Fertilizer characteristics
Watermelon is an annual vine herb of the genus Cucurbitaceae. The whole life of watermelon can be divided into four stages: germination stage, seedling stage, pumping period and melon period according to different growth and development characteristics. Watermelon has a wide adaptability to soil and is suitable for cultivation in sandy soil and loam with deep soil, good drainage and fertility. However, the sandy land is generally infertile, the fertilizer decomposition and nutrient consumption are relatively fast, and the de-fertilization phenomenon is easy to occur in the late stage of plant growth, which is prone to premature aging. Therefore, rational fertilization is an important measure for high-quality and high-yield watermelon in sandy land.
It is generally considered that nitrogen (N) is 5.08 kg, phosphorus (P2O5) is 1.56 kg, and potassium (K2O) is 6.4 kg per 1000 kg of commercial melon. Nitrogen can promote the normal growth and development of plants, the leaves are green and the vines are strong; phosphorus can promote the transportation of carbohydrates, which is beneficial to the accumulation of sugar in fruits, improve the flavor of fruits, and promote the growth of roots, seed development and fruit ripening; It can promote the growth of stems and strengthen the toughness of stems and enhance the ability to resist cold, disease and wind. Among the three factors of nitrogen, phosphorus and potassium in the whole growth period of watermelon, potassium is the most, followed by nitrogen and phosphorus. The absorption and absorption ratios of nitrogen, phosphorus and potassium in different growth stages of watermelon are different. The amount of absorption in the germination period is very small, accounting for only 0.01% of the total growth period, and the amount of absorption during the seedling stage is also small, accounting for only 0.54% of the total growth period, and the absorption during the extension period increases, accounting for 14.67% of the total growth period. In the above three periods, vegetative growth was the main factor, and the proportion of nitrogen fertilizer absorbed was large. In the result period, the amount of absorbed fertilizer was the highest, accounting for 84.78% of the whole growth period. Among them, the amount of potassium absorbed was the most, especially in the fruit expansion period, and the absorption was the most, which was closely related to the improvement of watermelon quality.
Fertilization technology
The fertilization amount per mu of the whole growth period of watermelon is 3000-3500kg (or commercial organic fertilizer 400-450kg), nitrogen fertilizer (N) 20-23kg, phosphate fertilizer (P2O5) 7-9kg, potassium fertilizer (K2O) 8-11kg can be based on crops. Variety, yield and soil fertility adjust fertilization. Organic fertilizer is used as base fertilizer, nitrogen fertilizer and potassium fertilizer are divided into base fertilizer and topdressing fertilizer, and phosphate fertilizer is used as base fertilizer, and fertilizer and farmyard manure (or commercial organic fertilizer) are mixedly applied.
1. Base fertilizer. Base fertilizer application of farmyard manure 3000-3500kg per mu (or commercial organic fertilizer 400-450kg), urea 6kg, diammonium phosphate 15-20kg, potassium sulfate 5-7kg.
2. Topdressing. Appreciation of the vine season: When entering the vine season, the demand for fertilizer and water is gradually increasing. At this time, the topdressing should aim at promoting the growth of vine leaves and expanding the leaf area, but it is necessary to prevent the occurrence of length. Generally, 10-11 kg of urea and 3-5 kg ​​of potassium sulfate can be applied.
In the early stage of fruit expansion, the topdressing: the fruit began to expand rapidly, and the plant needed fertilizer gradually reached the peak of the whole growth period. At this time, the fertilizer should be reapplied to promote fruit enlargement and accumulation of fruit contents such as sugar, and prevent premature aging. Generally, 13-15 kg of urea and 4-6 kg of potassium sulfate can be applied.
Fruit-expanding mid-term topdressing: 10-11 kg of urea and 3-5 kg ​​of potassium sulfate.
3. Root dressing. In the early and middle stages of watermelon fruit expansion, 0.3%-0.5% potassium dihydrogen phosphate plus 0.1% borax and 0.5% ferrous sulfate aqueous solution can be sprayed on the foliar surface to prevent premature aging and increase disease resistance. Improve the quality of watermelon. Under the conditions of facility cultivation, carbon dioxide gas fertilizer can be added when the watermelon grows vigorously.
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