How to reduce fertilizer pollution to vegetables?

In recent years, due to long-term and extensive use, some of the chemical fertilizers that enter the soil have not been absorbed and utilized by crops and transferred to groundwater, resulting in pollution. So how to reduce the pollution of chemical fertilizer to vegetables?

In order to reduce the pollution of vegetables caused by fertilization, we should pay attention to the following points in fertilization:

1. Re-application of organic fertilizer will not lead to the accumulation of nitrate in vegetables, but also improve the quality of vegetables. Organic fertilizer is best applied after high temperature composting or biogas fermentation, which can kill bacteria and eggs, reduce the application amount of pesticides, and improve the yield and quality of vegetables. The vegetables grown with biogas fertilizer are the best pollution-free vegetables.

two。 No or less application of nitrate nitrogen fertilizer and compound fertilizer containing nitrate nitrogen is easy to make vegetables accumulate nitrate, so it is not suitable to be used in vegetables, ammonium nitrogen fertilizer and acyl ammonium nitrogen fertilizer can be selected, such as ammonium sulfate, ammonium bicarbonate, urea and so on.

3. Controlling the amount of nitrogen fertilizer the accumulation of nitrate in vegetables increased with the increase of nitrogen application rate. The amount of nitrogen application per mu should be controlled within 30 kg, of which 70% to 80% is used for deep application of base fertilizer and 20% to 30% for deep application of seedling fertilizer.

4. Nitrogen fertilizer should be applied early and deep as base fertilizer or topdressing at seedling stage, which is beneficial to the early growth and rapid development of vegetables and reduce the accumulation of nitrate in soil and vegetables. The deep application of nitrogen fertilizer to the soil layer of 10 cm to 15 cm can reduce the nitrogen loss and improve the nitrogen use efficiency. In the deep soil, the soil air is in the condition of anaerobic, and the nitrification is slow, which can reduce the nitrate accumulation of vegetables.

5. Due to the soil with high fertility and rich organic matter, vegetables are easy to accumulate nitrate, so nitrogen fertilizer should be prohibited or less applied. In the low fertilizer vegetable field, the nitrate accumulation of vegetables is relatively light, so nitrogen fertilizer and organic fertilizer can be applied to improve soil fertility. General vegetable fields, such as soil testing and balanced fertilization, are not only conducive to high quality and high yield, but also make it difficult for vegetables to accumulate nitrate, but also help to improve soil fertility. The high temperature in summer and autumn is not conducive to the accumulation of nitrate, so appropriate amount of nitrogen fertilizer can be applied. Low temperature in winter and spring, weak light, nitrate reductase activity decreased, easy to accumulate nitrate, should not apply or less nitrogen fertilizer.

6. Due to the fertilization of different kinds of vegetables, the degree of nitrate absorption and accumulation is different, Chinese cabbage and green leafy vegetables are easy to accumulate nitrate and can not use nitrate fertilizer; eggplant, fruit and root vegetables have less nitrate accumulation and can be applied properly, but the application of nitrate fertilizer should be stopped 15-30 days before harvest.

7. Foliage vegetables must avoid foliar spraying nitrogen fertilizer as foliar fertilizer in direct contact with the air, ammonium ions are easy to turn into nitrate ions are absorbed by leaves, nitrate accumulation increases. Therefore, foliar spraying of nitrogen fertilizer should be prohibited in the production of pollution-free leafy vegetables, especially one month before harvest.

8. Irrigating vegetables without sewage is easy to be polluted. All sewage discharged from factories and mines, which contains more toxic substances such as chlorine, arsenic, tin and lead, should be prohibited from being used to water vegetables. Urban domestic sewage should be treated innocuously. After killing germs and eggs, it should be mixed with clean water.