How to grow sweet potatoes to get high yield?

Sweet potato is a kind of whole grain that many friends like to eat. It is very nutritious and rich in fiber. Sweet potato is a relatively high-yield crop, so as long as you master the planting method, high yield is not a problem. Let’s learn together how to grow sweet potatoes to achieve high yields.

1. Sweet potato seedling raising technology

Sweet potato seedling raising should be carried out two months before transplanting, and can be done all at once or in batches.

Selection and seedling cultivation are required every year for purification and rejuvenation. When selecting seeds, you should choose fields with consistent varieties in areas free of virus diseases and scab, and select medium-sized seed potatoes that are long, uniform, straight, without ridges and grooves, smooth in skin, and free of disease, insect spots, and scars as seeds. Before planting, the seed potatoes can be soaked in 1.0% copper sulfate solution or 2% sodium hydroxide solution for 5 to 10 minutes, or in biological agents allowed in organic production such as Bt and Beauveria bassiana for 2 hours. The best practice is to grow virus-free seedlings in insect-free conditions in a mesh greenhouse .

The base fertilizer of the seedbed should be sufficient. Generally, 500 to 1000 kg of self-fermented organic fertilizer and 50 kg of mineral potassium and magnesium fertilizer are applied per 667 square meters. Before sowing, use lime sulfur or lime to disinfect the seedbed, or sterilize the greenhouse.

2. Seedling Management

During the sweet potato seedling period, topdressing should be applied in a timely manner according to the condition of the seedlings, using organically certified or organically certified bio-organic fertilizers (total NPK nutrient content ≥ 6%, organic matter content ≥ 40%). The total amount of topdressing during the seedling period is generally 250 kg per 667 square meters. The first time is to apply thin fertilizer water during the "red bud" stage; when the seedlings are 10 to 13 cm tall, the second topdressing is carried out. After each fertilization, rinse the seedlings with clean water to prevent fertilizer from sticking and causing seedling burn.

Soil accumulation can be carried out in 2 to 3 times. The first soil accumulation is carried out when the seedlings are about 10 cm tall, and the second soil accumulation is carried out after 7 days. The total soil accumulation is 3 to 5 cm. It is best to use fertile, loose fine soil mixed with burnt mud or well-rotted compost and spread it evenly in the seedbed. Soil accumulation can be combined with the application of liquid fertilizer. First, soil accumulation and then fertilization will allow the soil and the base of the seedlings to be tightly combined, which is conducive to the early and frequent growth of new roots.

After sowing, spray Bt and other biological agents with organic production approval and 300 times tea bran water every 15 days, and sprinkle wood ash once; and place sex hormone traps around the seedbed or outside the seedling shed.

Seedbed management also requires attention to measures such as insulation, moisture retention, and ventilation, with temperature control being the main focus. Before germination, cover the seeds with straw mats at night to keep the bed temperature between 25 and 35°C. After germination, the temperature should be controlled at 20 to 25°C to prevent high temperature from burning the seedlings. If the temperature inside the film exceeds 30℃, ventilate and dissipate heat in time to prevent seedlings from burning. When a cold wave comes, you must keep warm.

Seed potatoes are generally not watered before they emerge, in order to facilitate high temperature germination, disease prevention and emergence. If the seedbed is too dry, you can use a sprayer to spray clean water on the seedbed. After the seedlings emerge, pay attention to the humidity of the seedbed. When the seedbed turns white, water it in time, moisten the soil and sprinkle dilute fertilizer water to promote the growth of potato seedlings. When the seedbed is too wet, remove the film and ventilate it in time.

3. Fertilizer and water management

Sweet potato's demand for nitrogen, phosphorus and potassium varies with the growth period. Nitrogen fertilizer is absorbed more during the stem and leaf growth period, and less during the root expansion period; phosphorus fertilizer is absorbed less in the middle of the stem and leaf growth period, and more during the root expansion period; potassium fertilizer is absorbed more than nitrogen and phosphorus from planting to harvest, especially during the root expansion period. Therefore, sweet potato fertilization should be based on this characteristic, N:P:K=5:6:20. It is best to use soil testing and formula fertilization technology.

It is prohibited to use any chemical fertilizers in organic sweet potato cultivation. Base fertilizer is the main fertilizer. Generally, the amount of base fertilizer accounts for 60% to 80% of the total fertilizer application. Base fertilizer is applied in combination with land preparation and ridge forming.

After the transplanted seedlings are alive, apply biogas slurry or fully decomposed thin manure water as a fertilizer to promote the growth of seedlings. The second time is during the sweet potato tuber formation period, which is about 60 days after planting in spring and autumn, and about 70 days after planting in winter, when topdressing fertilizer is applied. Potato fertilizer is mainly potassium fertilizer. Generally, 500 kg of homemade organic fertilizer, 250 kg of wood ash or 25 kg of mineral potassium-magnesium fertilizer are applied per 667 square meters. The application method is to use a plow to break open the sides of the ridge, or use a small hoe to make a small ditch on the waist of the ridge, and then mix the fertilizer and probiotics and apply it in strips. Watering should be done after application to promote the fertilizer effect as soon as possible. At the same time, after fertilizing, soil can be cultivated in combination with manual weeding.

After the sweet potatoes are watered when they are planted, they will start to branch and trail vines 30 to 40 days after planting, and their water demand will increase. If there is drought at this time, water them in time. You can use furrow irrigation, but the amount of water should not exceed 1/2 of the ridge height. Overall, water management should keep the soil basically moist. If it rains, drainage should be carried out in time to prevent water accumulation from causing the potato seedlings to grow too tall, resulting in only roots growing but no potatoes.

4. Field Management

1. Management from the rooting and seedling stage to the branching and tuber formation stage

This period is the stage when sweet potatoes take root and turn green. They require little water and consume little nutrients. Therefore, the focus is on checking the seedlings, filling in the gaps and preserving the seedlings. Generally, check the seedlings and replant within 5 days after transplanting, and keep the soil moist to increase the survival rate of potato seedlings. About 15 days after transplanting, apply seedling fertilizer in time according to the growth trend (about 20% of the total amount of nitrogen and potassium fertilizers), and apply more fertilizer for the replanted seedlings.

2. Long-term management from the branching and tuber formation stage to the full growth of stems and leaves

This period is the stage of branching, seedling growth, root growth and tuber formation, and the focus is on controlling vines and promoting branching. Before 40 to 45 days after planting, the water requirement is not much, just keep the soil moist in the field. After the stems and leaves cover the ridges, the water demand is the highest, and the soil water holding capacity should be maintained at 70% to 80% of the maximum water holding capacity; therefore, "running water" should be irrigated as appropriate.

3. Management from the period of full growth of stems and leaves to the period of tuber expansion

This period is an important time for tuber enlargement and sufficient accumulation of nutrients in the tubers. The key is to maintain a balanced growth period between the above-ground and lower parts of the sweet potato through water management to prevent excessive growth caused by excessive water. Therefore, we must pay attention to dredging ditches, draining water during floods and irrigating water during droughts, and pay attention to pest control.

4. Management from tuber expansion to harvest

This period is mainly an important period for the accumulation of starch in tubers. During the tuber's growing period, from the peak of stem and leaf growth until maturity, the growth of basal leaves gradually slows down, the leaf color becomes lighter, and then growth stops. The growth center turns to tuber growth. For fields where leaves are yellowing and aging prematurely, apply vine-growing fertilizer in time. Generally, 15 to 20 dan of manure water is applied, and the method is to pour it along the cracks on the top of the ridge. Or use 200 grams of potassium dihydrogen phosphate, 500 grams of urea and 40 kilograms of water for foliar spraying twice. At the same time, ditches should be cleared and waterlogged to prevent potato rot. Or around 90 days after planting, if the growth of the aboveground part is weak, use a small amount of nitrogen fertilizer (about 2 kg of urea) per mu by watering or spraying to prevent premature aging. At the same time, pay attention to timely irrigation during drought. Generally, no irrigation is applied 20 to 30 days before harvest to facilitate the harvest and storage of sweet potatoes.

5. Harvest at the right time

The critical temperature for the growth of sweet potato tubers is 15℃. Frost damage will occur below 9℃. It is advisable to start harvesting when the temperature drops to 15℃ to 12℃.

The above is an introduction to the key points of sweet potato cultivation . As long as you master the field management work, you can achieve good yields when cultivating sweet potatoes.