Greenhouse gas emissions from dry season rice irrigation in Bangladesh

Pumping groundwater for irrigation in Bangladesh is a major energy-consuming process and mostly depends on diesel fuel, which is related to greenhouse gas (GHG) emissions. But that issue has not yet been addressed in Bangladesh. `In this study, we have estimated GHG emissions for dry season (DS) irrigated rice considering all irrigation devices with their lifting heads, area coverage, and water sources (surface and groundwater) and power sources (diesel and electricity) during 2019-2020. GHG emissions varied with locations, sources of irrigation, fuel and water sources used. Irrigation water driven GHG emission in Bangladesh is about 2.27 million tons (Mt) CO2e DS-1, which is about only 4% of agricultural sector GHG emission. Groundwater pumps contributed the lion shares (2.04 Mt CO2e DS-1), and surface water pumps contributed only 0.23 Mt CO2e DS-1. Based on the GHG emissions, Rajshahi Division is the main hotspot followed by Rangpur and Mymensingh Divisions, because of intensive groundwater used in these areas. Current deep tubewells (DTWs), shallow tubewells (STWs) and low lift pumps (LLPs) area coverage is about 19.2%, 56.8% and 24.0% of the total cultivable areas of the country; but it contributes about 49.1%, 40.6% and 10.3% of emitted GHG, respectively. The results revealed that withdrawal of groundwater is an important source of GHG emission. Therefore, expansion of surface water irrigation facilities with the adoption of different improved distribution systems, water and energy saving technologies like alternate wetting and drying practices, conservation agriculture along with water use-efficient varieties for rice cultivation can be promoted for reducing GHG emission.