Vegetable greenhouses will only really play the "greenhouse" effect by covering the greenhouse film. In actual production, many rural households have misunderstandings in the selection and coverage of greenhouse films.
In general, vegetable greenhouse films are divided into two parts, one is a roofing film, and the other is a ventilation film. The former recommends the purchase of high-temperature composite films of polyvinyl chloride or ethylene-vinyl acetate, which have high light transmittance, no drop-mist, and long-life properties. The latter suggests the use of polyethylene-based films. Many peasant households can use the polyvinyl chloride film as a shed film. Among them, the length of a vegetable greenhouse for a vegetable farmer is 100 meters. Because of the high stretchability of the polyvinyl chloride film, he used only 90 meters long and 2.2 meters wide. As a result, originally at the outlet, the roofing film overlapped with the shed film by 30 cm to ensure the “wind-retentive†effect. However, as time passes, the stretchable PVC film “shrinksâ€, resulting in closure of the wind. Not strictly. If it is winter at night, the wind is not tight, and it is easy to cause freezing damage to vegetables. Therefore, do not use PVC film as a ventilation film.
As for the film rope, its main role is to "press" the film, rather than destroy the film. Many of the filming ropes of the farmers' sheds are tilted from top to bottom instead of straight up and down. Due to the inclined pull of the film rope, it straddles the (big bamboo pole or steel pipe) arch rod. After a long time, the straw string is pulled back and forth. The film rope rubs back and forth with the film, resulting in damage to the film. Seriously affect the insulation effect of the film.
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