What are the precautions for watering greenhouse vegetables in winter
Reasonable watering is an important measure to ensure the healthy growth of greenhouse vegetables and increase yields. In view of the problems of low temperatures in winter and high humidity inside the greenhouse, the following precautions should be taken when watering greenhouse vegetables:
1. Pay attention to growth condition. Observe the growth condition of the plants. Usually when the plants are short of water, the leaves will wilt, growth will weaken, and blossom-end rot of the fruit will occur more often. At this time, water should be supplemented promptly.
2. Pay attention to soil moisture. Observe the soil moisture. If you water when the greenhouse soil is not dry, it will not only be unfavorable for raising the ground temperature, but also easily lead to poorer soil aeration, causing root hypoxia, resulting in root rot and the appearance of yellow leaves.
3. Pay attention to the weather. Before watering, be sure to watch the weather forecast. Not only should you choose a sunny day for watering, but you should also ensure that there are 2 to 3 sunny days after watering, so as to avoid encountering cloudy and rainy weather after watering, which would increase humidity inside the greenhouse, lower the ground temperature, and cause frequent diseases. This is even more important in deep winter. In the first two days after a sudden clearing following consecutive cloudy days, watering is also unsuitable. The greenhouse temperature and ground temperature should be raised first, so that the plants basically return to normal before watering.
4. Pay attention to ground temperature. The suitable daily average ground temperature for vegetable growth is about 22°C, while in deep winter, the ground temperature inside the greenhouse is mostly between 15°C and 20°C. If too much water is applied or the timing of watering is wrong, the ground temperature will drop rapidly, causing root damage and endangering the growth of the aboveground parts of the plants. Therefore, when the temperature is low, watering is best done after the straw mats are pulled open in the morning.
5. Pay attention to covering with plastic film. Covering with plastic film can not only reduce evaporation of water from the ground, maintain soil moisture, reduce the number of waterings, lower air humidity, and reduce the occurrence of diseases, but also raise the ground temperature and speed up the growth rate of vegetables.
6. Pay attention to moderate watering. For watering greenhouse vegetables in winter and spring, generally follow the principle of not watering unless there is a shortage and preferring dryness over wetness, keeping the water content of the soil around the vegetable roots at about 60%, preventing excessive and too frequent watering, and never using flood irrigation. Excessive watering can easily lower the air temperature and soil temperature inside the greenhouse, which is unfavorable for vegetable growth. Use small amounts of water frequently, or use a watering can to water each plant individually.
7. Pay attention to regulating water temperature. When the difference between water temperature and the temperature inside the greenhouse is more than 5°C, it can easily cause root damage. It is better to use deeper well water with a higher water temperature or pre-stored irrigation water inside the greenhouse.
8. Pay attention to management after watering. In the first two days after watering in winter, first raise the temperature to about 40°C at noon and keep the greenhouse closed for 1 hour to increase the ground temperature inside the greenhouse. Then increase ventilation to lower the humidity inside the greenhouse. Then, according to the diseases to which the planted vegetables are prone, spray pesticides for prevention to reduce the occurrence of pests and diseases.
Xinji City Agricultural Technology Center Zhang Yun