If watermelons are sweet, they must be fertilized with potash.

According to the investigation, the problem of the imbalance of nitrogen, phosphorus and potassium in melon soil is more prominent at present. Watermelon is a crop that needs potassium. The application of potassium fertilizer can increase the sugar content of fruit. When potassium fertilizer is applied to watermelon, it is generally possible to apply potassium sulfate 12 kg per mu, that is, 3 kg of base fertilizer per mu, 6 kg of topdressing at seedling stage, 7 kg of topdressing at seedling stage, 7 kg of potassium chloride at fruiting stage, and 10 kg of potassium chloride per mu, that is, 2 kg per mu of base fertilizer, 4 kg at seedling stage and 4 kg at melon stage. Potash fertilizer is rich in chicken, sheep, rabbit manure, aquatic plants and plant ash, and the sugar content of watermelon can reach 9.5 degrees after application. In addition, when melon farmers apply chemical fertilizers to watermelons, the weight ratio of nitrogen, phosphorus and potassium should be 1: 1, 2.5: 1, that is, the application of nitrogen, phosphorus and potassium per mu is 3 kg of nitrogen, 7.5 kg of phosphorus and 3 kg of potassium. Melon farmers can also apply fertilizer flexibly according to the soil fertility, but the amount of nitrogen fertilizer should not be too large. The results show that the imbalance of nitrogen, phosphorus and potassium in melon soil is more prominent at present. Watermelon is a crop that needs potassium. The application of potassium fertilizer can increase the sugar content of fruit. When potassium fertilizer is applied to watermelon, it is generally possible to apply potassium sulfate 12 kg per mu, that is, 3 kg of base fertilizer per mu, 6 kg of topdressing at seedling stage, 7 kg of topdressing at seedling stage, 7 kg of potassium chloride at fruiting stage, and 10 kg of potassium chloride per mu, that is, 2 kg per mu of base fertilizer, 4 kg at seedling stage and 4 kg at melon stage. Potash fertilizer is rich in chicken, sheep, rabbit manure, aquatic plants and plant ash, and the sugar content of watermelon can reach 9.5 degrees after application. In addition, when melon farmers apply chemical fertilizers to watermelons, the weight ratio of nitrogen, phosphorus and potassium should be 1: 1, 2.5: 1, that is, the application of nitrogen, phosphorus and potassium per mu is 3 kg of nitrogen, 7.5 kg of phosphorus and 3 kg of potassium. Melon farmers can also apply fertilizer flexibly according to the soil fertility, but the amount of nitrogen fertilizer should not be too large.