"Four elements" of fertilizing vegetables in greenhouse


At present, the temperature is gradually rising, greenhouse vegetables are beginning to grow, and management measures such as fertilization and watering are about to start. Due to the large amount of fertilizer applied in greenhouse vegetables, the closure in winter and spring is relatively strict, and the temperature is low and the light is weak. The activity of nitrate reductase in vegetables is low, and nitrate is easily accumulated. Only by scientific and rational fertilization can we reduce the accumulation of nitrate in vegetables. Now briefly introduce the main points of attention in fertilizing vegetables in greenhouses.
1. It is forbidden to apply nitrate nitrogen fertilizer. For example, after applying nitrate nitrogen fertilizer such as ammonium nitrate or potassium nitrate, it is easy to accumulate nitrate in vegetables. In addition, it is not suitable to apply chlorinated fertilizers such as potassium chloride, ammonium chloride, etc., because chloride ions can reduce the starch and sugar content of vegetables, so that the quality of vegetables is reduced, the yield is reduced, and soil compaction is caused. Fertilizers such as magnesium sulfate and ammonium sulfate are applied to the soil, and the sulfate ions decomposed are not easily absorbed by the vegetables and remain in the soil, which is harmful to the growth of vegetables. It is forbidden to apply ammonium bicarbonate, which is easy to cause ammonia damage because it is volatile and a large amount of ammonia gas.
2. Appropriate control of nitrogen fertilizer application The application rate of nitrogen fertilizer should be determined according to the amount of fertilizer required by different vegetables. Generally, 10 to 12 kg of pure nitrogen per mu is suitable. The nitrogen fertilizer should be applied deep, and combined with phosphorus and potassium fertilizer, or ternary compound fertilizer should be applied. After the application, it is necessary to cover the soil in time, reduce the loss, improve the utilization rate, and stop the topdressing 20 days before the harvest.
3. Reapply organic fertilizer. Organic fertilizers are mostly based on base fertilizers, generally 4000-5000 kg of fully decomposed organic fertilizer per acre. If the organic fertilizer is not fully decomposed, the heat generated during the continuous fermentation process causes the crop to burn, and it is easy to bring the diseased eggs in the manure into the shed, and the manure produces harmful gas in the fermentation process to harm the vegetables.
4. Nitrogen, phosphorus, potassium and trace elements are combined. At present, formulating fertilization and balanced fertilization in the cultivation of pollution-free vegetables is based on the nutritional characteristics of vegetables, the characteristics of soil fertilization and the effect of increasing the yield of fertilizers. In fertilization, the principle of fertilization combined with organic fertilizer and chemical fertilizer should be adhered to, so that the supply of nitrogen, phosphorus and potassium nutrients should be balanced, and a large number of elements and trace elements should be balanced. In addition, in the greenhouse, the topdressing method can be suitably used, such as urea, potassium dihydrogen phosphate, and trace elements such as calcium nitrate, boron, zinc, and molybdenum.

Huaxian Agricultural Technology Center; Li Dongxia
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