Controlling cadmium in durian to establish safe production areas

Testing multiple technical solutions

Cadmium contamination in durian-growing soils has become a growing concern for both the agricultural sector and growers, as many export markets tighten food safety requirements. In response to these increasingly stringent standards, Dong Thap Province has implemented a pilot program applying multiple technical solutions to mitigate cadmium contamination in export-oriented durian-growing areas. Initial results have been encouraging, laying the groundwork for developing safe production zones that meet export requirements.

According to the Dong Thap Sub-Department of Plant Production and Protection, the pilot project was implemented under Provincial People's Committee Plan No. 113/KH-UBND on the issuance and management of growing area codes, packing house codes, and food safety control for export-oriented production areas across the province.

The project was carried out at two sites, Long Tien Commune and Thanh Hung Commune, covering a total of one hectare of Ri6 durian. The Long Tien site spans 0.5 hectares with 12-year-old trees, while the Thanh Hung site covers 0.5 hectares with trees aged five to six years. Both growing areas have been granted official export codes.

To reduce cadmium uptake from the soil into durian trees, the Sub-Department collaborated with Can Tho University and several private-sector partners to implement multiple technical solutions simultaneously. These included the use of ultra-low-cadmium fertilizers, the application of microbial organic fertilizers, intercropping mint in orchards, the use of biological products, and the use of biochar produced from rice husks.

Notably, all organic, inorganic, and foliar fertilizers were tested for cadmium content before being introduced into the pilot project. Only products containing less than 0.3 mg of cadmium per kilogram were approved for use.

According to monitoring results after six months of implementation, soil pH at the Long Tien pilot site increased from 4.5 to 5.0. This is considered a key factor in reducing cadmium solubility in soil and limiting its uptake by durian trees.

In addition, cadmium concentrations in branch and leaf samples declined by 0.02 to 0.04 mg/kg across all treatment methods. Among the solutions tested, the combination of microbial organic fertilizer and biochar produced the most promising results.

Agricultural specialists noted that biochar can adsorb heavy metals in soil, thereby reducing cadmium uptake by plants. At the same time, increasing the use of organic fertilizers and enhancing soil microbial activity helps improve soil structure, restore fertility, and promote more sustainable farming practices.

Beyond technical interventions, the pilot project also encourages farmers to adopt more sustainable cultivation practices by reducing reliance on chemical fertilizers and increasing the use of organic fertilizers and environmentally friendly biological inputs.

Building safe production areas

Despite the encouraging initial results, Dong Thap's agricultural authorities acknowledge that controlling cadmium in durian-growing areas remains challenging due to the lack of in-depth research on how cadmium accumulates and is absorbed in soils and durian trees.

In addition, the wide variety of fertilizers available on the market makes it difficult to comprehensively monitor cadmium levels in agricultural inputs. Many farmers also continue to rely heavily on chemical fertilizers and crop protection products, while soil rehabilitation requires a long-term commitment to achieve meaningful results.

Tran Thanh Tam, Director of the Dong Thap Sub-Department of Plant Production and Protection, said the outcomes of the two pilot projects provide an important foundation for further refining cadmium control protocols in export-oriented durian-growing areas.

According to Tam, the Sub-Department will continue strengthening oversight of growing areas and export packing facilities while working closely with local authorities and businesses to enhance monitoring across the supply chain. These efforts aim to ensure that exported durian complies with food safety standards and traceability requirements.

Under the strategic direction of the Dong Thap Provincial People's Committee, localities with significant durian cultivation areas will collaborate to develop model production zones aimed at keeping cadmium levels in durian fruit below 0.05 mg/kg, in line with export requirements.

The Dong Thap Durian Association is also encouraged to strengthen partnerships among businesses, cooperatives, and growers to establish a sustainable durian value chain that spans production, post-harvest handling, and market distribution.

For growers, agricultural authorities recommend increasing the proportion of organic fertilizers to 60:40 or 70:30 relative to inorganic fertilizers. This approach is expected to restore soil health, reduce the risk of heavy metal residues, and improve the quality of durian fruit.

According to the Dong Thap Department of Agriculture and Environment, the province currently has more than 32,100 hectares of durian cultivation, with annual production exceeding 511,000 metric tons. A total of 355 growing area codes have been issued, covering more than 13,900 hectares. In May and June 2026 alone, durian harvest output was estimated at more than 111,200 metric tons.