Poly House

INTRODUCTION Polyhouse is a protective shade made up of  polythene used for growing high value

agricultural

products.It

is

semi-circular,

square

or

elongated

in

shape. Temperature, humidity, ventilation of air are controlled by the equipments fixed in the polyhouse. Crops grown in the polyhouse are protected from intense heat, bright sunlight, strong winds, hailstones and cold waves. Polyhouses are used in floriculture and nurseries. Besides from this polyhouses are also used for horticulture, though the primary and best is floriculture when considering the investment. A prime example would be the ability to grow vegetables/fruits when its usually off season. In a place like India, the inability to grow tomato during rainy season allows its price to soar during the monsoon. This is spotted as an ideal time to grow tomato in poly houses. This is because the poly house is designed in such a way to provide ideal climate to the crop of your choice. Every factor influencing a crop can be controlled in a poly house. For eg. If you have your poly house in a tropical zone, temperatures are prone to soar above all normal levels. In such cases, foggers/misters are used to reduce the temperature. This does not enhance the humidity levels in the poly house as the evaporated droplets are almost immediately ventilated to open air. High tech poly houses even have heating systems as well as soil heating systems to purify the soil of  unwanted viruses, bacteria etc.The recent Indo-Israel colaboration at Gharunda, near karnal is excellent example of the Polyhouse farming taking place in a developing country. POLY HOUSE

The crops grown in open field are exposed to vivid environmental conditions, attack  of insects and pests, whereas the polyhouse provides a more stable environment. Polyhouse can be divided in to two types-

a) Naturally ventilated polyhouse

These polyhouse do not have any environmental control system except for the provision of adequate ventilation and fogger system to prevent basically the damage from weather aberrations and other natural agents.. b) Environmental controlled polyhouse

This type of polyhouse helps to extend the growing season or permits off-season production by way of controlling light, temperature, humidity, carbon-dioxide level and nature of root medium.

Other type isSolar Polyhouse Drier: Field Research Laboratory (DRDO), Leh has designed and

developed a low cost non-conventional zero energy based solar polyhouse drier for scientific and hygienic dehydration of surplus fruits and vegetables like apricot, apple, cauliflower, cabbage, tomato, etc. when there is a glut in the market and to facilitate its availability during the snow bound winter. The drier works on the principle of  greenhouse effect where it traps the solar radiation and maintains the temperature inside between 55-69o C. Provision has also been made for removal of hot and moist

air from the chamber. It reduces drying period by 40  –  50 % as compared to sun drying. Hobby Polyhouse

We offer a wide range of hobby polyhouses which are compact,easy to assemble,light weight hence can be moved easily. These are available in elegent and attractive designs and different shapes & sizes. Hobby polyhouse gives controlled environment to the plants.

Features 

durable, sturdy, tubular steel structure



compact and easy to assemble, no tools required



removable cover with zipped front panel for easy access and ventilation



light weight hence can be moved easily



ideal for any sheltered place including terrace, veranda, court yard, balconies etc.



ideal for seed propagation, plant growing and display



available in elegant and attractive designs with different shapes & size.

Shade house

Shadehouses are used for the production of plants in warm climates or during summer

months. Nurserymen use these structures for the growth of hydrangeas and azaleas during the summer months. Apart from nursery, flowers and foliages which require shade can also be grown in shadehouses. E.g. Orchids, These shade structures make excellent holding areas for field-grown stock while it is being prepared for shipping to retail outlets. Shadehouses are most often constructed as a pole-supported structure and covered with either lath (lathhouses) or polypropylene shade fabric. Polypropylene shadenets with various percentages of ventilations are used. Black, green, and white coloured nets are used, while black colours are the most preferred as it retains heat outside. ORIENTATION OF GREENHOUSE / POLYHOUSE

The design of greenhouse should be based upon sound scientific principles which facilitates controlled environment for the plant growth. Controlled environment plant production systems are used widely throughout the world to produce plant materials and products at a time or place, or of a quality that can not be obtained outdoors. Controlled environment agriculture requires far more capital investment per unit area than field agriculture and thus must essentially be correspondingly more intensive to  justify investment costs. The greenhouse is a structure covered with a transparent material for admitting natural light for plant growth. The main components of  greenhouse like structure, covering/glazing and temperature control systems need proper design for healthy growth of plants. Under Indian conditions, Quonset type, multispan greenhouse is most suitable, because of its low cost and ease of fabrication. Ultra violet resistant low density polyethylene (UVLDPE) single film cladding of 200 micron thickness is sufficient for Naturally Ventilated ( NV) greenhouse and fan and pad (FP) greenhouses. This should be fully tightened by stretching on the structure to avoid fluter and tearing. It should not be nailed or screwed to the structure as it gives the chance for tearing. The T-Lock  of L-Lock should be used for fastening the sheet at structure, as this does not tear the sheet and sheet replacement is easy.

Design

The structure has to carry the following loads and is to be designed accordingly. a) Dead load: weight of all permanent construction, cladding, heating and cooling

equipment, water pipes and all fixed service equipments to the frame. b) Live load: weights superimposed by use (include hanging baskets, shelves and

persons working on roof). The greenhouse has to be designed for a maximum of 15 kg per square meter live load. Each member of roof should be capable of supporting 45 kg of concentrated load when applied at its centre. c) Wind load: The structure should be able to withstand winds of 110 kilometer per

hour and at least 50 kg per square meter of wind pressure. d) Snow load: These are to be taken as per the average snowfall of the location

The greenhouse should be able to take dead load plus live load or dead load plus wind load plus half the live load. The greenhouses are to be fabricated out of Galvanized Iron Pipes. The foundation can be 60cmx60cmx60cm or 30 cm diameter and one meter depth in PCC of 1:4:8 ratio. The vertical poles should also be covered to the height of 60 c m by PCC with a thickness of 5cm. This avoids the rusting of the poles. Orientation

Orientation of the greenhouse is a compromise for wind direction, latitude of location and type of temperature control. Single greenhouses with latitude above 40°N should have ridge running east to west to allow low angle light to enter from side rather than ends. Below 40°N the ridge of single greenhouses should be oriented from north to south, since the angle of sun is much higher. This orientation permits the movement of  shadow of the gutter across the green house. The location and orientation of the greenhouse should avoid falling of shadow on the adjacent greenhouses. To avoid the shading effect from one green house to another greenhouse these should be oriented East to West. However, the wind direction and latitude are also to be considered.

Wind effects

If the greenhouse is naturally ventilated, the advantage of natural wind direction has to be taken to the maximum possible. The maximum dimension (length) of greenhouse should be perpendicular to the wind direction especially in summer. For fan and pad greenhouse the natural wind direction should be same as the air blown by fan. Size of the greenhouse

The dimension of NAV GH should not be more than 50m x 50m. Bigger the greenhouse, more will be the temperature build up due to poor ventilation. The length of evaporatively cooled greenhouse should not be more than 60m. Spacing between greenhouses

The spacing between naturally ventilated green house should be 10 to 15 m so that the exhaust from one greenhouse should not enter the adjacent greenhouse. Height of greenhouse

The maximum height can be up to 5m for 50m x 50m green house and this can be reduced as per the reduced size of the green house. Higher is the greenhouse more is the wind load for structure and glazing. The side ventilation can be of 2 m width and roof ventilation is 1m in width. Structural design

The greenhouses are to be designed for necessary safety, serviceability, general structural integrity and suitability. The structure should be able to take all the necessary dead, live, wind and snow loads. The foundation, columns and trusses are to be designed accordingly. The greenhouse structures are to be designed to take up the loads as per design loads prescribed by the National Greenhouse Manufactures Association (NGMA of USA) standards  – 1994. 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.

MATERIAL USED

1. Polyhouse is the construction under controlled environment. 2. The polyhouse can be made of transparent, tight, cheap and flexible polythene. 3. In these houses vegetables and other crops can be grown in any season of the year depending upon their requirement, because temperature and humidity can easily be controlled in Polyhouses. 4. Polythene presents the thermal radiation, which increases the temperature and energy and thus helps in the process of photosynthesis. It is well established that for the production of energy vegetable, fruits and flower crop, the polyhouses are constructed with the help of ultraviolet plastic sheets, so that they may last for more than 5 years.

5. The structure is covered with 1501-micron thick plastic sheet. The structure is prepared with the bamboos or iron pipes. 6. Iron pipe structure is costly but more durable than bamboo. Roof of Polyhouse

In case of construction of polyhouse plastic film, nylon, acralyc, vinyl, polycarbonate and polyethylene film can be used for the roof purpose. At present among the available polyfilm, use of I.P.C.L Baroda (Gujarat) made 200 microns or 800 gauge thickness ultraviolet protective film is considered as a better for polyhouse use. The framework of polyhouse should be made of G.I. pipe. For the construction of  polyhouse following equipments are required: 1. Framework 

Framework 



Wooden plank 



G.I. wire

2. Covering 

Plastic sheet



Nylon net 80 mesh/white

3. Cold storage chain 

Cold storage structure



Exhaust fan



Fan (for circulation of air)



Aluminium network 

4. Water management structure 

Automatic filtration



Sprinkler system



Drip irrigation system



Mechanism providing fertilizers along with water

5. Equipments Automatic operated equipment such as: 

pH meter,



water meter



Electric conductivity meter

6. Electric equipments 7. Installment 

Framework, film Installing equipments

8. Building structure 

Bore well,



Electric pump

ECONOMIC SIZE

1. Generally the length of the polyhouse is 25-30 feet and width 4-5 feet. 2. The direction of poly house is always East to West, so that the maximum sunshine is available. 3. The house should bot be constructed in shade. 4. The size of polyhouse may differ depending on the necessity. 5. The poly houses are kept cold or hot depending upon the season. In case of permanent polyhouse structure steel and fiber made glass are galvanised hallow pipe-having glass or transparent polythene sheet structure is needed. For small

farmers they can build up the polyhouse they require bamboo structure on which polythene sheet is used for cover purpose. For irrigation facility sprinkler irrigation unit is needed, while for controlling the air temperature ventilators are required. In case of polyhouse designing and construction for an acre of area following capital investment is required. 1. Framework Framework  Wooden plank  G.I. wire

15,00,000 25,00,000 35,000

2. Covering Plastic sheet Nylon net 80 mesh/white

28,00,000 12,00,000

3. Cold storage chain

8,00,000 4,20,000 2,03,000 1,00,000

Cold storage structure Exhaust fan Fan (for circulation of air) Aluminium network  4. Water management structure Automatic filtration Sprinkler system Drip irrigation system Mechanism providing fertilizers along with water 5. Equipments

5,00,000 25,000 25,000 2,62,000

10,00,000 30,000

Automatic operated equipment e.g. pH meter, water meter Electric conductivity meter 6. Electric work

7. Installment

15,00,000 3,01,000 25,00,000

Framework, film Installing equipments 8. Building structure Land development Related to water management Bore well, electric pump Construction expenses

1,56,000 60,000 2,75,000 5,33,000

9. Other miscellaneous work

1,27,000

Total

83,07,000

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: i.

Constructing a tunnel below the earth of poly house.

ii.

Covering the northern wall of the house by jute clothing.

iii.

Covering whole of the polyhouse with jute cloth during night

iv.

Fitting solar energy driven device in polyhouse.

Cooling of Polyhouse 0

In summer season, when ambient temperature rises above 40 C 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. i.

Removing the internal air or polyhouse out of it in a natural manner.

ii.

Changing the internal air into external air by putting the fan on.

iii.

Installation of cooler on eastern or Western Wall not only keeps temperature low but maintains proper humidity also.

iv.

Running water-misting machine can control the temperature of the polyhouse.

POLYHOUSE AUTOMATION

Polyhouses have reached a high level of automation. Some commercial polyhouse systems automatically monitor and control several environmental parameters including inside air temperature, relativity humidity, soil pH value and electrical conductivity. A farmer can set reference values and then the system maintains these values automatically. However such systems are very expensive. A low- to mediumcost polyhouse could cost between Rs. 125 to Rs. 500 per square meter in India, whereas a high-cost, fully-automated polyhouse costs Rs. 2,000 per square meter. Most Indian farmers cannot afford such high costs. Moreover, automation is not a major problem in Indian polyhouses, since labour is not very expensive. On the other hand, lack of

expertise is a major problem for Indian farmers and it would get

enhanced if a fully automated system is to be installed.