Fertilizer requirement characteristics and fertilization techniques for High yield of Chinese Yam

The characteristic of fertilizer need. Chinese yam has a long growth period and needs a large amount of fertilizer, especially the organic fertilizer with long effect. As the formation of tubers is accompanied by the accumulation of starch and other substances, the demand for phosphorus and potassium is relatively large. In the early growth stage of Chinese yam, due to low temperature and slow release of organic nutrients, it is appropriate to supply an appropriate amount of available nitrogen fertilizer to promote stem and leaf growth; the growth of tubers increases rapidly in the middle and later stage of growth, which needs to absorb a large amount of nutrients, especially phosphorus and potassium fertilizer. special attention should be paid to prevent early senescence due to lack of fertilizer. Chinese yam is a chlorine-free crop. Excessive chloride ion in soil will affect the growth of Chinese yam, such as exuberant vine growth, reduced tuber yield and quality, fragile and fragile, not resistant to storage and transportation. Therefore, it is not suitable to apply chlorine-containing fertilizer. Fertilization technology. The fertilization of Chinese yam is mainly based on base fertilizer and supplemented by topdressing. The base fertilizer is mainly fully mature high-quality farm fertilizer and compound fertilizer, and can also be applied in the proportion of nitrogen, phosphorus and potassium. The focus of topdressing is in the tuber expansion period, and appropriate amount of available fertilizer should be applied according to the plant growth to promote growth and prevent premature senility. 2000-4000 kg of rotten farm manure, 60-80 kg of compound fertilizer (18-18-18), or 2000 kg of organic fertilizer, 25 kg of urea, 25 kg of diammonium phosphate and 30 kg of potassium sulfate were applied per mu. The base fertilizer is spread evenly throughout the field before soil preparation, and after application, the fertilizer is ploughed into the 30cm plough layer. The principle of skillfully chasing fat is "heavy in the early stage, stable in the middle stage, and preventing premature senility in the later stage".