Methane Emission From Two Different Rice Ecosystems ( Ahu and Sali ) at Lower Brahmaputra Valley Zone of North East India

Abstract

Abstract.Monocropping of rice is practiced in Assam (situated at north east part of India) throughout the year in different agro-ecosystems (upland and lowland) primarily under rainfed conditions. The estimation of methane emission has been realized investigating high yielding rice varieties viz. Ranjit and Mahsuri, grown under two different agro-ecosystems at Lower Brahmaputra Valley Zone of Assam with sandy to sandy loam type of soil. Variety 'Ranjit' grown at monsoon (Sali) rice ecosystem at lowland rainfed condition showed higher seasonal integrated methane flux value compared to variety 'Mahsuri' grown at pre monsoon (Ahu) rice ecosystem. Both varieties showed two methane peaks, one at the active tillering stage and the second at the reproductive stage of the crop. The observed variation in methane emission peaks are contributed mainly by physiological characteristics of the rice plant such as leaf numbers, tiller numbers, plant height, root shoot biomass and leaf area index. Statistical analysis of these parameters showed a positive correlation with methane emission. These physiological parameters are in turn governed by plant genotypes and environment i.e., the field water availability and climatological factors (rainfall and temperature) during the growing season. While comparing the two ecosystems it was found that methane emission is significantly less from upland rainfed rice ecosystem and this ecosystem can be considered a suitable option for biological mitigation of methane from rice paddies.

Site-specific feasibility of alternate wetting and drying as a greenhouse gas mitigation option in irrigated rice fields in Southeast Asia: a synthesis

“…In Muñoz, a large increase in N 2 O emissions under AWD during DS occurred just after N fertilization, especially when the soil was not irrigated (Sibayan et al 2018). In the loamy soils of Hue and Jakenan, the N 2 O emissions were minimized by keeping soil flooded after N fertilizer application as shown in a study by Furukawa et al (2007).…”

“…Global and regional estimates of GHG emissions from rice fields vary greatly depending on the assumptions made on the relative importance of different factors affecting the emissions. Studies have shown spatial variations in CH 4 emissions from continuously flooded rice fields with varying soil properties including sand and clay contents, aeration, compaction, moisture, pH, organic matter, available N, C/N ratio, and also with changes in soil management, crop rotation, and climates (Adhya et al 1994;Gogoi et al 2008;Inubushi et al 1997;Kimura et al 1991;Kumar and Viyol 2009;Minami and Neue 1994;Wassmann et al 2000aWassmann et al , 2000bYang and Chang 1998;Yagi and Minami 1990;Yao et al 1999). The Intergovernmental Panel on Climate Change (IPCC 2006) has given a baseline emission factor for CH 4 (EF CH4 ) of 1.3 kg CH 4 ha −1 d −1 (with error range of 0.8-2.2), estimated by statistical analysis of available data (Yan et al 2005) from continuously flooded rice fields without organic amendments.…”

Fingerprint of rice paddies in spatial–temporal dynamics of atmospheric methane concentration in monsoon Asia

“…Source data are provided as a Source Data file. studies found a strong correlation between daily CH 4 flux and rice plant biomass, which suggested that methane flux in rice paddies is affected by rice growth and development [37][38][39][40][41][42][43][44] . Here, we compared the observed CH 4 emission and EVI at eight paddy rice sites [25][26][27]41,42,[45][46][47] , and the results confirmed their consistency in terms of seasonality ( Supplementary Fig.…”

Comparison of Methane Emission from Conventional and Modified Paddy Cultivation in Malaysia

“…However, at the second peak the carbon source for methanogens were available from the plant related organic matters entering into the soil from rice roots (Khosa et al, 2011). Therefore, more carbon source was available for methanogenic activity at 68 DAT and thus, resulted in a higher methane emission than 46 DAT (Neue et al, 1996;Gogoi et al, 2008). After drying the soil near the end of growing season (88 DAT) the methane emission lessened with a steep decline so that at harvest time we could not observe any methane emission.…”

“…The maximum methane emissions in MCs have been observed at panicle initiation stage which coincides with 71 DAT, with a significantly lower amount (3.29 mg CH 4 m -2 d -1 ) in comparison with C (8.91 mg CH 4 m -2 d -1 ). It seems that this increase was in consequence of decomposition of root exudates and rice plants' litters (Gogoi et al, 2008). On the other hand, two peaks were recorded in C. the first peak at 46 DAT and the second one at 68 DAT.…”