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    Effects of alternate wetting and drying technique on greenhouse gas emissions from irrigated rice paddy in Central Luzon, Philippines
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    Abstract:
    Alternate wetting and drying (AWD) technique has been widely reported to reduce methane (CH4) emission from irrigated rice paddies. However, little is known about its feasibility in an environment that has distinct weather conditions involving tropical wet season (WS). To investigate the AWD's feasibility in terms of reducing greenhouse gas (GHG) emissions both in dry season (DS) and WS, 3-year field experiments were conducted in Central Luzon, Philippines. Three treatments of water management were continuous flooding (CF), flooding when surface water level naturally declines to 15 cm below the soil surface (AWD), and site-specific AWD that modified the criteria of soil drying (AWDS). Methane and nitrous oxide (N2O) fluxes were measured using a closed chamber method, and the global warming potential (GWP) of the two GHGs was calculated. Rice grain yield did not significantly differ among treatments. In accordance with the previous findings, the seasonal total CH4 emission was significantly greater in WS than in DS. The effect of treatment was significant, but the reduction rate by AWD was just 1.7% compared to CF. The seasonal total N2O emission was significantly affected by cropping season and treatment. The AWD increased the N2O emission by 97%, especially in DS. The resultant GWP did not significantly differ among three treatments. The results indicate that the AWD and AWDS with the current settings were insufficient to reduce the annual GHG emissions in this site. However, fragmentary results obtained in the last DS suggest that an earlier rice residue incorporation and keeping dry soil conditions in the preceding fallow season is effective in reducing CH4 emission in combination with an earlier implementation of AWD.
    Keywords:
    Paddy field
    Nitrous oxide
    Dry season
    Growing season
    Global-warming potential
    A field experiment was conducted in double rice area to figure out the influence of different rice straw treatments(rice straw removing +NPK,rice straw incorporated into the soil(RS)+NPK,rice straw burned in situ(BIS)+NPK) on the greenhouse gases emission from paddy fields.The results showed that RS+NPK treatment increased the CH4 emission and decreased the N2O emission significantly compared with NPK treatment,while BIS+NPK treatment reduced CH4 and N2O emission during the double rice growing season.N2O emission of RS+NPK and BIS+NPK treatments had no significant difference.CH4 emission from burning activity was equivalent to that from rice field,while N2O emission accounted for a great proportion of total N2O emission during the growing period,90.1% and 53.4%,respectively.The total GHG emission of different treatment is RS+NPKNPKBIS+NPK.A similar order was found for emission intensity(CO2 e/t grain yield).
    Paddy field
    Rice straw
    Emission intensity
    Citations (6)
    Wet season
    Dry season
    Swamp
    Paddy field
    Archipelago
    Dry land
    Citations (1)
    Methane is one of the main souse of global warming and its emission from rice paddy field is a big issue. To fully investigate the special and temporal distribution of methane emission from rice paddy, we utilize the rice crop calendar mapping and ground water coverage data from satellite observation for IPCC 2006 guidelines. Then, global methane emission inventory from rice paddy is estimated. Comparison between atmospheric methane concentration from GOSAT and estimated methane emission inventory in regional scale is done and positive relationship between them is found.
    Paddy field
    Global-warming potential
    Atmospheric methane
    Methane gas
    Emission inventory
    Methane Emissions
    Greenhouse gas(GHG)emissions from agricultural production systems contribute largely to global warming. A field experiment was conducted to examine GHG emissions under three different fertilization practices(CT-urea alone, MT-80% urea plus 20% manure and OT-manure alone)in Shanghai suburb, China. Carbon dioxide, methane and nitrous oxide were collected and measured by static chambergas chromatography system. Compared to the control(CK), fertilization significantly increased carbon dioxide emission from paddy field, but no differences were found between fertilization treatments. Organic manure significantly increased methane emission, but greatly decreased nitrous oxide emission from paddy field. During the whole rice season, CK had the lowest seasonal Global Warming Potential(GWP)with14 852 kg CO2·hm-2. Urea alone and organic manure alone and their combinations increased seasonal GWP by 86.9%, 134.3% and 111.5%,respectively, as compared with CK. The observed data demonstrate that fertilization could increase GHG emission and GWP from paddy field.
    Nitrous oxide
    Paddy field
    Global-warming potential
    Manure management
    Citations (3)
    Summary Although often felt to be relatively innocuous, nitrous oxide can have significant metabolic effects in settings of abnormal vitamin B 12 and B 12 ‐related metabolism in children. These conditions can be genetic or environmental. Symptoms may not appear until days to weeks after exposure to nitrous oxide. Although overt genetic diseases are relatively uncommon, the implications of nitrous oxide interactions with much more frequent but less symptomatically obvious single nucleotide polymorphisms are potentially more concerning. In addition, nitrous oxide can have direct and differing neurotoxic effects on both immature and aged brain, the clinical impact of which remains undetermined.
    Nitrous oxide
    The field experiment of CH4 and N2O emission by straw incorporated to paddy field(RS) and biochar incorporated to paddy field(BC) during late rice growth stages was studied in Hunan province using the static chamber-gas chromatograph techniques.Results showed that Amount of CH4 emissions by treatments of RS and BC were increased by 24.70%(P0.05) and 6.32% respectively,compared with chemical fertilization treatment(CF),but amount of N2O emission was reduced by 37.08%(P0.05) and 37.61%(P0.05),respectively.Amount of CH4 emissions by BC treatment was decrease by 14.74%(P0.05) than that of RS treatment.According to Global Warming Potential(GWP) converted by CH4 and N2O emissions at one hundred years scale,the result showed that GWP of unit yields arranged by RS CK BC CF.Therefore,biochar returned to field not only was stabilized rice yields,but also reduced CH4 and N2O emission of later rice,and application of BC has a well environment benefits.
    Paddy field
    Rice straw
    Global-warming potential
    Citations (1)