Cultivation techniques of Sweet Potato

Sweet potato is rich in protein, starch, pectin, cellulose, amino acids, vitamins and a variety of minerals, known as "longevity food". The sugar content is up to 15% and 20%. It has the effects of anti-cancer, protecting the heart, preventing emphysema, diabetes, losing weight and so on. Li Shizhen's Compendium of Materia Medica in the Ming Dynasty recorded the words "sweet potato to replenish deficiency, strengthen spleen and appetizer, and strengthen kidney yin", and said that people in the sea lived a long life. Sweet potato is regarded as a good medicine in traditional Chinese medicine.

Seedling raising method

Sweet potato seedlings need to be raised 2 months before transplanting, that is, spring potato seedlings begin in late January, autumn potato seedlings in mid-late June, and early winter potato seedlings in the first and middle of August. One-time seedling can be used, or it can be propagated in stages.

Seed selection, seedling purification and rejuvenation are carried out every year. To select seeds in areas free of virus and scab, and in fields with the same varieties, select medium-sized seed potatoes with long, uniform, furrow-free, straight, smooth skin, without disease and insect spots and scars as seeds, soak 5~10min with 1.0% cupric sulfate solution or 2% sodium hydroxide solution before planting, or soak seed potatoes with biological agents allowed for organic production such as Bt and Beauveria bassiana for 2 hours, and it is best to propagate virus-free seedlings in a screen greenhouse.

Nursery bed base fertilizer should be fully applied, generally every 667m2 self-retting organic fertilizer 500~1000kg, mineral potassium and magnesium fertilizer 50kg. Disinfect the seedbed or the shed with stone-sulfur mixture or lime before planting.

Seedling stage management

During the seedling period, the sweet potato is fertilized timely according to the seedling condition, and the fertilizer is used with bio-organic fertilizer certified by organic or approved by the organic certification institution (NPK total nutrient content ≥ 6%, organic matter content ≥ 40%). The total amount of topdressing during the seedling period is generally 250kg per 667m2. In the first "red bud" stage, thin fertilizer and water are generally applied, and when the seedling height is 10~13cm, the second topdressing can be carried out. After each fertilization, the seedlings should be poured with clean water to prevent the fertilizer from adhering to the seedlings and causing the phenomenon of burning seedlings.

Soil cultivation can be divided into 2 to 3 times, seedling height 10cm, can be carried out for the first time, 7 days for the second time, co-culture soil 3~5cm. It is best to mix charred mud ash or rotten compost with fertile loose fine soil and sprinkle it evenly into the seedbed. Soil cultivation can be combined with the application of liquid fertilizer, so that the soil can be cultivated first and then fertilized, so that the soil and the base of the seedling can be closely combined to facilitate early and multiple new roots.

After seeding, Bt and other organic production permitted biological agents and 300x tea bran water were sprayed every 15 days, plant ash was sprinkled once, and sex hormone traps were put around the seedling bed or outside the seedling shed.

Nursery bed management should also pay attention to heat preservation, moisturizing, ventilation and other measures, mainly temperature. Before emergence, the grass curtain should be covered at night to keep the bed temperature 25: 35 ℃. The temperature after emergence should be controlled at 20: 25 ℃. It is necessary to prevent the seedlings from burning at high temperature, such as the temperature in the film exceeds 30 ℃, ventilation and heat dissipation in time to prevent seedling burning. Do a good job of heat preservation when the cold wave comes.

Seed potatoes are generally not watered before emergence to facilitate high temperature germination, disease prevention and seedling emergence. If the seedling bed is too dry, spray water on the seedling bed with a sprayer. Attention should be paid to the humidity of the seedling bed after emergence. When the seedling bed is white, it should be watered in time, moisten the bed soil and sprinkle thin fertilizer water to promote the growth of potato seedlings; when the seedling bed is too wet, remove the film and ventilate in time.

Fertilizer and water management

The demand of sweet potato for nitrogen, phosphorus and potassium varies with different growth stages. Nitrogen fertilizer was absorbed more in the stem and leaf growth period, less in the root expansion period, less in the stem and leaf growth stage, and more in the root expansion period, while the absorption of potassium fertilizer was more than nitrogen and phosphorus from planting to harvest, especially in the root expansion stage. Therefore, the fertilization of sweet potato should be carried out around this characteristic, N ∶ P ∶ Kang 5V 620. It is best to use soil testing formula fertilization technology.

The organic cultivation of sweet potato forbids the application of any chemical fertilizer, mainly based on base fertilizer, and the general amount of base fertilizer accounts for 60%-80% of the total fertilizer application.

After transplanting seedlings alive, biogas liquid or fully mature thin manure water was applied once combined with seedling supplement, which was used as seedling fertilizer. The second time is in the sweet potato fruiting period, that is, about 60 days after planting in spring and autumn and 70 days after planting in winter. Potato fertilizer is mainly potash fertilizer, generally applied self-made organic fertilizer (or organic certified organic fertilizer) 500kg, plant ash 250kg or mineral potassium magnesium fertilizer 25kg every 667m2. Generally, the application method is to break both sides of the ridge by ploughing, or to open a small ditch at the waist of the ridge with a small hoe, and then mix the fertilizer and probiotics evenly for strip application. After application, one watering should be carried out to promote its fertilizer effect as soon as possible. At the same time, fertilization can be combined with artificial weeding to cultivate soil.

After watering the seedlings during planting, the sweet potato began to branch and drag vines 30-40 days after planting, and the water demand increased. In case of drought, timely watering can be done by furrow irrigation, but the amount of irrigation should not exceed the ridge height of 1 and 2. On the whole, it is appropriate for water management to master the basic moisture of the soil. If there is a rainy day, it should be drained in time to prevent stagnant water from causing potato seedlings to grow, resulting in the phenomenon that only long firewood roots do not bear potatoes.