1. Fertilizer requirement characteristics and fertilizer requirement of watermelon

Each production of 1000 kg watermelon fruit requires 3. 1 kg pure nitrogen, 0.2 kg phosphorus pentoxide 1.2 kg potassium oxide. Watermelon needs more nitrogen and potassium fertilizer and less phosphorus during the whole growth period. According to the annual production level of watermelon in greenhouse and the soil fertility situation in our region, when the planned watermelon yield is 3800-4000 kg/mu, it is appropriate to apply 60-65 kg of urea, ordinary superphosphate 100 kg, 50% potassium sulfate 34-36 kg, or compound fertilizer with equivalent nutrient content, zinc fertilizer 1 kg and boron fertilizer/kloc-.

2. Fertilization method

(1) base fertilizer: all organic fertilizers, phosphate fertilizers, boron fertilizers, zinc fertilizers, 40% urea and 50% potassium sulfate are used as base fertilizers.

(2) Topdressing: topdressing 20% urea at the vine elongation stage of watermelon. After fruit setting, topdressing 40% urea and 50% potassium sulfate when watermelon eggs are large.

(3) Spraying fertilizer on leaves: Combining with the pest control during the expansion period of melon, spraying 0.2% boron fertilizer or 0.3-0.5% potassium dihydrogen phosphate on leaves can not only prevent premature aging, enhance the stress resistance of plants, but also improve the yield and quality of watermelon.