There are principles for watering winter shed vegetables
The time for watering sunny and not overcast should be selected according to different weather conditions. Strictly follow the principle of watering on sunny days, watering less or not on cloudy days, and avoid watering on rainy and snowy days, especially in cold currents and snowy weather to avoid watering. The drop in ground temperature will cause the roots of vegetables to die, or increase the air humidity in the shed, leading to the occurrence and spread of diseases.
Small watering, not large watering, the temperature is low in winter, and the water demand of vegetables is small, so the watering frequency should be small, the watering volume should be small, and flood irrigation is not allowed. Under normal circumstances, small watering is done alternately, and the watering amount is only half of summer. For example, overwintering cucumbers can be watered alternately, twice in small rows and once in large rows, and irrigated alternately.
Water temperature is not cold Watering water should be preheated in the shed first, and then watered when the water temperature is close to the ground temperature, the water temperature is not less than 12 ℃. Can not directly use river water, reservoir water and cold water in ponds for irrigation. After watering, turn off or even close the vents to make the temperature in the shed reach above 30°C and continue for 1 to 3 hours.
Watering the vegetables in the greenhouse in the dark and not irrigating in the winter should insist on under-film under-film irrigation, or under-film micro-irrigation, which can prevent the evaporation of ground water, reduce the air humidity in the shed, and prevent the occurrence of diseases. The use of micro-irrigation has a positive effect on the balance and coordination of water, fertilizer, gas, and heat required for vegetable growth, especially in the early and mid-term use of micro-irrigation, which is conducive to promoting roots and seedlings, controlling the air humidity in the shed, and reducing the occurrence of diseases and insect pests. It can also effectively control water volume, reduce deep leakage water volume and fertilizer loss, improve soil structure and performance, promote crop growth and improve vegetable quality.
Precautions
Decide whether to water the plants according to the growth condition. When the plants are lack of water, the leaves will wilt, the growth will be weakened, and fruit umbilical rot will occur more frequently. At this time, water should be added in time. If watering in the greenhouse soil is not dry, not only is it not conducive to increasing the ground temperature, but also easily leads to poor soil air permeability, resulting in hypoxia in the root system, resulting in retting and yellow leaves.
Check the weather before watering not only to choose sunny watering, but also to ensure that there are 2 to 3 days of sunny weather after watering to avoid rainy weather after watering, resulting in increased humidity in the shed, lower ground temperature, and frequent diseases. In the deep winter season, you need to pay more attention. It is not suitable for watering in the first two days when it is sunny after a continuous cloudy day. You should raise the gentle ground temperature of the shed to make the plants basically return to normal before watering.
Watering time is reasonable. Winter greenhouse vegetables should be watered around noon, preferably after 10 am and before 3 pm. The temperature of the greenhouse is higher during this period, and the side effects after watering are minimal. Avoid watering in the morning and evening to prevent freezing damage to vegetables. Watering should use well water as much as possible, because the temperature of the well water is higher, which can reduce the physiological stimulation to the vegetables. The method of water storage and temperature increase can also be adopted, that is, a reservoir is built in the greenhouse, and the temperature of the water is raised through the reservoir before watering the vegetables. This method is simple, practical, and effective. The disadvantage is that it takes up some space in the shed.
Watering in different parts has a large temperature difference in each part of the shed, and the amount of watering must also be different. For example, the southern part of the shed and near the stove, flue and other heat sources have higher temperatures, and the evaporation of soil moisture is large. It is better to be larger; the temperature on the east, west and north of the greenhouse is lower, the sunshine time is short, and the amount of watering should be less.
Strengthen management after watering. After watering in winter, it is easy to cause problems such as low temperature, high humidity, and many diseases in the greenhouse. Therefore, the first two days after watering, the temperature should be raised to 30°C or more at noon, and the shed should be stuffy for 1 hour to increase the ground temperature in the greenhouse. Then increase the ventilation and reduce the humidity in the shed. For the vegetables planted to be vulnerable to disease, spraying prevention measures to reduce the occurrence of vegetable diseases and insect pests in greenhouses.
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