Why Mid-Season Sweet Potato Management Requires Heavy Potassium Fertilizer Application

This year, the sweet potato cutting period encountered drought, resulting in a low survival rate, so the planting density decreased somewhat, which will affect this year's sweet potato yield. Throughout its life, sweet potato has the greatest demand for potassium among all nutrients, especially when it enters the tuber bulking stage, when it needs a large amount of potassium. If potassium fertilizer is applied at this time, it can meet the sweet potato's demand for potassium, and if accompanied by appropriate amounts of phosphate fertilizer and nitrogen fertilizer, it can greatly promote tuber bulking, increase the rate of large tubers, and significantly increase the yield per unit area.

1. Apply plant ash. Plant ash contains a relatively large amount of potassium and also contains various nutrient elements such as phosphorus and calcium. When applied properly, it can produce a significant yield increase. The specific method is as follows: for sweet potatoes whose ridges have already closed, choose a windless evening and broadcast it, using 4 baskets of plant ash per mu, and spread it evenly on the leaf surface; for potato fields planted later, with vines within 50 cm and ridges not yet closed, use 4 baskets of plant ash per mu mixed with 1 kg of urea, apply it at the base of the plants, one handful of ash fertilizer per plant.

2. Apply potassium dihydrogen phosphate as a topdressing. For plots that have not yet formed tubers, use 40 kg of a 0.3 percent potassium dihydrogen phosphate solution per mu, add 0.5-1 kg of urea, and evenly spray it on the leaf surface after 4 p.m. on a sunny day or on a cloudy day; for plots that have already formed tubers, use 500-750 g of potassium dihydrogen phosphate plus 1.5-2 kg of urea per mu, mix with 200-250 kg of water, stir evenly, and after fully dissolving, pour it along the roots.