In winter, the temperature is low and the shed is relatively closed. How to properly ventilate is particularly important. The technicians have collected various measures and techniques for the sheds in the winter sheds through long-term sheds. I hope to help everyone's daily ventilation management.

The thermometer setting should be reasonable

The important basis for the vegetable farmers to release the wind is to look at the thermometer, and its accuracy is directly related to whether the vegetables are in a suitable environment for growth.

Some farmers have to set the temperature gauge only at the end near the shed door for convenient reading temperature. This is not desirable because the temperature near the shed door is relatively low. If the vent is adjusted according to its display temperature, it will inevitably lead to the shed. The temperature is high, which affects the normal growth of vegetables.

Therefore, it is recommended that the vegetable farmers uniformly set three thermometers in the east-west direction of the shed, and then take the average value to reduce the error, and the lower end of the thermometer is placed about 10 cm above the vegetable growth point.

The size of the air outlet should be determined according to the wind direction, position, etc.

Many vegetable farmers have reported that a vegetable in the greenhouse grows poorly, while the vegetables on the other side of the greenhouse grow very well. In particular, some color-changing solanaceous vegetables, such as tomatoes, always appear in the greenhouse. The same greenhouse, the same management method, why the vegetables at the two ends of the greenhouse will grow differently?

Because the wind direction is not considered when the wind is released, the size of the air outlet of the greenhouse is the same, resulting in different temperatures at the two ends of the shed.

When the wind direction is different, the temperature in different places in the shed is different: when there is no wind or slightly northeast wind (or southeast wind), the temperature at the west end of the shed is 2-3 degrees higher than that in the eastern half, and when the wind is large, the east The end is about 2 degrees higher than the west end. When there is northwest wind or southwest wind, the temperature difference between the east and west ends will be above 3 degrees (the west end is high), and the wind is getting bigger and the temperature difference is larger. How to determine the size of the air outlet according to the wind direction?

When the west wind or the west wind is blown, the wind will enter the shed along the air outlet, resulting in a lower temperature in the east of the shed. The vegetable grower can properly close the east air outlet when the wind is released, and the west side of the greenhouse needs to be placed. The air outlet is enlarged to reduce the temperature of the west side of the shed to ensure uniform temperature in the shed. Conversely, when encountering east winds or easterly winds, the same management measures should be adopted. When the southerly wind or the north wind is blown, the air outlets on both sides of the greenhouse can be opened to the same size.

Only according to the difference of wind direction, properly adjust the size of the air outlets at both ends of the greenhouse to ensure the uniform temperature in the shed, in order to promote the simultaneous growth of vegetables.

In addition, in the greenhouse, due to the light absorption of the two gables in the greenhouse, the temperature rise at both ends of the shed is slower, so that the temperature at both ends of the shed is lower than the temperature in the middle of the greenhouse. When the wind is released, the vegetable grower should open the air outlet at the two ends of the greenhouse.

Don't worry, pay attention to step by step

In the winter greenhouse, the greenhouse will not be released for an hour after the quilt is opened in the morning.

Because the temperature in autumn and winter is low, after the grass cover is covered at night, the vegetables in the greenhouse stop photosynthesis, and only a large amount of carbon dioxide is released by respiration. At the same time, the microbial decomposition of organic matter in the soil also releases carbon dioxide, and the amount of carbon dioxide accumulated in the shed rises significantly after overnight. It is much higher than the carbon dioxide content in the outside atmosphere. When the curtains were opened in the early morning, the sun began to shine, and green plants such as vegetables began to use photosynthesis, which required a large amount of carbon dioxide. At this time, the concentration was high, which could give enough raw materials for vegetables and convert them into nourishment after photosynthesis. Stored in vegetables. In the hour before the release of the wind, the organic matter accumulated by the plants through photosynthesis will be several times as usual, which is conducive to the increase of vegetable yield.

After pulling the shed for 1 hour, let the small mouth release the wind for 7-8 minutes, and the width of the vent is generally about 5 cm. Its purpose is to put in carbon dioxide, enhance crop photosynthesis, and remove moisture and harmful gases.

When the temperature of the shed rises to the upper limit of the high temperature required by the crop, the wind is again applied to gradually reduce the temperature to a range suitable for vegetable growth. At noon time (12 o'clock to 14 o'clock), the photosynthesis of crops is in the state of "noon break". In order to reduce their respiratory consumption, the temperature of the shed can be lowered by about 2 degrees as appropriate.

If the vegetables have been infected with diseases such as gray mold and leaf mold, ventilation should be different. After the first release of the air for half an hour, pull the air vents in time so that the shed temperature quickly rises to 30~35 °C for about one hour, and then a second release. The aim is to create environmental conditions that are not conducive to the growth of pathogenic bacteria.

After watering, it should be warmed up before releasing the air.

After the watering of the greenhouse in winter, the temperature in the shed is obviously reduced. If it is ventilated after watering, the temperature in the shed will remain at a low level, and the ground temperature will naturally not rise. When the root system is in a low ground temperature environment for a long time, it is prone to root injury, which leads to its weak ability to absorb fertilizer and water, and the growth and development of vegetables are hindered.

Of course, it is not possible to ventilate for a long time after watering. If the vegetable grower has always closed the vent, the moisture in the shed will not be discharged, and when the temperature is lowered at night, more dew will form, which is beneficial to the infection of pathogenic bacteria. Moreover, the ventilating port is not opened, and the carbon dioxide in the shed is lacking, the photosynthesis is stagnant, the plant is lack of nutrition, and the plant resistance is reduced, which is not conducive to the normal growth of vegetables.

When the temperature of the shed is low, premature venting will increase the humidity in the shed. Therefore, it is usually necessary to warm the ventilating air before releasing the air. Only when the shed temperature is raised can the humidity be lowered. It is difficult to get out of the air without first warming up.

The correct way: after watering in winter, you should choose a sunny day to pull the shed 30 °C or more, open the small mouth to release the air for half an hour, then close the vent, keep the temperature in the shed has been around 30 °C.

After half an hour, open the small mouth ventilation until about 3 pm, the temperature of the greenhouse is reduced to 23~25 °C, and the vents are closed. When the temperature in the shed is lowered to about 20 °C, open the small mouth and ventilate for about 15 minutes, then cover the grass hoe or keep warm.

Pay attention to the wind on a cloudy day.

When the wind is released on a cloudy day, the wind cannot be released too early to prevent the temperature in the shed from decreasing and affecting the growth of vegetables. It can be selected from 12 noon to 2 pm during the release of the wind. It is advisable to open the air outlet to 6~8cm, and the air release time can be 10~15 minutes, then close the air outlet in time to prevent the temperature in the shed from falling too much.

After 30 minutes, the air is released again for 10~15 minutes, so that after a continuous interval of 2~3 times, a large amount of harmful gas in the shed can be discharged outside the shed, which is also conducive to reducing the humidity in the shed and inhibiting the disease. happened. The cold weather or the windy weather may not be ventilated.

Many vegetable farmers do not release the air for a few days in a cloudy day to ensure the temperature inside the shed, which is extremely unfavorable for the growth of vegetables. The humidity is too high, and various diseases are frequent; in addition, the harmful gas in the shed accumulates too much in the shed, and it is easy to cause gas damage.

In the winter and early spring, when there is even cloudy weather, if the temperature in the shed is allowed (above 16 °C), the air outlet must be opened for ventilation. The purpose of this is to discharge the moisture and harmful gases in the shed outside the shed to avoid gas damage.

Buffer film under the air outlet

The ventilation of the greenhouse in the winter mainly depends on the top air outlet. Many vegetable farmers often have serious physiological diseases due to improper management of the vents. Providing a buffer film under the air outlet not only prevents weeds and dust on the straw curtain from entering the shed, but also affects the photosynthesis of the vegetables on the leaves. More importantly, it can avoid the dry and cold air from the outside when the air is blown. On the vegetables, it causes problems such as suede and poor color change.

The setting of the buffer film is very simple. The vegetable grower can use a mucosal machine to stick a 2-3 cm "cloth bag" on both sides of the buffer film with a width of 2.0-2.5 m, and a steel wire 6-8 meters longer than the shed on the upper side. It is fixed at 30-40 cm south of the vent, and then the wire is fixed on the ground rivet on the outside of the two sides of the shed, and tightened with a tightening machine. Use a wire to fix the steel wire of the buffer film and the steel wire or steel pipe on the shed surface every 15 meters to prevent the buffer film from sagging in the middle. The lower part of the buffer film is made of a steel wire of the same length as the length of the shed, which is placed in the "bag" of the buffer film, and is tightly fixed to the column on the rear side of the shed. After the buffer film is installed, the cold air entering the shed is first blocked by the buffer film to the rear wall to heat the cold air, thereby avoiding the dry edges of the leaves of the vegetables and the peeling of the fruits.

Buffer door construction buffer room

The entrance to the greenhouse is also a large vent. We will find that the vegetables near the entrance are always shorter. The main reason is that the door is leaking, the cold wind is entering the shed, and the temperature is low, which causes the plants to be low and the trees to be weak.

When the vegetable grower opens the door on the back wall or the east and west mountain walls, a buffer room can be set in the shed. A piece of film with a width of about 4 meters and a length of 6-10 meters is fixed on one side of the back wall of the shed, and is hoisted and fixed from the film and the shed by a steel wire or nylon rope. The membrane is sealed to form a closed space. When the vegetable farmer enters the shed, the film that picks up the head of the buffer room can be entered.

The entrance is at the front of the shed, and a rectangular space can be enclosed by a film on the inside of the door. The film can be hung from the wire of the scaffolding. When the vegetable growers enter the shed, they first enter the buffer room, and the cold air blown into the door is also blocked in the buffer room instead of directly blowing on the vegetables. The buffer room not only relieves the problem that cold air directly enters the shed, affects the growth of vegetables, but also places the clothes of the vegetable farmers to prevent the wet air in the shed from getting wet. At the entrance outside the shed, the vegetable grower can use the straw curtain to block the wind, but the straw must be tightly wrapped with a film to reduce the wind permeability of the straw curtain.

The venting of the second membrane should be carried out in several stages.

When the outside temperature is very low and the temperature inside the shed is difficult to meet the growth of vegetables, setting the second membrane is a good choice, which can raise the temperature in the shed from 3 °C to 5 °C. However, after the second membrane is installed, the humidity in the shed will increase significantly. How to reduce the humidity in the shed?

When releasing the wind, the air outlet of the second membrane should be opened first. After a period of time, the air outlet at the top of the greenhouse is opened for ventilation, and the moisture in the shed is excluded from the shed. It should be noted that if the temperature in the shed is still low, the air outlet of the second membrane and the air outlet at the top of the greenhouse should be staggered and ventilated to prevent the cold air outside the shed from blowing into the membrane, causing the temperature to continue to decrease and the vegetables to grow poorly. When closing the air vent, it should also be noted that when the temperature of the shed falls to 18 °C ~ 20 °C, the wind in the greenhouse will be closed first, the temperature of the shed will rise, and the moisture will rise with the hot air to the film between the membrane and the membrane. Then close the second membrane.

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