The study, led by Dr Nguyen Thanh Tuan of the Viet Nam National Museum of Nature (Viet Nam Academy of Science and Technology), carried out the project titled “Research to identify soil organic carbon reservoirs in the Red River Delta for monitoring soil quality and greenhouse gas emissions from land”.
According to Dr Tuan, soil functions both as a carbon reservoir and a terrestrial source of carbon emissions. Soil organic carbon (SOC) is primarily formed from organic matter including fallen leaves, dead roots, microorganisms, and decomposed humus.
This component determines soil fertility, helping soil particles bind more effectively, retain water for longer, and supply nutrients as a food source for soil-dwelling organisms. When soil retains organic matter, carbon is stored long-term rather than being decomposed and released into the atmosphere as CO2 — a principal gas driving global warming.
Baseline SOC data is essential for the Red River Delta, where land resources have experienced substantial fluctuations in both area and quality due to natural and human impacts, including industrial and urban development, salinisation, acidification, washout, waterlogging, and soil depletion. These pressures affect the soil’s capacity to store organic carbon.
The research group therefore prioritised quantifying SOC reserves to create a baseline for tracking annual increases and declines, spatial distribution, and key influencing factors. This evidence supports authorities in designing methods to increase SOC stocks in soil and reduce greenhouse gas emissions.
Key findings from the study identified SOC content comprehensively. SOC reserves were recorded at approximately 35.68 tonnes per hectare in the 0–20 cm soil layer, 48.28 tonnes per hectare at 0–30 cm, and 97.02 tonnes per hectare across the 0–1 m soil profile.
Differences among soil groups were notable. Grey, depleted soils on ancient alluvium stored only 74–87 tonnes per hectare, whereas saline and deep acid sulphate soils recorded higher reserves, ranging from over 120 to more than 150 tonnes per hectare.
These measurements represent the first dataset confirming the Red River Delta’s function as a natural sink for soil organic carbon absorption.
To perform rapid SOC assessment, the research team successfully applied Visible and Near-Infrared Spectroscopy (VIS–NIR) combined with mathematical modelling to replace conventional chemical analysis methods that are cost-intensive and carry negative environmental impacts.
The group used handheld spectrometers to scan spectral reflectance for all collected soil samples throughout the region’s provinces. Soil spectral reflectance signals captured in the 350–2,500 nm range were processed and used in mathematical models to develop rapid SOC content estimates for each sample.
At the regional scale, the group also pioneered the use of artificial intelligence and remote sensing data to map SOC distribution in the 0–20 cm soil layer in the provinces of former Thai Binh, Nam Dinh, and Hung Yen, forming key technical prerequisites for emission inventories and carbon credit calculations.
Additionally, the project identified several bacterial and fungal strains with strong organic decomposition activity, opening bioproduct research avenues aimed at enhancing SOC accumulation in soil.
From these findings, the research group proposed the development of scientific foundations and policies for support. First, agricultural land management mechanisms and use policies must encourage sustainable cultivation models including organic agriculture, circular agriculture, green farming, and climate-adaptive systems.
These approaches have demonstrated performance in increasing SOC stocks while reducing greenhouse gas emissions from farmland.
The group also recommended a structured testing pathway to fully assess the deployment of technical solutions aimed at boosting SOC stocks in specific farming systems, including rice paddies, vegetable fields, short-term industrial cropland, and orchards.
Testing models must be deployed both at household farm scale and larger scales to evaluate efficacy in emissions reduction, scalability, and impacts on productivity.
The project further proposed the standardisation and regular updating of SOC data metrics, covering soil layers, soil types, and soil use models, to support regulators in tracking soil quality fluctuations and providing key technical conditions for agricultural carbon credits and future carbon credit trade markets.
Additionally, the group emphasised key coordinated deployment, particularly across regulators, research institutes, universities, and businesses; training for farmers on SOC-enhancing cultivation; and mobilising societal resources to scale the use of advanced technology in analysing and inspecting soil carbon, particularly in light-spectrum analysis technology and machine learning methods.
Dr Nguyen Thanh Tuan confirmed that when Viet Nam’s carbon credit trade market becomes operational, the research outcomes help create favourable conditions for residents, organisations, and enterprises involved in agricultural production in the Red River Delta to participate in, and benefit from the carbon credits generated. In the longer term, these contributions support the national and global Net Zero 2050 goals in agricultural production.
