1. Implementing formula fertilization. According to the characteristics of vegetable fertilizer requirement and soil fertilizer supply in different greenhouses, the appropriate amount of nitrogen, phosphorus, potassium and trace elements and corresponding fertilization techniques were determined. The maximum demand period of nitrogen, phosphorus and potassium for greenhouse vegetables were 75-140 days after planting, 30-52 days for tomatoes and 30-60 days for sweet peppers. Other vegetables need little trace elements, but they are indispensable. When spraying micronutrient fertilizer on the leaves, the dosage standard should be set properly. Pay attention to leafy vegetables do not spray fertilizer, so as not to increase the nitrate content.
2. Strictly control the amount of nitrogen fertilizer. Nitrogen fertilizer is an indispensable fertilizer in vegetable production, but it can not be applied excessively. In order to make vegetables meet the national and international pollution-free standards, it is necessary to reduce the nitrate content in vegetables. In order to reduce the application of nitrogen fertilizer, it should be decided according to different vegetable fertilizer requirements, generally 10-12 kg of pure nitrogen per mu is appropriate; nitrogen fertilizer should be applied in depth, and combined with phosphorus and potassium fertilizers or the application of ternary compound fertilizer, timely cover soil after application, it is best to use chemical fertilizer cannula infiltration or drip irrigation under plastic film to apply root, reduce loss and extract. High utilization rate, stop topdressing 20 days before harvest.
3. It is forbidden to apply nitrate nitrogen fertilizer. Ammonium nitrate, ammonium sulfate, phosphate nitrate, potassium nitrate and compound fertilizer containing nitrate nitrogen are easy to accumulate nitrate in vegetables after application. In addition, chloride-containing fertilizers such as potassium chloride and ammonium chloride should not be applied. Chloride ions can reduce the content of starch and sugar in vegetables, make the quality worse and the yield lower. Moreover, residues in the soil can easily cause soil decalcification and hardening. Magnesium sulfate, ammonium sulfate and other fertilizers, applied to the soil, decomposed sulfate ion, not easy to be absorbed by vegetables and remain in the soil, endangering vegetable growth. It is forbidden to use ammonium bicarbonate because it is easy to volatilize a large amount of ammonia and cause ammonia damage.
4. Applying ecological organic fertilizer. A series of special fertilizers will be formed if different elements are added to the ecological organic fertilizer produced by fermentation of livestock and poultry manure. The organic matter content of eco-organic fertilizer can reach 45%. It can fix nitrogen, dissolve phosphorus, dissolve potassium in vegetables, and decompose pesticide and chemical fertilizer residues. Fermentation matures in spring, summer and autumn in 5-6 days, and in winter in 7-10 days. Generally, when the temperature in the compost rises to 80 C for 1 to 3 days, it can kill E. coli and insect eggs, eliminate the stink of chicken manure, and then the compost becomes loose and dry, full of white mycelia, and two days later, it can produce a kind of liquor yeast fragrance.
5. Restrict the use of hormones. Some vegetable farmers do not talk about the quality of vegetable. In order to pursue high yield, early maturity and early market, they use hormones such as gibberellin, ethephon and Paclobutrazol to promote growth and ripening, which greatly reduces the quality of vegetable. People's long-term consumption is harmful to their health.