The swelling period of sweet potato roots usually starts in late August, and cracks appear between rows due to the swelling of the roots. At this time, crack fertilizer should be applied to prevent premature aging of the stems and leaves and accelerate the expansion of the tubers. Nitrogen and potassium fertilizers are mainly used for irrigation. Generally, 3%～5% potassium sulfate or 15%～20% plant ash leaching solution is used in late August, and 1% potassium dihydrogen phosphate fertilizer solution can also be used. 150 kg; or topdressing 4 to 5 kg of ammonium sulfate per mu, with 500 kg of water; or 200 to 250 kg of human excrement, 600 to 750 kg of water, and irrigating along the ridge. It can also sprinkle 150-200 kg of ash water per mu. For late-maturing and premature senescence plots, 2% NPK mixture can be irrigated. It is strictly forbidden to turn the vine. Turning the vine will damage the stems and leaves, affect photosynthesis, reduce the accumulation of nutrients, and affect the weight gain of potato chunks. Generally, the yield is reduced by 20% to 25%, and the high is more than 30%. Therefore, sweet potatoes are not suitable for turning vines during the entire growth period. For the sweet potato fields with vigorous growth, it is advisable to control the growth by hitting the vine tips or lifting the vines gently to inhibit the formation of fiber roots, so as to avoid the consumption of nutrients by the fiber roots, improve the photosynthetic capacity of the leaves, and promote the enlargement of potato pieces. Drought prevention and drainage meets dry weather in the later stage of sweet potato growth. Areas with conditions should be watered separately and fertilized with water to promote stem and leaf growth, expand photosynthetic area, and increase photosynthetic products, which is conducive to tuber expansion. However, it is not advisable to water within 20 days before harvest, so as not to reduce the storage tolerance of sweet potato roots. In case of autumn waterlogging, the ditch should be cleared and drained in time to prevent the potato chunks from being waterlogged, forming hard cores and rot, leading to reduced production. Foliar spraying of fertilizer on sweet potatoes will weaken the ability of the roots to absorb fertilizer. Foliar spraying of fertilizer can ensure the nutrients needed for tuber swelling. Generally, 0.5% urea solution should be sprayed on hills and slopes or fields with premature aging; on fields with vigorous leaf and vine growth, 0.2% potassium sulfate or 5% plant ash extract should be sprayed; general fields can be sprayed 0.4%～0.5% urea and potassium dihydrogen phosphate mixture. Spray 75-100 kg of fertilizer solution per mu each time. The spraying time generally starts in mid-August, and spraying once every 7 to 10 days for a total of 2 to 3 sprays. The spraying time should be carried out before the evening on a sunny day. After spraying, it should be sprayed when it rains. Disclaimer: Some articles on this website are transferred from the Internet. If the legal rights of a third party are involved, please inform this website for processing. phone Kerai (Foshan) Technology Co., Ltd. , https://www.cratlock.com