (N 2 O) emission from the intertidal sediment of Bhitarkanika mangrove in the east coast of India. Seasonal variability study was conducted at five sites (three replicate of each site) inside the core area of the national park during three different seasons (summer, monsoon and winter) whereas tidal variation was studied at three different sites outside the core area during monsoon and winter season. Both CH 4 and N 2 O emission from the intertidal sediment were significantly higher under the low tide condition during the winter season. During the study period CH 4 emission from five different sites was ranged between 0.08 and 2.30 mg m −2 h −1 and the N 2 O emission was ranged between 9.0 and 187.58 μg m −2 h −1 . Average seasonal N 2 O emission (μg m −2 h −1 ) from five different sites followed the order: winter (115.60 ± 21.90) > summer (45.29 ± 7.78) > monsoon (16.98 ± 2.54). CH 4 and N 2 O emission was also recorded significantly higher during the winter season over the tidal cycle of three sampling locations. The CH 4 emission was negatively correlated with sediment salinity (r = −0.91, P < 0.05) and SO 4 –2 (r = −0.89, P < 0.05) concentration whereas; the N 2 O emission was positively correlated with sediment salinity (r = 0.48) and NO 3 − –N (r = 0.88, P < 0.05) concentration during the monsoon season. Positive correlation of N 2 O emission with the sediment NO 3 − –N indicates possible influence of upstream anthropogenic activities on N 2 O emission from the mangrove sediment. In general, methylamine utilizing methanogen and denitrifying bacterial population was significantly higher during winter season in the mangrove sediment. The study concludes that the CH 4 and N 2 O emission from the sediment at different sites during different seasons are influenced by allochthonous carbon and nitrogenous materials. [ABSTRACT FROM AUTHOR]

Methane release events have been linked to global warming, alteration of the carbon cycle and influence on biota. However, unequivocal evidence of paleomethane release events are limited. We report several negative carbon stable isotope excursions in planktic and benthic foraminifera in a core (MD161-8) from the Krishna-Godavari (K-G) Basin, Bay of Bengal. The most negative δ13C spikes are recorded during the marine isotope stages MIS-4 and at the transition of MIS-5 to 4. Occurrence of highly 13C depleted (average δ13C = −48 ± 2.4‰ VPDB) authigenic high magnesian calcite are also reported within this time window from the core MD161-8. In the present work an unequivocal explanation for the observed 13C depletion in the marine planktic and benthic foraminifera is difficult to achieve solely from the optical/electron microscopy or C-O stable isotope ratio analyses due to possible influence of diagenetic alteration. We attribute the observed episodic methane expulsion events, as inferred from the negative δ13C excursions and earlier reports on the occurrence chemosynthetic bivalves and Mo concentration anomaly to the destabilization of the base of gas hydrate stability zone (BGHSZ). Sea level drop and shale tectonics induced focused fluid flow are the two possible causes of hydrate destabilization discussed here. Shale tectonics were possibly responsible for creating fault systems which acted as the conduit for gas flow through the sediment column and subsequent seepage. Shale and salt tectonics in the passive continental margins being a globally observed phenomenon, its role as an important driving force for enhanced methane emission needs detailed investigation to understand the climatic perturbations through geologic time. Additional evidence of methane emission from site MD161-15 further supports the link between shale tectonics and methane emission. [ABSTRACT FROM AUTHOR]

Abstract: In the tropical experimental rice field of Central Rice Research Institute, Odisha, India, an experiment was conducted during the dry season (January–April) and wet season (July–November) of rice cultivation to study the effect of nitrogen (N), phosphorus (P) and potassium (K) fertilizer application on grain yield and methane (CH4) emission. The experiment was carried out with five treatments (No fertilizer (control), N-fertilizer, P-fertilizer, K-fertilizer and N + P + K fertilizer) with three replicates of each under a completely randomized block design. Significantly higher CH4 emission was recorded from all plots during wet season. Among fertilizer applied plots, significantly higher CH4 emission was recorded from N-fertilizer applied plots (dry season: 80.27 kg ha−1; wet season: 451.27 kg ha−1), while significantly lower CH4 emission was recorded from N + P + K applied plots (dry season: 34.60 kg ha−1; wet season: 233.66 kg ha−1). Low cumulative CH4 emission to grain yield ratio was recorded from N + P + K applied plots during both seasons (83.57 kg Mg−1 grain yield during dry season and 77.14 kg Mg−1 grain yield during wet season). CH4 emission from different treatment was positively correlated with microbial biomass carbon (r = 0.516), readily mineralizable carbon (r = 0.621) and sugar (r = 0.340) content of the soil. Negative CH4 emission was recorded during the fallow period which may be attributed to higher methanotrophic bacterial population. Study suggests that the effects of P and K-fertilizer on CH4 emission from rice field along with the CH4 emission during the fallow period need to be considered to reduce the uncertainty in upscaling process. [Copyright &y& Elsevier]

Abstract: In this article, system dynamics modeling approach has been used to quantify the methane emission from municipal solid waste (MSW) disposal in Delhi. The contribution of MSW management measures to mitigate methane emission proposed in MSW management scheme has been investigated using various possible scenarios analysis. If the current waste management policies are followed, the methane emission is projected to reach 254Gg/year by the year 2025. The results indicate that the proposed waste management policy for Delhi would significantly reduce the methane emission to the level of 2001 by the year 2025 despite an almost two-fold increase in waste generation. Energy recovery form various treatment and disposal methods can also contribute indirectly to the reduction of greenhouse effect by replacing fossil fuels in electricity production. [Copyright &y& Elsevier]

Sedimentary methane (CH4) fluxes and oxidation rates were determined over the wet and dry seasons (four measurement campaigns) in Pulicat lake, an extensive shallow estuary in south India. Dissolved CH4 concentrations were measured at 52 locations in December 2000. The annual mean net CH4 flux from Pulicat lake sediments was 3.7 x 109 g yr-1 based on static chamber measurements. A further 1.7 x 109 g yr-1 was estimated to be oxidized at the sediment-water interface. The mean dissolved concentration of CH4 was 242 nmol l-1 (ranging between 94 and 501 nmol l-1) and the spatial distribution could be explained by tidal dynamics and freshwater input. Sea-air exchange estimates using models, account only for ∼13% (0.5 x 109 g yr-1) of the total CH4 produced in sediments, whereas ebullition appeared to be the major route for loss to the atmosphere (∼63% of the net sediment flux). We estimated the total atmospheric source of CH4 from Pulicat lake to be 0.5 to 4.0 x 109 g yr-1. [ABSTRACT FROM AUTHOR]

Abstract: Flooded paddy is considered to be one of the major anthropogenic sources of atmospheric methane (CH4), a potent greenhouse gas. Emission of CH4 from flooded rice soils is affected by a multitude of factors including crop management practices. In a field study, CH4 fluxes from a sub-humid tropical flooded field of Cuttack, eastern India, as affected by planting with 20 and 35-day old rice (Oryza sativa L.) seedlings on two sets of planting dates were measured with the closed chamber method in 2002–2003 encompassing wet (kharif) season, 2002 and dry (rabi) season, 2003. In the wet season of 2002, CH4 emission from staggered planting was measured with two varieties viz. Lalat and Gayatri, while during the dry season of 2003, the experiment was conducted with cv. Lalat. CH4 emission was low from plots planted to aged seedlings (35-day) as well as seedlings transplanted late in both sets of experiments that were transplanted to the main field with an interval of 15 days during the two growing seasons. Cumulative CH4 emission from early- and late-transplanted plots during wet season, 2002 was 408.77 and 308.58kgha−1 and during the dry season, 2003 was 431.35 and 328.66kgha−1, respectively. Early transplanted seedlings had higher number of tillers and exhibited low soil redox (Eh) potential thereby favouring higher CH4 emission. There was no statistically significant yield reduction due to transplanting of aged seedlings or planting late over that of young seedlings planted early. Our results suggest that in rainfed rice cultivation, as practiced in greater part of Asia and Africa, transplanting late with comparatively aged seedlings could lead to a considerable reduction in CH4 emission without being detrimental to the yield. [Copyright &y& Elsevier]

Methane emissions from the slurry displacement chambers of different fixed dome type biogas plants (Capacity 2 m3) installed in hilly and plain regions of northern India were quantitatively estimated. The slurry temperature in the biogas plants in the hilly areas of Himachal Pradesh at an altitude of 1300 m above mean sea level remains below the lower mesophilic range (16–25 °C) during most part of the year. Difference in the ambient temperature under the two climatic conditions of Hills and plain regions affects the CH4 flux. Methane fluxes from the plants ranged between 7 and 120 g m-2 d-1. In northern plain, temperature remains warm (21–33 °C) throughout the year except during winter (December to January) when there is a steep fall. Seasonal emission of CH4 ranged between 10 and 178 g m-2 d-1. The annual average methane emission from the biogas plants in plain areas was 83.1 g m-2 d-1 as compared to 43.1 g m-2 d-1in the hilly areas. Annual contribution per plant to the global methane budget from a fixed dome biogas plant (Cap 2 m3) in plain region of northern India was 53.2 kg as compared 22.3 kg in hilly area. [Copyright &y& Elsevier]

Methane (CH4) is one of the important greenhouse gases accounting for 15% of the total enhanced greenhouse effect. Rice (Oryza sativa L.)–wheat (Triticum aestivum L.) cropping system is the most dominating cropping system in the Indo-Gangetic plains (IGPs) of India occupying 10.5 million ha of productive land could be a major source of atmospheric CH4. Effect of irrigation, urea, farmyard manure (FYM), and dicyandiamide (DCD) on emission of CH4 from an alluvial soil (Ustochrept) in rice–wheat cropping system was studied using the closed chamber technique. Total emission of CH4 from the rice–wheat systems ranged from 16.2 kg ha−1 in the control treatment to 36.5 kg ha−1 in urea plus FYM treatment with an average emission of 20.8 kg CH4 ha−1. Continuously saturated soil in rice gave higher CH4 emission compared to intermittent wetting and drying soil condition but the yields were lowered. Application of DCD with urea reduced emission of CH4 in rice–wheat system to 70%, while substituting 50% of inorganic N with FYM increased emission to 172% compared to application of entire amount of N through urea. In wheat negative fluxes of CH4 up to 0.1 kg ha−1 per day was recorded. There was no difference in CH4 flux in wheat between the various irrigation treatments. In the most common fertilizer practice in IGPs the emission of CH4 is 21.2 kg ha−1. Intermittent wetting and drying of soil in rice has a potential to reduce the emission. [Copyright &y& Elsevier]

Rising rate of MSW generation and unscientific disposal in the open dumping sites are responsible for emission of high concentrations of methane in developing countries. IPCC Default method (DM), First-order decay (FOD) and LandGEM were used to estimate methane emissions from the unengineered landfill sites of Delhi-Okhla, Bhalswa and Ghazipur between 1984 and 2015. During the period, the total CH 4 emissions was found to be 1288.99, 311.18, 779.32 Gg from the 3 landfill sites of Delhi as predicted by DM, FOD and LandGEM respectively. The energy generation potential from methane for the year 2015 was found to vary from 4.16 × 10 8 to 9.86 × 10 8  MJ for Ghazipur, 2.08 × 10 8 to 4.06 × 10 8  MJ for Okhla and 3.42 × 10 8 to 8.11 × 10 8  MJ for Bhalswa. Efficient utilization of methane from the landfills as an energy source can be a sustainable waste management option., (Copyright © 2018 Elsevier Ltd. All rights reserved.)