Foliar nutrients are applied to crop the blade surface, the blade by absorbing a fertilizer type and play basic function, two upper and lower leaves of the plant epidermis, the epidermal cells, epidermal cells on the outer horny layer of wax and It can protect the mesophyll cells under the epidermis tissue from functions such as photosynthesis and respiration, and is not affected by changes in external adverse conditions. The leaf shows many tiny pores and exercises the function of gas replacement. Studies have shown that the stratum corneum long carbon chain fatty acid from a composition having a hydroxyl group and a carboxyl group, a hydroxyl group, a carboxyl group on a molecule a hydrophilic group and a gap of this polymer molecules can penetrate into the inner blade so that an aqueous solution, of course, The stomata on the surface of the blade is a more convenient passage for the foliar fertilizer to enter the blade. Urea substances in chemical fertilizers have a softening effect on the stratum corneum of epidermal cells, which can accelerate the infiltration of other nutrients. Therefore, urea substances have a softening effect on the stratum corneum of epidermal cells, which can accelerate the infiltration of other nutrients, so urea becomes leaf surface. An important component of fat.
First, the type of foliar fertilizer
At present, there are many kinds of foliar fertilizers, and there are hundreds of species and even thousands of species in the country. According to its function and function, foliar fertilizer can be summarized into the following four categories:
1. Nutrient foliar fertilizer: The nutrient content of nitrogen, phosphorus, potassium and trace elements in such foliar fertilizer is high. The main function is to provide various nutrients for crops and improve the nutritional status of crops, especially suitable for crops. Supplementation of various nutrients in the late growth stage.
2 , regulating foliar fertilizer: This type of foliar fertilizer contains substances that regulate plant growth, such as auxin, hormones and other components, the main function is to regulate the growth and development of crops. Suitable for pre- and post-plant growth.
3 , bio-foliar fertilizer: This type of fertilizer contains microorganisms and metabolites, such as amino acids, nucleotides, nucleic acids. The main function is to stimulate crop growth, promote crop metabolism, reduce and prevent the occurrence of pests and diseases.
4 , composite foliar fertilizer: This type of foliar fertilizer is a wide variety, complex mixed forms. There are many functions, and a foliar fertilizer can provide nutrition and stimulate growth and regulation.
Second, the benefits of spraying foliar fertilizer on crops
1. Insufficient supplementation of root fertilization
When the crop is inconvenient for root fertilization, such as the late stage of crop growth, root activity declines, and the ability to absorb fertilizer decreases; or when the soil environment is unfavorable to crop growth, such as excessive water, drought, soil acidity, and alkali, causing crop roots. Absorption is blocked, and crops need to resume growth quickly. If the root application method can not meet the crop needs in time, only foliar application can be used to quickly supplement nutrients and meet the needs of crop growth and development.
2 , quickly add nutrition
In the process of crop growth, crops have shown some nutrient deficiencies, because the use of soil fertilization requires a certain amount of nutrients to be absorbed by the crops, and can not alleviate the symptoms of crop deficiency in time. At this time, using foliar fertilization, nutrients can quickly enter the plant through the leaves, solving the problem of deficiency.
3 , give full play to fertilizer efficiency
Certain fertilizers such as phosphorus, iron, manganese, copper, Zn, etc., if applied as a root, soil is easily fixed, influence the effect of the administration, while the use of foliar application will not be limited by the soil conditions. For example, some fruit trees and other deep root crops absorb less nutrients. If traditional fertilization methods are difficult to apply to the root absorption site, they can not fully exert their fertilizer efficiency, while foliar spray can achieve better results. effect.
4 , reduce pollution of the soil
The application of nitrogen fertilizer to the soil is likely to cause the accumulation of nitrate in groundwater and vegetables, which is harmful to human health. About 75% of the nitrates absorbed by humans come from vegetables. If foliar fertilization is adopted, appropriately reducing the amount of soil fertilization can reduce the nitrate content in plants and residual mineral nitrogen in the soil. In salinized soil, soil fertilization may increase the concentration of soil solution and increase the salinization of the soil. The use of foliar fertilization measures not only saves the amount of fertilization, but also reduces the pollution of soil and water sources. It is an effective fertilization technique with two advantages.
5 , economical and cost-effective
Various kinds of trace elements in the growth and development of crop nutrients essential, but small amounts administered, e.g. molybdenum fertilizer, the amount of only tens of grams per acre, if the method is not easy to Exogenous applied uniformly. Only by taking foliar application in order to reach the cost-effective. According to research estimates, the general crop sprays boron fertilizer on the foliar surface, and the utilization rate of boron is 8.18 times that of the base application . From the perspective of economic efficiency, foliar application is more cost-effective than roots.
Third, the foliar fertilizer in the application process
1. Vegetable foliar fertilizer should vary from dish to vegetable.
(1) Leafy vegetables. For example, cabbage, spinach, and leek need more nitrogen. Spray fertilizer should be mainly urea and ammonium sulfate. The concentration of urea should be 1~2% , ammonium sulfate is 1.5% , and sprayed 2~4 times per season . Spraying in the early stage of growth is preferred.
(2) Fruits and vegetables. Such as pepper, eggplant, tomato, beans and various melons, the need for NPK is relatively balanced, should use NPK mixed solution or compound fertilizer. Spray 1~2% urea with 0.3~0.4% potassium dihydrogen phosphate or 2% compound fertilizer solution. It is usually sprayed 1 or 2 times in the early and late stages of growth . Spraying in the later stage can prevent premature aging, enhance stamina, and have a good yield increase effect.
(3) Root vegetables. For example, garlic, onion, radish, potato, etc. require more phosphorus and potassium, and foliar fertilizer can use 0.3% potassium dihydrogen phosphate solution and 10% grass ash leaching solution. Generally, it is sprayed 3~4 times per season , and the effect is better.
2. Select the appropriate spray concentration. Foliar fertilization concentration is directly related to the effect of spraying. If the concentration of the solution is too high, the crop leaves are easily burned after spraying; the solution concentration is too low, which not only increases the workload, but also fails to meet the nutritional requirements of supplementary crops. Therefore, in the application, it should be formulated according to the local conditions due to different fertilizers and crops. 　　
3. Select the appropriate spray method. The preparation solution should be uniform, the spray mist should be evenly distributed, and the number of sprays needs to be seen. 　　
4 , master the spraying period. The period of foliar fertilization should be based on the demand for nutrients in different growth stages of various crops, and the selection of crop nutrient elements should be carried out at the most and most urgently to achieve the best results. 　　
5. Select the appropriate spraying time. The quality and temperature, humidity, wind, etc. are directly related to the effect of foliar fertilization of spraying is preferably performed under no wind cloudy or humidity, 9:00 am before a small amount of evaporation, is appropriate in most After 4 pm, if it rains 3 to 4 hours after spraying , it needs to be refilled. 　　
6. Select the appropriate spraying site. The upper and middle leaves and stems of the plant have different metabolic dysfunctions, and the ability to absorb nutrients from the outside is quite different. It is necessary to select appropriate spraying sites. 　
7. Add additives. When spraying the fertilizer on the foliar surface, appropriate additives are added to improve the adhesion of the fertilizer solution on the leaves of the plant and promote the absorption of the fertilizer. 　　
8. Combine with soil fertilization. Because the root has a larger and more complete absorption system than the leaf, for large amounts of nutrients such as nitrogen, phosphorus, potassium, etc., it is determined that more than 10 foliar fertilization can reach the total amount of nutrients absorbed by the root. Therefore, foliar fertilization cannot completely replace the root fertilization of crops and must be combined with root fertilization. 　　
Leaf leaven administered less, the effect of rapid significantly improve the utilization of fertilizers. It is a kind of fertilization measure with good economy and good effect, especially the application of some trace elements to the foliage is more unique. However, we should also see that foliar fertilization is more cumbersome and requires more labor. It is also susceptible to climatic conditions. Because of different crop types and growth periods, foliar fertilization effects vary widely. Therefore, must be based on the roots of fertilization on the correct application of foliar fertilization techniques, in order to give full play to increase production, income effect of foliar fertilizer.
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