Appropriate amount of nitrogen fertilizer applied to Chinese cabbage

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The fertilization of Chinese cabbage should achieve the dual goal of balancing high yield and quality. The nutrient characteristics of Chinese cabbage is 1:0.5:1.2 for NPK, indicating that its potassium requirement is greater than the nitrogen requirement. In actual production, only the application of nitrogen fertilizer is generally paid attention to, and the balance supplement of potassium fertilizer is often neglected. In view of the fertilization status of Chinese cabbage last year, it is clear that there are several points of attention in this year's fertilization: the primary problem is that the application of nitrogen fertilizer should be appropriate. How much nitrogen fertilizer is appropriate? Practice has proved that the production of 1000 kg of fresh vegetables needs to absorb about 2.0 kg of pure nitrogen from the soil. The production of 10,000 kg of fresh vegetables requires 22 to 25 kg of nitrogen. The nitrogen required for Chinese cabbage can be derived from soil, organic fertilizer and fertilizer. . The application amount of the chemical nitrogen fertilizer should be appropriately reduced under the condition of applying a large amount of organic fertilizer. Applying appropriate amount of nitrogen fertilizer can help the growth of Chinese cabbage, which is beneficial to photosynthesis, and is the key to achieving high yield of Chinese cabbage. In some remote areas, there may be insufficient supply of nitrogen fertilizer, the leaves are thin and pale, and the organization is rough, which not only affects the yield but also the quality. However, at present, the actual nitrogen application rate in most areas of production exceeds the demand, while the excessive application of nitrogen fertilizer is not only rich in the outer leaves of Chinese cabbage, poor in core, low in yield and quality, but also high in leaf water content and not resistant to storage after harvest. It is prone to decay and is susceptible to pests and diseases in the later stages of growth. Therefore, in addition to the appropriate amount, the period of use of nitrogen fertilizer is also important. In the whole growth period of Chinese cabbage, the nitrogen uptake at different stages is different. Seedling period is very small, accounting for about 2% of the total. The rosette period increases to about 28% of nitrogen, and the nitrogen uptake during the core period is the highest, accounting for about 70% of the total. Therefore, the application of nitrogen fertilizer should be applied in several stages, reflecting the light weight before and after. Chinese cabbage has a longer growth period, and fertilization management should be applied to the base fertilizer. In terms of topdressing application, Chinese cabbage must be controlled from water control (mainly nitrogen control) from seedling stage to sapling stage, except for special circumstances. Generally, in the rosette period, seedlings should be planted. First, the assimilated organs (outer leaves) grow vigorously, and secondly, they promote root growth and undercut, laying a foundation for rapid growth and absorption of nutrients and water in the later period. The first time the topdressing was in the key moment of the rosette period. It is advisable to apply quick-acting nitrogen and potassium fertilizers, and at the same time, watering, water and fertilizer will enter the core period. The second top dressing of Chinese cabbage is in the early and middle stages of the core, mainly applying nitrogen fertilizer, up to two times, to control nitrogen. After the core of the package, the nitrogen fertilizer was stopped.
Second, increase the proportion of phosphorus and potassium fertilizer application. The addition of potassium fertilizer in base fertilizer and top dressing is conducive to the cabbage and disease resistance of Chinese cabbage. In the early stage of the topping, it is necessary to pay attention to the application of potassium fertilizer. If the supply of phosphorus and potassium fertilizer is insufficient in the cabbage, it is not easy to form a ball. At present, in the production of vegetables, the application of potassium fertilizer is often ignored. The appropriate potassium application rate is generally 12 kg of potassium chloride per acre or 16 kg of potassium sulfide. The application method is preferably applied twice by base fertilizer and top dressing. The base fertilizer is applied to the bottom of the hole at the time of planting, and the top dressing is carried out after the end of the seedling stage, combined with the application of nitrogen fertilizer and irrigation.
Third, we must pay attention to the supply of calcium fertilizer. The application of superphosphate by base fertilizer supplements calcium nutrition, which is beneficial for preventing the occurrence of "dry heart" disease in Chinese cabbage. Chinese cabbage is a calcium-loving crop, and calcium deficiency, especially excessive nitrogen application, can cause dry heart disease. Controlling nitrogen fertilizer and supplementing calcium nutrition is an important technology to prevent the "dry heart" disease of Chinese cabbage. Calcium supplementation method, in addition to soil application of calcium fertilizer, can also be foliar supplementation method, spraying 0.1% ~ 0.3% calcium chloride or calcium nitrate, or spraying calcium sugar alcohol and amino acid calcium, Spray 2 to 3 times during the rosette period.
Author: Cao Yiping (The author is a senior consultant Sinochem fertilizer, China Agricultural University)
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