Advantage of polyhouse Farming
- High production per unit are of land
- Easy control of pest and diseases
- Prolonged production period
- Efficient water utilization
- Low cost Labor
- High quality of crop production
- Timely crop production
- Saving on crop protection chemicals
- Less exposure to
2) Partial climate controlled polyhouse.
3) Fully controlled polyhouse
4)Plastic low tunnels
- Low initial investment.
- Constructed with locally available material such as bamboo ,timber etc.
- No specific control devices for regulating environmental parameters inside the polyhouse.
- Suitable during cold weather,especially in hilly areas
- low tech polyhouse
The low tech polyhouse structure which is constructed using locally available materials.Bamboo,Timber,polythene sheets etc.this materials are uses to make low cost polyhouse.the protective ultra violet (u.v) films used as a cladding material.No specific control device are provided for temperature controlling or regulating environment parameters as in case of high tech polyhouse. But simple technique like increasing or decreasing humidity,temperature are adopted.Also light intensity can be reduced by putting nets or covering the sheets with jute fabric.
The low cost polyhouse is good for climatic zone where the temperature can be reduce in summer season by the removing the side wall.
Greenhouse users prefers to have manually or semiautomatic control arrangement owing to minimum investment. This type of greenhouse is constructed using galvanized iron (G.I) pipes. The canopy cover is attached with structure with the help of screws. Whole structure is firmly fixed with the ground to withstand the disturbance against wind. Exhaust fans with thermostat are provided to control the temperature. Evaporate cooling pads and misting arrangements are also made to maintain a favorable humidity inside the greenhouse. As these system are semi-automatic, hence, require a lot of attention and care, and it is very difficult and cumbersome to maintain uniform environment throughout the cropping period. These greenhouses are suitable for dry and composite climatic zones.
To overcome some of the difficulties in medium-tech greenhouse, a hi-tech greenhouse where the entire device, controlling the environment parameters, are supported to function automatically.
Polyhouse or green house are constructed helps of ultra violet plastic sheet.Sheets are usually of 1501-micron thick plastic sheet.For this polythene sheet the temperature and humidity can easily be controlled in polyhouse as they prevent the thermal radiation from escaping which increase the temperature and energy .The temperature and energy help in the process of photosynthesis .After The polyhouse sheet need to be changed after around every 5 years.
Heating is usually required in winter season. Generally the solar energy is sufficient to maintain inner temperature of polyhouse but when this is insufficient, via media like construction of a tunnel below the earth of polyhouse, covering the northern wall of the house by jute clothing, covering whole of the polyhouse with jute cloth during night and installing solar heating systems can be considered.
In summer season when ambient temperature rises above 400C during daytime, the cooling of polyhouse is required. This is done by providing adequate ventilation and removing the internal air of polyhouse out of it in a natural manner or by installing high power fans which need to be switched on at regular intervals. Installation of
cooler on eastern or Western Wall can also be done to keep the temperature low and maintain proper humidity. Alternatively Water-misting mechanism can be installed.
Certain plants are damaged due to very high light intensity during summer. Shading reduces light intensity and cools the micro climate inside the greenhouse. Shade paints (lime or Redusol or Vari clear), agro-shade nets or retractable thermal screens are generally used and operated manually or through automatic devices.
Roof: transparent cover of a green house.
Gable: transparent wall of a green house
Cladding material: transparent material mounted on the walls and roof of a green house.
Rigid cladding material: cladding material with such a degree of rigidity that any deformation of the structure may result in damage to it. Ex. Glass
Flexible cladding material: cladding material with such a degree of flexibility that any deformation of the structure will not result in damage to it. Ex. Plastic film
Gutter: collects and drains rain water and snow which is place at an elevated level between two spans.
Column: vertical structure member carrying the green house structure
Purling: a member who connects cladding supporting bars to the columns
Ridge: highest horizontal section in top of the roof
Girder: horizontal structure member, connecting columns on gutter height
Bracing: To support the structure against wind
Arches: Member supporting covering materials
Foundation pipe: Connection between the structure and ground
Span width: Center to center distance of the gutters in multispan houses
Green house length: dimension of the green house in the direction of gable
Green house width: dimension of the green house in the direction of the gutter
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