A water-soluble fertilizer containing amino acids and its preparation method

Abstract

This invention relates to an amino acid-containing water-soluble fertilizer and its preparation method. The amino acid-containing water-soluble fertilizer includes the following steps: (1) crushing waste protein raw materials, adding water and a compound enzyme, mixing, enzymatically hydrolyzing and inactivating the enzyme to obtain an enzymatic hydrolysis product; (2) inoculating the enzymatic hydrolysis product with Candida utilis and Pseudomonas aeruginosa for fermentation, filtering, and obtaining a fermentation filtrate; (3) adding plant growth regulators, urea, potassium dihydrogen phosphate, potassium sulfate, ferrous sulfate, and zinc sulfate to the fermentation filtrate to obtain the amino acid-containing water-soluble fertilizer. In this invention, a compound enzyme composed of proteases is first used for enzymatic hydrolysis, and then Candida utilis and Pseudomonas aeruginosa are used for fermentation, which can increase the content of free amino acids in the fermentation filtrate, thereby improving the effect of the amino acid-containing water-soluble fertilizer.

Description

Technical Field

[0001] This invention belongs to the field of fertilizer preparation technology, specifically relating to an amino acid-containing water-soluble fertilizer and its preparation method. Background Technology

[0002] Amino acid-containing water-soluble fertilizers are highly efficient liquid or solid fertilizers with amino acids as the main active ingredient. They can quickly supplement crop nutrition through foliar spraying, drip irrigation, or fertigation. Amino acids are the basic building blocks of proteins, which can be directly absorbed and utilized by plants, promoting photosynthesis, enhancing stress resistance, and improving crop quality. Their raw materials are widely available, including animal and plant proteins decomposed through hydrolysis or fermentation. However, if the selection of microbial strains is inappropriate or the fermentation process is not strictly controlled, harmful byproducts (such as ammonia and hydrogen sulfide) may be produced, leading to a decrease in the effectiveness of amino acid-containing water-soluble fertilizers. Summary of the Invention

[0003] In view of this, a water-soluble fertilizer containing amino acids and its preparation method are proposed to solve the above problems.

[0004] A method for preparing an amino acid-containing water-soluble fertilizer includes the following steps:

[0005] (1) The waste protein raw material is crushed, then water and compound enzyme are added and mixed, and the enzyme is hydrolyzed and inactivated to obtain the enzymatic hydrolysis product; wherein the compound enzyme is a combination of two or more of neutral protease, acidic protease, trypsin and papain.

[0006] (2) Inoculate the inoculated Candida utilis and Pseudomonas aeruginosa into the enzymatic hydrolysate for fermentation, filter, and obtain fermentation filtrate;

[0007] (3) Plant growth regulators, urea, potassium dihydrogen phosphate, potassium sulfate, ferrous sulfate and zinc sulfate are added to the fermentation filtrate to prepare the amino acid-containing water-soluble fertilizer;

[0008] The plant growth regulator is at least one of chlorogenic acid, amino oligosaccharide, phenylpeptide amino acid, calcium cyclohexane, and methyl jasmonate.

[0009] Further, in step (1), the mass ratio of the waste protein raw material, water and compound enzyme is 1:4-6:0.01-0.1; the raw material of the waste protein raw material is either plant protein or animal protein.

[0010] Further, in step (1), the complex enzyme is trypsin, papain, neutral protease or neutral protease or acidic protease with a mass ratio of 2.5-3.3:1.6-2.3:0.5-1.5.

[0011] Further, in step (1), the enzymatic hydrolysis is carried out under the conditions of pH 2-9 and 30-60℃ for 5-30 hours.

[0012] Further, in step (2), the inoculum amount of *Candida utilis* is 1-3 wt%, and the viable count is (1-5) × 10⁻⁶. 8 CFU / ml; the inoculum amount of *Pseudomonas aeruginosa* is 1-3 wt%, and the viable count is (3-5) × 10⁻⁶. 9 CFU / mL.

[0013] Further, in step (2), the fermentation is carried out under aerobic conditions at pH 5-6 and 25-35°C for 30-40 hours.

[0014] Further, in step (3), the plant growth regulator is an amino oligosaccharide, phenylpeptide amino acid, methyl jasmonate in a mass ratio of 1:3-5:1-2 or chlorogenic acid, calcium cyclohexane, methyl jasmonate in a mass ratio of 0.4-0.9:3-5:1.5-2.

[0015] Further, in step (3), based on the mass of the waste protein raw materials, the amount of plant growth regulator added is 0.05%-0.12%, the amount of urea added is 8%-12%, the amount of potassium dihydrogen phosphate added is 3%-7%, the amount of potassium sulfate added is 2%-4%, the amount of ferrous sulfate added is 0.3%-0.7%, and the amount of zinc sulfate added is 0.2%-0.4%.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] In this invention, a complex enzyme composed of proteases is first used for enzymatic hydrolysis, and then Candida utilis and Pseudomonas aeruginosa are used for fermentation. This can increase the content of free amino acids and polypeptides in the fermentation filtrate, and at the same time produce a variety of antibacterial substances, which can inhibit the growth of plant pathogens and thus enhance the plant's disease resistance.

[0018] Adding plant growth regulators can promote plant growth by inhibiting the growth of lateral buds, improving root vitality, and preventing high-temperature stress. Simultaneously, plant growth regulators work synergistically with other nutrients to further optimize nutrient absorption and metabolism, thereby improving the overall growth efficiency of crops. Adding raw materials such as urea, ferrous sulfate, zinc sulfate, and potassium dihydrogen phosphate can supplement the N, P, and K elements in amino acid-containing water-soluble fertilizers, which is beneficial for improving the effectiveness of these fertilizers. Detailed Implementation

[0019] This invention provides a plant-based anti-aging composition, its preparation method, and its application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0020] Unless otherwise specified, the experimental methods used in the examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0021] The enzyme activities of neutral protease, acidic protease, trypsin, and papain are not less than 5 × 10⁻⁶. 4 U / g;

[0022] Candida utilis was purchased from the China General Microbiological Culture Collection Center, accession number CGMCC.No.2.2878;

[0023] The *Pseudomonas aeruginosa* was purchased from the China General Microbiological Culture Collection Center, with accession number CGMCC.No.1.16088;

[0024] Bacillus subtilis was purchased from the China General Microbiological Culture Collection Center, with accession number CGMCC: NO.20824;

[0025] The brewing yeast was purchased from Angel Yeast Co., Ltd.

[0026] Chlorogenic acid was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; CAS: 327-97-9;

[0027] The amino oligosaccharide was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; CAS: 9012-76-4;

[0028] Phenyptamine amino acid was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; CAS: 4727-29-1;

[0029] Calcium cyclohexane was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; CAS: 127277-53-6;

[0030] Methyl jasmonate was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; CAS: 1211-29-6;

[0031] The waste protein raw material used in this invention is meat processing scraps.

[0032] Example 1

[0033] A method for preparing an amino acid-containing water-soluble fertilizer includes the following steps:

[0034] (1) The meat processing scraps are crushed, and the meat processing scraps and water are mixed to obtain the reaction substrate; the raw materials of the compound enzyme are added to the reaction substrate in steps to carry out the reaction. First, papain and neutral protease are added to the reaction substrate, and the enzyme is hydrolyzed for 3.5 h under aerobic conditions at pH 7 and temperature 50℃ to inactivate the enzyme and obtain enzymatic hydrolysis product 1; then the pH of enzymatic hydrolysis product 1 is adjusted to 8.1 with an alkali agent, and trypsin is added. The enzyme is hydrolyzed for 3 h under conditions at temperature 37℃ to inactivate the enzyme and obtain enzymatic hydrolysis product 2; wherein, the mass ratio of the meat processing scraps, water and compound enzyme is 1:5:0.05; the compound enzyme is trypsin, papain and neutral protease in a mass ratio of 3:2:1.

[0035] (2) Inoculate Candida utilis and Pseudomonas aeruginosa into enzymatic hydrolysate 2, and ferment under aerobic conditions at pH 5.5 and 30℃ for 30-40 h. Filter to obtain fermentation filtrate; wherein the inoculation amount of Candida utilis is 2 wt%, and the viable cell count is 3 × 10⁻⁶. 8 CFU / ml; the inoculum amount of *Pseudomonas aeruginosa* was 2 wt%, and the viable count was 4 × 10⁻⁶. 9 CFU / mL;

[0036] (3) Based on the mass of waste protein raw materials, 0.08% of plant growth regulator, 10% urea, 5% potassium dihydrogen phosphate, 3% potassium sulfate, 0.5% ferrous sulfate and 0.3% zinc sulfate are added to the fermentation filtrate to prepare the amino acid-containing water-soluble fertilizer.

[0037] The plant growth regulator is chlorogenic acid, calcium cyclohexane, and methyl jasmonate in a mass ratio of 0.7:4:1.8.

[0038] Example 2

[0039] A method for preparing an amino acid-containing water-soluble fertilizer includes the following steps:

[0040] (1) The meat processing scraps are crushed, and the meat processing scraps and water are mixed to obtain the reaction substrate. The raw materials of the compound enzyme are added to the reaction substrate in steps to carry out the reaction. First, papain and neutral protease are added to the reaction substrate, and the enzyme is hydrolyzed for 3.5 h under aerobic conditions at pH 7 and temperature 50℃ to inactivate the enzyme and obtain enzymatic hydrolysis product 1. Then, the pH of enzymatic hydrolysis product 1 is adjusted to 8.1 with an alkali agent, and trypsin is added. The enzyme is hydrolyzed for 3 h under conditions at temperature 37℃ to inactivate the enzyme and obtain enzymatic hydrolysis product 2. The mass ratio of the meat processing scraps, water and compound enzyme is 1:4:0.01. The compound enzyme is trypsin, papain and neutral protease with a mass ratio of 2.5:1.6:0.5.

[0041] (2) Inoculate Candida utilis and Pseudomonas aeruginosa into enzymatic hydrolysate 2, and ferment under aerobic conditions at pH 5 and 25℃ for 30-40 h. Filter to obtain fermentation filtrate; wherein the inoculation amount of Candida utilis is 1 wt%, and the viable cell count is 1 × 10⁻⁶. 8 CFU / ml; the inoculum amount of *Pseudomonas aeruginosa* was 1 wt%, and the viable count was 3 × 10⁻⁶. 9 CFU / mL;

[0042] (3) Based on the mass of waste protein raw materials, 0.05% of plant growth regulator, 8% urea, 3% potassium dihydrogen phosphate, 2% potassium sulfate, 0.3% ferrous sulfate and 0.2% zinc sulfate are added to the fermentation filtrate to prepare the amino acid-containing water-soluble fertilizer.

[0043] The plant growth regulator is chlorogenic acid, calcium cyclohexane, and methyl jasmonate in a mass ratio of 0.4:3:1.5.

[0044] Example 3

[0045] A method for preparing an amino acid-containing water-soluble fertilizer includes the following steps:

[0046] (1) The meat processing scraps are crushed, and the meat processing scraps and water are mixed to obtain the reaction substrate. The raw materials of the compound enzyme are added to the reaction substrate in steps to carry out the reaction. First, papain and neutral protease are added to the reaction substrate, and the enzyme is hydrolyzed for 3-4 hours under aerobic conditions at pH 7 and temperature 50℃ to inactivate the enzyme and obtain enzymatic hydrolysis product 1. Then, the pH of enzymatic hydrolysis product 1 is adjusted to 8.1 with an alkali agent, and trypsin is added. The enzyme is hydrolyzed for 2-4 hours under conditions at temperature 37℃ to inactivate the enzyme and obtain enzymatic hydrolysis product 2. The mass ratio of the meat processing scraps, water and compound enzyme is 1:6:0.1. The compound enzyme is trypsin, papain and neutral protease with a mass ratio of 3.3:2.3:1.5.

[0047] (2) Inoculate Candida utilis and Pseudomonas aeruginosa into enzymatic hydrolysate 2, and ferment under aerobic conditions at pH 6 and 35℃ for 40 h. Filter to obtain fermentation filtrate; wherein the inoculation amount of Candida utilis is 3 wt%, and the viable cell count is 5 × 10⁻⁶. 8 CFU / ml; the inoculum amount of *Pseudomonas aeruginosa* was 3 wt%, and the viable count was 5 × 10⁻⁶. 9 CFU / mL;

[0048] (3) Based on the mass of waste protein raw materials, 0.12% of plant growth regulator, 12% urea, 7% potassium dihydrogen phosphate, 4% potassium sulfate, 0.7% ferrous sulfate and 0.4% zinc sulfate are added to the fermentation filtrate to prepare the amino acid-containing water-soluble fertilizer.

[0049] The plant growth regulator is chlorogenic acid, calcium cyclohexane, and methyl jasmonate in a mass ratio of 0.9:5:2.

[0050] Example 4

[0051] A method for preparing an amino acid-containing water-soluble fertilizer includes the following steps:

[0052] (1) Meat processing scraps are crushed, and then bean product processing waste residue and water are mixed to obtain a reaction substrate; the raw materials of the compound enzyme are added to the reaction substrate in steps for reaction. First, acidic protease is added to the reaction substrate, and enzymatic hydrolysis is carried out for 4 hours under aerobic conditions at pH 3 and temperature 45℃ to inactivate the enzyme and obtain enzymatic hydrolysis product 1; then the pH of enzymatic hydrolysis product 1 is adjusted to 7 with an alkali agent, and then neutral protease is added. Enzymatic hydrolysis is carried out for 5 hours under aerobic conditions at temperature 45℃ to inactivate the enzyme and obtain enzymatic hydrolysis product 2; wherein, the mass ratio of bean product processing waste residue, water and compound enzyme is 1:5:0.05; the compound enzyme is a mixture of neutral protease and acidic protease with a mass ratio of 2:1.

[0053] (2) Inoculate Candida utilis and Pseudomonas aeruginosa into enzymatic hydrolysate 2, and ferment under aerobic conditions at pH 5.5 and 30℃ for 35 h. Filter to obtain fermentation filtrate; wherein the inoculation amount of Candida utilis is 2 wt%, and the viable cell count is 2 × 10⁻⁶. 8 CFU / ml; the inoculum amount of *Pseudomonas aeruginosa* was 1.5 wt%, and the viable count was 4 × 10⁻⁶. 9 CFU / mL;

[0054] (3) Based on the mass of waste protein raw materials, 0.05% of plant growth regulator, 8% urea, 3% potassium dihydrogen phosphate, 2% potassium sulfate, 0.3% ferrous sulfate and 0.2% zinc sulfate are added to the fermentation filtrate to prepare the amino acid-containing water-soluble fertilizer.

[0055] The plant growth regulator is an amino oligosaccharide, phenylpeptide amino acid, and methyl jasmonate in a mass ratio of 1:4:1.5.

[0056] Comparative Example 1 (only protease digestion was performed)

[0057] A method for preparing an amino acid-containing water-soluble fertilizer includes the following steps:

[0058] (1) The meat processing scraps are crushed, and the meat processing scraps and water are mixed to obtain the reaction substrate. Papain and neutral protease are added to the reaction substrate, and the mixture is enzymatically hydrolyzed for 3.5 h under aerobic conditions at pH 7 and temperature 50℃ to inactivate the enzyme and obtain enzymatic hydrolysis product 1. The mixture is filtered and the enzymatic hydrolysis filtrate is collected. The pH of enzymatic hydrolysis product 1 is adjusted to 8.1 with an alkali agent, and then trypsin is added. The mixture is enzymatically hydrolyzed for 3 h under conditions at temperature 37℃ to inactivate the enzyme and obtain enzymatic hydrolysis product 2. The mass ratio of the meat processing scraps, water and compound enzyme is 1:5:0.05. The compound enzyme is trypsin, papain and neutral protease in a mass ratio of 3:2:1.

[0059] (2) Based on the mass of waste protein raw materials, 0.8% of plant growth regulator, 10% urea, 5% potassium dihydrogen phosphate, 3% potassium sulfate, 0.5% ferrous sulfate and 0.3% zinc sulfate are added to the enzymatic hydrolysis filtrate to prepare the amino acid-containing water-soluble fertilizer.

[0060] The plant growth regulator is chlorogenic acid, calcium cyclohexane, and methyl jasmonate in a mass ratio of 0.7:4:1.8.

[0061] Comparative Example 2 (Fermentation of microbial culture only)

[0062] A method for preparing an amino acid-containing water-soluble fertilizer includes the following steps:

[0063] (1) Crush meat processing scraps, mix the meat processing scraps with water to obtain a reaction substrate, inoculate Candida utilis and Pseudomonas aeruginosa into the reaction substrate, and ferment under aerobic conditions at pH 5.5 and 30℃ for 30-40 hours. Filter to obtain fermentation filtrate; wherein, the inoculation amount of Candida utilis is 2wt%, and the viable count is 3×10⁻⁶. 8 CFU / ml; the inoculum amount of *Pseudomonas aeruginosa* was 2 wt%, and the viable count was 4 × 10⁻⁶. 9 CFU / mL;

[0064] (2) Based on the mass of waste protein raw materials, 0.8% of plant growth regulator, 10% urea, 5% potassium dihydrogen phosphate, 3% potassium sulfate, 0.5% ferrous sulfate and 0.3% zinc sulfate are added to the fermentation filtrate to prepare the amino acid-containing water-soluble fertilizer.

[0065] The plant growth regulator is chlorogenic acid, calcium cyclohexane, and methyl jasmonate in a mass ratio of 0.7:4:1.8.

[0066] Comparative Example 3

[0067] The difference from Example 1 is that Comparative Example 3 replaces Candida utilis with Saccharomyces cerevisiae, while the other process parameters are the same as in Example 1.

[0068] Comparative Example 4

[0069] The difference from Example 1 is that Comparative Example 4 replaces Pseudomonas aeruginosa with Bacillus subtilis, while the other process parameters are the same as in Example 1.

[0070] Comparative Example 5 (using only Pseudomonas aeruginosa)

[0071] The difference from Example 1 is that Comparative Example 5 uses only *Pseudomonas aeruginosa* for fermentation. Specifically, *Pseudomonas aeruginosa* is inoculated into the enzymatic hydrolysis product 2, and fermented under aerobic conditions at pH 5.5 and 30°C for 30-40 hours. The mixture is then filtered to obtain the fermentation filtrate. The inoculation amount of *Pseudomonas aeruginosa* is 4 wt%, and the viable cell count is 4 × 10⁻⁶. 9 CFU / mL, with other process parameters the same as in Example 1.

[0072] Comparative Example 6 (using only Candida utilis)

[0073] The difference from Example 1 is that Comparative Example 6 only used *Candida utilis*. Specifically, *Candida utilis* was inoculated into enzymatic hydrolysate 2, and fermented under aerobic conditions at pH 5.5 and 30°C for 30-40 hours. The mixture was then filtered to obtain the fermentation filtrate. The inoculation amount of *Candida utilis* was 4 wt%, and the viable cell count was 3 × 10⁻⁶. 8 CFU / ml, with other process parameters the same as in Example 1.

[0074] Comparative Example 7 (adjusting the component ratio in the complex enzyme)

[0075] The difference from Example 1 is that the component ratio in the complex enzyme in Comparative Example 7 is adjusted. Specifically, the complex enzyme is trypsin, papain and neutral protease in a mass ratio of 1:1:1, and the other process parameters are the same as in Example 1.

[0076] Comparative Example 8 (reducing the dosage of plant growth regulators)

[0077] The difference from Example 1 is that the amount of plant growth regulator added in Comparative Example 8 was adjusted. Specifically, based on the mass of waste protein raw materials, 0.02% of plant growth regulator, 10% urea, 5% potassium dihydrogen phosphate, 3% potassium sulfate, 0.5% ferrous sulfate, and 0.3% zinc sulfate were added to the fermentation filtrate to obtain the amino acid-containing water-soluble fertilizer. The remaining process parameters were the same as in Example 1.

[0078] Comparative Example 9 (Increasing the dosage of plant growth regulators)

[0079] The difference from Example 1 is that the amount of plant growth regulator added in Comparative Example 9 was adjusted. Specifically, based on the mass of waste protein raw materials, 0.2% of plant growth regulator, 10% urea, 5% potassium dihydrogen phosphate, 3% potassium sulfate, 0.5% ferrous sulfate, and 0.3% zinc sulfate were added to the fermentation filtrate to obtain the amino acid-containing water-soluble fertilizer. The remaining process parameters were the same as in Example 1.

[0080] Comparative Example 10 (adjusting the raw material ratio of plant growth regulators)

[0081] The difference from Example 1 is that the raw material ratio of the plant growth regulator in Comparative Example 10 is adjusted. Specifically, the plant growth regulator is chlorogenic acid, calcium cyclohexane, and methyl jasmonate in a mass ratio of 2:3:1, and the other process parameters are the same as in Example 1.

[0082] Experimental Example 1

[0083] The free amino acid content in the fermentation filtrate or enzymatic hydrolysis filtrate was determined according to NY / T 1975-2010 "Determination of Free Amino Acid Content in Water-Soluble Fertilizers" in Examples 1-4 and Comparative Examples 1-7. The experimental results are shown in Table 1.

[0084] Table 1

[0085] Group Free amino acid content (g / L) Example 1 28.7 Example 2 26.1 Example 3 26.6 Example 4 24.3 Comparative Example 1 10.6 Comparative Example 2 12.2 Comparative Example 3 23.5 Comparative Example 4 22.3 Comparative Example 5 20.4 Comparative Example 6 18.7 Comparative Example 7 22.9

[0086] Experimental results show that the fermentation filtrate of this invention is prepared by a combination of enzymatic hydrolysis and microbial fermentation, which can increase the content of free amino acids in the fermentation filtrate.

[0087] Compared to Example 1, Comparative Examples 1-2 only used compound enzyme hydrolysis and microbial fermentation, resulting in a decrease in the free amino acid content in the fermentation filtrate. In this invention, a compound enzyme is first used to hydrolyze the reaction substrate. The protease in the compound enzyme can break down animal and plant proteins into small peptides and amino acids. Then, *Candida utilis* and *Pseudomonas aeruginosa* are added for fermentation. *Candida utilis* and *Pseudomonas aeruginosa* further break down the proteins and peptides in the reaction substrate into free amino acids by secreting alkaline protease, aminopeptidase, and extracellular enzymes. Simultaneously, *Candida utilis* and *Pseudomonas aeruginosa* can produce various amino acids during fermentation. Therefore, there is a synergistic effect between compound enzyme hydrolysis and microbial fermentation, which can increase the free amino acid content in the fermentation filtrate.

[0088] Compared to Example 1, in Comparative Examples 3-4, *Candida utilis* was replaced with *Saccharomyces cerevisiae* and *Pseudomonas aeruginosa* was replaced with *Bacillus subtilis*, respectively. Because *Saccharomyces cerevisiae* and *Bacillus subtilis* have different secretion mechanisms and reaction mechanisms than the strains selected in this invention, the free amino acid content in the fermentation filtrate decreased. In Comparative Examples 5-6, only a single strain was used for fermentation, resulting in a decrease in the free amino acid content in the fermentation filtrate. In this invention, both *Candida utilis* and *Pseudomonas aeruginosa* are used to ferment the enzymatic hydrolysate. The two fermentation strains have a synergistic effect, thus increasing the free amino acid content in the fermentation filtrate.

[0089] Compared to Example 1, Comparative Example 7, by altering the ratio of different proteases in the complex enzyme, resulted in a decrease in the free amino acid content of the fermentation filtrate. The rational combination of different proteases in this invention enhances their synergistic effect, enabling the complex enzyme to achieve optimal hydrolysis of the reaction substrate, thereby increasing the free amino acid content in the fermentation filtrate.

[0090] Experimental Example 2

[0091] In 2023, a field trial was conducted in Xintang Town, Zengcheng District, Guangzhou City, Guangdong Province. The amino acid-containing water-soluble fertilizers prepared in Example 1, Comparative Examples 3-4, and 8-10 were used for the experiment and were designated as experimental groups 1-6. Each experimental group used 10 four-year-old guava trees of the "Pearl" variety, with a spacing of 3*4m between the trees.

[0092] Fertilizer management: Dilute the amino acid-containing water-soluble fertilizer 800 times and apply it by root irrigation.

[0093] During the germination stage: apply 20g of fertilizer per plant (based on the weight of water-soluble fertilizer containing amino acids), once every 15 days;

[0094] From flowering to young fruit stage: apply 25g of fertilizer per plant (based on the weight of water-soluble fertilizer containing amino acids), once every 15 days;

[0095] During the fruit expansion period: apply 25g of fertilizer per plant (based on the weight of water-soluble fertilizer containing amino acids) every 10 days.

[0096] The yield per mu after the first fruit ripening was calculated, and 5 fruits were randomly selected from each guava tree to test the soluble sugar content (anthrone method) and VC content (2,6-dichlorophenolindophenol titration method). The average values ​​of soluble sugar content and VC content were calculated. The experimental results are shown in Table 2.

[0097] Soil samples were randomly taken from three locations at the rootstock of guava trees after harvesting. The activity of catalase was detected by KMnO4 titration and the activity of acid phosphatase was detected by disodium phenyl phosphate colorimetric method. The average values ​​of catalase activity and acid phosphatase activity were calculated. The experimental results are shown in Table 2.

[0098] Table 2

[0099] Group Yield (kg / mu) Soluble sugar content (g / 100g) Vitamin C content (mg / 100g) Catalase mL / (gh) Acid phosphatase mg / (kg·h) Example 1 3627 16.02 249.8 4.2 23.8 Comparative Example 3 3549 15.54 235.4 3.1 21.6 Comparative Example 4 3563 15.83 243.1 3.4 20.4 Comparative Example 8 3415 13.79 212.4 3.8 23.1 Comparative Example 9 3534 15.72 226.3 3.9 22.9 Comparative Example 10 3518 15.27 221.7 3.7 22.5

[0100] Experimental results show that the amino acid-containing water-soluble fertilizer of this invention can increase guava yield and vitamin C content in guava pulp, while also producing guava with higher sweetness. Detection of catalase and acid phosphatase activities in the soil indicates that the amino acid-containing water-soluble fertilizer prepared using this invention has the effect of improving soil physicochemical properties.

[0101] Compared to Example 1, in Comparative Examples 3-4, replacing *Candida utilis* with *Saccharomyces cerevisiae* and *Pseudomonas aeruginosa* with *Bacillus subtilis*, respectively, resulted in a decrease in the effectiveness of the amino acid-containing water-soluble fertilizer for guava cultivation. Detection of catalase and acid phosphatase activities in the soil indicated that the water-soluble fertilizer obtained by using *Candida utilis* and *Pseudomonas aeruginosa* as fermentation strains in this invention contains more effective components for improving soil physical properties, which is beneficial for increasing the guava tree yield in the following year.

[0102] Compared to Example 1, the proportion of plant growth regulators in water-soluble fertilizers was adjusted in Comparative Examples 8-9, resulting in a decrease in the effectiveness of amino acid-containing water-soluble fertilizers for guava cultivation. In this invention, by using appropriate amounts of plant growth regulators in synergy with other nutrients, nutrient absorption and metabolism in plants are further optimized, thereby improving the overall growth efficiency of crops.

[0103] Compared to Example 1, the adjustment of the raw material ratio in the plant growth regulator in Comparative Example 10 resulted in a decrease in the effectiveness of the amino acid-containing water-soluble fertilizer on guava cultivation. The rational ratio of the components in the plant growth regulator of this invention can improve the effectiveness of the water-soluble fertilizer.

[0104] The above description is merely a preferred embodiment of the present invention and is not intended to limit this application. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an aqueous amino acid-containing fertilizer, characterized by, The amino acid-containing water-soluble fertilizer comprises the following steps: (1) crushing a waste protein raw material, then adding water and a compound enzyme, and mixing, enzymolysis, and enzyme inactivation to obtain an enzymolysis product; wherein the compound enzyme is trypsin, papain, and neutral protease in a mass ratio of 2.5-3.3:1.6-2.3:0.5-1.5, or neutral protease and acid protease in a mass ratio of 1.5-2.5:1; (2) inoculating Candida utilis and Pseudomonas yamanensis into the enzymatic product for fermentation, filtering, and preparing a fermentation filtrate; wherein the inoculation amount of the Candida utilis is 1-3 wt%, and the viable bacterial count is (1-5) x 10 8 CFU / ml; the inoculation amount of the Pseudomonas yamanensis is 1-3 wt%, and the viable bacterial count is (3-5) x 10 9 CFU / mL; (3) adding a plant growth regulator, urea, potassium dihydrogen phosphate, potassium sulfate, ferrous sulfate, and zinc sulfate into the fermentation filtrate to obtain the amino acid-containing water-soluble fertilizer; wherein, according to the mass of the waste protein raw material, the plant growth regulator is added in an amount of 0.05%-0.12%, the urea is added in an amount of 8%-12%, the potassium dihydrogen phosphate is added in an amount of 3%-7%, the potassium sulfate is added in an amount of 2%-4%, the ferrous sulfate is added in an amount of 0.3%-0.7%, and the zinc sulfate is added in an amount of 0.2%-0.4%; the plant growth regulator is chlorogenic acid, calcium tobramycin, and methyl jasmonate in a mass ratio of 0.4-0.9:3-5:1.5-2; the waste protein raw material is an animal protein.

2. The method for preparing amino acid-containing water-soluble fertilizer as described in claim 1, characterized in that, In step (1), the mass ratio of the waste protein raw material, water, and the compound enzyme is 1:4-6:0.01-0.

1.

3. The method for preparing amino acid-containing water-soluble fertilizer as described in claim 1, characterized in that, In step (1), the enzymolysis is carried out at pH 2-9 and 30-60℃ for 5-30h.

4. The method for preparing amino acid-containing water-soluble fertilizer as described in claim 1, characterized in that, In step (2), the fermentation is carried out at pH 5-6 and 25-35℃ under aerobic conditions for 30-40h.

5. An aqueous amino acid-containing fertilizer, characterized by, The amino acid-containing water-soluble fertilizer is prepared by the preparation method in any one of claims 1-4.