According to the determination of the snow pressure by the relevant authorities, if the thickness of the snow reaches 10 cm, the pressure on the shed of each square metre will be 1.25 kilograms, and the greenhouse with a span of 8 meters and a length of 50 meters will bear an area of ​​350 m2. The weight of snow pressure on the surface is 4,375 kg. In addition, the weight of each grass pressed on the awning is 25 kg, and 50 grass rakes are 1,250 kg. A 10 cm thick snow pressure plus 50 grasshoppers weighs 5625 kg. Such a large pressure is unbearable to the general skeleton, not to mention the "weak and fragile" shelters? Therefore, snow days must be especially vigilant and clear the snow on the shed at any time. In addition, some columns with large spans, few pillars, and poorly-firm skeletons should be erected in a timely manner to prevent problems.
First, snow covered grass cover
Snowfall days generally have thicker clouds, slower ground cooling, lower winds, and lower temperatures. In order to reduce the troubles of removing snow, soaking the grass and soaking the grass and reducing the pressure on the roof of the grass, the grass can be rolled up during the snowfall. As long as the snow is not too large, the snow can accumulate on the surface of the greenhouse. The snow has insulation effect, like a layer of grass cover. After the snow stopped, the snow on the surface of the film was promptly removed and the grass was covered at night. Snow accumulation at a height of about one meter around the front edge of greenhouses and sheds can be eliminated, because these snow cover will not cause pressure on the shed body skeleton, and the thick snow layer can also play a role in insulation.
Second, after the snow suddenly clear back
In the snow, due to the lack of direct light, the temperature in the greenhouse is low, especially when the snow continues to grow. For fruits and vegetables, when the local temperature is below 10°C, the growth and absorption of roots basically cease. And the old root's absorption function is rapidly declining, and new roots are hard to happen. The longer the duration of overcast snow days, the greater the damage. When the weather is clear after the snowfall, if the room temperature is immediately lifted, the light in the leaves will increase and the plants will transpire to a large extent. However, the roots will be unable to meet the transpiration of the leaves if the water absorption capacity is very weak. If measures are not taken in time, it will make The leaves form a permanent withering that is difficult to recover and eventually leads to plant death. In order to prevent this from happening, it is imperative not to lift it all at once. It is advisable to take a heuristic approach, that is, to reduce the number of things first, such as to set off 1/4 first. After a certain period of time, if there is no abnormal reaction in the leaves, we can lift some more. All opened. If you find that the leaves appear wilting, you should promptly look back. This unrestrained, recalled multiple recovery adaptation process may take several days. Sometimes, due to the long hours of low temperature in the greenhouse and excessive root deaths, even if it does not help, it is necessary to consider replanting.
Third, the snow after the snow to pay attention to the night insulation
After the snow was clear, the night sky was covered with no clouds, and a large amount of ground heat was dissipated and quickly cooled. If the temperature of the greenhouse itself is poor, the temperature will rapidly decrease with the decrease of the outside temperature, and even a low temperature near 0°C will occur, causing the crop to suffer cold damage and even freeze damage. To prevent the low temperature approach: put down grasshoppers before sunset to store as much heat as possible; increase the number of cover layers to reduce heat loss; temporarily warm up to disperse cold air.
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