Green vegetables require fertilization technology: based on organic fertilizer to increase soil fertility level; insert legume crops to increase soil nitrogen content, reduce the amount of chemical nitrogen fertilizer; strictly control nitrogen fertilizer time, control the nitrate content of the vegetable. In the process of producing vegetables that meet the green food standards, there should be a correct understanding of chemical fertilizer application.
There is no conflict between green food and fertilizer application. Do not oppose the use of chemical fertilizers to green foods. Chemical nitrogen fertilizers are inorganic nitrogen sources that vegetables can directly absorb. Organic fertilizers, after being decomposed by microorganisms, convert organic nitrogen into inorganic nitrogen. It is also used to supply inorganic nitrogen to vegetables. Absorbed. Therefore, it is considered that "applied vegetable fertilizers are not green food standard vegetables," and that "the application of organic fertilizers to vegetables is the standard for green food." This is not correct. In fact, some vegetables that use large amounts of organic fertilizers have a lot of nitrates in their bodies.
Appropriately control the amount of nitrogen fertilizer. In order to ensure that the green food standard vegetables have better yield and economic benefits, it is necessary to properly apply nitrogen fertilizer on the basis of applying organic fertilizer, but it must be controlled. In the current situation where green food vegetables are not subject to quality arguments, it is difficult to solve the contradiction between quality and yield, yield and benefits without applying chemical nitrogen fertilizer. It is also difficult for farmers to accept.
Strictly grasp the top dressing time of nitrogen fertilizer. The nitrate content of vegetable crops is constantly changing. Because the nitrogen that enters the vegetable body is further converted into amino acids during the metabolic process, and the protein is synthesized. According to research, nitrate content in vegetables gradually decreases with the increase of nitrogen fertilizer application time. For example, rapeseed with 5000 kg organic fertilizer per acre and top dressing with 25 kg ammonium sulfate, the nitrate content in rapeseed was reduced from 5372 mg/kg after top dressing for 3 days to 877.4 mg/kg after 14 days, and 653.8 after 18 days. Mg/kg, has met the green food recommendation. Therefore, from safety considerations, the top dressing time for green food vegetables should be 15-20 days before harvesting. In addition, the combination of nitrogen fertilizer and potassium fertilizer can promote the synthesis of protein and reduce the nitrate content in the body.
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