Vegetables cultivated in greenhouses, due to the artificially created conditions for temperature increase and heat preservation, avoid the disastrous climate, accelerate the growth process, and make the vegetables mature and high yield. However, due to the accelerated production cycle of vegetables, the amount of fertilizer required is larger than that of open-air vegetables, which is 50% higher than the general amount. It is precisely because of the increase in the amount of input that, if improperly controlled, it will bring about some negative effects, especially in winter and early spring, so pay attention to reasonable fertilization.
Adjust the ratio of base fertilizer and top dressing. In order to prevent excessive fertilizer application at one time, the principle of applying sufficient base fertilizer and applying less topdressing should be mastered. Generally, the proportion of basal fertilizer should account for 60% of the total fertilizer input. Among them, phosphate fertilizer can be increased to 70% due to slow decomposition. High-quality farmhouse compost and barnyard manure must be fully decomposed, and the usage amount per mu is about 5,000 kg. High-quality organic compound fertilizer is generally 75 kg per mu, and should not exceed 100 kg. The remaining top dressing is flexibly controlled according to the growth of vegetables and the regular period of fertilizer requirement.
Appropriate increase in organic fertilizer. The organic fertilizer has a comprehensive and balanced nutrition, which can not only improve the soil, increase the fertilizer and water retention capacity, but also adjust and balance the pH of the soil and prevent the soil from fertilizer damage due to centralized fertilizer supply. In addition to the application of composted fertilizers, the application of bio-organic fertilizers or bacterial fertilizers should also be vigorously promoted.
Implement formula fertilization. According to the fertilizer requirements of different vegetables and the status of soil fertilizer, determine the appropriate amount of nitrogen, phosphorus, potassium and trace elements and the corresponding fertilization technology. According to the research results of relevant departments, the maximum demand periods for nitrogen, phosphorus, and potassium of greenhouse vegetables are: 75 to 140 days after planting for cucumber, 30 to 52 days for tomato, and 30 to 60 days for sweet pepper. . The best fertilizer application ratio (nitrogen, phosphorus, potassium) is 1:0.67:1.83 for cucumber, 1:0.38:1.75 for tomato, and 1:0.38:1 for sweet pepper. Vegetables require very little trace elements, but they are indispensable. Use micro-fertilizer foliar sprays, and the dosage standards should be good. Be careful not to spray fertilizer on leafy vegetables to avoid increasing nitrate content.
Shallow top dressing is prohibited. Because of the high degree of airtightness of greenhouse vegetables, shallow fertilization or spreading of fertilizers can easily volatilize fertilizer, which reduces fertilizer efficiency and easily produces ammonia hazards. Therefore, the top dressing must be applied in a hole or in strips, with a depth of 5-6 cm, and a distance of 8-10 cm from the roots of the vegetables.
Apply nitrogen fertilizer at an appropriate temperature. Nitrogen fertilizers, especially urea and ammonium bicarbonate, are only easily absorbed by vegetables when they are converted into nitrate nitrogen, and the speed of conversion depends on the temperature in the shed. When the temperature in the shed is lower than 15°C, nitrifying bacteria and activities will be inhibited. Therefore, topdressing nitrogen fertilizer should be carried out around noon on a sunny day. Too early or late will reduce the effect of topdressing due to low temperature. For nitrogen-deficient vegetables or leafy vegetables, spraying 0.5% to 1.0% concentration of urea solution will be better.
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