On May 5th or 6th every year, "Dou refers to the southeast, and the dimension is long summer. Everything grows here, and the sun reaches 45 degrees of the Yellow Meridian, hence the name Long Summer Leaf, that is, 20 1 1 the fourth day of the fifth lunar month, 201/Long Summer Friday. The long summer solar term was established at the end of the Warring States Period (239 BC). The long summer indicates the change of seasons, and it is a summer day with four seasons according to the lunar calendar in ancient times. For example, The Interpretation of Yizhoushu Poems says: "On a long summer day, the sound is like cricket. On the fifth day, the earthworm came out. Five days later, Wang Guasheng was born. "It describes the phenological scene at the beginning of Xia Meng." Twenty-four solar terms "says:" It is the beginning of long summer again, when Xia Zhishi was established and everything was false. The "false" here, that is, "big", means that the plants sown in spring have grown upright. In fact, according to the standard of climatology, the daily average temperature rises to above 22℃ steadily, starting from summer. In astronomy, Chang Xia said that this is the beginning of summer bidding farewell to spring. When the temperature rises obviously, the summer heat comes, thunderstorms increase and crops enter the peak season, people are used to taking long summer as an important solar term. Before and after the "Long Summer", only the area south of Fuzhou-Nanling Line in China is really the summer of "the trees are dark and the moon is clear, and the balcony reflection is like a pond", while some areas in the northeast and northwest have just entered spring at this time, and the average temperature in most parts of the country is around 18 ~ 20℃, which is the mid-spring and late spring season of "letting a hundred flowers blossom". In May, Sophora japonica blooms in many places.

In ancient China, the long summer was divided into three periods: "First, waiting for the cricket's cry;" Second, wait for the earthworm to appear; Wait for Wang Guasheng. " That is to say, in this solar term, you can first hear kangaroos (that is, crickets) croaking in the field (that is, frogs), then you can see earthworms digging in the soil, and then the vines of the king melon begin to climb and grow rapidly.

In the long summer, everything is thriving. The book "Eight Chapters of Lotus Life" written by the Ming Dynasty said: "On the day of summer dream, heaven and earth began to merge and everything was beautiful." At this time, the summer harvest crops entered the late growth stage, the winter wheat blossomed and filled, the rape was close to maturity, and the summer harvest crops were basically a foregone conclusion that year. Therefore, there is a saying in agricultural proverbs that "see summer in the long summer". Rice planting and management of other spring-sown crops have also entered a busy season. Therefore, China has always attached great importance to the long summer solar terms. According to records, during the Zhou Dynasty, on the day of long summer, the emperor personally led hundreds of civil and military officials to the suburbs to "welcome summer" and instructed Si Tuleideng and other officials to encourage farmers to work hard. After the long summer, Jiangnan officially entered the rainy season, and the rainfall and rainy days increased significantly. Continuous rainy days not only caused wet damage to crops. It will also cause the prevalence of many diseases. The heading and flowering period of wheat is the most susceptible period to scab. If warm but rainy weather is expected in the future, close attention should be paid to spraying chemicals from the early flowering period to the full flowering period. Cotton in southern China often causes outbreaks of anthracnose, damping-off and other diseases under the weather conditions of continuous rain or sudden warming and cold, resulting in large-scale dead seedlings and lack of seedlings. Necessary measures to increase temperature and reduce humidity should be taken in time, combined with chemical control to protect seedlings and strive for strong seedlings. "There are many kinds of seedlings in the long summer, and more millet is harvested in Man Cang", and it is the red season of early rice transplanting in the north and south of the Yangtze River before and after the long summer. Full-moon seedlings can be planted, but full-moon grass can't be planted. At this time, the temperature is still low. Immediately after planting seedlings, we should strengthen management, topdressing early, ploughing early, controlling pests early and promoting development early. Pay close attention to tail sweeping when sowing mid-season rice. At this time, the spring shoots of tea trees develop fastest. If we ignore them, tea leaves will get old. As the saying goes, "Grain Rain picks less and doesn't pick it in the long summer", so we should concentrate our efforts and harvest it by surprise in batches.

Before and after the long summer, the temperature in North China and Northwest China rose rapidly, but the precipitation was still not much. In addition, the wind is strong and evaporation is strong in spring. Atmospheric dryness and soil drought often seriously affect the normal growth of crops. Especially, the dry hot wind before and after wheat filling and milk ripening is an important disastrous weather that leads to yield reduction, and timely irrigation is the key measure for drought resistance and disaster prevention. "hoes are everywhere for three days in the long summer", when weeds grow rapidly. "Don't mow the grass for one day, and don't mow it for three days." Intertillage weeding can not only weed, resist drought and prevent waterlogging, but also increase the ground temperature and accelerate the decomposition of soil nutrients, which is of great significance to promote the robust growth of crops such as cotton, corn, sorghum and peanuts at seedling stage.