How to correctly fertilize watermelon from base fertilizer to topdressing?

Because watermelon has a long growth period, it needs a large amount of fertilizer. Today, we will talk about the fertilization technology of watermelon in detail.

First, the law of watermelon fertilizer demand

During the whole growth period of watermelon, the amount of potassium absorbed was the most, followed by nitrogen and phosphorus. Watermelon generally needs fertilizer because it absorbs relatively few nutrients at seedling stage, and the absorption of nitrogen, phosphorus and potassium accounts for only 0.6% of the total absorption. The growth rate of watermelon began to accelerate during the elongation period, and the growth amount will also increase, accounting for about 14.6% of the total absorption. Watermelon has the largest growth at fruiting stage, and its absorption accounts for about 84.8%.

According to the test report, per 65,438+0,000 kg of watermelon fruit, pure nitrogen is 2.5-3.2 kg, phosphorus pentoxide is 0.8-65,438+0.2 kg, potassium oxide is 2.9-3.6 kg, and the ratio of nitrogen, phosphorus and potassium is about 3: 65,438+0: 4.

The absorption rate of three elements by watermelon plants in different periods is also different. From seedling to flowering stage, plants absorb nitrogen the most, followed by potassium. In the fruit-bearing stage of watermelon, plants absorb most potassium, followed by nitrogen. Therefore, nitrogen fertilizer should be the main fertilizer before flowering and fruiting, and the application of phosphorus and potassium fertilizer must be paid attention to in the fruiting period, which can increase the yield and improve the quality. In addition, watermelon is sensitive to trace elements such as boron, zinc and molybdenum, and also has a certain demand for calcium, iron and copper.

Second, the correct fertilization management of watermelon

1, watermelon base fertilizer

It is suggested that 4000 ~ 5000 kg of high-quality organic fertilizer, urea 15 ~ 20 kg, calcium superphosphate 25 ~ 30 ㎏, potassium sulfate/kloc-0 ~15 kg should be applied per mu, or 50 ~ 60 kg of watermelon special fertilizer should be applied in combination with deep tillage. At the same time, it should be noted that the specific amount of fertilization is determined according to the local soil fertility and yield level, and the amount of fertilization will increase with the increase of yield in a certain range. ?

2, watermelon topdressing

◆ Stretch vine fertilizer

When watermelon enters the vine-stretching stage, the demand for fertilizer and water is gradually increasing. At this time, topdressing should aim at promoting the growth and expanding the leaf area of lianas, and preventing overgrowth at this stage. When topdressing, most of them mainly use decomposed organic fertilizer, and then add appropriate amount of chemical fertilizer. The application amount of organic fertilizer per mu is 750 kg. Then what? Special fertilizer for watermelon 15 kg, or 50-75 kg of decomposed cake fertilizer can be applied, and then calcium superphosphate 10 kg, potassium sulfate 10/2 kg, and urea10 kg can be applied after mixing. The method of fertilization is furrowing and strip application, and a furrow with a depth of 20 cm is dug on one side of the plastic film 20 cm away from the root of watermelon plants. After fertilizing and sealing the ditch, water it in time to keep the soil dry and wet.

◆ Expanded melon fertilizer

When the normal young fruit grows to the size of an egg, the fruit begins to expand rapidly, and the fertilizer requirement of the plant will gradually reach the peak of the whole growth period. During this period, it is necessary to reapply expanded melon fertilizer to promote melon body expansion, and at the same time, it is necessary to cover it tightly to prevent premature aging. Pay attention to topdressing mainly with phosphate fertilizer and potash fertilizer, and apply less or no nitrogen fertilizer to avoid the decline of watermelon quality caused by excessive application of nitrogen fertilizer. It is suggested that diammonium phosphate 15㎏, potassium sulfate 15 kg, urea 10 kg, or 20 kg special fertilizer for watermelon. Dig a pit 30㎝ away from the root of melon beside the ridge, or choose to fertilize between two plants near the ditch. Pouring melon fertilizer in time after fertilization can promote nutrient absorption and accelerate fruit expansion.

◆ rejuvenation fertilizer

Immediately after the first watermelon harvest, topdressing 65,438+0 quick-acting chemical fertilizer. In general, it is suggested to topdressing urea 15 ~ 20k g, potassium sulfate 15kg and diammonium phosphate 10kg per mu. At the same time, combined with topdressing, it needs to be watered 65,438+0 times to supplement nutrients and water in the soil to maintain the soil.

◆ Use foliar fertilizer skillfully.

Foliage fertilizer is a necessary means to supplement the insufficient absorption of roots and to supplement and balance the nutrients of plants. It has the characteristics of low use cost, uniform fertilization, fast fertilizer efficiency and high nutrient utilization rate. Generally, it is suggested to spray 0.3% ~ 0.5% potassium dihydrogen phosphate or potassium treasure solution every 7 ~ 10 days, which can enhance the stress resistance of watermelon, improve the flowering and fruiting rate and fruit sugar content, and have obvious effect on watermelon yield increase.

◆ Supplementary application of carbon dioxide gas fertilizer

Supplementing carbon dioxide gas fertilizer in watermelon fruit-bearing period can improve the photosynthetic intensity of leaves and prevent premature senescence of plants, which is an important measure to increase sugar accumulation and increase watermelon yield in greenhouse. Through experiments, acid reaction fertilization is widely used in production at present.

Watermelon fertilization management is one of the important means to improve watermelon yield, and melon farmers can refer to the above methods for rational fertilization when applying fertilizer.