The Advantages of Foliar Fertilization and Practical Tips to Improve Its Effectiveness

Foliar fertilization allows nutrients to enter the plant through the leaves and take part in the crop's metabolism and the synthesis of organic matter. Compared with soil fertilization, it has the following five advantages: (1) Rapid absorption. When urea is sprayed on apple and pineapple leaves, 50% can be absorbed after 1 to 4 hours; when urea is sprayed on the leaves of cucumber, broad bean, tomato and banana, 50% can also be absorbed after 1 to 6 hours. In contrast, urea applied to the soil generally takes 3 to 5 days to show results; (2) High fertilizer use efficiency. According to research, the use efficiency of foliar-sprayed boron fertilizer is about 8 times that of applying it as a base fertilizer; (3) It can avoid the fixation of fertilizers such as phosphorus, iron and zinc in the soil; (4) When the crop root system is under environmental stress (such as salt damage, water damage, drought, etc.), or when the crop has special nutritional requirements at a certain stage, it can replenish nutrients in time; (5) It can improve the quality of agricultural products.

Although foliar topdressing has many advantages, it is limited by factors such as a relatively low suitable concentration range and a greater expenditure of labor. When the crop's fertilizer demand is large, soil fertilization is still needed to supply nutrients so as to meet the crop's nutrient requirements throughout the entire growth period. Therefore, foliar fertilization can only be an auxiliary fertilization measure.

Appendix: How to improve the effect of foliar fertilization?

The effect of foliar fertilization is related to factors such as the crop species sprayed, the spraying site, the spraying concentration and the spraying time. (1) Crop species sprayed. The leaves of dicotyledonous plants such as cotton, tobacco, mulberry, potato, broad bean and tomato are large in area and thin in cuticle, so nutrients in the solution are easily absorbed, and the results are often relatively good; the leaves of monocotyledonous plants such as rice, barley, wheat and Chinese chives are small in area, so nutrients in the solution are harder to absorb, and their spraying effect is relatively lower; (2) Spraying site. It should be sprayed on vigorously metabolizing young leaves and functional leaves. Because the underside of the leaf has more stomata than the upper side and the solution is more easily absorbed, more should be sprayed there; (3) Spraying concentration. Different types of fertilizer have different spraying concentrations. Urea is 0.5% to 1%, potassium nitrate is 0.5% to 1%, monopotassium phosphate is 0.2% to 0.5%, potassium sulfate is 0.5% to 2%, and trace elements are usually around 0.1% to 0.2%; (4) Spraying time. The absorption of nutrients by leaves depends on how long the fertilizer remains on the leaves. At noon, when the temperature is relatively high, the water in the solution evaporates easily, which is not conducive to nutrient absorption; when the dew has not yet dried, it is also not suitable to apply. It is usually best to spray after 3 p.m. Adding 0.1% to 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 nutrients absorbed.