the average yield of sweet potato is 35kg per mu in spring and 25kg per mu in summer. Growth period: the growth period of spring potato is 16-2 days, and that of summer potato is about 11-12 days. According to the growth characteristics of Hongchun in the field and its relationship with climate conditions. Early stage (from planting seedlings to sealing pots). Spring potato lasts about 6-7 days, and summer potato lasts about 4 days. At this stage, the growth of stems and leaves is slow, and the root system develops rapidly, which is mainly the period of growing fiber roots. Mid-term (from pot sealing to the peak of stem and leaf growth). Spring potato lasts about 5 days, and summer potato lasts about 3 days. At this stage, the tuberous roots expand slowly and the stems and leaves grow fast, which is a period of mainly growing stems and leaves. Late stage (from stem and leaf decline to harvest). Spring potato is after late August, and summer potato is after early September. This period is the main period of root swelling. Growth environment: 1. Temperature Sweet potatoes like temperature and are afraid of cold. When they are planted, they will not root when the ground temperature is 5-1 cm, 5 days at 15℃, normal at 17-18℃, 3 days at 2℃ and only one day at 27-3℃. When the temperature is 25-28℃, the stems and leaves grow fast, and when the temperature is above 3℃, the stems and leaves grow faster, but the tuber expands slowly. Above 38℃, the respiratory consumption is high, and the stems and leaves grow slowly. Below 2℃, the stems and leaves grow fast, and at 15℃, they stop growing. If the temperature below 1℃ lasts too long, they will encounter frost and die. The higher the ground temperature is between 21-29℃, the faster and more tuberous roots are formed, but the potato tubers are smaller. The ground temperature of 22-24℃ is favorable for the formation of tuberous roots. The ground temperature of 2-25℃ is most suitable for root swelling. When it is lower than 2℃ or higher than 3℃, the root swelling is slow. When it is lower than 18℃, some varieties stop swelling. When it is lower than 1℃, it is easy to suffer from cold injury. When it is -2℃, the root swelling is frozen. The larger temperature difference between day and night during root tuber expansion is beneficial to root tuber expansion and nutrient accumulation. Second, the light sweet potato likes light. In the case of sufficient light, the leaves are thicker, the leaves are longer, the stems and vines are strong, the conducting tissues of the stems are developed, and the yield is higher. If the light is insufficient, the leaves will be yellow, with many fallen leaves, short leaf age, slender stems and vines, underdeveloped transport tissues, less transport of organic nutrients formed by assimilation to root tubers and low yield. Long light exposure time per day is beneficial to the growth of stems and leaves, and the stems and vines become longer and the number of branches increases. Exposure to light for 12.5-13 hours a day is more suitable for root swelling. Exposure to light for 8-9 hours a day is beneficial to bud flowering, but not suitable for root swelling. Third, the moisture sweet potato is a drought-tolerant crop, but too much water is not conducive to increasing production. Sweet potato is afraid of flooding, especially after the potato is planted, which has a great influence on the yield. The uneven growth rate inside and outside the root tuber is caused by the uncertainty of soil moisture, and the phenomenon of skin cracking often occurs. In a word, sweet potato is afraid of both waterlogging and drought. In order to obtain high yield of sweet potato, appropriate irrigation should be given according to specific conditions, and drainage should be thoroughly carried out in time. In dry land, intertillage should be strengthened to preserve moisture. Fourth, nutrient sweet potato has strong ability to absorb fertilizer and is barren, but it must be fully fertilized to achieve high yield. Besides nitrogen, phosphorus and potassium, sulfur, iron, magnesium and calcium also play an important role. Among the three elements, sweet potato requires the most potassium, followed by nitrogen and the least phosphorus. According to analysis, every 1 Jin of sweet potato contains 3.5 Jin of nitrogen, 1.75 Jin of phosphorus and 5.6 Jin of potassium. Therefore, increasing the application of potassium fertilizer and timely and appropriate application of nitrogen and phosphorus fertilizer can significantly increase production. The sandy loam and sandy soil with deep soil layer, rich organic matter, loose, good ventilation and drainage performance are better. When the soil is sticky, the root bark is not good and rough, the potato shape is irregular, the yield is low, and it is not resistant to storage. However, sandy loam and sandy soil generally have low fertility and poor water retention capacity, so we should gradually improve the soil fertility through fertilization and other measures to obtain high yield. Sweet potato is more resistant to acid and alkali, and its PH value is about 4.5-8.5, but 5.2-6.7 is suitable. When the soil salt content exceeds .2%, sweet potato should not be planted.