Fraunhofer-Institut für Atmosphärische Umweltforschung IFU

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  • Publication
    Characterization of methane emissions from rice fields in Asia. II. Differences among irrigated, rainfed, and deepwater rice
    ( 2000)
    Wassmann, R.
    ;
    Neue, H.U.
    ;
    Lantin, R.S.
    ;
    Makarim, K.
    ;
    Chareonsilp, N.
    ;
    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
    A sampling technique for the determination of dissolved methane in soil solution
    ( 2000)
    Alberto, M.C.R.
    ;
    Arah, J.R.M.
    ;
    Neue, H.U.
    ;
    Wassmann, R.
    ;
    Lantin, R.S.
    ;
    Aduna, J.B.
    ;
    Bronson, K.F.
    A sampling technique was developed to sample floodwater and soil solution from wetland ricefields for the determination of dissolved CH4. The method was compared with the soil core method used in the measurement of entrapped CH4. This was done to assess if dissolved CH4 determination could be an alternative to soil-entrapped CH4 measurements since the latter is time-consuming. laborious and destructive in nature. The dynamics of both dissolved CH4 and entrapped CH4 follow the same seasonal pattern. They have the same degree of spatial and temporal variability. However, the sampling procedure developed for the determination of dissolved CH4 is relatively simple, easy and convenient compared to that for soil-entrapped CH4 measurements. It also allows in-situ solution sampling at different soil depths. Therefore, it is recommended that dissolved CH4 measurements can be an alternative to soil-entrapped CH4 determinations.
  • 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.
    ;
    Chen, W.
    ;
    Duan, B.W.
    ;
    Guo, W.M.
    ;
    Lu, Y.
    ;
    Lantin, R.S.
    ;
    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
    Simulation of methane production in anaerobic rice soils by a simple two-pool model
    ( 2000)
    Lu, Y.
    ;
    Arah, J.R.M.
    ;
    Wassmann, R.
    ;
    Neue, H.U.
    Methane (CH sub 4) is produced in flooded rice fields by anaerobic decomposition of applied organic residues, rootderived materials and native soil organic matter (SOM). Since CH sub 4 is an important greenhouse gas it is important to understand, and to be able to model, the processes which produce it. Anoxic incubation of soils employed in the cultivation of irrigated rice, with and without the addition of various potentially-available organic substrates, provides information on potential CH sub 4 emissions which can be incorporated into process-based models. In this study, a simple two-pool model is employed to simulate the CH sub 4 production of a number of anaerobically-incubated rice soils, and their responses to amendment with a variety of organic substrates. The model differs from most accounts of SOM transformation in that kinetics are microbially-mediated rather than first-order. Simulation yields a reproduction of the general trends of CH sub 4 production in response to amendments of acetate, glucose and lice straw.
  • Publication
    Dynamics of dissolved organic carbon and methane emissions in a flooded rice soil
    ( 2000)
    Lu, Y.H.
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    Wassmann, R.
    ;
    Neue, H.U.
    ;
    Huang, C.Y.
  • 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.
    ;
    Li, Z.
    ;
    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.