Bimkhar village under Trashi Yangtse Dzongkhag is situated at the east of the Yangtse RNR Extension Centre consisting of 65 households. The village has good access to farm road, electricity and other developmental activities.  The people of Bimkhar village grows a variety of vegetables, of which Urka chili is a major cash crop for the community. Besides, the farmers also cultivate paddy and millet as a staple crop for their consumption, and rear livestock like cattle and poultry for sustaining livelihoods.

In the recent years, with better access to the market, numerous farmers’ groups such as the Vegetable Farmers’ Group, Urka Bangala Group (Chili Farmers’ Group) and Gonor Gongphel Doetshen (Dairy Farmers’ Group) has come up in the community, with support from Royal Government of Bhutan (RGoB) and donor assisted projects. Bimkhar Urka bangala group has 26 women members.

Bimkhar farmers’ grow chili as a major crop, producing huge surplus during the season. Although farmers sell the fresh produce right after harvest, there is also opportunity from drying chili which can fetch better price and also reduce post-harvest loss.

Drying chili is common practice in Bimkhar village. Traditionally, farmers spread out chilies on the rooftop or open field to dry under the sun.  However, such traditional process is not efficient and time consuming. Moreover, chilli harvest coincides with the monsoon which makes drying more difficult causing huge post-harvest lost. Therefore, electric dryers supported through Post Harvest Support Programs are also used by some farmers. These electric dryers are effective but it has limitations of space and consumes lots of energy.

The Agriculture Research and Development Centre (ARDC Wengkhar), under Department of Agriculture (DoA) has designed a solar dryer using the conventional greenhouse incorporating exhaust fans operated with the use of solar energy. The model was adapted from the University of Silpakorn, Thailand after a study visit supported by CARLEP – IFAD.

The solar dryer was established at Bimkhar in November 2018 by the Bimkhar Urka Bangala Group with technical support from ARDC Wengkhar in collaboration with Trashi Yangtse Dzongkhag Agriculture Office. The model was built on a cost-sharing basis in which farmers contributed construction materials for shelves, labour for land preparation, local materials such as sand and gravels, poles and fixing of shelves while greenhouse, exhaust fans, solar panels and accessories were provided with fund support from Commercial Agriculture and Resilient Livelihoods Enhancement Programme ( CARLEP – IFAD / MoAF support to Yangtse Dzongkhag Agriculture Sector).  A set of solar dryers with a dimension of 5m x 20m cost approximately Nu. 131,926.

Table 1. Total cost for greenhouse solar dryer 5 m x 20 m with concrete floor

Bimkhar Urka Bangala Group dried around 2,600 kgs of red chillies using the solar dryer since the establishment. Farmers’ reported that the use of solar dryer is more convenient and better than other alternatives like electric dryer. Although, the difference in number of days taken to dry small quantity of chilli is insignificant when compared to electric dryer (difference of 3 days), the number of days in comparison to sun drying is reduced by 50% (15 days sun-drying to 7 days in greenhouse solar dryer). Further, greenhouse solar dryer is also found to be cheaper than electric dryer. The greenhouse solar dryer has more space than electric drier which makes it convenient for farmers to dry large quantity of chili at a time. On comparison, an electric dryer can fit up to 17 kgs to 20 kgs, whereas greenhouse solar dryers can fit up to 650 kgs to 700kgs. Besides the use for drying farm produces, it can be also used for other purposes when not in use for drying.

At a recovery rate of 66% (1 kg fresh = 0.66 kg dried as studied in on-station and on-farm trials conducted by ARDC Wengkhar), Urka chilli in dried form can fetch a high price of about Nu 925 per kg in the local market as compared to Nu. 70 to 80 per kg as fresh chilli. Dried chilli can even fetch up to Nu. 1000 to 1200 per kg if taken to markets like Thimphu.

The returns in chilli can be enhanced significantly through drying for which dryer – both electrical as well as greenhouse solar dryer can benefit chilli growers. A farmer drying about 250 to 300 Kg fresh chilli will be able to break even investments in establishing greenhouse solar dryer in one growing season which can further enable promotion and adoption greenhouse solar dryer technology.

The ARDC Wengkhar in 2018-2019 financial year have replicated a total of five greenhouse solar dryers  in different locations with support from the CARLEP – IFAD / MoAF in collaboration with Dzongkhag and gewog agriculture extension centres and farmers group ( 1 site at Yangtse geog and two sites at Bummdeling geog in Tashiyangtse Dzongkhag, 1 site at Chokhorling geog under Pemagatshel Dzongkhag and another 1 site at Kangpara under Tashigang Dzongkhag). Establishment of solar dryer has benefitted a total of 76 households (25 households from Yangtse gewog, 12 households from Bumdeling, 11 households from Chokhorling and 28 households from Kangpara in Trashigang). The centre and the Dzongkhags should jointly promote this technology to some more villages in the coming year on a cost-sharing basis.

Erratic power supply during cloudy and rainy days is one of the disadvantages of using solar energy for running exhaust fan in solar dryer. This can be addressed by using automatic switch that can connect to electric power line to increase the efficiency.

– Dawa Dema, Pema Lhaden and Kinley Wangmo

(ARDC Wengkhar & IFPP Lingmethang)