What impact does early frost and late frost have on agriculture?

Frost solar term is the eighteenth among the twenty-four solar terms, and it is also the last solar term in autumn. It ranks among the autumn solar terms, after the Beginning of Autumn, the end of summer, the white dew, the autumnal equinox, and the cold dew, so it ranks The sixth solar term of autumn.

Frost occurs every year from October 22nd to 24th. It is when the sun reaches 210° of ecliptic longitude and the Big Dipper is at Xu. At this time, the direct point of the sun is far away from the northern hemisphere and in the southern hemisphere, so The northern hemisphere is far away from the direct sunlight, and the heat weakens, and the northern hemisphere enters autumn and winter. This year’s frost festival falls on October 23rd.

The ancient book "The Collection of the Seventy-two Hous of Yue Ling" records the frost: "In the middle of September, the air is solemn and condensed, and the dew condenses into frost." From this sentence, we can see that, After the frost solar term, the temperature is relatively cold in the morning and evening. When the weather is clear and the humidity is high at night, when the ground temperature reaches 0℃, dew can condense into frost. After the frost season, the cold air in the north becomes stronger and cold waves become more and more common.

There is a saying in rural areas: "When there is frost in September, there is no frost, but when there is frost in October, there is frost." It seems that frost is in September and October. Let’s analyze the meaning of this sentence specifically.

September frost and no frost: It means that if the frost solar term arrives in September of the lunar calendar, the weather will be warmer, so when the frost solar term arrives, the humidity may be there, but the surface temperature will not yet reach 0℃, so there is no frost.

Frost in October: It refers to the frost festival in October of the lunar calendar. Winter has entered October of the lunar calendar. At this time, the weather is cold. The surface temperature is low in solar radiation at night and the temperature is 0℃. Or below, so when the dew is sufficient, white frost will appear in the open countryside. As the weather gets colder and sunny, there will be frost, very thick frost.

This year is the frost in September, which means there may not be any frost when the frost comes. However, it is normal weather conditions for frost to fall during the frost season. Because this year is a leap month, there is an extra April, so the subsequent dates are postponed by a month. Frost will fall in September, will the weather be warm in winter? This is not necessarily true, because this year there was widespread snowfall and cold weather in the north in early October. Authoritative meteorological experts said that this was caused by the La Ni?a phenomenon, and La Ni?a phenomenon can bring disasters such as cooling, explosive snow, ice and snow. We will have to wait and see how severe the La Ni?a phenomenon will be this winter.

No matter what, farmers still need to be well prepared and plant various winter crops before frost, such as winter rapeseed and winter wheat. After frost, it is a bit late, which is not good for later germination. Crops management in winter must also be diligent, field drainage ditches must be well prepared, and farmyard manure must be prepared in winter.