Non-polluted vegetables refer to vegetables whose harmful substances (such as pesticide residues, heavy metals, nitrites, etc.) are controlled within the permissible range of the state and are not harmful to human health after consumption. However, vegetables are crops that are easy to enrich and retain nitrates, heavy metals and pesticides. Vegetable farmers are blindly and over-utilized with fertilizers, pesticides, and various sources of pollution for the pursuit of yield, which is the main cause of vegetable pollution. Therefore, in the production of vegetables, reasonable fertilization should be done, so that the content of harmful substances in vegetables is controlled within the standards set by the state, achieving the goal of high yield, high quality and no pollution.
1. Rational application of nitrogen fertilizer
1. Controlling the amount of nitrogen fertilizer A reasonable amount of nitrogen fertilizer can not only improve the yield of vegetables, but also improve the quality of vegetables. Therefore, rational application of nitrogen fertilizer is one of the main problems in the production of pollution-free vegetables. The application amount of nitrogen fertilizer should be properly controlled. The low-nitrate nitrogen fertilizer ammonium sulfate should be used to reduce the nitrate content in vegetables. The ratio of inorganic nitrogen to organic nitrogen is 1:1 in the application of nitrogen fertilizer.
2. Using the "attack and tail control" nitrogen application technique, the plant does not apply quick-acting nitrogen fertilizer in the late growth stage, and the short-term vegetables use 70% of the nitrogen fertilizer as the base fertilizer; the long-term vegetables use 40% of the total nitrogen fertilizer as the base fertilizer, and the deep application of the base fertilizer is adopted. , the method of topdressing or applying.
Second, increase the application of phosphorus and potassium fertilizer
Phosphate fertilizer can provide phosphorus nutrients for vegetables, inhibit the activity of heavy metals such as cadmium, lead, zinc and arsenic, reduce toxicity, reduce harm, and increase potassium fertilizer, which can reduce the accumulation of nitrate in vegetables and improve the quality of vegetables. Potassium is also called "quality element". When potassium is applied to vegetables, the content of vitamin C and sugar in the fruit is significantly increased, and the storage durability is also improved. Studies have shown that the application of potassium fertilizer on the basis of nitrogen fertilizer and phosphate fertilizer can reduce the nitrate content of spinach, and the nitrate content of lettuce and celery also decreases with the increase of potassium application rate. The ratio of nitrogen, phosphorus and potassium is 1:0.2:0.5 for short-term dishes and 1:0.5:0.6 for long-term dishes.
Third, increase the application of organic fertilizer
Adding fully decomposed organic fertilizer can increase the soil organic matter content, enhance the soil's adsorption capacity and complexing ability, and effectively curb the toxicity of cadmium and lead to vegetable crops. At the same time, applying organic fertilizer can reduce nitric acid more than chemical fertilizer. The salt content reduces the nitrate content by about 45%. Some tests have shown that: celery applied organic fertilizer, the nitrate content is 744mg/kg, while the chemical fertilizer, the nitrate content is as high as 1480mg/kg. Therefore, organic fertilizer has little pollution to the vegetable soil environment.
Fourth, interplanting green manure
Interplanting green manure such as alfalfa is an effective way to maintain and improve soil fertility. Through the self-fixing nitrogen of legume green manure, more abundant nitrogen resources can be obtained, and the soil organic matter content can be improved. At the same time, the agglomeration structure of the soil can be improved through the activity and decomposition of microorganisms.
5. Promote balanced fertilization technology
According to soil fertility and vegetable yield, as well as the characteristics of different vegetables, the scientific and rational application of chemical fertilizers, the development of special fertilizers, and the promotion of root dressing technology. For example, spraying molybdenum fertilizer can reduce the nitrate content in lettuce, Chinese cabbage and spinach.
1. Rational application of nitrogen fertilizer
1. Controlling the amount of nitrogen fertilizer A reasonable amount of nitrogen fertilizer can not only improve the yield of vegetables, but also improve the quality of vegetables. Therefore, rational application of nitrogen fertilizer is one of the main problems in the production of pollution-free vegetables. The application amount of nitrogen fertilizer should be properly controlled. The low-nitrate nitrogen fertilizer ammonium sulfate should be used to reduce the nitrate content in vegetables. The ratio of inorganic nitrogen to organic nitrogen is 1:1 in the application of nitrogen fertilizer.
2. Using the "attack and tail control" nitrogen application technique, the plant does not apply quick-acting nitrogen fertilizer in the late growth stage, and the short-term vegetables use 70% of the nitrogen fertilizer as the base fertilizer; the long-term vegetables use 40% of the total nitrogen fertilizer as the base fertilizer, and the deep application of the base fertilizer is adopted. , the method of topdressing or applying.
Second, increase the application of phosphorus and potassium fertilizer
Phosphate fertilizer can provide phosphorus nutrients for vegetables, inhibit the activity of heavy metals such as cadmium, lead, zinc and arsenic, reduce toxicity, reduce harm, and increase potassium fertilizer, which can reduce the accumulation of nitrate in vegetables and improve the quality of vegetables. Potassium is also called "quality element". When potassium is applied to vegetables, the content of vitamin C and sugar in the fruit is significantly increased, and the storage durability is also improved. Studies have shown that the application of potassium fertilizer on the basis of nitrogen fertilizer and phosphate fertilizer can reduce the nitrate content of spinach, and the nitrate content of lettuce and celery also decreases with the increase of potassium application rate. The ratio of nitrogen, phosphorus and potassium is 1:0.2:0.5 for short-term dishes and 1:0.5:0.6 for long-term dishes.
Third, increase the application of organic fertilizer
Adding fully decomposed organic fertilizer can increase the soil organic matter content, enhance the soil's adsorption capacity and complexing ability, and effectively curb the toxicity of cadmium and lead to vegetable crops. At the same time, applying organic fertilizer can reduce nitric acid more than chemical fertilizer. The salt content reduces the nitrate content by about 45%. Some tests have shown that: celery applied organic fertilizer, the nitrate content is 744mg/kg, while the chemical fertilizer, the nitrate content is as high as 1480mg/kg. Therefore, organic fertilizer has little pollution to the vegetable soil environment.
Fourth, interplanting green manure
Interplanting green manure such as alfalfa is an effective way to maintain and improve soil fertility. Through the self-fixing nitrogen of legume green manure, more abundant nitrogen resources can be obtained, and the soil organic matter content can be improved. At the same time, the agglomeration structure of the soil can be improved through the activity and decomposition of microorganisms.
5. Promote balanced fertilization technology
According to soil fertility and vegetable yield, as well as the characteristics of different vegetables, the scientific and rational application of chemical fertilizers, the development of special fertilizers, and the promotion of root dressing technology. For example, spraying molybdenum fertilizer can reduce the nitrate content in lettuce, Chinese cabbage and spinach.
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