According to the compound form: ammonium nitrogen fertilizer, nitrate nitrogen fertilizer, amide nitrogen fertilizer. (A) Ammonium nitrogen fertilizer: Nitrogen compounds containing ammonium ions (NH4+) or ammonia (NH3). Including ammonium bicarbonate (NH4CO3), ammonium sulfate ((NH4)2SO4), ammonium chloride (NH4Cl), ammonia (NH4OH), liquid ammonia (NH3) and so on. 1. Common features: (1) Easily soluble in water, it is a quick-acting nutrient, crops can be directly absorbed and utilized, and fertilizer efficiency is quick. (2) NH4+ is adsorbed by soil colloids to form exchangeable nutrients with low mobility and leaching loss. (3) Ammonia volatilization loss occurs due to decomposition of alkaline materials. When used, it cannot be mixed with alkaline fertilizers; it prevents volatilization during storage and transportation (used after sealing and bag opening); calcareous soil covers the soil deeply. (4) In well ventilated soils, nitrification is prone to the formation of nitrate nitrogen. (5) Fertilizer effect is slower but longer than nitrate-nitrogen fertilizer. It can be used as top dressing or base fertilizer. 2. Common ammonium nitrogen fertilizer: (1) liquid ammonia: liquid ammonia, the composition of NH3, containing N 82.3%, at room temperature and pressure under the gas, it is stored in a pressure vessel. Chemically alkaline, with strong corrosion and irritation, do not make direct contact with the skin. As a basal fertilizer, deep application is not suitable for top dressing and seed dressing. Anti-volatilization. (2) Ammonia: Molecular formula NH3H2O, 12-17% nitrogen, liquid, volatile, irritating ammonia odor, chemical alkaline (PH greater than 10). Can be used as basal fertilizer, top dressing, not as a fertilizer. Deeply applied after the dilution and covered with soil, adding the adsorbent material can prevent evaporation. (3) Ammonium bicarbonate: The molecular formula NH4HCO3 contains about 17% nitrogen. Aqueous fertilizer solution is alkaline reaction; chemical properties are unstable, easy to decompose volatile loss of ammonia, prone to deliquescence, agglomeration, no residual components, known as "gas fertilizer." Can be used as basal fertilizer, top dressing, not as a fertilizer. When fertilizing, it will leave the soil and the two will not leave the water. (4) Ammonium sulfate: The molecular formula NH4SO4 is generally called standard nitrogen fertilizer. Contains 20 to 21% of N. Aqueous fertilizer solution is weakly acidic reaction; physical properties are good (not hygroscopic, no agglomeration), and it belongs to physiological acidic fertilizer, which will cause soil acidification after long-term application alone. Suitable for base fertilizer, top dressing and seed fertilizer, suitable for all kinds of crops, Xi sulfur crops have better application effect. When applied, it is not suitable for long-term use alone, and calcareous soil or paddy field should be applied deeply. Paddy field should not be applied for a long time. (5) Ammonium chloride: Molecular formula NH4Cl, containing 24 to 25% of N. The aqueous solution of fertilizer showed a weak acid reaction; physical properties were better, and the hygroscopicity was slightly larger than that of ammonium sulfate, which was a physiological acidic fertilizer. Suitable for basal fertilizer, top dressing, not suitable for fertilizer. Do not apply chlorine crops when applied, rice fields can be long-term application. (b) Nitrate nitrogen fertilizer: Nitrogen-containing compounds containing nitrate ions (NO3-). Including ammonium nitrate, sodium nitrate, calcium nitrate and so on. 1. Common features: (1) white crystal, soluble in water, is a fast-acting nitrogen fertilizer. (2) It is not easy to be adsorbed by soil colloids and it is easy to be lost. (3) Denitrification occurs under anaerobic conditions, producing N2, N2O, and other loss nitrogen. (4) Large hygroscopicity and poor physical properties. (5) Explosive, flammable, safety measures should be taken during storage and transportation. 2. Commonly used nitrate nitrogen fertilizer: (1) Ammonium nitrate: Molecular formula NH4NO3, containing 33-34% N. The aqueous solution of the fertilizer is weakly acidic; after being applied to the soil, both NH4+ and NO3- can be absorbed by the crop. Suitable for top dressing, not suitable for base fertilizer and seed fertilizer. Suitable for a variety of crops and soil. When applied, it should not be mixed with organic fertilizers. It is easy to cause anaerobic conditions and nitrification. It is not suitable for paddy fields to avoid the loss of nitrate nitrogen and nitrogen loss due to denitrification. (2) Sodium Nitrate: Also known as Chile Saltpeter, formula NaNO3, containing N14-15%. Aqueous fertilizer solution is alkaline reaction, physiological alkaline fertilizer; suitable for top dressing, should be used several times. When applied, economic crops, especially Na+ crops, such as radish, sugar beet, cruciferous crops, have good application effects, contain Na+, are suitable for neutral and acidic soils, and are not suitable for application on saline-alkali soils. (3) Calcium Nitrate: Also known as the Norwegian nitrate salt, molecular formula Ca(NO3)2, containing N13-15%. Aqueous fertilizer solution is weakly alkaline reaction; hygroscopicity is extremely strong, should be stored in a dry and ventilated place; physiological alkaline fertilizer, containing Ca2+, can improve the physical properties of the soil; suitable for top dressing, not for seed fertilizer. Suitable for all kinds of soils, especially calcium-deficient acidic soils, is not suitable for application on paddy fields. In addition, it can be used as a top-dressing fertilizer to increase the yield, quality and storage performance of fruit trees and vegetables such as grapes, apples and tomatoes. (III) Amide nitrogen fertilizer: Urea: Molecular formula CO(NH2)2, containing N44-46%. Solid fertilizer The highest quality nitrogen fertilizer is chemically synthesized organic small molecule compounds. Soluble in water, neutral aqueous solution; deliquescent under high temperature and humidity. Physiologically neutral fertilizers are absorbed into the soil in molecular form after being applied to the soil, and most of them are converted into (NH4)2CO3 by the action of urease. The fertilizer effect is slower than that of NH4+-N and NO3--N. When used as top dressing, it must be advanced 4 -5 days of application; no adverse reactions to soil. Can be used as basal fertilizer, top dressing, not as a seed fertilizer, the most suitable for extra-root top dressing; suitable for all kinds of soil and crops, lime and alkaline soil application of deep cover, prevent the volatilization of ammonia. (D) Long-term nitrogen fertilizer: Also known as slow or slow-release nitrogen fertilizer, controlled nitrogen fertilizer, difficult to dissolve in water or difficult to be decomposed by microorganisms, slow release nutrients in the soil. 1. Common points: (1) Low solubility, slow nutrient release, reduced nitrogen leaching, volatilization, fixation and denitrification losses. (2) The fertilizer is stable and long-lasting, which can meet the supply of nitrogen for the whole growing period of crops. (3) It can be used in large quantities at one time, saving labor and labor. 2. Main types: (1) Urea Formaldehyde (Code UF): Organic long-acting nitrogen fertilizer, containing 32-38% of N, is generally applied on sandy soil and can be used as basal fertilizer, but it must be combined with available nitrogen fertilizer at the early growth stage of annual plants. It is only used in parks, ornamental plants and fruit trees in foreign countries. (2) Urea Isobutyraldehyde (Code IBDU): Organic long-acting nitrogen fertilizer containing N31% in granular form, not hygroscopic, insoluble in water. Applicable to all kinds of crops, generally as basal fertilizer, utilization rate is twice as high as that of urea formaldehyde, but it is necessary to apply quick-acting nitrogen fertilizer in the early stage of crop growth; it is a good source of nitrogen for rice. (3) Oxalamide (Code OA): Organic long-acting nitrogen fertilizer containing 31.8% N, granular, slightly soluble in water. (4) Sulfur-coated urea (codenamed SCU): Coated fertilizer, containing N34-35%, coated with sulphur on the surface of urea granules, and coated with paraffin. The main components are urea 76%, sulphur 19%, paraffin 2%, coal tar 0.25%, and kaolin 1.5%. Urea is diffused out of the pores of the sour clothes after being applied to the soil. The United States, Japan, and the United Kingdom are more rare in China. (5) Calcium magnesium phosphate coated with ammonium bicarbonate: Coated fertilizer, coated with calcium magnesium phosphate fertilizer on the surface of ammonium bicarbonate, containing N14~15%, P2O5 3~5%, 80% of which is available phosphorus, the effect of paddy field it is good. (6) Long-acting urea: In addition to urea, urease inhibitors are added. The properties are the same as those of urea. They are particularly suitable for bases and fertilizers in paddy field and can also be used in paddy fields. Second, the rational use of nitrogen fertilizer 1. Purpose: To increase the nitrogen use efficiency. Nitrogen fertilizer utilization refers to the percentage of nutrient absorption of nitrogen fertilizers by crops after applying nitrogen fertilizer. China currently has 40 to 60% of dry fields and 30 to 45% of paddy fields, averaging about 50%. 2. The way of nitrogen fertilizer loss: decomposition and volatilization of ammonium nitrogen fertilizer, nitrate nitrogen fertilizer leaching and denitrification. 3. The main measures to increase nitrogen use efficiency: (1) Deep application of earth cover: increase the absorption of NH4+ to reduce volatilization, in order to ensure the supply of plants can be applied several days early. Depth varies with the amount of use, and less (fertilizer 75-112.5kg per hectare) should be shallow, more (fertilizer 300-375kg per hectare) can be deep (12 ~ 15cm). In the spring, ridged corn or sorghum is applied deep into a furrow, but it is no longer suitable for top dressing. (2) Regulation of water: Within a certain range of soil moisture, the utilization rate increases with the increase of water content. When applying topdressing, the dry land can be adjusted by irrigation, and when there is no irrigation, the flood season can be seen; the paddy field cannot be flooded. (3) Spheroidization or slow-down of nitrogen fertilizer: The nitrogen fertilizer is blended with decomposed farmyard manure or fertile fine soil and processed into ball-shaped ball fertilizer. The specific surface area of ​​the spherical fertilizer is reduced, releasing nutrients is slower than powder, local concentration is high, and fertilizer efficiency is long. Pay attention when using. Can be used as basal fertilizer or top dressing, deep application, should sooner rather than later. (4) Ammonium nitrogen fertilizer combined with nitrification inhibitors: control the nitrification of ammonium nitrogen. (5) Rationally allocate and select fertilizers: According to the characteristics of crops fertilization: due to crop selection of fertilizers, cereals, leafy vegetables, green feed corn need more nitrogen, but also many soybeans can be nitrogen, so the initial use of a small amount of nitrogen can be; fertilizer-resistant varieties of multiple applications, and vice versa; Some crops like NH4-N, some like NO3-N. Fertilization according to soil conditions: Because the soil is selected for fertilizer, it is mainly PH. Lime soil and alkaline earth shall be treated with NH4—N, and soil shall be covered immediately and physiological acid fertilizer shall be selected; NO3—N fertilizer shall not be applied in paddy field, and fertilizer containing Na+, Cl— shall not be applied in saline soil. Pay attention to balanced fertilization: promote the application of nitrogen, phosphorus, potassium and organic fertilizers, according to the characteristics of the crop and the nature of the fertilizer, properly arrange the base fertilizer, seed fertilizer and topdressing fertilizer to achieve the balance of nutrients and improve the economic benefits of fertilizer. Replacement Trojan UV 3000 Plus Replacement Trojan UV 3000 Plus, Trojan UV Lamps, Trojan UV 3000 Lamp, Trojan UV 3000 Plus Lamp Ningbo Sunfine UV lighting Co.,ltd. , http://www.uvlightings.com