Adaptation Tipping Points to Salinity Management for Boro Rice Cultivation in South West Bangladesh.

Adaptation Tipping Points to Salinity Management for Boro Rice cultivation

in South West Bangladesh

Md Aminul Islam[1] and Fulco Ludwig[2]

Abstract

Due to a combination of sea level rise, reduced dry season river flows and land use change salt water intrusion in becoming a large problem in the Bangladesh Delta. The increased salt concentrations in surface and ground water can potentially have a large impact on crop production. The aim of the present study was to identify threshold salinity levels and tipping points for salinity management in Boro rice at Satkhira district in South-West Bangladesh. Primary data were collected through a questionnaire survey, focus group discussion to identify farmers' perception on critical growth stages of Boro rice as affected by soil salinity. Survey results were harmonized with literature review and experts opinion. The results show that panicle emergence stage is the most vulnerable growing period of rice. During this growth stage, higher salt concentration results in lower yield of rice. Based on our results salinity thresholds were defined as 4-5 dS/m for traditional Boro rice varieties and 8-10 dS/m for newly released salt tolerant varieties. In South-West Bangladesh panicle emergence of Boro rice is takes place in March to April. During the same period, salt intrusion reaches its peak in this region. Salinity level in the study region is the highest during the most vulnerable growing stage of Boro rice. Based on the results we conclude that for traditional Boro rice varieties tipping may have already reached in the areas closes to the coast. For salt tolerant varieties tipping may be reached in the near future. Not only future climate change but also conflicts of interest between rice and shrimp farming may accelerate reaching tipping points and Boro rice cultivation will be threatened by future salt intrusion and high profitable shrimp farming in future.

Key words: Bangladesh, Boro rice, vulnerable growing period, panicle emergence, salinity threshold, tipping points

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[1] Earth System Science Group, Wageningen University, the Netherlands and currently doing Internship at IAREC, Washington State University

[2] Earth System Science Group, Wageningen University, the Netherlands