I believe that many people have such an experience, every time they return to the city from their hometown, relatives and friends will load a lot of agricultural products, vegetables and fruits, all-encompassing, by the way, "we grow this dish ourselves, there is no medicine, safer and healthier than in the city." But is that really the case? The fact is that no matter where the vegetables, their safety is closely related to the planting environment and planting methods, today Xiaobian will talk about the "vegetable basket" safety of those things.
The main factors affecting the safety of vegetable food
1. Environmental pollution
China's industrialization process is gradually accelerating, especially industrial plants are usually built in rural areas or suburbs, and these places are also vegetable planting areas, so vegetables will be seriously polluted. For example, water pollution, many enterprises will not have the standard treatment of wastewater into the surrounding water sources, the discharge of urban domestic wastewater will also have an impact on water quality, resulting in different degrees of water pollution, seriously affecting the safety of vegetables.
Soil contamination can cause vegetables to exceed heavy metals and accumulate through the food chain into the human body, thus affecting health. The problem of soil heavy metal pollution caused by industrial "three wastes" emissions, municipal solid waste dumping, agrochemical input and atmospheric sedimentation has aroused widespread concern in the whole society. In 2014, the Ministry of Environmental Protection and the Ministry of Land and Resources jointly issued a national soil pollution survey communiqué, showing that the soil exceeding the standard rate of arable land was 19.4%, of which 1.1% were heavily polluted. Specifically, soil pollution is large on the side of highways, old factories, backfill soil, wasteland and other places.
2. Pesticide residues
Vegetables are susceptible to pests and diseases, so growers often use pesticides to improve the quality of vegetables, which leads to pesticide residue problems. There are two main reasons for pesticide residues: (1) There is no standard for the use of pesticides. In order to prevent pests and diseases, many growers will use some pesticides with strong toxicity without authorization, which increases the residual pesticide content of vegetables.
(2) Frequent use of pesticides. The frequency of pesticide use is too high, which may lead to insect resistance, insecticidal efficiency is reduced, and more pesticides need to be used, which is caught in a vicious circle. In the process of agricultural testing, it can be seen that many vegetables have serious pesticide content exceeding the standard, and the number of qualified products is small.
3. Fertilizers and biological pollution
The reason for the excessive heavy metal content and nitrite content of vegetables is mainly the improper use of chemical fertilizers. Fertilizers contain a large number of heavy metal elements, if the use of chemical fertilizers can not be reasonably controlled, it will lead to a substantial increase in the content of vegetable nitric acid salt. The degree of harm of nitrite is even higher than that of pesticides, which will have an irreversible impact on human kidney function.
Biological pollution is a kind of fertilizer pollution in the planting process, many people will use human and animal manure as fertilizer, but this method has obvious defects, which can easily lead to biological pollution. Feces have not been effectively treated, and the harmful substances in it will affect the quality of vegetables, which can easily lead to vegetables carrying infectious bacteria, which in turn will affect people's health.
Precautions for vegetable cultivation
1. Rational use of soil conditioners
Select the appropriate planting area, avoid planting areas in industrial areas or areas with heavy urban pollution, and then through the rational use of soil improvement products, improve the physical properties such as soil moisture content, change the chemical properties such as soil pH, regulate the activity of soil microorganisms, etc., thereby reducing the bioavailability of heavy metals in the soil, reducing soil heavy metals, reducing pollution, and reducing the heavy metal content of vegetables.
2 Rational application of organic fertilizer
The irrational use of chemical fertilizers can easily lead to soil compaction, reduce nutrient absorption and increase planting costs. Technologies such as "soil testing and formula fertilization", "organic fertilizer substitution" and "deep application of chemical fertilizers" should be implemented, the structure of fertilizer use should be adjusted and improved, the organic fertilizer after decomposition should be used, and the amount of chemical fertilizer should be controlled, so as to improve soil health, achieve chemical fertilizer reduction and efficiency, and ensure the quality of vegetable products. After fermentation, the organic fertilizer has been detoxified, and harmful bacteria and insect eggs have been killed, providing long-lasting fertility in vegetable growth, and the fertilizer effect is also strong, which is the driving force for the growth of vegetables.
3 Green prevention and control technology of diseases and insect pests
Vegetables are susceptible to diseases and insect pests, and diseases and insect pests are "invincible" and difficult to control, resulting in a high residual content of pesticide residues in vegetables. Safe planting of vegetables can be monitored or visually monitored by color plates at the seedling stage and after colonization, and when pests are found, corresponding green control measures are adopted to prevent and control vegetable pests through natural enemy insect release technology and biopesticides. Whitefly pests can be controlled by natural enemies such as lisa aphid wasps, paddle horn aphid wasps, East Asian flower aphids, and blind bugs; pest mites can be controlled by releasing Chilean small plant mites, California new small pig mites, cucumber new small pigtail mites, pasteurized new small pigtail mites, etc.; the control of aphid pests can use natural enemy species: aphid cocoon bees, ladybirds, grasshoppers, and aphids.
Biopesticides are friendly to the environment, not easy to lead to drug resistance, pesticide residues and soil compaction problems, can prevent the outbreak of diseases and insect pests, and some biopesticides also promote the growth of vegetables. Carvacrol can be used to deal with common vegetable diseases such as gray mold, amino oligosaccharides and cnidine can be used for powdery mildew, berberine can be used for brown spot disease, and allicin can be used for bacterial diseases such as ulcer disease. Vegetables in the occurrence or occurrence of pests in the early stage of administration, whiteflies can choose wax tick rotifers, coccidioides albicans, mineral oil and other agents; pest mites can choose mineral oil, quinoa alkali and other agents; aphids can choose phyressine, rotenone, pyrethroids, matrine and other agents; thrips can choose polybactericides and other agents; lepidopteran pests can choose Bt., short stable bacillus and polyhedrovirus preparations.
summary
Vegetable food safety is closely related to the vegetable planting environment and planting methods, and the crops grown by hard irrigation may be of poor quality due to environmental pollution and other issues. In response to common agricultural problems such as environmental pollution and pesticide residues, the use of green prevention and control technology, the application of organic fertilizers, and biopesticides for large-scale vegetable production can promote the "reduction and efficiency" of pesticides and chemical fertilizers, improve the quality of vegetables, increase the economic benefits and safety of vegetable planting, and is also the development direction of vegetable planting and agriculture in the future.