Slow-release fertilizer and preparation method thereof

Abstract

The invention relates to a slow-release fertilizer and a preparation method thereof, and belongs to the technical field of slow-release fertilizers. The preparation method of the slow-release fertilizer comprises the following steps: treating zeolite, a phosphorus-containing substance, organic acid salt and water to obtain pretreated zeolite; roasting the pretreated zeolite for 1-5 hours to obtain chambering zeolite; treating the pore-expanded zeolite with ammonium salt, molybdate, potassium sulfate, phosphate and water for 1.5-3.0 hours, and washing to obtain modified zeolite; uniformly mixing the modified zeolite with lignocellulose, a compound fertilizer, sodium alginate and silica gel to obtain a mixed material; and granulating the mixed material to obtain the slow-release fertilizer with the particle size of 3.0-5.0 mm. The slow-release fertilizer disclosed by the invention not only has an excellent slow-release effect, but also can improve and maintain the soil fertility, is beneficial to improving the porosity, porosity and air permeability of soil, is beneficial to ensuring the nutrition of crops in the whole growth cycle, and increases the crop yield.

Description

Technical Field

[0001] The present invention relates to the technical field of slow-release fertilizers, and more particularly to a slow-release fertilizer and a preparation method thereof.

[0002] Fertilizer plays a very important role in increasing crop yields. According to surveys and statistics, about 70% of the nutrients needed for plant growth come from fertilizers. The application of fertilizers can significantly increase crop yields and total output; fertilizer input accounts for about half of the total agricultural production input. Ordinary fertilizers have serious nutrient losses and low fertilizer utilization rates, and may also cause soil compaction, environmental pollution and other problems. Slow-release fertilizers can effectively control the release of fertilizer nutrients, reduce nutrient loss, improve fertilizer utilization efficiency, and improve the soil environment. While achieving growth, it is also conducive to reducing cost inputs and saving labor, and has received widespread attention from government departments, research departments, and fertilizer production companies.

[0003] Common slow-release fertilizers in the prior art include: coated fertilizers, chemically synthesized slow-release fertilizers, and porous material-based slow-release fertilizers. Coated fertilizers are prepared by coating the surface of ordinary fertilizers with organic or inorganic hydrophobic materials, and the nutrients are released after the film layer breaks. Chemically synthesized slow-release fertilizers mainly refer to a type of fertilizer that bonds chemical components to high molecular polymers through covalent bonds or ionic bonds, and requires the hydrolysis of microorganisms or enzymes in the soil to break the chemical bonds and slowly release nutrients. Porous material-based slow-release fertilizers use porous materials as carriers and utilize the good absorption and ion exchange properties of porous materials to achieve different degrees of slow-release effects on nitrogen fertilizers, phosphate fertilizers, and potash fertilizers. However, the coatings and synthetic chemical components in the coated fertilizers and chemically synthesized slow-release fertilizers in the prior art may remain in the soil after the fertilizer nutrients are released, which poses a risk of environmental pollution and is not conducive to the sustainable development of agriculture. There are relatively few studies on existing porous material-based slow-release fertilizers. The types of porous materials include diatomaceous earth, bentonite, and zeolite, and they are mainly based on the slow-release of nitrogen fertilizers such as urea, and the slow-release effect is not ideal. Summary of the invention

[0004] In order to solve the existing porous material base, the purpose of the present invention is to provide a slow-release fertilizer and a preparation method thereof.

[0005] The method for preparing the slow-release fertilizer of the present invention comprises the following steps:

[0006] (1) mixing zeolite with a phosphorus-containing substance, an organic acid salt, and water in a mass ratio of 1:0.01-0.10:0.10-0.50:5-10, adjusting the pH to 1.5-2.0, treating at a temperature of 60° C. to 95° C. for 6.0 to 10.0 hours, filtering, and washing to obtain a pretreated zeolite;

[0007] (2) calcining the pretreated zeolite at 180-300° C. and 50-100% steam atmosphere for 1-5 hours to obtain pore-enlarged zeolite;

[0008] (3) mixing the expanded zeolite with ammonium salt, molybdate, potassium sulfate, phosphate and water in a mass ratio of 1:0.5-1.0:0-0.03:0.1-0.5:0.05-0.15:5-10, adjusting the pH to 3.0-4.5, treating at a temperature of 75° C. to 90° C. for 1.5-3.0 hours, and then washing to obtain a modified zeolite;

[0009] (4) uniformly mixing the modified zeolite with lignocellulose, compound fertilizer, sodium diatomite and silica gel to obtain a mixed material;

[0010] (5) The mixed material is granulated by a disc granulator to obtain a slow-release fertilizer with a particle size of 3.0 to 5.0 mm.

[0011] The zeolite is natural zeolite, artificial zeolite or recycled zeolite. The zeolite may be, for example, analcime, clinocite, chabazite, faujasite, phillipsite, mordenite or natrolite.

[0012] Wherein, the phosphorus-containing substance is selected from at least one of phosphoric acid, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, phosphorous acid, and pyrophosphoric acid.

[0013] Wherein, the organic acid salt is selected from at least one of ammonium oxalate, ammonium citrate, ammonium tartrate or ammonium propionate.

[0014] Wherein, the ammonium salt is selected from one of ammonium chloride, ammonium sulfate, ammonium phosphate, diammonium hydrogen phosphate or diammonium dihydrogen phosphate.

[0015] Wherein, the molybdate is selected from at least one of potassium molybdate, sodium molybdate or ammonium molybdate.

[0016] Wherein, in step (3), the mass ratio of the pore-expanded zeolite to ammonium salt, molybdate, potassium sulfate, phosphate and water is preferably 1:0.5-1.0:0.01-0.03:0.15-0.5:0.05-0.10:5-10.

[0017] Wherein, the mass ratio of the modified zeolite to lignocellulose, compound fertilizer, sodium diatomite and silica gel is 1:1:0-1:0.02-0.10:0.01-0.10; more preferably, 1:1:0.1-0.5:0.03-0.08:0.01-0.10.

[0018] The second aspect of the present invention also relates to a slow-release fertilizer prepared by the above method.

[0019] The third aspect of the present invention is the use of the above slow-release fertilizer, which is used for the production of Solanaceae vegetables, such as peppers.

[0020] Compared with the prior art, the slow-release fertilizer and the preparation method thereof of the present invention have the following beneficial effects:

[0021] The slow-release fertilizer of the present invention is loaded with macro and micro nutrients necessary for crop growth by performing specific modification treatment on zeolite, and is prepared into a composite granular fertilizer by combining lignocellulose, compound fertilizer and sodium diatomite. The composite granular fertilizer not only has excellent slow-release effect and improves the utilization rate of fertilizer, but also can improve and maintain soil fertility and become a storage place for water and fertilizer; it is beneficial to improve the looseness, porosity and air permeability of the soil, and is beneficial to ensure the nutrition of crops throughout the growth cycle and increase crop yield. DETAILED DESCRIPTION

[0022] The slow-release fertilizer and the preparation method thereof of the present invention will be further described below in conjunction with specific embodiments to help those skilled in the art to have a more complete, accurate and in-depth understanding of the technical solution of the present invention.

[0023] The invention provides a method for preparing a slow-release fertilizer containing three nutrients, namely nitrogen, phosphorus and potassium, which are necessary for crop growth. The method comprises the following steps: first, mixing a phosphorus-containing substance, an organic acid salt, water and a zeolite according to a mass ratio of 0.01-0.10:0.10-0.50:5-10:1, and adjusting the pH to 1.5-2.0; treating the mixture at a temperature of 60-95°C for 6.0-10.0 hours, filtering and washing the mixture to obtain a pretreated zeolite; calcining the pretreated zeolite at 180-300°C and a 50-100% water vapor atmosphere for 1-5 hours to obtain a pore-enlarged zeolite; through the ion exchange and calcination treatment, not only part of the aluminum in the zeolite skeleton structure is removed, but also the phosphorus-containing nutrients are exchanged into the zeolite structure, and under low pH conditions, it is more conducive to the subsequent loading and adsorption of nutrients. After the pore expansion treatment, the pore-expanded zeolite is mixed with ammonium salt, molybdate, potassium sulfate, phosphate and water in a mass ratio of 1:0.5-1.0:0-0.03:0.1-0.5:0.05-0.15:5-10, the pH is adjusted to 3.0-4.5, and the mixture is treated at a temperature of 75°C to 90°C for 1.5-3.0 hours and then washed to obtain a modified zeolite. The mass ratio of the pore-expanded zeolite to the ammonium salt, molybdate, potassium sulfate, phosphate and water is preferably 1:0.5-1.0:0.01-0.03:0.15-0.5:0.05-0.10:5-10; the modified zeolite does not need to be calcined again, and in fact, if it is calcined, its sustained release effect will be deteriorated. Subsequently, the modified zeolite is further mixed with lignocellulose, compound fertilizer, sodium diatomite and silica gel to obtain a mixed material; the mixed material is granulated by a disc granulator to obtain a slow-release fertilizer with a particle size of 3.0 to 5.0 mm. The mass ratio of the modified zeolite to lignocellulose, compound fertilizer, sodium diatomite and silica gel is 1:1:0 to 1:0.02 to 0.10:0.01 to 0.10; more preferably, 1:1:0.1 to 0.5:0.03 to 0.08:0.01 to 0.10. In the present invention, silica gel is used as a binder, which is more conducive to maintaining the slow-release effect of the slow-release fertilizer in the early stage of application with sodium diatomite and lignocellulose, ensuring that the nutrients are effectively absorbed and utilized by crops. In the present invention, the zeolite is a natural zeolite, an artificial zeolite or a recycled zeolite. As an example, the zeolite can be selected from analcime, clinocite, chabazite, faujasite, cross zeolite, mordenite or sodium zeolite. The phosphorus-containing substance is selected from at least one of phosphoric acid, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, phosphorous acid, and pyrophosphoric acid. The organic acid salt is selected from at least one of ammonium oxalate, ammonium citrate, ammonium tartrate, or ammonium propionate. The ammonium salt is selected from one of ammonium chloride, ammonium sulfate, ammonium phosphate, diammonium hydrogen phosphate, or ammonium dihydrogen phosphate. The molybdate is selected from at least one of potassium molybdate, sodium molybdate, or ammonium molybdate.In the present invention, molybdate enters the zeolite structure through ion exchange, and enters the soil with the help of the porous structure of the zeolite, which can effectively improve the utilization efficiency of trace fertilizers and has a significant effect on the growth and income increase of some crops, such as Solanaceae vegetables. The slow-release fertilizer of the present invention makes full use of the ion exchange and adsorption properties of the zeolite material, realizes the controllable slow release of the composite nutrients of crops, and effectively improves the utilization efficiency of the composite nutrients. The compound fertilizer described in the present invention is a compound fertilizer containing N, P, and K, for example, a compound fertilizer converted into effective ingredients of 15% N, 15% P2O5 and 15% K2O.

[0024] Example 1

[0025] First, 5g of ammonium phosphate and 30g of ammonium oxalate were added to 1000g of water and mixed evenly, and the pH was adjusted to 2.0 with sulfuric acid to obtain a treatment solution; 100g of NaY zeolite was prepared and crushed to 60 mesh, and then added to the above treatment solution, treated at 90°C for 10.0 hours, filtered and washed to obtain a pretreated zeolite; the pretreated zeolite was calcined at 280°C and 100% water vapor atmosphere for 5 hours to obtain a pore-enlarged zeolite. Then, the pore-enlarged zeolite was mixed with ammonium sulfate, ammonium molybdate, potassium sulfate, ammonium phosphate and water in a mass ratio of 1:0.5:0.01:0.2:0.10:10, and the pH was adjusted to 3.2 with sulfuric acid, treated at 80°C for 2.0 hours, and washed to obtain a modified zeolite. Subsequently, the modified zeolite is uniformly mixed with wood cellulose, compound fertilizer (effective ingredients 15% N, 15% P2O5 and 15% K2O), sodium diatomate and silica gel in a mass ratio of 1:1:0.5:0.06:0.05 to obtain a mixed material; finally, the mixed material is granulated by a disc granulator to obtain a slow-release fertilizer (water content 10.5%) with a particle size of 3.0 to 5.0 mm.

[0026] Example 2

[0027] First, 10g of phosphoric acid and 50g of ammonium citrate were added to 1000g of water and mixed evenly, and the pH was adjusted to 1.5 with sulfuric acid to obtain a treatment solution; 100g of NaY zeolite was prepared and crushed to 60 mesh, and then added to the above treatment solution, treated at 90°C for 6.0 hours, filtered and washed to obtain a pretreated zeolite; the pretreated zeolite was roasted at 280°C and 100% water vapor atmosphere for 3 hours to obtain a pore-enlarged zeolite. Then, the pore-enlarged zeolite was mixed with ammonium sulfate, sodium molybdate, potassium sulfate, ammonium phosphate and water in a mass ratio of 1:0.5:0.02:0.5:0.10:10, and the pH was adjusted to 3.0 with sulfuric acid, treated at 80°C for 2.0 hours, and washed to obtain a modified zeolite. Subsequently, the modified zeolite is uniformly mixed with lignocellulose, compound fertilizer (active ingredients 15% N, 15% P2O5 and 15% K2O), sodium diatomate and silica gel in a mass ratio of 1:1:0.1:0.08:0.10 to obtain a mixed material; finally, the mixed material is granulated by a disc granulator to obtain a slow-release fertilizer with a particle size of 3.0 to 5.0 mm (water content of 10.2%).

[0028] Example 3

[0029] First, 5g of ammonium phosphate and 30g of ammonium oxalate were added to 1000g of water and mixed evenly, and the pH was adjusted to 2.0 with sulfuric acid to obtain a treatment solution; 100g of NaY zeolite was prepared and crushed to 60 mesh, and then added to the above treatment solution, treated at 90°C for 10.0 hours, filtered and washed to obtain a pretreated zeolite; the pretreated zeolite was roasted at 280°C and 100% water vapor atmosphere for 5 hours to obtain an expanded zeolite. Then, the expanded zeolite was mixed with ammonium sulfate, potassium sulfate, ammonium phosphate and water in a mass ratio of 1:0.5:0.2:0.10:10, and the pH was adjusted to 3.2 with sulfuric acid, treated at 80°C for 2.0 hours, and washed to obtain a modified zeolite. Subsequently, the modified zeolite is uniformly mixed with lignocellulose, compound fertilizer (active ingredients 15% N, 15% P2O5 and 15% K2O), sodium diatomate and silica gel in a mass ratio of 1:1:0.5:0.06:0.05 to obtain a mixed material; finally, the mixed material is granulated by a disc granulator to obtain a slow-release fertilizer (water content 10.5%) with a particle size of 3.0 to 5.0 mm.

[0030] Comparative Example 1

[0031] First, 5g of ammonium phosphate and 30g of ammonium oxalate were added to 1000g of water and mixed evenly, and the pH was adjusted to 2.0 with sulfuric acid to obtain a treatment solution; 100g of NaY zeolite was prepared and crushed to 60 mesh, and then added to the above treatment solution, treated at 90°C for 3.0 hours, filtered and washed to obtain a pretreated zeolite; the pretreated zeolite was roasted at 280°C and 100% water vapor atmosphere for 5 hours to obtain a pore-enlarged zeolite. Then, the pore-enlarged zeolite was mixed with ammonium sulfate, ammonium molybdate, potassium sulfate, ammonium phosphate and water in a mass ratio of 1:0.5:0.01:0.2:0.10:10, and the pH was adjusted to 3.2 with sulfuric acid, treated at 80°C for 2.0 hours, and washed to obtain a modified zeolite. Subsequently, the modified zeolite is uniformly mixed with wood cellulose, compound fertilizer (effective ingredients 15% N, 15% P2O5 and 15% K2O), sodium diatomate and silica gel in a mass ratio of 1:1:0.5:0.06:0.05 to obtain a mixed material; finally, the mixed material is granulated by a disc granulator to obtain a slow-release fertilizer (water content 10.5%) with a particle size of 3.0 to 5.0 mm.

[0032] Comparative Example 2

[0033] First, 5g of ammonium phosphate and 30g of ammonium oxalate were added to 1000g of water and mixed evenly, and the pH was adjusted to 2.0 with sulfuric acid to obtain a treatment solution; 100g of NaY zeolite was prepared and crushed to 60 mesh, and then added to the above treatment solution, treated at 90°C for 10.0 hours, filtered and washed to obtain a pretreated zeolite; the pretreated zeolite was roasted at 280°C and 100% water vapor atmosphere for 5 hours to obtain a pore-enlarged zeolite. Then, the pore-enlarged zeolite was mixed with ammonium sulfate, ammonium molybdate, potassium sulfate, ammonium phosphate and water in a mass ratio of 1:0.5:0.01:0.2:0.10:10, and the pH was adjusted to 3.2 with sulfuric acid, treated at 80°C for 2.0 hours, and washed; then roasted at 350°C and 100% water vapor atmosphere for 5 hours to obtain a modified zeolite. Subsequently, the modified zeolite is uniformly mixed with wood cellulose, compound fertilizer (effective ingredients 15% N, 15% P2O5 and 15% K2O), sodium diatomate and silica gel in a mass ratio of 1:1:0.5:0.06:0.05 to obtain a mixed material; finally, the mixed material is granulated by a disc granulator to obtain a slow-release fertilizer (water content 10.5%) with a particle size of 3.0 to 5.0 mm.

[0034] Comparative Example 3

[0035] First, 5g of ammonium phosphate and 30g of ammonium oxalate were added to 1000g of water and mixed evenly, and the pH was adjusted to 2.0 with sulfuric acid to obtain a treatment solution; 100g of NaY zeolite was prepared and crushed to 60 mesh, and then added to the above treatment solution, treated at 90°C for 10.0 hours, filtered and washed to obtain a pretreated zeolite; the pretreated zeolite was calcined at 280°C and 100% water vapor atmosphere for 5 hours to obtain a pore-enlarged zeolite. Then, the pore-enlarged zeolite was mixed with ammonium sulfate, ammonium molybdate, potassium sulfate, ammonium phosphate and water in a mass ratio of 1:0.5:0.01:0.2:0.10:10, and the pH was adjusted to 3.2 with sulfuric acid, treated at 80°C for 2.0 hours, and washed to obtain a modified zeolite. Subsequently, the modified zeolite is uniformly mixed with biochar, compound fertilizer (active ingredients 15% N, 15% P2O5 and 15% K2O), sodium diatomate and gelatin in a mass ratio of 1:1:0.5:0.06:0.05 to obtain a mixed material; finally, the mixed material is granulated using a disc granulator to obtain a slow-release fertilizer (water content 10.5%) with a particle size of 3.0 to 5.0 mm.

[0036] Comparative Example 4

[0037] First, 5g of ammonium phosphate and 30g of ammonium oxalate were added to 1000g of water and mixed evenly, and the pH was adjusted to 2.0 with sulfuric acid to obtain a treatment solution; 100g of NaY zeolite was prepared and crushed to 60 mesh, and then added to the above treatment solution, treated at 90°C for 10.0 hours, filtered and washed to obtain a pretreated zeolite; the pretreated zeolite was calcined at 280°C and 100% water vapor atmosphere for 5 hours to obtain a pore-enlarged zeolite. Then, the pore-enlarged zeolite was mixed with ammonium sulfate, ammonium molybdate, potassium sulfate, ammonium phosphate and water in a mass ratio of 1:0.5:0.01:0.2:0.10:10, and the pH was adjusted to 3.2 with sulfuric acid, treated at 80°C for 2.0 hours, and washed to obtain a modified zeolite. Subsequently, the modified zeolite is uniformly mixed with wood cellulose, compound fertilizer (effective ingredients 15% N, 15% P2O5 and 15% K2O) and silica gel in a mass ratio of 1:1:0.5:0.05 to obtain a mixed material; finally, the mixed material is granulated by a disc granulator to obtain a slow-release fertilizer (water content 10.5%) with a particle size of 3.0 to 5.0 mm.

[0038] Comparative Example 5

[0039] First, 5g of ammonium phosphate and 30g of ammonium oxalate were added to 1000g of water and mixed evenly, and the pH was adjusted to 2.0 with sulfuric acid to obtain a treatment solution; 100g of NaY zeolite was prepared and crushed to 60 mesh, and then added to the above treatment solution, treated at 90°C for 3.0 hours, filtered and washed to obtain a pretreated zeolite; the pretreated zeolite was calcined at 280°C and 100% water vapor atmosphere for 5 hours to obtain a pore-enlarged zeolite. Then, the pore-enlarged zeolite was mixed with ammonium sulfate, potassium sulfate, ammonium phosphate and water in a mass ratio of 1:0.5:0.2:0.10:10, and the pH was adjusted to 3.2 with sulfuric acid, treated at 80°C for 2.0 hours, and washed to obtain a modified zeolite. Subsequently, the modified zeolite is uniformly mixed with wood cellulose, compound fertilizer (effective ingredients 15% N, 15% P2O5 and 15% K2O), ammonium molybdate, sodium diatomate and silica gel in a mass ratio of 1:1:0.5:0.02:0.06:0.05 to obtain a mixed material; finally, the mixed material is granulated by a disc granulator to obtain a slow-release fertilizer with a particle size of 3.0 to 5.0 mm (water content of 10.5%).

[0040] Comparative Example 6

[0041] First, 5g of ammonium phosphate was added to 1000g of water and mixed evenly, and the pH was adjusted to 2.0 with sulfuric acid to obtain a treatment solution; 100g of NaY zeolite was prepared and crushed to 60 mesh, and then added to the above treatment solution, treated at 90°C for 10.0 hours, filtered and washed to obtain a pretreated zeolite; the pretreated zeolite was roasted at 280°C and 100% water vapor atmosphere for 5 hours to obtain a pore-enlarged zeolite. Then, the pore-enlarged zeolite was mixed with ammonium sulfate, ammonium molybdate, potassium sulfate, ammonium phosphate and water in a mass ratio of 1:0.5:0.01:0.2:0.10:10, and the pH was adjusted to 3.2 with sulfuric acid, treated at 80°C for 2.0 hours, and washed to obtain a modified zeolite. Subsequently, the modified zeolite is uniformly mixed with lignocellulose, compound fertilizer (active ingredients 15% N, 15% P2O5 and 15% K2O), sodium diatomate and silica gel in a mass ratio of 1:1:0.5:0.06:0.05 to obtain a mixed material; finally, the mixed material is granulated by a disc granulator to obtain a slow-release fertilizer (water content 10.5%) with a particle size of 3.0 to 5.0 mm.

[0042] Performance Testing

[0043] The nutrient extract was prepared by the static water extraction method specified in HG / T4215-2011. The contents of nitrogen, phosphorus and potassium were determined by Kjeldahl nitrogen determination, molybdenum antimony anti-spectrophotometry and flame photometry respectively. The time required for the dissolved nutrients to reach 80% of the total mass of the nutrients was the nutrient release period.

[0044] 10g of slow-release fertilizer prepared in Examples 1 to 3 and Comparative Examples 1 to 6 were respectively placed in nylon mesh bags, and after sealing, the nylon mesh bags were placed in a plastic bottle with 200mL of distilled water, and sealed and placed in a 15°C biochemical constant temperature incubator. The sampling time was 1d, 7d, 28d, and 60d, and the nutrient dissolution rate reached 80%, which was considered to be completely released. When sampling, all the samples were poured into a glass bottle for testing, and then distilled water was added again, sealed, and continued to be placed in a 15°C biochemical constant temperature incubator.

[0045] Table 1 shows the nutrient release rates and nutrient release periods of the slow-release fertilizers of various embodiments and comparative examples at 1 day, 7 days, 28 days, and 60 days.

[0046] Table 1

[0047]

[0048] Planting test

[0049] In a certain place in Henan Province, 1200 chili pepper seedlings were transplanted per mu of land, and the slow-release fertilizer granules of Examples 1 to 3 and Comparative Examples 1 to 6 were applied at a dosage of 5 kg / mu, and the slow-release fertilizer granules were applied at a distance of about 8 to 10 cm from the chili pepper seedlings. Under conventional field management, the entire growth cycle from seedling to harvest was about 120 days, and the chili pepper yield was statistically shown in Table 2.

[0050] Table 2

[0051]

[0052] For ordinary technicians in this field, the specific embodiments are only illustrative descriptions of the present invention. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solutions of the present invention, or the dog speed and technical solutions of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A method for preparing a slow-release fertilizer, characterized in that The following steps are involved: (1) mixing zeolite with a phosphorus-containing substance, an organic acid salt, and water in a mass ratio of 1:0.01-0.10:0.10-0.50:5-10, adjusting the pH to 1.5-2.0, treating at a temperature of 60° C. to 95° C. for 6.0 to 10.0 hours, filtering, and washing to obtain a pretreated zeolite; (2) calcining the pretreated zeolite at 180-300° C. and 50-100% steam atmosphere for 1-5 hours to obtain pore-enlarged zeolite; (3) The expanded zeolite is mixed with ammonium salt, molybdate, potassium sulfate, phosphate and water in a ratio of 1:0.5 to 1.0:0 to 0.03: Mixing the mixture in a mass ratio of 0.1-0.5:0.05-0.15:5-10, adjusting the pH to 3.0-4.5, treating the mixture at a temperature of 75° C. to 90° C. for 1.5-3.0 hours, and then washing the mixture to obtain a modified zeolite; (4) uniformly mixing the modified zeolite with lignocellulose, compound fertilizer, sodium diatomite and silica gel to obtain a mixed material; (5) The mixed material is granulated by a disc granulator to obtain a slow-release fertilizer with a particle size of 3.0 to 5.0 mm.

2. The method for preparing a slow-release fertilizer according to claim 1, characterized in that: The zeolite is natural zeolite, artificial zeolite or recycled zeolite.

3. The method for preparing the slow-release fertilizer according to claim 1, characterized in that: The phosphorus-containing substance is selected from at least one of phosphoric acid, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, phosphorous acid, and pyrophosphoric acid.

4. The method for preparing the slow-release fertilizer according to claim 1, characterized in that: The organic acid salt is selected from at least one of ammonium oxalate, ammonium citrate, ammonium tartrate or ammonium propionate.

5. The method for preparing the slow-release fertilizer according to claim 1, characterized in that: The ammonium salt is selected from one of ammonium chloride, ammonium sulfate, ammonium phosphate, diammonium hydrogen phosphate or diammonium dihydrogen phosphate.

6. The method for preparing the slow-release fertilizer according to claim 1, characterized in that: The molybdate is selected from at least one of potassium molybdate, sodium molybdate or ammonium molybdate.

7. The method for preparing a slow-release fertilizer according to claim 1, characterized in that: In step (3), the mass ratio of the pore-expanded zeolite to ammonium salt, molybdate, potassium sulfate, phosphate and water is 1:0.5-1.0:0.01-0.03:0.15-0.5:0.05-0.10:5-10.

8. The method for preparing a slow-release fertilizer according to claim 1, characterized in that: The mass ratio of the modified zeolite to the wood cellulose, the compound fertilizer, the sodium diatomite and the silica gel is 1:1:0-1:0.02-0.10:0.01-0.

10.

9. A slow-release fertilizer, characterized in that: The method is prepared according to any one of claims 1 to 8.

10. The use of the slow-release fertilizer according to claim 9, characterized in that: The fertilizer is used for Solanaceae vegetables.

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