August and September are the expansion of sweet potato roots. When cracks appear in the local topsoil, irrigation of cracked fertilizers can promote the expansion of sweet potato roots. The following formulas can be used when formulating the joint-filling fertilizer: 1. Use 750-1000 kg of human excrement per acre, mix 500 kg of fresh water and inject at about 5 pm; 2. Use 500 g of potassium dihydrogen phosphate per acre. After dissolving in warm water, add 500 kg of fresh water and then pour it into the cracks. 3. Use 2.5 kg of urea and 10 kg of superphosphate per acre. Dissolve 500 kg of water with a small amount of water. After the mu is dissolved with 100 kg of ash, it is soaked for 5 hours. The impurities are filtered out and 500 kg of water is poured into the roots. It is worth noting that no matter which of the above methods is used to irrigate the roots, the action must be slow. Immediately after the fertilization solution is applied, the cracks shall be sealed with fine topsoil to reduce the exertion of the fertilizer effect and the evaporation of water, and play a role in drought resistance. . In the late growth stage of sweet potato, the concentration of potassium dihydrogen phosphate solution with a concentration of 0.3% per acre can be increased from 75 to 100 kg. China Agricultural Network Editor
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