Apply potassium fertilizer to sweet potatoes well, and there are methods to double the yield
Sweet potato is a potassium-loving crop. Among the three major fertilizer elements nitrogen, phosphorus, and potassium, potassium is required in the largest amount, followed by nitrogen, and phosphorus the least. Below, the editor will teach you how to apply potassium fertilizer well when planting sweet potatoes!
The best NPK fertilizer ratio for planting sweet potatoes is about 2:1:3. As a tuber crop, sweet potato requires a large amount of potassium during its growth. Relying only on the potassium in the soil is far from enough, and potassium fertilizer must be applied as a topdressing. If sweet potato lacks potassium in the early stage of growth, the internodes and petioles will become shorter and the leaves will become smaller. In the later stage, potassium deficiency causes severe yellowing between the veins of old leaves, which gradually necrose and fall off, greatly affecting the yield. Therefore, scientifically increasing potassium fertilizer application is an important measure for high and stable sweet potato yields.
1. Apply potassium as base fertilizer
Applying sufficient potassium fertilizer as base fertilizer is the foundation for obtaining a high sweet potato yield. Therefore, high-quality organic fertilizer should be the main type used. Because sandy soil has poor water- and fertilizer-holding capacity, semi-decomposed organic fertilizer is suitable as the base fertilizer; while clayey soil is suitable for fully decomposed organic fertilizer. In combination with plowing and ridging, apply 100-150 kg of plant ash per mu, or apply 3500-5000 kg of high-quality farmyard manure rich in potassium, and apply it in layers. When applying plant ash, be careful not to mix it with ammonium nitrogen fertilizer or human manure and urine, so as to avoid nitrogen volatilization loss. In addition, sweet potato is a chlorine-sensitive crop, so potassium chloride must not be applied.
2. Soak sweet potato vines in potassium
Soaking sweet potato vines in potassium can improve survival and promote early growth. The specific method is: add 0.5 kg of potassium sulfate to 25 kg of water and stir thoroughly to prepare a 2% concentration potassium solution, then place the cut sweet potato vine seedlings in the potassium solution to soak, with the top leaves exposed above the water surface. Generally, after soaking for 1 hour, take them out and let them dry slightly before planting.
3. Topdress potassium for sweet potato seedlings
About 40 days after planting, apply 10 kg of potassium sulfate per mu in deep holes opened 7-10 cm from the base of the sweet potato seedlings, then cover with soil after application, to promote the formation and expansion of tuberous roots. When the sweet potato vines grow to about 1 m, on a windless morning with dew, apply about 50 kg of plant ash per mu directly broadcast on the leaf surface, which can prevent excessive vine growth and promote tuber expansion. During the tuber expansion period, if the soil is moist, there is a lot of rain, and the vines and leaves turn yellow, more plant ash can be applied.
4. Spray potassium on the leaves
In the late growth stage of sweet potato, spraying potassium fertilizer solution on the leaves has an obvious yield-increasing effect. Generally, 40-50 days before harvest, use a 1% potassium sulfate solution or a 0.2% potassium dihydrogen phosphate solution or a 5% plant ash extract (soak 5 kg of plant ash in 100 kg of water for 24 hours, then filter out the residue), spray once about every 7 days, for a total of 2-3 sprays, applying 75-100 kg of potassium fertilizer solution per mu each time. Spraying is generally best done in the evening, which helps leaf absorption and enhances fertilizer efficiency.
Sweet potato is a dryland tuber crop with a high fertilizer requirement, and it has no obvious maturity period. At the same time, it avoids waterlogged soil throughout the entire growth period. To achieve a high sweet potato yield, apply a large amount of fertilizer during the cracking stage (tuber expansion stage), and apply fertilizer reasonably in the later stage.