Preparation method of a highly active urea-based compound fertilizer

Abstract

This application relates to the field of compound fertilizer production, and specifically discloses a preparation method of a highly active urea-based compound fertilizer, specifically as follows: Step 1, melt urea and then mix it evenly with the remaining components to obtain a mixed slurry; Step 2, granulate the mixed slurry and cool it to obtain fertilizer; Step 3, spray the fertilizer with an anti-caking agent to obtain the product; The highly active urea-based compound fertilizer includes the following components: urea, vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax, and nitrification inhibitor; The addition of the anti-caking agent makes the compound fertilizer not easily caking due to moisture absorption, thereby achieving the purpose of preventing the urea-based compound fertilizer from caking.

Description

Technical Field

[0001] This application relates to the field of compound fertilizer production. More specifically, it relates to a preparation method of a highly active urea-based compound fertilizer. Background Art

[0002] Urea-based compound fertilizer is a high-concentration nitrogen, phosphorus, and potassium multi-component compound fertilizer produced by secondary processing using urea as the nitrogen source and basic fertilizers such as potassium chloride, potassium sulfate, and ammonium phosphate as raw materials. Common production methods include extrusion method, granulation method, slurry method, and melt method, etc.

[0003] In urea-based compound fertilizer, since urea is a linear straight-chain crystal, it is easy to form regular hexagonal crystals, and there are many pores inside these crystal lattices. As a result, urea crystals have strong water absorption due to capillary adsorption, and thus the surface of urea is easily deliquesced and caked, leading to the caking phenomenon of urea-based compound fertilizer. Summary of the Invention

[0004] In order to make the urea-based compound fertilizer not easily caked, this application provides a preparation method of a highly active urea-based compound fertilizer.

[0005] A preparation method of a highly active urea-based compound fertilizer provided by this application adopts the following technical scheme:

[0006] A preparation method of a highly active urea-based compound fertilizer includes the following steps:

[0007] S1. Melt urea, and then mix it evenly with the remaining components to obtain a mixed slurry;

[0008] S2. Granulate the mixed slurry and cool it to obtain fertilizer;

[0009] S3. Spray the fertilizer with an anti-caking agent to obtain the product; the highly active urea-based compound fertilizer includes the following components: urea, vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax, and nitrification inhibitor.

[0010] By adopting the above technical solutions, trace elements such as boron and zinc play an important regulatory role in the growth and development of plants. They can improve the activity of enzymes in plants, promote photosynthesis and metabolism of plants, thereby enhancing the overall activity of the urea-based compound fertilizer; humic acid has strong chelating ability and ion exchange ability, can form stable chelates with nutrients in the fertilizer, improve the effectiveness of nutrients and further enhance the activity of nutrients in the fertilizer. At the same time, humic acid can also promote the growth and development of plant roots and enhance the nutrient absorption ability of plants; monoammonium phosphate has high water solubility and nutrient effectiveness, and potassium sulfate is used as the potassium source, which can ensure the supply of potassium element to plants and has high activity; in addition, vermiculite powder has strong ion exchange ability and adsorption performance, can adsorb nutrients such as ammonium ions, fix them in the crystal lattice structure of vermiculite, reduce the volatilization and leaching loss of nutrients, improve the nutrient retention ability of the fertilizer, and achieve the slow-release effect; the addition of the anti-caking agent makes the compound fertilizer not easy to caking due to moisture absorption, thus achieving the purpose of preventing the urea-based compound fertilizer from caking.

[0011] Preferably, the mass parts of each material component of the high-activity urea-based compound fertilizer are as follows: 43-48 parts of urea, 1-1.5 parts of vermiculite powder, 20-25 parts of monoammonium phosphate, 20-26 parts of potassium sulfate, 10-15 parts of humic acid, 3-5 parts of urease inhibitor, 3-5 parts of phosphorus activator, 0.5-5 parts of agricultural selenium fertilizer, 0.5-8 parts of zinc sulfate, 0.5-4 parts of borax, 1-2 parts of nitrification inhibitor and 1-3 parts of anti-caking agent.

[0012] Preferably, the anti-caking agent is stearate.

[0013] By adopting the above technical solutions, stearate has hydrophobicity. It can form a thin hydrophobic film on the surface of fertilizer particles, which can prevent fertilizer particles from absorbing moisture in the air, reduce caking caused by moisture absorption, and keep the fertilizer particles in a loose state; in addition, stearate can combine with nutrients such as nitrogen, phosphorus and potassium in the fertilizer to form a relatively stable structure. Therefore, after the fertilizer is applied to the soil, water and microorganisms in the soil need to first break the protective film formed by stearate or the combined structure with the fertilizer before the nutrients of the fertilizer can be released, thus prolonging the release time of fertilizer nutrients; during the fertilizer production process, part of the stearate is adsorbed on the surface of fertilizer particles to achieve the water-blocking effect, and the other part will fill into the tiny voids of fertilizer particles, making the structure of fertilizer particles more compact, thereby enhancing the compressive strength of fertilizer particles and reducing the situation of particle breakage during transportation and loading and unloading of fertilizers.

[0014] Preferably, the stearate is zinc stearate.

[0015] By adopting the above technical solution, zinc stearate can interact with soil particles, promote the aggregation of soil particles through physical adsorption, electrostatic interaction, etc., improve the aggregation and aeration of the soil, be beneficial to the growth and respiration of plant roots, and create a good soil environment for plant growth.

[0016] Preferably, the nitrification inhibitor includes dicyandiamide and nitrapyrin, and the mass ratio of dicyandiamide to nitrapyrin is 1:(1 - 1.5).

[0017] By adopting the above technical solution, in the soil, after nitrogen fertilizers such as urea are applied, they will undergo a series of transformation processes. Among them, ammonium nitrogen is easily oxidized to nitrate nitrogen under the action of ammonia monooxygenase of nitrifying bacteria. Nitrate nitrogen cannot be adsorbed by soil colloids and is easily lost with water (such as leaching caused by rainfall or irrigation), or is volatilized and lost by being converted into gases such as nitrogen through denitrification under specific conditions (such as good soil aeration). The nitrification inhibitor can inhibit the activity of nitrifying bacteria and slow down the conversion rate of ammonium nitrogen to nitrate nitrogen; ammonia monooxygenase is a trimeric membrane-bound protein composed of three subunits. The chemical structure of dicyandiamide enables it to match the active site of ammonia monooxygenase in terms of spatial structure and chemical properties, thus having a certain affinity and being able to specifically bind to this active site, thereby blocking the process of ammonia nitrogen being converted into nitrite; nitrapyrin can chelate Cu on the active site of ammonia monooxygenase of nitrifying bacteria, affect the activity of ammonia monooxygenase, and when used in combination with dicyandiamide, can inhibit nitrification from different angles, thereby indirectly increasing the binding efficiency of dicyandiamide to ammonia monooxygenase; in addition, the zinc ions in zinc stearate can act as a bridge during the action of dicyandiamide to form coordination bonds with specific amino acid residues of ammonia monooxygenase to promote the binding of dicyandiamide to ammonia monooxygenase, thereby enhancing the effect of the nitrification inhibitor; in addition, the zinc ions of zinc stearate are consumed in this process to reduce the catalytic effect of zinc stearate on the condensation reaction of urea and reduce the amount of biuret.

[0018] Preferably, the urease inhibitor is yucca extract.

[0019] By adopting the above technical solution, urea is a commonly used high-concentration nitrogen fertilizer and is easily decomposed by urease in the soil to produce ammonia and volatilize and lose. Yucca extract has the effect of inhibiting urease activity. When used in combination with urea, it can effectively slow down the hydrolysis rate of urea, reduce ammonia volatilization, and improve the utilization rate of urea. At the same time, yucca extract can also promote the absorption and assimilation of nitrogen by plants and enhance the fertilizer efficiency of nitrogen fertilizers.

[0020] Preferably, in S1, humic acid is dissolved in water to obtain a mixture, and then an urease inhibitor is mixed with the mixture and dried to obtain a prefabricated product; urea is melted, and then vermiculite powder, monoammonium phosphate, potassium sulfate, the prefabricated product, a phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax, and a nitrification inhibitor are sequentially added and mixed evenly to obtain a mixed slurry.

[0021] By adopting the above technical solution, the pre-mixing of humic acid and yucca extract enables a protective film to be formed on the surface of the yucca extract by the humic acid, reducing the contact between ultraviolet rays and the yucca extract, so that the ultraviolet rays are not likely to decompose the yucca extract, thereby improving the overall stability of the fertilizer.

[0022] Preferably, in S1, a part of vermiculite powder is mixed evenly with an urease inhibitor to obtain a first mixture, and humic acid is dissolved in water to obtain a second mixture. Then, the first mixture and the second mixture are mixed evenly and dried to obtain a prefabricated product; urea is melted, and then the remaining vermiculite powder, monoammonium phosphate, potassium sulfate, the prefabricated product, a phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax, and a nitrification inhibitor are sequentially added and mixed evenly to obtain a mixed slurry.

[0023] By adopting the above technical solution, the pre-mixing of vermiculite powder and an urease inhibitor enables part of the urease inhibitor to adhere to the surface of the vermiculite powder. Since the vermiculite powder can absorb heat during the day and release heat at night, the temperature change of the soil is smaller, thereby reducing the influence of soil temperature change on the activity of the urease inhibitor.

[0024] In summary, the present application has the following beneficial effects:

[0025] 1. Trace elements such as boron and zinc play an important regulatory role in the growth and development of plants, can improve the activity of enzymes in plants, promote photosynthesis and metabolism of plants, thereby enhancing the overall activity of the urea-based compound fertilizer; humic acid has strong chelating ability and ion exchange ability, can form stable chelates with nutrients in the fertilizer, improve the effectiveness of nutrients and further enhance the activity of nutrients in the fertilizer. At the same time, humic acid can also promote the growth and development of plant roots and enhance the nutrient absorption ability of plants; monoammonium phosphate has high water solubility and nutrient effectiveness, and potassium source uses potassium sulfate, which can ensure the supply of potassium element to plants and has high activity; in addition, vermiculite powder has strong ion exchange ability and adsorption performance, can adsorb nutrients such as ammonium ions, fix them in the crystal lattice structure of vermiculite, reduce the volatilization and leaching loss of nutrients, improve the nutrient retention ability of the fertilizer, and achieve the slow-release effect; the addition of an anti-caking agent makes the compound fertilizer not easily caked due to moisture absorption, thereby achieving the purpose of preventing the urea-based compound fertilizer from caking.

[0026] 2. The premixing of humic acid and yucca extract enables humic acid to form a protective film on the surface of yucca extract, reducing the contact between ultraviolet rays and yucca extract, so that ultraviolet rays are not likely to decompose yucca extract, thereby improving the overall stability of the fertilizer. Detailed implementation manners

[0027] The present application will be further described in detail below with reference to examples and comparative examples. All raw materials used in the present application are commercially available. Among them, humic acid is purchased from Jinan Jiayang Chemical Co., Ltd., agricultural selenium fertilizer is purchased from Qingdao Pengyang Biotechnology Co., Ltd., borax is purchased from Chengdu Zhongpeng Chemical Co., Ltd., N-butyl thiophosphoryl triamide is purchased from Shandong Xiya Chemical Co., Ltd., biochar is purchased from Henan Lize Environmental Protection Technology Co., Ltd., trichloromethylpyridine is 2-chloro-6-trichloromethylpyridine purchased from Wuhan Simac Biotechnology Co., Ltd., liquid paraffin is purchased from Xiamen Minghuiyang Chemical Co., Ltd., and yucca extract is purchased from Shandong Huachang Animal Health Products Co., Ltd.

[0028] Examples

[0029] Example 1

[0030] A preparation method of a high-activity urea-based compound fertilizer includes the following steps:

[0031] S0. Weigh each material according to parts by weight: 43 kg of urea, 1 kg of vermiculite powder, 20 kg of monoammonium phosphate, 20 kg of potassium sulfate, 10 kg of humic acid, 3 kg of urease inhibitor, 3 kg of phosphorus activator, 0.5 kg of agricultural selenium fertilizer, 0.5 kg of zinc sulfate, 0.5 kg of borax, 0.5 kg of anti-caking agent, and 1 kg of nitrification inhibitor. The urease inhibitor is N-butyl thiophosphoryl triamide, the phosphorus activator is biochar, the nitrification inhibitor is trichloromethylpyridine, and the anti-caking agent is liquid paraffin;

[0032] S1. Melt urea at 130 °C, and then successively add vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax, and nitrification inhibitor and mix evenly to obtain a mixed slurry;

[0033] S2. Granulate the mixed slurry and cool it to 45 °C to obtain the fertilizer;

[0034] S3. Spray the fertilizer with the anti-caking agent to obtain the product.

[0035] Example 2

[0036] A preparation method of a high-activity urea-based compound fertilizer includes the following steps:

[0037] S0. Weigh each material by weight parts: 48 kg of urea, 1.5 kg of vermiculite powder, 25 kg of monoammonium phosphate, 26 kg of potassium sulfate, 15 kg of humic acid, 5 kg of urease inhibitor, 5 kg of phosphorus activator, 5 kg of agricultural selenium fertilizer, 8 kg of zinc sulfate, 4 kg of borax, 4 kg of anti-caking agent, and 2 kg of nitrification inhibitor. The urease inhibitor is N-butyl thiophosphoryl triamide, the phosphorus activator is biochar, the nitrification inhibitor is 2,3,5-trichloropyridine, and the anti-caking agent is liquid paraffin;

[0038] S1. Melt the urea at 130 °C, and then successively add vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax, and nitrification inhibitor and mix evenly to obtain a mixed slurry;

[0039] S2. Granulate the mixed slurry and cool it to 45 °C to obtain the fertilizer;

[0040] S3. Spray the fertilizer with the anti-caking agent to obtain the product.

[0041] Example 3

[0042] A preparation method of a high-activity urea-based compound fertilizer includes the following steps:

[0043] S0. Weigh each material by weight parts: 45 kg of urea, 1.2 kg of vermiculite powder, 22 kg of monoammonium phosphate, 23 kg of potassium sulfate, 13 kg of humic acid, 4 kg of urease inhibitor, 4 kg of phosphorus activator, 3 kg of agricultural selenium fertilizer, 5 kg of zinc sulfate, 2.5 kg of borax, 3 kg of anti-caking agent, and 1.5 kg of nitrification inhibitor. The urease inhibitor is N-butyl thiophosphoryl triamide, the phosphorus activator is biochar, the nitrification inhibitor is 2,3,5-trichloropyridine, and the anti-caking agent is liquid paraffin;

[0044] S1. Melt the urea at 130 °C, and then successively add vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax, and nitrification inhibitor and mix evenly to obtain a mixed slurry;

[0045] S2. Granulate the mixed slurry and cool it to 45 °C to obtain the fertilizer;

[0046] S3. Spray the fertilizer with the anti-caking agent to obtain the product.

[0047] Example 4

[0048] A preparation method of a high-activity urea-based compound fertilizer includes the following steps:

[0049] S0. Weigh each material by weight parts: 45 kg of urea, 1.2 kg of vermiculite powder, 22 kg of monoammonium phosphate, 23 kg of potassium sulfate, 13 kg of humic acid, 4 kg of urease inhibitor, 4 kg of phosphorus activator, 3 kg of agricultural selenium fertilizer, 5 kg of zinc sulfate, 2.5 kg of borax, 3 kg of anti-caking agent and 1.5 kg of nitrification inhibitor. The urease inhibitor is N-n-butyl thiophosphoryl triamide, the phosphorus activator is biochar, the nitrification inhibitor is 2-chloro-6-trichloromethylpyridine, and the anti-caking agent is magnesium stearate;

[0050] S1. Melt the urea at 130 °C, and then sequentially add vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mix them evenly to obtain a mixed slurry;

[0051] S2. Granulate the mixed slurry and cool it to 45 °C to obtain the fertilizer;

[0052] S3. Spray the fertilizer with the anti-caking agent to obtain the product.

[0053] Example 5

[0054] A preparation method of a high-activity urea-based compound fertilizer includes the following steps:

[0055] S0. Weigh each material by weight parts: 45 kg of urea, 1.2 kg of vermiculite powder, 22 kg of monoammonium phosphate, 23 kg of potassium sulfate, 13 kg of humic acid, 4 kg of urease inhibitor, 4 kg of phosphorus activator, 3 kg of agricultural selenium fertilizer, 5 kg of zinc sulfate, 2.5 kg of borax, 3 kg of anti-caking agent and 1.5 kg of nitrification inhibitor. The urease inhibitor is N-n-butyl thiophosphoryl triamide, the phosphorus activator is biochar, the nitrification inhibitor is 2-chloro-6-trichloromethylpyridine, and the anti-caking agent is zinc stearate;

[0056] S1. Melt the urea at 130 °C, and then sequentially add vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mix them evenly to obtain a mixed slurry;

[0057] S2. Granulate the mixed slurry and cool it to 45 °C to obtain the fertilizer;

[0058] S3. Spray the fertilizer with the anti-caking agent to obtain the product.

[0059] Example 6

[0060] A preparation method of a high-activity urea-based compound fertilizer includes the following steps:

[0061] S0. Weigh each material by weight parts: 45 kg of urea, 1.2 kg of vermiculite powder, 22 kg of monoammonium phosphate, 23 kg of potassium sulfate, 13 kg of humic acid, 4 kg of urease inhibitor, 4 kg of phosphorus activator, 3 kg of agricultural selenium fertilizer, 5 kg of zinc sulfate, 2.5 kg of borax, 3 kg of anti-caking agent and 1.5 kg of nitrification inhibitor. The urease inhibitor is N-butyl thiophosphoryl triamide, the phosphorus activator is biochar, the nitrification inhibitor includes dicyandiamide and 3,5,6-trichloro-2-pyridinol, the mass ratio of dicyandiamide to 3,5,6-trichloro-2-pyridinol is 1:1, and the anti-caking agent is zinc stearate;

[0062] S1. Melt the urea at 130 °C, and then successively add vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mix them evenly to obtain a mixed slurry;

[0063] S2. Granulate the mixed slurry and cool it to 45 °C to obtain the fertilizer;

[0064] S3. Spray the fertilizer with the anti-caking agent to obtain the product.

[0065] Example 7

[0066] A preparation method of a high-activity urea-based compound fertilizer, comprising the following steps:

[0067] S0. Weigh each material by weight parts: 45 kg of urea, 1.2 kg of vermiculite powder, 22 kg of monoammonium phosphate, 23 kg of potassium sulfate, 13 kg of humic acid, 4 kg of urease inhibitor, 4 kg of phosphorus activator, 3 kg of agricultural selenium fertilizer, 5 kg of zinc sulfate, 2.5 kg of borax, 3 kg of anti-caking agent and 1.5 kg of nitrification inhibitor. The urease inhibitor is N-butyl thiophosphoryl triamide, the phosphorus activator is biochar, the nitrification inhibitor includes dicyandiamide and 3,5,6-trichloro-2-pyridinol, the mass ratio of dicyandiamide to 3,5,6-trichloro-2-pyridinol is 1:1.5, and the anti-caking agent is zinc stearate;

[0068] S1. Melt the urea at 130 °C, and then successively add vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mix them evenly to obtain a mixed slurry;

[0069] S2. Granulate the mixed slurry and cool it to 45 °C to obtain the fertilizer;

[0070] S3. Spray the fertilizer with the anti-caking agent to obtain the product.

[0071] Example 8

[0072] A preparation method of a high-activity urea-based compound fertilizer, comprising the following steps:

[0073] S0. Weigh each material by weight parts: 45 kg of urea, 1.2 kg of vermiculite powder, 22 kg of monoammonium phosphate, 23 kg of potassium sulfate, 13 kg of humic acid, 4 kg of urease inhibitor, 4 kg of phosphorus activator, 3 kg of agricultural selenium fertilizer, 5 kg of zinc sulfate, 2.5 kg of borax, 3 kg of anti-caking agent and 1.5 kg of nitrification inhibitor. The urease inhibitor is N-butyl thiophosphoryl triamide, the phosphorus activator is biochar, the nitrification inhibitor includes dicyandiamide and 2-chloro-6-(trichloromethyl)pyridine, and the mass ratio of dicyandiamide to 2-chloro-6-(trichloromethyl)pyridine is 1:1.2. The anti-caking agent is zinc stearate;

[0074] S1. Melt the urea at 130 °C, and then successively add vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mix evenly to obtain a mixed slurry;

[0075] S2. Granulate the mixed slurry and cool it to 45 °C to obtain the fertilizer;

[0076] S3. Spray the fertilizer with the anti-caking agent to obtain the product.

[0077] Example 9

[0078] A preparation method of a high-activity urea-based compound fertilizer, comprising the following steps:

[0079] S0. Weigh each material by weight parts: 45 kg of urea, 1.2 kg of vermiculite powder, 22 kg of monoammonium phosphate, 23 kg of potassium sulfate, 13 kg of humic acid, 4 kg of urease inhibitor, 4 kg of phosphorus activator, 3 kg of agricultural selenium fertilizer, 5 kg of zinc sulfate, 2.5 kg of borax, 3 kg of anti-caking agent and 1.5 kg of nitrification inhibitor. The urease inhibitor is yucca extract, the phosphorus activator is biochar, the nitrification inhibitor includes dicyandiamide and 2-chloro-6-(trichloromethyl)pyridine, and the mass ratio of dicyandiamide to 2-chloro-6-(trichloromethyl)pyridine is 1:1. The anti-caking agent is zinc stearate;

[0080] S1. Melt the urea at 130 °C, and then successively add vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mix evenly to obtain a mixed slurry;

[0081] S2. Granulate the mixed slurry and cool it to 45 °C to obtain the fertilizer;

[0082] S3. Spray the fertilizer with the anti-caking agent to obtain the product.

[0083] Example 10

[0084] A preparation method of a high-activity urea-based compound fertilizer, comprising the following steps:

[0085] S0. Weigh each material by weight parts: 45 kg of urea, 1.2 kg of vermiculite powder, 22 kg of monoammonium phosphate, 23 kg of potassium sulfate, 13 kg of humic acid, 4 kg of urease inhibitor, 4 kg of phosphorus activator, 3 kg of agricultural selenium fertilizer, 5 kg of zinc sulfate, 2.5 kg of borax, 3 kg of anti-caking agent and 1.5 kg of nitrification inhibitor. The urease inhibitor is yucca extract, the phosphorus activator is biochar, the nitrification inhibitor includes dicyandiamide and 3,4,4-trichloromethylpyridine, and the mass ratio of dicyandiamide to 3,4,4-trichloromethylpyridine is 1:1. The anti-caking agent is zinc stearate;

[0086] S1. Dissolve the humic acid in water to obtain a mixture, then mix the urease inhibitor with the mixture and dry to obtain a prefabricated product; Melt the urea at 130 °C, and then sequentially add monoammonium phosphate, potassium sulfate, the prefabricated product, the phosphorus activator, the agricultural selenium fertilizer, zinc sulfate, borax, and the nitrification inhibitor and mix evenly to obtain a mixed slurry;

[0087] S2. Granulate the mixed slurry and cool it to 45 °C to obtain the fertilizer;

[0088] S3. Spray the fertilizer with the anti-caking agent to obtain the product.

[0089] Example 11

[0090] A preparation method of a high-activity urea-based compound fertilizer, comprising the following steps:

[0091] S0. Weigh each material by weight parts: 45 kg of urea, 1.2 kg of vermiculite powder, 22 kg of monoammonium phosphate, 23 kg of potassium sulfate, 13 kg of humic acid, 4 kg of urease inhibitor, 4 kg of phosphorus activator, 3 kg of agricultural selenium fertilizer, 5 kg of zinc sulfate, 2.5 kg of borax, 3 kg of anti-caking agent and 1.5 kg of nitrification inhibitor. The urease inhibitor is yucca extract, the phosphorus activator is biochar, the nitrification inhibitor includes dicyandiamide and 3,4,4-trichloromethylpyridine, and the mass ratio of dicyandiamide to 3,4,4-trichloromethylpyridine is 1:1. The anti-caking agent is zinc stearate;

[0092] S1. Take 0.6 kg of vermiculite powder and mix it evenly with the urease inhibitor to obtain a first mixture, and dissolve the humic acid in water to obtain a second mixture. Then mix the first mixture and the second mixture evenly and dry to obtain a prefabricated product; Melt the urea at 130 °C, and then sequentially add the remaining vermiculite powder, monoammonium phosphate, potassium sulfate, the prefabricated product, the phosphorus activator, the agricultural selenium fertilizer, zinc sulfate, borax, and the nitrification inhibitor and mix evenly to obtain a mixed slurry;

[0093] S2. Granulate the mixed slurry and cool it to 45 °C to obtain the fertilizer;

[0094] S3. Spray the fertilizer with the anti-caking agent to obtain the product.

[0095] Example 12

[0096] A preparation method of a highly active urea-based compound fertilizer, comprising the following steps:

[0097] S0. Weigh each material according to parts by weight: 45 kg of urea, 1.2 kg of vermiculite powder, 22 kg of monoammonium phosphate, 23 kg of potassium sulfate, 13 kg of humic acid, 4 kg of urease inhibitor, 4 kg of phosphorus activator, 3 kg of agricultural selenium fertilizer, 5 kg of zinc sulfate, 2.5 kg of borax, 3 kg of anti-caking agent, and 1.5 kg of nitrification inhibitor. The urease inhibitor is yucca extract, the phosphorus activator is biochar, the nitrification inhibitor includes dicyandiamide and 2-chloro-6-(trichloromethyl)pyridine, the mass ratio of dicyandiamide to 2-chloro-6-(trichloromethyl)pyridine is 1:1, and the anti-caking agent is zinc stearate;

[0098] S1. Take 0.6 kg of vermiculite powder and mix it evenly with the urease inhibitor to obtain a first mixture; melt the urea at 130 °C, and then sequentially add the remaining vermiculite powder, humic acid, monoammonium phosphate, potassium sulfate, the first mixture, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax, and nitrification inhibitor and mix evenly to obtain a mixed slurry;

[0099] S2. Granulate the mixed slurry and cool it to 45 °C to obtain the fertilizer;

[0100] S3. Spray the fertilizer with the anti-caking agent to obtain the product.

[0101] Comparative example

[0102] Comparative example 1

[0103] A preparation method of a highly active urea-based compound fertilizer, comprising the following steps:

[0104] S0. Weigh each material according to parts by weight: 43 kg of urea, 1 kg of vermiculite powder, 20 kg of monoammonium phosphate, 20 kg of potassium sulfate, 10 kg of humic acid, 3 kg of urease inhibitor, 3 kg of phosphorus activator, 0.5 kg of agricultural selenium fertilizer, 0.5 kg of zinc sulfate, 0.5 kg of borax, and 1 kg of nitrification inhibitor. The urease inhibitor is N-butyl thiophosphoryl triamide, the phosphorus activator is biochar, the nitrification inhibitor is 2-chloro-6-(trichloromethyl)pyridine, and the anti-caking agent is liquid paraffin;

[0105] S1. Melt the urea at 130 °C, and then sequentially add vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax, and nitrification inhibitor and mix evenly to obtain a mixed slurry;

[0106] S2. Granulate the mixed slurry and cool it to 45 °C to obtain the fertilizer.

[0107] Comparative example 2

[0108] A preparation method of a highly active urea-based compound fertilizer, comprising the following steps:

[0109] S0. Weigh each material according to parts by weight: 45 kg of urea, 22 kg of monoammonium phosphate, 23 kg of potassium sulfate, 13 kg of humic acid, 4 kg of urease inhibitor, 4 kg of phosphorus activator, 3 kg of agricultural selenium fertilizer, 5 kg of zinc sulfate, 2.5 kg of borax, 3 kg of anti-caking agent, and 1.5 kg of nitrification inhibitor. The urease inhibitor is yucca extract, the phosphorus activator is biochar, the nitrification inhibitor includes dicyandiamide and 3,4-dichloromethylpyridine, and the mass ratio of dicyandiamide to 3,4-dichloromethylpyridine is 1:1. The anti-caking agent is zinc stearate;

[0110] S1. Melt urea at 130 °C, and then successively add monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax, and nitrification inhibitor and mix evenly to obtain a mixed slurry;

[0111] S2. Granulate the mixed slurry and cool it to 45 °C to obtain the fertilizer;

[0112] S3. Spray the fertilizer with the anti-caking agent to obtain the product.

[0113] Performance detection test

[0114] Detection method

[0115] Caking test: Conduct caking experiments on the urea-based compound fertilizer samples prepared in Examples 1 to 10 and Comparative Example 1 respectively. The specific operation is as follows: Put the treated compound fertilizer samples into a high and low temperature and humidity test chamber with a sample packaging bag, control the temperature of the test chamber at 25 ± 5 °C, and the relative humidity at 70-75%. Turn off the power at night to reach room temperature and indoor environmental humidity; Take out the samples after 7 days, freely drop the samples from a height of 1 m once on each of the front and back sides, unpack and sieve with a standard sieve, and check the anti-caking effect through the caking rate. Among them, the caking rate is calculated according to the following formula: Caking rate = mass of caked compound fertilizer / mass of compound fertilizer * 100%.

[0116] Urease activity: Take 5 g of the compound fertilizers prepared in Examples 1-10 and Comparative Examples 1-2 and add them to 100 g of soil and mix evenly, place them in a 200 ml triangular flask, and moisten with water. Incubate at a constant temperature of 37 °C for 72 h, and measure the soil urease activity. The soil physical and chemical properties are: available nitrogen content 20.4 mg / kg, available phosphorus content 18.14 mg / kg, pH 7.34, available potassium content 192 mg / kg, and organic matter content 15.4 g / kg.

[0117] Nitrate nitrogen content: Take 5 g of the compound fertilizers prepared in Examples 1 - 10 and Comparative Examples 1 - 2, add them to 100 g of soil, mix well, and place them in a 200 - ml Erlenmeyer flask. Moisten with water. Incubate at a constant temperature of 37 °C for 72 h, and determine the nitrate nitrogen content in the soil according to GB / T 3597 - 2002 "Determination of nitrate nitrogen content in fertilizers - Nitrogen reagent gravimetric method". The physical and chemical properties of the soil are as follows: alkaline hydrolyzable nitrogen content is 20.4 mg / kg, available phosphorus content is 18.14 mg / kg, pH is 7.34, available potassium content is 192 mg / kg, and organic matter content is 15.4 g / kg.

[0118] Biuret content: According to GB / T 22924 - 2024, the biuret content in the compound fertilizers prepared in Examples 1 - 10 and Comparative Example 1 was detected by high - performance liquid chromatography.

[0119] Table 1

[0120]

[0121] Combined with Example 1 and Comparative Example 1 and Table 1, it can be seen that the anti - caking agent added in this application can significantly reduce the caking rate of the compound fertilizer;

[0122] Combined with Examples 3 - 4 and Table 1, it can be seen that in Example 4, when the anti - caking agent is stearate, the crushing resistance value of the compound fertilizer is significantly increased. The reason is that stearate can enter the voids of the fertilizer particles, thereby increasing the crushing resistance value of the compound fertilizer;

[0123] Combined with Examples 4 - 5 and Table 1, it can be seen that compared with Example 4, in Example 5, when the stearate is zinc stearate, the nitrate nitrogen content is significantly reduced. The reason is that the zinc ions in zinc stearate act as a bridge when dicyandiamide binds to the ammonia monooxygenase of nitrifying bacteria, and form a coordination bond with specific amino acid residues of ammonia monooxygenase, thereby promoting the binding of dicyandiamide to ammonia monooxygenase, and further enhancing the nitrification inhibition effect of the nitrification inhibitor;

[0124] Combined with Examples 5 - 6 and Table 1, it can be seen that when dicyandiamide and nitrapyrin are used in combination in Example 6, the nitrate nitrogen content is significantly reduced;

[0125] Combined with Examples 9 - 10 and Table 1, it can be seen that in Example 10, when humic acid and yucca extract are premixed, a protective film is formed on the surface of yucca extract by humic acid, reducing the contact between ultraviolet light and yucca extract, so that ultraviolet light is not easy to decompose yucca extract, thereby improving the overall stability of the fertilizer, and further reducing the urease activity.

[0126] Combined with Examples 10 to 12 and Table 1, it can be seen that the premixing of vermiculite powder and yucca extract in Example 12 reduces the urease activity. The reason is that: the premixing of vermiculite powder and yucca extract enables vermiculite powder to adsorb yucca extract, so that after the fertilizer containing vermiculite powder and yucca extract enters the soil, vermiculite powder can absorb heat during the day and release heat at night to reduce the temperature change of the soil, thereby reducing the influence of soil temperature change on the activity of yucca extract; in addition, the premixing of humic acid with vermiculite powder and yucca extract in Example 11 enables the sticky humic acid to combine the vermiculite powder and yucca extract entering the soil more tightly, so as to further reduce the influence of soil temperature change on the activity of yucca extract.

[0127] This specific embodiment is only an interpretation of the present application, and it does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A preparation method of a highly active urea-based compound fertilizer, characterized in that, It includes the following steps: S1. Take a part of vermiculite powder and mix it evenly with the urease inhibitor to obtain the first mixture, dissolve humic acid in water to obtain the second mixture, then mix the first mixture and the second mixture evenly and dry to obtain the prefabricated product; melt urea, and then sequentially add the remaining vermiculite powder, monoammonium phosphate, potassium sulfate, prefabricated product, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax, and nitrification inhibitor and mix evenly to obtain the mixed slurry; S2. Granulate the mixed slurry and cool to obtain the fertilizer; S3. Spray the fertilizer with the anti-caking agent to obtain the product; The high-activity urea-based compound fertilizer includes the following components: urea, vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax, and nitrification inhibitor; the mass parts of each component in the high-activity urea-based compound fertilizer are as follows: 43-48 parts of urea, 1-1.5 parts of vermiculite powder, 20-25 parts of monoammonium phosphate, 20-26 parts of potassium sulfate, 10-15 parts of humic acid, 3-5 parts of urease inhibitor, 3-5 parts of phosphorus activator, 0.5-5 parts of agricultural selenium fertilizer, 0.5-8 parts of zinc sulfate, 0.5-4 parts of borax, 1-2 parts of nitrification inhibitor, and 1-3 parts of anti-caking agent; the anti-caking agent is zinc stearate; the nitrification inhibitor includes dicyandiamide and 3,4,4-trichloromethylpyridine, and the mass part ratio of dicyandiamide to 3,4,4-trichloromethylpyridine is 1:(1-1.5); the urease inhibitor is yucca extract.

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