How to apply formula fertilization to hybrid watermelons

Hybrid watermelons require high water and high fertilizer. According to calculations, producing 1000 kg of watermelons requires 5 kg of N, 2 kg of P2O5, and 5 kg of K2O. If hybrid watermelons are planted on medium-fertility soil with a yield of 3000 kg per mu, then 15 kg of N, 6 kg of P2O5, and 15 kg of K2O are required. When fertilizing, achieve:

1. Apply sufficient base fertilizer. Apply 2000 kg of high-quality organic fertilizer and 75-100 kg of cake fertilizer per mu, combined with 50 kg of watermelon special fertilizer or 50 kg of potassium sulfate compound fertilizer. If there is no compound fertilizer, 10 kg of urea, 30 kg of superphosphate, and 10 kg of potassium sulfate can be used. Organic fertilizer and cake fertilizer should be applied in layers or over the entire layer during land preparation, and chemical fertilizers should be mixed evenly with a small amount of organic fertilizer after land preparation and bed formation when watermelons are transplanted, then applied in furrows or holes.

2. Pay attention to fruit-growing fertilizer. Applying fruit-growing fertilizer can promote early fruit set and large fruits, but the amount of supplementary application should be based on soil fertility and seedling conditions. Generally, during the fruit-setting period, when watermelons swell to 0.25 kg, apply 4-5 kg of urea per mu.

3. Do a good job of foliar spraying fertilizer. Watermelon vines are long and leaf area is large, so using foliar spraying fertilizer can improve fertilizer utilization. When watermelons enter the reproductive growth stage, the demand for phosphorus and potassium increases greatly. To prevent premature aging, 50 kg of an aqueous solution of 0.2%-0.5% potassium dihydrogen phosphate plus 0.1% boron and 0.5% ferrous sulfate and other trace elements can be sprayed on the leaves per mu, which not only prevents premature aging and enhances disease resistance, but also improves the quality of watermelons.