Watermelon fertility requirements

Watermelon has wide adaptability and can be cultivated in sandy soil, loamy soil and clay soil. However, the root system of watermelon has obvious aerobic properties and is suitable for planting on sandy soils with deep soil layers, good drainage and rich organic matter.

In the absorption of the three elements of nitrogen, phosphorus and potassium in the whole growth period of watermelon, potassium is the most, followed by nitrogen, and phosphorus is less.

The absorption amount and absorption ratio of nitrogen, phosphorus and potassium in different growth stages of watermelon are different. Absorption during the germination period is very small, accounting for only 0.01% of the total growth period. The absorption during the seedling period is also less, accounting for only 0.54% of the entire growth period. The absorption during the vine period increases, accounting for 14.67% of the entire growth period. , The above three periods are dominated by vegetative growth, and the proportion of nitrogen fertilizer absorption is relatively large. The amount of fertilizer absorption during the fruiting period is large, accounting for about 84.78% of the entire growth period. Among them, the amount of potassium absorption is large, especially in the fruit expansion period, which is closely related to the improvement of watermelon quality. This shows the importance of watermelon nutrition in the later period. .

How to fertilize watermelon

Base fertilizer: MAINPAR 16-16-16 nitrosulfur-based compound fertilizer and Haofangzi 15-15-15 sulfur-based compound fertilizer can be selected from 50-60kg.

Topdressing in the vine-stretching period: In the vine-stretching period, the demand for fertilizer and water gradually increases. At this time, the top dressing should aim at promoting the growth of vine leaves and expanding the leaf area, but to prevent excessive growth.

Topdressing in the early stage of fruit swelling: The fruit begins to swell rapidly, and the fertilizer requirement of the plant gradually reaches the peak of the whole growth period. At this time, swelling melon fertilizer should be reapplied to promote fruit swelling and sugar accumulation, and prevent premature aging. It can be topdressed with 20-25kg of MAINPAR 16-6-26/13-8-27 compound fertilizer.

Remarks: The application methods of the above fertilizers vary from place to place.

Eight prohibitions on fertilizing watermelon

Nitrogen fertilizer cannot be applied alone. Watermelon fertilization requires the combined application of nitrogen, phosphorus, and potassium fertilizers.

■ Do not apply chlorine-containing fertilizers. Watermelon fertilizers should be urea, ammonium sulfate, potassium sulfate, etc., and ammonium chloride, potassium chloride and other chlorinated fertilizers should not be used.

■ Do not apply heavy fertilizer during drought. The weather is dry and the soil water content is low. High-concentration liquid fertilizer cannot be used. Water or irrigation must be done first to moisten the soil before applying fertilizer.

■ You should not fertilize on cloudy or rainy days. In cloudy and rainy days, the air temperature is high, the soil moisture content is high, and the ability to absorb fertilizer and maintain fertilizer is poor. Applying fertilizer at this time, the fertilizer is not only easy to lose, but also causes the vine leaves to grow, and the tender leaves of the vine are brittle and easy to induce pests and diseases.

■ It is not suitable to apply fertilizer near the roots. With the continuous elongation of the watermelon vines, the roots of the watermelon gradually expand accordingly. Fertilization under the roots will not fully absorb and utilize the fertilizer.

■ Do not fertilize the topsoil layer. In hot and dry weather, if fertilizer is applied to the topsoil layer, not only the nutrients are easily volatilized, but also the roots are burnt. Therefore, the fertilization should be applied at a depth of 20-40 cm from the roots, and then covered with soil.

■ Do not apply ammonium bicarbonate when the surface soil is dry. When applying ammonium bicarbonate, whether it is used as a base fertilizer or top dressing, it should be covered with soil immediately after deep application when the soil is moist. In case of dry weather, water with water or water after application.

■ It is not suitable to irrigate immediately after applying urea. The nitrogen contained in urea exists in the state of amide. The amide is absorbed and utilized by the watermelon roots after the nitrogen is converted to ammonium carbonate or ammonium bicarbonate. It usually takes 3-5 days to be transformed. Whether urea is used as a base fertilizer or top dressing, it should be used in the watermelon roots. Water can only be irrigated after the transformation is completed.