Types of foliar fertilizer and matters needing attention in spraying

Foliar fertilizer is a type of fertilizer in which nutrient elements are applied to the surface of crop leaves and play a basic function through the absorption of leaves. Plant leaves have upper and lower layers of epidermis, which are composed of epidermis cells. The outer side of the upper epidermis cells has horny layer and wax, which can protect the mesophyll cells under the epidermis from photosynthesis and respiration, and are not affected by the changes of external adverse conditions. The blade also has many tiny pores, which exercise the function of gas replacement. The study shows that the stratum corneum is composed of a long carbon chain fatty acid polymer with hydroxyl and carboxyl groups. The molecular gap of this polymer and the hydrophilic groups of hydroxyl and carboxyl groups on the molecule can let the aqueous solution permeate into the leaf. The stomata on the leaf surface are more convenient channels for foliar fertilizer to enter the leaves. Urea in chemical fertilizer can soften the cuticle of epidermis and accelerate the infiltration of other nutrients, so urea can soften the cuticle of epidermis and accelerate the infiltration of other nutrients. therefore, urea has become an important component of foliar fertilizer. 1. Types of foliar fertilizer at present, there are many kinds of foliar fertilizer, and there are hundreds or even thousands of them all over the country. According to its function and function, foliar fertilizer can be summarized into the following four categories: 1. Nutritional foliar fertilizer: this kind of foliar fertilizer has high contents of nitrogen, phosphorus, potassium and trace elements, and its main function is to provide various nutrient elements for crops. improve the nutritional status of crops, especially suitable for the supplement of various nutrients in the later stage of crop growth. 2. Regulated foliar fertilizer: this kind of foliar fertilizer contains substances that regulate plant growth, such as auxin, hormones and so on. Its main function is to regulate the growth and development of crops. It is suitable for use in the early and middle stages of plant growth. 3. Biological foliar fertilizer: this kind of fertilizer contains microorganisms and metabolites, such as amino acids, nucleotides and nucleic acids. The main function is to stimulate crop growth, promote crop metabolism, reduce and prevent the occurrence of diseases and insect pests. 4. Compound foliar fertilizer: there are many kinds of foliar fertilizer and various forms of compound mixed fertilizer. It has a variety of functions, a foliar fertilizer can not only provide nutrition, but also stimulate growth and regulate development. 2. the benefits of spraying foliar fertilizer on crops 1. Supplement the deficiency of root fertilization when it is inconvenient for crops to apply fertilizer at the root, such as in the later stage of crop growth, the root activity declines and the fertilizer absorption capacity decreases. Or when the soil environment is disadvantageous to crop growth, such as too much water, drought, soil over-acid and over-alkali, crop root absorption is blocked, and crops need to resume growth quickly. if root application method can not meet the needs of crops in time, only foliar spraying can quickly supplement nutrition and meet the needs of crop growth and development. 2. Rapid replenishment of nutrition in the process of crop growth, crops have shown some nutrient deficiency. Because it takes a certain amount of time for soil fertilization to be absorbed by crops, the symptoms of nutrient deficiency can not be alleviated in time. At this time, the use of foliar fertilization can quickly make nutrients enter the plant through the leaves and solve the problem of element deficiency. 3. Give full play to the effect of some fertilizers, such as phosphorus, iron, manganese, copper, zinc, etc., if root application, it is easy to be fixed by the soil, affecting the application effect, but foliar spraying will not be limited by soil conditions. For example, some fruit trees and other deep root crops absorb less nutrient elements, if the traditional fertilization method is difficult to apply to the root absorption site, and can not give full play to its fertilizer effect, while foliar spraying can achieve better results. 4. Reduce the pollution of the soil and apply a large amount of nitrogen fertilizer to the soil, which is easy to cause the accumulation of nitrate in groundwater and vegetables, and do harm to human health. About 75% of the nitrate absorbed by human beings comes from vegetables. If foliar fertilization is adopted and the amount of soil fertilizer is reduced appropriately, the content of nitrate in plants and the residual mineral nitrogen in the soil can be reduced. In salinized soil, soil fertilization may increase the concentration of soil solution and aggravate soil salinization. Foliar fertilization can not only save the amount of fertilizer application, but also reduce the pollution of soil and water source, which is an effective fertilization technology to kill two birds with one stone. 5. All kinds of trace elements are indispensable nutrients in the process of crop growth and development, but the application amount is very small, such as molybdenum fertilizer, which is only tens of grams per mu, but it is not easy to apply evenly by root application method. Only by foliar spraying can it be economical and effective. According to the study, when boron fertilizer is sprayed on the leaves of general crops, the utilization rate of boron is 8.18 times higher than that of basal application. In terms of economic benefits, foliar spraying is more cost-effective than root spraying. Matters needing attention in the process of foliar fertilizer application: 1. Spraying foliar fertilizer on vegetables should vary from vegetable to vegetable. ⑴ leafy vegetables. Such as cabbage, spinach, shepherd's purse and so on need more nitrogen, spraying fertilizer should be mainly urea, ammonium sulfate, the concentration of urea should be 1: 2%, ammonium sulfate should be 1.5%, spraying 2 times 4 times per season, it is appropriate to spray in the early stage of growth. ⑵ melons and fruits vegetables. Such as pepper, eggplant, tomato, beans and all kinds of melons, the need for nitrogen, phosphorus and potassium is more balanced, nitrogen, phosphorus and potassium mixed solution or compound fertilizer should be selected. Spray a mixture of 1% urea and 0.3% 0.4% potassium dihydrogen phosphate or 2% compound fertilizer solution. Generally, it was sprayed 1 and 2 times in the early and later stages of growth. Spraying in the later stage can prevent premature senescence, enhance stamina, and has a good effect on increasing production. ⑶ rhizome vegetables. Such as garlic, onion, radish, potato and so on need more phosphorus and potassium, foliar fertilizer can choose 0.3% potassium dihydrogen phosphate solution, 10% plant ash leaching solution. It is generally sprayed 3 times 4 times per season, and the effect is better. 2. Choose the appropriate spraying concentration. Foliar fertilization concentration is directly related to the effect of spraying, if the solution concentration is too high, it is easy to burn crop leaves after spraying; too low solution concentration not only increases the workload, but also can not meet the requirements of supplementary crop nutrition. Therefore, in the application, it should be prepared according to local conditions because of fertilizer and different crops. 3. Choose the appropriate spraying method. The preparation of the solution should be uniform, the spray point should be even and fine, and the spraying times should be needed. 4. Master the spraying period. In the period of foliar fertilization, according to the demand for nutrient elements in different growth and development stages of various crops, we should choose the most urgent and most urgent time to spray crop nutrient elements in order to achieve the best effect. 5. Choose the appropriate spraying time. The effect of foliar fertilization is directly related to temperature, humidity and wind. Foliar spraying is best chosen before 9: 00 in the morning when there is no wind or cloudy days with high humidity and low evaporation, and the most suitable one is after 4: 00 p. M. if it rains 3-4 hours after spraying, supplementary spraying is needed. 6. Select the appropriate spraying site. Due to the different metabolic activity of the upper, middle and lower leaves and stems of the plant, the ability of absorbing nutrients to the outside world is quite different, so the appropriate spraying site should be selected. 7. add auxiliaries. When spraying fertilizer solution on the leaf surface, proper auxiliaries should be added to improve the adhesion of fertilizer solution on plant leaves and promote the absorption of fertilizer. 8. Combine with soil fertilization. Because the root has a larger and more perfect absorption system than the leaf, it takes more than 10 times of foliar fertilization to reach the total amount of nutrients absorbed by the root for a large amount of nutrient elements such as nitrogen, phosphorus, potassium and so on. Therefore, foliar fertilization can not completely replace the root fertilization of crops, and must be combined with root fertilization. The application amount of foliar fertilizer 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 troublesome and costs a lot of labour. at the same time, it is easily affected by climatic conditions, and the effect of foliar fertilization varies greatly due to different crop types and growth periods. Therefore, foliar fertilization technology must be correctly applied on the basis of root fertilization in order to give full play to the role of foliar fertilizer in increasing yield and income.