Type cost
This kind of shed has been popularized and applied for many years. It is a steel shed mainly made of galvanized thin-walled steel pipes, with a diameter of 22 mm, a thickness of 1.2mm, a shed width of 6 meters, a shed roof height of 2.2-2.5 meters, a shoulder height of 1.2 meters, a land utilization rate of 80%, a service life of more than 10 years and a cost per square meter. Suitable for planting vegetables, flowers, etc. However, the disadvantages are small shed width, low operation and management efficiency and weak heat preservation in winter.
It is a widely used type. Generally, the shed is 5-6 meters wide, 2-3.2 meters high at the top, 1- 1.2 meters high at the sides, and the arch-pole spacing is1-1. The advantages are low cost, convenient material acquisition and easy construction, and the cost per mu is about 3,000 yuan (including film). The disadvantages are that there are many columns in the greenhouse, high shading rate, inconvenient operation, short service life and poor snow resistance. Among them, there is a shed commonly known as "ground rolling dragon", with a span of 4-6 meters and a top height of shoulder height. Compared with ordinary bamboo vegetable greenhouses, it saves cost and is suitable for crawling crops. Watermelon cultivation in greenhouse is widely used.
The shed structure is the same as the simple bamboo shed, and steel pipes and bamboo poles are used as arch poles at intervals, which has the advantages of saving steel, reducing cost and convenient operation, and has a certain application area; Performance and cost are between steel frame greenhouse and bamboo frame greenhouse.
Increase the height and width of the shed, increase the height and width of the ventilation window beside the shed, increase the space in the shed, improve the management efficiency and thermal insulation in winter, and improve the land utilization rate. Galvanized pipes with a diameter of 28-32mm and a thickness of 1.5mm are used in the shed: the roof height is 3.2-3.5m, the shoulder height is 1.8m, and the space in the shed is large, which is suitable for planting tall lianas. However, the construction cost of this vegetable greenhouse has greatly increased, with a cost of about 20-45 yuan per square meter and 0/.5-30,000 yuan per mu, which is mainly suitable for agricultural demonstration parks and vegetable farmers with certain economic strength.
1. The structure of common multi-span greenhouse is similar to that of steel frame multi-span greenhouse, with large space and high land utilization rate, but the cost is much reduced, ranging from 50- 100 yuan per square meter.
2. Introduction of covering materials for vegetable greenhouses
Vegetable farmers should choose suitable covering materials for vegetable greenhouses according to their own production needs.
(1) ordinary membrane. Using polyethylene or polyvinyl chloride as raw materials, the thickness of greenhouse film is 0. 1 mm, which is colorless and transparent; The service life is about half a year.
(2) Multifunctional long-life membrane. It is made by adding proper amount of anti-aging materials and surfactants in the process of polyethylene blow molding. The width is 7.5m, the thickness is 0.06mm, the service life is 1 times longer than that of ordinary film, and the greenhouse temperature at night is1-2℃ higher than that of other materials; The film is not easy to drip, with good covering effect, low cost and high benefit.
(3) grass cover and grass fan. It is woven from straw and has good heat insulation performance. It is a kind of heat preservation material at night.
(4) Polyethylene high foaming film. White plastic film with many bubbles, width of 1 m, thickness of 0.4-0.5 cm, light weight, rollable, and thermal insulation similar to grass quilt.
(5) Non-woven fabrics. A kind of polyester filament, nonwoven cloth. It is divided into black and white, with different densities and thicknesses. Besides heat preservation, it can also be used as a sunshade net.
(6) sunshade net. Plastic woven screen. Commonly used are black and silver gray, and there are several density specifications with different shading rates. It is mainly used for sun protection and rain protection in summer, and can also be used as a heat preservation cover in winter.
3. Determination of vegetable greenhouse orientation
It should be built on a plot with low groundwater level, sufficient water source, convenient irrigation and drainage, loose and fertile soil and no pollution; Generally, the seat direction is required to be north-south, and the air outlet is located on the east and west sides.
The advantages of this are:
(1) is beneficial to reduce the humidity in the shed;
(2) Reduce the mutual shading between cultivated crops and tall crops in the shed, and make them receive light evenly;
(3) It avoids the rapid cooling and the attack of the north wind when the greenhouse is ventilated (cooled) in winter, and at the same time increases the ventilation volume.
The development of greenhouse vegetable planting technology can be said to be a trend. With the improvement of people's living standards, the demand for diversified vegetables will further increase. Vegetable greenhouse can make up for the seasonal shortage of some vegetables and will undoubtedly play an important role in vegetable production in the future.