Scientific research

Greenhouse in the ground (greenhouse thermos)

Author: Knowledge Management in CACILM Phase II, ICARDA.

Definition of technology:

Using the constant temperature of the earth at a certain depth inside the greenhouses allows saving costs for heating during cold seasons, facilitates maintenance, and creates a more stable climate.

Brief summary of technology:

The technology of greenhouse-thermos is known since long. In Tsarist Russia, deep greenhouses allowed harvesting pineapples that merchants exported to Europe for sale. However, due to some reasons the practice of construction of these greenhouses was forgotten.

1. Preparation of the pit The main portion of the greenhouse is set into the ground, so a pit with a depth of at least 2 m must be dug. The length of the underground portion of the greenhouse can vary, but the width should not be more than 5 m. If this size is exceed, the heating and light reflection will be weaker. Underground greenhouses should be oriented from east to west, so that one of the sides face south. In this position, the plants will receive the maximum amount of solar energy.

2. Walls and roof A greenhouse foundation should be built or construction blocks installed along the perimeter of the pit. The foundation is the basis for the walls and frame of the greenhouse. The walls are best constructed from a material with good thermal insulation characteristics, such as thermal blocks. Roof frame is often make from wood, using bars impregnated with antiseptic materials.

The roof structure is usually made straight, gable. Honeycombed polycarbonate, a popular modern material is best suited as the roof cover. The distance between the rafters in the construction is customized accounting for the width of polycarbonate sheets. Coating is obtained with a small number of joints as the sheets are typically produced with a length of 12 m. For a good insulation, the roof is sometimes made with a double polycarbonate layer. Although in this case the transparency is reduced by about 10%, this disadvantage is overcome by excellent thermal insulation characteristics.

3. Warming Inner side of the walls should be covered with a special thermoinsulating film, which will keep the heat inside the greenhouse.

For the purpose of heating, local people use dung heaps placed in the corners of the greenhouse.

The general interior illumination is not lost by burial of the greenhouse into the ground, it may seem strange, but in some cases, light saturation is even higher than that of the classical greenhouses.

Location: Farish district, Jizzakh province.

Area of technology application: 160 m2.

Main land use issues and the main causes of land degradation:

Conventional ground-based greenhouse requires a lot of energy for heating, which is more expensive and harder to heat compared to that of the underground greenhouse.

Main technical features of technology:

Financial savings by growing crops in the ground.

Assessment

Impact of technology

Main advantages:

- saving on energy for heating;

- saving on illumination;

- microclimate in deep-ground greenhouse during winter is favorable for plants, there is an excellent condition for heat-loving plants;

- seedlings strike roots easily;

- greenhouse ensures a stable, high yield all year round.

Main disadvantages:

- excavation work is labor intensive, but investments in greenhouse - thermos are justified.

Acceptance/adoption of technology: The population of Uzbekistan uses this method of growing crops in deep greenhouses in different regions on its own initiative on the basis of traditional experience.

Reference(s): Information provided by the specialists of ICARDA-CAC (Project on Knowledge Management in CACILM II) from personal observations. The information was obtained from the site:

http://www.nazemle.org/hozyaistvo/rasteniyevodstvo/44-zaglublennaya-teplica-termos.html;

http://vasha-teplitsa.ru/karkas/teplica-termos.html

Name of person(s) collected this description: Tatyana Hamzina, Chief specialist on soil reclamation studies and irrigation regime. UZGIP LTD.

Address: 44, Navoi str., Tashkent, Uzbekistan.

Tel.: +998 90 9945654

Email: tatyana_khamzina@mail.ru 

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