The air outlet can't be opened. Why can't the greenhouse grow vegetables?
Many vegetable farmers report that one vegetable in the greenhouse is not growing well, while the vegetables at the other end of the greenhouse are growing well, especially some colorful eggplant vegetables, such as tomatoes, which always bear green fruits at one end of the greenhouse. Because the wind direction is not considered when the wind is released, the size of the air outlet in the greenhouse is the same, resulting in different temperatures at both ends of the greenhouse.
When the west wind blows, the wind will enter the shed along the air outlet, causing the temperature at the east end of the shed to drop. Vegetable farmers can properly lower the air outlet at the east end while increasing the air outlet at the west end of the shed, so as to reduce the temperature at the west end of the shed and ensure the same temperature in the shed. On the contrary, the same management measures should be taken in case of easterly winds or easterly winds. When the wind blows south or north, the air outlets on the east and west sides of the greenhouse can be opened to the same size.
Only by properly adjusting the size of the air outlets at both ends of the greenhouse according to the different wind directions to ensure the same temperature in the greenhouse can the synchronous growth of vegetables be promoted. In addition, in the greenhouse, because the two gables of the greenhouse absorb heat when exposed to light, the temperature at both ends of the greenhouse rises slowly, which makes the temperature at both ends of the greenhouse lower than that in the middle of the greenhouse. In the case of fresh air, vegetable farmers should open the air outlets at both ends of the greenhouse slightly smaller.
Because of the low temperature in autumn and winter, after covering the grass curtain at night, the vegetables in the greenhouse stop photosynthesis and only breathe and release a lot of carbon dioxide. At the same time, microorganisms in the soil decompose organic matter and also release carbon dioxide. After one night, the carbon dioxide content accumulated in the greenhouse increased obviously, which was much higher than that in the external atmosphere. The next morning, when the grass curtain was opened, the sun began to shine, and green plants such as vegetables began to photosynthesis, which required a lot of carbon dioxide. At this time, the concentration is high, just enough raw materials can be given to vegetables, which are converted into nutrients through photosynthesis and stored in vegetables. In the hour before the outdoor air comes out, the organic matter accumulated by plants through photosynthesis will be several times as much as usual, which is conducive to the increase of vegetable yield.
The thermometer is an important basis for vegetable farmers' fresh air, and its accuracy is directly related to whether vegetables are in an environment suitable for growth. Some vegetable farmers only set a thermometer at one end near the shed door to read the temperature conveniently, which is not desirable because the temperature near the shed door is relatively low. If the vent is adjusted according to the displayed temperature, it will inevitably lead to the high temperature in the shed and affect the normal growth of vegetables. It is suggested that vegetable farmers should set three thermometers evenly in the east-west direction in the shed, and then take the average value to reduce the error, and the lower end of the thermometer should be placed about 10 cm above the vegetable growth point.
Because the wind direction is not considered when the wind is released, the size of the air outlet in the greenhouse is the same, resulting in different temperatures at both ends of the greenhouse. When the wind direction is different, the temperature in different parts of the shed is different: when there is no wind or a slight northeast wind (or southeast wind), the temperature at the west end of the shed is generally 2-3 degrees higher than that at the east half, and when the wind is strong, the temperature at the east end is about 2 degrees higher than that at 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 greater the wind, the greater the temperature difference.