Preparation process and application of a new rooting long-acting biological stimulant

Abstract

The present application relates to the technical field of fertilizer production, and particularly relates to a preparation process of a novel rooting long-acting biological stimulant and application thereof, which comprises raw material pretreatment, three-stage gradient enzymolysis and multi-stage gradient membrane separation and concentration steps, the three-stage gradient enzymolysis is carried out in a gradient temperature control reaction kettle, the reaction kettle is provided with three-stage independent temperature control jackets and a double-layer paddle mixing flow guide assembly with a flow guide cylinder, so that an axial circulation flow field is formed in the kettle, the axial temperature difference is controlled within ±0.5 DEG C, and local overheating inactivation of the enzyme preparation is avoided. The membrane separation adopts a three-stage gradient system of microfiltration-ultrafiltration-nanofiltration in series, the target active oligosaccharide is enriched by grading interception, and the purity of the effective component is high. The obtained biological stimulant can be sprayed on the surface of compound fertilizer particles as a coating functional liquid, and has the functions of rooting, growth promotion and nutrient slow release. The preparation process of the biological stimulant has sufficient enzymolysis, high separation precision, stable product activity, and is suitable for large-scale production of agricultural biological stimulants.

Description

Technical Field

[0001] This invention relates to the field of fertilizer production technology, specifically to a preparation process and application of a novel long-acting rooting biostimulant. Background Technology

[0002] Biostimulants, as active substances that promote plant growth, enhance stress resistance, and improve nutrient utilization, have become an important component of modern agricultural inputs. Among them, root-promoting biostimulants have significant application value in crop transplanting, seedling management, and soil remediation. Currently, the industry mainly uses seaweed, humic acid, and soybean meal as raw materials, employing an enzymatic hydrolysis-membrane separation-compounding process. These biostimulants are then coated onto the surface of compound fertilizer granules to achieve a synergistic release of nutrient supply and root-promoting stimulation.

[0003] Chinese invention patent application CN106278601A discloses a method for preparing a biostimulant-containing humic acid water-soluble fertilizer. The process includes four steps: preparing a rooting composition, preparing a biostimulant with rooting effects, preparing raw materials for the humic acid-containing water-soluble fertilizer, and final mixing. This method uses a conventional stirring vessel for mixing and reaction, achieving the compounding of biostimulant and humic acid water-soluble fertilizer through simple mass proportioning. However, in practical application, this technical solution has the following shortcomings: First, the enzymatic hydrolysis process uses a jacketed, centrally heated reactor with heating elements concentrated on the outer wall of the reactor. The temperature difference between the top and bottom of the reactor can reach 3-5°C, leading to localized overheating and varying degrees of thermal inactivation of enzymes such as cellulase and pectinase, resulting in decreased enzymatic hydrolysis efficiency and a dispersed oligosaccharide polymerization degree distribution. Second, the separation and purification process only uses simple filtration to remove large particulate impurities, lacking the ability to grade and retain impurities. The product contains a high content of byproducts such as impurities and large-molecule polysaccharides, while the proportion of active oligosaccharides and other effective components is relatively low, resulting in inconsistent rooting activity and poor batch stability.

[0004] Furthermore, existing membrane separation equipment generally suffers from insufficient fractionation accuracy and rapid membrane fouling rates. Conventional single-stage ultrafiltration membranes have limited rejection resolution for components with similar molecular weights, making it difficult to accurately separate target active oligosaccharides from impurities. At the same time, colloidal substances in the enzymatic hydrolysate easily form a gel layer on the membrane surface, and the flux decreases significantly after several hours of operation, requiring frequent chemical cleaning, which further exacerbates the quality fluctuations between product batches.

[0005] In summary, the existing technologies for preparing biostimulants mainly suffer from technical problems such as poor uniformity of enzymatic hydrolysis reaction temperature leading to significant enzyme activity loss and low separation and purification precision resulting in insufficient purity of active ingredients. These problems restrict the further improvement of the activity retention rate of biostimulants and the rooting effect of the products. Summary of the Invention

[0006] This invention provides a novel preparation process and application of a rooting and long-acting biostimulant, which solves the technical problems in the preparation of biostimulants in the prior art, such as poor temperature uniformity leading to enzyme activity loss and low separation and purification precision leading to insufficient purity of effective components.

[0007] To address the above problems, the preparation process of the novel rooting long-acting biostimulant provided by this invention adopts the following technical solution: A novel rooting and long-acting biostimulant preparation process includes the following steps: S1, raw material pretreatment: seaweed and soybean meal are mixed in a certain proportion, water is added to make a slurry, and high-temperature sterilization is performed; S2, gradient enzymatic hydrolysis: the sterilized slurry is sent into a gradient temperature-controlled reactor and enzymatic hydrolysis is performed in three stages in sequence, with the temperature of the three stages decreasing step by step, and the holding time of each stage is independently controlled; S3, membrane separation and concentration: the enzymatic hydrolysate is subjected to multi-stage gradient membrane separation and concentration to retain the target active ingredient, remove macromolecular impurities and small molecule salts, and obtain the rooting and long-acting biostimulant.

[0008] Its beneficial effects are as follows: by segmented temperature-controlled enzymatic hydrolysis to adapt to the optimal reaction conditions of different enzyme preparations, and combined with multi-stage membrane fractionation retention, impurities can be gradually removed and target active ingredients can be enriched on the basis of sufficient enzymatic hydrolysis, thereby improving the purity and activity of the effective components in the biostimulant as a whole, and the product quality stability is high.

[0009] Furthermore, in step S1, the mass ratio of seaweed to soybean meal is 1:0.3-0.8, and the solid content of the slurry is 15%-25%; the high-temperature sterilization temperature is 80-90℃, and the sterilization time is 15-30 minutes.

[0010] Furthermore, the three-stage gradient enzymatic hydrolysis in step S2 is as follows: the first stage is at a temperature of 50-55℃, incubated for 30-60 minutes, and a complex enzyme system of cellulase and pectinase is added; the second stage is at a temperature of 45-50℃, incubated for 60-90 minutes, and a protease is added; the third stage is at a temperature of 35-42℃, incubated for 90-120 minutes, and alginate lyase is added.

[0011] Its beneficial effects are as follows: by adding different enzyme systems in sequence from high to low temperature, the cellulase and pectinase under the first high temperature condition preferentially break down the seaweed cell wall and release the effective substances inside the cell. Under the second medium temperature condition, the protease decomposes soybean meal protein to generate small molecule active peptides. Under the third low temperature condition, alginate lyase directionally degrades seaweed polysaccharides to generate functional oligosaccharides. The step-cooling sequence matches the optimal temperature of each enzyme, and the activity of all kinds of enzymes is protected, which can improve the enzymatic hydrolysis efficiency.

[0012] Furthermore, in step 3, the multi-stage gradient membrane separation and concentration adopts a three-stage tandem gradient membrane separation and concentration system, which sequentially includes a primary microfiltration unit, a secondary ultrafiltration unit, and a tertiary nanofiltration unit. The primary microfiltration unit uses a 0.1-micron ceramic microfiltration membrane and operates at a pressure of 0.2-0.3 MPa; the secondary ultrafiltration unit uses a polyethersulfone ultrafiltration membrane with a molecular weight cutoff of 10 kDa and operates at a pressure of 0.5-0.8 MPa; and the tertiary nanofiltration unit uses a nanofiltration membrane with a molecular weight cutoff of 500 Da and operates at a pressure of 1.2-1.5 MPa.

[0013] Its beneficial effects are as follows: primary microfiltration removes suspended residues and bacteria from the feed liquid, secondary ultrafiltration retains large molecular weight proteins and undegraded polysaccharides, and tertiary nanofiltration enriches active oligosaccharides of the target molecular weight and removes small molecule salts, thereby improving separation accuracy and ensuring the purity of the target active ingredients.

[0014] Furthermore, the gradient temperature-controlled reactor includes a reactor body, a reactor cover, and a heat exchange jacket; the heat exchange jacket includes an upper jacket and a lower jacket, and the lower jacket is provided with an annular partition to divide it into an upper chamber and a lower chamber. The upper jacket, the upper chamber of the lower jacket, and the lower chamber of the lower jacket are respectively provided with independent heat transfer oil inlets and outlets, forming three independent temperature control circuits.

[0015] Its beneficial effects are as follows: by adopting a dual-chamber partition structure with an upper jacket and a lower jacket, and further dividing the lower jacket into upper and lower chambers by an annular partition, three independent temperature control circuits are formed, which can accurately control the heat exchange temperature of the upper, middle and lower parts of the reactor body, avoid the lag of repeated heating and cooling of the reactor, and make the temperature regulation response faster and the enzymatic hydrolysis temperature of each stage in the reactor more accurate.

[0016] Furthermore, the gradient temperature-controlled reactor also includes a mixing and guiding assembly, which includes a stirring shaft, a drive motor, a guide tube, an ascending vane assembly, and a descending vane assembly. The guide tube is coaxially disposed inside the reactor body, the ascending vane assembly is fixed to the stirring shaft and located inside the guide tube, and is used to drive the material inside the tube to flow upward. The descending vane assembly is fixedly connected to the stirring shaft and located outside the guide tube, and is used to drive the material in the annular region outside the tube to flow downward, so as to form an axial circulating flow field.

[0017] Its beneficial effects are as follows: the flow guide tube divides the space inside the vessel into two flow channels, one inside and one outside the tube. With the synergistic effect of the inner rising blades and the outer falling blades, the material flows upward along the inside of the flow guide tube and downward along the annular space outside the tube, forming a stable axial circulating flow field. This flow field can break up the temperature stratification inside the vessel, reduce the axial temperature difference, make the temperature of the material in all parts of the vessel tend to be uniform, and reduce the enzyme inactivation caused by local overheating.

[0018] Furthermore, the descending blade assembly includes a support ring and multiple descending blades. The support ring is coaxially fixed to the outer edge of the lowest ascending blade. Multiple sets of vertically opposed blade clamps are evenly distributed on the outer wall of the support ring. The descending blades are detachably clamped and fixed between the blade clamps by bolts. The guide tube is composed of an upper guide tube and a lower guide tube coaxially connected, with the same inner diameter. The upper guide tube is fixed to the inner wall of the vessel lid by circumferentially distributed upper supports, and the lower guide tube is fixed to the inner wall of the vessel by at least two sets of axially spaced support groups.

[0019] Furthermore, the outer side of the vessel body and the lower jacket is covered with an outer protective layer, and an air insulation jacket is formed between the outer protective layer and the lower jacket; multiple fixed supports are evenly distributed around the outer wall of the outer protective layer for supporting the installation of the reactor.

[0020] Furthermore, the gradient temperature-controlled reactor also includes a temperature detection device, which comprises three sets of temperature detection components, corresponding to the axial positions of the upper jacket, the upper cavity of the lower jacket, and the lower cavity of the lower jacket, respectively. Each set of temperature detection components includes three temperature sensors, with the sensing ends extending into the inside of the guide tube, the annular area between the guide tube and the reactor wall, and the inner wall side of the reactor, respectively, and connected to the independent temperature control circuit of the corresponding jacket chamber.

[0021] An application of a novel rooting and long-acting biostimulant involves spraying the aforementioned biostimulant as a coating functional liquid onto the surface of compound fertilizer granules, with the amount added being 1.5%-3.5% of the mass of the compound fertilizer granules. Attached Figure Description

[0022] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the invention are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein: Figure 1 This is a schematic diagram of the overall structure of a gradient temperature controlled reactor; Figure 2 for Figure 1 The image shows a front view of a gradient temperature controlled reactor. Figure 3 for Figure 1 The top view of the gradient temperature controlled reactor shown; Figure 4 for Figure 3 Sectional view at point A in the middle; Figure 5 for Figure 4 A magnified view of a portion of point E in the middle; Figure 6 for Figure 3 Sectional view at point B; Figure 7 for Figure 3 Sectional view at point C; Figure 8 for Figure 7 Enlarged view of part D in the middle Figure 9 This is a schematic diagram of the stirring shaft. Figure 10 for Figure 9 A magnified view of a portion of point F in the middle.

[0023] Explanation of reference numerals in the attached figures: 1. Kettle body; 11. Discharge port; 12. Discharge valve; 2. Kettle cover; 21. Motor mounting base; 22. Exhaust port; 23. Feed port; 3. Zoned heat exchange jacket; 31. Upper jacket; 32. Lower jacket; 33. Annular baffle; 34. Oil inlet; 35. Oil outlet; 4. Outer protective layer; 41. Fixing base; 42. Pressure gauge; 5. Mixing and guiding assembly; 51. Stirring motor; 52. Motor fixing cylinder; 53. Stirring shaft; 531. Bearing; 532. Mechanical seal; 54. Guide cylinder; 541. Upper guide cylinder; 542. Lower guide cylinder; 543. Upper support; 544. Lower support; 55. Upflow blade assembly; 551. Upflow blade; 56. Support ring; 561. Blade clamp; 57. Downflow blade; 6. Temperature detection device; 61. Temperature sensor. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Those skilled in the art should understand that the embodiments described below are only some, not all, of the embodiments disclosed. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] The principles and spirit of the present invention will be explained in detail below with reference to several representative embodiments.

[0026] Examples of the preparation process of the long-acting biostimulant provided by this invention: A novel long-acting rooting biostimulant preparation process is described below: S1. First, the raw materials are pretreated. Fresh kelp and low-temperature defatted soybean meal are weighed at a mass ratio of 1:0.5, crushed, and added to a mixing tank. Deionized water is added to make a slurry with a solid content of 20%. The slurry is then heated to 85°C for high-temperature sterilization, kept at that temperature for 20 minutes, and then cooled to below 55°C to complete the pretreatment process. The pretreated slurry is then fed into the gradient enzymatic hydrolysis reactor through the feed pump at inlet 23, ready for the gradient enzymatic hydrolysis reaction.

[0027] S2. Then, a three-stage gradient enzymatic hydrolysis is performed. First stage: The jacketed heat transfer oil circulation loop of the gradient enzymatic hydrolysis reactor is simultaneously activated to raise the overall temperature of the liquid inside the reactor and stabilize it at 52℃. A complex enzyme system of cellulase and pectinase is added at 0.2% of the slurry mass (mass ratio 2:1). Stirring is started to initiate the enzymatic hydrolysis reaction, and the temperature is maintained for 45 minutes. Second stage: The overall temperature inside the reactor is lowered to 48℃, and neutral protease is added at 0.15% of the slurry mass. Enzymatic hydrolysis continues for 75 minutes. Third stage: The overall temperature inside the reactor is further lowered to 38℃, and alginate lyase is added at 0.1% of the slurry mass. The reaction is maintained for 105 minutes. After enzymatic hydrolysis, the bottom discharge valve 12 is opened, and the liquid is discharged to enter the subsequent membrane separation process.

[0028] By adding different enzyme systems sequentially from high to low temperature, the cellulase and pectinase under the first high-temperature condition can preferentially break down the seaweed cell wall and release intracellular effective substances. Under the second medium temperature condition, the protease decomposes soybean meal protein to generate small molecule active peptides. Under the third low temperature condition, alginate lyase directionally degrades seaweed polysaccharides to generate functional oligosaccharides. The stepwise cooling sequence matches the optimal temperature of each enzyme, and the activities of all enzymes can be protected, thereby improving the enzymatic hydrolysis efficiency.

[0029] The gradient temperature-controlled reactor consists of a reactor body 1, a reactor lid 2, a zoned heat exchange jacket 3, an outer protective layer 4, a mixing and flow guiding assembly 5, and a temperature detection device 6, providing a uniform temperature field and a sufficient mixing environment for gradient enzymatic hydrolysis. The reactor lid 2 and reactor body 1 are connected in a sealed manner via a flange structure and a sealing gasket. The top of the reactor lid 2 is equipped with a motor mounting base 21, a feed inlet 23, and an exhaust port 22. The exhaust port 22 is equipped with an exhaust valve (not shown in the figure) to replace air inside the reactor, discharge water vapor and gaseous reactants generated during the heating process, and balance the gas phase pressure inside the reactor body 1. The bottom of the reactor body 1 is equipped with a discharge port 11, which is fitted with a discharge valve 12 to control the discharge of the enzymatically hydrolyzed product.

[0030] The partitioned heat exchange jacket 3 adopts a three-section independent chamber structure, including an upper jacket 31 and a lower jacket 32. The upper jacket 31 circumferentially covers the outer periphery of the vessel cover 2, and the lower jacket 32 ​​circumferentially covers the outer periphery of the vessel body 1. An annular partition 33 is provided in the cavity formed between the lower jacket 32 ​​and the vessel body 1, dividing the cavity of the lower jacket 32 ​​into an independent upper and lower cavity. The upper jacket 31, the upper cavity of the lower jacket 32, and the lower cavity of the lower jacket 32 ​​are respectively provided with independent heat transfer oil inlets 34 and outlets 35, each connected to a heat transfer oil circulation unit, forming three independent temperature control loops. The three loops work synchronously, respectively providing heat exchange compensation for the vessel cover 2, the upper part of the vessel body 1, and the lower part of the vessel body 1, eliminating the axial temperature difference of traditional jackets where the lower part is hot and the upper part is cold, and ensuring uniform material temperature throughout the vessel.

[0031] By adopting a dual-chamber partition structure with an upper jacket 31 and a lower jacket 32, and further dividing the lower jacket 32 ​​into upper and lower chambers by an annular partition 33, three independent temperature control loops are formed. The heat exchange temperature of the upper, middle and lower parts of the reactor body 1 can be precisely controlled separately, avoiding the lag of repeated heating and cooling of the reactor, resulting in faster temperature regulation response and more precise enzymatic hydrolysis temperature at each stage inside the reactor.

[0032] The outer periphery and bottom of the vessel body 1 are also covered by an outer protective layer 4, which is located outside the lower jacket 32. An air gap is left between the outer protective layer 4 and the lower jacket 32 ​​to provide insulation and protection. Multiple fixing seats 41 are evenly distributed around the outer wall of the outer protective layer 4 for fixing and supporting the entire reactor. A pressure gauge 42 connected to the inner cavity of the vessel body 1 is also provided on the side wall of the outer protective layer 4 to display the internal pressure of the vessel body 1 in real time.

[0033] The mixing and guiding assembly 5 includes a stirring motor 51, a motor mounting cylinder 52, a stirring shaft 53, a guide cylinder 54, an upflow blade assembly 55, a support ring 56, and downflow blades 57. The stirring motor 51 is mounted on a motor mounting base 21 of the vessel cover 2. The motor mounting base 21 is fixed to the motor mounting cylinder 52 via a flange. The stirring motor 51 is fixedly mounted on the top of the motor mounting cylinder 52, with its output end facing downwards. The stirring shaft 53 is fixedly mounted on the output end of the stirring motor 51 and extends vertically. The lower end of the stirring shaft 53 passes through the motor mounting cylinder 52 and extends into the interior of the reactor. A bearing 531 is fitted inside the motor mounting cylinder 52 and sleeved on the stirring shaft 53. A sealing element is installed between the motor mounting base 21 and the stirring shaft 53. In this embodiment, the sealing element is a mechanical seal 532 to ensure a sealing effect between the stirring shaft 53 and the vessel cover 2. Four sets of rising blades 55 are arranged at equal intervals along the vertical direction on the stirring shaft 53. Each set of rising blades 55 includes six rising blades 551 that are evenly distributed circumferentially and arranged obliquely on the outer periphery of the stirring shaft 53. The rising blades 551 rotate under the drive of the stirring motor 51, which can drive the material in the reactor to form a continuous upward flow.

[0034] The guide tube 54 is a cylindrical body, comprising an upper guide tube 541 and a lower guide tube 542 connected vertically and having the same inner diameter. The upper guide tube 541 is coaxially fixed inside the vessel lid 2, and has three upper supports 543 evenly arranged circumferentially. The two ends of the upper supports 543 are respectively fixedly connected to the outer wall of the upper guide tube 541 and the inner wall of the vessel lid 2 to achieve fixation between the upper guide tube 541 and the vessel lid 2. The lower guide tube 542 is coaxially fixed inside the vessel body 1, and has two support groups arranged vertically. Each support group includes three lower supports 544 evenly distributed circumferentially on the outside of the lower guide tube 542. The two ends of the lower supports 544 are respectively fixedly connected to the outer wall of the lower guide tube 542 and the inner wall of the vessel body 1 to achieve fixation between the lower guide tube and the vessel body.

[0035] The diameter of the rising blade 551 is smaller than the inner diameter of the guide tube 54. The guide tube 54 is sleeved on the outside of each rising blade assembly 55 to guide the material flow to circulate inside and outside the guide tube 54. The rising blade assembly 55 at the bottom is located below the guide tube 54, and a support ring 56 is fixed to its outer circumference. The support ring 56 is an annular plate extending vertically. The inner wall of the support ring 56 is fixedly connected to the outer edge of each rising blade 551 of the bottom blade assembly. Multiple descending blades 57 are evenly distributed and inclined on the outer wall of the support ring 56. Each descending blade 57 is detachably assembled on the support ring 56. Specifically, multiple clamping plate assemblies are evenly distributed on the outer wall of the support ring 56. Each clamping plate assembly includes two blade clamping plates 561 arranged vertically at intervals. The descending blades 57 are fixed between the two blade clamping plates 561 by bolts. The descending blades 57 are used to drive the material flow between the outer wall of the guide tube 54 and the inner wall of the reactor downwards, accelerating the material flow circulation inside and outside the guide tube 54. Additionally, the upper end of the upper guide tube 541 has a radially outward-curved arc-shaped upper edge, and the lower end of the lower guide tube 542 has a radially inward-curved arc-shaped lower edge to reduce the circulation resistance of the material flow. It should be noted that the maximum diameter of the blade clamp 561 from the rotation center is smaller than the minimum inner diameter of the guide tube 54, so that the stirring shaft 53 and the support ring 56 can pass through the guide tube 54 for assembly and fixation.

[0036] The flow guide tube 54 divides the internal space of the vessel into two flow channels: an inner channel and an outer channel. With the synergistic effect of the inner rising vane 551 and the outer falling vane 57, the material flows upward along the inside of the flow guide tube 54 and downward along the annular space outside the tube, forming a stable axial circulating flow field. This flow field can break up the temperature stratification inside the vessel, reduce the axial temperature difference, make the temperature of the material in all parts of the vessel tend to be uniform, and reduce the enzyme inactivation caused by local overheating.

[0037] The temperature detection device 6 includes three sets of temperature detection components arranged sequentially from top to bottom. The uppermost temperature detection component is fixed to the outside of the upper jacket 31, the middle temperature detection component is fixed to the upper end of the outer protective layer 4, and the lower temperature detection component is fixed to the lower end of the outer protective layer 4. Each set of temperature detection components includes three temperature sensors 61. The sensing ends of the three temperature sensors 61 extend into the inside of the guide tube 54, the cavity between the guide tube 54 and the inner wall of the reactor, and the side of the inner wall of the reactor, respectively, to comprehensively detect the temperature of the material flow at various points in the reactor. The average value of the detection data of the three sensors in each set is fed back to the PID temperature control unit of the corresponding section of the jacket to assist the three sets of jacket circuits in coordinated adjustment to ensure that the axial temperature difference of the entire reactor is within a controllable range.

[0038] S3. After enzymatic hydrolysis, the feed solution is sent to a three-stage tandem gradient membrane separation and concentration system for purification and concentration. The feed solution first enters the primary microfiltration unit using a 0.1-micron ceramic microfiltration membrane, with the operating pressure controlled at 0.25 MPa. This removes suspended solids such as bacterial residues and undegraded fiber particles. The permeate then enters the secondary ultrafiltration unit. The secondary ultrafiltration unit uses a polyethersulfone ultrafiltration membrane with a molecular weight cutoff of 10 kDa, operating at 0.6 MPa, to remove large molecular weight proteins, polysaccharides, and other impurities. The permeate continues to the tertiary nanofiltration unit. The tertiary nanofiltration unit uses a nanofiltration membrane with a molecular weight cutoff of 500 Da, operating at 1.3 MPa, to remove the target active oligosaccharides and small molecule salts. Finally, the solution is concentrated to a solid content of approximately 30% to obtain the final product.

[0039] The application of a novel root-promoting and long-acting biostimulant involves using compound fertilizer granules with a total nitrogen, phosphorus, and potassium content of 45% as the substrate. The biostimulant prepared in the above-mentioned example is diluted to a solid content of 15% as a coating solution. A rotary drum coating process is employed, with the amount added being 2.5% of the compound fertilizer granule mass. During the coating process, the granules roll within the drum, allowing the biostimulant to be evenly coated onto the granule surface. After hot air drying, a continuous functional film layer is formed. The coated compound fertilizer granules have a smooth surface, are less prone to clumping, and the nutrient release period is extended from the conventional 30 days to 75 days. It also possesses the dual functions of promoting root growth and improving fertilizer efficiency, making it suitable for basal fertilizer application to field crops and cash crops.

[0040] Based on the above description in this specification, those skilled in the art will also understand that the following terms used, such as "upper," "lower," "front," "rear," "left," "right," "width," "horizontal," "top," "bottom," "inner," and "outer," which indicate orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings of this specification. They are only for the purpose of facilitating the explanation of the present invention and simplifying the description, and do not explicitly or implicitly suggest that the device or element involved must have the specific orientation, or be constructed and operated in a specific orientation. Therefore, the above-mentioned orientation or positional relationship terms should not be understood or interpreted as limitations on the present invention.

[0041] In addition, in the description of this specification, "multiple" means at least two, such as two, three or more, etc., unless otherwise expressly and specifically defined.

Claims

1. A preparation process for a novel long-acting rooting biostimulant, characterized in that, Includes the following steps: S1. Raw material pretreatment: Mix seaweed and soybean meal in a certain proportion, add water to make a slurry, and then sterilize it at high temperature. S2. Gradient enzymatic hydrolysis: The sterilized slurry is fed into a gradient temperature controlled reactor and enzymatic hydrolysis is carried out in three stages in sequence. The temperature of the three stages of enzymatic hydrolysis is gradually reduced, and the holding time of each stage is independently controlled. S3. Membrane separation and concentration: The enzymatic hydrolysate is subjected to multi-stage gradient membrane separation and concentration to retain the target active ingredients, remove macromolecular impurities and small molecule salts, and obtain a rooting long-acting biostimulant.

2. The preparation process of the long-acting biostimulant according to claim 1, characterized in that, In step S1, the mass ratio of seaweed to soybean meal is 1:0.3-0.8, and the solid content of the slurry is 15%-25%; the high-temperature sterilization temperature is 80-90℃, and the sterilization time is 15-30 minutes.

3. The preparation process of the novel long-acting rooting biostimulant according to claim 1, characterized in that, The three-stage gradient enzymatic hydrolysis in step S2 is as follows: the first stage is at a temperature of 50-55℃, incubated for 30-60 minutes, and a complex enzyme system of cellulase and pectinase is added; the second stage is at a temperature of 45-50℃, incubated for 60-90 minutes, and a protease is added; the third stage is at a temperature of 35-42℃, incubated for 90-120 minutes, and alginate lyase is added.

4. The preparation process of the novel long-acting rooting biostimulant according to claim 1, characterized in that, In step 3, the multi-stage gradient membrane separation and concentration adopts a three-stage tandem gradient membrane separation and concentration system, which includes a primary microfiltration unit, a secondary ultrafiltration unit, and a tertiary nanofiltration unit. The primary microfiltration unit uses a 0.1-micron ceramic microfiltration membrane and operates at a pressure of 0.2-0.3 MPa; the secondary ultrafiltration unit uses a polyethersulfone ultrafiltration membrane with a molecular weight cutoff of 10 kDa and operates at a pressure of 0.5-0.8 MPa; and the tertiary nanofiltration unit uses a nanofiltration membrane with a molecular weight cutoff of 500 Da and operates at a pressure of 1.2-1.5 MPa.

5. The preparation process of the novel long-acting rooting biostimulant according to claim 1, characterized in that, The gradient temperature-controlled reactor includes a reactor body, a reactor cover, and a heat exchange jacket. The heat exchange jacket includes an upper jacket and a lower jacket. The lower jacket is provided with an annular partition that divides it into an upper chamber and a lower chamber. The upper jacket, the upper chamber of the lower jacket, and the lower chamber of the lower jacket are each provided with an independent heat transfer oil inlet and outlet, forming three independent temperature control circuits.

6. The preparation process of the novel long-acting rooting biostimulant according to claim 5, characterized in that, The gradient temperature controlled reactor also includes a mixing and guiding assembly, which includes a stirring shaft, a drive motor, a guide tube, an ascending vane assembly, and a descending vane assembly. The guide tube is coaxially disposed inside the reactor body, and the ascending vane assembly is fixed to the stirring shaft and located inside the guide tube, used to drive the material inside the tube to flow upward. The descending blade assembly is fixedly connected to the stirring shaft and located outside the guide tube. It is used to drive the material in the annular area outside the tube to flow downwards, so as to form an axial circulating flow field.

7. The preparation process of the novel long-acting rooting biostimulant according to claim 6, characterized in that, The descending blade assembly includes a support ring and multiple descending blades. The support ring is coaxially fixed to the outer edge of the lowest ascending blade. Multiple sets of vertically opposed blade clamps are evenly distributed on the outer wall of the support ring. The descending blades are detachably clamped and fixed between the blade clamps by bolts. The guide tube is composed of an upper guide tube and a lower guide tube coaxially connected, with the same inner diameter. The upper guide tube is fixed to the inner wall of the vessel lid by circumferentially distributed upper supports, and the lower guide tube is fixed to the inner wall of the vessel by at least two sets of axially spaced support groups.

8. The preparation process of the novel long-acting rooting biostimulant according to claim 5, characterized in that, The outer side of the vessel body and the lower jacket is covered with an outer protective layer, and an air insulation interlayer is formed between the outer protective layer and the lower jacket; multiple fixed supports are evenly distributed around the outer wall of the outer protective layer for the installation and support of the reactor.

9. The preparation process of the novel long-acting rooting biostimulant according to claim 5, characterized in that, The gradient temperature-controlled reactor also includes a temperature detection device, which comprises three sets of temperature detection components, corresponding to the axial positions of the upper jacket, the upper cavity of the lower jacket, and the lower cavity of the lower jacket, respectively. Each set of temperature detection components includes three temperature sensors, with the sensing ends extending into the inside of the guide tube, the annular area between the guide tube and the reactor wall, and the inner wall side of the reactor, respectively, and connected to the independent temperature control circuit of the corresponding jacket chamber.

10. The application of a novel long-acting rooting biostimulant, characterized in that, The biostimulant described in any one of claims 1-9 is sprayed onto the surface of compound fertilizer granules as a coating functional liquid, and the amount added is 1.5%-3.5% of the mass of the compound fertilizer granules.

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