Designed and developed by a team of researchers from the National Defense High Altitude Research Institute (DIHAR) led by senior scientist Dr. Tsering Stobdan, Ladakh farmers now have a passive solar greenhouse that allows them to grow vegetables year-round.
In Ladakh, the supply of locally grown fresh vegetables is usually limited to the summer months because the area is characterized by drastic temperature changes, especially during the long and harsh winter when temperatures are as low as -30°C. (The picture above is a farmer who grows tomatoes in a greenhouse in Ladakh)
These long winters reduced the crop season to only four or five months a year. Other factors include low precipitation mainly in the form of heavy snow, high wind speeds, sparse plant density, a thin atmosphere with large amounts of ultraviolet radiation, and fragile ecosystems.
Therefore, most farmers pursue single-season crops, while double-season crops can only be achieved in parts of Ladakh, where the altitude is 3,000 meters below average sea level.
Due to the lack of locally grown vegetables, they need to be obtained from outside the region by trucks from Manali (480 km) and Srinagar (420 km) and cargo planes from Delhi or Chandigarh. Sometimes the freight is as high as per kilogram. 110 rupees.
Winter prices have soared so high that in 2019 the Leh district government had to artificially fix the retail prices of fresh vegetables, such as tomatoes (110 rupees/kg), okra (130 rupees/kg), and cauliflower (110 rupees/kg) And spinach (110 rupees/kg), to name a few. In fact, according to a market survey organized in February 2019, it was found that in winter, the price of fresh vegetables in Leh was almost three times that of Delhi.
In order to address this serious concern of the Ladakh people, researchers from the National Defense High Altitude Research Institute (DIHAR) led by senior scientist Dr. Tsering Stobdan developed a new type of Ladakh greenhouse for local farmers, the passive solar greenhouse.
“We studied the advantages and disadvantages of traditional greenhouses that are widely used in Ladakh. Therefore, four major changes were made. We replaced polyethylene panels with three-layer polycarbonate panels. This resulted in a 7-8 night temperature increase in winter. Celsius, because polycarbonate has better insulation properties. Secondly, unbaked mud bricks are replaced by stone walls, because stone walls have a stronger heat absorption capacity. The heat absorbed during the day is released back to the greenhouse at night. Third, We built the greenhouse three feet below ground level. Therefore, geothermal heat helps keep the greenhouse warm in winter. Finally, we standardized the length, height and width of the greenhouse,” Dr. Stobdan said in an interview with The Better India.
Three different standardized Ladakh greenhouse models include: 1) Commercial: 90x27x9 feet (length x width x height)-approximately cost: 950,000 rupees 2) Medium: 60x24x8.5 feet-approximately cost: 500,000 rupees 3 ) Domestic: 32x18x8 feet-Approximate cost: Rs 300,000
"It is generally believed that the smaller the greenhouse, the better the thermal insulation. However, we found that the situation is just the opposite. The easy-to-operate ventilators in these newly designed and developed greenhouses can easily adjust the temperature in the summer. In the Ladakh greenhouse, the summer The highest temperature recorded was 45 degrees Celsius. The lowest temperature recorded during the winter peak was 1 degrees Celsius. This is why tomatoes grow in the greenhouse. In addition, it is easy to operate. There is no electronic equipment that farmers must use. It is completely passive. Solar greenhouse," Dr. Stobdan explained.
"DIHAR developed this technology, but they have transferred it to the Ladakh Ministry of Agriculture. The department is installing Ladakh greenhouses. We are providing farmers with 75% subsidies for the construction of this greenhouse. So far, we About 100 such greenhouses have been installed for farmers in Ladakh, including medium-sized greenhouses and for household use," said Tashi Tsetan, Chief Agricultural Officer of Ladakh (Federal Territory).
“During the installation process, the farmer’s job is only to build the walls. The department must provide cladding materials (polycarbonate panels), frames, doors and windows, ventilation equipment, etc.,” Tsetan added.
Nevertheless, this is not the first greenhouse version to appear in Ladakh. The first such greenhouse (greenhouse) in Ladakh was established in DIHAR in 1964. The laboratory was formerly an on-site research laboratory for growing vegetables in winter. When this was not feasible due to logistics and high costs, they conceived a low-cost passive solar greenhouse in the late 1960s, in which vegetables were ground in ditches covered with polyethylene plates to prevent crops from being long and harsh. Freeze in winter.
Given that there are no retaining walls and openings above the ground, the product becomes a victim of stray animals. To make matters worse, the adoption rate of such greenhouses is very low. To solve this problem, the first version of the Ladaki greenhouse was designed with three sides (north, east, and west) mud brick walls, a polyethylene covering on the south and a roof on the north wall. This innovation is popular because of its stronger thermal insulation capabilities, allowing farmers in Ladakh to grow leafy vegetables such as lettuce, spinach and coriander in winter.
Over the years, other institutions and organizations, such as the French non-profit organization GERES (Groupe Energies Renouvelables, Environment et Solidarités), Ladakh Environment and Health Organization (LEHO), Ladakh Renewable Energy Development Agency (LREDA) and Sher-e -Kashmir Institute of Agricultural Science and Technology (SKUAST-K) of Kashmir University modified the original Ladakh greenhouse model.
However, other problems arose during the first iteration of the Ladakhi greenhouse. Certain vegetables, such as tomatoes, peppers, broccoli, cabbage, squash, and broccoli, cannot grow during the winter months due to the low temperature at night in the greenhouse. During the summer months, excessive heat is generated in the greenhouse, and the internal temperature rises to as high as 64 degrees Celsius. In summer, farmers either remove the cladding material or do not use the greenhouse at all.
In addition, due to high wind speeds, heavy snow and other extreme conditions, the life span of the polyethylene panels used in the greenhouse will not exceed five years, requiring replacement or constant maintenance. Finally, these greenhouses will not last more than 10 years.
"We started researching this greenhouse in 2014. It took us three years to develop the first functional prototype. Our standard for a functional greenhouse is to grow tomatoes, which is a crop that is highly sensitive to temperature in winter and does not require any external Heat source/power source. In December 2017, we planted tomatoes in the greenhouse for the first time. Then we further studied the new design in winter and summer to grow various vegetables in Leh Ladakh. Our successful experiments led to the design of different sizes Improved greenhouses to meet different farmers’ needs based on the availability of land and resources,” said Dr. Stobdan.
"With the support of the National Defense Research and Development Organization (DRDO), I installed the Ladakh greenhouse in October 2019. This is the third winter I have used it. Before installing this greenhouse, I have installed two Smaller greenhouses covered with polyethylene panels. The problem with these old greenhouses is that they will freeze in them after November. Last winter, I planted cauliflower, cabbage, spinach, methamphetamine, radishes, tomatoes, mustard and coriander. After planting these crops in October, I harvested spinach by December. Cauliflower and the rest, I harvested in January,” said Tashi Tondup Angyal, a 56-year-old farmer from Thiksey who was one of the first adopters of medium-sized greenhouses .
According to a document written by nine researchers chaired by DIHAR in 2019, some of the salient features of the new and improved Ladakh greenhouse include the east, west and north walls built with stone and cement, which they believe requires Minimal maintenance. "The wall on the north side of [the] in the greenhouse is used to fix shelves that can be used for different purposes. The external mud brick wall with insulation between the two walls was also studied," the document explains (no link, source shared with me) .
The second element of the new Ladakh greenhouse is the use of "transparent UV-stabilized three-layer polycarbonate panels to cover the southern side of the greenhouse", which they believe "has better thermal insulation capabilities" and "maintain acceptable even afterwards The transparency of Ladakh has been exposed to the harsh climatic conditions of Ladakh for 20 years.”
Another change in the early iterations of the old passive solar greenhouse was the use of a sloping (north-facing) polyurethane foam (PUF) roof, which was durable, "has better thermal insulation compared to traditional wooden roofs" and "does not allow growth" Mold and fungus", this is the main problem of traditional Ladakh greenhouses with wooden roofs.
In addition to using PUF, another option is to use a rust-proof pre-coated "GI board, covered with a layer of hay and soil as an insulating material, which is also used for the roof." Then, there are metal or polycarbonate doors on Toi, requiring little maintenance and manual but easy-to-operate metal frame ventilators.
Even in December and January, the temperature in these greenhouses is still above freezing. With a shelf life of up to 25 years, farmers can now grow crops year-round.
"During the winter months, a variety of crops have been successfully grown in the greenhouse-cauliflower, cabbage, broccoli, knol-khol, tomatoes, and even mushrooms. In a medium-sized greenhouse, a greenhouse can obtain up to 325 kg Cauliflower; 398 kg cabbage/greenhouse; and 231 kg knol-khol/Leh greenhouse. These crops cannot grow well in traditional greenhouses. In winter, various crops can be grown, otherwise it is impossible in traditional greenhouses. In summer For a few months, crops such as cucumbers are usually harvested in the open land from August. However, when planted in this greenhouse, the harvest is advanced in June, and we enjoy a higher crop yield, 4.5 kg per plant, and 1.6 kg per plant in the open field-crop productivity has been increased by 3 times," said Dr. Stobdan.
“In the winter of last year, considering the vegetables we consume internally, we earned about 75,000 rupees from all the crops grown in the Ladakh greenhouse. In the summer, leafy vegetables such as coriander, spinach and radishes do not grow well. Instead, we grow tomatoes, okra, peppers, eggplants, peppers, etc. Since we started using this greenhouse, I have earned about 175,000 rupees from all the crops grown in it, excluding the items we consume internally. Thanks With this greenhouse, my agricultural income has increased. Now, we can easily grow vegetables in a greenhouse using polycarbonate panels during the peak winter season. In summer, cauliflower sells for 50 rupees per barrel, but in winter (1 Month), our selling price is about 110 rupees per kilo,” Tondup claimed.
But even without such financial assistance, Dr. Stobdan believes that farmers can achieve a balance of income and expenditure on greenhouse investment within six years.
"Our goal is to ensure that locals can get green vegetables during the peak winter season. We have seen in these greenhouses that when the outdoor temperature is -30 degrees Celsius, the indoor temperature is 10 degrees Celsius. Except for farmers, entrepreneurs and others who can't find them in winter Residents who come to work can also earn a good income by growing and selling these marketable vegetables in winter. We even made a crop calendar for farmers to help them understand the crops they can grow in the greenhouse throughout the year. In addition to installation , We also provided them with some training on which crops they can grow in spring, summer and winter," Tsetan said.
In the long term, the goal is to reduce dependence on fresh vegetables outside the region in summer and winter. To this end, the Ladakh UT government aims to build 1,000 greenhouses in Ladakh within the next two years, including Leh and Kargil districts.
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