High-Yield Sweet Potato Cultivation Techniques Tutorial, Latest Methods Explained in Detail

Sweet potato is a crop with high and stable yields. It has the characteristics of wide adaptability, strong stress resistance, drought tolerance, tolerance of poor soil, and relatively few pests and diseases. When planted in places with good water and fertilizer conditions, the yield per mu can generally reach 2000--3000 kg for spring sweet potatoes. However, due to differences in natural conditions and cultivation levels, the yield levels are also very uneven. In order to give full play to the yield-increasing potential of sweet potato and achieve high quality and high yield, the following high-yield cultivation techniques for sweet potato are specially proposed.

Seedbed Raising of Seedlings

Promoting sprouting and raising seedlings is an important part of the entire off-season cultivation. The seedling raising time should be appropriately advanced to mid-February, when seed potatoes are moved into a protected seedbed for seedling raising. The seedbed should use double-layer film protection. Arrange the seed potatoes neatly, cover with a layer of fine soil, then lay a layer of plastic film flat on top, and then build an arch frame and cover with another layer of film to increase the seedbed soil temperature. Promptly punch holes in the flat-laid plastic film to guide out the seedlings, so as to avoid burning the tender seedlings during high temperatures on sunny days. In the first month of the seedbed, spray water once every 7 days. After 1 month, spray water and fertilizer plus New High-Lipid Film twice a week to prevent pathogen infection and protect the seedlings so they grow strong. (When the plants reach 15 cm in height) cut a batch every 7-10 days. Starting from the first cutting, spray water and fertilizer twice a week, appropriately increasing the concentration, to ensure nutrient supply for the regenerated seedlings.

Apply Sufficient Base Fertilizer

Choose loam soil and select sandy plots. In early spring, while plowing, apply 2-3 tons of farmyard manure, 15 kg of urea, and 20 kg of phosphate fertilizer per mu.

Plastic Film Mulching

Plastic film mulching can increase temperature and preserve moisture, while also improving the physical and chemical properties of the soil and increasing the diurnal temperature difference in the soil. For planting sweet potatoes, a high-ridge mulching method with double-row staggered planting can generally be used. The whole spacing is 60 cm, the mulched surface is 50 cm, the small row is 40 cm, plants are staggered between rows, plant spacing is 33 cm, and about 4000 plants are left per mu. The ridge height should be moderate. If the planting period is too dry, flat covering and flat planting can be used to facilitate seedling growth.

Plant Early at the Right Time

Plant early at the right time and maintain a reasonable dense spacing: mid-April is the suitable period for transplanting seedlings. At this time, the early spring temperature has generally warmed up and become basically stable. The suitable planting period is when the 10 cm soil temperature reaches above 15°C after the late frost, and then planting can begin. Plow and expose the soil early in the previous winter or early in the current year, and then form ridges and prepare beds when planting. The bed width is 50 cm. In early to mid-April, according to the seedling emergence speed in the seedbed, cut seedlings successively for transplanting. Use the line flat-planting method to increase the number of nodes of the sweet potato seedlings inserted into the soil, thereby increasing the number of tubers set. Insert 3500-4000 plants per mu, with a plant spacing of about 33 cm. The transplanting time should not exceed April 20, otherwise the harvest time will be delayed and will affect the transplanting season of the subsequent late rice.

Planting early at the right time is the key to increasing sweet potato yield. Under suitable conditions, the earlier the planting, the longer the growth period, the earlier the tubers are set, the more tubers are set, the longer the tuber roots expand, and the higher the yield and better the quality. If planting is too late, the growth period is shortened, the sweet potatoes are few and small, and the yield is low and the quality is poor. The suitable planting period is when the 10 cm soil temperature reaches above 15°C after the late frost (around mid-April). Plastic film mulching can appropriately advance this, and then planting can begin. In order to improve planting quality and ensure vigorous seedlings, when planting, remove “old hard seedlings” and weak or diseased seedlings, and select strong seedlings for transplanting. When planting, it is best to grade large and small seedlings and plant them separately so that they grow evenly. To control sweet potato black spot disease, use a 1000-fold solution of 50% thiophanate-methyl to soak the base of the seedlings for 2-3 cun for 10 minutes. Sweet potatoes should be planted shallowly on the basis of ensuring survival. The transplanting depth is generally 5-6 cm. When transplanting, cover the soil tightly and keep the depth consistent, so that the leaves are exposed above the ground and do not get covered with mud when watering. The seedlings should emerge straight, and the seedlings should not be exposed too long, so as to prevent strong winds from whipping the seedlings and affecting survival.

Field Management

1. Management during the root establishment and seedling recovery stage

The root establishment and seedling recovery stage lasts from after planting, when new roots grow, until tuber roots begin to form, about 1 month. After sweet potatoes are planted, check for and fill in missing plants promptly to ensure a full stand. After planting, if there is severe drought, promptly water to help seedling recovery and promote root establishment and survival. Generally, after transplanting, water once, and thereafter cultivate once every 10-15 days to loosen the soil, raise temperature, and eliminate weeds. Spray New High-Lipid Film at the appropriate time to promote rapid plant growth and root formation.

2. Management during the branching and tuber-setting stage

30-40 days after transplanting, as the temperature rises, stem and leaf growth accelerates, and tuber roots continue to form and expand. Water and fertilizer management should be strengthened promptly. If drought occurs, apply 5-8 jin of urea per mu with irrigation water. After watering, cultivate and loosen the soil early to preserve moisture.

3. Management during the stage of vigorous stem and leaf growth and tuber root expansion

From the first ten days of July to the last ten days of August, during this period the stems and leaves grow vigorously and the tuber roots expand, and the leaf area index reaches its maximum. Generally during this period, it is necessary to achieve both promotion and control, with control within promotion and promotion within control. This period coincides with the rainy season, with high temperatures and rapid plant growth. To prevent excessive vine growth, use a 50 PPM paclobutrazol solution plus Diguo Zhuangdiling and spray evenly in the field, with the leaf surface fully covered by the solution but not dripping as the ideal. This can promote fruit development and make sweet potatoes high-quality and high-yield. During this period, the underground tuber roots expand rapidly. If summer drought occurs, watering is needed, but the amount of water should not be too large. To promote tuber expansion, use one bag (12) g of expansion agent per mu mixed with 15 kg of water and spray once every 7-10 days, for two consecutive sprays.

4. Management during the stage of stem and leaf decline and tuber root expansion

After mid-to-late August, in the later growth stage of sweet potato, stems and leaves slow their growth until they stop. Nutrients are transported to the tuber roots, and the growth center shifts from aboveground to underground. In management, it is necessary to protect the stems and leaves, maintain normal physiological functions, and promote rapid tuber root expansion. Management measures should ensure soil moisture content at 60-70% of the maximum field water-holding capacity. If the weather is dry for a long time without rain and the soil is dry, the stems and leaves will prematurely senesce, affecting the formation and accumulation of carbohydrates and causing yield reduction. Therefore, water lightly in a timely manner, but do not water within 20 days before harvesting sweet potatoes. If autumn waterlogging occurs, drain promptly to prevent hard core and rot. Around End of Heat, sweet potato leaves enter the vine-return stage. To prevent premature senescence, prolong and enhance photosynthesis in the leaves, and promote tuber enlargement, carry out foliar fertilization. Apply half a jin of potassium dihydrogen phosphate per mu mixed with 30-40 kg of water plus 800-fold New High-Lipid Film solution and spray once every 15 days for a total of two sprays. The effect is better if used together with expansion agent.

5. Pinching the Top

When the main stem of the sweet potato grows to 50 cm, choose sunny weather in the morning and pinch off the terminal bud. When branches grow to 35 cm, continue to remove the terminal buds. This method can inhibit excessive growth of stems and vines, avoid nutrient consumption, promote tuber root expansion, and increase yield by 20%-30%.

6. Fertilizer Application Through Cracks

When sweet potatoes enter the tuber root expansion period, cracks will appear in the surface soil. At this time, use 750-1000 kg of clear water and manure fertilizer per mu, add 500 g of potassium dihydrogen phosphate (or 5 kg of superphosphate and 50 kg of plant ash, soaked and filtered separately in water), mix into the manure fertilizer, and pour along the cracks in the morning or evening. After pouring, fill the cracks with soil, and at the same time spray Diguo Zhuangdiling to prevent deformed fruits and cracked fruits, which can increase yield by 20%-30%.

Harvest at the Right Time

The tuber roots of sweet potato are asexual vegetative organs and have no obvious maturity standard or harvest period. However, the timing of harvest is closely related to sweet potato yield, seed retention, storage, processing and utilization, and crop rotation. Harvesting too early will reduce yield, and harvesting too late will be affected by low-temperature chilling injury. The suitable harvest period for sweet potatoes is generally to begin digging when the air temperature drops to 15°C, and to finish digging when the air temperature is above 10°C or the soil temperature is above 12°C, that is, before the killing frost. Generally, digging is completed around Cold Dew.