First, the nutritional characteristics of Chinese cabbage. Each 1000 kg of Chinese cabbage is about 1.5 kg of nitrogen (N), 0.7 kg of phosphorus (P2O5) and 2.0 kg of potassium (K2O). The absorption ratio of nitrogen, phosphorus and potassium is about 1:0.46:1.33 throughout the growth period. The most absorbed potassium is followed by nitrogen and at least phosphorus. Chinese cabbage is sensitive to sulfur. For chlorine-free crops or crops with poor chlorine tolerance, it is certainly good to apply sulfur-based fertilizers. However, production practice in recent years has proved that as long as the soil is not saline-alkaline soil, the water seepage is good, and the application of chlorine-based fertilizer will not affect the yield. Calcium deficiency in Chinese cabbage is easy to get heartburn. Hebei Province is a calcareous soil area. The soil is rich in calcium, mainly due to the absorption of calcium ions by the application of a single ammonium nitrogen fertilizer.

Second, the vegetative growth stage of Chinese cabbage. After sowing and emergence, they successively enter the seedling stage, the rosette stage (ie, the group period), the core period, and the ball stage. The number of early maturing varieties in the seedling stage is 12-15 days; the late maturing varieties are 17 to 18 days, and 5 to 10 leaves have been grown; the cumulative number of days in the rosette period is 20 to 21 days, and the late maturing varieties are 27 to 28 days; The cumulative number of days is 25 to 30 days for early maturing varieties and 40 to 45 days for late-maturing varieties. The cumulative number of days in the ball-forming period accounts for half of the total growth period, and the growth amount accounts for 2/3 to 3/4 of the total weight. Meeting the nutrient requirements of the above main growth stages is the key to high quality and high yield.

Third, the main points of fertilization of Chinese cabbage.

1. Base fertilizer: First of all, it is necessary to apply enough base fertilizer, 3,000 to 5,000 kilograms of organic fertilizer applied to the soil, and 30-40 kilograms of suitable formula fertilizer, and apply it before turning over the ground to achieve the compatibility of soil and fertilizer. For the sulfur type of 12-20, 18-12-18, 16-16-16, etc., the chlorine type such as 19-19-19, 18-18-18, 17-17-17 can also be used.

2, top dressing: Chinese cabbage topdressing mainly captures the seedling stage, the rosette stage and the ball stage. Fertilizers such as 18-12-20, 18-12-18, and 34-0-16 should be used as top dressing according to the type of bottom fertilizer applied, and the topdressing stage of the applied base fertilizer can be used without top dressing. It is better if the balling period can be matched with the application of nitrate nitrogen fertilizer. The amount of topdressing per mu is 15-20 kg. It can be applied in the inter-row ditch, the inter-plant hole and timely covering the soil, preferably in combination with watering, inconvenient operation during the rosette period and the ball-forming period can be combined with watering.