Topdressing management techniques of onion

After the onion was planted, the root system grew first, then turned to the aboveground growth, and the local upper part grew fully before entering the bulb hypertrophy growth period. According to the growth and development characteristics of onion, topdressing by stages is one of the keys to the high yield of onion. Slow seedling fertilizer: slow seedling fertilizer 15 to 20 days after planting to replenish nutrients for the continued growth of the root system while preparing for the growth of the aboveground parts that will begin soon. Urea 5kg / mu was sprinkled and watered to facilitate absorption and utilization. Hair fertilizer: 30 days after planting, when the vegetative growth is strengthened, fertilizer should be applied to ensure the growth of aboveground functional leaves. Because the size of the leaf vegetative body is closely related to the size of the bulb, and the promotion of leaf growth in the early stage lays the foundation for the hypertrophic growth of the bulb in the later stage. Mainly nitrogen fertilizer, 5kg urea and 5kg potassium sulfate per mu. Head-stimulating fertilizer: after the plant has 8 or 10 tubular leaves, the bulb begins to expand, and the head-promoting fertilizer should focus on the middle stage of bulb expansion growth. Nitrogen fertilizer should not be applied too much when the bulb begins to grow. In the later stage of bulb expansion, excessive application of nitrogen fertilizer will occur "greed" and affect harvest. Urea 5kg / mu and potassium sulfate 8kg / mu. In the bulb expansion period, potassium deficiency will not only reduce the yield, but also have a certain effect on the storability of the product.