Basic principles for the production of green vegetables for fertilization

Green vegetables are a kind of green food. They refer to pesticide residues and nitrate content residues in vegetables that are lower than the national or international standards when pesticides and fertilizers are used in the production process. Therefore, green products are relative, not absolute.

Assessing green products also depends on other indicators: such as pollution of the environment, soil, and groundwater during the production of green products, and energy conservation.

Green products are safe and healthy for people in the process of use, and are harmless to the environment; green products are not polluted by the environment during the process of extinction and can be rapidly degraded. According to China's green vegetable production standards, the production of green vegetables fertilization should follow the following three basic principles:

First, strictly control the amount of nitrogen fertilizer

In order to ensure high yield and economic benefits of green vegetables, proper application of nitrogen fertilizer is necessary on the basis of applying organic fertilizer, but it is necessary to strictly control the dosage to solve the contradiction between quality and output, yield and benefit. At the same time, pay attention to the choice of nitrogen fertilizer varieties, the accumulation of nitrate in vegetables is reduced by the influence of sodium nitrate, ammonium nitrate, urea, ammonium chloride.

Second, vigorously balanced fertilization

Because of the combination of various fertilizers, it is easier to reduce the nitrate content in vegetables than the single application of nitrogen fertilizer. Nitrogen and phosphorus combined with spraying micro-fertilizer can reduce the content of nitrate in vegetables, especially with potassium fertilizer, which can promote protein synthesis and reduce nitrate content in the body.

Third, strictly control the time of application of nitrogen fertilizer

The nitrate content of vegetable crops is constantly changing. Nitrogen entering the vegetable body is further converted into protein during metabolism. According to the research, with the change of nitrogen fertilizer application time, the nitrate content in vegetables has gradually decreased. After 18 days of topdressing, the nitrate content in the vegetables has met the recommended standards for green food. Therefore, the top dressing time of green vegetables should be 15~20 days before harvesting.

(Feng Dajun, Xinfeng Information Station, Longmu Town, Da'an City, Jilin Province)