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The concentration of methane (CH4), one of the greenhouse gases in the atmosphere is increasing at 1% per annum and rice soil is one of the sources that contribute to about 25% of the atmospheric CH4. This study was conducted with the objectives of (i) assessing CH4 emission from rice fields with various rice management practices in Central Java, Indonesia, (ii) identifying potential mitigation methods by taking into consideration the economic analysis of these methods, and (iii) determining the potential CH4 production and emission from rice soils of Central Java using laboratory incubation method and in-situ field measurements. Field experiments were conducted to investigate the effects of rice cultivars (Memberamo, Cisadane, IR 64 and Way Apo Buru), water management (continuous flooding 5 cm, continuous flooding 1 cm, intermittent irrigation, and pulse irrigation), and crop establishment methods (direct seeding and transplanting) on CH4 emissions using automatic chamber and continuous sampling technique. These experiments were conducted in four seasons beginning in the wet season of 2001/02 and ended in the dry season of 2003. In determining the potential CH4 production and emission from rice field of Central Java, soil types under rice were identified. In-situ measurements of CH4 fluxes from 13 soil types under rice were made and topsoil samples were incubated for laboratory incubation. There were no significant differences between cultivars in yield either through direct seeding or transplanting. Cisadane cultivar established through direct seeding emitted significantly higher amount of CH4 due to higher root and aboveground biomass than transplanting. Since no significant differences in yield between the cultivars were found in this study, Cisadane cultivar should not be used in Central Java. Emission of CH4 could also be reduced by intermittent (46%) and pulse (62%) irrigation compared to conventional continuously flooded systems. Potential CH4 production (28

The concentration of methane (CH4), one of the greenhouse gases in the atmosphere is increasing at 1% per annum and rice soil is one of the sources that contribute to about 25% of the atmospheric CH4. This study was conducted with the objectives of (i) assessing CH4 emission from rice fields with various rice management practices in Central Java, Indonesia, (ii) identifying potential mitigation methods by taking into consideration the economic analysis of these methods, and (iii) determining the potential CH4 production and emission from rice soils of Central Java using laboratory incubation method and in-situ field measurements. Field experiments were conducted to investigate the effects of rice cultivars (Memberamo, Cisadane, IR 64 and Way Apo Buru), water management (continuous flooding 5 cm, continuous flooding 1 cm, intermittent irrigation, and pulse irrigation), and crop establishment methods (direct seeding and transplanting) on CH4 emissions using automatic chamber and continuous sampling technique. These experiments were conducted in four seasons beginning in the wet season of 2001/02 and ended in the dry season of 2003. In determining the potential CH4 production and emission from rice field of Central Java, soil types under rice were identified. In-situ measurements of CH4 fluxes from 13 soil types under rice were made and topsoil samples were incubated for laboratory incubation. There were no significant differences between cultivars in yield either through direct seeding or transplanting. Cisadane cultivar established through direct seeding emitted significantly higher amount of CH4 due to higher root and aboveground biomass than transplanting. Since no significant differences in yield between the cultivars were found in this study, Cisadane cultivar should not be used in Central Java. Emission of CH4 could also be reduced by intermittent (46%) and pulse (62%) irrigation compared to conventional continuously flooded systems. Potential CH4 production (28

This study was conducted with the main objective of studying the emission and production potential of methane (CH4) from different soil types of wetland rice field and determining the controlling soil characteristics affecting methane production. The specific objectives are (i) to determine the best time in the day for manual sampling of CH4 gas in the field, (ii) to measure CH4 fluxes and total emission from three rice fields under field conditions, during the wet and dry seasons, and (iii) to determine the ability of some soils in Java to produce methane from its indigenous and added C source. Two experiments were conducted. The first was a field experiment. Three top soils, classified as brown Regosol, red Latosol and dark brown Alluvial, were placed in a wooden micro-plots lined with plastic sheets and planted with IR 64-rice variety. The soils received continuous irrigation with 5cm ponding above the soil throughout the growing season. A (l m x 1 m x 1 m) plexi-glass chamber was placed on each of the micro-plots to measure daily CH4 flux. The experiment was conducted for two seasons i.e. dry and wet seasons. The Eh and pH changes were recorded regularly every four days. Results of the experiment show that the emission of methane from the soils reached the highest peak at 40 days after transplanting (primordial stage). The emissions declined after they reached the early flowering stage, and drops to the lowest level until the plots were drained. There were no significant differences in grain yield between the three soils from two seasons of observation. Dark brown Alluvial (156. 1 kg CHJha/year) produced the highest emission followed by brown Regosol (142.2 kg CHJha/year) and red Latosol (39.6 kg CHJha/year). Reducing CRt emissions while maintaining or enhancing yield requires information on CRt fluxes from a wide range of ecosystems and climatic zones. An optimal less-intensive sampling strategy with the use of manually operated chamber to measure daily CRt flu

This study was conducted with the main objective of studying the emission and production potential of methane (CH4) from different soil types of wetland rice field and determining the controlling soil characteristics affecting methane production. The specific objectives are (i) to determine the best time in the day for manual sampling of CH4 gas in the field, (ii) to measure CH4 fluxes and total emission from three rice fields under field conditions, during the wet and dry seasons, and (iii) to determine the ability of some soils in Java to produce methane from its indigenous and added C source. Two experiments were conducted. The first was a field experiment. Three top soils, classified as brown Regosol, red Latosol and dark brown Alluvial, were placed in a wooden micro-plots lined with plastic sheets and planted with IR 64-rice variety. The soils received continuous irrigation with 5cm ponding above the soil throughout the growing season. A (l m x 1 m x 1 m) plexi-glass chamber was placed on each of the micro-plots to measure daily CH4 flux. The experiment was conducted for two seasons i.e. dry and wet seasons. The Eh and pH changes were recorded regularly every four days. Results of the experiment show that the emission of methane from the soils reached the highest peak at 40 days after transplanting (primordial stage). The emissions declined after they reached the early flowering stage, and drops to the lowest level until the plots were drained. There were no significant differences in grain yield between the three soils from two seasons of observation. Dark brown Alluvial (156. 1 kg CHJha/year) produced the highest emission followed by brown Regosol (142.2 kg CHJha/year) and red Latosol (39.6 kg CHJha/year). Reducing CRt emissions while maintaining or enhancing yield requires information on CRt fluxes from a wide range of ecosystems and climatic zones. An optimal less-intensive sampling strategy with the use of manually operated chamber to measure daily CRt flu