Topdressing of watermelon cultivated in summer and autumn

The growth period of watermelon cultivated in summer and autumn is short, fertilizer requirements are concentrated, base topdressing should be based on quick-acting fertilizer, nitrogen, phosphorus and potassium fertilizer should be properly matched, sufficient supply. Base fertilizer is applied during soil preparation, 75 to 100 kg of rotten cake fertilizer, 30 to 40 kg of calcium phosphate per mu, or 40 to 50 kg of nitrogen, phosphorus and potassium three-element compound fertilizer. Plant extension, combined with ploughing per mu of diammonium phosphate 15 to 20 kg, potassium sulfate 5 to 7.5 kg, or ternary compound fertilizer 20 to 25 kg, urea 10 kg. In addition, 0.2% to 0.3% potassium dihydrogen phosphate can be sprayed in combination with pest control, which can improve the quality.