Nature-based solutions needed to control cadmium in durian

Essential to monitor and early address soil residue risks

Viet Nam's durian industry is entering a period of strong growth, with an area of around 195,000 ha, an output of approximately 1.8 million tons, and export turnover in 2025 estimated at nearly USD 3.86 billion. However, alongside rapid area expansion and intensive cultivation, pressure to control quality, particularly heavy metal residues, is becoming an urgent requirement.

According to preliminary research findings from the Southern Fruit Research Institute, cadmium (Cd) has been detected in several durian-growing areas. Although most soil and durian flesh samples remain within the safety limits set by Vietnamese standards, the risk of exceeding control thresholds of import markets is raising the urgent need for early monitoring and intervention.

In particular, the Chinese market currently requires cadmium content in durian flesh to remain below 0.05mg/kg. This is considered one of the major technical barriers facing durian exports. According to the Southern Fruit Research Institute, cadmium contamination in agricultural soils may originate from multiple sources, including inorganic fertilizers, especially phosphate fertilizers, agricultural inputs, environmental waste, and prolonged cultivation processes.

Survey results from 63 soil samples collected in durian orchards in 2025 showed that around 60% exceeded 0.05 mg/kg of soil. However, all samples remained far below Viet Nam’s agricultural soil norm under QCVN 03:2023/BNNMT, which sets the limit at 4mg/kg of soil.

Among more than 300 durian flesh samples analyzed, only around 5% exceeded the 0.05mg/kg threshold required by the Chinese market. The findings indicate that the risk has emerged but is not yet widespread.

In Dong Thap, specialized agencies surveyed 115 durian-growing areas granted planting area codes to assess the risk of cadmium residues in soil. Of these, 17 areas showed no detectable cadmium, 53 areas recorded levels below 0.1 mg/kg, 31 areas ranged from 0.1 to 0.2 mg/kg, 10 areas from 0.2 to 0.3 mg/kg, and four areas exceeded 0.3mg/kg. Nevertheless, all samples remained well below the current regulatory threshold for agricultural soils.

According to the research team, soil pH has a major influence on the crops’ ability to absorb cadmium. Survey results showed that the closer the soil is to neutral pH, the lower the risk of cadmium uptake by plants. This is considered an important basis for developing appropriate soil improvement and nutrient management solutions for durian-growing areas.

Dr. Vo Huu Thoai, Director of the Southern Fruit Research Institute, said that in newly developed durian-growing areas, farmers should cooperate under standardized cultivation processes that have been verified and recognized as safe and effective. According to Mr. Thoai, farmers should also proactively test soil cadmium levels in order to take early remedial measures if residue risks are detected.

A cadmium risk map needs to be developed soon

Based on the research findings, the Southern Fruit Research Institute has proposed numerous biological and nature-based solutions to reduce cadmium absorption in soil and durian fruit.

Recommended solutions include raising soil pH with lime, increasing the use of organic fertilizers, limiting the overuse of chemical fertilizers, especially phosphate fertilizers, controlling the quality of agricultural inputs, and applying biochar to absorb cadmium in the soil.

In addition, the application of microbial products that can immobilize cadmium and improve soil microbial activity is considered a suitable approach aligned with the development of low-emission agroecology.

Beyond technical measures, experts have recommended the early development of cadmium risk maps for key durian production regions, strengthened monitoring of heavy metal levels in soil, irrigation water, fertilizers, and products, and the development of biological and low-emission cultivation protocols to reduce cadmium absorption.

The research team also proposed intercropping with plants capable of absorbing cadmium, such as water spinach, amaranth, mustard greens, water hyacinth, and aquatic ferns, to help remediate the soil. After each cultivation cycle, plant biomass should be collected and properly treated to prevent cadmium from being released back into the environment.