Passive solar greenhouses: How Ladakh farmers are harvesting `crops of hope’ in bone-chilling winter

Srinagar: As the icy-cold winds howl against the barren hills of Ladakh, Dechen Angmo’s vegetable garden, a passive solar greenhouse, comes as a solace in the dark winter. It provides him with homegrown vegetables in freezing temperatures.

“Never in my wildest dreams had I imagined growing vegetables such as cauliflower, broccoli, and highly temperature-sensitive crops like tomatoes in the winter months. But with the help of Ladakh greenhouse, a passive solar greenhouse, it has become possible and also allows enhancing my income,” he said.

Dechen is not the only one who has benefitted from passive solar greenhouses. The concept is catching up fast with the farmers who are keen on growing different types of vegetables in winter months when vegetable availability is scarce in the region.

Ladakh remains cut off for over six months in a year due to heavy snowfall. Availability of locally grown fresh vegetables is restricted to summer months and therefore, there are seasonal differences in dietary intake of food.

“In absence of locally grown vegetables, the people have to procure vegetables from outside the region through goods trucks that come from Manali (480 km) and Srinagar (420 km) and cargo planes from Delhi or Chandigarh where the freight costs sometimes go up to Rs 110 per kg. Also, the vegetables are not that fresh as they reach there,” Dr. Tesring Stobdan, Senior Scientist at the Defense Institute of High Altitude Research (DIHAR) told The Kashmir Monitor.

To address this recurring problem, the Defence Institute of High Altitude Research (DIHAR) came up with the concept of passive solar greenhouses—a type of greenhouse heated entirely by sunlight, with no additional fuel-based heating. The collected solar energy is used for heat and photosynthesis.

“Passive solar greenhouse has played a significant role not only in the production of leafy vegetables in sub-zero temperatures during winter months but also helped in extending the growing season in Ladakh. It is now a common practice to raise vegetable nurseries in spring and grow leafy vegetables during winter months in the greenhouse,” Dr. Stobdan said.

Each year an average of 733 greenhouses covering 44313.4 m2 area are being established in the Leh district. Passive solar greenhouse structures such as Ladakhi greenhouse, trench, polytrench, polyench, polycarbonate, FRP, and polynet have been designed and tested in the inhospitable environment of trans–Himalaya.

However, the course of true love never ran smoothly. Over the years, farmers have begun to feel several issues about different models of greenhouses.

“The concerns emerged with the first iteration of the Ladakhi Greenhouse. Certain vegetables like tomatoes, capsicum, cauliflower, cabbage, pumpkin, and broccoli couldn’t grow because of freezing temperatures at night inside the greenhouse during winter months. During summer months, there was the issue of excessive heat generation inside the greenhouse with temperatures inside rising to a whopping 64 degrees Celsius. Farmers either would remove the cladding material or not use the greenhouse altogether during the summer season,” the research paper titled, “Passive Solar Greenhouse for Round the Year Vegetable Cultivation in Trans- Himalayan Ladakh Region, India, said.

Dr. Stobdan noted that to overcome these difficulties, they started working on a new model of the passive solar greenhouse—Ladakh greenhouse in 2014. It took them many untiring efforts of three years to come up with the first functional prototype.

“Our criteria for a functional greenhouse is growing tomatoes, a highly temperature-sensitive crop during winter seasons without any external heat/power source. In December 2017 we grew tomatoes inside the greenhouse for the first time. The new design was then studied further during the winter and summer for growing a variety of vegetables in Leh Ladakh. Our successful trials led to the designing of improved greenhouses of different sizes to meet varied farmer requirements based on the availability of land and resources,” says Dr. Stobdan.

The Ladakh greenhouse model has been adopted by 600 farmers so far. “It’s a bit costly but offers long-term benefits. Besides, the Government of India is giving a 75 percent subsidy to the farmers emulating this model,” Dr. Stobdan said.