Sy-Nam Tran

The reuse of biogas effluent (BE) represents a sustainable approach for nutrient recycling in agricultural systems, particularly in regions with intensive livestock production. However, its application is often limited by low nutrient concentrations and inefficient management based on total...

The Mekong Delta is a flood-based agricultural landscape whose productivity depends strongly on sediment deposition. This study evaluated the quantity and quality of flood-borne sediments in Tinh Bien district, An Giang province, across upstream, behind the Melaleuca forest, and downstream areas....

Biogas production from cattle manure offers a promising and sustainable solution for managing livestock waste in the rural areas of the Vietnamese Mekong Delta (VMD), where smallholder cattle farming is common. The study aims to evaluate the impact of organic loading rates (OLR) of cattle manure...

Methanotrophs and biochar have emerged as a promising strategy for mitigating methane (CH ₄ ) emissions from rice cultivation. However, their application in biogas digestate effluent (BDE)‐fertilized systems remains poorly understood. Here, we evaluated the effects of methanotroph‐inoculated biochar (BEMB) on soil properties, rice growth, grain yield, and CH ₄ emissions under BDE fertilization. Throughout the growth cycle, this study monitored soil physicochemical parameters, agronomic traits, and CH ₄ fluxes. This study conducted a principal component analysis (PCA) to identify relationships among soil, plant, and emission variables. The results indicated that BEMB tended to improve soil nutrient retention, with higher NH ₄ ⁺ concentrations and a trend toward increased soil organic carbon (SOC). Additionally, BEMB increased plant height while maintaining panicle density and grain yield, and reduced total CH ₄ emissions by 21.6%–42.5% and yield‐scaled CH ₄ emissions by 23.7%–46.4%, with the greatest reductions at 50% BEMB application. PCA results showed that the interactions between soil carbon and nitrogen, along with water level, are the primary factors influencing CH ₄ emissions. The incorporation of BEMB shifted the system toward higher productivity while decreasing CH ₄ flux intensity. These findings suggest that adding biochar preinoculated with methanotrophs into rice systems treated with BDE is a promising low‐carbon management strategy for sustainable paddy cultivation. Future field‐scale trials are recommended to validate its long‐term agronomic feasibility and CH ₄ mitigation potential under varying soil and climatic conditions.

Sediment deposition in the Vietnamese Mekong Delta (VMD) has declined sharply due to high‐dike infrastructure and upstream damming, threatening long‐term soil fertility and agroecosystem resilience. This study presents the first integrated assessment of sediment dynamics and soil health across four flood‐based and conventional agricultural systems in VMD. We compared sediment accumulation and soil biochemical properties in (1) floating rice–fish farming, (2) lotus–fish farming, (3) natural flooding, and (4) triple‐rice cropping systems. Sediment samples ( n = 80) and soil samples ( n = 35) were collected from 2022 to 2024. We applied principal component analysis (PCA) to identify a minimum data set of soil indicators and used a weighted soil health index (SHI) to evaluate system performance. Nonparametric Kruskal–Wallis tests revealed statistically significant differences in sediment mass, nutrient retention, and soil health among models ( p < 0.001). The lotus–fish and natural flooding models exhibited 8–15 times greater sediment deposition and SHI values that were 25%–33% higher than those of the triple‐rice system, with strong correlations between sediment mass and soil health ( R ² = 0.613). These models also enable reductions of up to 40% in postflood nitrogen and potassium fertilizer requirements. Using PCA and a weighted SHI framework, we highlight that flood‐based systems, particularly lotus–fish farming, significantly enhance soil health and reduce fertilizer dependency. Our results support the scaling of sustainable agricultural transitions in line with Vietnam’s Resolution 120 on climate‐resilient development in the VMD.

Nghiên cứu về thành phần loài cá tại vùng lõi và các cống lấy nước đầu vào của Khu bảo vệ cảnh quan rừng tràm Trà Sư được thực hiện qua 03 đợt thu mẫu từ tháng 8 đến tháng 11/2023. Mẫu cá được thu trực tiếp bằng lưới dìm (lưới chụp) và lú đuôi chuột. Phương pháp thống kê mô tả và các chỉ số đa dạng sinh học được sử dụng trong nghiên cứu để so sánh thành phần loài giữa hai khu vực thu mẫu. Kết quả cho thấy có 36 loài cá thuộc 17 họ và 7 bộ được xác định tại các cống lấy nước, chủ yếu là các loài cá di cư theo mùa lũ. Trong khi đó, vùng lõi chỉ ghi nhận được 14 loài cá thuộc 8 họ và 4 bộ với phần lớn là các loài cá bản địa. Kết quả cũng cho thấy, ở vùng cửa cống có mức độ đa dạng sinh học khu hệ cá cao hơn vùng lõi thông qua chỉ số H’, Dmg và Cd. Chỉ số tương đồng Sorensen cho thấy chỉ có 8 loài cá cùng xuất hiện ở cả hai khu vực thu mẫu (chiếm 19%). Từ đó phản ánh rằng, thành phần loài cá trong vùng lõi Trà Sư có sự khác biệt đáng kể so với thuỷ vực bên ngoài, với sự chiếm ưu thế của nhóm cá bản địa thích nghi tốt trong điều kiện nước tĩnh.

Biogas digestive effluent (BDE) is a nutrient-enriched source that can be utilized as an organic fertilizer for rice cultivation without synthetic fertilizer (SF) application. However, a primary concern is the stimulation of methane (CH₄) emissions due to the enrichment of the labile organic carbon, a favorite substrate of methanogenic archaea. Methanotrophs potentially reduce greenhouse gas (GHG) emissions from rice fields owing to metabolizing CH₄ as a carbon source and energy. We therefore examined the effect of the application of methanotroph-inoculated BDE to the rice cultivated paddy soil on GHG emissions and rice productivity under a pot experiment. Methanotrophs (Methylosinus sp. and Methylocystis sp.), isolated from the Vietnamese Mekong Delta’s rice fields, were separately inoculated to the heated BDE, followed by a 5-day preincubation. Methanotroph-inoculated BDE was supplied to rice cultivation to substitute SF at 50% or 100% in terms of nitrogen amount. The results showed that the total CH₄ emissions increased ~34% with the application of BDE. CH₄ emissions were significantly reduced by ~17–21% and ~28–44% under the application of methanotroph-inoculated BDE at 100% and 50%, respectively. The reduction in CH₄ was commensurate with the augmentation of pmoA transcript copy number under methanotroph-inoculated BDE. In addition, methanotroph-inoculated BDE application did not increase nitrous oxide (N₂O) emissions and adversely affect rice growth and grain productivity. This study highlighted the BDE-recirculated feasibility for a lower CH₄ emission rice production based on methanotrophs where high CH₄-emitting fields were confirmed.