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Foliar fertilizer spraying technology and issues that need attention

Date: 2024-06-01 14:16:26
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1. Foliar fertilizer spraying of vegetables should vary according to the vegetables
⑴ Leafy vegetables.
For example, cabbage, spinach, shepherd's purse, etc. require more nitrogen. Spraying fertilizer should be mainly urea and ammonium sulfate. The spraying concentration of urea should be 1~2%, and ammonium sulfate should be 1.5%. Spray 2~4 times per season, preferably in the early growth stage.

⑵ Melon and fruit vegetables.
For example, peppers, eggplants, tomatoes, beans and various melons have a relatively balanced need for nitrogen, phosphorus and potassium. A mixed solution of nitrogen, phosphorus and potassium or compound fertilizer should be used. Spray 1~2% urea and 0.3~0.4% potassium dihydrogen phosphate mixed solution or 2% compound fertilizer solution.

Generally, spray 1~2 times in the early and late growth stages. Spraying in the late stage can prevent premature aging, enhance stamina, and has a good yield-increasing effect.

⑶ Root and stem vegetables.
For example, garlic, onion, radish, potato and other plants need more phosphorus and potassium. Foliar fertilizer can be selected from 0.3% potassium dihydrogen phosphate solution and 10% wood ash extract. Generally, spray 3 to 4 times per season for better results.

2. Periods when foliar fertilizer is needed:

① When encountering pests and diseases, using foliar fertilizer is beneficial to improve the disease resistance of plants;
② When the soil is acidic, alkaline or salinity is too high, which is not conducive to the plant's absorption of nutrients;
③ Fruit-bearing period;
④ After the plant encounters air damage, heat damage or frost damage, choosing the right time to use foliar fertilizer is beneficial to alleviate the symptoms.

3. Periods when it is best not to use foliar fertilizer:

① Flowering period; flowers are delicate and susceptible to fertilizer damage;
② Seedling stage;
③ High temperature and strong light period during the day.

4. Variety selection should be targeted

At present, there are many varieties of foliar fertilizers sold on the market, mainly including nitrogen, phosphorus, potassium nutrient elements, trace elements, amino acids, humic acid, growth regulators and other types.
It is generally believed that: when the base fertilizer is insufficient, foliar fertilizers mainly containing nitrogen, phosphorus and potassium can be used; when the base fertilizer is sufficient, foliar fertilizers mainly containing trace elements can be used.

5. The solubility of foliar fertilizers should be good and they should be used as soon as they are prepared

Since foliar fertilizers are directly prepared into solutions for spraying, foliar fertilizers must be soluble in water. Otherwise, the insoluble substances in the foliar fertilizers will not only be absorbed after being sprayed on the surface of crops, but sometimes even cause damage to the leaves.
The physical and chemical properties of fertilizers determine that some nutrients are easy to deteriorate, so some foliar fertilizers should be used as soon as they are prepared and cannot be stored for a long time.

6. The acidity of foliar fertilizers should be appropriate
Nutrients have different existence states under different pH values. To maximize the benefits of fertilizers, there must be a suitable acidity range, generally requiring a pH value of 5-8. If the pH value is too high or too low, in addition to affecting the absorption of nutrients, it will also harm the plants.

7. The concentration of foliar fertilizer should be appropriate

Since foliar fertilizer is directly sprayed on the leaves of the aboveground part of crops, the buffering effect of plants on fertilizers is very small.

Therefore, it is important to master the concentration of foliar fertilizer spraying. If the concentration is too low, the amount of nutrients exposed to crops is small, and the effect is not obvious; if the concentration is too high, it will often burn the leaves and cause fertilizer damage.

The same foliar fertilizer has different spraying concentrations on different crops, which should be determined according to the type of crop.

8. The time for foliar fertilizer spraying should be appropriate

The effect of foliar fertilizer application is directly related to temperature, humidity, wind force, etc. It is best to choose a windless and cloudy day or a day with high humidity and low evaporation before 9 am for foliar spraying. It is best to spray after 4 pm. If it rains 3 to 4 hours after spraying, it is necessary to spray again.

9. Choose the appropriate spraying site

The leaves and stems of the upper, middle and lower parts of the plant have different metabolic activities, and their ability to absorb nutrients from the outside world varies greatly. It is necessary to choose the appropriate spraying site.

10. Spraying during the critical period of crop growth

Crops absorb and utilize fertilizers differently at different growth stages. In order to maximize the benefits of foliar fertilizers, the most critical period of spraying fertilizers should be selected according to the growth conditions of different crops to achieve the best effect.

For example, the root absorption capacity of gramineous crops such as wheat and rice weakens in the late growth period. Foliar fertilization can supplement nutrition and increase the number and weight of grains; spraying during the fruiting period of watermelon can reduce flower and fruit drop and increase the fruiting rate of watermelon.

11. Add additives

When spraying fertilizer solution on the leaves, add appropriate additives to increase the adhesion of fertilizer solution on plant leaves and promote fertilizer absorption.

12. Combine with soil fertilization

Because the roots have a larger and more complete absorption system than the leaves, it is determined that more than 10 foliar fertilizations are needed to achieve the total amount of nutrients absorbed by the roots for large amounts of nutrients such as nitrogen, phosphorus, and potassium. Therefore, foliar fertilization cannot completely replace root fertilization of crops and must be combined with root fertilization.

The amount of foliar fertilizer applied is small, the effect is rapid and obvious, and the utilization rate of fertilizer is improved. It is an economical and effective fertilization measure, especially the foliar application of some trace elements is more unique.

However, we should also see that foliar fertilization is more troublesome and labor-intensive. It is also easily affected by climatic conditions. Due to different crop types and growth periods, the effects of foliar fertilization vary greatly.
Therefore, it is necessary to correctly apply foliar fertilization technology on the basis of root fertilization to give full play to the role of foliar fertilizer in increasing production and income.
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