Cultivation techniques of Chinese Cabbage in Spring

The main results are as follows: (1) Variety selection: at present, the main varieties suitable for the cultivation of Chinese cabbage in spring are spring general and spring crown. (2) sowing and raising seedlings: Chinese cabbage seedlings can pass vernalization after 15-20 days at 5 ℃, resulting in immature bolting. The suitable time for seedling sowing in open field should be in the middle and last ten days of March, and be on the market in the first and middle of May. To raise seedlings in greenhouse and small arch shed, it is appropriate to sow seeds in mid-late February and appear on the market in late April. Because adding a small arch shed in the greenhouse can increase the temperature of Chinese cabbage at the seedling stage, make the temperature higher than 5 ℃ without vernalization, and solve the problem of early bolting. (3) soil preparation and fertilization: there are more Rain Water in spring, and topdressing is often inconvenient, so it is necessary to re-apply base fertilizer before soil preparation. ① base fertilizer: generally 667 square meters can be used better mature farm fertilizer 5-7.5 tons, plant ash 100kg, calcium superphosphate 25kg or high-quality ternary compound fertilizer 100kg, potash 30kg. Combined with the ploughing and harrowing process, it can be evenly mixed with the soil. ② as a border: it is better to use "high ridge and narrow box" as the form of border. Its advantage is that it can deepen the plough layer, promote the development of root system, facilitate ventilation, reduce the occurrence and harm of diseases and insect pests, and is conducive to drainage. Generally, the height of the border is 25 cm, the width of the border is 80-120 cm (excluding soil ditch), and 3-4 plants are planted. (4) reasonable close planting: Chinese cabbage is cultivated in spring, because of the short time, it is suitable for close planting, the general row spacing is 35 × 30 cm. (5) Field management ① ploughing and weeding: generally, watering water to fix roots and raising seedlings after planting, ploughing timely after watering or rain, preventing ground hardening, promoting soil permeability, and removing weeds. At this time, the ploughing should be shallow, to hoe the topsoil as the degree, do not hurt the roots. ② water and fertilizer management: in spring, water management is mainly to pay attention to drainage and waterlogging prevention. Fertilizer management is mainly based on the premise of adequate application of base fertilizer, topdressing according to seedling conditions in each growing period. Rosette stage: generally apply 2.5 tons of human feces and urine and 10 kg of urea. Heading period: focus on the initial and middle stages of heading. In both cases, quick-acting fertilizers should be used and applied in advance. Generally at the beginning of the heart immediately topdressing, every 667 square meters with human and animal feces and urine 1 ton, urea 10-15 kg. Topdressing again after the drum, and combined with the application of 20 kg potash fertilizer. ③ pest control: the main diseases of spring Chinese cabbage are soft rot and downy mildew. The main pests are cabbage insects and aphids, which can be controlled with reference to the relevant techniques of pest control.