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First, the symptomatic fertilizer The composition of the spray solution depends on the purpose of spraying fertilizer. Foliar fertilizer should be selected first according to the type of crop and its symptoms. If it is to promote early development or increase 1000-grain weight in the later stage, it can spray nitrogen fertilizer and phosphate fertilizer; in order to increase leaf area and promote vegetative growth, nitrogen and potassium fertilizers can be selected: for the prevention and treatment of diseases caused by lack of trace elements, micro-fertilizer can be sprayed.
Second, the correct adjustment of the pH of the spray solution (ie pH) Adjust the pH of the spray solution, can improve the effect of spraying, generally according to the composition and purpose of the spray solution to adjust. If the purpose of spraying is to provide cationic nutrients (such as NH4+, K+, Mg2+, etc.) to the crop, the solution should be adjusted to slightly alkaline. Under slightly alkaline conditions, these cations are easily absorbed by the leaves of the plant; The purpose is to provide anion nutrients (such as NO3-, H2PO4-, etc.), the solution should be adjusted to slightly acidic, which is beneficial to plants to absorb anions. In addition, different types of foliar fertilizer, foliar fertilizer and pesticides must be mixed, attention must be paid to the acid-base properties between them, to avoid adverse chemical reactions due to improper matching, resulting in condensation, sedimentation, flocculation, etc., so that fertilizer efficiency is reduced, Even the crops are harmful, and the correct combination can achieve cost-effective and multi-functional effects.
3. Extend the wetting time of the spray solution on the leaves. The sprayed foliar fertilizer can only be fully absorbed by the plants under wet conditions. The greater the adhesion of the spray solution on the leaf surface, the higher the leaf surface absorption rate. The wetting time is generally required to be more than 1 hour. In order to meet this requirement, it is most suitable to spray in the evening without wind. A small amount of wetting agent may also be added to the spray solution to reduce the surface tension of the solution and increase the degree of expansion of the solution on the blade. The humectant may be a neutral soap or a surfactant, and the concentration is preferably 0.1-0.2%.
Fourth, the spraying method should be appropriate The minerality of various mineral nutrients in the plant is different, so there should be a difference in the number and location of spraying. Generally, the foliar fertilizer of mineral nutrients is sprayed with 4O-60kg of fertilizer solution every 667 square meters. It needs to be sprayed 2-3 times, each time 10-15d, and some trace elements with poor mobility are Appropriately increase the number of spraying, and pay attention to the effect of spraying on new leaves, such as iron supplementation, the effect of chelating EDTA?Fe is better than inorganic ferrous sulfate. Foliar spray fertilizer should be carried out when the air temperature is high. It is not suitable for spraying in dry and hot weather. If it is raining 24 hours after spraying, it needs to be re-sprayed.
V. The concentration of the solution should be suitable. The test and production practice prove that the concentration and method of the commonly used foliar fertilizer solution are: 1. Urea: common concentration 1% -2%; 2. Diammonium phosphate: commonly used concentration of 1% -5%; 3. Superphosphate: Commonly used concentration 2%-4%; 4. Potassium dihydrogen phosphate: commonly used concentration 0.2%-0.3%. Urea and potassium dihydrogen phosphate can be used as needed. The diammonium phosphate and the superphosphate should be immersed in a small amount of water for 24 hours, then filtered out and the water is sprayed; Mixing nitrogen and phosphorus: After taking 1000g of superphosphate and adding a little water for 24 hours, filter out the clear liquid and add 50kg of water, then add 500-1000g of urea and mix evenly and spray it; 6. Potassium chloride or potassium sulfate is usually used at a concentration of 1% to 1.5%; Grass ash: commonly used concentration 5%??7%, soaked with hay wood ash and water for 15 hours, fully stirred and allowed to stand for 1? 2 hours to take the clear liquid spray. Tobacco, potato, grape, etc. avoid chlorine crops, it is not appropriate to spray potassium chloride; Zinc sulfate: common concentration 0.1%-0.2%; Borax (or boric acid): Commonly used concentrations of 0.2% to 0.3%. When preparing the solution, first add a small amount of 45 ° C hot water to fully dissolve, and then add enough water to spray; Ammonium molybdate: common concentration 0.05% -0.1%; Manganese sulfate: common concentration 0.05%-0.1%; 12. Ferrous Sulfate: Sprayed with a 0.05%-0.3% solution. Due to the poor fluidity of iron, it should be sprayed several times to be uniform; Copper sulfate: commonly used concentration of 0.01% - 0.02%. When spraying, a small amount of lime solution may be added to the solution to reduce the concentration of sulfuric acid in the solution; Increasing the production of bacteria: 15 to 30 ml of crops are sprayed with 40-50 kg of water, and fruit trees are sprayed with 80 to 100 ml of water for 150 kg; Sodium humate: commonly used concentration of 0.06% -0.1% spray; Rice vinegar: commonly used concentration of 200-250ml for water 40-50kg.
Problems in improving the spraying effect of crop foliar fertilizer
Crop foliar fertilizer has the advantages of less fertilizer, high utilization efficiency, quick effect, etc. It is an effective method to supplement nutrition and prevent crop deficiency. It is important to solve the problem of de-fertilization in the late stage of crop growth, increase the 1000-grain weight and promote the rapid recovery of crops after natural disasters. However, the physical and chemical properties of various types of foliar fertilizers are different. The following points must be noted when spraying:
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