Misunderstanding in the Application of Chemical Fertilizer for vegetables in greenhouse

When inorganic fertilizer is applied to vegetables in greenhouse, there are often the following misunderstandings, which not only reduce the fertilizer efficiency, but also bring some negative effects, which is worthy of attention.

1. Ammonium bicarbonate and ammonium sulfate were applied in greenhouse in winter. Ammonium bicarbonate will volatilize a large amount of ammonia after application, which is disadvantageous to the growth of vegetables; ammonium sulfate is a physiological acid fertilizer, which will increase the acidity of the soil. When applying ammonium bicarbonate, attention should be paid to deep application. Generally, a ditch with a depth of 10 centimeters is opened at 8 centimeters away from the vegetable rhizome, and the soil is strictly covered after application, which can increase the utilization rate by 10% to 30%.

two。 Apply more diammonium phosphate in winter. Vegetables need a lot of nitrogen and potassium and less phosphorus. For example, the ratio of nitrogen, phosphorus and potassium needed by eggplant is 3 ∶ 1 ∶ 4, cucumber is 3 ∶ 1 ∶ 10, tomato is 6 ∶ 1 ∶ 12, etc. Diammonium phosphate contains 18% nitrogen, 46% phosphorus and no potassium, so it is not suitable to use diammonium phosphate in greenhouse vegetables. In addition, it should be noted that diammonium phosphate should not be mixed with alkaline fertilizers such as plant ash, so as not to cause ammonia volatilization and ammonia damage.

3. Potassium fertilizer was applied in the later stage of growth. Generally, vegetables need more potassium before and after flowering, and then decrease gradually. The application of potassium fertilizer in the later stage will significantly reduce the utilization rate of potassium and waste fertilizer.

4. Fertilize under dry conditions. Vegetables like water, fertilizing when the soil is dry, not only the fertilizer effect can not be brought into full play, but also the concentration of soil solution will suddenly increase, which is easy to make vegetables burn roots. Therefore, fertilization in greenhouse should be combined with irrigation, ditch fertilization should be opened, fertilizer should be buried and then irrigated, or flushed with water.

5. Iron fertilizer is applied to the soil. Iron is easily fixed and transformed into insoluble compounds by soil and can not be absorbed and utilized by vegetables, so foliar spraying is the best way to apply iron fertilizer in greenhouse. 0.1%-0.3% ferrous sulfate solution can be evenly sprayed on the leaves of vegetables.

Zhang Yun of Xinji Agricultural Technology Center