Soil physicochemical properties in a high-quality tea production area of Thai Nguyen province in northern region,Vietnam

This study investigated general physicochemical properties of tea garden soils at the alluvial plain of Cong River in Tan Cuong commune, Vietnam. Four gardens were selected as study sites on three transect lines established perpendicularly to the river. Soil samples were collected from the surface (0–10 cm) and subsurface (20–30 cm). Soil texture classes varied from sandy loam to light clay, which was affected by different terrains along the transect lines as well as severe disturbance such as terracing and earth excavation. The levels of total C and total N were correlated with increasing garden age, suggesting the replenishment of soil organic matter pool by the addition of plant residue and manure. Meanwhile, the soils showed strongly acidic nature with the average pH(H₂O) of 3.7 at the surface and 3.9 at the subsurface. The effective cation exchange capacity (ECEC) was low at 4.7 and 4.9 cmol_c kg^?1, respectively, and dominated by exchangeable Al³⁺. Soil acidification was exacerbated with increasing garden age. However, a relatively large saturation of exchangeable calcium (Ca²⁺), potassium (K⁺), and magnesium (Mg²⁺) on the ECEC was found in the surface soils. The levels of available P were high, occasionally exceeding 1000 and 500 mg kg^?1 at the surface and subsurface, respectively. In spite of strongly acidic condition, ammonium (NH₄-N) applied as fertilizer was converted to nitrate (NO₃-N) to move down to deeper layers. The levels of the bases, P, and mineral N seem to be principally determined by management practices. Significant portion of these nutrients was likely to exist in water soluble forms without adsorption onto soils. It should be required to develop proper schemes and to educate the owners for adequate fertilizer managements.     

Rural income generation through improving crop-based pig production systems in Vietnam: Diagnostics,interventions, and dissemination

Sweetpotato-pig production is an important system that generates income, utilizes unmarketable crops, and provides manure for soil fertility maintenance. This system is widely practiced from Asia to Africa, with many local variations. Within this system, pigs are generally fed a low nutrient-dense diet, yielding low growth rates and low economic efficiency. Our project in Vietnam went through a process of situation analysis, participatory technology development (PTD), and scaling up over a seven-year period to improve sweetpotato-pig production and to disseminate developed technologies. The situation analysis included a series of pig production assessments in several provinces in northern and southern Vietnam, and pig supply-market chain identification was conducted in 13 provinces. The analysis of these studies informed the project of the following: (1) appropriate locations for our activities; (2) seasonal available feedstuff and farmers feeding practices; (3) market fluctuation and requirements; and (4) feeding and management improvement needs based on which the subsequent phase of PTD was designed. The PTD involved a limited number of farmers participating in sweetpotato varietal selection, sweetpotato root and vine silage processing, seasonal feeding combination, and pig feeding with balanced crop-feed diet and silage. Six years of multi-location and multi-season sweetpotato selection resulted in a few promising varieties that yielded up to 75% more dry matter and have since been formally released. The most significant results of silage processing and feeding trials include improved growth, higher feeding efficiency, increased year-round local feedstuff, and considerable labor reduction from eliminated cooking and vine cutting. Once these technologies were developed, a farmer-to-farmer training model was designed for scaling up the adoption and impact. Farmer trainers from seven communes in seven provinces received training in these technologies. In turn, they undertook the responsibility of training other farmers on sweetpotato selection, processing, and feeding. An impact study was also administered to monitor and evaluate (M&E) the dissemination process and to document the impact of the new technologies and farmer-to-farmer training model on pig growth and farmer income generation. The results showed that both participating and non-participating farmers have taken up the technologies, although the former demonstrates higher rates of adoption than the latter. The participants also generated more income and saved more labor from the adoption of the technologies. While the scaling up and M&E activities are on-going, the project has since broadened from a sweetpotato-pig system perspective to a pig-cropfeed system perspective based on farmers needs. It has included other crop feeds such as cassava and peanut stems in the research portfolio. New technologies based on on-going PTD will continuously be incorporated into the future training curriculum.Dai Peters is currently a senior scientist with the International Center for Tropical Agriculture (CIAT) based in Hanoi, Vietnam. This publication is based on research conducted while she was a research scientist with the International Potato Center (CIP). She holds a PhD from North Carolina State University. Her research interests include on-farm participatory research methodologies, agroenterprise development, and sweetpotato-pig farming systems in Vietnam and Papua, Indonesia. Her recent publications include a manual on crop-based pig feed systems, post-harvest fermentation of sweetpotato roots and vines, and agroenterprise development.Nguyen Thi Tinh is currently a coordinator of the sweetpotato-pig improvement project at the International Potato Center in Vietnam. Ms. Tinh holds a Masters degree in animal nutrition from Wageningen University, Netherlands. She participated in the project on pig feeding trials for five years.Mai Thach Hoanh is a sweetpotato breeder with the Root Crop Research Center of Vietnam Agricultural Science Institute (VASI). He holds a PhD in sweetpotato breeding from the same institute. He participated in the project for seven years on sweetpotato selection. Nguyen The Yen is a crop scientist in the Food Crop Research Institute of Vietnam. He holds a PhD in sweetpotato breeding from VASI. He participated in the project for five years on sweetpotato selection.Pham Ngoc Thach is a lecturer with the Hanoi Agricultural University. He holds a PhD in veterinarian science from the same university. He participated in the project for five years in controlling pig diseases during the feeding trials.Keith Fuglie is a regional coordinator and research scientist in the International Potato Center based at Bogor, Indonesia. He holds a PhD in agriculture economics from the University of Wisconsin. He designed the impact study for the project.     

Effect of sucrose on antioxidant activities and other health-related micronutrients in gamma-aminobutyric acid (GABA)-enriched sprouting Southern Vietnam brown rice

Improving the nutritional quality of germinated brown rice (GBR) is important for the population consuming rice as part of the daily diet to offer health benefits. In this study, a set of popularly grown 79 rice varieties in Southern Vietnam was evaluated to identify the potential materials for producing gamma-aminobutyric acid (GABA)-enriched GBR. Enhancing antioxidant components, antioxidant activities, and other health-promoting micronutrients by sucrose treatment were also investigated in both white and red GBR. The results indicated that OM457 (white rice) and TN11 (red rice)-derived GBR had the highest GABA content of 105.68 mg GABA/100 g F.W and 47.68 mg GABA/100 g F.W among investigated rice varieties, respectively. Sucrose at 50 mM, in general, boosted total phenolic compounds, total flavonoids, anthocyanin content, thereby increasing antioxidant activities in both these GBR. Moreover, GC-MS-based metabolomic analysis indicated that GABA accumulation under sucrose treatment was rice pericarp/variety-specific. Also, sucrose stimulated the accumulation of other health-benefiting metabolites and free sugars. Altogether, the results in this study indicate that sucrose is an effective elicitor for improving the nutritional value in GBR, facilitating for production of ready-to-eat GBR with health-promoting benefits.     

Annual Variations in <Emphasis Type="Italic">Leptospira</Emphasis> Seroprevalence among Sows in Southern Vietnam

A serological survey was conducted among sows in the Mekong delta in southern Vietnam in 1999 to investigate variations in leptospiral Seroprevalence over a one-year period. In this region, leptospirosis is endemic and a high leptospiral Seroprevalence has been shown in the pig population. In this study, the serology of six Leptospira serovars was analysed by the microscopic agglutination test for 429 sows at five large-scale state farms sampled during the dry period, the rainy period and the early dry period. The serovars included were L. interrogans serovar (sv) autumnalis strain Akiyama A, L. interrogans sv bratislava strain Jez, L. interrogans sv icterohaemorrhagiae strain Kantorowicz, L. interrogans sv pomona strain Pomona, L. borgpetersenii sv tarassovi strain Perepelitsin, and L. kirschneri sv grippotyphosa strain Duyster. Variations in Seroprevalence over the year were found for sv bratislava and sv icterohaemorrhagiae: the Seroprevalence was higher during the dry period compared with the rainy period (p = 0.07 and p = 0.005, respectively) and the early dry period (p = 0.00006 and p = 0.0006, respectively). It is concluded that in regions where water is constantly abundant and where animals are exposed to the outdoor environment all year round there are highly significant variations in leptospiral Seroprevalence over the year.     

Mapping ethnic groups in Lao Cai Province,Vietnam

This research note offers a brief summary of recent cartographic work in the province of Lao Cai in northern Vietnam, with a specific focus on the districts of Sa Pa and Bac Ha. By providing a representation of topography in digital format, which enables a connection between demographic and physical variables, the long term aim is to illustrate the relationship between ethnicity and topography.     

Knowledge of Rabies Prevention in Vietnamese Public Health and Animal Health Workers

Rabies is an invariably fatal, but preventable zoonotic disease. Despite a national programme for its prevention and control, the number of rabies associated deaths in Vietnam has increased in recent years. A cross‐sectional survey was undertaken in 2012 to assess and compare the knowledge, awareness and practices of 189 public health workers (PHW) and animal health workers (AHW) attending a joint training course for professionals from provinces in northern Vietnam with the highest number of deaths from rabies. Questionnaires facilitating self‐evaluation were provided, and total knowledge scores were calculated (maximum 38 points) and categorized into: ‘high’ (>30 points), ‘moderate’ (21–30) and ‘low’ (<21). The response rate was 100%, and among the 189 participants, 56% were PHW compared to 44% who were AHW. Although most respondents knew rabies could be transmitted through the bite of an animal, most commonly a dog, and that rabies is a preventable disease, significant differences between groups were identified. Major areas included poor knowledge of common rabies reservoirs, wound management and guidance on post‐exposure prophylaxis. Overall, the total mean knowledge scores for PHW was significantly higher (P = 0.011) compared to those for AHW, but both scores fell within the ‘moderate’ knowledge range. However, proportionately more PHW than AHW achieved ‘high’ knowledge scores (P = 0.0098). To our knowledge this is the first published study to simultaneously assess the knowledge and awareness of animal health and public health professionals attending joint training activities aimed at strengthening rabies prevention and control. To ensure effective prevention and control of rabies requires that AHW and PHW not only coordinate and collaborate, but have a common knowledge and understanding of rabies prevention and control measures. This study provides important baseline data in a relatively unexplored area of research that can focus future interventions and research.     

越南单瓣茉莉与泰国单瓣茉莉的形态性状比较

对越南单瓣茉莉与泰国单瓣茉莉的形态性状进行比较,结果表明:越南单瓣茉莉和泰国单瓣茉莉株高80~100 cm,树姿开张,分枝较稀;越南单瓣茉莉叶长4.2~7.8 cm,叶宽3.0~5.3 cm,花冠直径2.9~3.8 cm,花瓣数8~10枚,伏花百花重27~29 g;泰国单瓣茉莉叶长4.5~7.8 cm,叶宽2.7~4.8 cm,花冠直径2.8~3.3 cm,花瓣数8~12枚,伏花百花重25~27 g。     

Resettlement and the environment in Vietnam: Implications for climate change adaptation planning

Increasingly the environment, and climate risks in particular, are influencing migration and planned resettlement in Vietnam, raising the spectre of increased displacement in a country already confronting serious challenges around sustainable land and water use as well as urbanisation. Planned resettlement has emerged as part of a suite of measures being pursued as part of disaster risk reduction and climate change adaptation strategies. This paper provides an historical, political, legal and environmental overview of resettlement in Vietnam identifying key challenges for framing resettlement as climate change adaptation. The paper outlines the scale of past resettlement in Vietnam, identifying the drivers and implications for vulnerability. Detailed case studies of resettlement are reviewed. Through this review, the paper reflects on the growing threat of climate change and the likelihood of increased displacement associated with worsening climate risks to identify some critical considerations for planned resettlement in climate change adaptation planning.     

Zinc Sorption in Sandy Soils from Central Vietnam as a Function of Soil Characteristics

Zinc (Zn) sorption curves were established for 11 cultivated sandy soils from central Vietnam. Soil samples (10 g) were equilibrated with 5 mM calcium chloride (CaCl₂) solutions (50 mL) at five zinc chloride (ZnCl₂) concentrations (0 to 80 mg Zn L^–1). The experimental sorption data were fitted with the Freundlich equation. The amounts of Zn sorbed by soil (Q_Zn) at different Zn concentrations in the equilibrium solution (C_Zn) were closely related to cation exchange capacity (CEC) and pH, that is, to the available exchange sites at given pH values. More specifically, an excellent correlation was found between Zn sorption and exchangeable calcium (Ca_ex), which evidently also depends on CEC and pH. A unique equation was proposed to predict Q_Zn from C_Zn and Ca_ex in the range of Zn loading covered in our research, that is, from traces to Q_Zn ≈ 60 mg Zn kg^–1.