1) For soil preparation and fertilization, it is better to choose sandy loam soil with fertile soil and rich organic matter for cultivation. It is necessary to prepare the land carefully, plow shallowly and harrow carefully to make the land level and make a border. The planting plots should be fully fertilized with basic fertilizers, usually organic fertilizers. 4,000-5,000 kilograms of organic fertilizer and 60-80 kilograms of ternary compound fertilizer should be applied per mu. Fertilizer should be applied shallowly and evenly. Generally, less fertilizer is applied in the south and more in the north. Irrigate the border with water before covering, and spray 150 ml of 33% field supplement herbicide per acre after the water seeps out.

(2) Sowing and seedling cultivation

1. Sowing period The sowing period of onions varies greatly in the north and south of China. In the southern subtropical areas, it is sown in late winter and harvested in late spring; in the Yangtze River and Yellow River basins, there are many It is sown in autumn, and the seedlings are planted before winter and harvested in summer; in Northeast China, they are sown in early autumn, planted in spring, and harvested in late summer or early autumn. Sowing in the Huang-Huai-Hai River Basin is usually done from September 10th to 20th

2. Improve the quality of sowing. The seedbed should be loose, fertile, and have strong water-holding capacity. Dry seed broadcasting is often used for seedling cultivation in autumn; seeds should be soaked and germinated before sowing in protected areas in spring. The seeding rate is generally 0.6-0.7 kg of seeds per 100 square meters of seedbed area, and the ratio of seedbed area to planting field is generally 1:15-20. If the density is too high, the seedlings will be thin and weak; if the density is too small, the seedlings will grow too thick and bolt easily.

3. Seedling management: Before the seedlings are unearthed, the soil should be kept moist to promote smooth emergence; after the seedlings are unearthed, the growth should be controlled through the amount of fertilizer and water to reach the appropriate seedling age standard for overwintering. When the seedlings grow too vigorously, fertilizer and water should be controlled; when the seedlings grow weakly, fertilizer and water should be supplied in time. Thinning and weeding are required when the seedlings are 5-6 cm tall.

(3) Planting

1. Timely planting. The planting of onions can be divided into planting before winter and planting in the following spring. In areas north of Beijing, planting is generally done in spring; in the Yellow River Basin, Yangtze River Basin and southern areas, planting is generally done before winter. The time is early November. Generally, planting is better when the seedling diameter is similar to the thickness of a chopstick (about 3-4 mm). If planted too early, the trees will grow large, which may easily lead to immature bolting; if planted too late, the root system will not fully develop, the cold tolerance will be low, and overwintering dead seedlings will easily occur.

2. Planting method: The planting border is generally made into a flat border, with a row spacing of 16-20 cm and a plant-to-plant spacing of 10-13 cm. About 30,000 plants per acre are planted. Varieties with a short growth period are suitable for dense planting; varieties with a long growth period are suitable for sparse planting; areas with good water and fertilizer conditions and fertile land are suitable for sparse planting, and vice versa. The suitable depth for planting is 2-3 cm, as long as the covering soil can bury the small bulbs. Sandy soil can be slightly deeper and clay soil should be slightly shallower. When planting, dig trenches according to row spacing, place seedlings according to plant spacing, and then cover with soil. It can also be planted according to the spacing between rows. When planting, bury the roots vertically to minimize damage to the roots, and water immediately after planting.

2. Management techniques

(1) Field management

1. Irrigation: Due to the low temperature, the seedlings planted before winter grow slowly and require little water. , water can be poured 1-2 times after planting to promote slow seedlings. After slowing down the seedlings, watering should be controlled, cultivating and soil loosening should be carried out to make the seedlings strong and strengthen their cold resistance. Pour winter water once before the soil freezes. It is required that the soil freezes at night and disappears by day after watering. The amount of water should be enough to allow all the water to penetrate into the soil. After returning to green in the next spring, pour green water in time to promote its green growth and keep the soil moist. It is not advisable to water frequently to avoid lowering the ground temperature. At the same time