Around 1,600 litres of water is needed to produce one kilogram of Boro rice in the country’s north-western region, the Bangladesh Rice Research Institute (BRRI) says.
The total range of supplied water use was 955-2,599 litres per kg rice. In 75 per cent cases, the provided water varied from 1,296-1,821 litres per kg rice with an average of 1,606 litres in 2015-16 and 2016-17.
The average irrigation water supplied to the field was 1,402 litres per kg in 2015−16 and 1,086 litres in 2016−17.
“Irrigation water means the water given to the plots from irrigation facilities. If there is not enough rain, we have seen that 1,400 litres is enough,” Md Moniruzzaman, principal scientific officer (irrigation and water management division) of BRRI told The Business Post.
BRRI is going to publish the findings on January 16 in a webinar. There is a misconception that 3,000-5,000 litres are needed to produce 1kg Boro rice.
“There are some misconceptions on the amount of water used in Boro cultivation. The figure we are providing is scientific and the findings of a state-of-art research method,” Moniruzzaman said.
Actual crop evapotranspiration is the actual water use. In this sense, the actual water consumption is 584 litres. Percolation and seepage water return to the underlying aquifer.
This study provides a comprehensive account of these aspects of Boro rice cultivation based on field observations at 420 farmers’ plots in 2015–16 and 2016–17 across Thakurgaon Sadar, Tanore of Rajshahi, Kaharol of Dinajpur, Mithapukur and Badarganj of Rangpur, Sherpur of Bogura, and Ishurdi of Pabna.
Researchers also recorded necessary data, including land type, soil type, rice varieties, seeding and transplanting times, grain and biomass yield pump discharges, and irrigation amount.
The total irrigated area is 5.58 million hectares (Mha), of which about 57 per cent was irrigated by shallow tubewell, 19 per cent by deep tubewell and 24 per cent by low lift pump.
Rice covered about 80 per cent of the total irrigated area. Boro rice uses most of the irrigation water. In the north-west region, 97 per cent of irrigation is from groundwater.
The total Boro rice area is about 4.8 Mha, of which about 1.6 Mha are in the north-west region.
In the last decade, the average Boro rice yield was 6.5-7 tonnes per hectare, while Aman production was 4.5- 5.0 tonnes per hectare. BRRI Dhan 29 and hybrid had the highest yield.