Cotton topdressing must be appropriate in advance

From the beginning of cotton flowering period to the period of vigorous fertility, it needs more fertilizer, more nitrogen and more intensity. From then on, the nitrogen uptake accounts for 60% of the nitrogen uptake during the whole growth period. The phosphorus and potassium needed during this period are also It accounts for more than half of the total.

The principle of fertilization of high-yield cotton is to timely grasp the topdressing management on the basis of the base fertilizer. In recent years, the development trend of high-yield cultivation management of cotton is to achieve high yield by increasing the density of sandalwood under the conditions of systematic control. This high-yield method is particularly prominent in the Xinjiang cotton area. In addition, in the Yangtze River Basin and the cotton planting area in North China, in order to ensure the continuous improvement of cotton and food crops, in recent years, there has been a trend of shortening the growth period of cotton and vigorously developing summer cotton. For these two new developments, there must be corresponding new countermeasures in the management of cotton topdressing.

In the past, the spring planting of cotton was the main focus, emphasizing the rearward shift of topdressing (mainly referred to as nitrogen fertilizer), and the goal was to strive for “three peaches”, that is, high-yield plants characterized by cotton plants with peaches, succulents, and autumn peach tops. On the topdressing, the principle of reapplying the weight of the fertilization center of the fertilization and applying the topping fertilizer was proposed. However, the current situation is different, and it is necessary to move forward in the period of topdressing. Under the conditions of chemical control of the ketamine system, early application of bud flower fertilizer has a good effect on the high yield of spring cotton, such as early enhancement of root activity. Therefore, the application of chemical control technology provides a guarantee for adjusting the time of topdressing. In the cotton field before the ridge is closed, it can reduce the mechanical damage of labor and cotton plants. Especially the summer cotton or short-season cotton must emphasize the early topdressing in the bud period. Cotton seedlings are early, avoiding the threat of late maturity. In short, under the premise of adopting systematic control, the whole process of cotton fertilization is based on base fertilizer, and the principle of proper application of topdressing is applied. In recent years, cotton high-yield slab fields have shown that proper early topdressing is beneficial to root growth and premature root failure prevention under conditions controlled by ketamine. It is feasible to apply the top dressing in combination with the buds in the bud stage (4~5 leaves) in advance. It is also feasible to carry out top dressing at the initial flowering stage (one or two young bells have been hung).

The topdressing in the bud stage or the early flowering stage is mainly to add appropriate nitrogen fertilizer (such as 10~15 kg/mu urea), in the potassium-deficient soil, the low effective potassium content (such as the sandy loess with strong sandy soil) or the base fertilizer. In the cotton field of potash and organic fertilizer, 5-6 kg of potassium chloride should be added. At this time, chasing potassium can promote the growth of cotton boll. Especially for some plots of insect-resistant cotton varieties, the amount of potash should be higher than that of ordinary cotton varieties to meet the high yield.

The application method of top dressing should be mixed with fertilizer and timely watering. Urea should not be applied to avoid loss of volatilization or fumigation of cotton leaves. In production, urea is often sprinkled on the surface and rain, neither covering soil nor timely irrigation. This method of fertilization is not scientific.

In addition, for high-yield and super-high-yield cotton fields, if there is a weakening of the growth momentum or automatic capping in the late stage of cotton bolls, 5-8 kg of urea should be added in time to prevent the early decline of cotton plants for the autumn peach.