Watermelon needs a variety of nutrients to grow, and the fertilizer requirements are different at different growth stages. The following are some fertilizers suitable for watermelon:
- Base fertilizer
- Organic fertilizer: such as decomposed farmyard manure (pig manure, cow manure, chicken manure, etc.), compost, green manure, etc., which are rich in various nutrients, can improve soil structure, improve soil fertility and water and fertilizer retention capacity, and provide long-term nutrient support for watermelon growth. The general application amount per mu is 2000-3000 kg.
- Cake fertilizer: Common ones include bean cake, cottonseed cake, rapeseed cake, etc., which have a high nitrogen content and a certain amount of phosphorus, potassium and other trace elements. The fertilizer effect is long-lasting and stable. The application amount per mu is about 100-150 kg.
- Chemical fertilizer: Use potassium sulfate compound fertilizer, the ratio of nitrogen, phosphorus and potassium is generally 15:15:15 or 16:16:16. Compound fertilizer can provide a variety of main nutrients required for watermelon growth and meet the nutrient requirements of watermelon in the early stage of growth. Generally, the application amount per mu is 30-50 kg.
- Topdressing
- Seedling fertilizer: Watermelon seedlings have relatively few nutrient requirements, but in order to promote the healthy growth of seedlings, a thin nitrogen fertilizer, such as urea, can be applied once when the seedlings grow 2-3 true leaves, with a dosage of 5-8 kg per mu to promote the growth of seedling roots and leaves.
- Vine fertilizer: The growth rate of watermelon vines is accelerated during the vine extension period, and the fertilizer requirement increases. During this period, nitrogen fertilizer should be used as the main fertilizer, and phosphorus and potassium fertilizers should be applied in combination. High-nitrogen compound fertilizers, such as compound fertilizers with a nitrogen, phosphorus and potassium ratio of 20:10:10, can be used, with an application amount of 15-20 kg per mu to promote the rapid growth of vines and the expansion of leaf area.
- Fertilizer for fruit swelling: The fruit swelling period of watermelon is the period when the fertilizer demand is the highest. At this time, potassium fertilizer should be applied heavily, along with nitrogen fertilizer and phosphorus fertilizer. Potassium sulfate compound fertilizer (15:15:15) of 20-30 kg and potassium sulfate of 10-15 kg can be applied per mu to promote fruit swelling and improve the quality and sweetness of watermelon. During the fruit swelling period, foliar topdressing can also be carried out according to the growth of watermelon, such as spraying 0.2%-0.3% potassium dihydrogen phosphate solution once every 7-10 days, and spraying 2-3 times continuously, which can effectively improve the sugar content and fruit quality of watermelon.
In the actual fertilization process, the amount and method of fertilizer should be flexibly adjusted according to factors such as soil fertility, watermelon variety, and planting density, so as to achieve scientific fertilization and achieve high-quality and high-yield watermelon.
