This study analyzed financial indicators and value chains of solid waste in Can Tho city. This is one of the first research conducted in the Mekong Delta in order to provide a basis for proposing solutions to manage municipal solid waste more effectively and reduce environmental pollution. Results revealed that purchasing activities are quite profitable for both actors. However, awareness about safety and the level of access to basic health care services is still low. The value chain diagram of scrap collection showed that this activity is quite diverse, depending on price fluctuations. Based on the research results, some policy implications for improving the scrap purchasing chain, raising income for actors, and solutions for solid waste management were proposed including propaganda, access to credit, subsidizing purchased products, and supporting basic medical access would help this channel to develop effectively.

This study aims at estimating urban residents' willingness to pay in the Mekong Delta for the improvement of solid waste management by using Contingent Valuation Method - CVM with both parametric and non-parametric approaches. The study also identified factors influencing the willingness to pay by employing logit model. The results from a random survey of 400 observations from three key cities in the Mekong River Delta indicate that urban residents' willingness to pay level is from 86,000 VND to 110,000 VND/month/household for the non-parametric and parametric approach, respectively. The results also determine the factors influencing the decision to pay for the program, including bid level, households who have already classified waste, urban residents who intend to support the program, and urban residents’ income. This research also shows that the difference between the two approaches is small, thereby increasing the reliability of the research results. Besides, in order to encourage households to participate in the waste classification program, the authorities need to raise awareness and encourage higher-income households to participate in-advance.

This article contributed to the digestive tract morphology and the change of Clark index in the Glossogobius aureus. The study was carried out for 12 months (from January to December 2020) at four locations, including Cai Rang, Can Tho city (CRCT), Long Phu, Soc Trang province (LPST); Hoa Binh, Bac Lieu province (HBBL) and Dam Doi, Ca Mau province (DDCM). All fish individuals caught monthly (742 in total, including 382 males and 360 females) using trawl nets were used to determine the digestive tract characteristics and Clark index of this fish. The results showed that the fish mouth was in upward structure, the jaws had two rows of unevenly arranged teeth, and the length of the intestine was short, showing the Glossogobius aureus belonged to the carnivorous fish group. The Clark index of this fish did not change significantly between gender, maturity group and season, but varied considerably by site. The environment in CRCT and DDCM could be favourable in terms of food sources for this species, as the Clark index at these two sites was higher than that of HBBL and LPST. In addition, the Clark index was also affected by gender ´ site, season ´ site. The findings contributed further understanding to the feeding traits of this fish.

The study aims to assess the accumulation of carbon in the mangrove forest in Ca Mau Cape National Park. Soil samples were collected in 5 layers with an even thickness of 20 cm. The indicators were analyzed such as soil bulk density, pH, electric conductivity and salinity concentration, organic matter and carbon content. Soil bulk density fluctuations decreased with depth and did not differ among layers and among three forest states. The indicator of pH among layers and among three forest states did not differ and fluctuated around the neutral range. The EC tends to increase with depth, and differed among layers and among three forest states. The salt concentration varies unevenly and gradually increased with depth, and there were different among layers and among three forest states. Organic matter was varied unevenly, mostly tending to decrease with depth. The carbon accumulation content decreased with depth and remained mostly constant among layers and among three forest states. Soil bulk density and organic matter are closely related to carbon accumulation content.

This study was conducted to investigate the current status of pesticides application and financial efficiency in durian farming in Cu Lao Dai, Vung Liem district, Vinh Long province using field survey and direct interviewed 40 durian farmers. The main durian variety grown was Ri6, which has a higher economic value at the reverse crop than that in the main crop; however, the average investment cost per hectare in the reverse crop was 1.66 times higher than in the main crop (especially for the use of pesticides). The major pests and diseases that appeared were Durian psyllid, fruit borers, mealybugs, cotton worms, leaf scorchers. The results have also recorded 33 active ingredients used in durian cultivation. In particular, the active ingredients have toxicity from group II (moderately toxic) to group IV (slightly toxic) according to the World Health Organization (WHO) classification. Especially, active ingredients acephate was banned since 2019; meanwhile, chlorpyrifos ethyl and fipronil were banned since February 12 in 2021. The dosage of pesticides used was 1.5-2 times higher than recommended. Furthermore, the durian farmers unsafely treat the bottles and packages of pesticides by burning, burying and storing for sale. All in all, the use of pesticides and treatment of its packages have posed potential risks to the environment and public health.

Study on pyrolytic potential acid sulphate soil to absorb phosphorus in biogas effluents was conducted in the lab. Two experiments were arranged randomly, with 5 repetitions: the first experiment used soil types consist of potential acid sulphate soil pyrolyzed with oxygen and the second experiment used soil types consist of potential acid sulphate soil pyrolyzed without oxygen. The soil weight of each type used included: 0 g, 5 g, 7.5 g, 10 g, 12.5g and 15g. The reaction time in both experiments was 30 min. The results showed that the treatment of 7,5 g soil material of both pyrolytic soils had the highest phosphorus absorbent capacity. However, the phosphorus absorbent capacity of pyrolytic potential acid sulphate soil without oxygen was higher than that with oxygen and they were 98,96% and 86,92%, respectively. The pyrolytic potential acid sulphate soil without oxygen can be used to adsorb phosphorus in the biogas effluents.

The study aims to build a map and assess the drought situation for agricultural production in Ben Tre province in the period 2015 - 2019. The data on weather conditions were collected at the Ben Tre Hydro-meteorological Station; the Inverse Distance Weighted method (IDW) was used to build drought maps; the level of impact of drought is assessed based on the Standardized Precipitation Index (SPI). The study results showed that Ben Tre province has 4 zones of drought levels: heavy, medium, light and non-drought. The situation of heavy drought zone and medium drought zone were expressed the most in the period 2015 - 2016, the other years are light drought. However, the drought area in 2019 accounted for the highest, decrease in the following years 2017, 2016, 2015, 2018. Drought has been impacting of farming system in Ben Tre province. Therefore, it is necessary to have professional assessments on the effects of drought on agricultural production and land in order to have reasonable and sustainable land use orientations.

This study aims at assessing the impact of economic, social and environmental factors which drive the changes of agricultural cropping systems in My Xuyen district, Soc Trang province from 2015 to 2020. Structure interviews with 40 farmers and depth interviews with nine governmental staff were conducted to investigate the impact of the driving factors on the decision making to change the cropping systems. Interview data were processed and analyzed by descriptive statistics, conversion of qualitative into quantitative data, and the Analytic Hierarchy Process. The results reveal three popular changes of cropping systems in My Xuyen. They include changes (1) from rice-based crops to intensive shrimp farming, (2) from rice-based crops to rice-shrimp farming and (3) from rice-shrimp farming to intensive shrimp farming. About 87.81% of farming system changes are influenced by the driven factors which are ranged as (i) profit, (ii) neighbor farming systems, (iii) saline intrusion in surface water, (iv) production cost and (v) weather conditions. These factors contribute to about 87.81% of farmer decisions in changes of agricultural cropping systems.

Long-term cultivation inside the dike area (without flood discharge) will leave many impacts on socio - economic aspects. The objective of the study is to evaluate the current farming situation and financial efficiency of rice cultivation inside and outside the dike in the acid sulfate soil and ancient alluvial soils area of An Giang province. The research was conducted in Luong An Tra commune, Tri Ton district and An Nong commune, Tinh Bien district. In each district, 60 households engaged in agricultural production inside and outside the dike were randomly interviewed. The results showed that the total average production cost per crop for cultivated 3 rice crops/year inside the dike is higher than outside the dike (2 rice crops/year) in both study site Tri Ton and Tinh Bien. In which fertilizer and pesticide costs are highest. The cost of fertilizers and pesticides in triple rice cropping areas (inside dikes) is 1.48 times higher in Tri Ton and 1.15 times in Tinh Bien compared to double rice cropping areas (outside dikes). The average profit for a rice crop in inside the dike is higher than outside the dike is 3.410.822 VND/ha/crop and 2.867.819 VND/ha/crop in Tri Ton and Tinh Bien, respectively.

With the goal of moving towards sustainable agriculture by reducing the use of chemical fertilizers, the contingent valuation model (CVM) was used to assess the demand of fruit growers through estimating their willingness to pay for the proposed organic liquid biomass fertilizer in Cho Lach district, Ben Tre province. The results showed that over 60% of respondents supported and agreed to buy the liquid biomass fertilizer with a willingness to pay or a price around VND 172,000 per ton. Farmers who are older, more highly educated, and have used bio-organic fertilizers in the past, are more interested in and more likely to pay the liquid biomass fertilizer.

This study was conducted with the aim of providing data on aquatic weeds in the paddy rice ecosystem in An Giang province as a scientific basis for more effective weed use, management and control in rice fields. The methods, namely the PRA, field investigation and aquatic weed sampling in 24 quadrats of 12 rice fields, in 6 districts and cities of An Giang province, morphological comparison and classification, statistical analysis, were used in this study. The results showed that a total of 37 species of aquatic weeds belonging to 33 genera, 20 families in 2 divisions were recorded. They were classified into four groups of life forms, of which, groups of energent life and floating leaf are predominant. The number of use-value species was 33 species, dominated by species used as medicine, as vegetables, and as feed for livestock and poultry. The species composition was recorded the highest richness and diversity in the Winter-Spring crop and the Tri Ton district’s fields. Although the species composition was diverse, a few species appeared with high frequency (Group D, E). Most of species were in low frequency (Group A). The highest density of aquatic weeds was in the Summer-Autumn crop (an average of 15.67±0,34 shoots/m2) and Chau Phu district's fields (an average of 25.96±0,45 shoots/m2). The richness and diversity of species composition and density of aquatic weeds in rice fields were less affected by the dike system.

This study was carried out in Phu Xuan and Hiep Xuong commune, Phu Tan district, An Giang province. The study aimed to evaluate characteristics of rice paddy soil quality between inside and outside of the full-dyke systems. Soil samples were collected at (i) 15 sites in the inside area of the full-dyke systems in 02/2018 and 10/2018, and (ii) 15 sites in the outside area of the full-dyke systems in 02/2018 and 8/2018. Soil samples were collected by the combination method with 5 sampling sites (0-20 cm) for analyzing the bulk density, density, porosity, soil texture, pH, EC, soil organic matter (SOM), cation exchange capacity (CEC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), and nitrate (NO3-N). The results showed that pH, density, bulk density, porosity, and soil texture were not significantly different between soil samples inside and outside the full-dyke systems, except EC value. The SOM, CEC, TN, and TP of soil samples inside the full-dyke system were higher than that of outside with the value of SOM (8.67 % and 5.49%), CEC (26.1 cmol kg-1 and 20.7 cmol kg-1), TN (0.32 %N and 0.25 %N), and TP (0.19 %P2O5 and 0.14 %P2O5), respectively. The NO3-N of soils samples were not significant different between inside (1.74 mg kg-1) and outside (1.52 mg kg-1) the full-dyke systems (p>0.05). Similarly, TK (%K2O) were similar between soil samples inside and outside at 1.33 %K2O and 1.32 %K2O, respectively. The result showed that SOM, TN, and TP soil samples inside were higher than that of outside the full-dyke system.

The study aims at identifying carriers to evaluate density and activities of three functional bacterial isolates preserved in four different organic residues carriers and their efficacy after storage on degrading organic household wastes. The density and activities of bacterial strains were investigated during the incubation period. Bacterial inoculants from the efficient storage carriers were mixed each other (w/w) and used to evaluate its efficiency on treating household waste under laboratory conditions. After 6 months of storage, the density of three bacterial strains maintained over 8 log CFU/g in the carriers. In particular, ground coir showed the best carrier for maintaining the density of pTVC3 and cAT1 and rice bran carrier was the best for aCR1, giving density above 7 log CFU/g carriers, respectively. The enzymatic activities of these three strains were also maintained for up to 6-month storage. The organic household waste treated by the mixture of the inoculant treatments decomposed significantly and reached 80% at 3 days after inoculation. The product from the organic household waste had no odor, low density of E. coli, soft and met the regulations on the safety and quality of organic fertilizer.

The study was conducted to determine the salinity tolerance of two black-seeded sesame varieties of ADB1 and double-husk Binh Thuan when watering with saline water at salinity concentrations of 2 and 4‰ and to evaluate the potential for salinity in paddy soils during sesame cultivation watering with saline water. The experiment used briny mixed diluted with river water to have salinity concentrations determined by a refractometer of 2 and 4‰ (0‰ was the control treatment, river water only). The experiment was arranged in a net house, in a completely randomized design with 3 replicates and two factors that of the first factor including unplanted, ADB1 and double-husk Binh Thuan species; and the second factor comprising of 0, 2 and 4‰ salinity levels. The results after 14 days of saline watering (total 2.5 L of salt water/6 kg soil) and continuing irrigation with river water until the end of experment showed that the treatment with salinity concentration of 4‰ having salt accumulated in the soil (ECe>4 mS/cm), considered saline soil. However, due to the short salinisation period of 14 days, watering at salinity concentration of 4‰ did not affect the growth and yields of the two studied sesame varieties including plant height, root length, fresh root biomass, pod number, seed yield and 1000 seed weight.

The study was conducted to evaluate some parameters of surface water quality in the typical farming models in Cu Lao Dung, Soc Trang province, contributing to providing information for local agricultural decisions. The evaluated parameters of surface water quality include pH, dissolved oxygen (DO), temperature (0C), electrical conductivity (EC), salinity, BOD520, total nitrogen and total phosphorus. Water samples were collected at four representative farming models in the surveyed area, namely Shrimp Pond (whiteleg shrimp farming), longan orchard, mango orchard and coconut orchard in the rainy seasons (10/2019) and in the dry season (3/2020). The results indicated the water quality in the surveyed area met the requirement for agricultural irrigation according to QCVN08:2015/BTNMT (column B1). However, the high salinity level (2.8 – 3.3 ppt) in the dry season may affect the growth of fruit trees and the development of orchard models. Besides, it is necessary to control BOD520 in the shrimp farming model in the dry season to limit the negative effects on the water quality when discharged to the surrounding environment.

Changes in using agricultural land pose challenges for land managers in terms of ensuring the implementation of local land-use plans. The paper aims to build a land-use change model for simulating land-use changes under the impacts of socio-economic and environmental factors. The model was built based on Agent-based modeling approach using GAMA software. In which the land-use decision-making process is based on the multi-criteria selection that the main factors were land suitability, land convertibility, land-use situation of neighbors, and profitability of land-use patterns. The input data for simulation were the land-use maps in 2010, 2015 and 2020 of Tran De district, Soc Trang province. A new model was built and has been calibrated using land-use map in 2015 (with Kappa = 0.71). The model has been verified with the land use map in 2020 with the simulation error percentage, nRMSE, which was 5.2%. The simulated results showed that rice land tends to change to rice-vegetable, specialized crops and perennial fruit trees to respond to climate in 2030. The case study showed that the model is an essential tool for helping land managers and farmers to build adaptive land-use plans.

This study aimed to analyze the current situation, people's awareness, and factors affecting the decision to participate in the source-separation program of municipal solid waste in the Mekong Delta. Primary data were collected by directly interviewing 545 households in Can Tho city and An Giang province. The binary Logit model was employed to determine the factors that influence the decision to participate in the program. Research results reveal that there were increases in people's awareness of the benefits of source-separation, the amount of municipal solid waste collected, and the number of households supporting the program. The results of the Logit model confirm the influence of the time factor, the respondents supporting the environmental protection program, income, and the area without the pilot program affecting the decision to participate in the program. Thus, local authorities should pay attention to disseminating program information to all people, especially in urban areas. In addition, in the future, when implementing the program in the rest areas, local authorities need to perform well and under high standards to increase the belief of participating and non-participating households.

The study was conducted for evaluating the economic, social and environmental efficiency of rice cultivation before and after flooding, as the base for suggesting practical solutions of flood management in Tri Ton, An Giang. This research was applied cost-benefit analysis method, Likert scale in data evaluation. The evaluated parameters were based on land assessment criteria from Food and Agriculture Organization (FAO) and other studies previously conducted in the Mekong Delta. Compared to those before flood discharge, flood discharge brings higher values to rice yield (6.4 vs. 5.6 tons/ha), profit (15.8 vs. 11.4 million VND/crop), the amount of fertilizers, pesticides as well as the frequency decreased compared to before flood discharge. The soil environment was improved by flood which provided more alluvium, nutrientand increased aquatic resources. The study results showed that rice cultivation after flood discharge brings economic, social and environmental benefits compared to before flood discharge. The economic, social and environmental score of rice cultivation after flooding was greater than before flooding at 0.96 and 0.86, respectively.

The study was conducted to evaluate the biodiversity of phytoplankton in the full-dyke (FD) and semi-dyke (SD) systems in Vong Dong communes, Thoai Son district, An Giang province. Phytoplankton samples were collected in the dry season (April) and in the rainy season (October) in 2019. Total of 30 sampling sites was selected for collecting the phytoplankton samples. The results identified that the number of phytoplankton species in the FD system (42 species) was lower than that in the SD system (74 species) in the dry season, but in the rainy season, the value in the FD system (113 species) recorded higher than in the SD system (101 species). The Bacillariophyta and Euglenophyta were dominant in the FD system but in the SD system, the Chlorophyta and Euglenophyta were dominat. The density of phytoplankton in the FD system was lower than that the SD system. The average density of phytoplankton in the dry season determined 4.980 individuals/L and 13.943 individuals/L, respectively. Meanwhile, in the rainy season, the mean density of phytoplankton recorded 11.540 individuals/L in the FD systems and 13.550 individuals/L in the SD systems. Shannon-Weiner diversity index (H') ranged from 1.22 to 3.55 in the FD systems and 1.27-3.58 in the SD systems. The water quality in study sites ranged from light to heavy pollution in both seasons. In general, the density and number of phytoplankton species in the FD system were decreased. In long-term, the paddy fields in the FD system will lose an amount of an organic fertilizer source in the future.

The objective of the study was to assess the potential use of plastic straws as carrier in a submerged biological filter for domestic wastewater treatment. Used plastic straws were collected and formed into a cylindrical block media with a length of 2.5 cm and a diameter of 1.8 cm for biofilm growth. Two identical biological filters were designed with an LxWxH dimension of 0.15 m x 0.15 m x 1.2 m. The total medium height (0.7 m) was kept immobile and completely submerged in wastewater with 0.25 m from the bottom and to the open surface of the reactor. Two filters were operated in parallel. The hydraulic retention times (HRT) were 5 h and 6 h for the aerated filter and 6 h and 8 h for the non-aerated filter. Experimental results showed that the effluent concentrations of TSS, BOD5, COD, N-NO3-, TP, P-PO43-of the two biological filters in this study met type A QCVN 14:2008/BTNMT, except for N-NH4+. When the hydraulic retention time increased to 6 hours in the aerated filter, the removal efficiency increased and the N-NH4+ reached type B QCVN 14:2008/BTNMT. The biological filter without aeration had higher N-NO3- removal rate than the aerated filter, but other parameters were in reverse. In short, used plastic straws can be reused to serve as the carrier in the submerged biological filters for domestic wastewater treatment.

The aim of this study was to investigate effects of biochar and water management on some soil chemical and biological parameters as well as rice yields grown on the early winter-spring crop in 2019-2020 at Binh Thuy district, Can Tho city. The field experiment was set up as a randomized complete block (RCB) design with a total of six treatments (n=3) from two factors including biochar kinds/types and water management regimes. Results showed that biochar amendments as well as water management regimes increased soil pH, organic matter content in soil (%C) and decreased EC parameters significantly in comparison to those of the control treatment. Presence of arbuscular mycorrhizal fungal community as well as the density of phosphorus solubilizing bacteria were affected by either biochar amendments or/and water management regimes. The density of the total bacteria, total fungi, free nitrogen-fixing bacteria, cellulolytic bacteria, and rice yield were not affected by these factors in this study.

Mekong Delta is a rapidly urbanized area compared to the average urbanization rate in the whole country, therefore, providing timely information on urban land plays an important role in urban monitoring and management. Remote sensing technology has been proven by many studies to be an effective tool in urban monitoring and management. There are many indices used in remote sensing to classify urban land (NDBI, NBI and IBI), however, each index has both advantages and disadvantages. The objective of this research is to compare the reliability of different indices used for urban land classification using Sentinel-2 data and propose the best index for urban land classification. An object-based approach was used based on NDBI, NBI and IBI indices to classify urban land in Long Xuyen city of An Giang province, Ca Mau city of Ca Mau province and Ninh Kieu district of Can Tho city. The results showed that the urban land classification method based on IBI, NDBI and NBI indices reach the reliability standardized classification in which IBI index provided the highest reliability. Therefore, the IBI index can be used to classify urban area, especially in the Mekong Delta using Sentinel-2 data.

The main purpose of this research is an evaluation of the nitratee removal efficiency from biogas solution by using bamboo biochar. The characteristics of the bamboo biochar were determined by Brunauer-Emmett-Teller (BET) test, and Scanning electron microscopy (SEM). The experiment was conducted in the lab and designed completely randomized with five replications. The results demonstrated that the optimum conditions for the effective adsorption of nitratee ion onto bamboo biochar were found to be pH 4, biochar dosage of 1 g L-1, and retention time of 15 min. The experimental data were fitted to different adsorption isotherms models (Langmuir, Freundlich models). The maximum adsorption capacity of bamboo biochar for nitratee removal was found to be 8.1 mg g−1.

The study aimed at analyzing the leafy vegetable cultivation current status of energy consumption through agricultural inputs and financial efficiency in My Thuan commune, Hon Dat district, Kien Giang province. The study was carried out from January to July 2021. Sixty leaders, or those primarily responsible for the cultivation, having a cultivated area of 1,000 m2 or more were face-to-face interviewed. The MiLCA commercial software version 2.3 was used to analyze energy consumption through the higher heating method based on the types and quantity of agricultural inputs usage. Research results showed that leafy vegetable cultivation benefited financial efficiency in this study was not significantly higher than the typical agricultural cultivation model in Kien Giang province (75.289.000 VND/ha/crop – including the labor costs). Leafy vegetable cultivation used 44,118 MJ/ha/crop and 2.68 MJ/kg of commercial product. These energy consumption values were higher than the value of cultivated lettuce and Chinese kale in Thailand based on growing area, but lower than the value based on commercial leafy vegetable weight. To improve cost and energy efficiency, farmers have to enhance the fertilizer use efficiency through proper schedule fertilization and biochar application.

The study was conducted to determine the actual results of the land use planning of Can Tho city in the period 2010-2020 based on comparing the current state of land use and targets in two land use plan periods (2010-2015 and 2015-2020). Using exploratory factor analysis (EFA) model and multivariable linear regression model to identify the factors affecting land use planning in Can Tho city with 100 land governors. The results indicated that the land use in the period 2010-2020 did not achieve according to the plan. There are 5 groups of factors that positively affect the land use planning in Can Tho city from land governor’s point of view including group of institutional and legal factors, group of social factors, group of economic factors, group of environmental factors and group of other factors. In the coming time, in order to make land use planning in Can Tho city more and more effective, governors need to pay attention to the following: (i) perfecting the provisions of the law on land use planning, (ii) assessing the impact of urbanization speed in forecasting land use demand in the planning process, (iii) training staff to do planning.

Biochar amendment is considered as a method improving and reducing CH4 emission from paddy fields. The study was conducted to evaluate the reduction of CH4 emission when supplement of different biochar into flooded soil in the laboratory condition. The study was a completely randomized design with 7 treatments including rice husk biochar (RB) and bamboo biochar (BB) at 3 ratios of supplemented biochar at 0.1, 0.2 and 0.5% (calculated by weight of biochar and weight of soil) and the control (without biochar). The results showed that CH4 emission rates were highest, at 58.2-87.9 µg/kg/day, during 7-10 days after incubation. Adding rice husk biochar into flooded soil reduces CH4 emissions from 21.9-49.6% and 27.5-42.5% when added 0.2 - 0.5% of rice husk and bamboo biochar, respectively. Amending of rice husk biochar at 0.5% resulted in reducing of 49.64% of total methane emission compared to the control. It is necessary to conduct the field experiment to confirm the reducion of methane emission when applying biochar in the paddy fields.

The field study is am at evaluating the effects of organic matter amendments on soil biological and chemical parameters during the rice plant growth at Tran De district, Soc Trang province. The field experiment was set up as a randomized complete block design with three treatments (NT) (n=3). The results showed that treatments applied by either NT2-Biochar or NT3- chicken maure (PHC) in combination with the inorganic fertilizers increased significantly the densities of the culturable fungi and bacteria as well as nitrogen fixing bacteria, phosphorus solubilizing bacteria, cellulolytic bacteria compared to those of the NT1-inorganic fertilizer regime (KC). In addition, NT2-Biochar increased soil total organic matter, P availability and total phosphorus. The total amount of CH4 gaseous emission from the NT2-Biochar was the least and was significantly different compared to that of the other treatments. However, rice yields did not differ among treatments. The results showed that the application of organic matters together with inorganic fertilizers helped increasing beneficial functional bacterial groups and some soil chemical parametersand biochar amendment mitigated CH4 emission in the rice monoculture system in winter-spring crop of the year 2018-2019.

The study provided knowledge of factors influencing morphological traits of graceful mudskipper (Periophthalmus gracilis), a fish species distributed in the coastal mudflat in the Mekong Delta. Fish specimens were monthly collected in four sites in Mekong Delta, from April 2020 to March 2021. The analysis of 486 individuals showed that fish’s total weight (TW) changed with site and sex, whereas fish’s total length (TL) did not vary with these variables. The interaction of season ´ site had the effect of changing the values ​​of TW. Other morphometrics such as body height (BH), head length (HL), eye distance (ED), eye diameter (DE) did not change by season and sex, but by sites. Besides, meristics such as HL/TL, BH/TL, ED/HL and DE/HL varied by study site and did not change by season and sex. This fish’s morphological parameters and most morphological ratios were not affected by season ´ sex, season ´ site, sex ´ site. This study contributed understanding to the identification and the ecological adaptation of this species.

Marshal 200SC containing carbosulfan 200g/L has been used in rice crop in the Mekong delta. Toxic mechanism of carbosulfan for organisms is cholinesterase (ChE) inhibition. Silver barb (Barbonymus gonionotus) distributes in variety waterbodies and is cultured in integrated rice – fish system in the Mekon g delta. Therefore, this species would be a high risk of exposure to the use of this pesticide. This study aimed to determine the effects of sub-lethal concentrations of this pesticide on ChE activities and growth performance of silver barb. Three sub-lethal concentrations (1, 10 and 20% LC50-96h) of this pesticide were conducted in laboratory condition for assessing effects of Marshall 200SC on ChE in 96h and on the growth of fingerlings in 60 days . Results showed that LC50-96h of Marshal 200SC for this species is 1.375 ppm (equivalent 0.275 mg/L Carbosulfan). Brain ChE of the fish is more sensitive with Marshal 200SC than growth performances. ChE activity was inhibited 18.4% at concentration of 1%LC50-96h. At the concentration of 20%LC50-96h, FCR and FI increased up to 129.6% and 116.7% of control respectively, but SGR decreased to 74,5% of control. Investigate effects of Marshal 200SC for this fish species in field condition needs to be carried out.

The aim of this study was to isolate bacterial strains that are capable of degrading protein and cellulose from different organic domestic waste resources. Effects of isolated bacteria on the survival of earthworms (Perionyx excavates) were also investigated under in vitro study. Seventy five organic waste samples were collected from bazaars, small restaurants and house-hold samples for isolating and screening their functions of protease, cellulase and earthworm survival. The results showed that 58 bacterial strains were isolated from domestic organic wastes. Among them, 46 bacterial isolates released protease activity and 12 bacterial isolates had cellulolytic activity. A quantitative evaluation of these functional bacterial isolates further selected three protein bacterial isolates of pAT3, pPT1, pTVC3 and three cellulolytic isolates of cAT1, cAT1 and cCR1 that had fast degradation of pork and fish meat wastes and vegetable waste samples, respectively. Based on the 16S rRNA sequence, 5 bacterial strains were identified at the species level and one unidentified bacterium. These 6 bacterial strains caused less odour of the organic matter than that of the control treatment and they did not affected on the survival and the growth of earthworms under invitro study.

The study is aimed at monitoring and evaluating the change of rice crops in the dyke-protected areas surrounding Plain of Reeds in the two years 2000 and 2019. LANDSAT data was applied a water index (Normalized Difference Water Index-NDWI) and the shoreline extraction and MODIS data was detected by vegetation index (Normalized Difference Vegetation Index-NDVI) using unsupervised classification (ISODATA algorithm). An accuracy assessment obtained a high significant with overall accuracy and kappa coefficient more than 85 percentage and 0.7, respectively. The results show that rice crop area increased at 126.139,40 ha (19,36%) insite the ring dike areas. There has no single-rice crop cultivation that almost converted into double-rice crop and triple-rice crop in 2019 with the increasing at 81,229.47 ha (39.18%) and 126.142,15 ha (60,82%) comparing to 2000. Land use conversion is mainly distributed in Thap Muoi and Cao Lanh districts in Dong Thap province, Moc Hoa district in Long An province, and Cai Be and Cai Lay districts in Tien Giang province.

The study aims to identify and evaluate the factors that affect the farming patterns in Ben Tre province. The methods of Analytical Hierarchy Process (AHP), Cronbach’s Alpha and Exploratory Factor Analysis were applied to verify the factors, and interview 9 experts to assess the impact of the factors. The results showed that there are 4 main factors and 16 sub-factors. In the main factor, the factor of people was the highest impacting weight, next was policy, economics and the lowest was natural condition. In the sub-factors of natural condition, influenced by salinity was the highest impacting weight and soil influence was the lowest impacting weight. In sub-fators of policy, land use policy was the highest impacting weight and technical support was the lowest impacting weight. In the sub-factors of economics, capital capacity was the highest impacting weight and capital efficiency was the lowest. In the sub-factors of people, education level was the highest impacting weight and labor sources was the lowest. The total assessment showed that factors of education level, technical science, financial support policies and land use policies were the highest impacting weight, while the factors of market, flood and drought were the lowest impacting weight.

In this study, the choice experiment (CE) approach was applied to determine Can Tho city consumer’s preference for the attributes of the eco-label Chinese cabbage. The results showed that respondents were willing to pay about 15,000 VND/kg for cabbage branded “Organic cabbage”, 12,000 VND/kg for “Green cabbage”, and 10,000 VND/kg for "Safe cabbage". In addition, consumers also agreed to pay an additional 14,000 VND/kg for cabbage with traceability.

The study analyzed the perception and identified the demand of Can Tho City residents for the proposed safe rice through the willingness to pay, estimated by the double-bounded dichotomous choice contingent valuation method (DBDC CVM). The results showed that most of the respondents were aware of the benefits of organic agriculture and the existence of food safety problems. The respondents were willing to pay for safe rice at the average price of 22,500 VND/kg, which was 75% higher than the normal rice price (13,000 VND/kg). This study also showed that if the respondents were having their own business, higher education, or income, the possibility of their willingness to pay for the proposed safe rice would become higher.

Rice husk biochar, which was produced at 500oC, 700oC and 900oC to adsorb chlorpyrifos ethyl (CE) in water, was used in this study. Three treatments of rice husk biochar and control treatment (no biochar) were conducted with three replicates. At each replication, one gram (1 g) of biochar was added into 200 mL CE solution and then shook at 125 rounds per minute for 60, 120, 180 and 300 minutes. Afterwards, solutions were filtered through a filter paper. The solution was reserved for analyzing the remaining CE by chromatography. The results showed that rice husk biochar had the ability to adsorb CE quickly during 60 minutes of contact, then adsorption ability was gradually reduced and saturated at 120 minutes in shaking conditions. The average CE adsorption capacity of rice husk biochar was produced at 500oC, 700oC and 900oC in 300 minutes were 303.40±24.10 µg/g, 328.59±1.47 µg/g and 323.68±3.82 µg/g, respectively. Studying the adsorption capacity of rice husk biochar for some other pesticides was necessary to show the applicability of rice husk biochar in the adsorption of pesticides.

This study analyses the current situation of municipal solid waste (MSW) generation, collection, and management in the Mekong Delta (MD) by employing the integrated assessment model DPSIR (Drive forces, State, Impact, and Response). The data used for analysis are secondary data collected directly from local authorities and the KIP approach and, the primary data set was collected by surveying 456 households in the MD. The research results show that although the damage caused by MSW pollution is currently large, the amount generated by day and year is very high, but the collection rate and treatment amount are still limited (from 80% to 87%). Meanwhile, funding for environmental causes (including for MSW) has increased doubled from 2010 to 2015. The main reasons identified include difficulties in accessing new technologies, shortage of human resources, and ineffective management policies. Suggested solutions to improve MSW management include fee-related issues, improving technical solutions and collecting system, implementing the development of recycling technology, and raising public awareness.

The study was carried out with the aim of assessing the physical and chemical properties of soil inside and outside the dike system control flood in the acid sulphate soil at Tri Ton and degraded soil at Tinh Bien. The number of samples randomly collected per soil group was 32 samples, including: 16 samples inside the dike (3-crop rice area) and 16 samples outside the dike (2-crop rice). The results showed that cultivation three rice crops per year inside the dike caused the soil pH lower than the soil pH outside the dike; the EC of the soil inside the dike is higher than the EC of the soil outside the dike. The organic matter content of topsoil horizon (Ap) in the inside the dike (3 rice crops/year) is higher than that in outside the dike (2 rice crops/year). As a result, cation exchange capacity (CEC), the total nitrogen of the soil inside the dike is higher than that in the outside the dike, especially in the surface layer (Ap). Meanwhile, total phosphorus and total potassium content did not show a statistically significant difference between inside and outside the dike in both study sites. The soil compaction of Bg horizon was higher than that in inside the dike compared to outside the dike in both Tri Ton and Tinh Bien study sites, expressed by low soil porosity and soil permeability, high bulk density and soil penetration resistance.

The study was conducted to assess the impact of saline intrusion on agricultural farming models in coastal areas of Binh Dai district, Ben Tre province. The data were collected collected through direct interviews of 83 farmers and 12 local officials to assess the impact of saline intrusion on agricultural farming models including shrimp, rice - shrimp, livestock and salt production. The results of the study show that the livestock and rice-shrimp models are strongly affected by saline intrusion.The shrimp monoculture and salt production models are slightly affected, so these models can be seen more suitable for cultivation in longer saline conditions than the other modelsTo reduce the adverse effects of saline intrusion, 60% of  rice-shrimp farmers interviewed chose to switch farming models to shrimp farming, 15% choose non-cultivated  to limit risks and the remaining 25% of households to farm normally. Therefore, local authorities need to study and transfer production models adapted to saline intrusion to ensure livelihoods for local people, adapting to saltwater intrusion that may be complicated in the future.

The study was conducted to compare some environmental parameters of soil quality in cultivation models in freshwater areas in An Thanh I commune, Cu Lao Dung district, Soc Trang province in order to provide more information for local agricultural land use planning as well as support local people in developing an care plan for farming models effectively. Soil samples were collected in four farming models, which occupied a large area in the study site including whiteleg shrimp pond, coconut garden, longan garden and mango garden. The study was conducted during the rainy season because local people start a new crop at this time. Research results show that the soil EC value recorded is in the average range (0.889 – 4.32 dS/m), soil pH ranges around 4.5 - 5.5 considered acidic soil. Parameters of total nitrogen (0.133 – 0.168%) and total potassium (0.15 – 0.20%) are in the average - high level, the average value of total phosphorus (0.044 – 0.053%) in the soil is low. It is essential to have a suitable plan of crop conversion for acidic and salinity soil areas in order to increase productivity and income for the community in the research site.

The research aims to define the status of plastic waste disposal and propose solutions for reducing plastic waste at Can Tho University. Types of plastic waste and plastic types in plastic waste were disposed from classrooms and on-campus that were surveyed from September 2020 to January 2021. The survey on the use of plastic products and solutions for reducing plastic waste disposal was also conducted by interviewing staff (n = 108), students (n = 600), and sellers (n = 15). The results showed that in terms of weight, plastic waste accounted for 11,4% of total weight of solid waste, and plastic with the type of LDPE was disposed of the most (44.3%) on campus. LDPE plastic bags were disposed of the most from classrooms which accounted for 31,9% of total types of plastic waste. Most (80%) of the sellers did not separate plastic for recycling or scrap. The limitation of propaganda, the convenience of plastic products, and the un-classification are the main difficulties in reducing plastic waste disposal. Integrated ways include propaganda, solid waste separation, reward and sanction such as lowering student’s grades for extra curriculum activities, and research on plastic waste recycling model need to be conducted to reduce plastic waste disposal.