Is there any way to prevent frost?

Frost means that the temperature of the ground and plant surface drops to a low enough temperature during the crop growing season, resulting in crop injury or death. When there is frost, there can be frost (white frost) or no frost (black frost). When there is frost, crops may not suffer frost. Therefore, we should prevent frost rather than frost.

Frost occurs in weather conditions that may lead to significant cooling. The meteorological conditions for frost formation are clear and breezy nights. Clear at night is beneficial to the rapid radiation cooling of the ground or ground objects. On the eve of first frost, it was sunny and cloudless at night. Ground radiation transfers heat to the upper atmosphere, and the inverse radiation of the atmosphere is weak, and the heat returning to the ground is less, and the ground temperature drops greatly. Therefore, on the eve of first frost, the temperature was low, people felt very cold, and the weather was generally sunny the next day. Therefore, there is a saying that it is sunny in first frost. In the Book of Qi Yaomin, there is also a saying that "it rains and sunny, and the north wind is cold, so there is frost at night." A scientific exposition of ...

The reason why frost harms crops is that low temperature promotes the water between plant cells to form ice crystals, and continues to capture the water in the cells. The ice crystals gradually expand, which not only consumes the water in the cells, but also causes the protoplasm to dehydrate and deteriorate the protoplasm colloid. Thereby dehydrate cells and cause injury; The metabolic process is destroyed, the protoplasm structure is destroyed, and the ice in the cell is mechanically damaged.

The intensity and duration of frost occurrence are closely related to topography, soil, vegetation, agricultural technical measures and crops themselves. The north slope of the mountain faces the cold wind, with less sunshine and heavy frost; On the south slope, the lee is sunny and the frost is light. On the east and southeast slopes, the sun shines first in the morning, and the plant temperature changes greatly, and the freezing damage is often heavier. The cold air on the hillside can go down the slope, and the frost is lighter, while the cold air accumulates in the valleys and depressions below the mountain, and the frost is heavier; Loose soil, small heat capacity and low thermal conductivity make the temperature of the air layer near the ground drop rapidly, and crops are seriously damaged by frost, while the soil is tight and wet.

Preventive measures for spring frost;

(1) Fumigation method: On the night of frost, smoking in the field can effectively reduce and avoid frost disasters. However, we should pay attention to two points: first, the fireworks should be properly dense, so that the smoke screen can basically cover the whole park; Second, the ignition time should be appropriate. Ignition should be carried out against the wind from midnight to 2-3 am, and smoke will still cover the ground until sunrise, which will have the best effect.

(2) Water spraying method: Before frost occurs, spraying water on the surface of plants with a sprayer can slow down the temperature drop of plants, increase the water vapor content in the atmosphere, and release heat from water vapor condensation, thus alleviating freezing injury. In the days of obvious frost, you can spray water many times.

(3) Wetland method: wet soil has large heat capacity, high thermal conductivity and slow surface cooling. Therefore, watering the tea garden ground can reduce the frost intensity before the frost occurs. This method is generally used at the same time as water spraying.

(4) Covering method: covering the tea crown with straw curtains and films. This method is suitable for small areas. Because of the high cost, white tea and the first batch of high-grade tea to be picked must be used.

(5) Frost washing method: In case of frost, water or spray water to wash the frost before the sun comes out, which can reduce the frost damage of crops.