Watermelon is a heavy-feeding crop, requiring different types and quantities of fertilizers at different growth stages. Farmers should pay attention to the combination of organic and chemical fertilizers, while controlling the application of nitrogen, phosphorus, and potassium. So, what fertilizer should be used to grow large and sweet watermelons? Let's find out below.
What Fertilizer to Use for Growing Large and Sweet Watermelons?
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Apply Sufficient Base Fertilizer: Adequate base fertilizer is the premise for high watermelon yields. In the watermelon's lifecycle, base fertilizer accounts for sixty percent of the total fertilization. Insufficient base fertilizer may result in slow seedling growth, inadequate nutrient accumulation, fewer flowers and fruits, affecting the yield and quality of watermelons. When applying base fertilizer, use organic fertilizer and phosphate fertilizer with long-lasting effectiveness and full nutrients. Control the application of quick-acting nitrogen fertilizer to avoid excessive nitrogen during the seedling stage. For each acre, mix 3 tons of decomposed farmyard manure, 30 kilograms of urea, 15 kilograms of calcium superphosphate, 45 kilograms of potassium sulfate, 5 kilograms of magnesium sulfate, and 0.5 kilograms of borax into the soil.
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Apply Seedling Fertilizer Lightly: Generally, if there is sufficient base fertilizer, seedling fertilizer may not be applied. However, for plots with insufficient base fertilizer or unclear effectiveness of base fertilizer, timely application of seedling fertilizer is conducive to seedling growth and root development. When the seedlings have 2-3 true leaves, apply the first top dressing mainly with quick-acting nitrogen fertilizer. Apply 2-3 kilograms of urea per acre in the form of hole application about 10 centimeters away from the seedlings.
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Apply Vine Extension Fertilizer Skillfully: After watermelon vines extend, there is a strong demand for nitrogen, phosphorus, and potassium for vine growth and flower formation. Apply the second top dressing, prioritizing fertilizers with full nutrients, large quantities, and long-lasting effectiveness, such as cake fertilizer and compound fertilizer. Apply 15 kilograms of compound fertilizer per acre, dig holes about 10 centimeters away from the roots, mix the soil and fertilizer evenly with a shovel, compact the trench, level the ground, and then water appropriately to promote absorption.
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Apply Melon Expansion Fertilizer Heavily: The melon expansion period is a critical period for top dressing. Insufficient nutrients or untimely supply can lead to small-sized and poor-tasting watermelons. Generally, the third top dressing is performed in two steps. When the young fruits are the size of an egg, apply the first top dressing by digging trenches 30-40 centimeters away from one side of the plants. Apply 15-20 kilograms of calcium superphosphate and 6-7 kilograms of potassium sulfate per acre. If readily available, wood ash can be used instead of potassium sulfate because it is rich in potassium and phosphorus, thus being nutritious and environmentally friendly. When the fruits are the size of a bowl, apply the second melon expansion fertilizer in a timely manner. Spray potassium dihydrogen phosphate foliar fertilizer every 7 days for 2-3 consecutive times.
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Apply Recovery Fertilizer After Harvest: Immediately apply the fourth top dressing after the first harvest. Apply high-efficiency compound fertilizer containing phosphorus and potassium, such as potassium dihydrogen phosphate foliar fertilizer, at a rate of 10-15 kilograms per acre. This helps to quickly replenish phosphorus and potassium elements to promote plant growth and flower bud differentiation, increase the number of flower buds, and prevent early senescence of vines and leaves.
Above are the details of what fertilizer to use for growing large and sweet watermelons. In addition to the essential nutrients nitrogen, phosphorus, and potassium, normal watermelon growth also has special requirements for trace elements such as calcium and magnesium.
