1.化肥在化肥中的概念，含有两种或更多种主要营养素如N，P，K等的肥料称为复合肥料。含有两个主要营养素的复合肥称为二元复合肥料，含有三种主要营养素的一种称为三元化合物肥料，含有超过三种营养素的营养素称为复合肥料。复合肥料用于表达它们的组合物，其具有相应的N-P2O5-k2O百分比。如果某种复合肥含有10％N，520％P 2 O和10％K 2 O，则化合物肥料表示为10-20-10。在K2O内容数之后，一些也标有S，例如12-24-12（s），这意味着它包含K2SO4。根据其制造过程，复合肥可分为三类：复合肥，复合肥和复合肥料。化合物肥料是通过化学方法制备的复合肥料，例如磷酸二氢钾。复合肥是含有多种元素的复合肥，通过某些加工技术通过肥料制造商的两种或更多种元素肥料重新造粒。在加工过程中发生部分化学反应，其通常称为复合肥料。复合肥是指这种复合肥料。 Mixed compound fertilizer is a compound fertilizer made by mechanically mixing several fertilizers. During the processing, it is simply mechanically mixed without chemical reaction. For example, ammonium chloride is a mixture of ammonium chloride and ammonium phosphate. 2. Characteristics of compound fertilizer The advantages of compound fertilizers are: high effective components, various nutrient types, few side components, and small adverse effects on the soil; low production cost; good physical properties. Disadvantages of compound fertilizers: the nutrient ratio is fixed, and it is difficult to adapt to the different needs of various soils and various crops. It is often necessary to supplement and adjust with simple fertilizers. It is difficult to meet the requirements of fertilization technology. The movement laws of various nutrients in the soil and the requirements for fertilization technology are different. For example, nitrogen fertilizer has high mobility, P and K fertilizers have small mobility, but the aftereffects of phosphorus and potassium fertilizers are long. In the application, nitrogen fertilizer is usually used as topdressing, and phosphorus and potassium fertilizer are usually used as base fertilizer and seed fertilizer. Compound fertilizer is to apply various nutrients in the same place and at the same period. In this way, it is difficult to meet the nutrient requirements of a certain period of crops. Therefore, it is necessary to find out the local soil conditions, the growth characteristics of various crops, and the law of fertilizer requirements, and apply appropriate compound fertilizers. 3. The main types, properties and application of compound fertilizers (1) Ammonium phosphate is abbreviated as ammonium phosphate, which is made by neutralizing phosphoric acid with ammonia. Due to the different degree of neutralization of ammonia, monoammonium phosphate, diammonium phosphate and triammonium phosphate can be produced respectively. The current domestic ammonium phosphate is actually a mixture of monoammonium phosphate and diammonium phosphate. Containing N14%-18%, P2O546%-50%, pure ammonium phosphate is off-white, dark gray due to impurities. Ammonium phosphate is easily soluble in water and has a certain degree of hygroscopicity. It is usually added with a moisture-proofing agent and made into granules to facilitate storage, transportation and application. Ammonium phosphate is suitable for all kinds of crops and soils, especially suitable for crops requiring more phosphorus and phosphorus-deficient soils. When applying ammonium phosphate, the amount of phosphorus should be considered first. The insufficient nitrogen can be supplemented with elemental nitrogen fertilizer. Ammonium phosphate can be used as base fertilizer, top dressing and seed fertilizer. As basal fertilizer and top dressing, generally 10-15? per 667m2 is appropriate, and it can be applied in furrow or hole. As seed fertilizer, 2?-3? per 667m2 is appropriate, but it is not suitable for direct contact with seeds to prevent influence on germination and cause Burn seedlings. The suitable base fertilizer for fruit trees is 2.5? per plant, and the topdressing can be done by extra-root topdressing, and the spraying concentration is 0.5%-1%. Ammonium phosphate cannot be mixed or stored with alkaline substances such as plant ash and lime. Ammonium phosphate must be applied 4-5 days after lime is applied to acid soil to avoid volatilization of nitrogen and reduce the effectiveness of phosphorus. (2) Ammoniated superphosphate In order to eliminate the adverse effects of free acid in superphosphate, a certain amount of ammonia is usually passed into superphosphate to make ammoniated superphosphate. Its main components are NH4H2PO4, CaHPO4 and (NH4)2SO4, containing N2%-3 %, P2O513%-15%. The ammoniated superphosphate is dry, loose, soluble in water (phosphorus is weakly acid-soluble), does not contain free acid, is not corrosive, has weak hygroscopicity and caking properties, has good physical properties and relatively stable properties. The fertilizer effect of ammoniated superphosphate is slightly better than that of superphosphate. It is suitable for all kinds of crops. It has the best effect when applied on acid soil. Be careful not to mix with alkaline substances to prevent the volatilization of ammonia and the degradation of phosphorus. Due to the low nitrogen content, other nitrogen fertilizers should be applied with the same application method as superphosphate. (3) Potassium dihydrogen phosphate Potassium dihydrogen phosphate is a high-concentration phosphate-potassium binary compound fertilizer. The pure product is white or off-white crystals, with a nutrient content of 0-52-34, low hygroscopicity, good physical properties, easy to dissolve in water, and pH3-4 ,expensive. Potassium dihydrogen phosphate is suitable for seed soaking, seed dressing and root topdressing. The seed soaking concentration is 0.2%, and the time is 12 hours. For every 100kg of solution, 30kg of soybeans and 50kg of wheat are soaked. Seed dressing is usually sprayed with a concentration of 1%, and the seeds are planted on the same day. The spraying concentration is 0.2%-0.5%, and the dosage is 50kg-75kg per 667m2. Choose to spray on the foliar surface in the afternoon on a sunny day without dripping onto the ground. Three consecutive sprays were applied for wheat at the jointing and booting stage and cotton before and after flowering. For fruit trees, spraying 0.5% potassium dihydrogen phosphate solution during fruit expansion to coloring period has a good effect on improving product quality. (4) Potassium nitrate Potassium nitrate, commonly known as fire nitrate, is made by dissolving sodium nitrate and potassium chloride together and then recrystallizing or extracting from nitrate soil. Its molecular formula is KNO3. Contains 13% N, 46% K2O. The pure potassium nitrate is white crystal, the crude product is slightly yellowish, hygroscopic, easily soluble in water, and is chemically neutral and physiologically neutral fertilizer. It is easy to explode at high temperature and belongs to flammable and explosive substance. Pay attention to safety when storing, transporting and applying. Potassium nitrate is suitable for dry land topdressing. The dosage is generally 5667m2-10667m2. It has a good fertilizer effect on potatoes, tobacco, sugar beets, grapes, sweet potatoes and other crops that prefer potassium but avoid chlorine. It also responds well to legumes, such as other crops. Crops should be combined with elemental nitrogen fertilizer to improve fertilizer efficiency. Potassium nitrate can also be used as extra-root topdressing, with a suitable concentration of 0.6%-1%. In arid areas, it can also be mixed with organic fertilizer as a base fertilizer, the amount is about 10667m2. Since the N:K2O of potassium nitrate is 1:3.5 and the potassium content is high, the potassium content should be used as the basis for the calculation of fertilizers. The lack of nitrogen can be supplemented by elemental nitrogen fertilizer. (5) Urea ammonium phosphate The composition of urea ammonium phosphate is CO(NH2)2•(NH4)2HPO4, which is made of urea plus ammonium phosphate. Its nutrient content can be 37-17-0, 29-29-0, 25-25-0, etc. It is a high-concentration nitrogen and phosphorus compound fertilizer, in which N and P nutrients are water-soluble, N:P2O5 It is 1:1 or 2:1, easy to be absorbed and utilized by crops. Urea ammonium phosphate is suitable for all types of soil and various crops, and its fertilizer efficiency is better than that of elemental fertilizers with equal nitrogen and phosphorus content, and its application method is the same as that of ammonium phosphate. (6) Ammonium phosphorus potassium fertilizer Ammonium phosphate potassium fertilizer is a ternary compound fertilizer made by mixing ammonium sulfate, potassium sulfate and phosphate in different proportions, or made by adding potassium salt to ammonium phosphate. Due to the different preparation ratios, the nutrient ratios are 12-24 -12, 10-20-15, and 10-30-10. The ratio of phosphorus in ammonium, phosphorus and potassium fertilizers is relatively large, and elemental nitrogen and potassium fertilizers can be appropriately used in conjunction with the application to adjust the ratio to better exert the fertilizer effect. Ammonium phosphorus potassium fertilizer is a high-concentration compound fertilizer, it and potassium nitrate are often used as special fertilizers in tobacco areas. In addition to the above, there are many types of compound (mixed) fertilizers produced in my country, some of which have been widely used in production and have good effects. Various regions should choose appropriate compound fertilizers according to different soil, climate, crops and production conditions. At present, there are phenomena such as soil acidification and compaction in cultivated land. The application of compound fertilizer in combination with microbial fertilizer can not only improve the soil, but also promote high and excellent yields. It is currently a widely recognized new fertilization method.