Environmental multifunctionality of Indonesian agriculture

Industrial and urban developments in Indonesia focus on the economic merits, but neglect agricultural services that, when disappear, will destabilize the environmental and livelihood systems. A series of 5-year study has evaluated various aspects of multifunctionality and implications of paddy field conversion on the disappearance of multifunctionality. Soil loss from a series of 18 terraced paddy fields in central Java is negligible. Only a few terraces located along the streams directly caused sedimentation. The functions of flood mitigation, water-resource conservation, erosion reduction, organic waste disposal, heat mitigation, and rural amenity of paddy fields in Citarum watershed in West Java were significant. The ‘replacement costs’ of such functions was about 51% ($92.67 million yr⁻¹) of the total price of rice of $181.34 million yr⁻¹ produced in the 156,000 ha paddy field. This amount could be considered as free services by the farmers to the society. However, because of society's negligence and unawareness, conversion has been accelerating while development of new paddy fields has been decelerating in the last few years. Low and fluctuating price of agricultural products, unavailability or non-affordability of agricultural supplies and inaccessibility to market are among the major disincentives faced by farmers. Because of appreciable multifunctionality they produce, farmers deserve various incentives for the sake of environmental sustainability and other services.     

Carbon and Nitrogen Footprints of Major Cereal Crop Production in China: A Study Based on Farm Management Surveys

Greenhouse gas (GHG) emissions and reactive nitrogen (Nr) releases are central environmental problems, which are closely linked to climate change, environmental ecology and crop production. Sustainable development of agriculture plays an important role in GHG emissions and Nr loss. The life cycle assessment (LCA) method was used to calculate the product and farm carbon footprints (CFs) and nitrogen footprints (NFs) in rice, wheat and maize production in China based on farm survey data. The results pinpointed that the CFs of rice, wheat and maize were 0.87, 0.30 and 0.24 kg/kg. Meanwhile, the computed NFs were 17.11, 14.26 and 6.83 g/kg, respectively. Synthetic nitrogen fertilizer applications and methane (CH₄) emissions were dominant CF sources, while ammonia (NH₃) volatilization was the main NF contributor. Moreover, significant decreases in CF and NF by 20%–54% and 33%–61%, respectively, were found in large-size farms (> 20 hm²) when compared to small-size farms (< 0.7 hm²). Furthermore, the significantly positive relationships between CF and NF indicated the potential for simultaneous mitigation in the regions with high agricultural inputs, like amounts of fertilizer. Based on our results, some effective solutions would be favorable toward mitigating climate change and eutrophication of the major cereal crop production in China, especially optimizing fertilizer use and farm machinery operation efficiencies, as well as developing large-size farms with intensive farming.     

Rice husk biochar application to paddy soil and its effects on soil physical properties,plant growth,and methane emission

The objective of this study was to investigate the effects of the application of rice husk biochar on selected soil physical properties, rice growth, including root extension, and methane (CH₄) emissions from paddy field soil. Three replication experiments were conducted using outdoor pot experiments utilizing commercial rice husk biochar mixed with paddy soil at a rate of 0 (control), 2, and 4 % (weight biochar/weight soil) in which the rice was cultivated for 100 days under a continuously flooded condition. The physical properties of soils were analyzed before and after the growing periods. Some parameters of rice growth and CH₄ emissions of paddy soils were monitored weekly during the experiment. Root extension was also analyzed after harvesting. The experiments showed that the application of rice husk biochar improved the physical properties of paddy soils. It led to a decrease in bulk density and an increase in saturated hydraulic conductivity, including the total pore volume as well as the available soil water content. The shoot height of rice plants was significantly higher in soil amended with 4 % biochar than that in the control soil. However, other plant growth parameters and root extension were only slightly affected by the application. It was also found that amending soil with biochar led to a reduction of the total CH₄ emissions by 45.2 and 54.9 % for an application rate of 2 and 4 %, respectively, compared with the control. Our results showed that the higher the application rate, the stronger the effect of biochar was observed. More research is still necessary for a better understanding of the underlying mechanisms.     

Effects of trees planted on levees on rice yields in rain-fed paddy fields of northeast Thailand

Trees are increasingly being planted on the levees of paddy fields of rice (Oryza sativa L.) in northeast Thailand. We investigated and compared the yields of rice grown in rain-fed paddies under and far from canopies of three different tree species: eucalyptus (Eucalyptus spp.), mango (Mangifera indica L.), and the indigenous neem tree (Azadirachta indica A. Juss). Rice yields tended to decrease near trees of all types at five sites, but there was no change in yields at the remaining 11 sites during the 3-year study. The reduced yields likely resulted from lower aboveground biomass, leading to fewer rice panicles and spikelets, particularly near trees with a dense canopy. Extremely low yields were observed near eucalyptus in paddy fields suffering from severe drought. These results, as well as information provided by farmers’, suggest that eucalyptus trees may have detrimental effects on rice and should not be planted on the levees of paddy fields with relatively low productivity.     

Tracing the fate of nitrogen with <Superscript>15</Superscript>N isotope considering suitable fertilizer rate related to yield and environment impacts in paddy field

While the application rate of nitrogen fertilizer is believed to dramatically influence rice fields and improve the soil conditions in paddy fields, fertilization with low use efficiency and nitrogen loss may cause environmental pollution. In this paper, ¹⁵N-labeled urea was used to trace the fate of nitrogen at four rates (0, 75, 225 and 375 kg N/ha) of urea fertilizer over three split applications in Hangzhou, Zhejiang, in 2014. Plant biomass, the soil nitrogen content of different layers, NH₃ volatilization and N₂O emissions were determined using the ¹⁵N abundance to calculate the portion from nitrogen fertilizer. The results indicated that rice yields increased with the application rate of nitrogen fertilizer. NH₃ volatilization is the main nitrogen loss pathway, and N₂O emissions were significantly associated with nitrogen application rates in the paddy. The percent of nitrogen loss by NH₃ volatilization and N₂O emissions increased with the nitrogen application rate. This study showed that the suitable N fertilizer in a loam clay paddy, considering the yield requirements and environmental issues, is approximately 225 kg N/ha in Hangzhou, with a distribution of 50.06% of the residual in the rice and soil and 48.77% loss as NH₃ volatilization and N₂O emissions. The nitrate from fertilization mainly remained in the 0–20 cm level of the topsoil.     

Wise use of paddy rice fields to partially compensate for the loss of natural wetlands

This paper reviews the scientific information related to climate change impacts on wetlands and functions of human-made wetlands such as paddy rice field and treatment wetland are described to partially compensate for the loss of natural wetlands. Wetlands are among the world’s most productive environments and are cradles of biological diversity, providing the water and primary productivity upon which countless species of plants and animals depend for survival. Considerable evidence suggests that some global warming is occurring, which has important implications for wetland system as well as human life and wildlife. Direct effects of climate change on wetlands are likely to be accentuated by human induced changes that will increase stress to wetland ecosystems. The Ramsar Classification System for Wetland Type provides three broad categories: marine/coastal wetlands, inland wetlands, and human-made wetlands. Human-made wetlands are as important as natural wetlands, and the largest human-made wetland is a paddy rice field (130,000,000 ha) taking about 18% of total global wetland, which is second only to natural fresh wetlands. Paddy rice fields provide not only rice production for food, but also diverse multi-functionalities such as flood control, groundwater recharge, soil erosion control, water quality purification, air purification and cooling, wildlife habitat, amenity and social benefits. The economic value of multi-functionalities estimated by contingent valuation method (CVM) and travel cost method was in the range of U$ 9.75–11.46 billion, which is greater than the value of rice production itself in Korea. Unfortunately, there is an indication of decreased area in paddy rice field in Korea after 1990 showing about 20% decrease in 15 years. Another human-made wetland type is a constructed wetland for water purification, and thousands hectares of wetlands are scheduled to be constructed for reservoir water quality improvement in next 5 years in Korea, and their application is expected to be more common in near future. There is a growing consensus that wetlands are critically important ecosystems that provide globally significant social, economic and environmental benefits. Wise use of human-made wetlands is as important as conservation of natural wetlands, which can be a viable element to overall climate change mitigation and can partially compensate for the loss of natural wetlands.     

Changes in Grain Yield of Rice and Emission of Greenhouse Gases from Paddy Fields after Application of Organic Fertilizers Made from Maize Straw

A field experiment was conducted at the farm of Yangzhou University, Yangzhou, China, to study the effects of organic fertilizers made from maize straw on rice grain yield and the emission of greenhouse gases. Four organic fertilizer treatments were as follows： maize straw （MS）, compost made from maize straw （MC）, methane-generating maize residue （MR）, and black carbon made from maize straw （BC）. These organic fertilizers were applied separately to paddy fields before rice transplanting. No organic fertilizer was applied to the control （CK）. The effects of each organic fertilizer on rice grain yield and emission of greenhouse gases were investigated under two conditions, namely, no nitrogen （N） application （ON） and site-specific N management （SSNM）. Rice grain yields were significantly higher in the MS, MC and MR treatments than those in CK under either ON or SSNM. The MS treatment resulted in the highest grain yield and agronomic N use efficiency. However, no significant difference was observed for these parameters between the BC treatment and CK. The changes in the emissions of methane （CH4） carbon dioxide （CO2）, or nitrous oxide （N20） from the fields were similar among all organic fertilizer treatments during the entire rice growing season. The application of each organic fertilizer significantly increased the emission of each greenhouse gas （except N20 emission in the BC treatment） and global warming potential （GWP）. Emissions of all the greenhouse gases and GWP increased under the same organic fertilizer treatment in the presence of N fertilizer, whereas GWP per unit grain yield decreased. The results indicate that the application of organic fertilizer （MS, MC or MR） could increase grain yield, but also could enhance the emissions of greenhouse gases from paddy fields. High grain yield and environmental efficiency could be achieved by applying SSNM with MR.     

Multidisciplinary assessment of agricultural innovation and its impact: a case study of lowland rice variety WITA 9 in Côte d’Ivoire

ABSTRACT

Information on comprehensive evaluation of agricultural innovations is often limited. This study provides an overview of multidisciplinary evaluation of a lowland rice variety, WITA 9 (released in Côte d’Ivoire in 1998), with respect to its agronomic performance, grain quality, resistance to diseases, adoption by farmers, impact on productivity and farmers’ income, and marketability. WITA 9 had the highest paddy yield among the tested varieties including an international check (IR 64) and recently developed varieties adapted to this country. WITA 9 had a higher amylose content (26–28%) than others tested. This study confirmed its resistance to bacterial leaf blight, Rice yellow mottle virus (RYMV), and rice blast. A household survey showed that the adoption rate was 24%, its paddy yield advantage was 0.7 t ha^–1, and its adoption increased farmer’s income by US$ 91 ha^–1 per season. A market study showed that consumers’ willingness to pay was higher for WITA 9 than any other locally produced rice variety and comparable to imported rice in one of two markets. We conclude that WITA 9 is an ideal innovation for enhancing productivity and rice import substitution in Côte d’Ivoire. An effective seed delivery system and enhancing farmers’ and consumers’ awareness of this variety are vital for accelerating impact.     

Emissions of CH4 and CO2 from paddy fields as affected by tillage practices and crop residues in central China

A field experiment was conducted to investigate effects of tillage practices [no-tillage (NT) and conventional intensive tillage (CT)] and oilseed rape residue returning levels (0, 3000, 6000, 9000 kg dry matter ha^?1) on methane (CH₄) and carbon dioxide (CO₂) emissions and grain yield from paddy fields during the 2011 rice growing season after 2 years oilseed rape-rice rotation in central China. The experiment was established following a split-plot design of a randomized complete block with tillage practices as the main plots and residue returning levels as the sub-plots. NT significantly decreased CO₂ and CH₄ emissions by 38.8 and 27.3 % compared with CT, respectively. Residue returning treatments released significantly more CO₂ and CH₄ by 855.5–10410 and 51.5–210.5 kg ha^?1 than no residue treatments, respectively. The treatments of 3,000 and 6,000 kg ha^?1 residue returning significantly increased rice grain yield by 37.9 and 32.0 % compared with the treatment of no residue returning, respectively. Compared with NT, CT increased yield-scaled emissions of CH₄ and CO₂ by 16.0 %. The treatments of 6,000 and 9,000 kg ha^?1 residue returning significantly increased yield-scaled emissions of CH₄ and CO₂ by 18.1 and 61.5 %, respectively, compared with the treatment of no residue returning. Moreover, the treatment of NT in combination with 3,000 kg ha^?1 residues had the lowest yield-scaled emissions of CH₄ and CO₂ across tillage and residue treatments. In this way, this study revealed that the combination of NT with 3,000 kg ha^?1 residues was a suitable strategy for optimizing carbon emissions and rice grain yield.     

Influence of irrigation frequency on greenhouse gases emission from a paddy soil

Water management is known to be a key factor on methane (CH₄), carbon dioxide (CO₂), and nitrous oxide (N₂O) emissions from paddy soils. A field experiment was conducted to study the effect of continuous irrigation (CI) and intermittent irrigation (II) on these emissions. Methane, CO₂, and N₂O emissions from a paddy soil were sampled weekly using a semi-static closed chamber and quantified with the photoacoustic technique from May to November 2011 in Amposta (Ebro Delta, NE Spain). Intermittent irrigation of rice paddies significantly stimulated (N₂O + N₂)–N emission, whereas no substantial N₂O emission was observed when the soil was re-wetted after the dry phase. The cumulative emission of (N₂O + N₂)–N was significantly larger from the II plots (0.73 kg N₂O–N ha^?1 season^–1, P < 0.05) than from the CI plots (?1.40 kg N₂O–N ha^?1 season^?1). Draining prior to harvesting increased N₂O emissions. Draining and flooding cycles controlled CO₂ emission. The cumulative CO₂ emission from II was 8416.35 kg CO₂ ha^?1 season^?1, significantly larger than that from CI (6045.26 kg CO₂ ha^?1 season^?1, P < 0.05). Lower CH₄ emission due to water drainage increased CO₂ emissions. The soil acted as a sink of CH₄ for both types of irrigation. Neither N₂O–N nor CH₄ emissions were affected by soil temperature. Global warming potential was the highest in II (4738.39 kg CO₂ ha^?1) and the lowest in CI (3463.41 kg CO₂ ha^?1). These findings suggest that CI can significantly mitigate the integrative greenhouse effect caused by CH₄ and N₂O from paddy fields while ensuring the highest rice yield.     

我国水稻安全生产存在的问题及对策探讨

探讨了当前我国水稻安全生产面临的6个方面的主要问题,即气象气候灾害问题、环境污染问题、稻田生物多样性减少与病虫害暴发问题、有害生物入侵问题、转基因水稻生产的安全性问题以及稻米质量安全问题。针对这些问题,提出了一系列的对策措施,即建立稻田环境质量监控体系,加强农田生态环境建设;加强稻田减灾防灾预警体系和抗灾能力建设,发展避灾农业;大力推广与创新应用水稻生态农业模式;以健康食品生产与市场为导向,推进稻米安全生产的标准化与产业化进程;加强对野生稻和水稻优良种质资源的保护与利用;建立有利于水稻安全生产的激励措施和社会监管体系。     

Effect of water management on soil respiration and <Emphasis Type="Italic">NEE</Emphasis> of paddy fields in Southeast China

Water management is an important factor in regulating soil respiration and the net ecosystem exchange of CO₂ (NEE) between croplands and atmosphere. However, how water management affects soil respiration and the NEE of paddy fields remains unexplored. Thus, a 2-year field experiment was carried out to study the effects of controlled irrigation (CI) during the rice season on the variation of soil respiration and NEE, with flooding irrigation (FI) as the control. A decrease of irrigation water input by 46.39% did not significantly affect rice yield but significantly increased irrigation water use efficiency by 0.99 kg m^?3. The soil respiration rate of CI paddy fields was larger than that of FI paddy fields except during the ripening stage. Natural drying management during the ripening stage resulted in a significant increase of the soil respiration rate of the FI paddy fields. Variations of NEE with different water managements were opposite to soil respiration rates during the whole rice growth stages. Total CO₂ emission of CI paddy fields through soil respiration (total R _soil) increased by 11.66% compared with FI paddy fields. The increase of total R _soil resulted in the significant decrease of total net CO₂ absorption of CI paddy fields by 11.57% compared with FI paddy fields (p < 0.05). There were inter-annual differences of soil respiration and the NEE of paddy fields. Frequent alternate wetting and drying processes in the CI paddy fields were the main factors influencing soil respiration and NEE. CI management slightly enhanced the rice dry matter amount but accelerated the consumption and decomposition of soil organic carbon and significantly increased soil respiration, which led to the decrease of net CO₂ absorption. CI management and organic carbon input technologies should be combined in applications to achieve sustainable use of water and soil resources in paddy fields.     

Effect of organic,inorganic and slow-release urea fertilisers on CH<Subscript>4</Subscript> and N<Subscript>2</Subscript>O emissions from rice paddy fields

Vietnam is one of the world’s top two rice exporting countries. However, rice cultivation is the primary source of agriculture’s greenhouse gas (GHG) emissions in Vietnam. In particular, strategies are required to reduce GHG emissions associated with the application of organic and inorganic fertilisers. The objective of this study was to assess the effects of various combinations of biochar (BIOC), compost (COMP) and slow-release urea (SRU) on methane (CH₄) and nitrous oxide (N₂O) emissions. In total, 1170 gas samples were collected from closed gas chambers in rice paddies at Thinh Long commune and Rang Dong farm in northern Vietnam between June and October 2014. The gas samples were analysed for CH₄-C and N₂O-N fluxes using gas chromatography. The application of BIOC alone resulted in the lowest CH₄ emissions (4.8–59 mg C m^?2 h^?1) and lowest N₂O emissions (0.15–0.26 µg N m^?2 h^?1). The combined application of nitrogen–phosphorus–potassium (NPK) + COMP emitted the highest CH₄ (14–72 mg C m^?2 h^?1), while ½NPK + BIOC emitted the highest N₂O (1.03 µg N m^?2 h^?1 in the TL commune), but it was the second lowest (0.495 µg N m^?2 h^?1) in the RD farm. Green urea and orange urea reduced N₂O emissions significantly (p < 0.05) compared to white urea, but no significant differences were observed with respect to CH₄ emissions. SRU fertilisers and BIOC alone measured the lowest greenhouse gas intensity, i.e. <2.5 and 3 kg CO₂ eq. kg^?1 rice grain, respectively. Based on these results, application of fertilisers in the form of BIOC and/or orange or green urea could be a viable option to reduce both CH₄ and N₂O emissions from rice paddy soils.     

Converting rice paddy to dry land farming in the Tai Lake Basin,China: toward an understanding of environmental and economic impacts

Water pollution is a well-known major problem in the Tai Lake Basin, China. Compared to industries and domestic sewage, non-point pollution from agriculture is more difficult to detect, measure, and control. Therefore, a range of policies has been formulated, among which is that of ‘adjustment of the planting structure.’ However, this policy during implementation has been used to simply convert paddy fields to dry land and food crops to cash crops. More surprisingly, to date, no research has provided evidence that such an agricultural land-use change contributes to the reduction of agricultural nutrient pollution. Based on an extensive farm survey, this research finds that conversion of rice paddy to dry land farming has not generated a positive effect on nutrient pollution control. It is estimated that nitrogen runoff from agricultural land has increased by 11 %, while phosphorus runoff has increased more than two times since land-use patterns changed, as farmers are inclined to apply more fertilizer on dry land than in paddy fields. However, this agricultural land-use change is economically effective as land-use conversion increases the net profits of farming in a significant way. It is demonstrated that, compared to environmental concerns, economic considerations are seen to have greater benefits after such an adjustment in the planting structure. These findings have important implications for policy making by local authorities in their efforts to improve environmental management and pollution control in their territories.     

Impact of climate change on paddy field irrigation in southern Taiwan

Climate change can have a serious impact on water resources. The main agricultural product in southern Taiwan is rice, the planting of which consumes far more water than other crops. This makes agriculture in Taiwan especially vulnerable to climate change. In this study, we used the generalized watershed loading functions (GWLF) hydrological model to simulate the discharge of the Kaoping River under climate change scenarios A2 and B2 as released by the Intergovernmental Panel on Climate Change. We discussed the potential impact of climate change on water resources based on the results of GWLF simulations carried out using rainfall and temperature data from five general circulation models (GCMs). The simulation results indicate that river discharge in the wet season increases significantly, and decreases in the dry season. The discharge variations from using the various GCMs as inputs fall within the range of ?26 to +15 % for the dry season and ?10 to +82 % for the wet season. The variation in available water will seriously impact the first period rice farming (the period between the beginning of January and the end of May) in southern Taiwan. Consequently, effective reduction in conveyance loss in the irrigation canal systems and proper fallowing of paddy fields will be the main challenges to Taiwan’s agricultural sector for alleviating the impact of climate change. For further decision making, we show the effects of adapting to climate change by various degrees of the following two methods: fallowing paddy fields to various degrees and reducing conveyance loss in irrigation canal systems.     

Comparative analysis of farmers engaged in participatory research to cope with climate change versus non-participants in Northeast Thailand

ABSTRACT

To assess the extent of improvement of rainfed rice production by using a participatory approach, we compared research project participants and non-participants (total of 206 rice-growing households) with regard to yield variability and their perspective on climate change at seven sites in Northeast Thailand. The participants were characterized by membership in local groups, an active learning attitude, and confidence in their farming. Compared to non-participants, the participants produced crops with higher yield and had more knowledge about the Intergovernmental Panel on Climate Change (IPCC) message and advanced farming technologies. Both groups had similar reactions to past climatic damage experiences, but the participants tended to have a more positive attitude about adaptation to climate change and mitigation by refraining from residual straw burning than the non-participants. The farmers’ attitude about adaptation to climate change was positively associated with their active learning and close relationship with researchers. There was a large yield gap between the bottom 10 percentile farmers (0.63 t/ha) and the top 10 percentile farmers (4.05 t/ha), with an average yield of 2.18 t/ha. Yield was associated with the level of market orientation, with the market-oriented farmers attaining higher yield, including yield from broadcast seeding (2.71 t/ha), than the subsistence farmers (1.66 t/ha). Our findings suggest that technical improvement of rice production in the region by using the participatory approach could be enhanced by selecting participants who are linked with local groups, tend to be market orientated, and are willing to learn with researchers.     

A general adaptation strategy for climate change impacts on paddy cultivation: special reference to the Japanese context

Climate changes due to global warming may affect paddy cultivation considerably. Climate changes directly affect rice plant growth, and within paddy cultivation catchments, alter the hydrological regime including flood patterns and water availability for irrigation, and drainage. Although increased atmospheric CO₂ concentrations in the future may enhance plant growth through the CO₂ fertilization effect, impacts of climate change on agriculture are complicated and difficult to predict precisely. This is especially the case for assessing impacts on paddy cultivation, where basin hydrological behavior needs to be understood in detail. Possible adaptations to reduce negative impacts should be tailored to local conditions, which modify climate change impacts on paddy cultivation. In this article, climate change impacts on paddy cultivation are reviewed and a general adaptation strategy is discussed with special reference to the Japanese context.     

覆膜滴灌条件下稻田CH_4排放研究

为了揭示覆膜滴灌对稻田CH_4综合排放的影响,采用比较分析法分析了覆膜滴管条件下稻田甲烷的排放变化。试验采用覆膜滴灌Ⅰ、覆膜滴灌Ⅱ和漫灌3个处理,分别对当地高产主栽品种吉旱1号进行CH_4排放通量的测定。结果表明,覆膜滴灌稻田CH_4排放通量显著高于漫灌稻田;覆膜滴灌处理条件下,土壤含水率高的覆膜滴灌Ⅰ稻田CH_4排放通量高于覆膜滴灌Ⅱ,说明土壤水分是稻田CH_4排放的主要影响因素之一;3个处理下CH_4的排放趋势大体一致,排放高峰均出现在水稻分蘖的前中期和拔节孕穗期,说明覆膜滴灌未改变稻田CH_4排放的进程。     

Rice-related greenhouse gases in Japan, variations in scale and time and significance for the Kyoto Protocol

The contribution of rice production to the three major greenhouse gases CO₂, CH₄ and N₂O in 1990, the base year of the Kyoto protocol is investigated for Japan. For the CO₂ assessment, we use a top-down life cycle approach, CH₄ is assessed using the Japanese GHG emission inventory and N₂O is assessed according to the ratio of rice area divided by the total area of agricultural soils. In total, 1.6% of greenhouse gas (GHG) emissions in 1990 originated from rice production. Next, we assess regional variations in nine rice-producing regions, based on the CO₂ data of 1990. General trends in rice production from 1960 to 2000 and data from the Japanese GHG emission inventory since 1990 are used to assess variations in time. The rice-related GHG emissions decreased to 1.05% of the total GHG emissions in 2001 and will be less than half the 1990 level in 2012, mainly due to the decrease in rice production. Contrary to the trend in GHG emissions of rice, overall GHG emissions increased as rice production fulfils important roles, in mitigating global warming and in adapting to changing climates. The protection of rice production is required to counter the increase of GHG emissions in transportation, waste and domestic sectors and to minimize problems related to landscape, water and natural hazard management.     

Super Rice Cropping Will Enhance Rice Yield and Reduce CH4 Emission： A Case Study in Nanjing,China

A pot experiment was performed to learn the differences in plant productivity and OH4 emission between two rice cultivars, super rice variety Ningjing 1 and traditional variety Zhendao 11, which were currently commercially appUed in Nanjing, China. Similar seasonal changes of CH4 emission fluxes and soil solution CH4 contents were found between the tested cultivars. Although there was no significant difference in plant biomass production between the cultivars, the grain yield of Ningjing 1 was significantly higher by 35.0% （P 〈 0.05） than that of Zhendao 11, whereas the total CH4 emission from Ningjing 1 was 35.2% lower （P 〈 0.05）. The main difference in the amounts of CH4 emission between the cultivars occurred in the period from the tillering stage to the heading stage. The biomass-scaled and yield-scaled CH4 emissions were respectively 3.8 and 5.2 mg/g for Ningjing 1, significantly lower than those for Zhendao 11 （7.4 and 12.8 mg/g, respectively）. According to the relationships between the plant growth characteristics and the CH4 emission, a stronger root system contributed mainly to the lower CH4 emission of Ningjing 1, as compared with Zhendao 11. Our results demonstrated that super rice has advantages not only in grain productivity but also in CH4 emission mitigation. Further expansion of super rice cropping will enhance rice yield and reduce greenhouse gas emission in China.