Construction of a Polyhouse
The polyhouses are
constructed with the help of ultraviolet plastic sheets, so that they may last for more
than 5 years. The structure is covered with 1501 m thick plastic sheet. The structure is
prepared with the bamboos or iron pipes. Iron pipe structure is costly but more durable
than bamboo.
Generally the
length of the polyhouse is 25-30 feet and width 4-5 feet. The direction of polyhouse is
always East to West, so that the maximum sunshine is available. The house should not be
constructed in shade. The size of polyhouse may differ depending on the necessity. The
polyhouses are kept cold or hot depending upon the season.
Use of
Polyhouses:
From the point of
view of earning more profit only such off-season crops should be grown, which are being
sold at higher prices in the market. Big hotels in cities are mostly in the need of
off-season vegetables and so is the case with some prosperous people in big cities. In
such areas and also in the hill and remote regions where fresh vegetables are required
regularly for meeting out the requirements of security forces, the construction of
polyhouses is more lucrative and is a must.
The crops grown
under the polyhouse are safe from unfavourable environment and hailstorm, heavy rains or
scorching sunshine, etc. Crops of the polyhouse can be saved from birds and other wild
animals. The humidity of polyhouse is not adversely affected by evaporation resulting in
less requirement of water. In limited area of polyhouse, insects and pests control is also
easy and less expensive.
By adopting the
modern technology of polyhouse, the difference in the demand and supply of off-season
vegetables and fruits etc. can be minimised. This facilitates in maintaining the quality
of the product also.
Heating of
Polyhouse
Heating is required
in winter season. Generally, the solar energy is sufficient to maintain inner temperature
of polyhouse but some times more temperature is required to be supplied to some crops. For
this few methods are as follows:
- Constructing a tunnel below the
earth of poly house.
- Covering the northern wall of the
house by jute clothing.
- Covering whole of the polyhouse with
jute cloth during night
- Fitting solar energy driven device
in polyhouse.
Cooling of
Polyhouse
In summer season,
when ambient temperature rises above 400C during day time the cooling of
polyhouse is required by the following measures, not only the temperature but also
relative humidity of polyhouse can also be kept within limit.
- Removing the internal air or
polyhouse out of it in a natural manner.
- Changing the internal air into
external air by putting the fan on.
- Installation of cooler on eastern or
Western Wall not only keeps temperature low but maintains proper humidity also.
- Running water-misting machine can
control the temperature of the polyhouse.
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