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1.
Characterization of Methane Emissions from Rice Fields in Asia. I. Comparison among Field Sites in Five Countries 总被引:4,自引:0,他引:4
R. Wassmann H.-U. Neue R.S. Lantin L.V. Buendia H. Rennenberg 《Nutrient Cycling in Agroecosystems》2000,58(1-3):1-12
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 CH4 ha–1 season–1. Low temperatures limited CH4 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 CH4 emission potential. However, local variations in crop management superseded the impact of soil- and climate-related factors. This resulted in uniformly high emission rates of about 300 kg CH4 ha–1 season–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 CH4 ha–1 season–1 under local practice. These findings also suggest opportunities for reducing CH4 emission through a deliberate modification of cultural practice for most irrigated rice fields. 相似文献
2.
To reduce the involved uncertainties in the methane budget estimation from rice paddy fields, the methodologies of methane budget estimation have been revised mainly on the basis of measurements undertaken in the Methane Asia Campaign (MAC-98). Studies from other continuous measurements of methane emission from rice paddy fields over last few years in other Asian countries were also used. The Asian Development Bank (ADB) sponsored Methane Asia Campaign (MAC-98) in which India, China, Indonesia, Philippines, Vietnam and Thailand participated during 1998–99.The resulting CH4 measurements have shown that apart from water management, soil organic carbon also plays a significant role in determination of methane emission factors from rice paddy fields. The available data from participating countries reveal that paddy soils can be broadly classified into low soil organic carbon (<0.7%C) and high soil organic carbon (>0.7% C) classes which show average methane emission factors of 12 (5–29) and 36 (22–57) g m–2 respectively for continuously flooded (CF) fields without organic amendments compared to the IPCC–96 emission factor of 20 g m–2. Similarly for irrigated paddy fields with intermittently flooded multiple aeration (IF-MA) without organic amendments, the MAC-98 gives average emission factors of 2 (0.06–3) and 6 (0.6–24) g m–2, respectively, for low and high organic carbon soils compared to IPCC–96 emission factor of 4 (0–10) g m–2. Incorporation of soil organic carbon along with classification based on water management and organic amendments in the estimation of CH4 emissions from rice paddy fields yields more characteristic emission factors for low and high organic carbon soils and is, therefore, capable of reducing uncertainties. 相似文献
3.
A Four-Year Record of Methane Emissions from Irrigated Rice Fields in the Beijing Region of China 总被引:2,自引:0,他引:2
Z.Y. Wang Y.C. Xu Z. Li Y.X. Guo R. Wassmann H.U. Neue R.S. Lantin L.V. Buendia Y.P. Ding Z.Z. Wang 《Nutrient Cycling in Agroecosystems》2000,58(1-3):55-63
Methane (CH4) emissions from irrigated rice fields were measured using an automatic sampling-measuring system with a closed chamber method in 1995–98. Average emission rates ranged from 11 to 364 mg m–2 d–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 CH4 m–2 d–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 mid-season reduced emission rates by 23%, as compared with continuous flooding. Further reduction of CH4 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, CH4 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 CH4 emission by 56% and 50%, in 1995 and 1997, respectively, as compared with Jingyou (japonica hybrid) and Zhonghua (tall japonica). The results give evidence that CH4 emissions from rice fields in northern China can be reduced by a package of crop management options without affecting yields. 相似文献
4.
Methane Emissions and Mitigation Options in Irrigated Rice Fields in Southeast China 总被引:1,自引:0,他引:1
W.F. Lu W. Chen B.W. Duan W.M. Guo Y. Lu R.S. Lantin R. Wassmann H.U. Neue 《Nutrient Cycling in Agroecosystems》2000,58(1-3):65-73
Methane (CH4) 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 CH4 emission were evaluated. Under the local crop management system, seasonal emissions ranging from 53 to 557 kg CH4 ha–1 were observed with an average value of 182 kg CH4 ha–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, CH4 emissions increased during the first half of the growing period and decreased during the second half. Drainage was a major modifier of seasonal CH4 emission pattern. The local practice of midseason drainage reduced CH4 emissions by 44% as compared with continuous flooding; CH4 emissions could further be reduced by intermittent irrigation, yielding a 30% reduction as compared with midseason drainage. The incorporation of organic amendments promoted CH4 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 CH4 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 CH4 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. 相似文献
5.
Methane Emission from Rice Fields at Cuttack, India 总被引:1,自引:0,他引:1
T.K. Adhya K. Bharati S.R. Mohanty B. Ramakrishnan V.R. Rao N. Sethunathan R. Wassmann 《Nutrient Cycling in Agroecosystems》2000,58(1-3):95-105
Methane (CH4) emission from rice fields at Cuttack (State of Orissa, eastern India) has been recorded using an automatic measurement system (closed chamber method) from 1995–1998. Experiments were laid out to test the impact of water regime, organic amendment, inorganic amendment and rice cultivars. Organic amendments in conjunction with chemical N (urea) effected higher CH4 flux over that of chemical N alone. Application of Sesbania, Azolla and compost resulted in 132, 65 and 68 kg CH4 ha–1 in the wet season of 1996 when pure urea application resulted in 42 kg CH4 ha–1. Intermittent irrigation reduced emissions by 15% as compared to continuous flooding in the dry season of 1996. In the wet season of 1995, four cultivars were tested under rainfed conditions resulting in a range of emissions from 20 to 44 kg CH4 ha–1. Application of nitrification inhibitor dicyandiamide (DCD) inhibited while Nimin stimulated CH4 flux from flooded rice compared to that of urea N alone. Wide variation in CH4 production and oxidation potentials was observed in rice soils tested. Methane oxidation decreased with soil depth, fertilizer-N and nitrification inhibitors while organic amendment stimulated it. The results indicate that CH4 emission from the representative rainfed ecosystem at the experimental site averaged to 32 kg CH4 ha–1 yr–1. 相似文献
6.
Crop Management Affecting Methane Emissions from Irrigated and Rainfed Rice in Central Java (Indonesia) 总被引:4,自引:0,他引:4
P. Setyanto A.K. Makarim A.M. Fagi R. Wassmann L.V. Buendia 《Nutrient Cycling in Agroecosystems》2000,58(1-3):85-93
Methane (CH4) emissions were determined from 1993 to 1998 using an automated closed chamber technique in irrigated and rainfed rice. In Jakenan (Central Java), the two 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 CH4 m–2 d–1, whereas averages in irrigated rice ranged from 71 to 217 mg CH4 m–2 d–1. The impact of organic manure was relatively small in rainfed rice. In the wet season, farmyard manure (FYM) was completely decomposed before CH4 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 CH4 ha–1) and the late-maturing Cisadane had the highest emissions (142 and 116 kg CH4 ha–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. 相似文献
7.
Prabhat K. Gupta C. Sharma Sumana Bhattacharya A.P. Mitra 《Nutrient Cycling in Agroecosystems》2002,64(1-2):19-31
A comprehensive scientific assessment of CH4 budget estimation for Indian rice paddies, based on a decade of measurements in India, is presented. Indian paddy cultivation areas contain soils that have low to medium levels of soil organic carbon. The average seasonally integrated CH4 flux (E
sif) values calculated from these measurements were 15.3 ± 2.6 g m–2 for continuously flooded (CF), 6.9 ± 4.3 g m–2 for intermittently flooded (IF) single aeration (SA) and 2.2 ± 1.5 g m–2 for IF multiple aeration (MA) rice ecosystems. For CF and IF (MA) rice ecosystems having high soil organic carbon, without organic amendments, the CH4 flux (E
sif) may be increased by 1.7 times relative to low soil organic carbon, whereas it may enhance by 5.3 for CF if amended organically. Organic amendment and high soil organic carbon paddy areas do not alter the methane budget estimates for India (3.6±1.4 TgY–1) much, due to their small paddy harvested area. Methane estimated using average emission factors (E
sif) for all paddy water regimes, which include harvested areas having soils with high organic carbon and organic amendments, may give a budget of 5 TgY–1 for India. 相似文献
8.
R.B. Matthews R. Wassmann J.W. Knox L.V. Buendia 《Nutrient Cycling in Agroecosystems》2000,58(1-3):201-217
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 (CH4) 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–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–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 CH4 yr–1) for a province/district were calculated by multiplying the rates of CH4 emission (kg CH4 ha–1 yr–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 CH4 emissions for China, India, Indonesia, Philippines, and Thailand were calculated to be 3.73, 2.14, 1.65, 0.14, and 0.18 Tg CH4 yr–1, respectively. Addition of 3,000 kg DM ha–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 CH4 emissions from these five countries, comprising about 70% of the global rice area, ranged from 6.49 to 17.42 Tg CH4 yr–1, depending on the crop management scenario. 相似文献
9.
Mechanisms of Crop Management Impact on Methane Emissions from Rice Fields in Los Baños, Philippines
R. Wassmann L.V. Buendia R.S. Lantin C.S. Bueno L.A. Lubigan A. Umali N.N. Nocon A.M. Javellana H.U. Neue 《Nutrient Cycling in Agroecosystems》2000,58(1-3):107-119
This article comprises 4 yr of field experiments on methane (CH4) emissions from rice fields conducted at Los Baños, Philippines. The experimental layout allowed automated measurements of CH4 emissions as affected by water regime, soil amendments (mineral and organic), and cultivars. In addition to emission records over 24 h, ebullition and dissolved CH4 in soil solution were recorded in weekly intervals. Emission rates varied in a very wide range from 5 to 634 kg CH4 ha–1, depending on season and crop management. In the 1994 and 1996 experiments, field drying at midtillering reduced CH4 emissions by 15–80% as compared with continuous flooding, without a significant effect on grain yield. The net impact of midtillering 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 CH4 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 CH4 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 CH4 concentrations (from 0 to 20 cm) gave a significant R2 of 0.95 (urea + rice straw), and 0.93 (urea + Sesbania), whereas correlation with dissolved CH4 in the inorganically fertilized soils was inconsistent. A highly significant correlation (R2 =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 CH4 emission potentials under different crop management practices. 相似文献
10.
Methane Emission from Irrigated and Intensively Managed Rice Fields in Central Luzon (Philippines) 总被引:3,自引:0,他引:3
T.M. Corton J.B. Bajita F.S. Grospe R.R. Pamplona C.A. Assis Jr. R. Wassmann R.S. Lantin L. V. Buendia 《Nutrient Cycling in Agroecosystems》2000,58(1-3):37-53
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 m–2 d–1 in the dry season (DS) and 269–503 mg CH4 m–2 d–1 in the wet season (WS). The higher emission 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. 相似文献
11.
R. Wassmann R. S. Lantin H. U. Neue L. V. Buendia T.M. Corton Y. Lu 《Nutrient Cycling in Agroecosystems》2000,58(1-3):23-36
Methane (CH4) 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 CH4 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 CH4 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 CH4 emission by 10–67%. In all rice ecosystems, CH4 emissions can be reduced by 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 (N2O) emissions, changes in water regime are only recommended for rice systems with high baseline emissions of CH4. 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 N2O emissions. 相似文献
12.
N. Sethunathan S. Kumaraswamy A. K. Rath B. Ramakrishnan S. N. Satpathy T. K. Adhya V. R. Rao 《Nutrient Cycling in Agroecosystems》2000,58(1-3):377-388
Experiments were conducted to investigate methane (CH4) production, oxidation, and emission from flooded rice soils. Incorporation of green manure (Sesbania rostrata) into rice fields led to a several-fold increase in CH4 emission. A stimulatory effect of organic sources on CH4 production in soil samples was noticed even under nonflooded conditions. Addition of rice straw at 1% (w/w) to nonflooded soil samples held at –1.5 MPa effected a 230-fold increase in CH4 production over that in corresponding unamended soil samples at 35 d, as compared with a threefold increase in rice straw-amended soil over that in unamended soil under flooded conditions. In a study involving two experimental field sites differing in water regimes but planted to the same rice cultivar (cv Gayatri) and fertilized with prilled urea at 60 kg N ha–1, the field plots with deep submergence of around 30 cm (site I) emitted distinctly more CH4 than did the plots with continuous water depth of 3–6 cm (site II). Likewise, in another incubation study, CH4 production in flooded soil samples increased with a progressive increase in standing water column from 5 mm to 20 mm. Application of carbamate insecticide, carbofuran, at 2 kg ai ha–1 to rice fields retarded CH4 emission through enhanced CH4 oxidation. Hexachlorocyclohexane was found to inhibit CH4 emission. The results suggest the need for extensive research efforts to develop technologies with dual objectives of environmental protection and crop productivity. 相似文献
13.
A field experiment was conducted in a clayey soil to determine the effects of cultural practices on methane (CH4) emissions from rice fields. The factors evaluated were a) direct seeding on dry vs wet soil, b) age of transplanted seedlings (8 d old and 30 d old), and c) fall vs spring plowing. Methane emissions were measured weekly throughout the rice-growing season using a closed static chamber technique. Transplanted 8-d-old seedlings showed the highest emission of 42.4 g CH4 m–2 season–1, followed by transplanted 30-d-seedlings (40.3 g CH4 m–2 season–1), and direct seeding on wet soil (37.1 g CH4 m–2 season–1). Direct seeding on dry soil registered the least emission of 26.9 g CH4 m–2 season–1. Thus transplanting 30-d-old seedlings, direct seeding on wet soil, and direct seeding on dry soil reduced CH4 emission by 5%, 13%, and 37%, respectively, when compared with transplanting 8-d-old seedlings. Methane emission under spring plowing was 42.0 g CH4 m–2 season–1 and that under fall plowing was 31.3 g CH4 m–2 seasons–1. The 26% lower emission in the field plowed in spring was caused by degradation of organic matter over the winter. 相似文献
14.
J.G. Liu Y.H. Zhang K.S. Shao M. Shao L.M. Zeng S.H. Lu S. Slanina H.A.C. Denier van der Gon 《Nutrient Cycling in Agroecosystems》2000,58(1-3):303-310
Two atmospheric diffusion models, the box model ad the ATDL (Atmospheric Turbulent and Diffusion Laboratory) model, were used to calculate regional methane (CH4) emissions of rice fields in the Beijing area. Compared with conventional closed chamber measurements, the box model overestimated CH4 emission because of meteorological conditions--the ground inverse layer was not favorable for the application of the model during the rice-growing season. The ATDL model, on the other hand, handled this unfavorable meteorological condition and gave reasonable CH4 emission estimates (about 6.1–8.5 mg m–2 h–1) close to conventional measurements (about 0.3–14.3 mg m–2 h–1) in June, a period generally characterized by significant CH4 emission from rice fields. In September, CH4 emission as measured with closed chambers was negligible (about 0–0.3 mg m–2 h–1), but the ATDL model still calculated it to be about 2.8–5.3 mg m–2 h–1, albeit at a low level and considerably below the June emission level. This discrepancy cannot be explained at present and needs further stuy. Most likely causes are measurement artifacts and/or the presence of minor local CH4 sources (ditches, field depressions) in the study area. The application of atmospheric diffusion models for regional CH4 emission estimation depends greatly on meteorological conditions. Moreover, the models tend to give much more reliable results during periods of rather high CH4 emission. This coincides with the time that such regional CH4 emission estimates are most valuable. The atmospheric diffusion models complement the closed chamber method by providing integrated CH4 emission estimates from 1–100-km2 rice areas. Detailed information about agricultural management of rice fields and other potential CH4 sources within the study region are necessary to better understand the integrated regional emission estimates. 相似文献
15.
Combining Upscaling and Downscaling of Methane Emissions from Rice Fields: Methodologies and Preliminary Results 总被引:1,自引:0,他引:1
H.A.C. Denier van der Gon P.M. van Bodegom S. Houweling P.H. Verburg N. van Breemen 《Nutrient Cycling in Agroecosystems》2000,58(1-3):285-301
The uncertainty in the methane (CH4) source strength of rice fields is among the highest of all sources in the global CH4 budget. Methods to estimate the source strength of rice fields can be divided into two scaling categories: bottom-up (upscaling) and top-down (downscaling). A brief review of upscaling and downscaling methodologies is presented. The combination of upscaling and downscaling methodologies is proposed as a potential method to reduce the uncertainty in the regional CH4 source strength of rice fields. Some preliminary results based on upscaling and downscaling are presented and the limitations of the approaches are discussed. The first case study focuses on upscaling by using a field-scale model in combination with spatial databases to calculate CH4 emissions for the island of Java. The reliability of upscaling results is limited by the uncertainty in model input parameters such as soil properties and organic carbon management. Because controlling variables such as harvested rice area may change on relatively short time scales, a land use change model (CLUE) was used to quantify the potential land use changes on Java in the period 1994–2010. The predicted changes were evaluated using the CH4 emission model. Temporal scaling by coupling land use change models and emission models is necessary to answer policy-related questions on future greenhouse gas emissions. In a downscaling case study, we investigate if inverse modeling can constrain the emissions from rice fields by testing a standard CH4 from rice scenario and a low CH4 from rice scenario (80 and 30 Tg CH4 yr–1, respectively). The results of this study are not yet conclusive; to obtain fine-resolution CH4 emission estimates over the Southeast Asian continent, the monitoring network atmospheric mixturing ratios need to be extended and located closer to the continental sources. 相似文献
16.
Urease and nitrification inhibitors to reduce emissions of CH4 and N2O in rice production 总被引:2,自引:0,他引:2
Xingkai Xu Pascal Boeckx Oswald Van Cleemput Likai Zhou 《Nutrient Cycling in Agroecosystems》2002,64(1-2):203-211
Strategies used to reduce emissions of N2O and CH4 in rice production normally include irrigation management and fertilization. To date, little information has been published on the measures that can simultaneously reduce both emissions. Effects of application of a urease inhibitor, hydroquinone (HQ), and a nitrification inhibitor, dicyandiamide (DCD) together with urea (U) on N2O and CH4 emission from rice growing were studied in pot experiments. These fertilization treatments were carried out in the presence and absence of wheat straw, applied to the soil surface. Without wheat straw addition, in all treatments with inhibitor(s) the emission of N2O and CH4 was significantly reduced, as compared with the treatment whereby only urea was applied (control). Especially for the U+HQ+DCD treatment, the total emission of N2O and CH4 was about 1/3 and 1/2 of that in the control, respectively. In the presence of wheat straw, the total N2O emission from the U+HQ+DCD treatment was about 1/2 of that from the control. The total CH4 emission was less influenced. Wheat straw addition, however, induced a substantial increase in emissions of N2O and CH4. Hence, simultaneous application of organic materials with a high C/N ratio and N-fertilizer (e.g. urea) is not a suitable method to reduce the N2O and CH4 emission. Application of HQ+DCD together with urea seemed to improve the rice growth and to reduce both emissions. The NO3
–-N content of the rice plants and denitrification of (NO3
–+NO2
–)-N might contribute to the N2O emission from flooded rice fields. 相似文献
17.
R. Wassmann H.U. Neue R.S. Lantin K. Makarim N. Chareonsilp L.V. Buendia H. Rennenberg 《Nutrient Cycling in Agroecosystems》2000,58(1-3):13-22
Methane (CH4) 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. Emission rates accumulated to 52 and 91 kg CH4 ha–1 season–1 corresponding to approximately 40% of emissions from irrigated rice in each season. Distinct drainage periods within the season can drastically reduce CH4 emissions to less than 30 kg CH4 ha–1 season–1 as shown in Los Baños (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 CH4 ha–1 season–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 CH4 emissions. Temporary aeration of flooded rice soils, which is generic in rainfed rice, reduced emission rates due to low CH4 production and high CH4 oxidation. Based on these findings and the global distribution of rice area, irrigated rice accounts globally for 70–80% of CH4 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 CH4 emission without affecting yields. 相似文献
18.
Methane Emission from Deepwater Rice Fields in Thailand 总被引:4,自引:0,他引:4
N. Chareonsilp C. Buddhaboon P. Promnart R. Wassmann R.S. Lantin 《Nutrient Cycling in Agroecosystems》2000,58(1-3):121-130
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–2d–1 and total emission was 98 kg ha–1 yr–1. For irrigated rice, the average emission rate and total emission for the straw ash treatment was 79 mg m–2 d–1 and 74 kg ha–1 yr–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. 相似文献
19.
Xianglan Li Wenping Yuan Hua Xu Zucong Cai Kazuyuki Yagi 《Nutrient Cycling in Agroecosystems》2011,91(3):293-305
Midseason aeration (MSA) of rice paddy fields functions to mitigate CH4 emission by a large margin, while simultaneously promoting N2O emission. Alternation of timing and duration of MSA would affect CH4 and N2O emissions from intermittently irrigated rice paddies. A pot trial and a field experiment were conducted to study the effect
of timing and duration of MSA on CH4 and N2O emissions from irrigated lowland rice paddy soils in China. Four different water regimes, i.e., early aeration, normal aeration
(the same as the local practice in timing and duration of aeration), delayed aeration, and prolonged aeration, were adopted
separately and compared with respect to global warming potential (GWP) of CH4 and N2O emissions and rice yields as well. Total emission of CH4 from the rice fields ranged from 28.6 to 64.1 kg CH4 ha−1, while that of N2O did from 1.71 to 6.30 kg N2O–N ha−1 during the study periods. Compared with the local practice, early aeration reduced CH4 emission by 13.3–16.2% and increased N2O emission by 19.1–68.8%, while delayed aeration reduced N2O emission by 6.8–26.0% and increased CH4 emission by 22.1–47.3%. The lowest GWP of CH4 and N2O emissions occurred in prolonged aeration treatment, however, rice grain yield was reduced by 15.3% in this condition when
compared with normal practice. It was found in the experiments that midseason aeration starting around D 30 after rice transplanting,
just like the local practice, would optimize rice yields while simultaneously limiting GWPs of CH4 and N2O emissions from irrigated lowland rice fields in China. 相似文献
20.
CH4 emission and oxidation in Chinese rice paddies 总被引:1,自引:0,他引:1
In the paper, the characteristics of CH4 emission from the rice paddies, its temporary and spatial variations as well as factors regulating CH4 emission and oxidation are reviewed with an emphasis on CH4 emission from rice paddies in China. The observed four types of diel variation and two type of seasonal variation can be explained by the variations of methane production in the soil and the transport efficiencies of the three transport routs. The inter-annual variation of CH4 emission from rice fields is significant, but the process causing this change is very complicated and unclear based on the available data at present. The large special variation, more than 10 times difference, of the total season methane emissions observed in various rice fields in China, is largely attributed to soil type difference although both soil physics and chemistry are important. Rice growing activities regulate the diel and seasonal variation patterns of the methane emissions. Drainage of flooded water may significantly reduce the emission. Organic fertilizer may enhance the emission, while some of the chemical fertilizers may reduce the emission. Local climate conditions, average temperature and annual rainfall, may be responsible for part of the observed year to year differences of the total season emission. Estimates of total emissions of CH4 from Chinese rice fields, based on field measurement and model calculation, are 9.7–12.7 Tg/year and 8.17–10.52 Tg/year respectively, for the year of 1994. Oxidation of CH4 reduces the emission of CH4 produced in the soil of rice field to the atmosphere. The most likely sites for CH4 oxidation in rice fields are the water–soil interface and the rhizosphere. When the flood water dries up in irrigated fields, the oxidation of CH4 in the soil is more important and can partially explain the lower emission rates during the last period before harvest in most experiments. The magnitude of oxidation in the rhizosphere is not well known. Good correlation between methane reduction and O2 mixing ratio in the soil has been found in most soil types. Methane oxidation rate is mainly controlled by the gas transport resistance in the soil. The oxidation rate increases with the increase of temperature in the temperature range of 5–36 °C. 相似文献