In autumn, cold air activity becomes more frequent, and frost begins to appear in northern China. Frost can have serious negative effects on crop growth, so farmers must pay close attention and take timely protective measures to minimize the damage caused by frost.
Frost is generally categorized into two types based on the season: autumn frost and spring frost. Autumn frost, also known as early frost, refers to the first occurrence of frost in the fall. Conversely, spring frost, or late frost, refers to the last frost of the season. The period between the end of spring frost and the start of autumn frost is called the frost-free period. Depending on the cause, frost can be further classified into advection frost, radiation frost, advection-radiation frost, and evaporation frost.
Frost typically occurs under clear skies and low temperatures. The topography significantly influences the intensity and duration of frost. Different areas experience varying levels of frost. On slopes, for example, the southern side receives more sunlight and thus experiences less frost than the northern side. Similarly, the western slope tends to have less frost than the eastern slope. Soils that are moist and compact have a higher heat capacity and thermal conductivity, allowing them to absorb latent heat during condensation, which helps reduce frost formation. Frost is rare under forests or tree canopies. When the diameter of a forest hollow is 3 to 20 times the height of the trees, frost is more severe. However, if the diameter is less than three times or more than 20 times the tree height, frost intensity decreases. On the windward side of a forest, cold air movement can lead to advection frost.
Frost damage to crops is mainly seen in two ways: first, it causes mechanical damage to plants, and second, it severely affects wheat. After wheat enters the jointing stage in spring, its cold resistance decreases, making it more vulnerable to sudden temperature drops. Spring frosts can cause serious damage within just a few hours, often worse than winter frosts.
To prevent frost, farmers use various methods such as fumigation, irrigation, spraying, planting protective forests, and using covers. Additionally, agricultural practices like selecting cold-resistant and early-maturing varieties, sowing at the right time, cultivating strong seedlings, and improving soil quality are also effective in reducing frost damage. Li Chunsheng
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