Loose soil is beneficial to the root development and bulb expansion of onion. Generally, it is carried out 3-4 times in the seedling stage, and each watering is combined. The growth period of stems and leaves is 2-3 times, and planting is stopped after ridging. It is suggested that the planting depth is about 3 cm, the plant is shallow and far away from the plant. When the onion seedlings grow to three or four real leaves, they are transferred to the ground. Onions are usually planted before winter, and the weather is cold, so it is not suitable for flooding after planting. Proper control of irrigation to prevent excessive growth of seedlings. Proper irrigation control before harvest can improve bulb quality and storability. Onion leaves are cold-resistant, suitable for air with relative humidity of 60%-70%, and it is easy to get sick with high humidity. Dry soil promotes the formation of bulbs.
Field management In order to absorb nutrients when onions grow, they must be watered frequently to keep the fields moist. Urea should be applied with green water in spring, and potassium sulfate should be applied during bulb expansion.
Water and fertilizer are important factors affecting the growth rate of crops. Water management in onion field should keep the soil moist. After squatting, it is recommended to water the ball once every five days to promote the rapid expansion of the ball. During the vegetative growth period and tuber expansion period, fertilizers are absorbed quickly, among which potassium fertilizer, nitrogen fertilizer, calcium fertilizer and phosphorus fertilizer are used in large quantities. Avoid the stubble of vegetables such as onion, ginger and garlic. When planting, we should first classify, remove diseased seedlings, tillers and weak seedlings, and cut the seedlings into 2 cm long roots. Plant standard seedlings first, then sow and then plant.
Therefore, attention should be paid to the utilization of phosphorus, potassium and calcium in the later stage of topdressing, while maintaining the continuous supply of nutrients. Calcium, magnesium and boron should be supplemented in the later stage of topdressing to promote the stable increase of onion oil production. When the onion seedlings grow to three or four real leaves, they are transferred to the ground. Onions have a great demand for nutrition. Before transplanting, saprophytic organic fertilizer should be used as the main material, and then land consolidation should be carried out to make the soil sag Onions are usually planted before winter, and the weather is cold, so it is not suitable for flooding after planting.