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This paper studies the determinants of foreign investors’ home bias in the Vietnamese stock market. The research used a database on foreign ownership and the characteristics of 4698 enterprises listed on the Ho Chi Minh Stock Exchange (HOSE) and Hanoi Stock Exchange (HNX) over a 10-year period. A multivariate regression model was constructed using two methods: (i) cross-sectional regressions by year, and (ii) panel data regressions to evaluate the relationship between firm characteristics representing barriers to foreign portfolio investment (FPI) and foreign investors’ home bias in the Vietnamese stock market. The results revealed the impact of firm characteristics representing FPI barriers on the home bias of foreign investors in the Vietnamese stock market – i.e., which business characteristics are preferred by foreign investors when choosing investment portfolios – as well as the impact of FPI barriers on the portfolio selection of foreign investors on the Vietnamese stock market. The research results can be used to identify why foreign investors prefer certain firms in their investment portfolios in order to enhance the attraction of FPI capital, for which the most radical solution is to solve the problem of the investment barriers hidden behind firm characteristics.

This study aims to develop a method for calculating the carbon footprint of rice during its life cycle by combining Life Cycle Assessment (LCA) and the 2006 Guideline of the Intergovernmental Panel on Climate Change (IPCC) for National Greenhouse Gas Inventories (GL 2006) for paddy rice grown in Phu Luong commune, Dong Hung district, Thai Binh province, Vietnam. In the course of the study, a LCA survey that included activities in the upstream processes, the agricultural process, and the post-farm stage was conducted based on interviews with three groups of 30 farmer households that apply the conventional practice of rice production, the system of rice intensification (SRI), or the wide-narrow row method. These cultivation practices are applied for both the winter-spring crop and summer-autumn crop seasons. The emissions were calculated by multiplying the activity data by the default emission factors in GL 2006 or in other relevant studies. The emission factors of methane (CH4) from rice cultivation and nitrous oxide (N2O) from agricultural soil were adjusted using actual measurement results from the Institute of Agricultural Environment (IAE) in 2016. The results of the calculations show that the main sources of the emissions that constitute the carbon footprint of rice include: (i) CH4 emissions from rice cultivation; (ii) electricity generation for irrigation; (iii) diesel combustion for the operation of agricultural machinery, and (iv) fertiliser production. Emissions from other activities were negligible. The carbon footprint of spring rice is 2.69kgCO2e/kg of rice grown using the conventional paddy cultivation method, 2.35 kgCO2e/kg for rice grown using the SRI method, and 2.29 kgCO2e/kg for rice grown using the wide-narrow row method. In summer, the carbon footprint for rice grown using the conventional method is 3.72kgCO2e/kg of rice, 3.56 kgCO2e/kg of rice using SRI, and 3.3kgCO2e/kg of rice using the wide-narrow row method. Three mitigation options are proposed: integrated crop management for rice; alternate wetting and drying; and the substitution of urea fertiliser (CO(NH2)2) with ammonium sulphate ((NH4)2SO4).

Water drainage is an important mitigation option for reducing CH4 (methane) emissions from residue-amended paddy soils. Several studies have indicated a long-term reduction in CH4 emissions, even after re-flooding, suggesting that the mechanism goes beyond creating temporary oxidized conditions in the soil. In this pot trial, the effects of different drainage patterns on straw-derived CH4 and CO2 (carbon dioxide) emissions were compared to identify the balance between straw-carbon CH4 and CO2 emissions influenced by soil aeration over different periods, including effects of drainage on emissions during re-flooding. The water treatments included were: continuous flooding [C] as the control and five drainage patterns (pre-planting drainage [P], early-season drainage [E], midseason drainage [M], pre-planting plus midseason drainage [PM], early-season-plus-midseason drainage [EM]). An equal amount of 13C-enriched rice straw was applied to all treatments to identify straw-derived 13C-gas emissions from soil carbon derived emissions. The highest fluxes of CH4 and δ13C-CH4 were recorded from the control treatment in the first week after straw application. The CH4 flux and δ13C-CH4 were reduced the most (0.1–0.8 μg CH4 g−1 soil day−1 and -13 to −34‰) in the pre-planting and pre-planting plus midseason drainage treatments at day one after transplanting. Total and straw-derived CH4 emissions were reduced by 69% and 78% in pre-planting drainage and 77% and 87% in pre-planting plus midseason drainage respectively, compared to control. The early-season, midseason, pre-planting plus midseason and early-season-plus-midseason drainage treatments resulted in higher total and straw-derived CO2 emissions compared to the control and pre-planting drainage treatments. The pre-planting and pre-planting plus midseason drainage treatments lowered the global warming potential by 47–53%, and early-season and early-season-plus-midseason drainage treatments reduced it by 24–31% compared to control. By using labelled crop residues, this experiment demonstrates a direct link between early drainage and reduced CH4 emissions from incorporated crop residues, eventually leading to a reduction in total global warming potential. It is suggested that accelerated decomposition of the residues during early season drainage prolonged the reduction in CH4 emissions. Therefore, it is important to introduce the early drainage as an effective measure to mitigate CH4 emissions from crop residues.

Rice production systems are an important source of agricultural greenhouse gas (GHG) emissions. Mitigation techniques, such as alternate wetting and drying, have been developed but have often not taken into consideration the constraints imposed by the practices and preferences of farmers. Since GHG mitigation benefits are not obvious at smallholder farm level, it is essential to design site-specific mitigation technologies with the participation of local stakeholders. The purpose of the present study was to adapt a participatory approach to designing and assessing mitigation practices for the dissemination of climate-friendly rice production systems. To improve the hybridization of scientific and local knowledge, a participatory five-step approach to prototyping was applied: (i) diagnosis based on a literature review and survey of stakeholders, (ii) design of mitigation practices based on laboratory trial and local knowledge (that of farmers, agricultural advisors and regional stakeholders), (iii) testing in growth chambers, (iv) testing in farmers' fields and (v) dissemination and assessment. The study was conducted in An Luong village, Red River Delta, northern Vietnam. In the study area, rice residue burning is restricted and farmers have to incorporate residue into the soil. Current water management practices, i.e. conventional continuous flooding and adopted midseason drainage, are not enough to reduce GHG emissions from added residues. Two new water management practices (pre-planting plus midseason drainage and early plus midseason drainage) were designed in participation with local stakeholders, and subsequently tested in the laboratory and in the field with the participation of local farmers. Future mitigation practices were assessed based on the yield, GHG emissions reduction and feedbacks of local stakeholders. Early plus midseason drainage proved to be an effective and feasible mitigation option for rice production in the area. Here we show that participation of local stakeholders in co-designing process help to identify the feasible GHG mitigation options, further it facilitates smallholder rice farmers to implement mitigation practices in their fields.

Lowland rice is a significant source of anthropogenic greenhouse gas emissions (GHGEs) and the primary source of agricultural emissions for many developing countries in Asia. At the same time, rice soils represent one of the largest global soil organic carbon sinks. Straw management is a key factor in controlling the emissions and mitigation potential of rice primarily by affecting methane (CH4) from anaerobic decomposition and carbon losses from burning. Achieving climate-smart management of rice while also improving yields and farm profits, however, is challenging due to economic-environmental trade-offs. This balance could be met with appropriate site-specific practices. This chapter discusses these straw management practices that affect yield-scaled GHGEs and mitigation options in different rice environments.

Rice straw incorporation is labor-intensive and influences greenhouse gas emissions but can increase soil organic carbon (C) and recycle nutrients. Rice straw contains about 80, 40, and 30% of the potassium (K), nitrogen (N), and phosphorus (P), respectively, taken up by rice and thus its incorporation can reduce the fertilizer requirement of the subsequent crop. However, because of rice straw’s low quality, its decomposition is slow. So, the timing of this operation, in combination with water management, becomes important. Composting rice straw with the addition of farmyard manure can improve quality and nutrient supply. Similarly, biochar from thermal combustion of rice straw for energy production can be added to the soil to improve soil organic C. This chapter highlights the benefits derived from incorporating straw into the soil. Alternative forms of straw that can be used by farmers, depending on local situations, are discussed.

This study used the Denitrification-Decomposition (DNDC) model to calculate greenhouse gas emissions from a paddy rice cultivation in ​​Nam Dinh province. The results show that the total CH4 emission from paddy rice field in Nam Dinh province ranges from 404 to 1146kg/ha/year. Total N2O emissions range from 0.8 to 4.2 kg/ha/year; The total amount of CO2e varies between 10,000 and 30,000 kg CO2e / ha / year. CH4 emissions on typical salinealluvial soils, light mechanics are the highest and lowest on alkaline soils. Alluvium, alkaline soils have the highest N2O emissions and the lowest is the typical saline soils. The study has also mapped CH4, N2O and CO2e emissions for Nam Dinh province. Keywords: DNDC, Green house gas, agricultural sector, Nam Dinh, GIS. References: [1] Bộ Tài nguyên và Môi trường, Báo cáo kỹ thuật kiểm kê quốc gia KNK của Việt Nam năm 2014, NXB Tài Nguyên Môi trường và Bản đồ Việt Nam, 2018.[2] D.L. Giltrap, C.Li, S. Saggar, DNDC: A process-based model of greenhouse gas fluxes from agricultural soils, Agriculture, Ecosystems & Environment,Volume 136 (2010), 292–300. https://doi:10.1016/j.agee.2009.06.014.[3] Viện Thổ nhưỡng Nông hóa, Báo cáo kết quả đề tài: “Nghiên cứu, đánh giá tài nguyên đất sản xuất nông nghiệp phục vụ chuyển đổi cơ cấu cây trồng chính có hiệu quả tại tỉnh Nam Định”, 2017.[4] Trung tâm Khí tượng thủy văn quốc gia – Bộ TN&MT, Số liệu thống kê khí tượng thủy văn các trạm khí tượng Văn Lý, Nam Định, Ninh Bình, Thái Bình năm 2014, 2015.[5] Niên giám thống kê tỉnh Nam Định, 2015.[6] T. Weaver, P. Ramachandran, L. Adriano, Policies for High Quality, Safe, and Sustainable Food Supply in the Greater Mekong Subregion. ADB: Manila. (2019) Chapter 7, 178-204.[7] Mai Văn Trịnh, Sổ tay hướng dẫn đo phát thải khí nhà kính trong canh tác lúa. NXB Nông nghiệp, 2016.

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

The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies., This work was supported through the National Socio-Environmental Synthesis Center (SESYNC) National Science Foundation Award DBI-1052875 for the project “Evidence and Decision-Support Tools for Controlling Agricultural Pests with Conservation Interventions” organized by D.S.K. and R.C.-K

Nitrous oxide (N2O) emisison from paddy soil via the soil nitrification and denitrification processes makes an important contribution to atmospheric greenhouse gas concentrations. The soil N2O emission processes are controlled not only by biological, physical and chemical factors but also by farming practices. In recent years, modeling approach has become popular to predict and estimate greenhouse gas fluxes from field studies. In this study, the DeNitrification–DeComposition (DNDC) model were calibrated and tested by incorporating experimental data with the local climate, soil properties and farming management, for its simulation applicability for the irrigated rice system in Duy Xuyen district, a delta lowland area of Vu Gia-Thu Bon River Basin regions. The revised DNDC was then used to quantitatively estimate N2O emissions from rice fields under a range of three management farming practices (water management, crop residue incorporation and nitrogen fertilizer application rate). Results from the simulations indicated that (1) N2O emissions were significantly affected by water management practices; (2) increases in temperature, total fertilizer N input substantially increased N2O emissions. Finally, five 50-year scenarios were simulated with DNDC to predict their long-term impacts on crop yield and N2O emissions. The modelled results suggested that implementation of manure amendment or crop residue incorporation instead of increased nitrogen fertilizer application rates would more efficiently mitigate N2O emissions from the tested rice-based system. Phát thải nitơ ôxít (N2O) từ canh tác lúa nước (thông qua quá trình nitrat hóa và phản nitrat hóa) đóng góp đáng kể vào tổng lượng khí nhà kính có nguồn gốc từ sản xuất nông nghiệp. Quá trình phát thải N2O là không chỉ phụ thuộc vào các yếu tố sinh-lý-hóa học mà còn phụ thuộc các phương pháp canh tác. Trong những năm gần đây, việc ứng dụng mô hình hóa nhằm tính toán và ước lượng sự phát thải khí nhà kính ngày càng trở lên phổ biến. Trong nghiên cứu này, số liệu quan trắc từ thí nghiệm đồng ruộng và dữ liệu về đất đai, khí hậu, biện pháp canh tác được sử dụng để kiểm nghiệm và phân tích độ nhạy của mô hình DNDC (mô hình sinh địa hóa). Sau đó, mô hình được sử dụng để tính toán lượng N2O phát thải trong canh tác lúa nước dưới các phương thức canh tác khác nhau (về chế độ tưới, mức độ vùi phụ phẩm, bón phân hữu cơ, phân đạm) tại huyện Duy Xuyên, thuộc vùng đồng bằng thấp của lưu vực sông Vu Gia-Thu Bồn. Kết quả kiểm định chỉ ra rằng (1) sự phát thải N2O bị ảnh hưởng đáng kể do sự thay đổi chế độ tưới; (2) nhiệt độ tăng và lượng phân bón N tăng sẽ làm tăng phát thải N2O. Kết quả mô phỏng về tác động lâu dài (trong 50 năm) của các yếu tố đến năng suất cây trồng và phát thải N2O cho thấy: Việc sử dụng phân hữu cơ và phụ phẩm nông nghiệp thay thế cho việc bón phân đạm sẽ giúp giảm phát thải N2O đáng kể., Journal of Vietnamese Environment, Vol 8 No 4 (2016)

Nitrous oxide (N2O) emisison from paddy soil via the soil nitrification and denitrification processes makes an important contribution to atmospheric greenhouse gas concentrations. The soil N2O emission processes are controlled not only by biological, physical and chemical factors but also by farming practices. In recent years, modeling approach has become popular to predict and estimate greenhouse gas fluxes from field studies. In this study, the DeNitrification–DeComposition (DNDC) model were calibrated and tested by incorporating experimental data with the local climate, soil properties and farming management, for its simulation applicability for the irrigated rice system in Duy Xuyen district, a delta lowland area of Vu Gia-Thu Bon River Basin regions. The revised DNDC was then used to quantitatively estimate N2O emissions from rice fields under a range of three management farming practices (water management, crop residue incorporation and nitrogen fertilizer application rate). Results from the simulations indicated that (1) N2O emissions were significantly affected by water management practices; (2) increases in temperature, total fertilizer N input substantially increased N2O emissions. Finally, five 50-year scenarios were simulated with DNDC to predict their long-term impacts on crop yield and N2O emissions. The modelled results suggested that implementation of manure amendment or crop residue incorporation instead of increased nitrogen fertilizer application rates would more efficiently mitigate N2O emissions from the tested rice-based system. Phát thải nitơ ôxít (N2O) từ canh tác lúa nước (thông qua quá trình nitrat hóa và phản nitrat hóa) đóng góp đáng kể vào tổng lượng khí nhà kính có nguồn gốc từ sản xuất nông nghiệp. Quá trình phát thải N2O là không chỉ phụ thuộc vào các yếu tố sinh-lý-hóa học mà còn phụ thuộc các phương pháp canh tác. Trong những năm gần đây, việc ứng dụng mô hình hóa nhằm tính toán và ước lượng sự phát thải khí nhà kính ngày càng trở lên phổ biến. Trong nghiên cứu này, số liệu quan trắc từ thí nghiệm đồng ruộng và dữ liệu về đất đai, khí hậu, biện pháp canh tác được sử dụng để kiểm nghiệm và phân tích độ nhạy của mô hình DNDC (mô hình sinh địa hóa). Sau đó, mô hình được sử dụng để tính toán lượng N2O phát thải trong canh tác lúa nước dưới các phương thức canh tác khác nhau (về chế độ tưới, mức độ vùi phụ phẩm, bón phân hữu cơ, phân đạm) tại huyện Duy Xuyên, thuộc vùng đồng bằng thấp của lưu vực sông Vu Gia-Thu Bồn. Kết quả kiểm định chỉ ra rằng (1) sự phát thải N2O bị ảnh hưởng đáng kể do sự thay đổi chế độ tưới; (2) nhiệt độ tăng và lượng phân bón N tăng sẽ làm tăng phát thải N2O. Kết quả mô phỏng về tác động lâu dài (trong 50 năm) của các yếu tố đến năng suất cây trồng và phát thải N2O cho thấy: Việc sử dụng phân hữu cơ và phụ phẩm nông nghiệp thay thế cho việc bón phân đạm sẽ giúp giảm phát thải N2O đáng kể.

The effect of operating temperature on characteristics of single-walled carbon nanotubes (SWNT) based gas sensor was investigated. SWNT-based sensor was fabricated from SWNT powder (Iljin Nanotech, Korea) by screen-printing method. SWNT powder (30 mg, AP grade) was dispersed into 0.78 gram a-terpineol (Aldrich) by ultrasonic vibration for 1 hour then stirred manually for 1 hour to increase adhesion. From this condensed solution, a thick film of SWNT was printed onto alumina substrates. The film then was sintered at 300oC for 2 hours to remove residual impurities. Upon exposure to some gases such as nitrogen, ammonia or nitric oxide, resistance of the sensor dramatically changes due to gas adsorption. In our experiments, SWNT-based sensor was employed to detect NH3 gas in N2 ambience. After saturated of N2, the sensor exposes to NH3 with various concentrations (from 5 ppm to 100 ppm, diluted by N2 as carrier gas). This sensor exhibits a fast response, high sensitivity but slow recovery at room temperature. By heating at high temperature and increasing the flow-rate of carrier gas, NH3 gas desorbs easily and recovery of the sensor improved. The heating also influenced the characteristics of sensors such as response and reproducibility. Other special changes in electric property of SWNT-based sensor caused by heating are also discussed.

Agricultural production in the face of climate change requires a climate-smart transformation and reorientation at multiple scales. Vietnam is one of the developing countries that is agriculture-based and severely affected by climate change; therefore it is crucial that the agricultural system advances toward this transformation. While climate-smart agriculture has gained a significant attention in global fora, context-specific evidence is still scarce in Vietnam. This study examines climate-smart agriculture potentials in tea production systems in the northern mountainous region of Vietnam. Since the climate-smart agriculture concept is multidimensional, which includes food security and adaptation and mitigation, an interdisciplinary analytical framework is employed in this research to assess the economic and biophysical dimensions. Enterprise budgets and representative farms (i.e., farms or households having one or more activities or enterprises) are developed for tea and alternative crops, as well as livestock production, to analyze the productivity dimension of food security. In evaluating the adaptation potential of tea production, local farmers’ perceptions and experiences of extreme weather events are combined with ERA-Interim data (1989-2013) and household survey data on income levels (reanalysis dataset taken from the European Centre for Medium-Range Weather Forecasts; ERA stands for ECMWF Reanalysis). Greenhouse gas emissions and carbon sequestration potentials are estimated through partial Carbon Footprint Life Cycle Assessment. Results show that tea production systems generate net margins, returns to capital, and family labor higher than the alternatives. Farmers, therefore, have high incentives to switch from other crops to tea production. In the face of climate change, tea has shown a strong biophysical adaptive capacity compared to other crops in the northern mountainous region. Tea production systems have a high capability for carbon storage. Evidence of strong synergies between food security and mitigation and adaptation is demonstrated for tea production systems in the northern mountainous region, and potential tradeoffs were highlighted, where relevant.