Vegetables are indispensable foods for people's daily life. However, when vegetables are grown, improper use of fertilizers and lax grasps often lead to poor quality and quality of vegetables. Chemicals and toxic substances are severely exceeded and affect human health. After investigation, the author believes that in order to truly produce pollution-free vegetables, the use of fertilizer should be done with “five unfavorableâ€. Unsuitable to use raw manure The so-called raw manure is a variety of organic fertilizers without thorough decomposing, such as manure, manure and urine. These manures are the bulk fertilizers in vegetable cultivation, and they are also the most common, most common and most easily accumulated fertilizer. If these fertilizers are not matured without stacking, the eggs, bacteria, and weed seeds in the fertilizer will not be killed by high temperatures. The eggs and bacteria will directly contaminate the vegetables and affect people's health. At the same time, the seeds of weeds grow at any time. Fighting for water with vegetables will also affect the growth of vegetables. Unfavorable use of waste fertilizers Current waste has become a major public hazard in the city, and the use of waste as fertilizer to grow vegetables in some areas has become a reality. Garbage can be divided into three categories, one is household waste. Such as the kitchen waste soup, rotten vegetables, dead leaves and grass, these garbage can be used as compost, the growth of vegetables can play a role in increasing nutrients; Second, industrial waste. This kind of garbage contains bricks, sand, stones, cement, plastic bags, glass chips, etc. Once it is turned into the soil, it neither has the effect of improving the soil, nor does it provide nutrients for the growth of vegetables, but it also easily leads to soil deterioration, and even to grass. The situation; Third, the hospital garbage. Although it contains leftover soup, rotten rice, and fruit, it also contains waste from various patients. Because the patients are mostly carriers of bacteria, some pathogens are not easily killed through general treatment. If they are used as vegetable fertilizers, they will cause direct pollution to the vegetables. This directly harms human health. The application of nitrate nitrogen fertilizers to fertilizers containing nitrate nitrogen in chemical fertilizers is mainly composed of ammonium nitrate and compound fertilizers containing nitrate nitrogen. These fertilizers, when applied to vegetable fields, produce large amounts of nitrate ions, and vegetables need to absorb large amounts of nitrogen during growth. Fertilizers, nitrate ions are needed for vegetable growth, which increases the nitrate content of vegetables. This vegetable can be converted into nitrite by entering the human gastrointestinal tract. Nitrite is a very toxic substance. And carcinogens. Therefore, the use of ammonium nitrogen fertilizers such as urea, ammonium sulfate, ammonium bicarbonate, etc. should be applied to vegetable cultivation, and basic fertilizer must be re-used to apply fertilizer early. Furthermore, chemical fertilizers should not be applied before vegetables are harvested to prevent vegetables from growing. Excessive chemical substances. Twenty days before picking, it is not appropriate to spray nitrogen on the leaves. There are quite a few vegetables that are eaten by the leaves, such as cabbage, rapeseed, Chinese cabbage, spinach, cabbage, leeks and garland chrysanthemum. If the foliage is sprayed with nitrogen fertilizer solution during its growth, the photosynthesis of the plant can make the leaf color fresh, bright and bright, and will not increase the content of chemical substances in the leaves due to the application of foliar fertilizer, but if The application of nitrogen fertilizer solution to the foliage within the first 20 days will not only help the growth of the vegetables, but also increase the content of nitrate in the leaves, and eventually make the chemical substances in the vegetables seriously exceed the standards. In addition to this "nitrogen-fertilizer", due to the loss of balance between nitrogen and carbon, the moisture content of vegetables increases, and the quality of the vegetables deteriorates. This is not only resistant to storage, but also extremely rot. It is not appropriate to water contaminated water. The saying goes: Water dish, water dish, waterless dish, watering vegetables is a matter of course. Watering vegetable fields requires pouring clean well water or unpolluted rivers, lakes and potholes. Some industrial waste water, bath water, sewage from hospitals or medical research institutes, some contain mercury, some contain cyanide, some contain a large amount of lye, and some contain contagious germs. If the wastewater is used to water vegetables, In addition to directly causing the pollution of vegetables, it can also destroy the structure of the soil, making the fertile soil worse, and losing the value of planting.
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