Controlled-release nitrogen fertilizer applied to crops in arid region

Abstract

The invention relates to the technical field of sustained and controlled release nitrogen fertilizers, and discloses a sustained and controlled release nitrogen fertilizer applied to crops in arid regions, which comprises the following raw materials in parts by weight: 22-28 parts of ammonium nitrate, 18-22 parts of urea, 12-18 parts of ammonium chloride, 6-9 parts of monoammonium phosphate, 6-10 parts of humic acid, 6-10 parts of zeolite powder, 4-6 parts of a water-retaining agent, 1.5-2.5 parts of a nitrification inhibitor, 5-10 parts of a coating material and 1-5 parts of a trace element mixture, the coating material is prepared from 22 to 28 parts of chitosan, 12 to 18 parts of polylactic acid, 6 to 9 parts of bentonite and 11 to 14 parts of polyacrylamide. The nitrogen fertilizer is slowly released through coating treatment, volatilization and leaching loss of nitrogen elements are reduced, the humic acid and the zeolite powder can improve the soil structure, improve the water and fertilizer retention capacity of soil, effectively lock water, reduce water evaporation and fertilizer loss and reduce rapid loss and waste of the nitrogen elements, and therefore the utilization rate of the fertilizer is increased, and the fertilization cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of slow-release and controlled-release nitrogen fertilizers, in particular to slow-release and controlled-release nitrogen fertilizers applied to crops in arid areas. Background Art

[0002] Nitrogen fertilizer is a unit fertilizer that can provide nitrogen nutrition to plants when applied to the soil. Nitrogen fertilizer is the most produced and used type of fertilizer in the world. Appropriate nitrogen fertilizer usage plays an important role in increasing crop yields and improving the quality of agricultural products. In arid areas, agricultural production faces severe challenges of water shortage. Due to scarce and uneven rainfall, the soil moisture content is low, which places extremely high demands on crop growth and the effective use of fertilizers.

[0003] The nitrogen in currently available nitrogen fertilizers is easily lost through volatilization and leaching, which reduces the utilization rate of fertilizers and increases agricultural production costs. In addition, traditional nitrogen fertilizers cannot continuously and stably supply nutrients according to the growth needs of crops, and it is difficult to meet the nitrogen needs of crops in arid areas at different growth stages. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention provides a slow-release nitrogen fertilizer for application to crops in arid areas, which solves the problems of rapid loss and waste of nitrogen and high fertilization cost.

[0005] To achieve the above purpose, the present invention is implemented through the following technical scheme: a slow-release nitrogen fertilizer for crops in arid areas comprises the following raw materials in parts by weight: 22 to 28 parts of ammonium nitrate, 18 to 22 parts of urea, 12 to 18 parts of ammonium chloride, 6 to 9 parts of monoammonium phosphate, 6 to 10 parts of humic acid, 6 to 10 parts of zeolite powder, 4 to 6 parts of water retaining agent, 1.5 to 2.5 parts of nitrification inhibitor, 5 to 10 parts of coating material, and 1 to 5 parts of trace element mixture.

[0006] Preferably, the coating material comprises 22 to 28 parts of chitosan, 12 to 18 parts of polylactic acid, 6 to 9 parts of bentonite, and 11 to 14 parts of polyacrylamide.

[0007] Preferably, the water retaining agent is sodium polyacrylate; Preferably, the trace element mixture includes 2 to 4 parts of zinc, 2 to 4 parts of iron, 2 to 4 parts of manganese, 2 to 4 parts of copper and 2 to 4 parts of boron.

[0008] Preferably, the slow-release nitrogen fertilizer comprises the following preparation steps: Step 1, zinc, iron, manganese, copper and boron in the trace element mixture are mixed evenly for standby use, ammonium nitrate, urea, ammonium chloride and monoammonium phosphate are put into a mixing container, mixed and stirred to make them evenly mixed, and a nitrogen-phosphorus mixture is obtained; Step 2: adding humic acid and zeolite powder to the nitrogen-phosphorus mixture material, mixing the materials evenly, and then using a granulation device to prepare nitrogen-phosphorus mixed particles; dissolving chitosan, polylactic acid, bentonite and polyacrylamide in an organic solvent, stirring evenly, and preparing a coating liquid; Step 3, placing the nitrogen-phosphorus mixed particles into a fluidized bed, spraying the coating liquid to perform coating treatment, taking out the coated material, adding a water retaining agent, a nitrification inhibitor and a pre-mixed trace element mixture, and stirring again for 20 to 25 minutes; Step 4: Dry the final mixed materials to remove excess water to obtain a finished slow-release nitrogen fertilizer.

[0009] Preferably, the nitrogen-phosphorus mixture material comprises the following specific preparation steps: Put ammonium nitrate, urea, ammonium chloride and monoammonium phosphate into a stirring device in sequence, and start the stirring device to mix and stir; Stir the device at 30-40 r / min and maintain at 20-25°C for 25-30 minutes; Finally, the overall color and texture are relatively consistent, and the nitrogen-phosphorus mixed material can be produced without obvious color stratification or particle aggregation.

[0010] Preferably, the nitrogen-phosphorus mixed particles include the following specific preparation steps: Putting the nitrogen-phosphorus mixture into a mixing device, adding deionized water into the mixing device, and continuously stirring, so that the nitrogen-phosphorus mixture forms a uniform soft material under the action of the deionized water; The soft material is passed through the screen of the extruder and extruded into strips, and the strips are cut into small pieces of equal length using a cutting device to form preliminary particles; Put the initially formed granules into an oven, control the drying temperature at 50-70°C, and dry them until the moisture content of the granules is 2%-5%; Finally, the dried particles are screened using a 10-20 mesh sieve, and the particles are graded and screened to obtain nitrogen-phosphorus mixed particles.

[0011] Preferably, the method for preparing the coating material comprises the following steps: Dissolving chitosan and polylactic acid in an organic solvent, and stirring evenly to obtain a mixed solution; Add bentonite, water-retaining material and polyacrylamide into the mixed solution and continue stirring to form a uniform coating emulsion.

[0012] Preferably, the coating treatment is performed by placing the nitrogen-phosphorus mixed particles into a fluidized bed, adjusting the air inlet temperature of the fluidized bed to 50-60°C, and the air volume to 500-800 m³ / h, using a spray gun to evenly spray the coating emulsion into the fluidized bed so that the surfaces of the nitrogen-phosphorus mixed particles contact the coating liquid, and taking the coated particles out of the fluidized bed and placing them in a well-ventilated environment to naturally cool to room temperature.

[0013] Preferably, in step 2, the organic solvent is ethanol, which is used to dissolve and disperse the coating material.

[0014] The present invention provides a slow-release nitrogen fertilizer for crops in arid areas. It has the following beneficial effects: 1. The present invention reduces nitrogen volatilization and leaching losses by slowly releasing nitrogen fertilizer through coating treatment. Humic acid and zeolite powder can improve soil structure, improve soil water and fertilizer retention capacity, effectively lock moisture, reduce water evaporation and fertilizer loss, and reduce rapid loss and waste of nitrogen, thereby improving fertilizer utilization and reducing fertilization costs.

[0015] 2. The combination of natural polymer materials and synthetic polymer materials of the present invention improves the stability and controllability of the coating, the nanoclay enhances the mechanical strength and barrier properties of the coating, and the water-retaining material can effectively retain soil moisture and reduce water evaporation.

[0016] 3. The addition of the trace element mixture of the present invention provides comprehensive nutrition for crops, helps to promote the healthy growth and development of crops, and the use of humic acid and zeolite powder can improve the soil structure and enhance the soil's ability to retain water and fertilizer, thereby delaying nitrogen conversion and prolonging fertilizer effectiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention is a schematic diagram of the combined process of slow-release and controlled-release nitrogen fertilizers applied to crops in arid areas. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Example: Please refer to the attached Figure 1The embodiment of the present invention provides a slow-release nitrogen fertilizer for crops in arid areas, comprising the following raw materials in parts by weight: 22 to 28 parts of ammonium nitrate, 18 to 22 parts of urea, 12 to 18 parts of ammonium chloride, 6 to 9 parts of monoammonium phosphate, 6 to 10 parts of humic acid, 6 to 10 parts of zeolite powder, 4 to 6 parts of water retaining agent, 1.5 to 2.5 parts of nitrification inhibitor, 5 to 10 parts of coating material, and 1 to 5 parts of trace element mixture.

[0020] The coating material comprises 22-28 parts of chitosan, 12-18 parts of polylactic acid, 6-9 parts of bentonite and 11-14 parts of polyacrylamide.

[0021] The water retaining agent is sodium polyacrylate.

[0022] The trace element mixture includes 2 to 4 parts of zinc, 2 to 4 parts of iron, 2 to 4 parts of manganese, 2 to 4 parts of copper and 2 to 4 parts of boron.

[0023] Ammonium nitrate can quickly provide nitrogen to crops and promote the growth of plant stems and leaves; Urea, with high nitrogen content, has a long-lasting and stable fertilizer effect, meeting the long-term nitrogen needs of crops; Ammonium chloride, which increases the chloride ion content in the soil; Monoammonium phosphate provides both nitrogen and phosphorus, which helps the root development and flower bud differentiation of crops and improves the stress resistance of crops; Humic acid improves soil structure, increases soil's ability to retain water and fertilizer, promotes soil microbial activity, and improves soil fertility; Zeolite powder has good adsorption properties and can absorb harmful substances in the soil, adjust the soil pH and improve soil permeability; Sodium polyacrylate can absorb and store a large amount of water, continuously providing water to crops during droughts and reducing water loss; Nitrification inhibitors inhibit the activity of nitrifying bacteria in the soil, slowing down the conversion of ammonium nitrogen to nitrate nitrogen, thereby prolonging the fertilizer effect of nitrogen fertilizer.

[0024] Coating material: Chitosan, which has good film-forming properties and biocompatibility, can control the release rate of nutrients; Polylactic acid is biodegradable, environmentally friendly and can form an effective coating to regulate fertilizer nutrient release; Bentonite, which enhances the stability and adsorption properties of the coating and helps control nutrient release; Polyacrylamide improves the strength and integrity of the coating and ensures the sustained-release effect.

[0025] Trace element mixture: Zinc participates in the synthesis and metabolism of various enzymes in plants, promoting photosynthesis and growth and development; Iron is an essential element for chlorophyll synthesis and affects plant photosynthesis and respiration; Manganese is involved in the photosynthesis, nitrogen metabolism and redox reaction physiological processes of plants; Copper plays an important role in photosynthesis, respiration and protein synthesis of plants; Boron promotes pollen germination and pollen tube elongation, which is beneficial to reproductive growth and fruiting.

[0026] Through slow-controlled release and coating treatment, nitrogen fertilizer can slowly release nutrients according to crop needs, reducing the rapid loss and waste of nitrogen, thereby improving fertilizer utilization and reducing fertilization costs. The addition of trace element mixtures provides comprehensive nutrition for crops and helps promote healthy growth and development of crops.

[0027] The slow-release nitrogen fertilizer includes the following preparation steps: Step 1, zinc, iron, manganese, copper and boron in the trace element mixture are mixed evenly for standby use, ammonium nitrate, urea, ammonium chloride and monoammonium phosphate are put into a mixing container, mixed and stirred to make them evenly mixed, and a nitrogen-phosphorus mixture is obtained; Step 2: adding humic acid and zeolite powder to the nitrogen-phosphorus mixture material, mixing the materials evenly, and then using a granulation device to prepare nitrogen-phosphorus mixed particles; dissolving chitosan, polylactic acid, bentonite and polyacrylamide in an organic solvent, stirring evenly, and preparing a coating liquid; Step 3, placing the nitrogen-phosphorus mixed particles into a fluidized bed, spraying the coating liquid to perform coating treatment, taking out the coated material, adding a water retaining agent, a nitrification inhibitor and a pre-mixed trace element mixture, and stirring again for 20 to 25 minutes; Step 4: Dry the final mixed materials to remove excess water to obtain a finished slow-release nitrogen fertilizer.

[0028] The nitrogen-phosphorus mixture material comprises the following specific preparation steps: Put ammonium nitrate, urea, ammonium chloride and monoammonium phosphate into a stirring device in sequence, and start the stirring device to mix and stir; Stir the device at 30-40 r / min and maintain at 20-25°C for 25-30 minutes; Finally, the overall color and texture are relatively consistent, and the nitrogen-phosphorus mixed material can be produced without obvious color stratification or particle aggregation.

[0029] The nitrogen-phosphorus mixed particles include the following specific preparation steps: Putting the nitrogen-phosphorus mixture into a mixing device, adding deionized water into the mixing device, and continuously stirring, so that the nitrogen-phosphorus mixture forms a uniform soft material under the action of the deionized water; The soft material is passed through the screen of the extruder and extruded into strips, and the strips are cut into small pieces of equal length using a cutting device to form preliminary particles; Put the initially formed granules into an oven, control the drying temperature at 50-70°C, and dry them until the moisture content of the granules is 2%-5%; Finally, the dried particles are screened using a 10-20 mesh sieve, and the particles are graded and screened to obtain nitrogen-phosphorus mixed particles.

[0030] The preparation method of the coating material comprises the following steps: Dissolving chitosan and polylactic acid in an organic solvent, and stirring evenly to obtain a mixed solution; Add bentonite, water-retaining material and polyacrylamide into the mixed solution and continue stirring to form a uniform coating emulsion.

[0031] The coating treatment is carried out by putting the nitrogen-phosphorus mixed particles into a fluidized bed, adjusting the air inlet temperature of the fluidized bed to 50-60°C and the air volume to 500-800m³ / h, and using a spray gun to evenly spray the coating emulsion into the fluidized bed so that the surface of the nitrogen-phosphorus mixed particles contacts the coating liquid. The coated particles are taken out from the fluidized bed and placed in a well-ventilated environment to cool naturally to room temperature.

[0032] In step 2, the organic solvent is ethanol, which is used to dissolve and disperse the coating material.

[0033] The following is an introduction in conjunction with specific embodiments: Embodiment 1: Raw materials by weight: 22 parts of ammonium nitrate, 18 parts of urea, 12 parts of ammonium chloride, 6 parts of monoammonium phosphate, 6 parts of humic acid, 6 parts of zeolite powder, 4 parts of water retaining agent, 1.5 parts of nitrification inhibitor, 5 parts of coating material, 1 part of trace element mixture; Coating materials: 22 parts of chitosan, 12 parts of polylactic acid, 6 parts of bentonite, and 11 parts of polyacrylamide; Trace element mixture: 2 parts zinc, 2 parts iron, 2 parts manganese, 2 parts copper, 2 parts boron.

[0034] Preparation steps: Step 1: Mix the zinc, iron, manganese, copper and boron in the trace element mixture evenly and set aside. Add ammonium nitrate, urea, ammonium chloride and monoammonium phosphate into a mixing container and mix and stir them evenly to obtain a nitrogen and phosphorus mixture. Stir the device at 30r / min and keep it at 20°C for 25 minutes; Step 2: Add humic acid and zeolite powder to the nitrogen-phosphorus mixture, mix the materials evenly, and then use granulation equipment to make nitrogen-phosphorus mixed particles. Dissolve chitosan, polylactic acid, bentonite and polyacrylamide in ethanol, stir evenly, and make a coating solution; Step 3: Place the nitrogen-phosphorus mixed particles into the fluidized bed, adjust the air inlet temperature of the fluidized bed to 50°C and the air volume to 500m³ / h, use a spray gun to evenly spray the coating emulsion into the fluidized bed so that the surface of the nitrogen-phosphorus mixed particles contacts the coating liquid, take out the coated material, add the water retaining agent, nitrification inhibitor and the pre-mixed trace element mixture, and stir again for 20 minutes; Step 4: Dry the final mixed materials to remove excess water to obtain the finished slow-release nitrogen fertilizer. Put the initially formed granules into an oven, control the drying temperature to 50°C, and dry until the moisture content of the granules is 2%. Finally, use a 10-mesh sieve to screen the dried granules, and grade and screen the granules to obtain nitrogen-phosphorus mixed granules.

[0035] Embodiment 2: Raw materials by weight: 25 parts of ammonium nitrate, 20 parts of urea, 15 parts of ammonium chloride, 7.5 parts of monoammonium phosphate, 8 parts of humic acid, 8 parts of zeolite powder, 5 parts of water retaining agent, 2 parts of nitrification inhibitor, 7.5 parts of coating material, 3 parts of trace element mixture; Coating materials: 25 parts of chitosan, 15 parts of polylactic acid, 7.5 parts of bentonite, and 12.5 parts of polyacrylamide; Trace element mixture: 3 parts zinc, 3 parts iron, 3 parts manganese, 3 parts copper, 3 parts boron.

[0036] Preparation steps: Step 1: Mix the zinc, iron, manganese, copper and boron in the trace element mixture evenly and set aside. Add ammonium nitrate, urea, ammonium chloride and monoammonium phosphate into a mixing container and mix and stir them evenly to obtain a nitrogen and phosphorus mixture. Stir the device at 35r / min and maintain at 22.5℃ for 27.5 minutes; Step 2: Add humic acid and zeolite powder to the nitrogen-phosphorus mixture, mix the materials evenly, and then use granulation equipment to make nitrogen-phosphorus mixed particles. Dissolve chitosan, polylactic acid, bentonite and polyacrylamide in ethanol, stir evenly, and make a coating solution; Step 3: Place the nitrogen-phosphorus mixed particles into the fluidized bed, adjust the air inlet temperature of the fluidized bed to 55°C, and the air volume to 650m³ / h, use a spray gun to evenly spray the coating emulsion into the fluidized bed, so that the surface of the nitrogen-phosphorus mixed particles contacts the coating liquid, take out the coated material, add the water retaining agent, nitrification inhibitor and the pre-mixed trace element mixture, and stir again for 22.5 minutes; Step 4: Dry the final mixed materials to remove excess water to obtain the finished slow-release nitrogen fertilizer. Put the initially formed granules into an oven, control the drying temperature to 60°C, and dry them until the moisture content of the granules is 3.5%. Finally, use a 15-mesh sieve to screen the dried granules, and grade and screen the granules to obtain nitrogen-phosphorus mixed granules.

[0037] Embodiment three: Raw materials by weight: 28 parts of ammonium nitrate, 22 parts of urea, 18 parts of ammonium chloride, 9 parts of monoammonium phosphate, 10 parts of humic acid, 10 parts of zeolite powder, 6 parts of water retaining agent, 2.5 parts of nitrification inhibitor, 10 parts of coating material, 5 parts of trace element mixture; Coating materials: 28 parts of chitosan, 18 parts of polylactic acid, 9 parts of bentonite, and 14 parts of polyacrylamide; Trace element mixture: 4 parts zinc, 4 parts iron, 4 parts manganese, 4 parts copper, 4 parts boron.

[0038] Preparation steps: Step 1: Mix the zinc, iron, manganese, copper and boron in the trace element mixture evenly and set aside. Add ammonium nitrate, urea, ammonium chloride and monoammonium phosphate into a mixing container and mix and stir them evenly to obtain a nitrogen and phosphorus mixture. Stir the device at 40r / min and keep it at 25°C for 30 minutes; Step 2: Add humic acid and zeolite powder to the nitrogen-phosphorus mixture, mix the materials evenly, and then use granulation equipment to make nitrogen-phosphorus mixed particles. Dissolve chitosan, polylactic acid, bentonite and polyacrylamide in ethanol, stir evenly, and make a coating solution; Step 3: Place the nitrogen-phosphorus mixed particles into the fluidized bed, adjust the air inlet temperature of the fluidized bed to 60°C and the air volume to 800m³ / h, use a spray gun to evenly spray the coating emulsion into the fluidized bed so that the surface of the nitrogen-phosphorus mixed particles contacts the coating liquid, take out the coated material, add the water retaining agent, nitrification inhibitor and the pre-mixed trace element mixture, and stir again for 25 minutes; Step 4: Dry the final mixed materials to remove excess water and obtain the finished slow-release nitrogen fertilizer. Put the initially formed granules into an oven, control the drying temperature to 70°C, and dry until the moisture content of the granules is 5%. Finally, use a 20-mesh sieve to screen the dried granules, and grade and screen the granules to obtain nitrogen-phosphorus mixed granules.

[0039] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A slow-release nitrogen fertilizer for crops in arid areas, characterized by: The invention comprises the following raw materials in parts by weight: 22-28 parts of ammonium nitrate, 18-22 parts of urea, 12-18 parts of ammonium chloride, 6-9 parts of monoammonium phosphate, 6-10 parts of humic acid, 6-10 parts of zeolite powder, 4-6 parts of water retaining agent, 1.5-2.5 parts of nitrification inhibitor, 5-10 parts of coating material and 1-5 parts of trace element mixture.

2. The slow-release nitrogen fertilizer for crops in arid areas according to claim 1, characterized in that: The coating material comprises 22-28 parts of chitosan, 12-18 parts of polylactic acid, 6-9 parts of bentonite and 11-14 parts of polyacrylamide.

3. The slow-release nitrogen fertilizer for crops in arid areas according to claim 1, characterized in that: The water retaining agent is sodium polyacrylate.

4. The slow-release nitrogen fertilizer for crops in arid areas according to claim 1, characterized in that: The trace element mixture comprises 2 to 4 parts of zinc, 2 to 4 parts of iron, 2 to 4 parts of manganese, 2 to 4 parts of copper and 2 to 4 parts of boron.

5. The slow-release nitrogen fertilizer for crops in arid areas according to claim 1, characterized in that: The slow-release nitrogen fertilizer comprises the following preparation steps: Step 1, zinc, iron, manganese, copper and boron in the trace element mixture are mixed evenly for standby use, ammonium nitrate, urea, ammonium chloride and monoammonium phosphate are put into a mixing container, mixed and stirred to make them evenly mixed, and a nitrogen-phosphorus mixture is obtained; Step 2: adding humic acid and zeolite powder to the nitrogen-phosphorus mixture material, mixing the materials evenly, and then using a granulation device to prepare nitrogen-phosphorus mixed particles; dissolving chitosan, polylactic acid, bentonite and polyacrylamide in an organic solvent, stirring evenly, and preparing a coating liquid; Step 3, placing the nitrogen-phosphorus mixed particles into a fluidized bed, spraying the coating liquid to perform coating treatment, taking out the coated material, adding a water retaining agent, a nitrification inhibitor and a pre-mixed trace element mixture, and stirring again for 20 to 25 minutes; Step 4: Dry the final mixed materials to remove excess water to obtain a finished slow-release nitrogen fertilizer.

6. The slow-release nitrogen fertilizer for crops in arid areas according to claim 5, characterized in that: The nitrogen-phosphorus mixture material comprises the following specific preparation steps: Put ammonium nitrate, urea, ammonium chloride and monoammonium phosphate into a stirring device in sequence, and start the stirring device to mix and stir; Stir the device at 30-40 r / min and maintain at 20-25°C for 25-30 minutes; Finally, the overall color and texture are relatively consistent, and the nitrogen-phosphorus mixed material can be produced without obvious color stratification or particle aggregation.

7. The slow-release nitrogen fertilizer for crops in arid areas according to claim 5, characterized in that: The nitrogen-phosphorus mixed particles include the following specific preparation steps: Putting the nitrogen-phosphorus mixture into a mixing device, adding deionized water into the mixing device, and continuously stirring, so that the nitrogen-phosphorus mixture forms a uniform soft material under the action of the deionized water; The soft material is passed through the screen of the extruder and extruded into strips, and the strips are cut into small pieces of equal length using a cutting device to form preliminary particles; Put the initially formed granules into an oven, control the drying temperature at 50-70°C, and dry them until the moisture content of the granules is 2%-5%; Finally, the dried particles are screened using a 10-20 mesh sieve, and the particles are graded and screened to obtain nitrogen-phosphorus mixed particles.

8. The slow-release nitrogen fertilizer for crops in arid areas according to claim 5, characterized in that: The preparation method of the coating material comprises the following steps: Dissolving chitosan and polylactic acid in an organic solvent, and stirring evenly to obtain a mixed solution; Add bentonite, water-retaining material and polyacrylamide into the mixed solution and continue stirring to form a uniform coating emulsion.

9. The slow-release nitrogen fertilizer for crops in arid areas according to claim 5, characterized in that: The coating treatment comprises putting nitrogen-phosphorus mixed particles into a fluidized bed, adjusting the air inlet temperature of the fluidized bed to 50-60°C, and the air volume to 500-800 m³ / h, using a spray gun to evenly spray the coating emulsion into the fluidized bed, so that the surfaces of the nitrogen-phosphorus mixed particles are in contact with the coating liquid, taking the coated particles out of the fluidized bed, and placing them in a well-ventilated environment to naturally cool to room temperature.

10. The slow-release nitrogen fertilizer for crops in arid areas according to claim 5, characterized in that: In the step 2, the organic solvent is ethanol, which is used to dissolve and disperse the coating material.

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