What are the precautions for spraying foliar fertilizer on soybeans?
Foliar fertilization of soybeans has the advantages of small dosage, quick results, high fertilizer efficiency and good effect, and has been widely promoted and applied in recent years. However, because some farmers mistakenly believe that foliar fertilization is "beneficial and harmless, the more the better," in actual practice there are problems such as randomly choosing the type of fertilizer, randomly increasing the dosage, randomly...
Foliar fertilization of soybeans has the advantages of small dosage, quick results, high fertilizer efficiency and good effect, and has been widely promoted and applied in recent years. However, because some farmers mistakenly believe that foliar fertilization is "beneficial and harmless, the more the better," in actual practice there are problems such as randomly choosing the type of fertilizer, randomly increasing the dosage, randomly determining the spraying time, and randomly increasing the number of applications, which not only affects the effect of foliar fertilization but sometimes even causes varying degrees of damage to the plants. Therefore, when carrying out foliar fertilization on soybeans, the following points should be noted:
(1) Type of fertilizer. Fertilizer should be applied according to the condition of the seedlings: if the plants grow slowly, are thin and weak, short and small, with yellowing leaves, this indicates nitrogen deficiency, and foliar fertilization should be mainly nitrogen with a small amount of phosphorus and potassium fertilizer; conversely, if the plants are tall, tender green, with long internodes, and nitrogen nutrition is sufficient, foliar fertilization should be changed to mainly phosphorus and potassium, and cannot remain fixed and unchanging.
(2) Fertilizer solution concentration. Different crops, at different times, have very different tolerances to different fertilizers. If the fertilizer solution concentration is too high, it often causes fertilizer burn to the leaves. Especially when foliar fertilization is carried out at higher temperatures, within the appropriate concentration range, the principle of "choose the lower end rather than the higher end" should be followed. In addition, at the seedling stage of plants, the leaf tissue is tender, so the concentration of the sprayed fertilizer should be appropriately lower; when deficiency symptoms appear, the concentration should be appropriately higher; the concentration for spraying trace element fertilizers should be lower, and the concentration for spraying common element fertilizers can be appropriately higher. For different foliar fertilizers, the spraying concentrations are generally: urea 0.5%-2.0%, superphosphate 1%-5%, monopotassium phosphate 0.2%-0.5%, boric acid 0.1%-0.5%, ammonium molybdate 0.02%-0.05%, zinc sulfate 0.05%-0.2%.
(3) Spraying time. In terms of the fertilization stage, it should generally be carried out during the middle and late stages of growth and development when the leaf area is relatively large, for the best effect. Spraying fertilizer when the plant leaf area is relatively small not only wastes a lot of fertilizer solution but also gives less than ideal results. Molybdenum fertilizer should be sprayed before soybean flowering, while boron fertilizer and zinc fertilizer are best sprayed at the early flowering stage of soybeans. In terms of the time of day for spraying, it should be done on a windless cloudy day or in the morning on a sunny day after the dew on the leaf surface has dried, avoiding the period of strong sunlight and high temperature, and spraying in the morning and evening. If there are water droplets or dewdrops on the leaves when spraying, it will reduce the concentration of the fertilizer solution and fail to achieve the fertilization effect. If spraying is done under strong sunlight and high temperature, the air humidity is low, which not only causes more volatilization and waste of the fertilizer solution, but the fertilizer solution also dries quickly after spraying, making it difficult for the leaves to absorb, which reduces fertilizer utilization efficiency, and sometimes because the water in the fertilizer solution on the leaves evaporates too quickly, the concentration rises rapidly and causes "leaf burn."
(4) Number of sprayings. Many farmers believe that the more times foliar fertilization is applied, the better. In fact, generally 2-3 sprayings are sufficient, and each spraying should generally be spaced more than 7-10 days apart. For trace element fertilizers, the number of sprayings should not be too many and the concentration should not be too high, otherwise it will not only fail to increase yield but will instead cause trace element poisoning.
In addition to considering the above four factors, three more points should be noted: first, although the amount of foliar fertilizer is small, it must be fully dissolved and stirred evenly before spraying; second, the underside of plant leaves has less cuticle and more stomata, making it easier to absorb, so foliar fertilization should focus mainly on the underside of the leaves, with the upper surface as a supplement; third, some foliar fertilizers can be mixed with fertilizers or pesticides, but many cannot be mixed arbitrarily, otherwise it will affect fertilizer efficiency and pesticide efficacy, and sometimes even cause damage to plants.
Our company produces four types of foliar fertilizer: compound foliar fertilizer uses agricultural ammonium molybdate as the main raw material and is rich in nitrogen, phosphorus, potassium, calcium, magnesium, iron, boron, zinc, copper, ammonium polyphosphate and other trace elements. It is mainly suitable for crops such as soybeans, wheat, rice and corn. Spray 60g or 300ml of liquid per mu, using 25-30kg of water, to make crops grow luxuriantly, with thick and rich leaves and plump grains, and it can increase yield by more than 20%.
Nutritional foliar fertilizer: mainly suitable for vegetables and melons and fruits. This type of foliar fertilizer has relatively high contents of nutrients such as nitrogen, phosphorus, potassium, molybdenum and more than ten kinds of trace elements. Its main function is to provide various nutrient elements to crops, improve the nutritional status of crops, and is especially suitable for supplementing various nutrients in the late stage of crop growth.
Plant-based foliar fertilizer is mainly suitable for tea leaves, tobacco leaves, flowers and fruit trees. This type of foliar fertilizer contains substances that regulate plant growth, such as auxin, ammonium polyphosphate, calcium, magnesium, molybdenum, iron, boron and other components. Its main function is to regulate the growth and development of crops, making crop leaves thick and rich, and it is suitable for use in the early and middle stages of plant growth.
Biological foliar fertilizer: this type of foliar fertilizer contains microorganisms and metabolites, such as amino acids, nucleotides and nucleic acid substances. Its main function is to stimulate crop growth, promote crop metabolism, and reduce and prevent the occurrence of pests and diseases.