How to fertilize Chinese cabbage scientifically? Please keep this guidance

????1. Fertilization principles

In view of the serious problem of blindly applying excessive nitrogen fertilizer in Chinese cabbage production, excessive single application rates, unreasonable nitrogen-phosphorus-potassium ratios, blind application of high-phosphorus compound fertilizers, insufficient application of organic fertilizer in some areas, and severe acidification of vegetable garden soil, the following fertilization principles are proposed:

(1) Optimize the amounts of nitrogen, phosphorus and potassium fertilizers according to soil fertility conditions and target yield;

(2) Base fertilizer is the main approach, combining base fertilizer with topdressing. Topdressing should be mainly nitrogen and potassium fertilizers, with appropriate supplementation of trace elements. Strengthen topdressing management after the rosette stage; an additional topdressing is needed in the early heading stage; nitrogen topdressing should not be applied 2 weeks before harvest;

(3) Available boron in calcareous soils in the north and available molybdenum in strongly acidic soils in the south are relatively low in content, so attention should be paid to supplementing trace elements;

(4) When vegetable garden soil is severely acidified, acidic soil amendments such as lime should be applied in appropriate amounts;

(5) Avoid using organic fertilizers that are not fully decomposed; advocate the use of commercial organic fertilizers and decomposed farmyard manure to build up soil fertility.

????2. Fertilization recommendations

(1) For a yield level of 4500-6000 kg/mu, apply 4 cubic m/mu of organic fertilizer; nitrogen fertilizer (N) 10-13 kg/mu, phosphorus fertilizer (P2O5) 4-6 kg/mu, potassium fertilizer (K2O) 13-17 kg/mu;

(2) For a yield level of 3500-4500 kg/mu, apply 3-4 cubic m/mu of organic fertilizer; nitrogen fertilizer (N) 8-10 kg/mu, phosphorus fertilizer (P2O5) 3-4 kg/mu, potassium fertilizer (K2O) 10-13 kg/mu. For plots prone to boron deficiency or where boron deficiency symptoms have already appeared in previous years, 1 kg of borax per mu can be applied as a base application before sowing, or in the mid-to-late growth stage a 0.1%-0.5% borax or boric acid aqueous solution can be sprayed on the leaves, once every 5-6 days, for 2-3 consecutive sprays; Chinese cabbage is a calcium-loving crop, so in addition to base application of calcium-containing fertilizer (superphosphate), leaf supplementation can also be adopted by spraying 0.3%-0.5% calcium chloride or calcium nitrate. When the soil pH of vegetable gardens in the south is less than 5, 100-150 kg of quicklime per mu needs to be applied, which can reduce soil acidity and supplement calcium. All organic fertilizer and phosphorus fertilizer should be applied as basal fertilizer by banding or hole application; 30% of nitrogen fertilizer should be used as base fertilizer, and 70% should be applied as topdressing in 2 split applications at the rosette stage and early head-forming stage combined with irrigation. Note that potassium fertilizer should be applied as topdressing in the early heading stage, accounting for about 50% of the total potassium applied.