When will it last forever and when will it be short?

The winter solstice is longer and the summer solstice is shorter.

From the winter solstice, the direct sunlight position moves northward, and the daytime gradually extends, with an average daily increase of more than 90 seconds, that is, 1 min 30 seconds.

On the solstice of summer, the sun shines directly on the Tropic of Cancer. At this time, the daytime in all parts of the northern hemisphere reaches the longest in the whole year, and the higher the latitude, the longer the daytime. The solstice in summer is the turning point of the sun. After this day, I went back. The direct sunlight point moved southward from the Tropic of Cancer, and the daylight in the northern hemisphere became shorter and shorter day by day.

Agricultural activities in winter solstice and summer solstice

Winter is a good time to build water conservancy, carry out farmland capital construction and accumulate fertilizer. At the same time, wax fertilizer should be applied to prevent freezing.

Strengthen the management of winter crops, clear ditches and drain water, cultivate soil to back up roots, pay close attention to ploughing the uncultivated winter soil, loosen the soil, enhance the ability of storing water and preserving moisture, and eliminate overwintering pests. In the southern coastal areas where spring sowing has begun, it is necessary to do a good job in cold prevention of rice seedlings.

From summer to around, early rice heading and flowering in the south of Huaihe River, field water management should be fully water heading, wet irrigation, dry and wet, which not only meets the water demand of rice fruiting, but also can ventilate and nourish roots, ensure maturity and improve grain weight. As the saying goes, "Summer broadcasting does not allow noon", we should pay close attention to summer broadcasting, strengthen the management of broadcast content, and strive for full seedlings.

After the seedlings emerge, they should be spaced, fixed and transplanted in time to make up for the deficiency. During the summer solstice, all kinds of weeds in farmland grow as fast as crops. They not only compete with crops for water, fertilizer and sunlight, but also parasitize various germs and pests. Therefore, the agricultural proverb says, "If you don't hoe the roots and weeds in the summer solstice, it's like raising a poisonous snake to bite you." Grasping intertillage and hoeing is one of the important measures to increase production from summer solstice.

Generally, cotton has germinated, and its vegetative growth and reproductive growth are vigorous. Attention should be paid to ridging, intertillage and ridging in time, and ditch cleaning and drainage should be done in the field in rainstorm areas to prevent the harm of waterlogging and rainstorm.