When are sweet potatoes harvested, and how should potassium fertilizer be applied?

The sweet potato is a very high-yielding and easy-to-grow crop with strong adaptability, and it is widely planted in both the north and south of the country. So when are sweet potatoes generally harvested? How is potassium fertilizer used?

1. When are sweet potatoes generally harvested?

Sweet potatoes are divided into spring sweet potatoes and summer sweet potatoes, usually called early sweet potatoes and late sweet potatoes. Spring sweet potatoes are generally planted around April 15, until around the “May Day” holiday. Summer sweet potatoes are generally planted in mid-June. The seedlings of summer sweet potatoes are cut directly from the seedlings of spring sweet potatoes for cuttings. The growth period of spring sweet potatoes can reach about 160~200 days. Within the appropriate harvest period, the later the harvest, the higher the yield. The longer the sweet potato grows, the more starch it contains, which is most welcomed by processing enterprises that need to make starch, vermicelli, and so on. The growth period of summer sweet potatoes is relatively short, generally about 110 days to 120 days. From planting the seedlings to the vine-spreading stage, spring sweet potatoes are in a period of rapid root growth. At this time, root formation is the main process: the underground root system grows quickly, while the aboveground part grows slowly. It generally takes about two months before they enter the stage of faster aboveground growth. Late sweet potatoes take about one and a half months.

2. How is potassium fertilizer used when planting sweet potatoes?

1. In the application of base fertilizer, we must do a good job with the use of potassium fertilizer in the bottom fertilizer and base fertilizer. For example, add plant ash to organic fertilizer, operating at a rate of 100~150 kg per mu. Of course, farm organic fertilizer with a relatively high potassium content can also be used, at 4000~5000 kg per mu. If plant ash is used, be sure not to use it together with acidic fertilizers, so as to avoid acid-base neutralization, which would cause the fertilizer effect to be lost. In addition, sweet potatoes are chlorine-sensitive crops, so it is best not to use potassium chloride, but to use potassium sulfate.

2. When cutting sweet potato vines, an appropriate amount of potassium sulfate can be mixed with water to make a potassium solution, and the sweet potato vines can be soaked in it for about one hour. This can improve the survival rate during cutting. The ratio of the potassium solution is 1 kg of potassium sulfate to 50 kg of water.

3. After the sweet potato seedlings have been planted for 30~40 days, the first topdressing can begin. Apply it in holes at a standard of 10 kg of potassium sulfate per mu. When the sweet potato vines grow to 100 cm, plant ash can be appropriately used for topdressing, because plant ash is also a farmyard manure with very high potassium content. The standard is 40~60 kg per mu. Before the sweet potatoes are about to mature, that is, about 50 days before harvest, foliar fertilizer can be used, spraying the sweet potato leaves with a 1% potassium sulfate solution or a 0.2% potassium dihydrogen phosphate solution, generally spraying 2~3 times in a row, with an interval of about one week each time. This can significantly increase the yield of sweet potatoes.