Detailed Explanation of Pollution-Free Fertilization Technical Specifications for Yam Cultivation

① Propagation technology: Yam propagation is divided into two types: sexual propagation and asexual propagation. Sexual propagation is mainly used for crossbreeding to obtain new high-yield, high-quality variety types; because it requires a long time, it is generally not suitable for use in production. Asexual propagation includes tuber cutting propagation methods, terminal bud propagation methods, etc. Fertilizer and water management techniques are the same as for field cultivation.

② Field cultivation fertilization technology: a. Land preparation and fertilization, timely planting: Yam absorption roots enter the soil relatively shallowly while tubers enter the soil relatively deeply, therefore, a sandy loam or loam soil with deep, loose soil layers and no continuous cropping within 3 years must be selected, deeply plowed more than 35 cm in the previous winter, and planted in high beds or furrow ridges after spring begins. Since the main absorption root system of yam is distributed in the upper soil layer, base fertilizer is applied shallowly in the surface soil layer, adopting the method of first planting seed tubers, then turning the soil and applying fertilizer. For base fertilizer, dry manure, plant ash, or farmyard manure mixed with soil is suitable. Manure should be decomposed first, generally applying 30000-60000 kg/hectare, applying urea 300-375 kg/hectare, superphosphate 225 kg/hectare, potassium sulfate 375-525 kg/hectare. In areas with a relatively short frost-free period, in order to extend its field growth period and improve yield and quality, the method of raising seedlings and transplanting can be adopted, using protective facilities for seedbed seedling raising, then timely planting into the field. b. Skillful application of topdressing: In the early stage, yam mainly grows aboveground stems and leaves, underground stems grow relatively slowly, and fertilizer demand is also relatively small. Therefore, from sowing or transplanting until plant establishment, decomposed manure can be applied in large amounts, generally applying one application of dilute manure urine at about 15000 kg/hectare from the time of full seedling emergence or after transplanted plants survive. Afterward, apply once every 20-30 days, each time applying decomposed manure urine fertilizer 15000-22500 kg/hectare or ternary compound fertilizer 225-300 kg/hectare in furrows. After the plant buds appear, while the underground tuber rapidly elongates, it also gradually enters a period of expansion, thickening, and weight increase, and fertilizer demand increases sharply. At this time, a mixed liquid of relatively concentrated human manure urine and cake fertilizer 30000-60000 kg/hectare or three-element compound fertilizer 600-750 kg/hectare should be heavily applied. This topdressing is the key fertilizer application with the greatest impact on tuber yield. Later, when the stems and vines cover the trellis, if fertilizer deficiency is found, another topdressing can be applied, with a smaller amount than the previous application. The last application is 40 days before harvest, observing plant growth conditions, applying fertilizer once to improve tuber yield and quality. After Frost's Descent, when aboveground stems and leaves turn yellow and withered, they should be harvested in time.