(2) Phosphate fertilizer: that is, fertilizer with phosphorus as the main component, including ordinary superphosphate, calcium magnesium phosphate and so on.
(3) Potash fertilizer: that is, chemical fertilizer with potassium as the main component is not widely used at present. The main varieties are potassium chloride, potassium sulfate and potassium nitrate.
(4) Compound fertilizer: namely binary compound fertilizer containing two fertilizers and three elements (nitrogen, phosphorus and potassium) and ternary compound fertilizer containing three elements (nitrogen, phosphorus and potassium). Among them, compound fertilizer is rapidly popularized throughout the country.
(5) Trace element fertilizers and some medium element fertilizers: the former contains trace elements such as boron, zinc, iron, molybdenum, manganese and copper, while the latter contains fertilizers such as calcium, magnesium and sulfur.
(6) Fertilizers that are beneficial to some crops: such as steel slag silicon fertilizer applied to rice, cobalt fertilizer applied to leguminous crops, agricultural rare earth applied to sugarcane and fruits, etc.
There are 16 kinds of essential nutrients for crops. Except that hydrocarbons and oxygen are absorbed from the air, the rest need fertilization to meet the needs of normal growth of crops. According to the demand of crops for nutrients, it is divided into a large number of elemental fertilizers, including nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer; Medium element fertilizer, including calcium, magnesium and sulfur fertilizer; Trace element fertilizers, including zinc, boron, manganese, molybdenum, iron and copper fertilizers; In addition, there are some fertilizers from beneficial elements, such as silicon-containing fertilizers and rare earth fertilizers.
At present, the fertilizers distributed in the market are mainly nitrogen, phosphorus and potassium fertilizer, and there are many varieties of each fertilizer. The main nitrogen fertilizers are urea, ammonium bicarbonate (ammonium bicarbonate), ammonium chloride, ammonium sulfate, ammonium nitrate, calcium nitrate, ammonia water and lime nitrogen, which are also nitrogen fertilizers, but they are rarely used at present. Calcium nitrate is not only nitrogen fertilizer, but also calcium fertilizer. The main varieties of phosphate fertilizer are superphosphate (ssp), triple superphosphate (also known as triple superphosphate) and calcium magnesium phosphate. In addition, phosphate rock powder, steel slag phosphate, defluorinated phosphate and bone meal are also phosphate fertilizers, but the current dosage is very small and the market is very small. The main varieties of potash fertilizer are potassium sulfate, potassium chloride, salt lake potash fertilizer, kiln ash potash fertilizer and plant ash. Among them, potassium sulfate and potassium chloride are relatively pure, and most of them are imported fertilizers. Salt Lake potash fertilizer is produced in Qinghai Province, China, and its main components are potash fertilizer, kiln ash potash fertilizer and plant ash, which is very complicated and its circulation in the market is not as good as the first three potash fertilizers. There are also many kinds of trace element fertilizers, the most commonly used boron fertilizer is borax, zinc fertilizer is zinc sulfate, manganese fertilizer is manganese sulfate, molybdenum fertilizer is ammonium molybdate, copper fertilizer is copper sulfate, and iron fertilizer is ferrous sulfate and some organic iron complexes. With the deepening of pesticide research, the application of compound fertilizer is more and more extensive. Compound fertilizer is a fertilizer containing two or more components of nitrogen, phosphorus and potassium at the same time. According to the manufacturing method, it can be divided into compound fertilizer and mixed fertilizer. The most common compound fertilizer is diammonium hydrogen phosphate (ammonium phosphate), in addition to urea ammonium phosphate, ammonium phosphate, ammonium sulfate, nitrophosphate, diammonium phosphate, potassium nitrate and so on. When using compound fertilizer, the proportion of nutrients should be adjusted to meet the requirements of different crops and soils. Mixed fertilizer is a kind of fertilizer which is made by mechanically mixing several simple fertilizers into different specifications according to the situation of crops and soil. At present, most of the special fertilizers sold in the market belong to this kind of fertilizer.
In addition, all kinds of liquid fertilizers and spraying fertilizers currently on the market are also a mixture of various nutrient elements and fertilizers, and some organic components such as amino acids are added, which also plays a certain role in improving crop yield and quality.
There are 16 kinds of nutrient elements needed for plant growth, namely, nitrogen, phosphorus, potassium, sulfur, calcium, magnesium, carbon, hydrogen, oxygen, boron, iron, molybdenum, copper, zinc, manganese and chlorine, among which nitrogen, phosphorus and potassium are macro elements and the rest are trace elements. Although the demand of plants for these elements varies greatly, they play an important role in plant growth and development. There are many kinds of chemical fertilizers, and the main ones commonly used in production are as follows.
1, nitrogen fertilizer
Nitrogen is the main element of protein, and protein is the basic substance of cell protoplasm. Increasing nitrogen application can promote the formation of protein and chlorophyll, make the leaves dark green, increase the leaf area, promote carbon assimilation, increase yield and improve quality. Nitrogen fertilizers commonly used in production are:
① Ammonium sulfate (ammonium sulfate): white or light brown crystals. The nitrogen content is 20%-2 1%, which is easily soluble in water, with low hygroscopicity and convenient storage and use. Ammonium sulfate is an acidic fertilizer, and long-term use will increase the acidity of soil. It is best to use topdressing, and the general application rate is 667 m2 15-20k g.
② Ammonium bicarbonate (ammonium bicarbonate): white fine crystal, containing nitrogen 17%, with strong pungent smell, easily soluble in water, easily absorbed by crops and easily decomposed and volatilized. Can be used as base fertilizer or topdressing. When topdressing, it should be buried and covered in time to avoid ammonia volatilization and fever.
③ Urea: white and round, with nitrogen content of 46%. Urea is not as effective as ammonium sulfate, and it should be applied a few days earlier than ammonium sulfate when topdressing. Urea is a solid nitrogen fertilizer with the highest nitrogen content. Urea is a neutral fertilizer with no by-products, and it will not destroy the soil structure after years of application.
2. Phosphate fertilizer
Phosphorus is an indispensable element to form nucleoprotein, lecithin and so on. Phosphorus can accelerate cell division, root and bud growth, flower bud differentiation, early maturity and improve fruit quality. Phosphate fertilizers commonly used in production are:
① Calcium superphosphate: grayish white or light gray powder, also in granular form, containing P2O512%-18%. It is hygroscopic and corrosive. After being applied to the soil, it is easy to be fixed by the soil and reduce the fertilizer efficiency. Can be used as base fertilizer and topdressing. It can be applied centrally or mixed with organic fertilizer, which can reduce phosphorus fixation and improve fertilizer efficiency. It can also be used as topdressing outside the roots, so that crops can directly absorb it.
② Double superphosphate (triple superphosphate): It contains about 45% P2O5, and is an efficient phosphate fertilizer. The effective method of applying superphosphate is the same as that of superphosphate. The content of active ingredients in calcium superphosphate is high, and the dosage should be relatively reduced.
3. Potash fertilizer
The nutritional function of potassium can improve the intensity of photosynthesis, promote the formation of starch and sugar in crops, enhance the stress resistance and disease resistance of crops, and improve the absorption and utilization of nitrogen by crops. Potassium fertilizers commonly used in production are:
① Potassium chloride: It is a kind of quick-acting potassium fertilizer which is easily soluble in water. It contains about 60% K2O and has white, light yellow or purplish red crystals. It has good physical properties and can be used as base fertilizer and topdressing. Potassium chloride application in acid soil should be combined with lime and organic fertilizer.
② Potassium sulfate: white crystal, soluble in water, containing about 50%-52% K2O. Besides being used as base fertilizer and topdressing, it can also be used as topdressing outside the root, and the suitable concentration of topdressing outside the root is 0.2%.
4. Compound fertilizer: The chemical fertilizer mentioned above generally contains only one nutrient element and belongs to a single element fertilizer. Compound fertilizer refers to chemical fertilizer containing nitrogen, phosphorus and potassium or only any two of them. It has the advantages of high nutrient content, few by-products, uniform nutrient release, stable and lasting fertilizer effect and convenient storage and application.
① ammonium phosphate: it is a nitrogen-phosphorus compound fertilizer with phosphorus as the main component, containing nitrogen 12% ~ 18% and p205 46% ~ 56%. It is suitable for all kinds of crops and soils, and it is most suitable for strip application as base fertilizer. The dosage is 7-65,667 square meters and 438+00 kg, and 25-25 kg is used as base fertilizer. Among them, monoammonium phosphate is acidic and diammonium phosphate is alkaline, which are easily soluble in water, and the aqueous solution is neutral and has certain hygroscopicity.
② NPK compound fertilizer: each grain contains about 65438 00% nitrogen, phosphorus and potassium, and it is light brown. Both nitrogen and potassium are water soluble, and some phosphorus is water soluble. Mainly used as base fertilizer, the dosage is 667 square meters and 25 ~ 30 kilograms.
③ Potassium dihydrogen phosphate: containing P2O5 24%% and K2O2 1%, white, easily soluble in water, generally used for soilless seedling raising and soilless culture of cucumber. Because of its high price, it is often used for topdressing outside the roots in large-scale production.
(48) How to identify common fertilizers?
1, urea
Appearance is granular or crystalline, easy to absorb moisture, absorb moisture in the air and deliquesce, easily soluble in water and ammonia. Put an iron sheet on the stove with urea particles on it. Urea will melt and evaporate quickly, with a little white smoke and the smell of ammonia. The agricultural total nitrogen content (calculated on a dry basis) is 46.0%. ?
2. Ammonium sulfate?
The appearance is white or light crystal, easy to absorb moisture, soluble in water, and the aqueous solution is acidic. When dissolved in water, it absorbs heat and reacts with alkali to release ammonia. When heated on fire, it melts slowly compared with urea, ammonium nitrate and ammonium chloride. It can also be identified by the reaction of barium chloride with ammonium sulfate in aqueous solution to produce white precipitate. The agricultural ammonia content (calculated on a dry basis) is 2 1.0% for the first-class product and 20.8% for the second-class product. ?
3. ammonium nitrate?
White or yellowish in appearance, easily soluble in water, absorbing a lot of heat to reduce the temperature of water, so it has strong hygroscopicity and cohesiveness. A large amount of ammonium nitrate can burn or even explode when it is decomposed by heat, and produce white smoke, which can smell ammonia. The total nitrogen content in agriculture (calculated on a dry basis) is 34.4%-34.6%. ?
4. ammonium chloride?
Appearance is white or yellowish crystal, easily soluble in water, solubility increases significantly with the increase of temperature, hygroscopicity is strong, easy to agglomerate, and the aqueous solution is acidic. When a small amount of ammonium chloride is heated on a fire, it can smell a strong pungent smell accompanied by white smoke. Ammonium chloride will melt quickly and disappear completely, and the unmelted part will be yellow during the melting process. The agricultural total nitrogen content (dry basis) is 25%. ?
5. Ammonium bicarbonate for agriculture?
The appearance is white or light gray crystal, with ammonia smell, strong hygroscopicity, easy to dissolve in water, and the aqueous solution is weakly acidic. When identifying, you can rub a small amount of samples with your fingers and smell a strong ammonia smell. Agricultural nitrogen content is 65438 07%. ?
6. calcium superphosphate?
The appearance is dark gray, grayish white, light yellow and other loose powder, slightly sour, belonging to acid fertilizer, sensitive to the action of alkali, and easy to lose fertilizer efficiency. Part of it can be dissolved in water, and the aqueous solution is acidic. Under normal circumstances, the hygroscopicity is small. If the air humidity reaches above 80%, it will absorb moisture and form lumps. The effective phosphorus pentoxide content of super grade product is 20%, that of Grade A is 13%, and that of Grade B is 12%. ?
7. Calcium magnesium phosphate fertilizer?
The appearance is grayish white, grayish green or grayish black powder, and the powder is extremely fine. In the sun, you can usually see broken glass-like objects and glow. Insoluble in water, not easy to lose, not hygroscopic, non-toxic, non-corrosive, heated in fire, unchanged, melting point is about 65438 035 degrees Celsius. Super effective phosphorus pentoxide 20%, calcium oxide 40%, magnesium oxide 12%. ?
8. compound fertilizer?
The appearance is grayish brown or grayish white particles. Some compound fertilizers contain white granular crystalline urea, which is not completely crushed, and some compound fertilizers contain complete granular crystalline urea alone. Slightly hygroscopic, compound fertilizer particles are easy to crush after absorbing moisture. Non-toxic, tasteless and non-corrosive. Nitrogen fertilizer, potassium fertilizer and water-soluble phosphorus in some phosphate fertilizers are soluble in water. When heated on a fire, you can see white smoke and smell ammonia, but it can't completely melt. ?
9. ammonia?
It is an aqueous solution of ammonia dissolved in water. It is a colorless, transparent or yellowish liquid with strong pungent smell and toxicity. The aqueous solution is weakly alkaline. The ammonia content in agricultural ammonia water is generally 15%.