Principles of fertilizing vegetables in greenhouses

Implement formula fertilization

According to the fertilizer requirements of different vegetables and the status of soil fertilizer, determine the appropriate amount of nitrogen, phosphorus, potassium and trace elements and the corresponding fertilization technology. The maximum demand periods for nitrogen, phosphorus, and potassium of greenhouse vegetables are: 75 to 140 days after planting for cucumber, 30 to 52 days for tomato, and 30 to 60 days for sweet pepper. Although other vegetables require very little trace elements, they are indispensable. When using micro-fertilizer foliar sprays, the dosage standards should be set. Be careful not to spray fertilizer on leafy vegetables to avoid increasing nitrate content.

Strictly control the amount of nitrogen fertilizer

Nitrogen fertilizer is an indispensable fertilizer in vegetable production, but it cannot be over-applied. To make vegetables reach national and international pollution-free standards, the nitrate content in vegetables must be reduced. To reduce the amount of nitrogen fertilizer applied, it should be determined according to the amount of fertilizer required for different vegetables, generally 10-12 kg of pure nitrogen per mu is appropriate; nitrogen fertilizer should be applied in depth, and it should be used in conjunction with phosphorus and potassium fertilizers or ternary compound fertilizers. Cover the soil in time after application, and use fertilizer intubation or combined drip irrigation under the film to apply to the roots to reduce loss and improve utilization. Stop topdressing 20 days before harvest.

Prohibit the application of nitrate nitrogen fertilizer

Ammonium nitrate, ammonium sulfate, nitrophosphate, potassium nitrate and compound fertilizers containing nitrate nitrogen are easy to make vegetables after application.

Vegetables accumulate nitrate. In addition, it is not suitable to use chlorinated fertilizers such as potassium chloride and ammonium chloride. Chloride ions can reduce the starch and sugar content in vegetables, make the quality worse, reduce the yield, and the residue in the soil can easily cause soil decalcification and cause compaction. . Fertilizers such as magnesium sulfate and ammonium sulfate are applied to the soil, and the decomposed sulfate ions are not easily absorbed by vegetables and stay in the soil, which endangers the growth of vegetables. It is forbidden to use ammonium bicarbonate, because it easily volatilizes a large amount of ammonia gas, which can easily cause ammonia damage.

Apply ecological organic fertilizer

Ecological organic fertilizer produced by fermenting livestock manure will form a series of special fertilizers if different elements are used in a targeted manner. The organic matter content of ecological organic fertilizer can reach 45%, which can fix nitrogen, dissolve phosphorus and potassium on vegetables, and can also decompose residues of pesticides and fertilizers. It takes 5-6 days to mature in spring, summer and autumn, and 7-10 days in winter. Generally, it will be piled for 1 to 3 days, and the temperature in the pile will rise to 80℃, which can kill E. coli and insect eggs and eliminate the odor of chicken manure. Later, the compost will become loose, dry and full of white hyphae. Kind of *** song fragrance.

Limit the use of hormones

Some vegetable farmers do not pay attention to the quality of vegetables. In order to pursue high yield, early maturity, and market in the morning, use hormones such as gibberellin, ethephon, paclobutrazol and other hormones to accelerate the growth and ripening, which greatly reduces the quality of vegetables. Long-term consumption is not good for health.