How to top up during the expansion period of sweet potatoes?

How to top up during the expansion period of sweet potatoes? What kind of method is effective? I also hope that netizens can help introduce that the root expansion period of sweet potato tuber is generally from late July to early September every year, which is the key period for yield formation and the period when the most fertilizer is needed. The farming network has sorted out several topdressing methods for sweet potato expansion period, which are listed below for netizens' reference. Method 1. Hole topdressing method: 20 cm away from the main root of sweet potato, drill a hole about 30 cm deep, apply appropriate amount of ternary compound fertilizer, and seal it with wet soil. If you drill a hole on each side of the ridge to topdressing, the effect is better. By using this method, the yield can be increased by about 20% per mu. Method 2. Crack topdressing method: when sweet potato expands and cracks appear on the ground, 0.5 kg of potassium dihydrogen phosphate per mu is mixed with 400 kg of water, or 2.5 kg of urea and 10 kg of calcium superphosphate are mixed with 500 kg of water, and the fertilizer solution is poured into the crack, 0.7 kg per plant. After 15 days, 100 kg of plant ash per mu plus 500 kg of water, soaked for 4 hours, the supernatant was poured into the cracks, and the cracks were sealed with soil after irrigation. Method 3. Foliar topdressing method: 0.3% potassium dihydrogen phosphate solution was sprayed on the leaf, once every 7 days. Using this method, the yield can be increased by 18% to 20% per mu. Click to get more sweet potato planting techniques click to get more vegetable planting techniques