Water-soluble fertilizer prepared using seaweed and preparation method thereof

Abstract

The present invention discloses a water-soluble fertilizer prepared from seaweed and a preparation method thereof, belonging to the technical field of fertilizers. The present invention prepares a seaweed extract by adopting an optimized chemical extraction method, combining a three-stage gradient temperature alkaline hydrolysis process with a two-stage acidification and room-temperature acid hydrolysis process. Compared with traditional chemical extraction methods, the present invention not only retains the effective ingredients in the seaweed but also improves the extraction efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of fertilizers, and in particular relates to a water-soluble fertilizer prepared by utilizing seaweed and a preparation method thereof. Background Art

[0002] Seaweed fertilizer uses fast-growing large brown algae in the ocean as raw material and extracts beneficial components through chemical, physical, or biological techniques to create fertilizer. Applying this fertilizer to plants provides essential nutrients, promoting plant growth and development, increasing crop yields, and improving the quality of agricultural products. As a natural organic fertilizer, seaweed fertilizer's effectiveness stems from a range of active substances it contains, such as cytokines, plant hormones (such as auxins, gibberellins, abscisic acid, and ethylene), betaine, and polyamines.

[0003] In the production process of seaweed fertilizer, the technical challenges mainly focus on how to effectively degrade the main components of seaweed, such as cellulose, pectin and protein, while ensuring the maximum preservation of the original macroelements, trace elements, gibberellins, cytokinin-like substances, polyphenol compounds and components with antibacterial properties in the seaweed. This process requires precise control to ensure that the activity and concentration of these beneficial ingredients are not destroyed, thereby ensuring the effectiveness and quality of the seaweed fertilizer. At present, the production process of seaweed fertilizer mainly adopts physical crushing and chemical extraction methods, which cause a lot of damage to the effective active ingredients in the seaweed, seriously affecting the effect of the subsequent processing and fertilizer production. The biological enzymatic hydrolysis method and microbial hydrolysis method usually take longer to complete, which affects the widespread implementation of this method in industry. Therefore, how to improve the extraction efficiency while ensuring the effectiveness of seaweed water-soluble fertilizer is a current technical problem. Summary of the Invention

[0004] In response to the above technical problems, the present invention provides a water-soluble fertilizer prepared using seaweed and a preparation method thereof. An optimized chemical extraction method is adopted in the preparation process of the seaweed extract to reduce the destruction of effective ingredients caused by chemical extraction while improving the extraction efficiency.

[0005] The present invention provides a water-soluble fertilizer prepared by using seaweed, characterized in that it comprises the following components, calculated by weight: 30-40 parts of seaweed extract, 15-20 parts of water-soluble humic acid, 7-10 parts of potassium chloride, 7-10 parts of magnesium sulfate, 3-5 parts of urea, 3-7 parts of a chelating agent, and 2-8 parts of amino acids.

[0006] Preferably, the present invention provides a water-soluble fertilizer prepared using seaweed, characterized in that it comprises the following components, in parts by weight: 40 parts of seaweed extract, 20 parts of water-soluble humic acid, 10 parts of potassium chloride, 10 parts of magnesium sulfate, 5 parts of urea, 7 parts of chelating agent, and 8 parts of amino acids.

[0007] Among them, the seaweed extract was prepared by the following preparation method: S01 take fresh seaweed, according to the material-water ratio of mass ratio of 1: 1 was added deionized water, ground to make a seaweed slurry, refrigerated standby;

[0008] S02. Add the seaweed slurry described in step S01 to an alkaline hydrolysis reactor at normal pressure, add potassium hydroxide solution to adjust the pH to 8.0-8.5, open the steam valve, heat the seaweed slurry to 50-55°C, maintain and stir for 10 minutes, then heat the seaweed slurry to 60-65°C, maintain and stir for 10 minutes, and then heat the seaweed slurry to 70-75°C, maintain and stir for 30 minutes. Remove the alkaline hydrolysis product from the alkaline hydrolysis reactor and filter to obtain an alkaline hydrolysis filtrate and an alkaline hydrolysis residue.

[0009] S03. The alkaline hydrolysis residue was added to the acid hydrolysis reactor, and deionized water was added, stirred at room temperature and sulfuric acid solution was added to adjust the pH value of the system to 3.5-4. After stirring at room temperature for 30 minutes, sulfuric acid solution was continued to be added to adjust the pH to 2.5-3, stirred at room temperature for 30 minutes, and the acid hydrolysis product was removed from the acid hydrolysis reactor and filtered to obtain an acid hydrolysis filtrate and an acid hydrolysis residue;

[0010] S04. The alkaline hydrolysis filtrate of step S02 and the acid hydrolysis filtrate of step S03 are mixed to obtain a mixture, the pH of the mixture is adjusted to 6.8-7.8, and the mixture is stirred to obtain the seaweed extract.

[0011] The fresh seaweed includes one or more of brown algae, sargassum, kelp and giant kelp.

[0012] The chelating agent includes glucuronic acid and sodium tripolyphosphate.

[0013] The amino acids include one or more of arginine, serine, methionine, leucine and glutamic acid.

[0014] Preferably, in step S03, deionized water is added, and the ratio of the alkaline hydrolysis residue to the deionized water is 1:1 in parts by weight.

[0015] Preferably, the mass ratio of the alkaline hydrolysis filtrate to the acid hydrolysis filtrate in step S04 is 1:1.

[0016] Preferably, in step S04, the pH of the mixture is adjusted to 7.0.

[0017] The present invention also provides a method for preparing a water-soluble fertilizer using seaweed, which is characterized in that the seaweed extract, water-soluble humic acid, potassium chloride, magnesium sulfate, urea, a chelating agent, and amino acids are mixed.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects: The present invention adopts a chemical extraction method of alkaline hydrolysis followed by acid hydrolysis, which, through an optimized chemical extraction process, reduces the destruction of effective ingredients and reduced extraction efficiency caused by traditional chemical extraction. A three-stage gradient temperature increase process is used during the alkaline hydrolysis process to provide sufficient swelling of the seaweed cell walls, preventing damage to the seaweed cell walls caused by direct alkaline hydrolysis at elevated temperatures. Simultaneously, room-temperature acid hydrolysis is used to reduce the acid hydrolysis pH of the alkaline hydrolysis residue in two stages, further ensuring the effective ingredients in the extracted residue and the purity of the extraction. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments; the technical features designed in the different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] Example 1

[0021] A water-soluble fertilizer prepared from seaweed, the fertilizer containing the following components: in parts by weight, including the following components: 40 parts of seaweed extract, 20 parts of water-soluble humic acid, 10 parts of potassium chloride, 10 parts of magnesium sulfate, 5 parts of urea, 7 parts in total of glucuronic acid and sodium tripolyphosphate, and 8 parts of glutamic acid;

[0022] The preparation method of seaweed extract is as follows:

[0023] S01 take fresh brown algae, press the material-water ratio mass ratio of 1: 1 ratio of deionized water, grind to make seaweed slurry, refrigerate and set aside;

[0024] S02. Add the seaweed slurry described in step S01 to an alkaline hydrolysis reactor at normal pressure, add potassium hydroxide solution to adjust the pH to 8.0, open the steam valve, heat the seaweed slurry to 55°C, maintain the temperature and stir for 10 minutes, then heat the seaweed slurry to 65°C, maintain the temperature and stir for 10 minutes, and then heat the seaweed slurry to 75°C, maintain the temperature and stir for 30 minutes. Remove the alkaline hydrolysis product from the alkaline hydrolysis reactor and filter it to obtain an alkaline hydrolysis filtrate and an alkaline hydrolysis residue.

[0025] S03. The alkaline hydrolysis residue was added to the acid hydrolysis reactor, and an equal mass of deionized water was added to the alkaline hydrolysis residue, stirred at room temperature and sulfuric acid solution was added to adjust the pH value of the system to 4. After stirring at room temperature for 30 minutes, sulfuric acid solution was continued to be added to adjust the pH to 3, stirred at room temperature for 30 minutes, and the acid hydrolysis product was removed from the acid hydrolysis reactor and filtered to obtain an acid hydrolysis filtrate and an acid hydrolysis residue;

[0026] S04. The alkaline hydrolysis filtrate of step S02 and the acid hydrolysis filtrate of step S03 are mixed in a mass ratio of 1:1 to obtain a mixture, the pH of the mixture is adjusted to 7, and the mixture is stirred to obtain the seaweed extract.

[0027] The preparation method of the water-soluble fertilizer prepared by using seaweed is to uniformly stir the components of the above fertilizer according to weight parts at room temperature.

[0028] Example 2

[0029] A water-soluble fertilizer prepared from seaweed, the fertilizer containing the following components: in parts by weight, including the following components: 40 parts of seaweed extract, 20 parts of water-soluble humic acid, 10 parts of potassium chloride, 10 parts of magnesium sulfate, 5 parts of urea, 7 parts in total of glucuronic acid and sodium tripolyphosphate, and 8 parts of glutamic acid;

[0030] The preparation method of seaweed extract is as follows:

[0031] S01 take fresh brown algae, press the material-water ratio mass ratio of 1: 1 ratio of deionized water, grind to make seaweed slurry, refrigerate and set aside;

[0032] S02. Add the seaweed slurry described in step S01 to an alkaline hydrolysis reactor at normal pressure, add potassium hydroxide solution to adjust the pH to 8.5, open the steam valve, heat the seaweed slurry to 50°C, maintain the temperature and stir for 10 minutes, then heat the seaweed slurry to 60°C, maintain the temperature and stir for 10 minutes, then heat the seaweed slurry to 75°C, maintain the temperature and stir for 30 minutes, remove the alkaline hydrolysis product from the alkaline hydrolysis reactor and filter to obtain an alkaline hydrolysis filtrate and an alkaline hydrolysis residue;

[0033] S03. The alkaline hydrolysis residue was added to the acid hydrolysis reactor, and the same mass of deionized water as the alkaline hydrolysis residue was added, stirred at room temperature and sulfuric acid solution was added to adjust the pH value of the system to 4. After stirring at room temperature for 30 minutes, sulfuric acid solution was continued to be added to adjust the pH to 2.5, stirred at room temperature for 30 minutes, and the acid hydrolysis product was removed from the acid hydrolysis reactor and filtered to obtain an acid hydrolysis filtrate and an acid hydrolysis residue;

[0034] S04. The alkaline hydrolysis filtrate of step S02 and the acid hydrolysis filtrate of step S03 are mixed in a mass ratio of 1:1 to obtain a mixture, the pH of the mixture is adjusted to 7, and the mixture is stirred to obtain the seaweed extract.

[0035] The preparation method of the water-soluble fertilizer prepared by using seaweed is to uniformly stir the components of the above fertilizer according to weight parts at room temperature.

[0036] Comparative Example 1

[0037] A water-soluble fertilizer prepared from seaweed, the fertilizer containing the following components: in parts by weight, including the following components: 40 parts of seaweed extract, 20 parts of water-soluble humic acid, 10 parts of potassium chloride, 10 parts of magnesium sulfate, 5 parts of urea, 7 parts in total of glucuronic acid and sodium tripolyphosphate, and 8 parts of glutamic acid;

[0038] The preparation method of seaweed extract is as follows:

[0039] S01 take fresh brown algae, press the material-water ratio mass ratio of 1: 1 ratio of deionized water, grind to make seaweed slurry, refrigerate and set aside;

[0040] S02. Add the seaweed slurry described in step S01 to an alkaline hydrolysis reactor at atmospheric pressure, add potassium hydroxide solution to adjust the pH to 8.0, open the steam valve to heat the seaweed slurry to 75°C, maintain the temperature and stir for 50 minutes, remove the alkaline hydrolysis product from the alkaline hydrolysis reactor and filter to obtain an alkaline hydrolysis filtrate and an alkaline hydrolysis residue;

[0041] S03. The alkaline hydrolysis residue was added to the acid hydrolysis reactor, and an equal mass of deionized water was added to the alkaline hydrolysis residue, stirred at room temperature and sulfuric acid solution was added to adjust the pH value of the system to 4. After stirring at room temperature for 30 minutes, sulfuric acid solution was continued to be added to adjust the pH to 3, stirred at room temperature for 30 minutes, and the acid hydrolysis product was removed from the acid hydrolysis reactor and filtered to obtain an acid hydrolysis filtrate and an acid hydrolysis residue;

[0042] S04. The alkaline hydrolysis filtrate of step S02 and the acid hydrolysis filtrate of step S03 are mixed in a mass ratio of 1:1 to obtain a mixture, the pH of the mixture is adjusted to 7, and the mixture is stirred to obtain the seaweed extract.

[0043] The preparation method of the water-soluble fertilizer prepared by using seaweed is to uniformly stir the components of the above fertilizer according to weight parts at room temperature.

[0044] Comparative Example 2

[0045] A water-soluble fertilizer prepared from seaweed, the fertilizer containing the following components: in parts by weight, including the following components: 40 parts of seaweed extract, 20 parts of water-soluble humic acid, 10 parts of potassium chloride, 10 parts of magnesium sulfate, 5 parts of urea, 7 parts in total of glucuronic acid and sodium tripolyphosphate, and 8 parts of glutamic acid;

[0046] The preparation method of seaweed extract is as follows:

[0047] S01 take fresh brown algae, press the material-water ratio mass ratio of 1: 1 ratio of deionized water, grind to make seaweed slurry, refrigerate and set aside;

[0048] S02. Add the seaweed slurry described in step S01 to an alkaline hydrolysis reactor at normal pressure, add potassium hydroxide solution to adjust the pH to 8.0, open the steam valve, heat the seaweed slurry to 55°C, maintain the temperature and stir for 10 minutes, then heat the seaweed slurry to 65°C, maintain the temperature and stir for 10 minutes, and then heat the seaweed slurry to 75°C, maintain the temperature and stir for 30 minutes. Remove the alkaline hydrolysis product from the alkaline hydrolysis reactor and filter it to obtain an alkaline hydrolysis filtrate and an alkaline hydrolysis residue.

[0049] S03. The alkaline hydrolysis residue was added to the acid hydrolysis reactor, and the same mass of deionized water as the alkaline hydrolysis residue was added, stirred at room temperature and sulfuric acid solution was added to adjust the pH value of the system to 3, stirred at room temperature for 60 minutes, and the acid hydrolysis product was removed from the acid hydrolysis reactor and filtered to obtain an acid hydrolysis filtrate and acid hydrolysis residue;

[0050] S04. The alkaline hydrolysis filtrate of step S02 and the acid hydrolysis filtrate of step S03 are mixed in a mass ratio of 1:1 to obtain a mixture, the pH of the mixture is adjusted to 7, and the mixture is stirred to obtain the seaweed extract.

[0051] The preparation method of the water-soluble fertilizer prepared by using seaweed is to uniformly stir the components of the above fertilizer according to weight parts at room temperature.

[0052] Comparative Example 3

[0053] A water-soluble fertilizer prepared from seaweed, the fertilizer containing the following components: in parts by weight, including the following components: 40 parts of seaweed extract, 20 parts of water-soluble humic acid, 10 parts of potassium chloride, 10 parts of magnesium sulfate, 5 parts of urea, 7 parts in total of glucuronic acid and sodium tripolyphosphate, and 8 parts of glutamic acid;

[0054] The preparation method of seaweed extract is as follows:

[0055] S01 take fresh brown algae, press the material-water ratio mass ratio of 1: 1 ratio of deionized water, grind to make seaweed slurry, refrigerate and set aside;

[0056] S02. Add the seaweed slurry described in step S01 to an alkaline hydrolysis reactor at normal pressure, add potassium hydroxide solution to adjust the pH to 8.0, open the steam valve, heat the seaweed slurry to 55°C, maintain the temperature with stirring for 20 minutes, then heat the seaweed slurry to 75°C, maintain the temperature with stirring for 30 minutes, remove the alkaline hydrolysis product from the alkaline hydrolysis reactor, and filter to obtain an alkaline hydrolysis filtrate and an alkaline hydrolysis residue;

[0057] S03. The alkaline hydrolysis residue was added to the acid hydrolysis reactor, and an equal mass of deionized water was added to the alkaline hydrolysis residue, stirred at room temperature and sulfuric acid solution was added to adjust the pH value of the system to 4. After stirring at room temperature for 30 minutes, sulfuric acid solution was continued to be added to adjust the pH to 3, stirred at room temperature for 30 minutes, and the acid hydrolysis product was removed from the acid hydrolysis reactor and filtered to obtain an acid hydrolysis filtrate and an acid hydrolysis residue;

[0058] S04. The alkaline hydrolysis filtrate of step S02 and the acid hydrolysis filtrate of step S03 are mixed in a mass ratio of 1:1 to obtain a mixture, the pH of the mixture is adjusted to 7, and the mixture is stirred to obtain the seaweed extract.

[0059] The preparation method of the water-soluble fertilizer prepared by using seaweed is to uniformly stir the components of the above fertilizer according to weight parts at room temperature.

[0060] Comparative Example 4

[0061] A water-soluble fertilizer prepared from seaweed, the fertilizer containing the following components: in parts by weight, including the following components: 40 parts of seaweed extract, 20 parts of water-soluble humic acid, 10 parts of potassium chloride, 10 parts of magnesium sulfate, 5 parts of urea, 7 parts in total of glucuronic acid and sodium tripolyphosphate, and 8 parts of glutamic acid;

[0062] The preparation method of seaweed extract is as follows:

[0063] S01 take fresh brown algae, press the material-water ratio mass ratio of 1: 1 ratio of deionized water, grind to make seaweed slurry, refrigerate and set aside;

[0064] S02. Add the seaweed slurry described in step S01 to an alkaline hydrolysis reactor at atmospheric pressure, add potassium hydroxide solution to adjust the pH to 8.0, open the steam valve to heat the seaweed slurry to 75°C, maintain the temperature and stir for 50 minutes, remove the alkaline hydrolysis product from the alkaline hydrolysis reactor and filter to obtain an alkaline hydrolysis filtrate and an alkaline hydrolysis residue;

[0065] S03. The alkaline hydrolysis residue was added to the acid hydrolysis reactor, and the same mass of deionized water as the alkaline hydrolysis residue was added, stirred at room temperature and sulfuric acid solution was added to adjust the pH value of the system to 3, stirred at room temperature for 60 minutes, and the acid hydrolysis product was removed from the acid hydrolysis reactor and filtered to obtain an acid hydrolysis filtrate and acid hydrolysis residue;

[0066] S04. The alkaline hydrolysis filtrate of step S02 and the acid hydrolysis filtrate of step S03 are mixed in a mass ratio of 1:1 to obtain a mixture, the pH of the mixture is adjusted to 7, and the mixture is stirred to obtain the seaweed extract.

[0067] The preparation method of the water-soluble fertilizer prepared by using seaweed is to uniformly stir the components of the above fertilizer according to weight parts at room temperature.

[0068] The seaweed extracts prepared in Examples 1-2 and Comparative Examples 1-4 were respectively taken to determine the contents of alginic acid, seaweed oligosaccharides, gibberellins and indoleacetic acid. The results are shown in Table 1.

[0069] Table 1 Determination results of the content of each component in seaweed extract

[0070] Seaweed extract alginic acid Seaweed oligosaccharides / ppm Gibberellic acid / ppm Indoleacetic acid / ppm Example 1 2.4% 556 356 365 Example 2 2.5% 494 321 359 Comparative Example 1 1.8% 368 192 281 Comparative Example 2 1.9% 395 186 310 Comparative Example 3 2.0% 385 232 289 Comparative Example 4 1.8% 336 154 221

[0071] The water-soluble fertilizers of Examples 1-2 and Comparative Examples 1-4 were used to conduct fertilizer efficiency tests. The test location was Fushan, Yantai.

[0072] The test crop was strawberry. Six treatments of the present invention's water-soluble seaweed fertilizer (A1, A2, B1, B2, B3, B4) were set up. A1, A2, B1, B2, B3, and B4 were prepared from Examples 1-2 and Comparative Examples 1-4, respectively. The above treatments were repeated three times and randomly arranged. Strawberries were planted in single-ridge double-row cultivation with a large row spacing of 75 cm, a small row spacing of 30 cm, and a plant spacing of 20 cm. Approximately 100 plants were planted per ridge. The fertilizer was diluted 400-500 times with water and irrigated the roots. Application was made every 10 days from the seedling stage for a total of three applications.

[0073] The root growth of strawberries is shown in Table 2. As can be seen from Table 2, the root growth of strawberries treated with the water-soluble seaweed fertilizer according to the present invention was significantly different from that of the control. This indicates that applying the water-soluble seaweed fertilizer according to the present invention can increase the growth of crop roots.

[0074] Table 2 Root development of strawberry

[0075] deal with Longest root length / cm Root fresh weight / g A1 15.1 2.7 A2 16.8 3.0 B1 13.5 1.7 B2 14.0 2.0 B3 12.6 2.3 B4 11.8 1.9

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A water-soluble fertilizer prepared using seaweed, characterized in that: The composition comprises the following components in parts by weight: 30-40 parts of seaweed extract, 15-20 parts of water-soluble humic acid, 7-10 parts of potassium chloride, 7-10 parts of magnesium sulfate, 3-5 parts of urea, 3-7 parts of chelating agent, and 2-8 parts of amino acid; The seaweed extract is prepared by the following preparation method: S01 take fresh seaweed, press the material-water ratio mass ratio of 1: 1 ratio of deionized water, grind to make seaweed slurry, refrigerate and set aside; S02. Adding the seaweed slurry described in step S01 to an alkaline hydrolysis reactor at normal pressure, adding potassium hydroxide solution to adjust the pH to 8.0-8.5, opening the steam valve to heat the seaweed slurry to 50-55°C, maintaining the temperature with stirring for 10 minutes, then heating the seaweed slurry to 60-65°C, maintaining the temperature with stirring for 10 minutes, and further heating the seaweed slurry to 70-75°C, maintaining the temperature with stirring for 30 minutes, removing the alkaline hydrolysis product from the alkaline hydrolysis reactor and filtering to obtain an alkaline hydrolysis filtrate and an alkaline hydrolysis residue; S03. The alkaline hydrolysis residue was added to the acid hydrolysis reactor, and deionized water was added, stirred at room temperature and sulfuric acid solution was added to adjust the pH value of the system to 3.5-4. After stirring at room temperature for 30 minutes, sulfuric acid solution was continued to be added to adjust the pH to 2.5-3, stirred at room temperature for 30 minutes, and the acid hydrolysis product was removed from the acid hydrolysis reactor and filtered to obtain an acid hydrolysis filtrate and an acid hydrolysis residue; S04. The alkaline hydrolysis filtrate of step S02 and the acid hydrolysis filtrate of step S03 are mixed to obtain a mixture, the pH of the mixture is adjusted to 6.8-7.8, and the mixture is stirred to obtain the seaweed extract; The chelating agent includes glucuronic acid and sodium tripolyphosphate.

2. The water-soluble fertilizer prepared from seaweed according to claim 1, wherein The fresh seaweed includes one or more of brown algae, sargassum, kelp and giant kelp.

3. The water-soluble fertilizer prepared by utilizing seaweed according to claim 1, characterized in that: The preparation comprises the following components in parts by weight: 40 parts of seaweed extract, 20 parts of water-soluble humic acid, 10 parts of potassium chloride, 10 parts of magnesium sulfate, 5 parts of urea, 7 parts of chelating agent and 8 parts of amino acid.

4. The water-soluble fertilizer prepared by utilizing seaweed according to claim 1, characterized in that: The amino acids include one or more of arginine, serine, methionine, leucine and glutamic acid.

5. The water-soluble fertilizer prepared by utilizing seaweed according to claim 1, characterized in that: Deionized water is added in step S03, and the ratio of the alkaline hydrolysis residue to the deionized water is 1:1 in parts by weight.

6. The water-soluble fertilizer prepared by utilizing seaweed according to claim 1, characterized in that: The mass ratio of the alkaline hydrolysis filtrate to the acid hydrolysis filtrate in step S04 is 1:

1.

7. The water-soluble fertilizer prepared by using seaweed according to claim 1, characterized in that: In step S04, the pH of the mixture is adjusted to 7.

0.

8. The method for preparing a water-soluble fertilizer using seaweed according to any one of claims 1 to 7, wherein: The seaweed extract, water-soluble humic acid, potassium chloride, magnesium sulfate, urea, chelating agent and amino acid are mixed.