Time and method of fertilization for watermelon

Fertilization at seedling stage: sufficient base fertilizer should be applied before watermelon planting, but no fertilizer should be applied at seedling stage, urea should be applied when plants grow 3-4 true leaves, and 10-20cm should be paid attention to to prevent root burning. Extension period: when the melon vine grows to 40-50cm, urea, high nitrogen compound fertilizer or potassium sulfate can be applied per mu. Expansion period: a large amount of fertilizer is needed, mainly applying phosphorus and potassium fertilizer. Late growth period: if premature senility and yellowing of melon vine occur, potassium dihydrogen phosphate can be sprayed.

First, apply base fertilizer

1. Watermelons should apply sufficient base fertilizer before planting, mainly organic fertilizer, together with a small amount of chemical fertilizer, which accounts for about 70% of the total fertilizer application.

2. If watermelons are planted in soil with medium or above fertility, about 4000 kg of organic fertilizer can be applied per mu, with about 15 kg of diammonium phosphate, 25 kg of potassium sulfate and 15 kg of urea. Then ploughing and mixing fertilizer and soil evenly.

2. Topdressing fertilizer

Watermelon can be fertilized according to the principle of light application in seedling stage, skillful application in vine stage and re-application in expansion stage.

1. Fertilization at seedling stage

In the seedling stage, if the base fertilizer is sufficient, basically no topdressing is needed, but fertilization can be carried out according to plant growth and soil fertility. Generally, topdressing can be carried out when the plant grows 3-4 true leaves, and urea can be applied to about 10 kg per mu. Attention, it is not appropriate to be too close to the root, about 10-20cm away from fertilization to prevent root burning.

2. Extension period

(1) the amount of fertilizer can be increased appropriately according to the growth of watermelon. When the vine grows to 40-50 cm, in order to accelerate the growth of the vine, about 15-20 kg of urea, 20-25 kg of high-nitrogen compound fertilizer or 10-15 kg of potassium sulfate can be applied per mu, which can be combined with watering.

(2) if the plant is applied with sufficient base fertilizer and seedling fertilizer, less nitrogen fertilizer should be applied. In order to avoid excessive growth of watermelon and affect fruit setting, early fertilization should be applied in the middle and later stage of vine extension.

3. Expansion period

(1) the amount of fertilizer needed in the watermelon expansion period is relatively large, so fertilizer must be applied in time, mainly phosphorus and potassium fertilizer, together with a small amount of nitrogen fertilizer, which is helpful to promote fruit expansion and thus increase the yield of watermelon. The amount of fertilizer applied at this stage accounts for 50% of the amount of topdressing, which can be divided into two times.

(2) wait until about 4-5 days after the flowering of the plant, when the fruit grows to the size of eggs, about 5 kg of urea, 25 kg of potassium sulfate and 15 kg of diammonium phosphate can be applied per mu, and about half a month after flowering, when the fruit grows to the size of the bowl mouth, using the method of hole application, about 10-15 kg of potassium sulfate and 15-20 kg of diammonium phosphate can be applied per mu, and the final watering can be done.

4. Late growth stage

In the later stage of watermelon growth, if premature senescence occurs and melon vines turn yellow, in order to replenish plant nutrients in time, you can choose 0.2-0.3% potassium dihydrogen phosphate or 0.3-0.4% Feilibao foliar spraying.