Foliar fertilizer and foliar fertilization
In addition to absorbing nutrients through the root system, the crop can also absorb nutrients. Foliar fertilization is also called extra-root fertilizer or foliar spray fertilizer. This fertilization is a fertilization method often used in production. Its outstanding features are strong pertinence, fast absorption of nutrients, avoiding the fixed effect of soil on certain nutrients, improving nutrient utilization, and low fertilization, which are suitable for the application of trace fertilizers, and have significant yield increase effects, especially in the soil environment. Insufficient moisture, excessive moisture or drought and low humidity conditions, soil acidity and alkali and other factors cause root absorption to be blocked, or crop nutrients need nutrient replenishment, and the ability of the root system to absorb water in the late growth stage of crops. Can achieve better yield increase. First, the types of foliar fertilizers There are a wide variety of foliar fertilizers. There are hundreds of varieties, and there are about hundreds or even thousands of species in the country. Foliar fertilizer can be summarized into the following four categories according to its function and function. In the first category, nutrient-type foliar fertilizers have high nutrient content such as nitrogen, phosphorus, potassium, and trace elements in such foliar fertilizers. The main function is to provide various nutrient elements for crops and improve the nutritional status of crops, especially suitable for Various nutritional supplements at the end of crop growth. The second category: Regulated foliar fertilizers These foliar fertilizers contain substances that regulate plant growth, such as auxin and hormones. Their main function is to regulate crop growth and development. Suitable for early and mid-plant growth. The third category: Bio-foliar fertilizer This type 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 pests and diseases. The fourth category: Compound foliar fertilizers There are various kinds of foliar fertilizers, and the compound mixing forms are various. There are many kinds of its functions. A kind of foliar fertilizer can provide nutrition, and it can stimulate the development of growth regulation. Second, foliar fertilizer technology The effect of foliar fertilizer application is often constrained and affected by many factors, in order to improve the effect of foliar fertilizer should adopt scientific fertilization methods and the correct fertilization techniques. (1) Choosing the right variety of fertilizer According to the growth and development of the crop and the nutritional status, select suitable varieties of foliar fertilizer. In the early stage of crop growth, to adjust the growth and development of the selection of foliar fertilizer, if the crop lack of nutrients or root growth in the late growth period, the selection of nutrient foliar fertilizer. Fertilizer varieties commonly used for foliar spraying in production mainly include urea, potassium dihydrogen phosphate, superphosphate, potassium sulfate, and various trace element fertilizers, and suitable fertilizer varieties can be selected according to specific conditions. (2) The concentration of spraying shall be appropriate. Within a certain concentration range, the speed and quantity of nutrients into the leaves will increase with the increase of the concentration of the solution. However, if the concentration is too high, it will be prone to fertilizer damage, especially for trace element fertilizers. The critical range between excesses is very narrow and should be strictly controlled. There are also foliar fertilizers containing growth regulators, which should be sprayed in strict accordance with the concentration requirements in order to prevent improper regulation. Different crops have different concentrations of different fertilizers. Taking urea as an example, suitable concentrations are 1.5%-2% for rice, wheat and other gramineous crops, 1%-1.5% for radish, cabbage, cabbage, and cucumber, and 0.5% for potatoes, watermelons, and eggplants. 0.8%, apple, pear, grape, tea on the concentration of 0.5%, onion, tomato, greenhouse cucumber concentration of 0.2% -0.3%. (C) The spraying time should be appropriate for the amount of nutrients the leaves absorb during nutrient application and the length of time the solution wets the leaves. The longer the moisturizing time, the more nutrients the leaves absorb and the better the effect. In general, it is appropriate to keep the wet time of the leaf at 30-60 minutes. Therefore, the best application of foliar fertilizer is in windy weather in the evening. Spraying fertilizer in the morning with dew will reduce the concentration of the solution and affect the effect of fertilization. Before the rain or the rain can not be foliar dressing, because the nutrients easily lost, do not achieve their intended effect, if the rain after 3 hours after spraying, when the spray to be a sunny day, but the concentration should be reduced properly. (4) Spraying should be uniform, detailed, and thoughtful. Fertilizer requirements require small droplets and even spraying. Special attention should be paid to the growth of the upper leaves and the back of the leaves, because the new leaves absorb nutrients more than the old leaves and the back of the leaves. The speed is fast, absorption ability is strong. Especially for fruit trees such as peaches, pears, persimmons, apples, etc., the front of the cuticle of the leaves is 3-4 times thicker than the back, and more attention should be paid to the back of the spraying blades to facilitate absorption. Therefore, when the leaves are fertilized, the front and back sides of the leaves must be sprayed as carefully as possible. (5) The number of sprays should not be too few, and the concentration of top-dressing crops with separated crops is generally low, and the amount of each time is very small, which is much lower than the demand for crops. Therefore, the frequency of foliar application should generally not be less than 2-3 times. As for the nutrients (such as iron, boron, calcium, phosphorus, etc.) that have little or no mobility in the crop, more attention should be paid to increasing the number of sprays. When sprayed with foliar fertilizer containing regulators, attention should be paid to spraying intervals, the interval should be at least one week or more, the number of spraying should not be too much, to prevent improper regulation, resulting in harm. (6) When foliar fertilizers are used to mix foliar fertilizers, the use of two or more foliar fertilizers can be used in a rational mix, which can save time and labor, and the effect of yield increase will be even more pronounced. However, after the fertilizers are mixed, they must have no adverse reactions or do not reduce the fertilizer efficiency, otherwise they cannot achieve the purpose of mixing. In addition, when the fertilizer is mixed, it is necessary to pay attention to the concentration and the pH of the solution. Under normal conditions, the pH value of the solution is about 7 in the neutral condition to facilitate the absorption of the leaves. (7) Add moisturizer to the fertilizer solution The crop leaves have a layer of thick and thin cuticles. The solution penetration is difficult. For this reason, appropriate amount of wetting agent such as neutral soap can be added to the leaf fertilizer solution. A good detergent, etc., to reduce the surface tension of the solution, increase the contact area with the blade, and improve the effect of foliar dressing. In the purchase of foliar fertilizer, the type and function of the foliar fertilizer indicated in the packaging should be noted so that the purpose of foliar fertilization is consistent with the function of foliar fertilizer; also pay attention to whether the product has a foliar fertilizer registration certificate issued by the Ministry of Agriculture. No. and product standard certification number to ensure the quality and efficacy of foliar fertilizer.