Agriculture: Climate change might already be affecting rice yield in Bumthang going by an increasing reports of yield decline although ADB’s recent report on assessing climate change costs in south asia predicts rice yield to decline only by 2050 for Bhutan.
While ADB’s recent report predicts rice yield to increase in higher altitudes until 2030 because of gradual rise in global temperature, rice yield in Bumthang, which is located 2650masl is rather declining since 2012.
Only scientific research might tell if it’s really climate change behind the yield slump but rice growers are already grappling with waning yield ssince 2012.
Following reports of declines in yield in Wangdi Chhoeling and the Jambay Lhakhang area, the Renewable Research and Development Centre (RRDC) in Bumthang recently released a new climate resistant rice variety, JRN White.
“JRN White was issued following reports of decline in the yield from the only variety grown in Bumthang, Jakar Ray Naap,” RRDC senior researcher, Rabgyel Dukpa said. He added that JRN White was distributed after rice growers agreed to try for an alternative variety if Jakar Ray Naap failed.
JRN White is considered climate resistant because of its resistance to climate change induced pests, diseases and changing weather conditions. “JRN White’s yield of 2.2 tonnes per acre is also the highest amongst the six varieties grown on-station in the centre,” Rabgyel Dukpa said.
RRDC was growing on-station six rice varieties such as JRN White, Chandanath I, Chandanath III, JRN Awn and Khangma Maap. “These varieties were grown in on-station to replace if by chance Jakar Ray Naap failed because of diseases of pests with changing weather conditions,” Ranbgyel Dukpa said.
Though Jakar Ray Naap is still the preferred variety among many farmers of Tang and Choekhor, JRN White was introduced for the rice growers of Wangdi Chhoeling and Jambay Lhakhang areas, where the yield was reported declining.
In Wangdi Chhoeling, Karma Yangzom’s rice yield from a field as big as a basketball court decreased to around 600kgs from over 1,500kgs before. “Yield has never been so poor like this year,” Karma Yangzom said.
Her neighbour, Yeshey, harvested only around 200kgs of rice from a field the size of a football pitch.
Results from the RRDC on-station also showed that the yield from JRN, which initially produced 2.2-2.4 tonnes of rice per acre in 2003 dropped to 2.2 tonnes per acre over the years.
According to rice growers the decline in yield is caused by an unfamiliar disease, which is affecting the rice plants during grain formation. “There are only empty husks since grain formation was affected from dying saplings,” Karma Yangzom said.
A rice grower from Jalikhar, Sonam Tobgye attributed the new diseases to rising temperatures in the dzongkhag. “Because now the temperature in Bumthang is getting as warm as Trongsa, plant diseases, which we have never seen before in rice is now making its way here,” he said.
Rabgyel Dukpa said while multiple factors are causing the declining yield, one specific reason was Whitehead infestation, which was seen in the rice fields of Bumthang only in recent years.
“Whitehead affects the grain formation leading to empty husks,” he said, adding climate change could likely have had a role because rice cultivation in Bumthang is possible because of the rising temperature.
Rice cultivation in Bumthang began only in 2003. Its cold whether conditions made rice cultivation unfavourable although attempts were made as far back as 70 years ago. “But without scientific study neither can the decline in rice yield be attributed to climate change nor can it be absolved as a factor,” Rabgyel Dukpa said.
Nevertheless, dzongkhag agriculture officer, Gaylong said numerous factors could be responsible for the poor yield. “Diseases, degraded soil fertility over the years, excess nitrogen and poor management of water and cultivation could also have led to yield loss,” Gaylong said.
He added that the disease is not necessarilyclimate change induced as it could have spread through a nursery in Trongsa used for paddy cultivation in Bumthang. “To prevent spread of soil diseases and blast by growing nursery in lower altitudes, polythene sheets has been issued to the farmers here to enable nursery raising in Bumthang,” Gaylong said.
Over 30kgs of JRN White will be cultivated on trail from 2016.
The research centre has also distributed Chandanath I to the farmers to study its viability.
Tempa Wangdi, Bumthang