What are the advantages of foliar fertilization? How to improve the effect of foliar fertilization?

Foliar fertilization can make nutrients enter the human body from leaves and participate in crop metabolism and organic synthesis. Compared with soil fertilization, it has the following five advantages: fast absorption of ①. Spraying leaves of apples and pineapples with urea can absorb 50% after 1-4 hours; spraying leaves of cucumbers, broad beans, tomatoes and bananas with urea can also absorb 50% after 1-6 hours. However, it takes 3 to 5 days for urea to be applied in soil, and the fertilizer use efficiency of ② is high. According to the study, the utilization rate of foliar spraying boron fertilizer is about 8 times that of base fertilizer; ③ can avoid the fixation of phosphorus, iron, zinc and other fertilizers in the soil; ④ can supplement nutrients in time when crop roots are subjected to environmental stress (such as salt damage, water damage, drought, etc.), or when crops have special nutritional requirements in a certain period; ⑤ can improve the quality of agricultural products.

Although extra-root topdressing has many advantages, it is limited by factors such as low suitable concentration range and more labor cost. when crops need a large amount of fertilizer, they have to be supplied by soil fertilization in order to meet the nutrient requirements of crops during the whole growth period. Therefore, extra-root fertilization can only be an auxiliary fertilization measure.

Attachment: how to improve the effect of foliar fertilization?

The effect of foliar fertilization is related to the type of spraying crops, spraying position, spraying concentration, spraying time and other factors. Types of crops sprayed with ①. Dicotyledons such as cotton, tobacco, mulberry, potato, broad bean and tomato have large leaf area and thin stratum corneum, and the nutrients in the solution are easy to be absorbed and often have better results; monocotyledons such as rice, barley, wheat, leek and other monocotyledons have small leaf area, the nutrients in the solution are difficult to be absorbed, and the spraying effect is relatively low; ② spraying site. It should be sprayed on the young leaves and functional leaves with strong metabolism. As the back of the leaf has more stomata than the front, the solution is easily absorbed, so it should be sprayed more; ③ spraying concentration. Different kinds of fertilizers have different spraying concentrations. Urea is 0.5% 0.1%, potassium nitrate is 0. 5%. 5% ④, 0.2% potassium dihydrogen phosphate, 0.5% potassium sulfate, 0.1% potassium sulfate, 0.2% potassium sulfate, 0.2% potassium phosphate, 0.2% potassium phosphate, 0.5% potassium sulfate, 0.2% potassium phosphate, 0.2% potassium dihydrogen phosphate, 0.5% potassium sulfate, 0.2% potassium sulfate, 0.2% potassium dihydrogen phosphate, 0.2% potassium dihydrogen phosphate, 0.5% potassium sulfate, 0.2% potassium sulfate, 0.2% potassium dihydrogen phosphate, 0.2% potassium dihydrogen phosphate, 0.5% potassium sulfate, 0.2% potassium sulfate, 0.2% potassium dihydrogen phosphate, 0.5% potassium sulfate, 0.2% potassium sulfate, 0.2% potassium dihydrogen phosphate, 0.5% potassium sulfate, 0.2% potassium sulfate. The absorption of nutrients by leaves depends on the residence time of fertilizer on the leaves. When the temperature is high at noon, the water in the solution is easy to evaporate, which is not conducive to the absorption of nutrients, and it is not suitable to apply when the dew is not dry. It is usually appropriate to spray after 3pm. The addition of 0.1%-0.2% detergent to the solution can reduce the surface tension of the solution and increase the retention time of the solution on the leaves, thereby increasing the amount of nutrient absorption.