Special soil-improving disease-resistant type coated controlled-release fertilizer for wheat and preparation method thereof

Abstract

The invention relates to a special soil-improving disease-resistant coated controlled-release fertilizer for wheat and a preparation method thereof. The preparation method comprises the following steps: step 1, preparing a fertilizer particle core; step 2, preparing modified starch inner coating liquid; step 3, forming an inner coating film; and step 4, forming the biochar outer coating film. According to the special soil-improving disease-resistant coated controlled-release fertilizer for wheat, provided by the invention, fertilizer particles are of a multi-layer structure. The inner-layer coating is modified starch and is prepared by cross-linking a seaweed extract and starch, so that the resistance of wheat to a bad environment can be improved; the outer coating is modified biochar, so that the release rate of nutrients can be reduced, and the physicochemical properties and microenvironment of the soil can be improved.

Description

Technical Field

[0001] The invention relates to the field of fertilizers, and in particular to a special coated controlled-release fertilizer for soil-improving disease-resistant wheat and a preparation method thereof. Background Art

[0002] Wheat is the third largest grain crop in my country. In recent years, frequent extreme climate and deteriorating soil quality have had a negative impact on wheat growth and development. Abiotic stresses such as drought and high temperature, and biotic stresses such as sheath blight and stripe rust have directly led to reduced wheat production.

[0003] Biochar is a solid substance formed by high-temperature pyrolysis or carbonization of biological residues such as plant residues and agricultural waste. It has a large specific surface area and pore volume. It can not only improve soil texture and maintain soil moisture, but also has good water and fertilizer retention capabilities. Therefore, using biochar as a coating material can adsorb and store nutrients in fertilizers and slowly release them to plants, providing a continuous nutrient supply and reducing fertilizer waste. At the same time, biochar can improve soil structure, increase soil water and fertilizer retention capabilities, and promote plant growth.

[0004] Seaweed fertilizer is a new type of fertilizer made from seaweed as raw material or compounded with bulk fertilizers. Seaweed contains not only organic physiologically active substances such as seaweed polysaccharides, plant hormones, and betaine, but also inorganic mineral elements such as calcium, magnesium, zinc, and iron. Therefore, using seaweed fertilizer in agricultural production can improve crop resistance and increase crop yields. Currently, seaweed fertilizers on the market are mainly divided into seaweed compound fertilizers and seaweed liquid fertilizers. If they are directly applied to the soil, the nutrients are released quickly and are difficult to be efficiently and directly absorbed and utilized by plants. Summary of the invention

[0005] In view of the problems existing in the prior art, the object of the present invention is to provide a special coated controlled-release fertilizer for soil-improving disease-resistant wheat and a preparation method thereof.

[0006] The purpose of the present invention is achieved by the following technical solutions:

[0007] In a first aspect, the present invention discloses a method for preparing a soil-improving disease-resistant wheat coated controlled-release fertilizer, comprising the following steps:

[0008] Step 1, preparing the fertilizer granule core:

[0009] Weigh nitrogen fertilizer, phosphate fertilizer and potash fertilizer, mix them in deionized water, add gum arabic, stir thoroughly until uniform, granulate in a disc granulator, sieve, and obtain fertilizer granule cores;

[0010] Step 2, preparing modified starch inner coating solution:

[0011] The amino starch is added to deionized water for gelatinization, and then the carboxymethylated seaweed extract is added. Under the action of a catalyst, the temperature is raised to 80-100°C, and the mixture is stirred for 2-4 hours. After the reaction is completed, ammonia water is added dropwise until the pH of the reaction solution is neutral, and the mixture is cooled to room temperature to obtain a modified starch inner coating solution.

[0012] Step 3, forming the inner envelope:

[0013] The modified starch coating liquid is sprayed on the surface of the fertilizer particle core, and the modified starch coating fertilizer is obtained by disk granulation;

[0014] Step 4, forming the biochar outer film:

[0015] The biochar, attapulgite, sodium carboxymethyl cellulose and vegetable oil are uniformly mixed, sprayed on the surface of modified starch coated fertilizer, and dried by blast heating to obtain a soil-modified disease-resistant wheat coated controlled-release fertilizer.

[0016] Preferably, in step 1, the nitrogen fertilizer is one or more of urea, ammonium nitrate, and calcium ammonium nitrate; the phosphate fertilizer is one or more of monoammonium phosphate or diammonium phosphate; and the potash fertilizer is one or more of potassium chloride or potassium sulfate.

[0017] Preferably, in step 1, the mass ratio of nitrogen fertilizer, phosphorus fertilizer and potash fertilizer is 170-190:200-220:50-70.

[0018] Preferably, in step 1, the particle size of the fertilizer particle core is 20-30 mesh.

[0019] Preferably, in step 2, the method for preparing aminated starch comprises:

[0020] Weigh corn starch and dimethyl sulfoxide, mix them, heat them to 80-90°C, stir them thoroughly until a uniform mixed solution is formed, then drop the aminosilane coupling agent solution, keep the mixture warm and stir for 1-2 hours after the dropwise addition, then cool it to room temperature, discharge it into anhydrous ethanol, centrifuge, wash and dry it to obtain amino starch.

[0021] Preferably, during the preparation of the amino starch, the purity of the corn starch is ≥98%, the water content is ≤14%, and the acidity is ≤1.8.

[0022] Preferably, during the preparation of the amino starch, the mass ratio of corn starch, dimethyl sulfoxide and aminosilane coupling agent solution is 1:60-80:20-40.

[0023] Preferably, in the preparation process of the amino starch, the aminosilane coupling agent solution is obtained by mixing KH-550 and deionized water in a mass ratio of 1:8-12.

[0024] Preferably, in step 2, the method for preparing the carboxymethylated seaweed extract comprises:

[0025] S1. Wash, dry and crush the seaweed to obtain seaweed powder, add the seaweed powder into a sodium carbonate solution, stir at a temperature of 50-60° C. and a speed of 200-300 rpm for 6-8 hours, cool to room temperature, collect the supernatant by centrifugation, and vacuum dry to obtain a seaweed extract;

[0026] S2. Add the seaweed extract to the sodium hydroxide solution, stir well, then add chloroacetic acid solution, raise the temperature to 50-70°C, keep warm for 2-5 hours, then cool to room temperature, add glacial acetic acid until the pH of the reaction solution is neutral, collect the supernatant by centrifugation, and vacuum dry to obtain the carboxymethylated seaweed extract.

[0027] Preferably, in S1, the mass fraction of the sodium carbonate solution is 20%-30%, and the mass ratio of the seaweed powder to the sodium carbonate solution is 1:10-20.

[0028] Preferably, in S2, the mass fraction of the sodium hydroxide solution is 8%-16%, the mass fraction of the chloroacetic acid solution is 3%-8%, and the mass ratio of the seaweed extract, the chloroacetic acid solution and the sodium hydroxide solution is 1:2-4:10-20.

[0029] Preferably, in step 2, the gelatinization treatment conditions are: gelatinization temperature 60-70° C., gelatinization time 0.5-1 h.

[0030] Preferably, in step 2, the mass ratio of the amino starch, the carboxymethylated seaweed extract and the deionized water is 1:0.3-0.8:40-60.

[0031] Preferably, in step 2, the catalyst is p-toluenesulfonic acid, and the added amount is 2%-6% of the amino starch.

[0032] Preferably, in step 3, the spraying thickness of the modified starch inner coating liquid is 0.2-0.5 mm.

[0033] Preferably, in step 4, the mass ratio of biochar, attapulgite, sodium carboxymethyl cellulose and vegetable oil is 20-25:20-25:2-2.5:10-12.

[0034] Preferably, in step 4, the spraying thickness is 0.3-0.6 mm.

[0035] In a second aspect, the present invention discloses a coated controlled-release fertilizer specially used for soil-improving and disease-resistant wheat, which is prepared by the above-mentioned preparation method.

[0036] The beneficial effects of the present invention are:

[0037] 1. The soil-improving disease-resistant wheat coated controlled-release fertilizer provided by the present invention has a multi-layer structure. The inner coating is modified starch, which is prepared by cross-linking seaweed extract and starch, and can improve the resistance of wheat to adverse environments; the outer coating is modified biochar, which can not only reduce the release rate of nutrients, but also improve the physical and chemical properties and microenvironment of the soil.

[0038] 2. The coated controlled-release fertilizer for soil-improving and disease-resistant wheat provided by the present invention uses modified starch to reduce the release rate of seaweed active substances. The modified starch is prepared by cross-linking reaction between amino starch and carboxymethylated seaweed extract, which can enable wheat to acquire long-term ability to resist adverse environments.

[0039] 3. The modified starch-modified biochar double-layer coating structure used in the present invention is an environmentally friendly material and will not cause any impact on the environment after the internal nutrients are released. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is described below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to limit the scope of the present invention. The change or adjustment of the relative relationship thereof shall also be regarded as the scope of the present invention without substantially changing the technical content.

[0041] In order to better understand the above technical scheme, the exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0042] The present invention will be further described below in conjunction with the following examples.

[0043] Example 1

[0044] A method for preparing a soil-improving disease-resistant wheat coated controlled-release fertilizer comprises the following steps:

[0045] Step 1, preparing the fertilizer granule core:

[0046] Weigh urea, monoammonium phosphate and potassium chloride, mix them in deionized water, add gum arabic, the mass ratio of urea, monoammonium phosphate, potassium chloride, gum arabic and deionized water is 180:210:60:15:500, stir until uniform, granulate in a disc granulator, pass through a 30-mesh sieve, and obtain a fertilizer granule core;

[0047] Step 2, preparing modified starch inner coating solution:

[0048] S1. Preparation of amino starch:

[0049] Weigh corn starch (purity of corn starch ≥ 98%, water content ≤ 14%, acidity ≤ 1.8) and dimethyl sulfoxide, mix, heat to 85°C, stir thoroughly until a uniform mixed solution is formed, then drop aminosilane coupling agent solution (KH-550: deionized water mass ratio is 1:10), the mass ratio of corn starch, dimethyl sulfoxide and aminosilane coupling agent solution is 1:70:30, keep warm and stir for 1.5h after the dropwise addition, then cool to room temperature, discharge in anhydrous ethanol, centrifuge, wash and dry to obtain amino starch;

[0050] S2, washing, drying and crushing the seaweed to obtain seaweed powder, adding the seaweed powder to a 25% sodium carbonate solution by mass, the mass ratio of the seaweed powder to the sodium carbonate solution being 1:15, stirring at a temperature of 55° C. and a speed of 250 rpm for 7 h, cooling to room temperature, collecting the supernatant by centrifugation, and vacuum drying to obtain a seaweed extract;

[0051] S3, adding the seaweed extract to a sodium hydroxide solution with a mass fraction of 12%, stirring thoroughly, then dropping chloroacetic acid with a mass fraction of 5%, the mass ratio of the seaweed extract, the chloroacetic acid solution and the sodium hydroxide solution is 1:3:15, heating to 60°C, keeping warm for 3h, then cooling to room temperature, dropping glacial acetic acid until the pH of the reaction solution is neutral, centrifuging to collect the supernatant, and vacuum drying to obtain a carboxymethylated seaweed extract;

[0052] S4. Add the amino starch into deionized water for gelatinization treatment, the gelatinization temperature is 65°C, the gelatinization time is 0.5h, and then add the carboxymethylated seaweed extract, the mass ratio of the amino starch, the carboxymethylated seaweed extract and the deionized water is 1:0.5:50, under the action of the catalyst p-toluenesulfonic acid, the addition amount is 4% of the amino starch, the temperature is raised to 90°C, and the mixture is stirred for 3h. After the reaction is completed, ammonia water is added dropwise until the pH of the reaction solution is neutral, and the temperature is lowered to room temperature to obtain a modified starch inner coating liquid.

[0053] Step 3, forming the inner envelope:

[0054] The modified starch coating liquid is sprayed on the surface of the fertilizer particle core with a spraying thickness of 0.4 mm, and the modified starch coated fertilizer is obtained by disk granulation;

[0055] Step 4, forming the biochar outer film:

[0056] After the biochar, attapulgite, sodium carboxymethyl cellulose and vegetable oil are evenly mixed, the mass ratio of biochar, attapulgite, sodium carboxymethyl cellulose and vegetable oil is 22:21:2:11, and sprayed on the surface of modified starch coated fertilizer with a spraying thickness of 0.3-0.6mm. Under blast heating and drying, a special coated controlled-release fertilizer for soil-modified and disease-resistant wheat is obtained.

[0057] Example 2

[0058] A method for preparing a soil-improving disease-resistant wheat coated controlled-release fertilizer comprises the following steps:

[0059] Step 1, preparing the fertilizer granule core:

[0060] Weigh ammonium nitrate, diammonium phosphate and potassium sulfate, mix them in deionized water, add gum arabic, the mass ratio of ammonium nitrate, diammonium phosphate, potassium sulfate, gum arabic and deionized water is 170:200:50:10:500, stir until uniform, granulate in a disc granulator, pass through a 20-mesh sieve, and obtain a fertilizer granule core;

[0061] Step 2, preparing a modified starch inner coating solution, the same as in Example 1;

[0062] Step 3, forming the inner envelope:

[0063] The modified starch coating liquid is sprayed on the surface of the fertilizer particle core with a spraying thickness of 0.2 mm, and the modified starch coated fertilizer is obtained by disk granulation;

[0064] Step 4, forming the biochar outer film:

[0065] After the biochar, attapulgite, sodium carboxymethyl cellulose and vegetable oil are evenly mixed, the mass ratio of biochar, attapulgite, sodium carboxymethyl cellulose and vegetable oil is 20:20:2:10, and sprayed on the surface of the modified starch coated fertilizer with a spraying thickness of 0.3 mm. Under the condition of forced air heating and drying, a special coated controlled-release fertilizer for soil-modified and disease-resistant wheat is obtained.

[0066] Example 3

[0067] A method for preparing a soil-improving disease-resistant wheat coated controlled-release fertilizer comprises the following steps:

[0068] Step 1, preparing the fertilizer granule core:

[0069] Weigh calcium ammonium nitrate, monoammonium phosphate and potassium chloride, mix them in deionized water, add gum arabic, the mass ratio of calcium ammonium nitrate, monoammonium phosphate, potassium chloride, gum arabic and deionized water is 190:220:70:20:500, stir until uniform, granulate in a disc granulator, pass through a 30-mesh sieve, and obtain a fertilizer granule core;

[0070] Step 2, preparing a modified starch inner coating solution, the same as in Example 1;

[0071] Step 3, forming the inner envelope:

[0072] The modified starch coating liquid is sprayed on the surface of the fertilizer particle core with a spraying thickness of 0.5 mm, and the modified starch coated fertilizer is obtained by disk granulation;

[0073] Step 4, forming the biochar outer film:

[0074] After the biochar, attapulgite, sodium carboxymethyl cellulose and vegetable oil are evenly mixed, the mass ratio of biochar, attapulgite, sodium carboxymethyl cellulose and vegetable oil is 25:25:2.5:12, and sprayed on the surface of modified starch coated fertilizer with a spraying thickness of 0.6 mm. Under blast heating and drying, a special coated controlled-release fertilizer for soil-modified and disease-resistant wheat is obtained.

[0075] Example 4

[0076] A method for preparing a soil-improving disease-resistant wheat coated controlled-release fertilizer is different from that of Example 1 only in that the preparation process of the modified starch inner coating liquid in step 2 is different.

[0077] Step 2, preparing modified starch inner coating solution:

[0078] S1. Preparation of amino starch:

[0079] Weigh corn starch (purity of corn starch ≥ 98%, water content ≤ 14%, acidity ≤ 1.8) and dimethyl sulfoxide, mix, heat to 80°C, stir thoroughly until a uniform mixed solution is formed, then drop aminosilane coupling agent solution (KH-550: deionized water mass ratio is 1:8), the mass ratio of corn starch, dimethyl sulfoxide and aminosilane coupling agent solution is 1:60:20, keep warm and stir for 1h after the dropwise addition, then cool to room temperature, discharge in anhydrous ethanol, centrifuge, wash and dry to obtain amino starch;

[0080] S2, washing, drying and crushing the seaweed to obtain seaweed powder, adding the seaweed powder to a 20% sodium carbonate solution by mass, the mass ratio of the seaweed powder to the sodium carbonate solution being 1:10, stirring at a temperature of 50° C. and a speed of 200 rpm for 6 h, cooling to room temperature, collecting the supernatant by centrifugation, and vacuum drying to obtain a seaweed extract;

[0081] S3, adding the seaweed extract to a sodium hydroxide solution with a mass fraction of 8%-16%, stirring well, then dropping 3% chloroacetic acid, the mass ratio of the seaweed extract, the chloroacetic acid solution and the sodium hydroxide solution is 1:2:10, heating to 50°C, keeping warm for 2h, then cooling to room temperature, dropping glacial acetic acid until the pH of the reaction solution is neutral, centrifuging to collect the supernatant, and vacuum drying to obtain a carboxymethylated seaweed extract;

[0082] S4. Add the amino starch into deionized water for gelatinization treatment, the gelatinization temperature is 60°C, the gelatinization time is 0.5h, and then add the carboxymethylated seaweed extract, the mass ratio of the amino starch, the carboxymethylated seaweed extract and the deionized water is 1:0.3:40, under the action of the catalyst p-toluenesulfonic acid, the addition amount is 2% of the amino starch, the temperature is raised to 80°C, and the mixture is stirred for 2h. After the reaction is completed, ammonia water is added dropwise until the pH of the reaction solution is neutral, and the temperature is lowered to room temperature to obtain a modified starch inner coating liquid.

[0083] Example 5

[0084] A method for preparing a soil-improving disease-resistant wheat coated controlled-release fertilizer is different from that of Example 1 only in that the preparation process of the modified starch inner coating liquid in step 2 is different.

[0085] Step 2, preparing modified starch inner coating solution:

[0086] S1. Preparation of amino starch:

[0087] Weigh corn starch (purity of corn starch ≥ 98%, water content ≤ 14%, acidity ≤ 1.8) and dimethyl sulfoxide, mix, heat to 90°C, stir thoroughly until a uniform mixed solution is formed, then drop aminosilane coupling agent solution (KH-550: deionized water mass ratio is 1:12), the mass ratio of corn starch, dimethyl sulfoxide and aminosilane coupling agent solution is 1:80:40, keep warm and stir for 2h after the dropwise addition, then cool to room temperature, discharge in anhydrous ethanol, centrifuge, wash and dry to obtain aminosilane;

[0088] S2, washing, drying and crushing the seaweed to obtain seaweed powder, adding the seaweed powder to a 30% sodium carbonate solution by mass, the mass ratio of the seaweed powder to the sodium carbonate solution being 1:20, stirring at a temperature of 60° C. and a speed of 300 rpm for 8 h, cooling to room temperature, collecting the supernatant by centrifugation, and vacuum drying to obtain a seaweed extract;

[0089] S3, adding the seaweed extract to a sodium hydroxide solution with a mass fraction of 16%, stirring thoroughly, then dropping chloroacetic acid with a mass fraction of 8%, the mass ratio of the seaweed extract, the chloroacetic acid solution and the sodium hydroxide solution is 1:4:20, heating to 70°C, keeping warm for 5 hours, then cooling to room temperature, dropping glacial acetic acid until the pH of the reaction solution is neutral, centrifuging to collect the supernatant, and vacuum drying to obtain a carboxymethylated seaweed extract;

[0090] S4. Add the amino starch into deionized water for gelatinization at a gelatinization temperature of 70°C for 1 hour, then add the carboxymethylated seaweed extract, the mass ratio of the amino starch, carboxymethylated seaweed extract and deionized water is 1:0.8:60, under the action of the catalyst p-toluenesulfonic acid, the added amount is 6% of the amino starch, the temperature is raised to 100°C, and the mixture is stirred for 4 hours. After the reaction is completed, ammonia water is added dropwise until the pH of the reaction solution is neutral, and the temperature is lowered to room temperature to obtain a modified starch inner coating solution.

[0091] Comparative Example 1

[0092] A method for preparing a fertilizer, which differs from Example 1 in that only the fertilizer particle core is used, and the preparation method comprises:

[0093] Weigh urea, monoammonium phosphate and potassium chloride, mix them in deionized water, add gum arabic, the mass ratio of urea, monoammonium phosphate, potassium chloride, gum arabic and deionized water is 180:210:60:15:500, stir until uniform, granulate in a disc granulator, pass through a 30-mesh sieve, and obtain a fertilizer granule core.

[0094] Comparative Example 2

[0095] A method for preparing a fertilizer, which differs from Example 1 in that no modified starch inner coating liquid is used, and the preparation method comprises:

[0096] Step 1, preparing the fertilizer granule core:

[0097] Weigh urea, monoammonium phosphate and potassium chloride, mix them in deionized water, add gum arabic, the mass ratio of urea, monoammonium phosphate, potassium chloride, gum arabic and deionized water is 180:210:60:15:500, stir until uniform, granulate in a disc granulator, pass through a 30-mesh sieve, and obtain a fertilizer granule core;

[0098] Step 2, forming the biochar outer membrane:

[0099] After the biochar, attapulgite, sodium carboxymethyl cellulose and vegetable oil are evenly mixed, the mass ratio of the biochar, attapulgite, sodium carboxymethyl cellulose and vegetable oil is 22:21:2:11, and sprayed on the surface of the fertilizer particle core with a spraying thickness of 0.3-0.6mm, and dried under blast heating to obtain the fertilizer.

[0100] Comparative Example 3

[0101] A method for preparing a fertilizer, which differs from Example 1 in that the modified starch inner coating liquid is only a mixture of seaweed extract and starch, and the remaining steps are the same as those of Example 1.

[0102] The preparation method of the modified starch inner coating liquid comprises:

[0103] S1. Wash, dry and crush the seaweed to obtain seaweed powder, add the seaweed powder to a 20% sodium carbonate solution, the mass ratio of the seaweed powder to the sodium carbonate solution is 1:10, stir at 50°C and 200rpm for 6h, cool to room temperature, collect the supernatant by centrifugation, and vacuum dry to obtain a seaweed extract;

[0104] S2. Add starch to deionized water for gelatinization at a gelatinization temperature of 60°C for a gelatinization time of 0.5 h, then add seaweed extract, raise the temperature to 80°C, keep stirring for 2 h, and cool to room temperature to obtain a modified starch inner coating solution.

[0105] Experimental example

[0106] The effects of the fertilizers prepared in different embodiments and comparative examples on wheat sheath blight and final yield were determined through field trials.

[0107] The wheat variety selected was 'Jimai 22', and the test site was selected in Handan City, Hebei Province. The area of ​​each test group was 1 mu, and the basic physical and chemical properties of the soil were: organic matter content 1.62%, alkaline nitrogen 104.8 mg / kg, available phosphorus 45.3 mg / kg, available potassium 98 mg / kg, pH 6.92. Wheat was planted on October 10, 2022 and harvested on June 16, 2023. Except for the different basal fertilizers applied, other field management measures such as sowing, irrigation, and weeding were the same for each treatment.

[0108] The test results are shown in Table 1-3.

[0109] Table 1 Control effect of the embodiments and comparative examples on wheat sheath blight

[0110]

[0111] It can be seen that compared with the comparative example, after applying the soil-improving disease-resistant wheat special coated controlled-release fertilizer according to the embodiment of the present invention, the rate of wheat sheath blight diseased plants was significantly reduced.

[0112] Table 2 Effect of Examples and Comparative Examples on Wheat Yield

[0113]

[0114] It can be seen that compared with the comparative example, after applying the soil-improving and disease-resistant wheat-specific coated controlled-release fertilizer according to the embodiment of the present invention, the wheat yield was significantly improved.

[0115] Table 3 Effect of wheat harvest period on soil nutrients and organic matter content in the examples and comparative examples

[0116]

[0117] It can be seen that compared with the comparative example, after applying the coated controlled-release fertilizer specially used for soil-improving and disease-resistant wheat according to the embodiment of the present invention, the contents of soil alkaline nitrogen, available phosphorus, quick-acting potassium and organic matter were all increased.

[0118] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily being directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0119] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a coated controlled-release fertilizer for soil-improving disease-resistant wheat. It is characterized in that The following steps are involved: Step 1, preparing the fertilizer granule core: Weigh nitrogen fertilizer, phosphate fertilizer and potash fertilizer, mix them in deionized water, add gum arabic, stir thoroughly until uniform, granulate in a disc granulator, sieve, and obtain fertilizer granule cores; Step 2, preparing modified starch inner coating solution: The amino starch is added to deionized water for gelatinization, and then the carboxymethylated seaweed extract is added. Under the action of a catalyst, the temperature is raised to 80-100°C, and the mixture is stirred for 2-4 hours. After the reaction is completed, ammonia water is added dropwise until the pH of the reaction solution is neutral, and the mixture is cooled to room temperature to obtain a modified starch inner coating solution. Step 3, forming the inner envelope: The modified starch coating liquid is sprayed on the surface of the fertilizer particle core, and the modified starch coating fertilizer is obtained by disk granulation; Step 4, forming the biochar outer membrane: The biochar, attapulgite, sodium carboxymethyl cellulose and vegetable oil are uniformly mixed, sprayed on the surface of modified starch coated fertilizer, and dried by blast heating to obtain a soil-modified disease-resistant wheat coated controlled-release fertilizer.

2. The method for preparing a soil-improving disease-resistant wheat coated controlled-release fertilizer according to claim 1, It is characterized in that In step 1, the nitrogen fertilizer is one or more of urea, ammonium nitrate, and calcium ammonium nitrate; the phosphate fertilizer is one or more of monoammonium phosphate or diammonium phosphate; and the potash fertilizer is one or more of potassium chloride or potassium sulfate.

3. The method for preparing a soil-improving disease-resistant wheat coated controlled-release fertilizer according to claim 1, It is characterized in that In the step 1, the mass ratio of nitrogen fertilizer, phosphorus fertilizer and potash fertilizer is 170-190:200-220:50-70.

4. The method for preparing a soil-improving disease-resistant wheat coated controlled-release fertilizer according to claim 1, It is characterized in that In step 2, the preparation method of amino starch comprises: Weigh corn starch and dimethyl sulfoxide, mix them, heat them to 80-90°C, stir them thoroughly until a uniform mixed solution is formed, then drop the aminosilane coupling agent solution, keep the mixture warm and stir for 1-2 hours after the dropwise addition, then cool it to room temperature, discharge it into anhydrous ethanol, centrifuge, wash and dry it to obtain amino starch.

5. The method for preparing a soil-improving disease-resistant wheat coated controlled-release fertilizer according to claim 1, It is characterized in that In the preparation process of the amino starch, the mass ratio of corn starch, dimethyl sulfoxide and aminosilane coupling agent solution is 1:60-80:20-40; the aminosilane coupling agent solution is obtained by mixing KH-550 and deionized water in a mass ratio of 1:8-12.

6. The method for preparing a soil-improving disease-resistant wheat coated controlled-release fertilizer according to claim 1, It is characterized in that In step 2, the method for preparing the carboxymethylated seaweed extract comprises: S1. Wash, dry and crush the seaweed to obtain seaweed powder, add the seaweed powder into a sodium carbonate solution, stir at a temperature of 50-60° C. and a speed of 200-300 rpm for 6-8 hours, cool to room temperature, collect the supernatant by centrifugation, and vacuum dry to obtain a seaweed extract; S2. Add the seaweed extract to the sodium hydroxide solution, stir well, then add chloroacetic acid solution, raise the temperature to 50-70°C, keep warm for 2-5 hours, then cool to room temperature, add glacial acetic acid until the pH of the reaction solution is neutral, collect the supernatant by centrifugation, and vacuum dry to obtain the carboxymethylated seaweed extract.

7. The method for preparing a soil-improving disease-resistant wheat coated controlled-release fertilizer according to claim 6, It is characterized in that In the S1, the mass fraction of the sodium carbonate solution is 20%-30%, and the mass ratio of the seaweed powder to the sodium carbonate solution is 1:10-20; in the S2, the mass fraction of the sodium hydroxide solution is 8%-16%, the mass fraction of the chloroacetic acid solution is 3%-8%, and the mass ratio of the seaweed extract, the chloroacetic acid solution and the sodium hydroxide solution is 1:2-4:10-20.

8. The method for preparing a soil-improving disease-resistant wheat coated controlled-release fertilizer according to claim 1, It is characterized in that In the step 2, the mass ratio of the amino starch, the carboxymethylated seaweed extract and the deionized water is 1:0.3-0.8:40-60; the catalyst is p-toluenesulfonic acid, and the added amount is 2%-6% of the amino starch.

9. The method for preparing a soil-improving disease-resistant wheat coated controlled-release fertilizer according to claim 1, It is characterized in that In the step 4, the mass ratio of biochar, attapulgite, sodium carboxymethyl cellulose and vegetable oil is 20-25:20-25:2-2.5:10-12.

10. A coated controlled-release fertilizer for soil-improving and disease-resistant wheat. It is characterized in that The preparation method according to claim 1 is used for preparation.

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