Foliar topdressing of cotton is necessary in the later stage.

This weather phenomenon of drought before and rain after transplanting is very disadvantageous to the survival and growth of cotton after transplanting, and the growth process is about 10 days later than usual. In order to improve the rate of flower bud formation and boll formation in the later stage of cotton, it is suggested that the majority of cotton farmers should strengthen fertilization management by foliar spraying, the specific methods are as follows: 1, combined with pest control to grasp the rhythm of fertilizer. Foliar fertilization combined with pest control should not be applied every time, but should be cross-applied according to different types of nutrients such as nitrogen, phosphorus, potassium and trace elements. The same nutrient should be sprayed once every 7-10 days, and the interval of different nutrients can also be 3-5 days. That is, if nitrogen fertilizer is used for the first time, phosphorus and potassium fertilizer will be used for the second time, and trace element foliar fertilizer can be used for the third time. 2. Select the varieties to ensure the coordination of nutrients. Urea is an ideal variety of nitrogen fertilizer for foliar spraying, which is dripped with about 0.5% aqueous solution at the later stage of cotton growth. Potassium dihydrogen phosphate is suitable for phosphorus and potassium fertilizer with a concentration of 0.2%. Trace element foliar fertilizer can effectively reduce the symptoms of element deficiency in the upper leaves and improve the boll setting rate. In recent years, Xingxin Fulisu developed and popularized by provincial soil and fertilizer station is a new generation of humic acid liquid fertilizer, which has the characteristics of high concentration, high content, high activity and high effect. The use of this product can make the root system developed, the plant strong, enhance photosynthesis, regulate plant physiological function, promote plant growth and dry matter accumulation, so as to increase yield and improve quality. 3. Flexible regulation to improve photosynthetic efficiency. Foliar fertilization should also be flexibly regulated according to the different growth of cotton: the weak cotton is generally dominated by nitrogen, combined with the application of phosphorus and potassium fertilizer; the general growth is mainly based on the combination of nitrogen, phosphorus and potassium; those with strong growth are mainly phosphorus and potassium, combined with Zhuangzhang chemical control, using 3-3.5 grams of pure Zhuangzhuangsu plus water per mu. Trace element foliar fertilizer can be applied to all kinds of cotton, especially in the first and second class fields.