Need fertilizer characteristics. The yam has a long growth period and requires a large amount of fertilizer, especially organic fertilizer with a long fertilizer 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 stage of growth, due to the low temperature and slow release of organic nutrients, it is advisable to supply an appropriate amount of available nitrogen fertilizer to promote the growth of stems and leaves. The growth of tubers in the middle and late growth period is in rapid increase, and large amounts of nutrients, especially phosphorus and potassium fertilizers, need to be absorbed. Special attention must be paid to prevention. Fat and premature aging. The yam is a chlorine-tolerant crop. Excessive chloride ions in the soil will affect the growth of yam, which is characterized by strong growth of vines, reduced tuber yield, reduced quality, fragile and brittle, and impatience for storage and transportation. Therefore, it is not appropriate to use chlorine-containing fertilizers.
Fertilization technology. The yam fertilization is generally based on basal fertilizer supplemented by top dressing. Basal fertilizer is mainly composed of high-quality farmyard manure and compound fertilizer that are fully decomposed and can also be applied with nitrogen, phosphorus and potassium. The focus of topdressing is in the period of tuber enlargement. It is necessary to apply appropriate amount of available fertilizer to the plant to promote health and prevent premature decline. Maturity of farmyard manure 2000-4000 kg per acre, the same amount of compound fertilizer (18-18-18) 60-80 kg (before the application of the two fully mixed), or organic fertilizer 2000 kg, 25 kg of urea, diammonium phosphate 25 kg, 30 kg of potassium sulfate. The basal fertilizer was spread evenly throughout the field before planting. After application, the fertilizer was ploughed into a 30 cm plow layer. The principle of skillful top-dressing is "early weight, medium-term stability, and late-term anti-aging."
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