Amino acid water-soluble fertilizer, preparation method and application thereof

Abstract

The present application relates to the technical field of agricultural fertilizer, and discloses an amino acid water-soluble fertilizer, a preparation method thereof and application, which comprises: the fertilizer is made of protein hydrolysis amino acid stock solution of sick and dead livestock and poultry, crystal type regulation and dynamic protection agent, alkaline neutralizing agent and secondary hydrolysis composite enzyme. The present application changes the primary crystal nucleus morphology of inorganic salt when the stock solution is neutralized by adding the crystal type regulation and dynamic protection agent, converts the dense crystal into loose particles to facilitate filtration, and complexes free heavy metals to reduce toxicity. At the same time, the secondary hydrolysis composite enzyme is used to target cleavage of residual long-chain polypeptides, which are converted into small molecular polypeptides and free amino acids that are easy to be absorbed by plants. The preparation method connects the neutralization and heat release with constant temperature enzyme hydrolysis in series, and the clear liquid product is obtained through heat-killing enzyme and two-stage fine filtration. The fertilizer is stable in physical properties, easy to absorb nutrients, and suitable for plant foliar spraying or drip irrigation fertilization in high-hardness water quality.

Description

Technical Field

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

[0002] Extracting amino acids from the protein of diseased or dead livestock and poultry to produce fertilizer is a common method for the harmless treatment of agricultural waste, currently employing an acid hydrolysis process. The resulting amino acid stock solution has a low pH, typically between 1.0 and 1.5, requiring the addition of alkaline substances for neutralization and adjustment before fertilizer production. However, during the direct addition of alkali, the neutralization reaction increases the salt concentration in the system, leading to saturation and the formation of hard crystals. These crystals not only trap and remove some nutrients but also complicate subsequent filtration, easily clogging the filter.

[0003] Regarding the composition of the concentrate, due to the limited degradation capacity of acid hydrolysis, the concentrate usually contains some incompletely degraded long-chain peptides and free heavy metal ions. These free heavy metals come into direct contact with crops during fertilizer application, easily causing toxicity. Furthermore, because of their large molecular weight, long-chain peptides have difficulty penetrating plant leaves and stomata for absorption, making it difficult for crops to truly utilize these nutrients.

[0004] In practical agricultural applications, water-soluble fertilizers are often used in conjunction with drip irrigation systems. When the water source used for fertilization is hard groundwater containing a high amount of calcium and magnesium ions, the components in conventional fertilizers easily combine with the calcium and magnesium ions in the water, forming insoluble precipitates. These precipitates, after entering the drip irrigation system with the water flow, tend to accumulate at the thin tubes and drippers, causing blockages in the drip irrigation equipment and affecting normal fertilization operations. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an amino acid water-soluble fertilizer, its preparation method, and its application. It solves the problems in existing technologies, such as the easy formation of hard crystals in the highly acidic animal protein hydrolysate during neutralization with alkali, leading to filtration difficulties; the toxicity of free heavy metals in the concentrate; the difficulty in absorption of long-chain polypeptides by plants; and the tendency of fertilizers to form precipitates and clog pipe networks in hard water drip irrigation.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides an amino acid water-soluble fertilizer, which is made from raw materials comprising the following parts by weight: 1000 parts of hydrolyzed amino acid stock solution of diseased and dead livestock protein with an initial pH of 1.0-1.5; 5-15 parts of crystal form regulator and dynamic protectant; an alkaline neutralizer, wherein the amount of alkaline neutralizer added is sufficient to stabilize the pH of the mixed system formed by mixing the hydrolyzed amino acid stock solution of diseased and dead livestock protein with the crystal form regulator and dynamic protectant to 4.0-6.0; and 1-5 parts of secondary hydrolysis complex enzyme. The crystal form regulator and dynamic protectant regulates the morphology of the primary crystal nuclei of inorganic salts during the acid-adjusting and neutralization process, causing the primary crystal nuclei of inorganic salts to form a porous microparticle structure, and performs in-situ complexation and shielding of free heavy metal ions through the dynamic dissociation of polymer groups; the secondary hydrolysis complex enzyme targets and cleaves long-chain polypeptides in the neutralized bottom liquid environment, converting them into small molecule polypeptides and free amino acids.

[0007] By employing the above technical solution, when an alkaline neutralizing agent is added to a strongly acidic stock solution to induce a neutralization reaction, the concentration of sulfate or hydrochloride in the system will reach a supersaturated state, precipitating primary crystal nuclei. The long polymer chains of the crystal form regulator and dynamic protectant are adsorbed onto the growth surface of the inorganic salt crystal nuclei through electrostatic and intermolecular forces, hindering the regular growth of the crystal lattice along its original direction. This surface adsorption alters the free energy of the crystal, causing lattice distortion and transforming dense crystalline blocks into loosely structured particles with internal pores. Simultaneously, as the pH of the system gradually increases, the acidic groups on the polymer chains of the protectant dissociate, generating anionic coordination sites. These coordination sites coordinate with free heavy metal ions in the stock solution, forming water-soluble macromolecular complexes that bind the heavy metal ions within the molecular chain network, reducing their biotoxic activity in their free state. Regarding the role of the secondary hydrolytic complex enzyme, the enzymatic reaction is initiated when the system enters a moderately acidic environment.

[0008] Preferably, the crystal form regulating and dynamic protective agent is composed of potassium polyaspartate powder and potassium lignosulfonate in a mass ratio of 1:1 to 1:3; the weight average molecular weight of the potassium polyaspartate powder is 2000 to 5000.

[0009] By employing the above technical solution, due to the differences in molecular structure between potassium polyaspartate and potassium lignosulfonate, a synergistic effect is produced when the two are used together. After mixing, the carboxyl and sulfonic acid groups dissociate sequentially at different pH values, forming a sustained complexing ability over a wide pH range.

[0010] Preferably, the secondary hydrolysis complex enzyme is prepared by physically mixing animal protein hydrolytic endopeptidase and feather / hair hydrolytic exopeptidase in dry powder form for 30 minutes, wherein the ratio of enzyme activity units of the animal protein hydrolytic endopeptidase to the feather / hair hydrolytic exopeptidase is 2:1 to 3:1; and the total enzyme activity units of the secondary hydrolysis complex enzyme are 70,000 U / g to 90,000 U / g.

[0011] By employing the above technical solution, animal protein hydrolytic endopeptidase will cleave the peptide bonds of specific amino acid residues inside the polypeptide chain, shortening the long chain macromolecule and exposing new free end groups; subsequently, feather and hair hydrolytic exopeptidase will act on these newly generated end groups, removing amino acid residues one by one from both ends of the polypeptide chain.

[0012] Preferably, the alkaline neutralizing agent is selected from calcium hydroxide powder, potassium hydroxide, or a suspension formed by premixing ammonia water and magnesium hydroxide; the raw material also contains 0 to 30 parts of excipients, which are composed of boric acid and zinc sulfate heptahydrate powder mixed in equal mass ratio.

[0013] By employing the above technical solution, the alkaline neutralizing agent can adjust the pH while also supplementing the alkaline earth metal nutrients required by plants. Boric acid in the excipients provides boron nutrition, and zinc sulfate heptahydrate provides zinc nutrition. In a system containing free amino acids, boron and zinc trace elements undergo a chelation reaction with the amino groups in the amino acid molecules, forming polycyclic amino acid trace element chelates.

[0014] Secondly, the present invention provides a method for preparing an amino acid water-soluble fertilizer, comprising the following steps: pumping the hydrolyzed amino acid stock solution of diseased and dead livestock and poultry protein into a reaction vessel; adding the crystal form regulator and dynamic protectant under stirring conditions, mixing evenly to ensure uniform distribution of the crystal form regulator and dynamic protectant in a strong acid system; maintaining stirring, slowly adding the alkaline neutralizing agent into the vessel to carry out a neutralization exothermic reaction; stopping the addition of alkali when the pH value of the system reaches 4.0-6.0, and then cooling and maintaining a constant temperature to obtain the liquid in the vessel; adding the secondary hydrolysis complex enzyme to the liquid in the vessel, and carrying out a secondary enzymatic hydrolysis reaction under constant temperature stirring conditions to obtain the liquid; heating the liquid to thermally denature and inactivate the secondary hydrolysis complex enzyme, and then performing primary pre-filtration while hot; introducing the filtrate obtained from the primary pre-filtration into a microporous filtration system for pressure fine filtration, and collecting the homogeneous clear filtrate that has passed through the filter membrane to obtain the amino acid water-soluble fertilizer.

[0015] By adopting the above technical solution, the timing of material introduction and the control of the reaction environment were clarified. The protective agent is dispersed in an acidic environment beforehand, allowing it to occupy space within the system before the formation of inorganic salts. During this process, the heat released by acid-base neutralization raises the system temperature, providing the initial environment for the subsequent enzymatic hydrolysis process. At the end of the reaction, the heating operation disrupts the protein spatial conformation of the complex enzyme, causing it to lose its catalytic activity and thus terminating the reaction. The high temperature also reduces the kinematic viscosity of the liquid. The liquid, in its low-viscosity state, can separate modified loose microparticles and other solid impurities when passing through a two-stage filtration device, obtaining a uniform and transparent liquid product.

[0016] Preferably, the uniformly distributed stirring and mixing temperature is 15 to 25°C, and the mixing time is 15 to 20 minutes; the cooling and stabilization operation of the liquid in the reactor is as follows: the temperature of the liquid in the reactor after the neutralization exothermic reaction is reduced to and stabilized at 30 to 50°C; the temperature of the secondary enzymatic hydrolysis reaction of the liquid is stabilized at 30 to 50°C, and the hydrolysis time is 4.0 to 5.0 hours; the operation of thermally denaturing and inactivating the secondary hydrolysis complex enzyme is as follows: the reactor temperature is raised to 80 to 100°C and maintained for 15 to 30 minutes.

[0017] By employing the above technical solution, the established thermodynamic range helps ensure the reaction proceeds. Lowering the temperature and maintaining it at 30 to 50°C provides suitable conditions for the catalytic reaction of the complex enzyme.

[0018] Preferably, the primary pre-filtration and pressurized fine filtration are implemented as follows: while the compound enzyme has been denatured and inactivated, the liquid is subjected to primary pre-filtration through a stainless steel mesh with a pore size of 30 to 50 mesh; the filtrate obtained from the primary pre-filtration is pumped into a buffer mixing tank; when the raw material contains excipients, the excipients are added to the buffer mixing tank, and the mixture is stirred continuously for 15 to 20 minutes until the excipients are completely dissolved before being introduced into an automatic backwashing microporous filtration system or a microporous filtration system; the working fluid pressure is set to 0.3 to 0.5 MPa, so that the filtrate obtained from the primary pre-filtration passes through a microporous membrane assembly with a pore size of 60 to 100 mesh for pressurized fine filtration.

[0019] By adopting the above technical solution, a multi-stage separation and filtration process is used. The 30-50 mesh pre-filtration removes larger insoluble particles, while the 60-100 mesh microporous filtration system performs pressurized fine filtration at a set fluid pressure of 0.3-0.5 MPa. This further effectively removes fine suspended particles and modified loose microparticles, ensuring that the final collected homogeneous and clear filtrate passes through the filtration membrane. This meets the requirement that high-quality water-soluble fertilizers will not clog pipe networks and nozzles in subsequent spraying or drip irrigation applications.

[0020] Preferably, the crystal form regulating and dynamic protective agent uses raw materials including potassium polyaspartate, which is obtained through the following pre-preparation steps: L-aspartic acid powder is placed in a vacuum reactor and subjected to thermal polycondensation reaction at 180 to 220°C for 1.5 to 2.5 hours to generate intermediate polysuccinimide; the intermediate polysuccinimide is suspended in deionized water, and a 10% to 15% potassium hydroxide aqueous solution is slowly added dropwise at 60 to 70°C to carry out a ring-opening reaction, maintaining the pH of the system at 8.0 to 9.0, and the reaction is continued for 1 to 2 hours, and finally the potassium polyaspartate powder is obtained by evaporation and drying.

[0021] By employing the above-mentioned technical solution, the synthesis of the target polymer involves two chemical reactions. The first stage is a thermal condensation dehydration reaction, in which the amino and carboxyl groups of L-aspartic acid monomer molecules undergo dehydration condensation to form a closed-ring polysuccinimide molecular chain; the second stage is an alkaline hydrolysis ring-opening reaction, in which hydroxide ions attack the carbon-nitrogen bonds on the succinimide ring, causing the ring structure to open and forming a straight-chain polyaspartic acid potassium.

[0022] Thirdly, the present invention provides an application of an amino acid water-soluble fertilizer in foliar spraying or drip irrigation fertilization in high-hardness water. The application includes the following specific application methods: diluting and mixing the amino acid water-soluble fertilizer with water and then spraying it evenly on the plant leaves; or injecting the amino acid water-soluble fertilizer into a drip irrigation fertilization system in high-hardness water and applying it with the drip irrigation water. The crystal form regulating and dynamic protective agent in the amino acid water-soluble fertilizer complexes and shields calcium and magnesium ions in high-hardness irrigation water and inhibits the precipitation of insoluble salts, thereby preventing blockage of the drip irrigation network.

[0023] By adopting the above technical solutions, this fertilizer can adapt to more complex agricultural operation scenarios. When mixed with hard groundwater rich in calcium and magnesium ions for drip irrigation, the crystal form regulators and dynamic protectants in the fertilizer are reused. The polar functional groups on the polymer chains combine with free calcium and magnesium ions in the aqueous phase to form coordination compounds. This changes the probability of carbonate and sulfate ions combining with calcium and magnesium ions in the water, reducing the saturation of precipitated salts. The polymer chains adsorbed on the microcrystalline nuclei increase the negative charge density on the particle surface, relying on electrostatic repulsion to prevent the crystals from agglomerating into large-particle scale layers, thereby maintaining the unobstructed flow of the drip irrigation network and the dripper orifices.

[0024] This invention provides an amino acid water-soluble fertilizer, its preparation method, and its application. It has the following beneficial effects: 1. This invention adds a crystal form regulator and dynamic protectant to an acidic stock solution. Through the adsorption of long polymer chains onto the surface of newly formed inorganic salt crystal nuclei, it alters their growth state and induces lattice distortion, transforming the originally easily formed hard crystalline blocks into loose microparticles, thus reducing the resistance to subsequent filtration. As the pH of the system rises after the addition of alkali, the protectant dissociates and releases coordination sites, binding with free heavy metals in the system and confining them within the polymer network, reducing toxicity to plants. Simultaneously, when using high-hardness water for drip irrigation, it can also bind with calcium and magnesium ions in the water, preventing precipitation and clogging of the pipe network.

[0025] 2. This invention employs a two-stage hydrolysis complex enzyme composed of a mixture of endopeptidases and exopeptidases in a specific ratio to degrade polypeptides in the neutralized fertilizer solution. First, the endopeptidases break the peptide bonds within the polypeptide chains, shortening the long chains. Then, the exopeptidases cleave the amino acid residues one by one from the newly generated end groups. This continuous enzymatic hydrolysis process transforms long-chain polypeptides, which are difficult for plants to directly absorb, into small-molecule polypeptides and free amino acids, making it easier for nutrients in the fertilizer to pass through plant leaves and stomata for absorption and utilization.

[0026] 3. The preparation method combines material mixing, acid-base neutralization, and enzymatic hydrolysis in a series. The heat generated by the exothermic neutralization reaction directly meets the temperature requirements for subsequent enzymatic hydrolysis, reducing additional heating operations. After enzymatic hydrolysis, the reaction is terminated by inactivating the complex enzyme through heating. Taking advantage of the good fluidity of the liquid at high temperatures, a two-stage filtration process using a stainless steel mesh and microporous membrane separates the modified suspended particles, ultimately yielding a uniform and clear liquid product. Attached Figure Description

[0027] Figure 1 This is a line graph showing the evolution of the concentration of ionized zinc ions at different pH values ​​during the acid-adjusting and neutralization process of this invention. Figure 2 This is a graph showing the settling kinetics of the acid-neutralized product of this invention. Figure 3 This is a graph showing the nitrogen conversion kinetics of the secondary hydrolysis system of this invention. Figure 4 This is a comparison diagram of the flux attenuation kinetics of pressurized microporous filtration in this invention; Figure 5 This is a kinetic curve of the anti-flocculation of the diluted water-soluble fertilizer solution under high hardness water conditions according to the present invention; Figure 6 This is a diagram illustrating the transmembrane absorption kinetics of plant leaves in this invention. Figure 7 Figure 1 shows the dynamic concentration comparison distribution of trace elements under simulated phosphorus-containing antagonistic environment in this invention. Figure 2 shows the change in effective zinc concentration and Figure 3 shows the change in effective boron concentration. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Preparation Examples 1-5: Preparation Example 1: This preparation example provides a method for preparing a crystal form regulating and dynamic protective agent, including the following steps: L-Aspartic acid powder was placed in a vacuum reactor and subjected to thermal polycondensation at 180°C for 1.5 hours to generate the intermediate polysuccinimide. The intermediate polysuccinimide was suspended in deionized water, and a 10% (w / w) potassium hydroxide aqueous solution was slowly added dropwise at 60°C to initiate a ring-opening reaction. The pH of the system was maintained at 8.0, and the reaction was continued for 1 hour. After evaporation and drying, potassium aspartate powder with a weight-average molecular weight of 2000 was obtained. The obtained potassium aspartate powder and potassium lignosulfonate were added to a mixer at a mass ratio of 1:1 and physically mixed uniformly at room temperature to obtain a crystal form regulator and dynamic protectant.

[0030] Preparation Example 2: This preparation example provides a method for preparing a crystal form regulating and dynamic protective agent, including the following steps: L-Aspartic acid powder was placed in a vacuum reactor and subjected to thermal polycondensation at 200°C for 2.0 hours to generate the intermediate polysuccinimide. The intermediate polysuccinimide was suspended in deionized water, and a 12% (w / w) potassium hydroxide aqueous solution was slowly added dropwise at 65°C to initiate a ring-opening reaction. The pH of the system was maintained at 8.5, and the reaction was continued for 1.5 hours. After evaporation and drying, potassium aspartate powder with a weight-average molecular weight of 3500 was obtained. The obtained potassium aspartate powder and potassium lignosulfonate were added to a mixer at a mass ratio of 1:2 and physically mixed uniformly at room temperature to obtain a crystal form regulator and dynamic protectant.

[0031] Preparation Example 3: This preparation example provides a method for preparing a crystal form regulating and dynamic protective agent, including the following steps: L-Aspartic acid powder was placed in a vacuum reactor and subjected to thermal polycondensation at 220°C for 2.5 hours to generate the intermediate polysuccinimide. The intermediate polysuccinimide was suspended in deionized water, and a 15% (w / w) potassium hydroxide aqueous solution was slowly added dropwise at 70°C to initiate a ring-opening reaction. The pH of the system was maintained at 9.0, and the reaction was continued for 2 hours. After evaporation and drying, potassium aspartate powder with a weight-average molecular weight of 5000 was obtained. The obtained potassium aspartate powder and potassium lignosulfonate were added to a mixer at a mass ratio of 1:3 and physically mixed uniformly at room temperature to obtain a crystal form regulator and dynamic protectant.

[0032] Preparation Example 4: This preparation example provides a method for preparing a secondary hydrolysis complex enzyme, including the following steps: At a low temperature of 4℃, animal protein hydrolytic endopeptidase and feather and hair hydrolytic exopeptidase were added to a homogenizing mixer at a ratio of 2:1 and the dry powder was physically mixed for 30 minutes to obtain a secondary hydrolytic complex enzyme. The total enzyme activity of the complex was measured to be in the range of 70,000 U / g to 90,000 U / g.

[0033] Preparation Example 5: This preparation example provides a method for preparing a secondary hydrolysis complex enzyme, including the following steps: At a low temperature of 8℃, animal protein hydrolytic endopeptidase and feather and hair hydrolytic exopeptidase were added to a homogenizing mixer at a ratio of 3:1 and the dry powder was physically mixed for 30 minutes to obtain a secondary hydrolytic complex enzyme. The total enzyme activity of the complex was measured to be in the range of 70,000 U / g to 90,000 U / g.

[0034] Examples 1-4: Example 1: This embodiment provides a method for preparing an amino acid water-soluble fertilizer, including the following steps: 1000 kg of hydrolyzed amino acid stock solution of diseased and dead livestock and poultry protein with an initial pH of 1.2 was pumped into a stainless steel reactor equipped with a jacketed temperature control and mechanical stirring device. At a stirring speed of 120 r / min, 10 kg (mass fraction of 1.0%) of the crystal form regulator and dynamic protectant prepared in Preparation Example 2 was added to the stock solution.

[0035] The mixture was stirred continuously at 20°C for 18 minutes to ensure uniform distribution of the polymer crystal form regulator and dynamic protectant in the strong acid system. While maintaining stirring, approximately 285 kg of calcium hydroxide powder was slowly added to the reactor to initiate a neutralization exothermic reaction. The pH value of the system was monitored in real time, and the addition of alkali was stopped when the pH value stabilized at 5.0. The cooling water circulation system of the reactor jacket was activated, and the temperature of the liquid in the reactor was reduced to and stabilized at 40°C within 25 minutes. Subsequently, 3 kg (0.3% by mass) of the secondary hydrolytic complex enzyme prepared in Preparation Example 4 was added.

[0036] A secondary enzymatic hydrolysis reaction was carried out at 40℃ with continuous stirring for 4.5 hours. After hydrolysis, the cooling water was turned off, and steam heating was turned on to raise the reactor temperature to 90℃ within 12 minutes and maintain it for 20 minutes, causing the complex enzyme to be thermally denatured and inactivated. While still hot, the solution was passed through a 40-mesh stainless steel mesh for primary pre-filtration. The filtrate was pumped into a buffer mixing tank, stirred for 15 minutes, and then introduced into an automatic backwashing microporous filtration system. The working fluid pressure was set to 0.4 MPa, allowing the solution to pass through an 80-mesh microporous membrane assembly for pressurized fine filtration. The homogeneous, clear filtrate that passed through the membrane was collected and bottled to obtain the amino acid water-soluble fertilizer.

[0037] Example 2: This embodiment provides a method for preparing an amino acid water-soluble fertilizer, including the following steps: 1000 kg of hydrolyzed amino acid stock solution of diseased and dead livestock protein with an initial pH of 1.0 was pumped into a stainless steel reactor. 5 kg (0.5% by mass) of the crystal form regulator and dynamic protectant prepared in Preparation Example 1 was added to the stock solution while stirring at 100 r / min.

[0038] The mixture was stirred continuously at 15°C for 15 minutes. While maintaining stirring, approximately 90 kg of potassium hydroxide was slowly added to the reactor to initiate an exothermic neutralization reaction. The pH value of the system was monitored in real time, and the addition of alkali was stopped when the pH value stabilized at 4.0. The cooling water in the reactor jacket was turned on, and the temperature of the liquid in the reactor was reduced to and maintained at 30°C within 20 minutes. Subsequently, 1 kg (0.1% by mass) of the secondary hydrolytic complex enzyme prepared in Preparation Example 5 was added.

[0039] A secondary enzymatic hydrolysis reaction was carried out at 30℃ with continuous stirring for 4.0 hours. After hydrolysis, the reactor temperature was raised to 80℃ and maintained for 15 minutes. While still hot, the liquid was passed through a 30-mesh stainless steel mesh for primary pre-filtration. The filtrate was pumped into a buffer mixing tank, stirred for 15 minutes, and then introduced into a microfiltration system. The working fluid pressure was set to 0.3 MPa, allowing the liquid to pass through a 60-mesh microporous membrane assembly for pressurized fine filtration. The filtrate was collected and bottled to obtain the amino acid water-soluble fertilizer.

[0040] Example 3: This embodiment provides a method for preparing an amino acid water-soluble fertilizer, including the following steps: 1000 kg of hydrolyzed amino acid stock solution of diseased and dead livestock and poultry protein with an initial pH of 1.5 was pumped into a stainless steel reactor. 15 kg (1.5% by mass) of the crystal form regulator and dynamic protectant prepared in Preparation Example 3 was added to the stock solution while stirring at 150 r / min.

[0041] The mixture was stirred continuously at 25°C for 20 minutes. While maintaining stirring, a suspension premixed from approximately 350 kg of ammonia and approximately 200 kg of magnesium hydroxide was slowly added to the reactor to initiate a neutralization and exothermic reaction. The pH value of the system was monitored in real time, and the addition of alkali was stopped when the pH value stabilized at 6.0. The cooling water in the reactor jacket was turned on, and the temperature of the liquid in the reactor was reduced to and maintained at 50°C within 30 minutes. Subsequently, 5 kg (0.5% by mass) of the secondary hydrolytic complex enzyme prepared in Preparation Example 4 was added.

[0042] A secondary enzymatic hydrolysis reaction was carried out at 50℃ with continuous stirring for 5.0 hours. After hydrolysis, the reactor temperature was raised to 100℃ and maintained for 30 minutes. While still hot, the liquid was passed through a 50-mesh stainless steel mesh for primary pre-filtration. The filtrate was pumped into a buffer mixing tank, stirred for 20 minutes, and then introduced into a microfiltration system. The working fluid pressure was set to 0.5 MPa, allowing the liquid to pass through a 100-mesh microporous membrane assembly for pressurized fine filtration. The filtrate was collected and bottled to obtain the amino acid water-soluble fertilizer.

[0043] Example 4: This embodiment provides a method for preparing an amino acid water-soluble fertilizer, including the following steps: 1000 kg of hydrolyzed amino acid stock solution of diseased and dead livestock and poultry protein with an initial pH of 1.2 was pumped into a stainless steel reactor. 10 kg (1.0% by mass) of the crystal form regulator and dynamic protectant prepared in Preparation Example 2 was added to the stock solution while stirring at 120 r / min.

[0044] The mixture was stirred continuously at 20°C for 18 minutes. While maintaining stirring, approximately 285 kg of calcium hydroxide powder was slowly added to the reactor, and the pH value of the system was monitored in real time. When the pH value stabilized at 5.0, the addition of alkali was stopped. The temperature of the solution was lowered and kept constant at 40°C. 3 kg (0.3% by mass) of the secondary hydrolytic complex enzyme prepared in Preparation Example 4 was added.

[0045] A secondary enzymatic hydrolysis reaction was carried out at 40℃ for 4.5 hours. The reactor temperature was then increased to 90℃ and maintained for 20 minutes. The liquid was pre-filtered through a 40-mesh stainless steel mesh, and the filtrate was pumped into a buffer mixing tank. 30 kg (3.0% by mass) of an auxiliary material consisting of boric acid and zinc sulfate heptahydrate powder mixed in equal mass ratio was added to the pre-filtrate in the buffer mixing tank, and the mixture was stirred continuously for 20 minutes until the auxiliary material was completely dissolved. Subsequently, the mixture was introduced into a microporous filtration system, and the working fluid pressure was set to 0.4 MPa, allowing the liquid to pass through an 80-mesh microporous filter membrane assembly for pressurized fine filtration. The filtrate was collected and bottled to obtain a water-soluble fertilizer rich in trace elements and amino acids.

[0046] Comparative Examples 1-4: Comparative Example 1: Compared with Example 1, the difference is that no crystal form regulator and dynamic protectant are added in step 1, while the rest are the same.

[0047] Comparative Example 2: Compared with Example 1, the difference is that in step 1, only the same mass of potassium polyaspartate powder is added to replace the crystal form regulator and dynamic protectant; all other aspects are the same.

[0048] Comparative Example 3: Compared with Example 1, the difference is that crystal form regulator and dynamic protectant are not added in step 1, but are added after the pH value of the system stabilizes at 5.0 in step 2. All other aspects are the same.

[0049] Comparative Example 4: Compared with Example 1, the difference is that no secondary hydrolysis complex enzyme is added in step 3, and no secondary enzymatic hydrolysis reaction is performed; all other aspects are the same.

[0050] Comparative Example 5: Compared to Example 4, the difference is that no auxiliary materials were added when preparing the main body of the amino acid water-soluble fertilizer. After finally collecting the homogeneous clear filtrate of Example 1, 30 kg of boric acid and zinc sulfate heptahydrate powder were directly and physically mixed into the filtrate at room temperature in equal mass ratio, and simply stirred until dissolved to obtain a physical mixture of free trace elements and amino acids, with all other conditions being the same.

[0051] Test Examples 1-6: Test Example 1: Verify the pH response characteristics and free heavy metal shielding ability of the polymer composition.

[0052] The solutions from the acidification and neutralization stages of the preparation process in Example 1 and Comparative Example 1 were selected as experimental subjects. During the gradual addition of alkaline acidifying agent into the reactor, the pH was monitored using an online pH meter. 50 mL of the mixed solution was extracted via a sampling valve when the pH reached 1.2, 2.0, 3.0, 4.0, and 5.0, respectively.

[0053] Immediately transfer the mixed liquid obtained from each sampling point into centrifuge tubes and centrifuge at 8000 r / min for 15 min to allow the primary crystals and unreacted suspended impurities generated by the reaction to settle to the bottom of the tube. Then, extract the clear liquid from the top layer for subsequent determination.

[0054] Take an appropriate amount of the supernatant after centrifugation, add a buffer solution to adjust the test environment, then add dithizone colorimetric reagent, and measure the absorbance of the solution at a specific wavelength using a spectrophotometer. Combined with a pre-plotted standard curve, calculate the absolute concentration of free zinc ions in the feed system at each stage.

[0055] The concentration data of free zinc ions measured at each sampling point are summarized in the table below.

[0056] Table 1. Determination of ionic zinc ion concentration (mg / L) at different pH values ​​during acidification and neutralization process.

[0057] Figure 1 The solid lines with solid dots represent the concentration decay trajectory of Example 1 with added crystal form regulator and dynamic protectant, while the dashed lines with hollow squares represent the concentration decay trajectory of Comparative Example 1 without added component in the same pH range.

[0058] According to Table 1 and Figure 1The trend of the curve shows a divergence between the system's performance under initial strong acid conditions and its dynamic evolution during acidification. When the system is in the strong acid stage (pH 1.2), the free zinc ion concentrations measured in Example 1 and Comparative Example 1 are similar, both remaining above 150 mg / L. This indicates that under extremely low pH conditions, the carboxyl groups of polyaspartic acid and lignin sulfonate exist in the dispersion in a protonated form. Since the functional groups are not dissociated at this point, the polymer composition exhibits a zero-complexation state for heavy metal ions, making it less prone to entanglement and aggregation, thus facilitating physical pre-dispersion. As the neutralization reaction proceeds, the pH of the system increases. Observing the data trajectory of Example 1, as the pH reaches 3.0 and continues to rise to 5.0, the free zinc ion concentration drops significantly, falling to 16.4 mg / L. Compared to the flatter data decay curve of Comparative Example 1, this concentration decrease is not entirely due to the precipitation of inorganic salts. In Comparative Example 1, the concentration of free zinc ions in the system remained as high as 122.1 mg / L even at pH 5.0. This indicates that the slight concentration decrease without crystal form control and dynamic protection agents originates from the adsorption of primary zinc hydroxide crystal nuclei or a small amount of precipitation caused by localized over-alkaliness. The decrease in free ions in Example 1 reflects the dynamic dissociation and activation behavior of polymeric functional groups as pH increases. The dissociated carboxylate and other groups complex with free heavy metal ions. This complexation effect, which occurs with pH changes, reduces the toxicity of free heavy metals to subsequent enzymatic hydrolysis.

[0059] Test Example 2: Verify the morphology and sedimentation characteristics of the acid-neutralization products.

[0060] The homogeneous suspension formed in the reactor at the end of the acidification and neutralization stage of Example 1 and Comparative Example 1 was extracted as test samples. The extraction operation was carried out after the temperature dropped to 40°C and stabilized.

[0061] A small amount of pretreated sample was transferred into the test channel of the laser particle size analyzer. Deionized water was used as the dispersion medium to adjust the background shading of the instrument. The detection program was run to obtain the median particle size D50 data of the suspended products in the system.

[0062] Accurately measure 100 mL of the above suspension solution and transfer it into a standard 100 mL glass graduated measuring cylinder. Seal the opening of the cylinder with sealing film to prevent moisture evaporation.

[0063] Place the graduated cylinder on a horizontal experimental platform and let it stand. Record the scale values ​​of the solid-liquid separation interface at the bottom of the graduated cylinder at 15 min, 30 min, 60 min, 90 min and 120 min respectively, and obtain the apparent volume of sediment corresponding to different time periods.

[0064] The measured particle size parameters and sedimentation dynamic volume data are summarized in the table below.

[0065] Table 2. Results of median particle size and sedimentation volume of acid-adjusting and neutralization products at different standing times.

[0066] Figure 2 The solid line marked with a solid equilateral triangle represents the sedimentation volume trajectory of the suspension in Example 1 over time, while the dotted line marked with a hollow rhombus represents the sedimentation volume trajectory of the suspension in Comparative Example 1 without the addition of modified components.

[0067] Based on the data in Table 2 and Figure 2 The dynamic curves show that the precipitates generated in Example 1 and Comparative Example 1 during the acidification and neutralization stages exhibit different physical morphologies and sedimentation characteristics. Laser particle size analysis results show that the median particle size of Comparative Example 1 is only 4.8 μm. Observation of the static sedimentation process revealed that the sedimentation boundary of the colloid was blurred after 15 minutes, with a volume of 96.1 mL. Figure 2 The sedimentation trajectory shows that as the system's settling time increased to 120 min, the colloid agglomerated and gradually compacted, shrinking its apparent volume to 22.1 mL. The median particle size of the product in Example 1 was 45.6 μm. This is because the polymer targeted adsorption onto specific crystal faces of the primary crystal nuclei of inorganic salts such as calcium sulfate, altering the disordered agglomeration of the crystal lattice and causing the newly formed particles to form microparticles with spatial structures. The sedimentation curve over time shows that these microparticles can form a stable sedimentation interface, with an initial sedimentation volume of 89.2 mL at 15 min, lower than that of Comparative Example 1 at the same time. However, the subsequent decline in the sedimentation volume curve of Example 1 was gradual, exceeding the colloid volume within the 30-60 min range, and after 120 min of settling, its final substrate still maintained an apparent volume of 56.4 mL. These results reflect that the fine particles in Example 1 supported each other and stacked, retaining internal pores. During pressure filtration, the porous structure maintains support, facilitating the penetration of water-soluble amino acid molecules and reducing membrane clogging.

[0068] Test Example 3: To verify the targeted cleavage ability and hydrolysis kinetics evolution of the secondary hydrolytic complex enzyme in the treated substrate system.

[0069] The feed solutions from the secondary hydrolysis stage of Example 1 and Comparative Example 4 were selected as the analysis objects. Under constant temperature stirring at 40°C in the reactor, 150 mL of mixed fluid was drawn out through the sampling valve on the side wall of the reactor at 0, 1.0, 2.0, 3.0 and 4.5 hours after the addition of the compound enzyme (the corresponding initial heat preservation time for Comparative Example 4).

[0070] The extracted fluid was immediately transferred to a constant temperature water bath at 95°C and heated continuously for 15 minutes to force the biochemical enzymes in the liquid system to undergo thermal denaturation and complete inactivation. By physically blocking the hydrolysis process, the data status at the corresponding time point was accurately locked. Then, it was placed in an ice-water bath to cool to room temperature for testing.

[0071] Accurately transfer an appropriate amount of the cooled supernatant sample and perform digestion titration using a Kjeldahl nitrogen analyzer to determine the total nitrogen concentration in the liquid sample. Simultaneously, take supernatant samples from the same batch, add neutral formaldehyde reagent to mask the amino groups at the ends of free amino acid molecules, and perform potentiometric titration using standard sodium hydroxide solution under pH monitoring. Calculate the mass concentration of free amino acid nitrogen based on the amount of alkali consumed.

[0072] The free amino acid nitrogen concentration calculated at each test time point is divided by the total nitrogen concentration of the same system to obtain the mass percentage of free amino acid nitrogen in the total nitrogen.

[0073] The amino acid nitrogen percentage data measured at each sampling point are summarized in the table below.

[0074] Table 3. Results of determination of the proportion of free amino acid nitrogen in total nitrogen at different hydrolysis times (%)

[0075] Figure 3 The solid lines marked with solid pentagrams represent the evolution of the proportion of free amino acid nitrogen over time in the system of Example 1 with the introduction of secondary hydrolytic complex enzyme, while the dashed lines marked with hollow hexagons represent the transformation trajectory of Comparative Example 4 without added hydrolytic enzyme under the same temperature control conditions.

[0076] Based on the data in Table 3 and Figure 3 The kinetic trajectory revealed that the nutrient transformation of the substrate system had reached a bottleneck after initial strong acid treatment, and the addition of the complex enzyme promoted substrate hydrolysis. In the initial 0-hour stage of the reaction, the proportion of free amino acid nitrogen in both test groups remained around 32% (32.4% in Example 1 and 32.1% in Comparative Example 4). Comparative Example 4, after undergoing a 4.5-hour isothermal reaction, showed... Figure 3The transformation trajectory is represented by a flat dashed line, with the proportion of free amino acid nitrogen fluctuating but remaining around 33.9%, indicating that the hydrolysis effect solely relying on residual acid has essentially ceased. In a substrate containing salt and heavy metals, the enzyme easily loses its catalytic ability. The continuous transformation in Example 1 is attributed to the high-molecular-weight complexation system in the initial stage reducing the adverse environmental impact on the enzyme. The curve trend shows that the proportion of free amino acid nitrogen in Example 1 increases in the first two hours after enzyme addition, reaching 49.3% by the 1st hour and exceeding 60% (specifically 62.1%) by the 2nd hour. As hydrolysis continues, this proportion continues to rise to 75.6% by the 3rd hour and reaches 85.2% at the end of the reaction. This is because the endopeptidase cleaves the long peptide chain, releasing the polypeptide terminus; the exopeptidase then strips free amino acids, completing the degradation of the short peptide.

[0077] Test Example 4: To verify the effect of composite polymer composition on microstructure control in industrial pressurized environments, and the practical engineering role of this control in solving the problem of fluid film blockage.

[0078] The homogeneous buffer solutions from Examples 1 and 2, as well as Comparative Examples 1, 2, and 3, after primary pre-filtration, were used as test fluids. All sample solutions were kept at the same temperature to eliminate errors in liquid viscosity caused by temperature differences.

[0079] The aforementioned liquid samples were pumped into a small-scale pressure filtration test system equipped with a standard 80-mesh stainless steel microporous filter membrane module. The air compressor was turned on to adjust the system's operating conditions, ensuring that the pressure of the filtration working fluid was maintained at a constant 0.4 MPa.

[0080] The zero-point time of filtration start was recorded by opening the outlet valve. The volume of clear filtrate permeating the membrane was collected and measured at 5 min, 15 min, 30 min, 60 min, 90 min, and 120 min of continuous pressurized filtration. The permeate flux at each time point was calculated based on the effective permeable area of ​​the membrane.

[0081] The permeability data of each group at different times under constant pressure filtration are summarized in the table below.

[0082] Table 4. Results of water permeability measurement at different times under constant pressure filtration (L / m) 2 ·h)

[0083] Figure 4The solid lines with a solid downward triangle and the solid lines with a solid rightward triangle correspond to the flux decay trajectories of Example 1 and Example 2, respectively; the dashed lines marked with a plus sign, the dotted lines marked with a cross, and the dotted lines marked with a hollow square represent the flux decay trajectories of Comparative Example 1 without a polymer protective agent, Comparative Example 2 with only a single component, and Comparative Example 3 with a changed protective agent addition sequence, respectively.

[0084] Based on the data in Table 4 and Figure 4 The displayed curves reflect the performance of the hydrolysate during pressure filtration. In Comparative Example 1, where no crystal form intervention was performed, the permeate flux reached 95.8 L / m³ just 5 minutes after the system started filtration. 2 •h. Inorganic salt precipitates in a soft colloidal state within the fluid undergo plastic deformation upon contact with the stainless steel microporous filter membrane. Under a pressure of 0.4 MPa, the colloids are forced into the micropores of the filter membrane. The membrane becomes clogged within a short time, causing the system flux to drop to 2.4 L / m³ after 60 minutes of filtration operation. 2 The permeability is measured over 90 minutes, and the permeate flux reaches zero at 90 minutes, at which point the filtration operation stops. At this point, a dense filter cake layer forms on the surface of the filter membrane, and its permeability is difficult to restore using conventional methods.

[0085] The filtration aid effect of a single polymer component in complex salt systems is limited. Comparative Example 2, with the addition of only potassium polyaspartate powder, showed an initial improved flux of 125.6 L / m³. 2 ·h, but still decreased to 4.2L / m after 120min. 2 •h. Single-component polymer segments can only provide the necessary chemical coordination sites, lacking the synergistic support of lignin sulfonate, which easily leads to the collapse of the crystalline particle structure under prolonged pressure. The test trajectory of Comparative Example 3 is in… Figure 4 The result is highly similar to Comparative Example 1, with an initial flux of 101.3 L / m³ at 5 min. 2 •h, and also encountered complete blockage at 120min (flux dropped to 0.0L / m 2 The outcome of ·h), and the sharp drop in the curve of Comparative Example 3, indirectly confirms the weight of the time sequence node in the crystal form regulation mechanism. After the bottom liquid flocs have formed, it is difficult to change their aggregated state by adding polymeric protective agents.

[0086] Compared to the control group, the fluxes in Examples 1 and 2 were more stable. With the addition of the composite polymer modifier, the initial filtration flux of the system reached as high as 186.4 L / m³. 2 ·h and 179.2L / m 2 ·h, and in Figure 4The flux exhibits a gradual decline. The targeted adsorption of functional groups on specific crystal faces of the inorganic salt primary crystal nuclei alters the crystal morphology, causing the precipitated particles to form fine crystal clusters. When these microcrystalline particles reach the surface of the microporous filter membrane under pressure differential, they overlap, forming a porous, loose filter cake layer on the membrane surface. Even after two consecutive hours of pressure filtration, the flux in Examples 1 and 2 remained at 141.9 L / m³. 2 ·h and 133.5L / m 2 The working range of h.

[0087] Test Example 5: The anti-flocculation stability and interfacial permeation characteristics of the final free amino acid product were verified under simulated high-hardness irrigation water conditions.

[0088] The high-concentration amino acid water-soluble fertilizer products finally prepared in Examples 1 and 2, as well as Comparative Examples 1 and 4, were extracted as analytical samples.

[0089] Anhydrous calcium chloride and magnesium sulfate of analytical grade were dissolved in deionized water according to the mass conversion relationship to artificially prepare standard extreme hard water with a total hardness of 1000 mg / L (calculated as calcium carbonate), thereby simulating the extremely harsh raw water environment for agricultural groundwater irrigation.

[0090] Each group of water-soluble fertilizer products was injected into the above-mentioned standard hard water at a volume ratio of 1:500. The mixture was then stirred at a magnetic stirrer at 300 rpm for 10 minutes at an ambient temperature of 25℃ to obtain the test dilution. The initial dilution from the trace mixing stage was extracted, and the dynamic contact angle data of the dilution droplets on the Teflon standard target surface were recorded using a contact angle meter.

[0091] The well-mixed diluent was transferred to a standard cuvette and placed on a light-proof experimental platform to stand. The scattering turbidity (NTU) of the system was measured using a precision turbidimeter at time points of 1 hour, 6 hours, 12 hours, 24 hours and 48 hours after standing, to obtain the dynamic evolution parameters of the particle aggregation state in the system.

[0092] The measured dynamic contact angle and turbidity data at different settling times are summarized in the table below.

[0093] Table 5. Results of final product interface contact angle and turbidity measurement under simulated hard water environment

[0094] Figure 5The solid lines marked with asterisks and the solid lines marked with hollow left-facing triangles correspond to the turbidity evolution trajectories of the fertilizer dilutions in Examples 1 and 2, respectively; the dashed lines marked with crosses and the dotted lines marked with hollow diamonds represent the turbidity evolution trajectories of the fertilizer dilutions in Comparative Example 1 (without the addition of a polymeric protective agent) and Comparative Example 4 (without secondary enzymatic hydrolysis). To clearly distinguish the curve trends in the low turbidity range, the vertical axis of this graph uses a logarithmic scale.

[0095] Based on the data in Table 5 and Figure 5 The curves shown demonstrate that the composite system and multi-stage cleavage mechanism introduced in the initial preparation process exhibit anti-flocculation effects in hard water dilution. Agricultural micro-irrigation systems have certain requirements for the solubility and purity of water-soluble fertilizers; calcium and magnesium ions in the water are prone to precipitation, leading to pipe network blockage. Observing the data from Comparative Example 1 (without intervention), its diluted solution reached a turbidity of 14.1 NTU after standing for 1 hour. With prolonged time, calcium and magnesium ions cross-linked with residual sulfate and long-chain peptides from the fertilizer, resulting in the precipitation of a large amount of slightly soluble salts and peptide flocs in the liquid phase, causing the system turbidity to rise to 257.8 NTU after 48 hours. Although Comparative Example 4 achieved protection of high molecular weight components at the front end of the process, the lack of targeted cleavage by secondary complex enzymes resulted in the presence of high molecular weight peptide structures in the bottom solution. These long peptide chains readily react with polyvalent metal ions in hard water to produce flocculation. The test results, which showed that the turbidity reached 146.5 NTU in 24 hours and rose to 204.1 NTU in 48 hours, indicate that incomplete protein hydrolysate cannot meet the application requirements of complex water quality.

[0096] Examples 1 and 2 avoided the aforementioned problems from the outset, which is related to the degree of substrate degradation and the complexing effect of the polymeric protective agent. After 48 hours of settling in hard water, the turbidity of Examples 1 and 2 was controlled at 11.3 NTU and 13.9 NTU, respectively. Figure 5 The results show a gently extending line. Potassium polyaspartate and potassium lignosulfonate, used as crystal form regulators and dynamic protectants in the initial preparation process, were not stripped from the system but were converted into the final nutrient formulation along with the supernatant. The polymer groups formed complexes with calcium and magnesium ions, reducing precipitation. Agricultural application performance can be observed from the contact angle data; compared to the 75.6° contact angle of Comparative Example 1, the initial contact angles of Examples 1 and 2 decreased to 41.8° and 44.5°, respectively.

[0097] Test Example 6: To verify the bio-absorption kinetics and actual nutrient assimilation efficiency of the final free amino acid water-soluble fertilizer product during transmembrane penetration on plant leaves.

[0098] Potted tomato seedlings (at the six-leaf stage) with consistent growth cycles and uniform growth were selected as experimental test subjects. Water-soluble fertilizer products from Examples 1 and 2, as well as Comparative Examples 1 and 4, were extracted and diluted with deionized water to the same total nitrogen concentration (1000 mg / L) to prepare standard foliar spray test solutions.

[0099] Using a micropipette, 200 μL of the test solution was evenly applied to the surface of the third and fourth true leaves of each tomato seedling, ensuring that the droplets adhered to the surface without slipping off the edges. Thirty biological replicates were set up for each treatment. All treated potted plants were transferred to an artificial climate chamber at 25°C and a constant relative humidity of 65% for further cultivation under light.

[0100] At 2, 6, 12, 24 and 48 hours after the drop-coating treatment, six test leaves from each group were randomly cut. The harvested leaves were immersed intact in centrifuge tubes containing 50 mL of elution buffer (containing 0.1% Tween-20 surfactant to disrupt interfacial tension) and placed on a constant-temperature shaker at 150 r / min for 20 min to completely elute any unabsorbed residual fertilizer components from the leaf surface into the liquid phase.

[0101] The eluent was extracted and clarified by high-speed centrifugation. The total mass of residual free amino acids and peptides in the clarified liquid was accurately determined using an automated amino acid analyzer. The amount of nutrients assimilated by the plant's internal tissues was calculated by subtracting the residual mass from the initial total mass of nutrients applied to the leaves. This amount was then divided by the initial total nutrient amount to obtain the cumulative uptake rate at that time point.

[0102] The cumulative absorption rate data of the leaves at different time points for each test group are summarized in the table below.

[0103] Table 6. Results of cumulative nutrient absorption rate of plant leaves at different absorption times (%)

[0104] Figure 6 The solid lines marked with solid circles and the solid lines marked with hollow squares correspond to the growth trajectory of leaf nutrient absorption rate in Example 1 and Example 2, respectively; the dashed lines marked with hollow upward triangles and the dotted lines marked with hollow pentagrams represent the growth trajectory of leaf absorption rate in Comparative Example 1 without the addition of polymeric protective agent and Comparative Example 4 without secondary compound enzymatic hydrolysis, respectively.

[0105] Based on the data in Table 6 and Figure 6The curves shown indicate that the hydrophobic cuticle of plant leaves has certain requirements regarding the molecular weight and wettability of foliar fertilizers. Examples 1 and 2 exhibited good nutrient absorption trends in the first 6 hours after application. Two hours after contact with the leaf surface, they reached initial nutrient absorption rates of 22.4% and 18.7%, respectively. Taking Example 1 as an example, its cumulative nutrient absorption rate rose to 47.1% after 6 hours, and further increased to 71.8% and 84.9% after 12 and 24 hours, respectively, finally reaching an assimilation level of 93.6% after 48 hours. The nutrient absorption growth trajectory of Example 2 was similar to that of Example 1, with a 48-hour nutrient absorption rate of 88.4%. This is because the complex enzyme system degrades proteins into free amino acids and small peptide fragments, which are beneficial for plant absorption and utilization.

[0106] Nutrient absorption trajectories in Comparative Examples 1 and 4 Figure 6 The results showed two curves with relatively low trends, indicating a relatively low absorption rate. Comparative Example 1 showed a nutrient absorption rate of only 6.2% in the initial 2 hours, and even after 48 hours, the absorption rate was only 36.1%, with some nutrients remaining on the leaf surface, easily causing leaf burn after water evaporation. Comparative Example 4, although maintaining fluid apparent stability with the help of a polymeric dispersant at the beginning of the process, lacked secondary enzymatic hydrolysis, resulting in large molecular weights of undegraded peptides that were not easily absorbed by leaf pores. This led to a nutrient absorption rate of only 8.9% after 2 hours, and a final absorption rate of 54.2% after 48 hours.

[0107] Test Example 7: The chelation effect of trace element excipients and free amino acids in Example 4 was verified, as well as their anti-precipitation stability in a phosphorus-containing environment.

[0108] When trace elements such as zinc and boron exist in the form of free inorganic salts, they readily combine with phosphate and hydroxide ions to form insoluble precipitates during agricultural application (especially when mixed with phosphorus-containing fertilizers or in slightly alkaline soils), leading to nutrient loss. This test verifies the chelation stability of trace elements by simulating a phosphorus-containing antagonistic environment.

[0109] The amino acid water-soluble fertilizer rich in trace elements prepared in Example 4 and the physical mixture prepared in Comparative Example 5 were extracted as test samples.

[0110] Accurately measure 10 mL of each sample and place them in two separate 100 mL volumetric flasks, then add deionized water to bring the volume to a final volume. Next, add 20 mL of a 0.5 mol / L dipotassium hydrogen phosphate (K₂HPO₄) solution to each sample to simulate a strong phosphate antagonistic environment. Adjust the pH of the mixture to 7.5 using a 1 mol / L sodium hydroxide solution (simulating a weakly alkaline fertilization environment), and stir at 200 rpm for 2 hours at 25°C.

[0111] After the reaction was completed, the solution was centrifuged at 10,000 r / min for 20 min to allow the generated inorganic salt precipitate to settle completely. The supernatant was extracted, filtered through a 0.22 μm microporous membrane, and the mass concentrations of available zinc and boron elements in the filtrate that remained in a soluble state were determined using inductively coupled plasma optical emission spectrometry (ICP-OES).

[0112] The initial soluble zinc and boron concentrations before the addition of dipotassium hydrogen phosphate interference were simultaneously determined, and the antiprecipitation retention rate was calculated (antiprecipitation retention rate = elemental concentration of supernatant after interference / elemental concentration of initial solution × 100%).

[0113] The test data is summarized in the table below.

[0114] Table 7. Results of Trace Element Anti-precipitation Retention Rate Determination under Simulated Antagonistic Environment

[0115] Figure 7 In the figure, the horizontal axis compares the initial state of the mixture with the state after adding dipotassium hydrogen phosphate and adjusting for alkali interference, while the vertical axis reflects the absolute concentration of effective trace elements that remain soluble after microporous filtration. The thick black line marked with a solid circle represents "Example 4," i.e., the water-soluble fertilizer rich in amino acid trace element polycyclic chelates prepared according to the method described in this invention. The black dashed line marked with a hollow square represents "Comparative Example 5," i.e., the mixture of free zinc and boron inorganic salts physically mixed only at room temperature.

[0116] As can be seen from Figures (a) and (b), the curve of Example 4 maintains a nearly flat extension after being subjected to strong antagonistic interference, exhibiting extremely high anti-precipitation retention rates (92.6% for zinc and 95.9% for boron), demonstrating the excellent stability of its amino acid trace element organic chelate structure. The trajectory segment of Comparative Example 5 shows a precipitous and rapid decline after interference, proving that free trace elements readily combine with phosphate and hydroxide ions in the environment to form insoluble precipitates, thus becoming ineffective.

[0117] According to the data in Table 7, Example 4 and Comparative Example 5 exhibit drastically different stability when faced with antagonistic interference from phosphate and a weakly alkaline environment. Comparative Example 5, being a simple physical mixture at room temperature, primarily contains zinc as free Zn. 2+ In its natural form, it reacts rapidly with dipotassium hydrogen phosphate to form an insoluble zinc phosphate precipitate, causing the zinc retention rate in its supernatant to plummet to 21.8%; free boron also suffers significant loss.

[0118] In contrast, the zinc retention rate in Example 4 was as high as 92.6%, and the boron retention rate reached 95.9%. This fully demonstrates that under the process conditions of Example 4 (dissolving under stirring in a buffer tank at a specific concentration and system), boric acid and zinc sulfate heptahydrate do not simply dissolve, but rather coordinate with the amino and carboxyl groups of the large number of free amino acids produced by secondary enzymatic hydrolysis, forming a polycyclic amino acid trace element chelate. This stable organic chelate structure retains Zn 2+ and B 3 + Encased internally, it effectively shields against attacks from external phosphate and hydroxide ions, thus maintaining extremely high water solubility and bioavailability in complex fertilization environments.

Claims

1. A water-soluble amino acid fertilizer, characterized in that, It contains the following ingredients by weight: 1000 portions of hydrolyzed amino acid stock solution of diseased and dead livestock and poultry protein with an initial pH of 1.0-1.5; 5-15 parts of crystal form regulator and dynamic protectant; The amount of alkaline neutralizing agent added is such that it can stabilize the pH value of the mixed system formed by mixing the hydrolyzed amino acid stock solution of diseased and dead livestock and poultry protein with the crystal form regulator and dynamic protectant to 4.0-6.

0. 1-5 parts of secondary hydrolysis complex enzyme.

2. The amino acid water-soluble fertilizer according to claim 1, characterized in that, The crystal form regulating and dynamic protective agent is composed of potassium polyaspartate powder with a weight average molecular weight of 2000-5000 and potassium lignosulfonate in a mass ratio of 1:1 to 1:

3.

3. The amino acid water-soluble fertilizer according to claim 1, characterized in that, The secondary hydrolysis complex enzyme is prepared by physically mixing animal protein hydrolytic endopeptidase and feather and hair hydrolytic exopeptidase in dry powder for 30 minutes. The ratio of enzyme activity units of animal protein hydrolytic endopeptidase and feather and hair hydrolytic exopeptidase is 2:1 to 3:

1. The total enzyme activity of the secondary hydrolytic complex enzyme is 70,000 U / g to 90,000 U / g.

4. The amino acid water-soluble fertilizer according to claim 1, characterized in that, The alkaline neutralizing agent is selected from calcium hydroxide powder, potassium hydroxide, or a suspension formed by premixing ammonia water and magnesium hydroxide. The raw material also includes 0 to 30 parts of excipients, which are composed of boric acid and zinc sulfate heptahydrate powder mixed in equal mass ratios.

5. A method for preparing an amino acid water-soluble fertilizer according to any one of claims 1-4, characterized in that, Includes the following steps: The hydrolyzed amino acid stock solution of the diseased and dead livestock and poultry protein was pumped into the reaction vessel, and the crystal form regulator and dynamic protectant was added under continuous stirring. The mixture was stirred evenly so that the crystal form regulator and dynamic protectant were evenly distributed in the strong acid system. While maintaining stirring, slowly add the alkaline neutralizing agent into the reactor to carry out the exothermic neutralization reaction. Stop adding alkali when the pH value of the system reaches 4.0-6.0, and then cool down and keep the temperature constant to obtain the liquid in the reactor. The secondary hydrolysis complex enzyme is added to the liquid in the reactor, and a secondary enzymatic hydrolysis reaction is carried out under constant temperature and stirring conditions to obtain the liquid. The liquid is heated to denature and inactivate the secondary hydrolysis complex enzyme. Then, primary pre-filtration is performed while it is still hot. The filtrate obtained from the primary pre-filtration is introduced into a microporous filtration system for pressure fine filtration. The homogeneous clear filtrate that has passed through the filtration membrane is collected to obtain the amino acid water-soluble fertilizer.

6. The method for preparing the amino acid water-soluble fertilizer according to claim 5, characterized in that, The continuous stirring and mixing temperature is 15-25℃, and the mixing time is 15-20 min; The operation of obtaining the liquid in the reactor by cooling and keeping it constant is as follows: the temperature of the liquid in the reactor after the neutralization and exothermic reaction is reduced to and kept constant at 30-50°C. The temperature of the secondary enzymatic hydrolysis reaction of the feed solution is kept constant at 30-50℃, and the hydrolysis time is 4.0-5.0 hours. The procedure for thermally denaturing and inactivating the secondary hydrolysis complex enzyme is as follows: raise the temperature of the reactor to 80-100°C and maintain it for 15-30 minutes.

7. The method for preparing the amino acid water-soluble fertilizer according to claim 5, characterized in that, The specific implementation methods of the primary pre-filtration and pressurized fine filtration are as follows: While still hot, the material solution after denaturation and inactivation of the compound enzyme is subjected to primary pre-filtration through a stainless steel mesh with a pore size of 30-50 mesh. The filtrate obtained from the primary pre-filtration is pumped into the buffer mixing tank. When the raw material contains excipients, the excipients are added to the primary filtrate in the buffer mixing tank. The mixture is stirred for 15 to 20 minutes until the excipients are completely dissolved, and then introduced into the microporous filtration system. The working fluid pressure is set to 0.3-0.5 MPa, allowing the liquid to pass through a 60-100 mesh microporous membrane assembly for pressurized fine filtration.

8. The method for preparing the amino acid water-soluble fertilizer according to claim 5, characterized in that, The crystal form regulating and dynamic protective agent uses raw materials including potassium polyaspartate, which is obtained through the following pre-preparation steps: L-Aspartic acid powder was placed in a vacuum reactor and subjected to thermal polycondensation at 180–220°C for 1.5–2.5 hours to generate the intermediate polysuccinimide. The intermediate polysuccinimide was suspended in deionized water, and a 10%–15% potassium hydroxide aqueous solution was slowly added dropwise at 60–70°C to carry out a ring-opening reaction. The pH of the system was maintained at 8.0–9.0, and the reaction was continued for 1–2 hours. Finally, the potassium aspartate powder was obtained by evaporation and drying.

9. The application of the amino acid water-soluble fertilizer according to any one of claims 1-4 in foliar spraying or drip irrigation fertilization with high-hardness water.

10. The application according to claim 9, characterized in that, The application includes the following specific application methods: After diluting and mixing the amino acid water-soluble fertilizer with water, spray it evenly onto the plant leaves. Alternatively, the amino acid water-soluble fertilizer can be injected into a drip irrigation system with high-hardness water and applied with the drip irrigation water.

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