Cultivation of a new rice variety, BRRI Dhan 75, followed by mustard variety BARI Sorisa 14 before planting another rice variety, BRRI Dhan 28, in the next season in some climate-vulnerable areas of Bangladesh would decrease production cost and greenhouse gas emission.
International Rice Research Institute (IRRI) and Asian Development Bank (ADB) have named this rice cultivation method as "climate-smart production practices" that include the application of balanced fertilisers, alternate wetting and drying technology and mechanised harvesting.
In the recent study "Climate-Smart Practices for Intensive Rice-Based Systems in Bangladesh, Cambodia and Nepal," the two organisations said dwindling agricultural resources, rising farmers' wages, extensive use of water and climate change are emerging as the main problems to rice production in Asia.
The study has been conducted with the reviews from several ADB-funded projects, including the Alternative Wetting and Drying (AWD) Varieties and Management Practices in Muhuri Irrigation Project implemented in 2016-17 in Chattogram and Feni around the confluence of the Feni, Muhuri and Kalidash–Pahalia rivers.
According to the study, the climate-smart practices increased farmers' income by 52 to 61 percent. In Bangladesh, the AWD technology required about 22 percent less water compared to the continuous standing water irrigation system.
Department of Agricultural Extension's crops wing Director Abdur Razzak told The Business Standard that climate-smart production practices would help transform croplands from current two-crop to four-crop.
"BRRI Dhan 75 is a short duration variety (115 days), while BRRI Dhan 28 and 81 require 130 to 140 days to ripe. If the varieties get popularity, production time would reduce, so would the production cost," Razzak said.
The smart practices help save insect management cost amounting to Tk3,893 per hectare and decrease labour cost up to Tk7,000 per hectare, said the study.
BRRI Dhan 75 yielded 20 percent higher – 5.11 tonnes per hectare – than the normal varieties.
BRRI Dhan 11 and BRRI Dhan 49 cultivated during the transplanted Aman season (November-December) yielded 4.26 tonnes per hectare, the study revealed.
It also found BRRI Dhan 75 had the lowest greenhouse gas emission – 44kg per hectare – while the BRRI Dhan 11 had the highest – 50kg per hectare.
Bangladesh Rice Research Institute, Bangladesh Agricultural Research Council, Bangladesh Agricultural Research Institute, Department of Agricultural Extension, Ministry of Agriculture and Bangladesh Water Development Board were the partners with the study.
Dr Md Nasim, the principal scientific officer of BRRI's rice farming system division, told The Business Standard that the alternate wetting and drying is a proven technology that reduces greenhouse gas emission and water uses in irrigation.
"Practising this technology requires control over irrigation through water pumping. As farmers pay for seasonal irrigation in advance to pump owners, they are used to cultivating rice under continuous standing water. If a cooperative system is developed among farmers, they could practise this technology," Nasim said.
In Bangladesh, irrigation is available in 45 percent of the cultivable areas which are most vulnerable to climate change. Flood and submergence adversely affect more than 66 percent of the lands followed by drought 25 percent and salinity 13 percent.
In this situation, sustainability is a concern, especially given the relatively small size of landholdings, meagre resources, limited technological know-how and low or insufficient use of appropriate farm input.
The study recommended that the Department of Agricultural Extension and the Bangladesh Agricultural Development Corporation strengthen their delivery mechanism to play a better role in multiplication and distribution of climate-smart rice varieties and technologies.
Working in partnership, the Bangladesh government could set up a platform of different stakeholders to support climate-smart agriculture in the country, the study added.