Matters needing attention in fertilization of watermelons in greenhouse with large yield and high quality

Fertilization of watermelon in greenhouse

1 characteristics of fertilizer requirement:

Watermelon grows fast and needs a large amount of fertilizer, especially in greenhouse production, the yield per mu can reach more than 3500kg, and the amount of fertilizer required increases obviously. The practice shows that the yield of 3500kg watermelon per mu needs to absorb nitrogen 10.7kg, phosphorus 3.8kg and potassium 11.5kg, with a ratio of 2.8: 1 to 3.1. On the basis of ensuring the supply of nitrogen fertilizer, watermelon in greenhouse should apply more organic fertilizer, phosphorus and potassium fertilizer to avoid excessive growth or poor quality of watermelon caused by partial application of nitrogen fertilizer. Because the growth amount and growth rate of watermelon are different in different growth stages, the nutritional requirements are also different. The overall characteristics of fertilizer demand are as follows: in the seedling stage, the absorption of nutrients is less, and the absorption of nitrogen, phosphorus and potassium accounts for only 0.55% of the total; in the trailing stage, the growth rate is accelerated, and the growth is increased, accounting for about 14.6% of the total; in the melon stage, the growth is the largest, accounting for about 84.85%. During this period, the absorption of potassium increased and the absorption of nitrogen decreased.

2 key points of fertilization technology:

2.1 fertilization in seedling bed: the nutrient soil used for watermelon seedling cultivation is required to be rich in organic matter, loose, strong in water and fertility conservation. To prepare nutritious soil, use 1 part of rotten toilet manure, 1 part of unplanted pastoral topsoil and 1 part of fine crushed slag, break and mix well, sieve, then add urea 1kg, diammonium phosphate and potassium sulfate each 0.5kg per square meter, add 25g carbendazim and phorate 0.5kg, mix evenly, pile up for 7 days and 10 days, then put into a nutrition bowl and seed to be sown.

2.2 soil preparation and fertilization: the re-application of base fertilizer is the basis to ensure the robust growth and high yield of watermelon stems. After the previous crop harvest, combined with deep ploughing and soil preparation, applying rotten organic fertilizer 4000kg per mu, planting the ditch deeply according to the prescribed row spacing 30cm, applying thick 10cm organic fertilizer at the bottom of the ditch, applying compound fertilizer 30kg or urea 10kg, diammonium phosphate and potassium sulfate each 15kg, and then applying a layer of thick 10cm organic fertilizer, the top layer was applied with 20 kg compound fertilizer or diammonium phosphate, potassium sulfate and urea 10kg, the chemical fertilizer, organic fertilizer and soil in the ditch were mixed evenly, leveled and ridged, and watered in time. And cover plastic film and greenhouse film.

2.3 topdressing after planting

2.3.1 stretch vine fertilizer: when watermelon enters the extension period, the demand for fertilizer and water increases. Topdressing at this time should aim at promoting vine leaf growth and expanding leaf area, but should prevent overgrowth. Topdressing is mainly rotten organic fertilizer, combined with appropriate amount of chemical fertilizer, the amount of fertilizer is organic fertilizer 750kg per mu, compound fertilizer 15kg, rotten cake fertilizer 50~75kg, calcium superphosphate 10kg, potassium sulfate 10kg 12kg, urea 10kg, mixed and applied. After furrow application, 20cm deep fertilizer ditch was opened at one side of plastic film from 20cm of watermelon root. After fertilizing and sealing ditch, the soil was watered in time to keep the soil dry and wet.

2.3.2 expanded melon fertilizer: when the normal watermelon grows to the size of an egg, it begins to expand rapidly, and the amount of fertilizer required gradually reaches the peak of the whole growth period. At this time, we should re-apply expanded melon fertilizer to promote melon expansion and prevent premature senility. Topdressing is mainly phosphorus and potassium fertilizer, with little or no application of nitrogen fertilizer to avoid reducing the quality of watermelon due to excessive nitrogen fertilizer. 15kg diammonium phosphate, potassium sulfate 15kg, urea 10kg or compound fertilizer were applied per mu. It was applied in the hole next to the ridge and 30cm of the melon root, or between the two plants near the ditch. After fertilization, water was poured in time to promote the absorption of nutrients and accelerate the expansion of watermelon.

2.3.3 Rehabilitation fertilizer: immediately after the first stubble melon harvest, quick-acting chemical fertilizer was applied immediately, generally applying urea 15-20kg, potassium sulfate 15kg, diammonium phosphate 10kg per mu, combined with topdressing, watering once. By strengthening management and replenishing nutrients and water in the soil, watermelon can maintain strong growth and prevent premature senescence of vine leaves.

2.4 skillfully applying foliar fertilizer:

Foliar fertilizer spraying is a necessary means to make up for the deficiency of watermelon root absorption, supplement and balance nutrients to watermelon, which has the characteristics of low cost, uniform fertilization, fast fertilizer efficiency, high utilization rate and so on. Generally, starting from the expansion period of white stubble melons, 0.3% 0.5% potassium dihydrogen phosphate solution is sprayed every 7~l0d (days); it can enhance the stress resistance of watermelons, increase the flowering rate and sugar content of watermelons, improve quality and increase yield, and play a more significant role.