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.
    ;
    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an increasing trend in emission rates reaching Maximum toward grain ripening, and a second flush after water is withdrawn prior to harvesting.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
    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.
    ;
    Lantin, R.S.
    ;
    Bueno, C.S.
    ;
    Lubigan, L.A.
    ;
    Umali, A.
    ;
    Nocon, N.N.
    ;
    Javellana, A.M.
    ;
    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
    Methane emissions and mitigation options in irrigated rice fields in southeast China
    ( 2000)
    Lu, W.F.
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    Chen, W.
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    Duan, B.W.
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    Guo, W.M.
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    Lu, Y.
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    Lantin, R.S.
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    Wassmann, R.
    ;
    Neue, H.U.
    Methane (CH sub 4) emissions from rice fields were monitored in Hangzhou, China, from 1995 to 1998 by an automatic measurement system based on the "closed chamber technique." The impacts of water management, organic inputs, and cultivars on CH sub 4 emission were evaluated. Under the local crop management system, seasonal emissions ranging from 53 to 557 kg CH sub 4 ha high -1 were observed with an average value of 182 kg CH sub 4 ha high -1. Methane emission patterns differed among rice seasons and were generally governed. by temperature changes. Emissions showed an increasing trend in early rice and a decreasing trend in late rice. In a single rice field, CH sub 4 emissions increased during the first half of the growing period and decreased during the second half. Drainage was a major modifier of seasonal CH sub 4 emission pattern. The local practice of midseason drainage reduced CH sub 4 emissions by 44 % as compared with continuous flooding; CH sub 4 emissions could further be reduced by intermittent irrigation, yielding a 30 % reduction as compared with midseason drainage. The incorporation of organic amendments promoted CH sub 4 emission, but the amount of emission varied with the type of organic material and application method. Methane emission from fields where biogas residue was applied was 10 - 16 % lower than those given the same quantity (based on N content) of pig manure. Rice straw applied before the winter fallow period reduced CH sub 4 emission by 11 % as compared with that obtained from fields to which the same amount of rice straw was applied during field preparation. Broadcasting of straw instead of incorporation into the soil showed less emission (by 12 %). Cultivar selection influenced CH sub 4 emission, but the differences were smaller than those among organic treatments and water regimes. Modifications in water regime and organic inputs were identified as promising mitigation options in southeast China.
  • 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
    A four-year record of methane emissions from irrigated rice fields in the Beijing region of China
    ( 2000)
    Wang, Z.Y.
    ;
    Xu, Y.C.
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    Li, Z.
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    Guo, Y.X.
    ;
    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
    Methane emission from deepwater rice fields in Thailand
    ( 2000)
    Chareonsilp, N.
    ;
    Buddhaboon, C.
    ;
    Promnart, P.
    ;
    Wassmann, R.
    ;
    Lantin, R.S.
    Field experiments were conducted in the Prachinburi Rice Research Center (Thailand) from 1994 to 1998. The major objective was to study methane (CH4) emission from deepwater rice as affected by different crop management. Irrigated rice was investigated in adjacent plots, mainly for comparison purposes. The 4-yr average in CH4 emission from deepwater rice with straw ash (burned straw) treatment was 46 mg m high -2 d high -1 and total emission was 98 kg ha high -1 yr high -1. For irrigated rice, the average emission rate and total emission for the straw ash treatment was 79 mg m high -2 d high -1 and 74 kg ha high -1 yr high -1, respectively. Low emission rates may partially be related to acid sulfate soil of the experimental site. Without organic amendment, the seasonal pattern of CH4 emission from deepwater rice was correlated with an increase in biomass of rice plants. Emission rates from deepwater rice depend on the production of biomass and the straw management as well. Methane emission was greatest with straw incorporation, followed by straw compost incorporation, zero-tillage with straw mulching, and least with straw ash incorporation. The seasonal pattern of CH4 ebullition in deepwater rice was consistent with seasonal emission, and total ebullition corresponded to 50 % of total emission. Dissolved CH4 concentrations in the surface soil (0 - 5 cm) were similar to those in the subsoil (5 - 15 cm), and the seasonal fluctuation of dissolved CH4 was also consistent with the seasonal CH4 emission. Increase in plant density and biomass of irrigated rice grown by pregerminated seed broadcasting enhanced CH4 emission as compared with transplanting.
  • Publication
    Factors and processes controlling methane emissions from rice fields
    ( 1997)
    Neue, H.U.
    ;
    Wassmann, R.
    ;
    Kludze, H.K.
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    Bujun, W.
    ;
    Lantin, R.S.
    Understanding the major controlling factors of methane emissions from ricefields is critical for estimates of source strengths. This paper reports results on the relationship of different plant characteristics and methane fluxes in ricefields. Methane fluxes in ricefields show distinct diel and seasonal variations. Diel variations are mainly controlled by soil solution temperature and the partial pressure of methane. One or two distinct seasonal maxima are observed in irrigated ricefields. The first is governed by methane production from soil and added organic matter and a second at heading is plant derived. During ripening and maturity, root exudation, root porosity and root oxidation power may control methane emission rates. Rice plants play an important role in methane flux. The aerenchyma conduct methane from the bulk soil into the atmosphere. The amount of carbon utilized in methane formation varied among cultivars. A strong positive effect of rice root exudates on methane product ion imply that cultivar selections for lower methane emissions should not only be based on the gas transport capabilities but also on the quality and quantity of root exudates. Soils show a wide range of methane production potential but no simple correlation between any stable soil property and methane production is evident. Various cultural practices affect methane emissions. Defined aeration periods reduce methane emissions. Soil entrapped methane is released to the atmosphere as a result of soil disturbances. Mineral fertilizers influence methane production and sulfate containing fertilizer decrease methane production. The methane release per m2 from different rice ecosystems follow the order: deepwater rice>irrigated rice>rainfed rice. Abatement strategies may only be accepted if the methane source strength of ricefields is reliably discriminated and if mitigation technologies are in accordance with increased rice production and productivity.