In the winter, in the vegetable cultivation management of greenhouses, high humidity tends to make plants grow, or induce roots, causing plant death, and creating conditions for the occurrence and spread of various diseases of vegetables. How to control the humidity in greenhouses in winter, Professor Zhang Heyi of the Academy of Agricultural Sciences of Northwest A&F University reminded farmers to start from the following points.
Covering the non-drip film without dripping film can overcome the drawbacks of attaching a large amount of water droplets on the inner side of the film, obviously reducing the humidity, and having good light transmission performance, and the light transmittance is 10%-15% higher than that of the general agricultural film, which is favorable for temperature increase and humidity.
Reasonable ventilation and air release are the main measures for dehumidification. Generally, the temperature is high when the temperature is high around noon. The top wind and the waist wind are the mainstays. The bottom wind can not be placed to prevent the greenhouse temperature from being too low and the sweeping wind to hurt the seedlings. In the harsh winter and early spring, it is not advisable to put early wind and dehumidification, but the cooling caused by ventilation should be based on the premise that the crop does not suffer from chilling damage.
Covering the mulch film in the shed is made by the size of the ridge and the distance between the mulch and the mulch cover. When watering, the water flows in the small ditch under the mulch. The mulch prevents the evaporation of moisture, which prevents the humidity of the indoor air in the shed from being greatly increased after watering.
Reasonable watering and watering are the main factors leading to the increase of humidity in the greenhouse. Generally, it should be poured with small water or grooved water, and should not be watered or flooded. When the temperature in the shed is low, especially when the air is not ventilated, the watering should be controlled as much as possible. Watering should be carried out on sunny days 10-12 am, with ventilation and drainage, not watering in the afternoon, cloudy days and rain and snow.
The relative humidity in the air drops by 3%-5% for every 1 °C increase in the indoor temperature of the heating and cooling shed. When the plant grows to have strong resistance, the watering can be heated up to about 30 °C for 1 hour, and then ventilated and drained. It can be repeated once after 3-4 hours when the shed temperature is lower than 25 °C.
The humidity of the air in the dust dehumidification shed is inherently large, and the use of the conventional spray method also increases the humidity, which is detrimental to the prevention and treatment of diseases. By using the dust method and the smoke method, it is possible to avoid increasing the humidity of the air due to the spray and improving the control effect.
When the temperature of the greenhouse is high, the surface of the greenhouse is shallow, and the surface water is evaporated, and the pores of the soil are cut off to prevent the deep water from moving up.
Natural moisture absorption in the shed can use straw, wheat straw, quicklime and other materials to spread water vapor or fog between the rows to achieve the purpose of reducing humidity.
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