Preparation method of high-activity urea-based compound fertilizer

Abstract

The invention relates to the field of compound fertilizer production, and particularly discloses a high-activity urea-based compound fertilizer preparation method, which specifically comprises: 1, melting urea, and uniformly mixing with other components to obtain a mixed slurry; 2, granulating the mixed slurry, and cooling to obtain a fertilizer; step 3, spraying the fertilizer with an anti-blocking agent to obtain a product; the high-activity urea-based compound fertilizer comprises the following components: urea, vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, a urease inhibitor, a phosphorus activator, an agricultural selenium fertilizer, zinc sulfate, borax and a nitrification inhibitor. Due to the addition of the anti-blocking agent, the compound fertilizer is not easy to block due to moisture absorption, so that the purpose that the urea-based compound fertilizer is not easy to harden is achieved.

Description

Technical Field

[0001] The present invention relates to the field of compound fertilizer production, and more specifically, to a method for preparing 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.

[0003] In urea-based compound fertilizers, since urea is a linear straight-chain crystal, it is easy to form regular hexagonal crystals. These crystal lattices have many holes inside, which makes the urea crystals highly absorbent due to capillary adsorption. As a result, the urea surface easily absorbs moisture and becomes hardened, resulting in the hardening of urea-based compound fertilizers. Summary of the invention

[0004] In order to prevent urea-based compound fertilizer from becoming hardened, the present application provides a method for preparing a high-activity urea-based compound fertilizer.

[0005] The present application provides a method for preparing a highly active urea-based compound fertilizer, which adopts the following technical scheme: A method for preparing a highly active urea-based compound fertilizer comprises the following steps: S1, melting urea, and then mixing it evenly with other components to obtain a mixed slurry; S2, granulating the mixed slurry and cooling it to obtain fertilizer; S3. Spraying the fertilizer with an anti-caking agent to obtain a product; the high-activity urea-based compound fertilizer comprises 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.

[0006] By adopting the above technical scheme, trace elements such as boron and zinc have an important regulatory effect on the growth and development of plants, can improve the activity of enzymes in plants, promote photosynthesis and metabolism of plants, and thus enhance the overall activity of urea-based compound fertilizers; humic acid has strong chelating ability and ion exchange ability, can form stable chelates with nutrients in fertilizers, improve the effectiveness of nutrients and further improve the activity of nutrients in fertilizers, and at the same time, humic acid can also promote the growth and development of plant roots and enhance the ability of plants to absorb nutrients; monoammonium phosphate has high water solubility and nutrient effectiveness, and potassium sulfate is used as a potassium source, which can ensure the supply of potassium elements 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, and fix them in the lattice structure of vermiculite, reduce nutrient volatilization and leaching losses, improve the nutrient retention capacity of fertilizers, and achieve a slow release effect; the addition of anti-caking agent makes it difficult for compound fertilizers to clump due to moisture absorption, thereby achieving the purpose of making urea-based compound fertilizers less likely to form hardening phenomena.

[0007] Preferably, the mass parts of the material components of the highly active 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.

[0008] Preferably, the anti-caking agent is stearate.

[0009] By adopting the above technical solution, stearate has hydrophobicity and can form a thin hydrophobic film on the surface of fertilizer particles. This film can prevent the fertilizer particles from absorbing moisture in the air and reduce the agglomeration caused by moisture absorption, so as to keep the fertilizer particles loose. In addition, stearate can combine with nutrients such as nitrogen, phosphorus, and potassium in the fertilizer to form a relatively stable structure, so that after the fertilizer is applied to the soil, the moisture and microorganisms in the soil need to first destroy the protective film formed by stearate or the binding structure with the fertilizer before the nutrients in the fertilizer can be released, thereby extending the release time of the nutrients in the fertilizer. In the fertilizer production process, part of the stearate is adsorbed on the surface of the fertilizer particles to achieve a water-blocking effect, and the other part will be filled into the tiny gaps in the fertilizer particles, making the fertilizer particle structure more compact, thereby enhancing the compressive strength of the fertilizer particles and reducing the particle breakage caused by the fertilizer during transportation and loading and unloading.

[0010] Preferably, the stearate is zinc stearate.

[0011] By adopting the above technical scheme, zinc stearate can interact with soil particles, promote the agglomeration of soil particles through physical adsorption, electrostatic action, etc., improve the agglomeration and aeration of the soil, which is beneficial to the growth and respiration of plant roots and creates a good soil environment for plant growth.

[0012] Preferably, the nitrification inhibitor comprises dicyandiamide and trichloromethylpyridine, and the mass ratio of the dicyandiamide to trichloromethylpyridine is 1:(1-1.5).

[0013] By adopting the above technical scheme, in the soil, nitrogen fertilizers such as urea will undergo a series of conversion processes after being applied, among which 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 converted into nitrogen and other gases through denitrification under specific conditions (such as good soil aeration) and volatilized and lost. Nitrification inhibitors 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, thereby having a The invention discloses a novel novel novel novel nitrifying agent, which has a certain affinity and can specifically bind to the active site, thereby blocking the process of converting ammonia nitrogen into nitrite; trichloromethylpyridine can chelate Cu on the active site of ammonia monooxygenase of nitrifying bacteria, affecting the activity of ammonia monooxygenase. When used in combination with dicyandiamide, it can inhibit nitrification from different angles, thereby indirectly improving the binding efficiency of dicyandiamide and ammonia monooxygenase; in addition, when dicyandiamide acts, the zinc ions in zinc stearate can act as a bridge to form a coordination bond with the specific amino acid residues of ammonia monooxygenase to promote the binding of dicyandiamide and ammonia monooxygenase, thereby improving the effect of nitrification inhibitor; in addition, in this process, the zinc ions of zinc stearate are consumed to reduce the catalytic effect of zinc stearate on the urea condensation reaction, thereby reducing the amount of biuret.

[0014] Preferably, the urease inhibitor is yucca extract.

[0015] By adopting the above technical solution, urea is a commonly used high-concentration nitrogen fertilizer, which 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 mixed with urea, it can effectively slow down the hydrolysis rate of urea, reduce the volatilization of ammonia, 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 effect of nitrogen fertilizer.

[0016] Preferably, in S1, humic acid is dissolved in water to obtain a mixture, and then the urease inhibitor is mixed with the mixture and then dried to obtain a preform; urea is melted, and then vermiculite powder, monoammonium phosphate, potassium sulfate, the preform, a phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax, and a nitrification inhibitor are added in sequence and mixed evenly to obtain a mixed slurry.

[0017] By adopting the above technical solution, humic acid and yucca extract are pre-mixed, so that humic acid forms a protective film on the surface of yucca extract, reducing the contact between ultraviolet rays and yucca extract, so that ultraviolet rays are not easy to decompose the yucca extract, thereby improving the overall stability of the fertilizer.

[0018] Preferably, in S1, a portion of the vermiculite powder and the urease inhibitor are mixed to obtain a first mixture, and humic acid is dissolved in water to obtain a second mixture, and then the first mixture and the second mixture are mixed and dried to obtain a preform; urea is melted, and then the remaining vermiculite powder, monoammonium phosphate, potassium sulfate, the preform, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax, and nitrification inhibitor are added in sequence and mixed evenly to obtain a mixed slurry.

[0019] By adopting the above technical solution, the vermiculite powder and the urease inhibitor are pre-mixed, so that part of the urease inhibitor is attached to the surface of the vermiculite powder. Since the vermiculite powder can absorb heat during the day and begin to release heat at night, the temperature change of the soil is small, thereby reducing the impact of soil temperature changes on the activity of the urease inhibitor.

[0020] In summary, this application has the following beneficial effects: 1. Boron, zinc and other trace elements have an important regulatory effect on the growth and development of plants, can improve the activity of enzymes in plants, promote photosynthesis and metabolism of plants, and thus enhance the overall activity of urea-based compound fertilizers; humic acid has strong chelating and ion exchange capabilities, can form stable chelates with nutrients in fertilizers, improve the effectiveness of nutrients and further improve the activity of nutrients in fertilizers, and at the same time, humic acid can also promote the growth and development of plant roots and enhance the ability of plants to absorb nutrients; 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 to plants and has high activity; in addition, vermiculite powder has strong ion exchange and adsorption capabilities, can adsorb nutrients such as ammonium ions, and fix them in the lattice structure of vermiculite, reduce nutrient volatilization and leaching losses, improve the nutrient retention capacity of fertilizers, and achieve a slow release effect; the addition of anti-caking agent makes it difficult for compound fertilizers to clump due to moisture absorption, thereby achieving the purpose of making urea-based compound fertilizers less likely to become hardened.

[0021] 2. The premixing of humic acid and yucca extract allows humic acid to form a protective film on the surface of the yucca extract, reducing the contact between ultraviolet rays and the yucca extract, making it difficult for ultraviolet rays to decompose the yucca extract, thereby improving the overall stability of the fertilizer. DETAILED DESCRIPTION

[0022] The present application is further described in detail below in conjunction with the examples and comparative examples. The raw materials used in this application are all commercially available, wherein humic acid is purchased from Jinan Jiayang Chemical Co., Ltd., agricultural selenium fertilizer is purchased from Qingdao Pengyang Bioengineering Co., Ltd., borax is purchased from Chengdu Zhongpeng Chemical Co., Ltd., N-n-butylthiophosphoric acid triamide is purchased from Shandong West Asia Chemical Co., Ltd., biochar is purchased from Henan Li Ze Environmental Protection Technology Co., Ltd., trichloromethylpyridine is purchased from 2-chloro-6-trichloromethylpyridine of Wuhan Smack 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.

[0023] Example Example 1 A method for preparing a highly active urea-based compound fertilizer comprises the following steps: S0, weigh each material according to weight, 43kg urea, 1kg vermiculite powder, 20kg monoammonium phosphate, 20kg potassium sulfate, 10kg humic acid, 3kg urease inhibitor, 3kg phosphorus activator, 0.5kg agricultural selenium fertilizer, 0.5kg zinc sulfate, 0.5kg borax, 0.5kg anti-caking agent and 1kg nitrification inhibitor, the urease inhibitor is N-n-butylthiophosphoric acid triamide, the phosphorus activator is biochar, the nitrification inhibitor is trichloromethylpyridine, and the anti-caking agent is liquid paraffin; S1. Melting urea at 130° C., then sequentially adding vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mixing evenly to obtain a mixed slurry; S2, granulating the mixed slurry and cooling it to 45° C. to obtain a fertilizer; S3, spraying the fertilizer with an anti-caking agent to obtain a product.

[0024] Example 2 A method for preparing a highly active urea-based compound fertilizer comprises the following steps: S0, weigh each material according to weight, 48kg urea, 1.5kg vermiculite powder, 25kg monoammonium phosphate, 26kg potassium sulfate, 15kg humic acid, 5kg urease inhibitor, 5kg phosphorus activator, 5kg agricultural selenium fertilizer, 8kg zinc sulfate, 4kg borax, 4kg anti-caking agent and 2kg nitrification inhibitor, the urease inhibitor is N-n-butyl thiophosphoric acid triamide, the phosphorus activator is biochar, the nitrification inhibitor is trichloromethylpyridine, and the anti-caking agent is liquid paraffin; S1. Melting urea at 130° C., then sequentially adding vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mixing evenly to obtain a mixed slurry; S2, granulating the mixed slurry and cooling it to 45° C. to obtain a fertilizer; S3, spraying the fertilizer with an anti-caking agent to obtain a product.

[0025] Example 3 A method for preparing a highly active urea-based compound fertilizer comprises the following steps: S0, weigh each material according to weight, 45kg of urea, 1.2kg of vermiculite powder, 22kg of monoammonium phosphate, 23kg of potassium sulfate, 13kg of humic acid, 4kg of urease inhibitor, 4kg of phosphorus activator, 3kg of agricultural selenium fertilizer, 5kg of zinc sulfate, 2.5kg of borax, 3kg of anti-caking agent and 1.5kg of nitrification inhibitor, the urease inhibitor is N-n-butylthiophosphoric acid triamide, the phosphorus activator is biochar, the nitrification inhibitor is trichloromethylpyridine, and the anti-caking agent is liquid paraffin; S1. Melting urea at 130° C., then sequentially adding vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mixing evenly to obtain a mixed slurry; S2, granulating the mixed slurry and cooling it to 45° C. to obtain a fertilizer; S3, spraying the fertilizer with an anti-caking agent to obtain a product.

[0026] Example 4 A method for preparing a highly active urea-based compound fertilizer comprises the following steps: S0, weigh each material according to weight, 45kg of urea, 1.2kg of vermiculite powder, 22kg of monoammonium phosphate, 23kg of potassium sulfate, 13kg of humic acid, 4kg of urease inhibitor, 4kg of phosphorus activator, 3kg of agricultural selenium fertilizer, 5kg of zinc sulfate, 2.5kg of borax, 3kg of anti-caking agent and 1.5kg of nitrification inhibitor, the urease inhibitor is N-n-butylthiophosphoric acid triamide, the phosphorus activator is biochar, the nitrification inhibitor is trichloromethylpyridine, and the anti-caking agent is magnesium stearate; S1. Melting urea at 130° C., then sequentially adding vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mixing evenly to obtain a mixed slurry; S2, granulating the mixed slurry and cooling it to 45° C. to obtain a fertilizer; S3, spraying the fertilizer with an anti-caking agent to obtain a product.

[0027] Example 5 A method for preparing a highly active urea-based compound fertilizer comprises the following steps: S0, weigh each material according to weight, 45kg of urea, 1.2kg of vermiculite powder, 22kg of monoammonium phosphate, 23kg of potassium sulfate, 13kg of humic acid, 4kg of urease inhibitor, 4kg of phosphorus activator, 3kg of agricultural selenium fertilizer, 5kg of zinc sulfate, 2.5kg of borax, 3kg of anti-caking agent and 1.5kg of nitrification inhibitor, the urease inhibitor is N-n-butylthiophosphoric acid triamide, the phosphorus activator is biochar, the nitrification inhibitor is trichloromethylpyridine, and the anti-caking agent is zinc stearate; S1. Melting urea at 130° C., then sequentially adding vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mixing evenly to obtain a mixed slurry; S2, granulating the mixed slurry and cooling it to 45° C. to obtain a fertilizer; S3, spraying the fertilizer with an anti-caking agent to obtain a product.

[0028] Example 6 A method for preparing a highly active urea-based compound fertilizer comprises the following steps: S0, weigh each material according to weight, 45kg of urea, 1.2kg of vermiculite powder, 22kg of monoammonium phosphate, 23kg of potassium sulfate, 13kg of humic acid, 4kg of urease inhibitor, 4kg of phosphorus activator, 3kg of agricultural selenium fertilizer, 5kg of zinc sulfate, 2.5kg of borax, 3kg of anti-caking agent and 1.5kg of nitrification inhibitor, the urease inhibitor is N-n-butylthiophosphoric acid triamide, the phosphorus activator is biochar, the nitrification inhibitor includes dicyandiamide and trichloromethylpyridine, the mass ratio of dicyandiamide and trichloromethylpyridine is 1:1, and the anti-caking agent is zinc stearate; S1. Melting urea at 130° C., then sequentially adding vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mixing evenly to obtain a mixed slurry; S2, granulating the mixed slurry and cooling it to 45° C. to obtain a fertilizer; S3, spraying the fertilizer with an anti-caking agent to obtain a product.

[0029] Example 7 A method for preparing a highly active urea-based compound fertilizer comprises the following steps: S0, weigh each material according to weight, 45kg of urea, 1.2kg of vermiculite powder, 22kg of monoammonium phosphate, 23kg of potassium sulfate, 13kg of humic acid, 4kg of urease inhibitor, 4kg of phosphorus activator, 3kg of agricultural selenium fertilizer, 5kg of zinc sulfate, 2.5kg of borax, 3kg of anti-caking agent and 1.5kg of nitrification inhibitor, the urease inhibitor is N-n-butylthiophosphoric acid triamide, the phosphorus activator is biochar, the nitrification inhibitor includes dicyandiamide and trichloromethylpyridine, the mass ratio of dicyandiamide and trichloromethylpyridine is 1:1.5, and the anti-caking agent is zinc stearate; S1. Melting urea at 130° C., then sequentially adding vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mixing evenly to obtain a mixed slurry; S2, granulating the mixed slurry and cooling it to 45° C. to obtain a fertilizer; S3, spraying the fertilizer with an anti-caking agent to obtain a product.

[0030] Example 8 A method for preparing a highly active urea-based compound fertilizer comprises the following steps: S0, weigh each material according to weight, urea 45kg, vermiculite powder 1.2kg, monoammonium phosphate 22kg, potassium sulfate 23kg, humic acid 13kg, urease inhibitor 4kg, phosphorus activator 4kg, agricultural selenium fertilizer 3kg, zinc sulfate 5kg, borax 2.5kg, anti-caking agent 3kg and nitrification inhibitor 1.5kg, urease inhibitor is N-n-butyl thiophosphoric acid triamide, phosphorus activator is biochar, nitrification inhibitor includes dicyandiamide and trichloromethyl pyridine, the mass ratio of dicyandiamide and trichloromethyl pyridine is 1:1.2, and anti-caking agent is zinc stearate; S1. Melting urea at 130° C., then sequentially adding vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mixing evenly to obtain a mixed slurry; S2, granulating the mixed slurry and cooling it to 45° C. to obtain a fertilizer; S3, spraying the fertilizer with an anti-caking agent to obtain a product.

[0031] Example 9 A method for preparing a highly active urea-based compound fertilizer comprises the following steps: S0, weighing each material according to weight, 45kg of urea, 1.2kg of vermiculite powder, 22kg of monoammonium phosphate, 23kg of potassium sulfate, 13kg of humic acid, 4kg of urease inhibitor, 4kg of phosphorus activator, 3kg of agricultural selenium fertilizer, 5kg of zinc sulfate, 2.5kg of borax, 3kg of anti-caking agent and 1.5kg of nitrification inhibitor, the urease inhibitor is yucca extract, the phosphorus activator is biochar, the nitrification inhibitor includes dicyandiamide and trichloromethylpyridine, the mass ratio of dicyandiamide to trichloromethylpyridine is 1:1, and the anti-caking agent is zinc stearate; S1. Melting urea at 130° C., then sequentially adding vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mixing evenly to obtain a mixed slurry; S2, granulating the mixed slurry and cooling it to 45° C. to obtain a fertilizer; S3, spraying the fertilizer with an anti-caking agent to obtain a product.

[0032] Example 10 A method for preparing a highly active urea-based compound fertilizer comprises the following steps: S0, weighing each material according to weight, 45kg of urea, 1.2kg of vermiculite powder, 22kg of monoammonium phosphate, 23kg of potassium sulfate, 13kg of humic acid, 4kg of urease inhibitor, 4kg of phosphorus activator, 3kg of agricultural selenium fertilizer, 5kg of zinc sulfate, 2.5kg of borax, 3kg of anti-caking agent and 1.5kg of nitrification inhibitor, the urease inhibitor is yucca extract, the phosphorus activator is biochar, the nitrification inhibitor includes dicyandiamide and trichloromethylpyridine, the mass ratio of dicyandiamide to trichloromethylpyridine is 1:1, and the anti-caking agent is zinc stearate; S1. Dissolving humic acid in water to obtain a mixture, then mixing the urease inhibitor with the mixture and drying to obtain a preform; melting urea at 130° C., then sequentially adding monoammonium phosphate, potassium sulfate, the preform, a phosphorus activator, an agricultural selenium fertilizer, zinc sulfate, borax, and a nitrification inhibitor and mixing them evenly to obtain a mixed slurry; S2, granulating the mixed slurry and cooling it to 45° C. to obtain a fertilizer; S3, spraying the fertilizer with an anti-caking agent to obtain a product.

[0033] Embodiment 11 A method for preparing a highly active urea-based compound fertilizer comprises the following steps: S0, weighing each material according to weight, 45kg of urea, 1.2kg of vermiculite powder, 22kg of monoammonium phosphate, 23kg of potassium sulfate, 13kg of humic acid, 4kg of urease inhibitor, 4kg of phosphorus activator, 3kg of agricultural selenium fertilizer, 5kg of zinc sulfate, 2.5kg of borax, 3kg of anti-caking agent and 1.5kg of nitrification inhibitor, the urease inhibitor is yucca extract, the phosphorus activator is biochar, the nitrification inhibitor includes dicyandiamide and trichloromethylpyridine, the mass ratio of dicyandiamide to trichloromethylpyridine is 1:1, and the anti-caking agent is zinc stearate; S1, taking 0.6 kg of vermiculite powder and urease inhibitor and mixing them to obtain a first mixture, and dissolving humic acid in water to obtain a second mixture, and then mixing the first mixture and the second mixture and drying them to obtain a preform; melting urea at 130° C., and then sequentially adding the remaining vermiculite powder, monoammonium phosphate, potassium sulfate, the preform, a phosphorus activator, an agricultural selenium fertilizer, zinc sulfate, borax, and a nitrification inhibitor and mixing them evenly to obtain a mixed slurry; S2, granulating the mixed slurry and cooling it to 45° C. to obtain a fertilizer; S3, spraying the fertilizer with an anti-caking agent to obtain a product.

[0034] Example 12 A method for preparing a highly active urea-based compound fertilizer comprises the following steps: S0, weighing each material according to weight, 45kg of urea, 1.2kg of vermiculite powder, 22kg of monoammonium phosphate, 23kg of potassium sulfate, 13kg of humic acid, 4kg of urease inhibitor, 4kg of phosphorus activator, 3kg of agricultural selenium fertilizer, 5kg of zinc sulfate, 2.5kg of borax, 3kg of anti-caking agent and 1.5kg of nitrification inhibitor, the urease inhibitor is yucca extract, the phosphorus activator is biochar, the nitrification inhibitor includes dicyandiamide and trichloromethylpyridine, the mass ratio of dicyandiamide to trichloromethylpyridine is 1:1, and the anti-caking agent is zinc stearate; S1, taking 0.6 kg of vermiculite powder and urease inhibitor and mixing them to obtain a first mixture; melting urea at 130° C., and then sequentially adding 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 mixing them evenly to obtain a mixed slurry; S2, granulating the mixed slurry and cooling it to 45° C. to obtain a fertilizer; S3, spraying the fertilizer with an anti-caking agent to obtain a product.

[0035] Comparative Example Comparative Example 1 A method for preparing a highly active urea-based compound fertilizer comprises the following steps: S0, weigh each material according to weight, 43kg urea, 1kg vermiculite powder, 20kg monoammonium phosphate, 20kg potassium sulfate, 10kg humic acid, 3kg urease inhibitor, 3kg phosphorus activator, 0.5kg agricultural selenium fertilizer, 0.5kg zinc sulfate, 0.5kg borax and 1kg nitrification inhibitor, the urease inhibitor is N-n-butylthiophosphoric acid triamide, the phosphorus activator is biochar, the nitrification inhibitor is trichloromethylpyridine, and the anti-caking agent is liquid paraffin; S1. Melting urea at 130° C., then sequentially adding vermiculite powder, monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mixing evenly to obtain a mixed slurry; S2. Granulate the mixed slurry and cool it to 45° C. to obtain a fertilizer.

[0036] Comparative Example 2 A method for preparing a highly active urea-based compound fertilizer comprises the following steps: S0, weighing each material according to weight, 45kg of urea, 22kg of monoammonium phosphate, 23kg of potassium sulfate, 13kg of humic acid, 4kg of urease inhibitor, 4kg of phosphorus activator, 3kg of agricultural selenium fertilizer, 5kg of zinc sulfate, 2.5kg of borax, 3kg of anti-caking agent and 1.5kg of nitrification inhibitor, the urease inhibitor is yucca extract, the phosphorus activator is biochar, the nitrification inhibitor includes dicyandiamide and trichloromethylpyridine, the mass ratio of dicyandiamide to trichloromethylpyridine is 1:1, and the anti-caking agent is zinc stearate; S1. Melting urea at 130° C., then sequentially adding monoammonium phosphate, potassium sulfate, humic acid, urease inhibitor, phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax and nitrification inhibitor and mixing evenly to obtain a mixed slurry; S2, granulating the mixed slurry and cooling it to 45° C. to obtain a fertilizer; S3, spraying the fertilizer with an anti-caking agent to obtain a product.

[0037] Performance testing Detection Methods Caking test: Caking tests were carried out on the urea-based compound fertilizer samples prepared in Examples 1 to 10 and Comparative Example 1, respectively. The specific operations were as follows: the treated compound fertilizer samples were placed in a high and low temperature humidity test chamber with sample packaging bags, the test chamber temperature was controlled to be 25±5°C, the relative humidity was 70-75%, and the power was turned off at night to room temperature and indoor ambient humidity; the samples were taken out after 7 days, and the samples were freely dropped from a height of 1 m on both sides once, and after unpacking, they were sieved with a standard sieve, and the anti-caking effect was tested by the caking rate, wherein the caking rate was calculated according to the following formula: caking rate = mass of caking compound fertilizer / mass of compound fertilizer * 100%.

[0038] Urease activity: 5 g of the compound fertilizer prepared in Examples 1-10 and Comparative Examples 1-2 was added to 100 g of soil and mixed well, placed in a 200 ml conical flask, and moistened with water. The mixture was cultured at 37°C for 72 h, and the soil urease activity was measured. The soil physical and chemical properties were alkaline nitrogen content of 20.4 mg / kg, available phosphorus content of 18.14 mg / kg, pH of 7.34, available potassium content of 192 mg / kg, and organic matter content of 15.4 g / kg.

[0039] Nitrate nitrogen content: 5g of the compound fertilizer prepared in Examples 1-10 and Comparative Examples 1-2 was added to 100g of soil and mixed, placed in a 200ml conical flask, and moistened with water. The mixture was cultured at 37°C for 72h, and the nitrate nitrogen content in the soil was determined according to GB / T 3597-2002 "Determination of Nitrate Nitrogen Content in Fertilizers - Nitrogen Reagent Gravimetric Method". The soil physical and chemical properties were alkaline nitrogen content of 20.4mg / kg, available phosphorus content of 18.14mg / kg, pH of 7.34, available potassium content of 192mg / kg, and organic matter content of 15.4g / kg.

[0040] Biuret content: The biuret content in the compound fertilizers prepared in Examples 1-10 and Comparative Example 1 was detected by high performance liquid chromatography according to GB / T 22924-2024.

[0041] Table 1 Combining Example 1 and Comparative Example 1 with Table 1, it can be seen that the anti-caking agent added in the present application can significantly reduce the caking rate of the compound fertilizer; Combining Examples 3 to 4 and Table 1, it can be seen that the anti-caking agent in Example 4 using stearate significantly improves the crushing resistance of the compound fertilizer. The reason is that the stearate can enter the gaps between the fertilizer particles, thereby improving the crushing resistance of the compound fertilizer. Combining Examples 4 to 5 and Table 1, it can be seen that compared with Example 4, Example 5 uses zinc stearate as the stearate in Example 5, which significantly reduces the content of nitrate nitrogen. The reason is that the zinc ion in zinc stearate acts as a bridge when dicyandiamide combines with the ammonia monooxygenase of nitrifying bacteria, and forms a coordination bond with a specific amino acid residue of the ammonia monooxygenase, thereby promoting the combination of dicyandiamide and ammonia monooxygenase, thereby improving the nitrification inhibitory effect of the nitrification inhibitor; Combining Examples 5 to 6 and Table 1, it can be seen that the use of dicyandiamide and trichloromethylpyridine in Example 6 significantly reduces the content of nitrate nitrogen; It can be seen from Examples 9 to 10 and Table 1 that the premixing of humic acid and yucca extract in Example 10 allows the humic acid to form a protective film on the surface of the yucca extract, reducing the contact between ultraviolet rays and the yucca extract, so that the ultraviolet rays are not easy to decompose the yucca extract, thereby improving the overall stability of the fertilizer and further reducing the urease activity.

[0042] Combining 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 allows the vermiculite powder to adsorb the yucca extract, so that after the vermiculite powder and yucca extract enter the soil as fertilizer, the vermiculite powder can absorb heat during the day and release heat at night to reduce the temperature change of the soil, thereby reducing the effect of soil temperature change on the activity of the yucca extract; in addition, the premixing of humic acid with vermiculite powder and yucca extract in Example 11 allows the viscous humic acid to bind the vermiculite powder and yucca extract entering the soil more tightly, so as to further reduce the effect of soil temperature change on the activity of the yucca extract.

[0043] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preparing a highly active urea-based compound fertilizer, characterized in that: The steps include: S1, melting urea, and then mixing it evenly with other components to obtain a mixed slurry; S2, granulating the mixed slurry and cooling it to obtain fertilizer; S3. Spraying the fertilizer with an anti-caking agent to obtain a product; the high-activity urea-based compound fertilizer comprises 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.

2. The method for preparing a highly active urea-based compound fertilizer according to claim 1, wherein: The mass parts of the components 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.

3. The method for preparing a highly active urea-based compound fertilizer according to claim 2, wherein: The anti-caking agent is stearate.

4. The method for preparing a highly active urea-based compound fertilizer according to claim 3, characterized in that: The stearate is zinc stearate.

5. The method for preparing a highly active urea-based compound fertilizer according to claim 2, wherein: The nitrification inhibitor comprises dicyandiamide and trichloromethyl pyridine, and the mass ratio of the dicyandiamide to trichloromethyl pyridine is 1:(1-1.5).

6. The method for preparing a highly active urea-based compound fertilizer according to claim 2, characterized in that: The urease inhibitor is yucca extract.

7. A method for preparing a highly active urea-based compound fertilizer according to claim 6, characterized in that: The S1, dissolving humic acid in water to obtain a mixture, then mixing the urease inhibitor with the mixture and drying to obtain a preform; melting urea, then sequentially adding vermiculite powder, monoammonium phosphate, potassium sulfate, the preform, a phosphorus activator, agricultural selenium fertilizer, zinc sulfate, borax, and a nitrification inhibitor and mixing evenly to obtain a mixed slurry.

8. A method for preparing a highly active urea-based compound fertilizer according to claim 2, characterized in that: In the step S1, a portion of the vermiculite powder and the urease inhibitor are mixed to obtain a first mixture, and humic acid is dissolved in water to obtain a second mixture, and then the first mixture and the second mixture are mixed and dried to obtain a preform; urea is melted, and then the remaining vermiculite powder, monoammonium phosphate, potassium sulfate, the preform, a phosphorus activator, an agricultural selenium fertilizer, zinc sulfate, borax, and a nitrification inhibitor are added in sequence and mixed evenly to obtain a mixed slurry.

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