Kolkata: A Bengal-based researcher has developed 24 experimental sites across the Gangetic belt, including several in Bengal, where farmers have been successfully sensitised to adopt the Alternate Wetting-Drying (AWD) technique in cultivation to significantly reduce arsenic (As) contamination in soil.
The research assumes special importance for Bengal, where arsenic contamination has long posed a serious environmental and health challenge, but public awareness and mitigation measures remain limited. Arnab Majumdar, a member of the Royal Society (UK) and currently an MSCA Post-Doctoral Fellow at Imperial College London, conducted field trials across the Gangetic belt—covering Bengal, Uttar Pradesh, Uttarakhand and Bihar—over a 2,200 km stretch. He developed 24 experimental sites (six in each state), where he demonstrated to farmers how AWD could be a more sustainable and efficient alternative to the traditional irrigation method of keeping paddy fields continuously flooded.
In Bengal, the experimental sites were located in Lalgola, Murshidabad, Katwa, Kalyani, Diamond Harbour and Kakdwip. Under the traditional system, arsenic levels in paddy soil can reach 800-1000 ppm, far above the permissible limit of 100 ppm. However, under the AWD system, the contamination was found to be between 150 and 220 ppm, only marginally higher than the limit.
Majumdar said this reduction was achieved in about 30 months and projected that arsenic levels would fall within the permissible limit if the technique were used consistently for 7-8 years.
“An economic study revealed that rice productivity profit through AWD exceeds Rs 10 lakh (1 million) per hectare, with major savings in electricity and significant water conservation benefits,” said Majumdar.
He added that AWD resulted in 15-fold water savings and 6-8 per cent higher profit. The soil’s microbial community also showed greater tolerance to arsenic, improving overall soil health and crop quality. Around 170 farmers across the four states—about 6-7 per site—have already adopted the AWD method and are being encouraged to spread the technique further within their communities.
Majumdar’s findings have been published in the Journal of Hazardous Materials (2021 and 2024), and subsequently in Science of the Total Environment and Soil and Tillage Research.