The ratio of nitrogen, phosphorus and potassium needed for Chinese cabbage is 1:0.5:1.2, and the demand for potassium is greater than the demand for nitrogen. In fact, farmers only pay attention to the application of nitrogen fertilizer in practical production, and neglect the application of potash fertilizer, resulting in a decline in yield and quality. Therefore, fertilization must grasp three principles.
First, the amount of nitrogen fertilizer should be applied. Mainly based on basal fertilizer, basal fertilizer combined with top dressing. Nitrogen is the main nitrogen fertilizer, and nitrogen, phosphorus, and potassium are combined to supplement trace elements. It is planned to produce about 4,000 kilograms of Chinese cabbage per acre, which requires 2,000 kg of organic fertilizer, 15-20 kg of pure nitrogen, 4-6 kg of phosphorus (P2O5), 14-20 kg of potassium (K2O), and 5,000 kg of mu. Organic fertilizer 3000 kg, pure nitrogen 18-23 kg, phosphorus (P2O5) 5-8 kg, potassium (K2O) 16-22 kg, organic fertilizer, phosphate fertilizer as base fertilizer, 30% nitrogen and potassium fertilizer as base fertilizer, and the remaining 70% Nitrogen and potassium fertilizers were traced once during the rosette period and before the center of filling. Excessive application of nitrogen not only leaves the outer leaves of Chinese cabbage to be hypertrophic, has poor package quality, has a low yield and quality, but also has large water content in the leaves, is not resistant to storage after harvest, is easily rotted, and is susceptible to pests and diseases in the late growth stage.
The second is to increase the proportion of phosphorus and potassium fertilization. Potassium is beneficial to Chinese cabbage's heart and disease resistance. If the supply of phosphorus and potassium is insufficient during the period of contracting Chinese cabbage, it will not result in ball-bearing. The appropriate amount of potassium is 16 kg of potassium sulfate per mu. And to sub-basal fertilizer and top dressing two applications: base fertilizer applied to the hole at the time of planting, top dressing is the end of the rosette seedlings, combined with topdressing nitrogen fertilizer and irrigation together.
The third is to add calcium. Cabbage is a hi calcium crop, calcium deficiency, especially excessive nitrogen easily cause "heartburn." Calcium nutrition is supplemented by base fertilizer application of superphosphate, which is very beneficial for preventing the occurrence of “heartburn†disease of Chinese cabbage. Controlling nitrogen fertilizer and supplementing calcium nutrition are the core technologies for preventing Chinese cabbage "dry heart" disease. Foliar application of 0.3%-0.5% calcium chloride or calcium nitrate (spray once every 10-15 days) can also be used to supplement calcium.
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