Fraunhofer-Institut für Atmosphärische Umweltforschung IFU

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  • Publication
    Methane emission from irrigated and intensively managed rice fields in Central Luzon (Philippines)
    ( 2000)
    Corton, T.M.
    ;
    Bajita, J.B.
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    Grospe, F.S.
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    Pamplona, R.R.
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    Asis, C.A.
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    Wassmann, R.
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    Lantin, R.S.
    ;
    Buendia, L.V.
    Methane (CH4) emissions were measured with an automated system in Central Luzon, the major rice producing area of the Philippines. Emission records covered nine consecutive seasons from 1994 to 1998 and showed a distinct seasonal pattern: an early flush of CH4 before transplanting, an increasing trend in emission rates reaching Maximum toward grain ripening, and a second flush after water is withdrawn prior to harvesting. The local practice of crop Management, which consists of continuous flooding and urea application, resulted in 79-184 mg CH4 ma high -2 d high -1 in the dry season (DS) and 269-503 mg CH4 m high -2 d high -1 in the wet season (WS). The higher emissions in the WS may be attributed to more labile carbon accumulation during the dry fallow period before the WS cropping as shown by higher % organic C. Incorporation of sulfate into the soil reduced CH4 emission rates. The use of ammonium sulfate as N fertilizer in place of urea resulted in a 25-36 % reduction in CH4 emissions. Phosphogypsum reduced CH4 emissions by 72 % when applied in combination with urea fertilizer. Midseason drainage reduced CH4 emission by 43 %, which can be explained by the influx of oxygen into the soil. The practice of direct seeding instead of transplanting resulted in a 16-54 % reduction in CH4 emission, but the mechanisms for the reducing effect are not clear. Addition of rice straw compost increased CH4 emission by only 23-30 % as compared with the 162-250 % increase in emissions with the use of fresh rice straw. Chicken manure combined with urea did not increase CH4 emission. Fresh rice straw has wider C/N (25 to 45) while rice straw compost has C/N = 6 to 10 and chicken manure has C/N = 5 to 8. Modifications in inorganic and organic fertilizer management and water regime did not adversely affect grain yield and are therefore potential mitigation options. Direct seeding has a lower yield potential than transplanting but is getting increasingly popular among farmers due to labor savings. Combined with a package of technologies, CH4 emission can best be reduced by (1) the practice of midseason drainage instead of continuous flooding, (2) the use of sulfate-containing fertilizers such as ammonium sulfate and phosphogypsum combined with urea; (3) direct seeding crop establishment; and (4) use of low C/N organic fertilizer such as chicken manure and rice straw compost.
  • Publication
    Characterization of methane emissions from rice fields in Asia. II. Differences among irrigated, rainfed, and deepwater rice
    ( 2000)
    Wassmann, R.
    ;
    Neue, H.U.
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    Lantin, R.S.
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    Makarim, K.
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    Chareonsilp, N.
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    Buendia, L.V.
    ;
    Rennenberg, H.
    Methane (CH sub4) emission rates were recorded automatically using the closed chamber technique in major rice-growing areas of Southeast Asia. The three experimental sites covered different ecosystems of wetland rice -irrigated, rainfed, and deepwater rice - using only mineral fertilizers (for this comparison). In Jakenan (Indonesia), the local water regime in rainfed rice encompassed a gradual increase (wet season) and a gradual decrease (dry season) in floodwater levels. Emissions rates accumulated to 52 and 91 kg CH sub 4 ha high -1 season high -1 corresponding to approximately 40 % of emissions from irrigated rice in each season. Distinct drainage periods within the season can drastically reduce Ch sub 4 emissions to less than 30 kg CH sub 4 ha high -1 season high -1 as shown in Los Banos (Philippines). The reduction effect of this water regime as compared with irrigated rice varied from 20 % to 80 % from season to season. Methane fluxes from deepwater rice in Prachinburi (Thailand) were lower than from irrigated rice but accumulated to equally high seasonal values, i. e., about 99 kg CH sub 4 ha high -1 season high -1, due to longer seasons and assured periods of flooding. Rice ecosystems with continuous flooding were characterized by anaerobic conditions in the soil. These conditions commonly found in irrigated and deepwater rice favored CH sub 4 emissions. Temporary aeration of flooded rice soils. which is generic in rainfed rice, reduced emission rates due to low CH sub 4 production and high CH sub 4 oxidation. Based on these findings and the global distribution of rice area, irrigated rice accounts globally for 70 - 80 % of CH sub 4 from the global rice area. Rainfed rice (about 15 %) and deepwater rice (about 10 %) have much lower shares. In turn, irrigated rice represents the most promising target for mitigation strategies. Proper water management could reduce CH sub 4 emission without affecting yields.
  • Publication
    Crop management affecting methane emissions from irrigated and rainfed rice in Central Java (Indonesia)
    ( 2000)
    Setyanto, P.
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    Makarim, A.K.
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    Fagi, A.M.
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    Wassmann, R.
    ;
    Buendia, L.V.
    Methane (CH sub 4) emissions were determined from 1993 to 1998 using an automated closed chamber technique in irrigated and rainfed rice. In Jakenan (Central Java), the tow consecutive crops encompass a gradient from low to heavy rainfall (wet season crop) and from heavy to low rainfall (dry season crop), respectively. Rainfed rice was characterized by very low emission at the onset of the wet season and the end of the dry season. Persistent flooding in irrigated fields resulted in relatively high emission rates throughout the two seasons. Average emission in rainfed rice varied between 19 and 123 mg Ch sub 4 m high -2 d high -1, whereas average in irrigated rice ranged from 71 to 217 mg CH sub 4 m high -2 d high -1. the impact of organic manure was relatively small in rained rice. In the wet season, farmyard manure (FYM) was completely decomposed before CH sub 4 emission was initiated; rice straw resulted in 40 % increase in emission rates during this cropping season. In the dry season, intensive flooding in the early stage promoted high emissions from organically fertilized plots; seasonal emissions of FYM and rice straw increased by 72 % and 37 %, respectively, as compared with mineral fertilizer. Four different rice cultivars were tested in irrigated rice. Average emission rates differed from season to season, but the total emissions showed a consistent ranking in wet and dry season, depending on season length. The early-maturing Dodokan had the lowest emissions (101 and 52 kg CH sub 4 ha high -1) and the late-maturing Cisadane had the highest emissions (142 and 116 kg CH sub 4 ha high -1). The high-yielding varieties IR64 and Memberamo had moderately high emission rates. These findings provide important clues for developing specific mitigation strategies for irrigated and rainfed rice.
  • Publication
    Characterization of methane emissions from rice fields in Asia. I. Comparison among field sites in five countries
    ( 2000)
    Wassmann, R.
    ;
    Neue, H.U.
    ;
    Lantin, R.S.
    ;
    Buendia, L.V.
    ;
    Rennenberg, H.
    The Interregional Research Program on Methane Emissions from Rice Fields established a network of eight measuring stations in five Asian countries. These stations covered different environments and encompassed varying practices in crop management. All stations were equipped with a closed chamber system designed for frequent sampling and long-term measurements of emission rates. Even under identical treatment - e. g., continuous flooding and no organic fertilizers - average emission rates varied from 15 to 200 kg CH sub 4 ha high -1 season high -1. Low temperatures limited CH sub 4 emissions in temperate and subtropical stations such as northern China and northern India. Differences observed under given climates, (e. g., within the tropics) indicated the importance of soil properties in regulating the CH sub 4 emission potential. However, local variations in crop management superseded the impact o soil- and climate-related factors. This resulted in uniformly high emission rates of about 300 kg CH sub 4 ha high -1 season high -1 for the irrigated rice stations in the Philippines (Maligaya) and China (Beijing and Hangzhou). The station in northern India (Delhi) was characterized by exceptionally low emission rates of less than 20 kg CH sub 4 ha high -1 season high -1 under local practice. These findings also suggest opportunities for reducing CH sub 4 emission through a deliberate modification of cultural practice for most irrigated rice fields.
  • Publication
    Mechanisms of crop management impact on methane emissions from rice fields in Los Banos, Philippines
    ( 2000)
    Wassmann, R.
    ;
    Buendia, L.V.
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    Lantin, R.S.
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    Bueno, C.S.
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    Lubigan, L.A.
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    Umali, A.
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    Nocon, N.N.
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    Javellana, A.M.
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    Neue, H.U.
    This article comprises 4 yr of field experiments on methane (CH sub 4) emissions from rice fields conducted at Los Banos, Philippines. The experimental layout allowed automated measurements of CH sub 4 emissions as affected by water regime, soil amendments (mineral and organic), and cultivars. In addition to emission records over 24 h, ebullition and dissolved CH sub 4 in soil solution were recorded in weekly intervals. Emission rates varied in a very wide range from 4 to 634 kg CH sub 4 ha high -1, depending on season and crop management. In the 1994 and 1996 experiments, field drying at midtellering reduced CH sub 4 emissions by 15 - 80 % as compared with continuous flooding, without a significant effect on grain yield. The net impact of midtellering drainage was diminished when (i) rainfall was strong during the drainage period and (ii) emissions were suppressed by very low levels of organic substrate in the soil Five cultivars were tested in the 1995 dry and wet season. The cultivar IR72 gave higher CH sub 4 emissions than the other cultivars including the new plant type (IR65597) with an enhanced yield potential. Incorporation of rice straw into the soil resulted in an early peak of CH sub 4 emission rates. About 66 % of the total seasonal emission from rice straw-treated plots was emitted during the vegetative stage. Methane fluxes generated from the application of straw were 34 times higher than those generated with the use of urea. Application of green manure (Sesbania rostrata) gave only threefold increase in emission as compared with urea-treated plots. Application of ammonium sulfate significantly reduced seasonal emission as compared with urea application. Correlation between emissions and combined dissolved CH sub 4 concentrations (from 0 to 20 cm) gave a significant R high2 of 0.95 (urea + rice straw), and 0.93 (urea + Sesbania), whereas correlation with dissolved CH sub 4 in the inorganically fertilized soils was inconsistent. A highly significant correlation (R high 2 is equal 0.93) existed between emission and ebullition from plots treated with rice straw. These findings may stimulate further development of diagnostic tools for easy and reliable determination of CH sub 4 emission potentials under different crop management practices.
  • Publication
    Characterization of methane emissions from rice fields in Asia. III. Mitigation options and future research needs
    ( 2000)
    Wassmann, R.
    ;
    Lantin, R.S.
    ;
    Neue, H.U.
    ;
    Buendia, L.V.
    ;
    Corton, T.M.
    ;
    Lu, Y.
    Methane (CH sub 4) emissions from rice fields were determined using automated measurement systems in China, India, Indonesia, Thailand, and the Philippines. Mitigation options were assessed separately for different baseline practices of irrigated rice, rainfed, and deepwater rice. Irrigated rice is the largest source of CH sub 4 and also offers the most options to modify crop management for reducing these emissions. Optimizing irrigation patterns by additional drainage periods in the field or an early timing of midseason drainage accounted for 7 - 80 % of CH sub 4 emissions of the respective baseline practice. In baseline practices with high organic amendments, use of compost (58 - 63 %), biogas residues (10 - 16 %), and direct wet seeding (16 - 22 %) should be considered mitigation options. In baseline practices using prilled urea as sole N source, use of ammonium sulfate could reduce CH sub 4 emission by 10 - 67 %. In all rice ecosystems, CH sub 4 emissions can be reduced b fallow incorporation (11 %) and mulching (11 %) of rice straw as well as addition of phosphogypsum (9 - 73 %). However, in rainfed and deepwater rice, mitigation options are very limited in both number and potential gains. The assessment of these crop management options includes their total factor productivity and possible adverse effects. Due to higher nitrous oxide (N sub 2 O) emissions, changes in water regime are only recommended for rice systems with high baseline emissions of CH sub 4. Key objectives of future research are identifying and characterizing high-emitting rice systems, developing site-specific technology packages, ascertaining synergies with productivity, and accounting for N sub 2 O emissions.
  • Publication
    Using a crop/soil simulation model and GIS techniques to assess methane emissions from rice fields in Asia. II. Model validation and sensitivity analysis
    ( 2000)
    Matthews, R.B.
    ;
    Wassmann, R.
    ;
    Buendia, L.V.
    ;
    Knox, J.W.
    The MERES (Methane Emissions from Rice EcoSystems) simulation model was tested using experimental data from IRRI and Maligaya in the Philippines and from Hangzhou in China. There was good agreement between simulated and observed values of total aboveground biomass, root weight, grain yield, and seasonal methane (CH sub 4) emissions. The importance of the contribution of the rice crop to CH sub 4 emissions was highlighted. Rhizodeposition (root exudation and root death) was predicted to contribute about 380 kg C ha high -1 of methanogenic substrate over the season, representing 37 % of the total methanogenic substrate from all sources when no organic amendments were added. A further 225 kg C ha high -1 (22 %) was predicted to come from previous crop residues, giving a total of around 60 % originating from the rice crop, with the remaining 41 % coming from the humic fraction of the soil organic matter (SOM). Sensitivity analysis suggested that the parameter representing transmissivity to gaseous transfer per unit root length (? sub r) was important in determining seasonal CH sub 4 emissions. As this transmissivity increased, more O sub 2 was able to diffuse to the rhizosphere, so that CH sub 4 production by methanogens was reduced and more CH sub 4 was oxidized by methanotrophs. These effects outweighed the opposing influence of increased rate of transport of CH sub 4 through the plant, so that the overall effect was to reduce the amount of CH sub 4 emitted over the season. Varying the root-shoot ratio of the crop was predicted to have little effect on seasonal emissions, the increased rates of rhizodeposition being counteracted by the increased rates of O sub 2 diffusion to the rhizosphere. Increasing the length of a midseason drainage period reduced CH sub 4 emissions significantly, but periods longer than 6 - 7 d also decreased rice yields. Organic amendments with low C/N were predicted to be more beneficial, both in terms of enhancing crop yields and reducing CH sub 4 emissions, even when the same amount of C was applied. This was due to higher rates of immobilization of C into microbial biomass, removing it temporarily as a methanogenic substrate.
  • Publication
    Using a crop/soil simulation model and GIS techniques to assess methane emissions from rice fields in Asia. IV. Upscaling to national levels
    ( 2000)
    Matthews, R.B.
    ;
    Wassmann, R.
    ;
    Knox, J.W.
    ;
    Buendia, L.V.
    The process-based crop/soil model MERES (Methane Emissions from Rice EcoSystems) was used together with daily weather data, spatial soil data, and rice-growing statistics to estimate the annual methane (CH sub 4) emissions from China, India, Indonesia, Philippines, and Thailand under various crop management scenarios. Four crop management scenarios were considered: (a) a 'baseline' scenario assuming no addition of organic amendments or field drainage during the growing season, (b) addition of 3,000 kg DM ha high -1 of green manure at the start of the season but no field drainage, (c) no organic amendments but drainage of the field for a 14-d period in the middle of the season and again at the end of the season, and (d) addition of 3,000 kg DM ha high -1 of green manure and field drainage in the middle and end of the season. For each scenario, simulations were made at each location for irrigated and rainfed rice ecosystems in the main rice-growing season, and for irrigated rice in the second (or 'dry') season. Overall annual emissions (Tg CH sub 4 yr high -1) for a province/district were calculated by multiplying the rates of CH sub 4 emission (kg CH sub 4 ha high -1 yr high -1) by the area of rice grown in each ecosystem and in each season obtained from the Huke and Huke (1997) database of rice production. Using the baseline scenario, annual CH sub 4 emissions for China, India, Indonesia, Philippines, and Thailand were calculated to be 3.73, 2.14, 1.65, 0.14, and 0.18 Tg CH sub 4 yr high -1, respectively. Addition of 3,000 kg DM ha high -1 green manure at the start of the season increased emissions by an average of 128 % across the five countries, with a range of 74 - 259 %. Drainage of the field in the middle and at the end of the season reduced emissions by an average of 13 % across the five countries, with a range of -10 % to -39 %. The combination of organic amendments and field drainage resulted in an increase in emissions by an average of 86 % across the five countries, with a range of 15 - 176 %. The sum of CH sub 4 emissions from these five countries, comprising about 70 % of the global rice area, ranged from 6.49 to 17.42 Tg CH sub 4 yr high -1, depending on the crop management scenario.
  • Publication
    A four-year record of methane emissions from irrigated rice fields in the Beijing region of China
    ( 2000)
    Wang, Z.Y.
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    Xu, Y.C.
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    Li, Z.
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    Guo, Y.X.
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    Wassmann, R.
    ;
    Neue, H.U.
    ;
    Lantin, R.S.
    ;
    Buendia, L.V.
    ;
    Ding, Y.P.
    ;
    Wang, Z.Z.
    Methane (CH sub 4) emissions from irrigated rice fields were measured using an automatic sampling-measuring system with closed chamber method in 1995-98. Average emission rates ranged from 11 to 364 mg m high -2 d high -1 depending on season, water regime, and fertilizer application. Crop management typical for this region (i. e. midseason drainage and organic/mineral fertilizer application) resulted in emission of 279 and 139 mg CH sub 4 m high -2 d high -1 in 1995 and 1997, respectively. This roughly corresponds to emissions observed in other rice-growing areas of China. Emissions were very intense during the tillering stage, which accounted for 85 % of total annual emission, but these were suppressed by low temperature in the late stage of the season. The local irrigation practice of drying at midseason reduced emission rates by 23 %, as compared with continuous flooding. Further reduction of CH sub 4 emissions could be attained by (1) alternate flooding/drying, (2) shifting the drainage period to an earlier stage, or (3) splitting drainage into two phases (of which one is in an earlier stage). Emission rates were extremely sensitive to organic amendments: seasonal emissions from fields treated with pig manure were 15-35 times higher than those treated with ammonium sulfate in the corresponding season. On the basis of identical carbon inputs, CH sub 4 emission potential varied among organic amendments. Rice straw had higher emissions than cattle manure but lower emissions than pig manure. Use of cultivar Zhongzhuo (modern japonica) reduced CH sub 4 emission by 45 % and 50 %, in 1995 and 1997, respectively, as compared with Jingyou (japonica hybrid) and Zhonghua (tall japonica). The results give evidence That CH sub 4 emissions from rice fields in northern China can be reduced by a package of crop management options without affecting yields.
  • Publication
    An efficient sampling strategy for estimating methane emission from rice field
    ( 1998)
    Buendia, L.V.
    ;
    Neue, H.U.
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    Wassmann, R.
    ;
    Lantin, R.S.
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    Javellana, A.M.
    ;
    Arah, J.
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    Wang, Z.
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    Wanfang, L.
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    Makarim, A.
    ;
    Corton, T.M.
    ;
    Charoensilp, N.
    Rice fields are a major source of atmospheric methane. Evaluation of management strategies designed to reduce emissions while maintaining or enhancing yield requires data on fluxes from a range of ecosystems and climatic zones. Automated closed chamber systems are too expensive for this purpose everywhere, but analysis of the patterns of diel and seasonal flux variation reveal an optimal less-intensive sampling strategies for use with manually operated chambers. Such an analysis, presented here, suggests that sampling at 0600, 1200, and 1800 h is sufficient to capture most of the diel variation observed throughout the growing season, and that sampling is most important where fluxes are most variable, between flowering and harvest. For a typical 100-day growing season, fluxes should ideally be measured at around 10, 20, 30, 50, 70, 77, 84, 91, and 98 days after planting. The proposed sampling strategy considers seasonal variations in methane emission as influenced by temporal, spatial, and crop management related factors.