Compound amino acid liquid fertilizer and preparation process thereof

Abstract

The invention relates to the technical field of fertilizer preparation, in particular to a compound amino acid liquid fertilizer and a preparation process thereof. The preparation process comprises the following steps: preparing the amino acid composite collagen sponge; preparing a composite cross-linking solution; soaking the amino acid composite collagen sponge in the composite cross-linking solution; and preparing the compound amino acid liquid fertilizer. According to the invention, polyacrylic acid and gamma-polyglutamic acid are subjected to cross-linking copolymerization to form a composite cross-linking solution, a cross-linking three-dimensional network structure is constructed, the water-retaining property and the adsorption capacity of the composite cross-linking solution are improved through the synergistic cross-linking, and polyacrylic acid as a polyelectrolyte can prevent aspartic acid from crystallizing in water, so that the adsorption capacity of the composite cross-linking solution is improved. The aspartic acid can be uniformly dispersed in the liquid fertilizer, absorption of trace elements is promoted, coordinated supply of crop nutrients is achieved, and the situation of malnutrition of crops is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of fertilizer preparation, and in particular to a composite amino acid liquid fertilizer and a preparation process thereof. Background Art

[0002] As global climate change intensifies, the crop growth environment is becoming increasingly complex and changeable. Environmental pressures such as drought, floods, salinity, pests and diseases pose severe challenges to crop growth. These adverse factors not only affect the normal growth cycle of crops, but may also lead to a sharp drop in yields. Although traditional inorganic fertilizers can quickly increase crop yields in the short term, their low utilization rate, easy loss, and easy pollution of soil and water sources are becoming increasingly prominent. The utilization rate of phosphorus and potassium fertilizers in crops in the season is only about 20%, and the utilization rate of nitrogen fertilizers in crops in the season is only about 35%. This not only causes waste of resources and economic losses, but also aggravates environmental pollution problems. In addition, long-term reliance on inorganic fertilizers can easily lead to soil structure damage and reduced fertility.

[0003] Soil moisture is one of the key factors affecting crop growth and development. Appropriate soil moisture content can promote crop root growth and nutrient absorption, improve crop resistance and yield. Compared with traditional inorganic fertilizers, amino acid fertilizers improve soil moisture conditions through a variety of mechanisms, thereby promoting crop growth and increasing yields, thereby solving some of the environmental pollution problems that traditional inorganic fertilizers may cause. However, solid crystals are prone to appear in the amino acid fertilizer solution at low or normal temperatures. These crystals may affect the uniformity and stability of the fertilizer, and thus affect the absorption effect of the crop. This is because the solubility and chelating power of trace elements and other ingredients in amino acid fertilizers are limited. If too many trace elements are added to the formula, it will lead to a large amount of crystallization at low or normal temperatures, thereby affecting the ability of amino acid fertilizers to regulate soil moisture content.

[0004] Therefore, the present invention provides a composite amino acid liquid fertilizer and a preparation process thereof to solve the problems existing in the above-mentioned prior art. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention aims to provide a composite amino acid liquid fertilizer and a preparation process thereof.

[0006] A preparation process of a composite amino acid liquid fertilizer comprises the following steps: S1: Preparation of amino acid composite collagen sponge S1.1: Dissolve collagen powder with acetic acid solution to prepare a solution with a collagen concentration of 2-2.2 mg / mL, centrifuge the collagen solution at a speed of 5000-5200 r / min and degas for 10-15 min at a low temperature of 0-4°C, then place it in an ice water bath, and simultaneously place the probe of a cell disruptor in the collagen solution for ultrasonic treatment for 2-5 min to obtain a collagen base solution; S1.2: Mix 1-2 parts by mass of collagen base liquid, 3-6 parts by mass of 0.2 mol / L NaCl solution and 0.4-0.8 parts by mass of complex amino acids and stir evenly, place in a 20-25°C water bath and let stand for 15-25 minutes to obtain a self-assembly liquid, dialyze the self-assembly liquid against an acetic acid solution for 12-13 hours, then dialyze against distilled water for 12-13 hours, and freeze-dry to obtain an amino acid composite collagen sponge.

[0007] Furthermore, in step S1.2, the composite amino acid is prepared by mixing glutamic acid, tyrosine, histidine and water in a mass ratio of 1: (2-3): (0.2-0.5): (10-25).

[0008] Furthermore, in step S1, the concentration of the acetic acid solution is 0.1 mol / L.

[0009] S2: Preparation of composite cross-linking solution S2.1: Add 10 parts by mass of 0.1M citric acid / sodium citrate buffer to the reaction bottle, then add 0.1-0.3 parts by mass of polyacrylic acid and 0.2-0.4 parts by mass of γ-polyglutamic acid, stir until dissolved and mixed uniformly, and adjust the pH value to 6-6.5 with 0.1M sodium bicarbonate buffer; S2.2: Add 0.1-0.2 parts by mass of carbodiimide hydrochloride and 0.15-0.25 parts by mass of N-hydroxysuccinimide to the reaction bottle, stir with a magnetic stirrer for 10-15 minutes, then let stand for 15-30 minutes, and then adjust the solution pH to 7-7.5 with 0.1M PBS buffer to obtain a composite cross-linking solution.

[0010] Furthermore, the molecular weight of the polyacrylic acid in step S2.1 is 300-400 kDa.

[0011] Furthermore, in step S2.1, the citric acid / sodium citrate buffer is prepared by mixing citric acid and sodium citrate in a mass ratio of 1:(1-1.5).

[0012] S3: Soak the amino acid composite collagen sponge in the composite cross-linking solution The amino acid composite collagen sponge is crushed and passed through a 150-mesh sieve to obtain amino acid composite collagen sponge particles, which are then added to the composite cross-linking solution to react for 30-35 minutes. The solid-liquid ratio of the amino acid composite collagen sponge particles to the composite cross-linking solution is 1g: (10-20)mL. The amino acid composite collagen sponge particles are then taken out, rinsed with deionized water for 5-6 times, and allowed to stand for 12-24 hours to dry, to obtain a three-dimensional amino acid collagen sponge / polyelectrolyte complex.

[0013] S4: Preparation of compound amino acid liquid fertilizer 15-20 parts by weight of three-dimensional amino acid collagen sponge / polyelectrolyte complex, 15-25 parts by weight of urea, 2-3 parts by weight of humic acid, 2-6 parts by weight of aspartic acid and 20-40 parts by weight of pure water are uniformly mixed to prepare a composite amino acid liquid fertilizer.

[0014] Furthermore, the preparation method of collagen powder is specifically as follows: take a piece of pig skin, cut it into small pieces, soak it in sodium carbonate solution and NaCl solution, the solid-liquid ratio is 1g: (10-15) mL, use distilled water 3 times after the soaking, grind it into flocs and freeze it at 0-4°C to obtain pig skin pieces, add 0.9-1.5% papain solution by mass to the pig skin pieces, stir evenly and then ultrasonically treat it for 5-10 minutes, place it in a constant temperature oscillator at 37-39°C for reaction for 3-4 hours, centrifuge it at 8000-8100r / min for 20-25 minutes after the end, retain the supernatant, add an equal volume of NaCl solution with a concentration of 0.9mol / L to the supernatant, salt out at 5-10°C for 12-14 hours, centrifuge it again at 8000-8100r / min for 20-25 minutes after the salting out, obtain a precipitate, dialyze the precipitate, and dry it to obtain collagen powder.

[0015] A composite amino acid liquid fertilizer is prepared by the above-mentioned composite amino acid liquid fertilizer preparation process.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: 1. The present invention crosslinks and copolymerizes polyacrylic acid and γ-polyglutamic acid to form a composite crosslinking solution. Polyacrylic acid contains a large number of carboxyl groups. γ-polyglutamic acid is a polyamino acid formed by polymerizing glutamic acid monomers through γ-amide bonds, and its molecular chain contains a large number of carboxyl groups and amino groups. When polyacrylic acid and γ-polyglutamic acid participate in the crosslinking reaction together, the carboxyl groups of both can be activated by NHS, and then form covalent bonds to construct a crosslinked three-dimensional network structure. This synergistic crosslinking not only enhances the water retention and adsorption capacity of the material, but also, polyacrylic acid, as a polyelectrolyte, contains a large number of dissociable groups, namely carboxyl groups, which form charged polymer chains after dissociation in the solution. These charged chain segments can be combined with the charged groups on the aspartic acid molecules through electrostatic interaction, thereby interfering with the aggregation and crystallization process of the aspartic acid molecules, preventing the crystallization of aspartic acid in water, so that the aspartic acid can be evenly dispersed in the liquid fertilizer. While improving the water retention capacity and moisture content of the soil, the aspartic acid is evenly dispersed in the soil with the solvent water, promoting the absorption of trace elements, achieving the coordinated supply of crop nutrients, and avoiding the malnutrition of crops.

[0017] 2. The present invention self-assembles composite amino acids and collagen sponges to construct amino acid composite collagen sponges. After the collagen sponges are loaded with amino acids, the stability of the amino acids can be improved, the amino acids can be prevented from crystallizing, and the loaded amino acid molecules can be slowly released. The amino acid molecules are degraded over time after release, and their degradation products can release multivalent cations. These cations can form bridge bonds between soil particles and organic matter, promote the agglomeration of soil particles, improve the physical and chemical properties of the soil, promote the formation of soil aggregates, thereby increasing the air permeability and water retention of the soil, and reducing soil compaction. In addition, the collagen sponge can also be combined with a three-dimensional network structure formed with polyacrylic acid and γ-polyglutamic acid as raw materials to form an interpenetrating polymer network. The interpenetrating polymer network is a mixed system composed of two or more cross-linked and mutually penetrating polymer networks. In this structure, the networks of collagen sponges and polyacrylic acid are intertwined, but there is no chemical bonding between them, and the characteristics of each network can be retained, so that the polymer can not only improve the water retention capacity and moisture content of the soil, but also improve the stability of amino acids and make the amino acids evenly dispersed.

[0018] 3. The present invention buffers polyacrylic acid and γ-polyglutamic acid by citric acid / sodium citrate buffer. The citric acid buffer can maintain the pH value of the solution within a certain range, so that the pH value in the solution remains relatively stable, thereby adjusting the polymerization environment of polyacrylic acid, and thereby adjusting the cross-linking degree of the polymer network, further improving the performance of the composite. At the same time, the citric acid buffer is a non-toxic, biodegradable buffer. The material prepared by using the citric acid buffer to buffer polyacrylic acid has excellent environmental friendliness and will not cause pollution to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable those skilled in the relevant art to make and use the present disclosure.

[0020] Figure 1 The present invention is a flow chart of a process for preparing a composite amino acid liquid fertilizer used in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following is a detailed description of a composite amino acid liquid fertilizer and its preparation process provided by the present invention in conjunction with the accompanying drawings and specific embodiments. At the same time, it is explained here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and those skilled in the art may also adopt other alternatives to implement some known technologies; and the accompanying drawings are only for a more specific description of the embodiments, and are not intended to specifically limit the present invention.

[0022] Embodiment 1: A preparation process of a composite amino acid liquid fertilizer, such as Figure 1 As shown, the following steps are included: S1: Preparation of amino acid composite collagen sponge S1.1: Take a piece of pig skin, cut it into small pieces of 0.5cm*0.5cm, soak it in 5wt% sodium carbonate solution and 5wt% NaCl solution for 24h respectively, with a solid-liquid ratio of 1g:10mL, wash with distilled water 3 times after soaking, grind it into floccules and freeze it at 0℃ to obtain pig skin pieces, add 0.9% papain solution of the system mass to the pig skin pieces, stir evenly and ultrasonicate for 5min, place it in a constant temperature oscillator at 37℃ for reaction for 3h, centrifuge it at 8000r / min for 20min after reaction, retain the supernatant, add an equal volume of 0.9mol / L NaCl solution to the supernatant, salt out at 5℃ for 12h, centrifuge it again at 8000r / min for 20min after salt out to obtain a precipitate, dialyze the precipitate, and dry it to obtain collagen powder; Dissolve collagen powder with 0.1 mol / L acetic acid solution to prepare a solution with a collagen concentration of 2 mg / mL, centrifuge the collagen solution at a speed of 5000 r / min and degas for 10 min at a low temperature of 0°C, then place it in an ice water bath, and simultaneously place the probe of a cell disruptor in the collagen solution for ultrasonic treatment for 2 min to obtain a collagen base solution; S1.2: Mix 1 part by mass of collagen base liquid, 3 parts by mass of 0.2 mol / L NaCl solution and 0.4 parts by mass of complex amino acids and stir them evenly. The complex amino acids are prepared by mixing glutamic acid, tyrosine, histidine and water in a mass ratio of 1:2:0.2:10. Place it in a 20°C water bath and let it stand for 15 minutes to obtain a self-assembly liquid. The self-assembly liquid is dialyzed against a 0.1 mol / L acetic acid solution for 12 hours, and then dialyzed against distilled water for 12 hours. Freeze-drying is performed to obtain an amino acid composite collagen sponge.

[0023] S2: Preparation of composite cross-linking solution S2.1: Add 10 parts by mass of 0.1M citric acid / sodium citrate buffer to the reaction bottle, wherein the citric acid / sodium citrate buffer is prepared by mixing citric acid and sodium citrate in a mass ratio of 1:1, then add 0.1 parts by mass of polyacrylic acid and 0.2 parts by mass of γ-polyglutamic acid, wherein the molecular weight of polyacrylic acid is 300 kDa, stir until dissolved and mixed uniformly, and adjust the pH value to 6 with 0.1M sodium bicarbonate buffer; S2.2: Add 0.1 parts by mass of carbodiimide hydrochloride and 0.15 parts by mass of N-hydroxysuccinimide to the reaction bottle, stir with a magnetic stirrer for 10 minutes, then let stand for 15 minutes, and then adjust the solution pH to 7 with 0.1 M PBS buffer to obtain a composite cross-linking solution.

[0024] S3: Soak the amino acid composite collagen sponge in the composite cross-linking solution The amino acid composite collagen sponge was crushed and passed through a 150-mesh sieve to obtain amino acid composite collagen sponge particles, which were then added to the composite cross-linking solution to react for 30 minutes. The solid-liquid ratio of the amino acid composite collagen sponge particles and the composite cross-linking solution was 1 g:10 mL. The amino acid composite collagen sponge particles were then taken out, rinsed with deionized water 5 times, and allowed to stand for 12 hours to dry to obtain a three-dimensional amino acid collagen sponge / polyelectrolyte complex.

[0025] S4: Preparation of compound amino acid liquid fertilizer 15 parts by mass of three-dimensional amino acid collagen sponge / polyelectrolyte complex, 15 parts by mass of urea, 2 parts by mass of humic acid, 2 parts by mass of polyglutamic acid and 20 parts by mass of pure water were uniformly mixed to prepare a composite amino acid liquid fertilizer.

[0026] Embodiment 2: A preparation process of a composite amino acid liquid fertilizer, such as Figure 1 As shown, the following steps are included: S1: Preparation of amino acid composite collagen sponge S1.1: Take a piece of pig skin, cut it into small pieces of 0.5cm*0.5cm, soak it in 5wt% sodium carbonate solution and 5wt% NaCl solution for 24h respectively, with a solid-liquid ratio of 1g:15mL, wash with distilled water 3 times after soaking, grind it into floccules and freeze it at 0℃ to obtain pig skin pieces, add 1.5% papain solution of the system weight to the pig skin pieces, stir evenly and ultrasonicate it for 5min, place it in a constant temperature oscillator at 37℃ for reaction for 3h, centrifuge it at 8000r / min for 20min after reaction, retain the supernatant, add an equal volume of 0.9mol / L NaCl solution to the supernatant, salt out at 5℃ for 12h, centrifuge it again at 8000r / min for 20min after salt out to obtain a precipitate, dialyze the precipitate, and dry it to obtain collagen powder; Dissolve the collagen powder with 0.1 mol / L acetic acid solution to prepare a solution with a collagen concentration of 2.2 mg / mL, centrifuge the collagen solution at a speed of 5000 r / min and degas for 10 min at a low temperature of 0°C, then place it in an ice water bath, and simultaneously place the probe of a cell disruptor in the collagen solution for ultrasonic treatment for 2 min to obtain a collagen base solution; S1.2: Mix 2 parts by mass of collagen base liquid, 6 parts by mass of 0.2 mol / L NaCl solution and 0.8 parts by mass of complex amino acids and stir them evenly. The complex amino acids are prepared by mixing glutamic acid, tyrosine, histidine and water in a mass ratio of 1:3:0.5:25. Place it in a 20°C water bath and let it stand for 15 minutes to obtain a self-assembly liquid. The self-assembly liquid is dialyzed against a 0.1 mol / L acetic acid solution for 12 hours, then dialyzed against distilled water for 12 hours, and freeze-dried to obtain an amino acid composite collagen sponge.

[0027] S2: Preparation of composite cross-linking solution S2.1: Add 10 parts by mass of 0.1M citric acid / sodium citrate buffer to the reaction bottle, wherein the citric acid / sodium citrate buffer is prepared by mixing citric acid and sodium citrate in a mass ratio of 1:1.5, then add 0.3 parts by mass of polyacrylic acid and 0.4 parts by mass of γ-polyglutamic acid, wherein the molecular weight of polyacrylic acid is 300 kDa, stir until dissolved and mixed uniformly, and adjust the pH value to 6 with 0.1M sodium bicarbonate buffer; S2.2: Add 0.2 parts by mass of carbodiimide hydrochloride and 0.25 parts by mass of N-hydroxysuccinimide to the reaction bottle, stir with a magnetic stirrer for 10 minutes, then let stand for 15 minutes, and then adjust the solution pH to 7 with 0.1 M PBS buffer to obtain a composite cross-linking solution.

[0028] S3: Soak the amino acid composite collagen sponge in the composite cross-linking solution The amino acid composite collagen sponge was crushed and passed through a 150-mesh sieve to obtain amino acid composite collagen sponge particles, which were then added to the composite cross-linking solution to react for 30 minutes. The solid-liquid ratio of the amino acid composite collagen sponge particles and the composite cross-linking solution was 1 g:20 mL. The amino acid composite collagen sponge particles were then taken out, rinsed with deionized water 5 times, and allowed to stand for 12 hours to dry, to obtain a three-dimensional amino acid collagen sponge / polyelectrolyte complex.

[0029] S4: Preparation of compound amino acid liquid fertilizer 20 parts by mass of three-dimensional amino acid collagen sponge / polyelectrolyte complex, 25 parts by mass of urea, 3 parts by mass of humic acid, 6 parts by mass of polyglutamic acid and 40 parts by mass of pure water were uniformly mixed to prepare a composite amino acid liquid fertilizer.

[0030] Embodiment 3: A preparation process of a composite amino acid liquid fertilizer, such as Figure 1 As shown, the following steps are included: S1: Preparation of amino acid composite collagen sponge S1.1: Take a piece of pig skin, cut it into small pieces of 0.5cm*0.5cm, soak it in 5wt% sodium carbonate solution and 5wt% NaCl solution for 24h respectively, with a solid-liquid ratio of 1g:10mL, wash it with distilled water 3 times after soaking, grind it into floccules and freeze it at 0℃ to obtain pig skin pieces, add 0.9% papain solution of the system mass to the pig skin pieces, stir evenly and ultrasonically treat it for 10min, place it in a constant temperature oscillator at 37℃ for reaction for 4h, centrifuge it at 8100r / min for 25min after reaction, retain the supernatant, add an equal volume of 0.9mol / L NaCl solution to the supernatant, salt out at 10℃ for 14h, centrifuge it again at 8100r / min for 25min after salt out, obtain a precipitate, dialyze the precipitate, and dry it to obtain collagen powder; Dissolve the collagen powder with 0.1 mol / L acetic acid solution to prepare a solution with a collagen concentration of 2 mg / mL, centrifuge the collagen solution at a speed of 5200 r / min and degas for 15 minutes at a low temperature of 4°C, then place it in an ice water bath, and simultaneously place the probe of a cell disruptor in the collagen solution for ultrasonic treatment for 5 minutes to obtain a collagen base solution; S1.2: Mix 1 part by mass of collagen base liquid, 3 parts by mass of 0.2 mol / L NaCl solution and 0.4 parts by mass of complex amino acids and stir them evenly. The complex amino acids are prepared by mixing glutamic acid, tyrosine, histidine and water in a mass ratio of 1:2:0.2:10. Place it in a 25°C water bath and let it stand for 25 minutes to obtain a self-assembly liquid. The self-assembly liquid is dialyzed against a 0.1 mol / L acetic acid solution for 14 hours, then dialyzed against distilled water for 12 hours, and freeze-dried to obtain an amino acid composite collagen sponge.

[0031] S2: Preparation of composite cross-linking solution S2.1: Add 10 parts by mass of 0.1M citric acid / sodium citrate buffer to the reaction bottle, wherein the citric acid / sodium citrate buffer is prepared by mixing citric acid and sodium citrate in a mass ratio of 1:1, then add 0.1 parts by mass of polyacrylic acid and 0.2 parts by mass of γ-polyglutamic acid, wherein the molecular weight of polyacrylic acid is 300 kDa, stir until dissolved and mixed uniformly, and adjust the pH value to 6.5 with 0.1M sodium bicarbonate buffer; S2.2: Add 0.1 parts by mass of carbodiimide hydrochloride and 0.15 parts by mass of N-hydroxysuccinimide to the reaction bottle, stir with a magnetic stirrer for 15 minutes, then let stand for 30 minutes, and then adjust the pH value of the solution to 7.5 with 0.1 M PBS buffer to obtain a composite cross-linking solution.

[0032] S3: Soak the amino acid composite collagen sponge in the composite cross-linking solution The amino acid composite collagen sponge was crushed and passed through a 150-mesh sieve to obtain amino acid composite collagen sponge particles, which were then added to the composite cross-linking solution to react for 35 minutes. The solid-liquid ratio of the amino acid composite collagen sponge particles and the composite cross-linking solution was 1 g:10 mL. The amino acid composite collagen sponge particles were then taken out, rinsed with deionized water 6 times, and allowed to stand for 14 hours to dry, to obtain a three-dimensional amino acid collagen sponge / polyelectrolyte complex.

[0033] S4: Preparation of compound amino acid liquid fertilizer 15 parts by mass of three-dimensional amino acid collagen sponge / polyelectrolyte complex, 15 parts by mass of urea, 2 parts by mass of humic acid, 2 parts by mass of polyglutamic acid and 20 parts by mass of pure water were uniformly mixed to prepare a composite amino acid liquid fertilizer.

[0034] Comparative Example 1: Comparative Example 1 is a commercially available amino acid liquid fertilizer.

[0035] Comparative Example 2: Compared with Example 1, the difference of Comparative Example 2 is that step S1.1 is not performed, and no collagen base liquid is added in step S1.2, specifically "S1.2: Mix 3 parts by mass of 0.2 mol / L NaCl solution and 0.4 parts by mass of composite amino acids and stir them evenly, the composite amino acids are prepared by mixing glutamic acid, tyrosine, histidine and water in a mass ratio of 1:2:0.2:10, and stand in a 20°C water bath for 15 minutes to obtain a self-assembly liquid, and the self-assembly liquid is dialyzed against 0.1 mol / L acetic acid solution for 12 hours, and then dialyzed against distilled water for 12 hours, and freeze-dried to obtain a composite amino acid powder", and the composite amino acid powder is used instead of the amino acid composite collagen sponge, and the other steps remain unchanged, and the prepared composite amino acid liquid fertilizer is recorded as 2.

[0036] Comparative Example 3: Compared with Example 1, the difference of Comparative Example 3 is that no polyacrylic acid is added in step S2.1, specifically "S2.1: add 10 parts by mass of 0.1M citric acid / sodium citrate buffer to the reaction bottle, the citric acid / sodium citrate buffer is specifically prepared by mixing citric acid and sodium citrate in a mass ratio of 1:1, and then add 0.2 parts by mass of γ-polyglutamic acid, stir until dissolved and mixed evenly, and adjust the pH value to 6 with 0.1M sodium bicarbonate buffer", and the other steps remain unchanged, and the prepared composite amino acid liquid fertilizer is recorded as 3.

[0037] Comparative Example 4: Compared with Example 1, the difference of Comparative Example 4 is that γ-polyglutamic acid is not added in step S2.1, specifically "S2.1: add 10 parts by mass of 0.1M citric acid / sodium citrate buffer to the reaction bottle, the citric acid / sodium citrate buffer is specifically prepared by mixing citric acid and sodium citrate in a mass ratio of 1:1, and then add 0.1 parts by mass of polyacrylic acid, the molecular weight of polyacrylic acid is 300kDa, stir until dissolved and mixed evenly, and adjust the pH value to 6 with 0.1M sodium bicarbonate buffer", and the other steps remain unchanged, and the prepared composite amino acid liquid fertilizer is recorded as 4.

[0038] Comparative Example 5: Compared with Example 1, the difference of Comparative Example 5 is that step S3 is not performed, and collagen sponge is used instead of the three-dimensional amino acid collagen sponge / polyelectrolyte complex in step S4, specifically "S4: preparing composite amino acid liquid fertilizer: 15 parts by mass of collagen sponge, 15 parts by mass of urea, 2 parts by mass of humic acid, 2 parts by mass of polyglutamic acid and 20 parts by mass of pure water are mixed evenly to form a composite amino acid liquid fertilizer", and the other steps remain unchanged, and the prepared composite amino acid liquid fertilizer is recorded as 5.

[0039] 24 healthy sweet potato seedlings of the same growth were prepared and divided into 8 groups of 3 plants each. The compound amino acid liquid fertilizers of Examples 1-3 and Comparative Examples 1-5 were applied respectively. The average yield and single potato weight of the sweet potatoes in each group were counted, wherein the average yield was the total yield of sweet potatoes in each group / 3 (plants), and the single potato weight was the total mass of sweet potatoes in each group / the total number of sweet potatoes in each group. The results are shown in Table 1.

[0040] Table 1

[0041] 500 g of each of Examples 1-3 and Comparative Examples 1-5 were placed in a 4°C environment to simulate a refrigerated environment for 14 days, and the crystallization of the Examples and Comparative Examples was observed, as shown in Table 2.

[0042] Table 2:

[0043] As can be seen from Table 1, the outputs of Examples 1, 2, and 3 are 862.5g, 932.8g, and 925.9g, respectively, and the single potato weights of Examples 1, 2, and 3 are 172.5g, 174.9g, and 173.6g, respectively. From the perspective of output, the output of the embodiments is generally higher than that of the comparative example, and the output of Example 2 is the highest, reaching 932.8g, while the output of Comparative Example 1 is 705.6g, and the single potato weight is 151.2g. The soil moisture content during the sweet potato planting process can indeed directly affect the yield, and the soil moisture content not only affects the growth of sweet potatoes, but is also closely related to soil fertility. Suitable moisture content contributes to the activity of soil microorganisms, promotes the decomposition of organic matter and the release of nutrients, thereby improving soil fertility. Therefore, it can be intuitively seen from the output and the single potato weight that the composite amino acid liquid fertilizer of the present invention has a better effect of regulating soil moisture and promoting the growth of sweet potato yield than commercially available products.

[0044] The yields of Comparative Examples 2-5 were 626.3 g, 622.3 g, 660.3 g and 646.3 g, respectively, and the single potato weights were 134.8 g, 143.6 g, 141.5 g and 138.5 g, respectively. It can be seen that the various components of the present invention have a synergistic effect, and their combined use can regulate soil moisture and promote the increase of sweet potato yield.

[0045] As can be seen from Table 2, the initial crystallization time of Examples 1-3 is 6 days, but the crystallization amount is 72g, 69g and 71g respectively. This shows that under the same initial crystallization time, there is a certain fluctuation in the crystallization amount, but the overall difference is not large. The initial crystallization time of Comparative Example 1 is 5 days and the crystallization amount is 78g. This shows that the initial crystallization time is advanced, the total crystallization time increases, and the crystallization amount increases slightly. At the same time, it can also be seen that the crystallization amount of the present invention is lower than that of commercially available products, and has a better ability to prevent crystallization.

[0046] The initial crystallization time of Comparative Examples 2-4 is 2-3 days, and the crystallization amount is 92g, 86g, 84g and 93g, respectively. It can also be proved that the initial crystallization time is advanced and the total crystallization time is increased, which will lead to an increase in the crystallization amount. Therefore, it can be seen that the various components of the present invention have the ability to reduce the crystallization of amino acids, which can reduce the crystallization amount of amino acid fertilizers during long-term storage, and better preserve and apply.

[0047] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A preparation process of a composite amino acid liquid fertilizer, characterized in that: The steps include: S1: Preparation of amino acid composite collagen sponge dissolving collagen powder with acetic acid solution to prepare collagen base solution, mixing the collagen base solution, NaCl solution and composite amino acids and stirring evenly to obtain self-assembly solution, dialyzing the self-assembly solution, and freeze-drying to obtain amino acid composite collagen sponge; S2: Preparation of composite cross-linking solution Adding polyacrylic acid and γ-polyglutamic acid to a citric acid / sodium citrate buffer, and then adding carbodiimide hydrochloride and N-hydroxysuccinimide to obtain a composite cross-linking solution; S3: Soak the amino acid composite collagen sponge in the composite cross-linking solution The amino acid composite collagen sponge is crushed and sieved to obtain amino acid composite collagen sponge particles, which are then added to a composite cross-linking solution for reaction for 30-35 minutes, and then the amino acid composite collagen sponge particles are taken out, rinsed with deionized water, and allowed to stand and dry to obtain a three-dimensional amino acid collagen sponge / polyelectrolyte complex; S4: Preparation of compound amino acid liquid fertilizer 15-20 parts by weight of three-dimensional amino acid collagen sponge / polyelectrolyte complex, 15-25 parts by weight of urea, 2-3 parts by weight of humic acid, 2-6 parts by weight of aspartic acid and 20-40 parts by weight of pure water are uniformly mixed to prepare a composite amino acid liquid fertilizer.

2. The preparation process of a composite amino acid liquid fertilizer according to claim 1, characterized in that: Step S1: preparing amino acid composite collagen sponge, comprising the following steps: S1.1: Dissolve collagen powder with acetic acid solution to prepare a solution with a collagen concentration of 2-2.2 mg / mL, centrifuge the collagen solution at a speed of 5000-5200 r / min and degas for 10-15 min at a low temperature of 0-4°C, then place it in an ice water bath, and simultaneously place the probe of a cell disruptor in the collagen solution for ultrasonic treatment for 2-5 min to obtain a collagen base solution; S1.2: Mix 1-2 parts by mass of collagen base liquid, 3-6 parts by mass of 0.2 mol / L NaCl solution and 0.4-0.8 parts by mass of complex amino acids and stir evenly, place in a 20-25°C water bath and let stand for 15-25 minutes to obtain a self-assembly liquid, dialyze the self-assembly liquid against an acetic acid solution for 12-13 hours, then dialyze against distilled water for 12-13 hours, and freeze-dry to obtain an amino acid composite collagen sponge.

3. The preparation process of a composite amino acid liquid fertilizer according to claim 2, characterized in that: Step S2 prepares a composite cross-linking solution, comprising the following steps: S2.1: Add 10 parts by mass of 0.1M citric acid / sodium citrate buffer to the reaction bottle, then add 0.1-0.3 parts by mass of polyacrylic acid and 0.2-0.4 parts by mass of γ-polyglutamic acid, stir until dissolved and mixed uniformly, and adjust the pH value to 6-6.5 with 0.1M sodium bicarbonate buffer; S2.2: Add 0.1-0.2 parts by mass of carbodiimide hydrochloride and 0.15-0.25 parts by mass of N-hydroxysuccinimide to the reaction bottle, stir with a magnetic stirrer for 10-15 minutes, then let stand for 15-30 minutes, and then adjust the solution pH to 7-7.5 with 0.1M PBS buffer to obtain a composite cross-linking solution.

4. The preparation process of a composite amino acid liquid fertilizer according to claim 3, characterized in that: The preparation method of collagen powder is specifically as follows: take a piece of pig skin, cut it into small pieces, soak it in sodium carbonate solution and NaCl solution, the solid-liquid ratio is 1g: (10-15) mL, use distilled water 3 times after soaking, stir it into flocs and freeze it at 0-4°C to obtain pig skin pieces, add 0.9-1.5% papain solution of the system mass to the pig skin pieces, stir it evenly and then ultrasonically treat it for 5-10 minutes, place it in a constant temperature oscillator at 37-39°C for reaction for 3-4 hours, centrifuge it at 8000-8100r / min for 20-25 minutes after the end, retain the supernatant, add an equal volume of NaCl solution with a concentration of 0.9mol / L to the supernatant, salt out at 5-10°C for 12-14 hours, centrifuge it again at 8000-8100r / min for 20-25 minutes after the salting out, obtain a precipitate, dialyze the precipitate, and dry it to obtain collagen powder.

5. The preparation process of a composite amino acid liquid fertilizer according to claim 2, characterized in that: In step S1.2, the composite amino acid is prepared by mixing glutamic acid, tyrosine, histidine and water in a mass ratio of 1:(2-3):(0.2-0.5):(10-25).

6. The preparation process of a composite amino acid liquid fertilizer according to claim 1, characterized in that: The concentration of the acetic acid solution in step S1 is 0.1 mol / L.

7. The preparation process of a composite amino acid liquid fertilizer according to claim 3, characterized in that: The molecular weight of the polyacrylic acid in step S2.1 is 300-400 kDa.

8. The preparation process of a composite amino acid liquid fertilizer according to claim 3, characterized in that: The citric acid / sodium citrate buffer in step S2.1 is prepared by mixing citric acid and sodium citrate in a mass ratio of 1:(1-1.5).

9. A composite amino acid liquid fertilizer, characterized in that: The liquid fertilizer is prepared by the preparation process of the composite amino acid liquid fertilizer according to any one of claims 1 to 8.

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