There are two main ways that fertilization can contaminate vegetables: First, through the direct use of harmful substances contained in fertilizers, such as heavy metals, pathogenic microorganisms, and poisonous gases, to contaminate vegetables or soil; and secondly, to infuse vegetables with large amounts of nitrogen fertilizers. Over-accumulation of nitrate. In order to reduce the pollution of vegetables caused by fertilization, the following points should be noted in fertilization: Reapply organic fertilizer. Organic fertilizer does not lead to the accumulation of nitrates in vegetables, but also improves the quality of vegetables. The organic fertilizer is preferably applied after high-temperature stacking or biogas fermentation and decomposing, which can kill bacteria and eggs, reduce the amount of pesticides, and increase the yield and quality of vegetables. The use of biogas fertilizer to grow vegetables is the best pollution-free vegetables. Do not apply or less apply nitrate nitrogen fertilizer. Nitrate-nitrogen fertilizers and compound fertilizers containing nitrate nitrogen can easily accumulate nitrates in vegetables, so they should not be used on vegetables. Ammonium and nitrogen-containing ammonium fertilizers such as ammonium sulfate, ammonium bicarbonate, and urea can be used. Control the amount of nitrogen fertilizer. Nitrate accumulation in vegetables increased with the amount of nitrogen fertilizer applied. The amount of nitrogen applied per acre should be controlled within 30 kilograms, 70%-80% of which should be applied as a deep application of base fertilizer, and 20%-30% should be used as a deep application of seedling fertilizer. Nitrogen fertilizer should be applied early. The application of nitrogen fertilizer as base fertilizer or top-dressing fertilizer at the seedling stage is conducive to the rapid growth of vegetables as soon as possible, which will help reduce the accumulation of nitrate in soil and vegetables. Deep application of nitrogen fertilizer to the soil layer of 10-15 cm can reduce the loss of nitrogen and increase the nitrogen use efficiency. In deep soils, soil air is in an off-gassing condition, and nitrification is slow, which can reduce the accumulation of nitrates in vegetables. Fertilize due to the season and season. High fertility, soil rich in organic matter, vegetables are prone to nitrate accumulation, should be banned or less nitrogen fertilizer. In low-fertilizer vegetable fields, nitrate accumulated in vegetables is lighter, and nitrogen fertilizer and organic fertilizer can be applied to fertility. In general vegetable fields, such as adopting balanced fertilization for soil testing, it is not only beneficial to high quality and high yield, but also makes it difficult for vegetables to accumulate nitrate, and is also conducive to fertility. High temperatures in summer and autumn are not conducive to the accumulation of nitrates, and appropriate nitrogen fertilizers may be used. In winter and spring, the temperature is low, the light is weak, the activity of nitrate reductase is decreased, and nitrate is easy to accumulate. No nitrogen fertilizer should be applied or reduced. Fertilizer for vegetables. Different kinds of vegetables have different degrees of absorption and accumulation of nitrates. Cabbage and green leafy vegetables are likely to accumulate nitrates, and nitrate-nitrogen fertilizers cannot be used. Solanaceous vegetables, fruit vegetables and root vegetables produce less accumulation of nitrates. Appropriate application, but application of nitrate fertilizer should be stopped 15-30 days before harvest. Leaf vegetables should not be foliar spray nitrogen fertilizer. Nitrogen fertilizers are used as leaf fertilizers to be in direct contact with air. Ammonium ions tend to become nitrate ions and are absorbed by the leaves. Nitrate accumulation increases. Therefore, foliar spraying of nitrogen fertilizers should be forbidden in the production of non-polluted leafy vegetables. In particular, it is not possible to spray nitrogenous fertilizer on foliar one month before harvest. Do not use sewage water. Sewage watered vegetables, easily contaminated. Wastewater discharged from factories and mines contains more toxic substances such as chlorine, arsenic, tin and lead, and should not be used for watering vegetables. Urban sewage should be treated in a harmless manner. After killing germs and eggs, it is mixed with clear water. Pickled Beefsteak,Frozen Pickled Beefsteak,Seasoned Pickled Beef Cubes,Fillet Steak ZHOUSHAN GENHO FOOD CO.,LTD , https://www.genho-food.com
Scientific fertilization reduces pollution
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