1. Re-application of organic fertilizers Organic fertilizers must be applied after high-temperature stacking or biogas fermentation, which can kill pathogens and eggs, reduce the application rate of pesticides, and increase the yield and quality of vegetables. Vegetables that use biogas fertilizer are the best pollution-free vegetables.
Second, the scientific application of nitrogen fertilizer 1. Nitrogen fertilizer should be applied early as a base fertilizer or seedling application, which is conducive to the early growth of vegetables, which is conducive to reducing the accumulation of nitrate in soil and vegetables.
2. Nitrogen fertilizer Deep application of nitrogen fertilizer to the soil layer of 10-15 cm can reduce the loss of nitrogen, increase the utilization rate of nitrogen fertilizer, and reduce the accumulation of nitrate in vegetables.
3. Controlling the amount of nitrogen fertilizer The accumulation of nitrate in vegetables increased with the increase of nitrogen fertilizer application rate. The amount of nitrogen applied per mu should be controlled within 30 kg, 70-80% of which should be applied as base fertilizer and 20-30% as deep application of seedling fertilizer.
4. No or little application of nitrate nitrogen fertilizer can choose ammonium nitrogen fertilizer and ammonium amide fertilizer, such as ammonium sulfate, ammonium hydrogencarbonate, urea and so on.
3. Fertilization for vegetables 1. Different types of vegetables are fertilized by vegetables, and the degree of absorption and accumulation of nitrate is different. Cabbage and green leafy vegetables tend to accumulate nitrates, and nitrates cannot be used; canola, fruits and root vegetables Vegetable-like vegetables have less accumulation of nitrate and can be applied properly, but the application of nitrate-nitrogen fertilizer should be stopped within 15-30 days before harvest.
2. Leafy vegetables are not suitable for foliar fertilization. Leafy leaves are sprayed with nitrogen fertilizer, which is directly in contact with air. Ammonium nitrogen is easily converted into nitrate nitrogen and absorbed by leaves. Other kinds of fertilizers are sprayed from the foliage and are also likely to contaminate the leaves.
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