Growing sweet potato vines on trellises can increase yield
Last autumn, on the day we dug up the sweet potatoes, many onlookers came over, because they wanted to see just how the yield turned out after growing sweet potatoes on trellises. As soon as several piles were dug up, the onlookers were full of praise: “The trellised sweet potatoes have grown really well, large, uniform, and abundant in yield!”
This is the sweet potato trellis trial we carried out over the past two years. It targeted the biological characteristics of sweet potatoes, such as their love of light, fear of cold and shade, fear of waterlogging, relatively good drought tolerance, tendency to root readily, and easy tendency to grow leggy, and it solved the problem of vines growing without setting tubers during the growing period when vines are not lifted, with a notable yield-increasing effect. The trial methods and results are presented below:
Trial methods for sweet potatoes
1. Forming mounds. This can be done from after the soil thaws in early spring until late April. If mounds are formed after irrigating the field, they can be formed a few days before transplanting the vines, in order to preserve soil moisture. The base diameter of each mound is about 60 cm, the mound height is about 25 cm, and the spacing between mounds is 10 cm. While forming the mounds, add an appropriate amount of farmyard manure and special fertilizer for sweet potatoes. Generally, about 1,330 mounds can be formed per mu.
2. Transplanting vines. In the Tangshan area this is done in early May; in other areas, the transplanting time can be determined according to when the potato vines leave the hotbed. Select relatively sturdy potato vines without black roots, and plant 3 in each mound (in a triangular arrangement). If soil moisture is poor, the vines should be transplanted with water beneath them to ensure a full stand.
3. Loosening the soil and weeding. Loosen the soil and weed once every half month; in an ordinary year, doing this 3 times is enough, ensuring that no weeds grow beneath the potatoes.
4. Inserting the trellis. Begin inserting the trellis after the potato vines have grown to 60-80 cm. Use 2 m long bamboo poles, 3 per mound, inserted in a triangular arrangement, and tie them tightly and fix them at a point about 33 cm from the top of the poles. After the trellis is inserted, lift the potato vines up along the poles, one vine per pole, and tie the potato vines with soaked corn husks so that they grow upward. Check frequently; as the potato vines grow, tie them, and according to their growth, pinch off branches to control the vines, until they reach the top of the poles.
Trial results for sweet potatoes
Last year we set up 6 mounds on thin hillside soil, choosing variety 138. After autumn, the sweet potatoes were dug up and weighed: the trellised ones averaged 3 kg per mound, while the non-trellised ones averaged 1.4 kg per mound. This year we planted 33 mounds of trellised sweet potatoes, still choosing variety 138. Because the trial was in a pear orchard and was affected by tree shade, the yield per mound was slightly worse than last year: trellised sweet potatoes averaged 2 kg per mound, while non-trellised sweet potatoes averaged 0.65 kg per mound, making the yield-increasing effect even more notable.
Analysis of the reasons for increased sweet potato yield
1. Increased light and higher yield. After the sweet potato vines are trellised, they have ventilation and light, do not root randomly and consume nutrients, the area receiving light increases, and excessive growth can be prevented by pinching off branches.
2. Reduced damage. After sweet potatoes are trellised, the potato vines no longer need to be turned over, which reduces root damage, correspondingly increases growing time, and lays the foundation for a plentiful sweet potato harvest.
Note: Each new bamboo pole about as thick as a finger is calculated at 0.2 yuan, and generally can be used for 4-5 years.
Growing conditions for sweet potatoes
1. Temperature: Sweet potatoes like warmth and fear cold. At a soil temperature of about 10°C they do not develop roots; at 15°C they need 5 days to develop roots; at 17-18°C root development is normal; at 20°C they develop roots in 3 days; at 27-30°C they can develop roots in only one day. When the air temperature is 25-28°C, stems and leaves grow quickly; above 30°C, stems and leaves grow even faster, but the tubers expand slowly. Above 38°C, respiration consumes a lot, and stem and leaf growth is slow; below 20°C, stem and leaf growth is also fast; at 15°C growth stops; below 10°C, if it lasts too long or frost occurs, the stems and leaves die.
2. Light: Sweet potatoes like light. Under sufficient light, the leaves are darker in color, the leaf age is longer, the stems and vines are sturdy, the conductive tissue of the stems is well developed, and the yield is relatively high. If light is insufficient, the leaves turn yellow, more leaves fall, leaf age is short, the stems and vines are slender, the conductive tissue is not well developed, less organic nutrition formed by assimilation is transported to the tubers, and the yield is low.
3. Water: Sweet potatoes are a drought-tolerant crop, but too much or too little water is unfavorable for increasing yield. Sweet potatoes fear flooding, especially after tuber formation, when flooding has a great impact on yield. If the soil is alternately dry and wet, the growth rates inside and outside the tubers become uneven, and cracking of the skin often occurs. In short, sweet potatoes fear both waterlogging and drought. As people say: “Dry soil grows woody roots, wet soil grows fibrous roots, and neither dry nor wet soil grows tubers.” To obtain a high sweet potato yield, irrigation should be timely and appropriate according to specific conditions, drainage should be thorough and timely, and in dry land, intertillage should be strengthened to preserve soil moisture.
4. Nutrients: Sweet potatoes have a strong ability to absorb fertilizer and tolerate poor soil, but to achieve high yield, sufficient fertilizer must be applied. In addition to nitrogen, phosphorus, and potassium, sulfur, iron, magnesium, calcium, and others also play important roles. Among the three major elements, sweet potatoes require the most potassium, followed by nitrogen, and the least phosphorus. According to analysis, every 1,000 jin of sweet potatoes 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 applying nitrogen and phosphorus fertilizer timely and appropriately has a notable yield-increasing effect.
5. Soil: Deep soil with rich organic matter, loose texture, good aeration, and good drainage, such as sandy loam and sandy soil, is best. When the soil texture is heavy and sticky, the tuber skin color is poor and rough, the tuber shape is irregular, the yield is low, and it stores poorly. However, sandy loam and sandy soil generally have relatively low fertility and poor water retention, so fertility should be gradually improved through measures such as fertilization before high yield can be obtained. Sweet potatoes are relatively tolerant of acidity and alkalinity, adapting to a pH range of about 4.5-8.5, but 5.2-6.7 is preferable. When the soil salt content exceeds 0.2%, sweet potatoes should not be planted.
Sweet potatoes are fairly common in our lives, and there are many ways to eat them. Usually they can be boiled or roasted, so sweet potato cultivation is also very common in the market, but to increase the yield of sweet potatoes, you must first understand the growing conditions for sweet potatoes.