Bacterial membrane in-situ modified leaf fertilizer and preparation method thereof

Abstract

The invention relates to the technical field of fertilizers, and discloses a bacterial membrane in-situ modified foliar fertilizer and a preparation method thereof, and the method comprises the following steps: preparing a biological activity initial system; adding a manganese ion source, an iron ion source and a molybdenum ion source into the bioactive initial system to obtain a metal ion mixed system, and performing ultrasonic cavitation and stirring treatment to obtain a modified fertilizer solution with a nano-particle layer loaded on the surface of a bacterial membrane; adding the modified fertilizer solution into the slow-release carrier solution, stirring, and freeze-drying to obtain a coated modified compound fertilizer; sequentially adding the coated modified compound fertilizer and the inorganic support phase into the gel-forming matrix solution, adding the obtained multiphase composite sol into the cross-linking solution to form a gel microsphere precursor, and performing post-treatment to obtain the foliar fertilizer. By introducing the ultrasonic cavitation effect, the problem of insufficient interaction between a bacterial membrane and fertilizer ions in the traditional compound fertilizer preparation process is solved, so that the bacterial activity, the fertilizer slow release performance and the crop nutrient absorption efficiency are improved.

Description

Technical Field

[0001] This invention belongs to the field of fertilizer technology, specifically relating to a bacterial membrane in-situ modified foliar fertilizer and its preparation method. Background Technology

[0002] Existing enzyme-containing foliar fertilizers typically employ mechanical mixing and dispersion methods to integrate nitrogen, phosphorus, and potassium fertilizers with compound bacterial powder. In the fertilizer solution, the effect of the bacterial membrane surface on fertilizer ions depends on surface adsorption, ion exchange, and coating mechanisms. However, conventional stirring makes it difficult to achieve uniform dispersion at the nanoscale, leading to bacterial aggregation or membrane structure damage. This results in decreased bacterial and enzyme activity, thereby affecting their colonization effect on crop leaves.

[0003] Furthermore, insufficient binding of fertilizer ions on the bacterial membrane surface leads to uneven nutrient release, resulting in unstable nutrient supply to crops during the grain-filling stage and limited yield improvement. Although existing technologies introduce ultrasonic dispersion in the subsequent compound sol stage, this process only serves a physical dispersion function and lacks optimization for the early interaction between bacteria and fertilizer, thus limiting overall fertilizer efficiency.

[0004] Meanwhile, with the increasing soil salinization and climate change, existing foliar fertilizers still suffer from problems such as low nutrient utilization efficiency and insufficient crop resistance in long-term application. Therefore, how to enhance the interaction between bacterial membranes and fertilizer ions while maintaining bacterial activity, thereby achieving stable and slow release of nutrients and improving fertilizer efficiency, has become a pressing technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a bacterial membrane in-situ modified foliar fertilizer and its preparation method. By introducing ultrasonic cavitation, the problem of insufficient ion interaction between bacterial membrane and fertilizer in the traditional compound fertilizer preparation process is solved, thereby improving bacterial activity, fertilizer slow-release performance and crop nutrient absorption efficiency.

[0006] This invention provides the following technical solution: In a first aspect, a method for preparing a bacterial membrane-modified foliar fertilizer is provided, comprising the following steps: The compound bacterial powder and compound enzyme preparation were premixed, and then nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer were added to obtain a mixture. An aqueous solution of surfactant was added to the mixture, and after stirring evenly, the pH was adjusted to obtain the initial biologically active system. Manganese ion source, iron ion source and molybdenum ion source were added to the initial bioactive system and stirred evenly to obtain a mixed metal ion system. A modified fertilizer solution with a nanoparticle layer loaded on the surface of a bacterial membrane was obtained by ultrasonic cavitation and stirring of a metal ion mixture system. The modified fertilizer solution was added to the slow-release carrier solution, stirred evenly, and then freeze-dried to obtain a coated modified compound fertilizer with a slow-release interface. Layered inorganic minerals were dispersed in an aqueous solution and stirred to expand. Then, surface modifiers and complexing stabilizers were added. After the reaction, the mixture was filtered, washed, and dried to obtain an inorganic supported phase. A coated modified compound fertilizer and an inorganic support phase were sequentially added to a gelling matrix solution, and ultrasonic treatment was performed to obtain a multiphase composite sol. The multiphase composite sol was then added dropwise to a crosslinking solution to form a gel microsphere precursor. After post-treatment, an in-situ modified foliar fertilizer with bacterial membrane was obtained.

[0007] Furthermore, the mass fractions of each component in the mixture are as follows: 5-10 parts of compound bacterial powder, 3-8 parts of compound enzyme preparation, 30-40 parts of nitrogen fertilizer, 20-30 parts of phosphate fertilizer, and 20-30 parts of potassium fertilizer. And / or, the mass fraction of the mixture in the surfactant aqueous solution is 20-30 wt%; And / or, the mixture is stirred evenly in an aqueous surfactant solution and the pH is adjusted to 6.5-7.5.

[0008] In the above technical solution, the addition of compound bacterial powder and compound enzyme preparation is beneficial to improving the biological activity and stability of the system, and provides the basic conditions for the modification of bacterial membrane surface during subsequent ultrasonic cavitation treatment.

[0009] Furthermore, the manganese ion source is manganese sulfate, the iron ion source is ferric chloride, and the molybdenum ion source is sodium molybdate; And / or, after adding manganese ion source, iron ion source and molybdenum ion source to the initial bioactive system, stir at room temperature for 5-10 minutes to ensure that the metal ions are uniformly dispersed in the initial bioactive system.

[0010] Furthermore, in the initial bioactive system, the final concentration of manganese ions is 0.1~0.5 mmol / L, the final concentration of iron ions is 0.2~0.6 mmol / L, and the final concentration of molybdenum ions is 0.05~0.2 mmol / L.

[0011] Furthermore, methods for ultrasonic cavitation and stirring of metal ion mixtures include: The metal ion mixture system was subjected to ultrasonic treatment in an ultrasonic bath or probe-type ultrasonic instrument at a frequency of 20-40 kHz, a power of 50-100 W, and a treatment time of 10-30 min. An intermittent ultrasonic mode was used: a 1-min pause was taken after every 5 min of ultrasonic treatment. The reaction temperature was controlled at 25-40℃, and stirring was maintained at a speed of 200-300 rpm. After the ultrasonic treatment was completed, stirring was continued for 10-15 min.

[0012] In the above technical solution, under the action of ultrasonic cavitation, Mn 2+ Oxidation produces MnO2 nanoparticles, Fe 3+ Reduction to produce Fe3O4, Mo 6+ MoO3 is formed, and each nanoparticle is anchored on the bacterial membrane surface. The nanoparticles act as active bridging agents, enhancing the adsorption and intercalation of fertilizer ions with the bacterial membrane phospholipid bilayer and outer membrane proteins, thus achieving functional modification of the bacterial membrane surface. Continued stirring after ultrasonic treatment can further promote the formation of NH4+. + With PO4 3- The interaction between fertilizer ions and the nanoparticle-membrane interface, including electrostatic attraction, hydrogen bonding and coordination intercalation, results in an adsorption rate of fertilizer ions greater than 90%, yielding a modified fertilizer solution with a nanoparticle layer loaded on the bacterial membrane surface.

[0013] Furthermore, the method for preparing the sustained-release carrier solution includes: β-Cyclodextrin was added to a water-alcohol mixture of silane coupling agent and heated under reflux at 50-70°C for 1-3 hours. The pH of the solution was adjusted to 8.0-9.0 to obtain a surface-functionalized cyclodextrin solution. The mass ratio of β-cyclodextrin to silane coupling agent was 1:(0.1-0.3). A surface-functionalized cyclodextrin solution is added to a biodegradable polymer dispersion system and stirred at 40-60°C for 0.5-2 hours to form a stable sustained-release carrier solution; wherein the biodegradable polymer is preferably polylactic acid, polycaprolactone, or a combination thereof.

[0014] Furthermore, the mass ratio of the slow-release carrier solution to the modified fertilizer solution is (1~3):1, and the mixture is stirred at 40~70℃.

[0015] In the above technical solution, a coated modified compound fertilizer with a slow-release interface was prepared. The slow-release interface was constructed by a composite slow-release carrier formed by surface-functionalized cyclodextrin and biodegradable polymer.

[0016] Furthermore, the layered inorganic minerals are dispersed in an aqueous solution and stirred at 40-60°C for 1-2 hours to allow for full expansion. Then, surface modifiers and complexing stabilizers are added, and the reaction is continued at 60-80°C for 1-3 hours to introduce functional groups on the surface of the layered inorganic minerals and regulate their interlayer structure. And / or, the layered inorganic minerals are bentonite, attapulgite, or a combination thereof; And / or, the surface modifier is a quaternary ammonium salt compound; And / or, the complexing stabilizer is a polycarboxylic compound or a metal complexing agent.

[0017] Furthermore, the preparation method of the gelling matrix solution includes: dissolving a natural polymer in water to form a gelling matrix solution, and stirring at 15~40℃ until completely dissolved to obtain the solution; wherein, the natural polymer includes chitosan, sodium alginate or a combination thereof; And / or, a coated modified compound fertilizer and an inorganic support phase are sequentially added to a gelling matrix solution, and ultrasonic treatment is performed for 5-15 minutes to obtain a multiphase composite sol. The multiphase composite sol is then added dropwise to a crosslinking solution, and crosslinking is performed for 10-30 minutes to form a gel microsphere precursor. After post-treatment, an in-situ modified bacterial membrane foliar fertilizer is obtained. Preferably, the crosslinking solution is a crosslinking solution containing divalent metal ions.

[0018] Furthermore, the post-treatment includes: washing with deionized water 1 to 3 times, allowing it to stand and cure at room temperature for 12 to 24 hours, and then drying it at 40 to 60°C.

[0019] In a second aspect, a bacterial membrane in-situ modified foliar fertilizer is provided, which is prepared using the method described in any one of the first aspects.

[0020] Compared with the prior art, the beneficial effects of the present invention are: (1) This invention uses ultrasonic cavitation as the core technology to induce metal ions to generate a nanoparticle modified layer on the surface of the bacterial membrane in situ, which effectively solves the problem of insufficient interaction between bacterial membrane and fertilizer ions in the traditional compound fertilizer preparation process and significantly enhances the interaction between ion-membrane interface. (2) This invention significantly improves the NH4+ content by using ultrasonic cavitation-induced nanostructure modification of the membrane surface. + With PO4 3- The adsorption and intercalation efficiency of fertilizer ions provides a structural basis for the stable slow release and directional transport of nutrients. (3) The in-situ modification process of the membrane surface carried out under ultrasonic cavitation conditions in this invention has a good protective effect on bacteria and enzyme systems, which can effectively maintain the survival rate of the composite bacteria and the activity of the composite enzymes, and realize the controllability and continuity of the nutrient release process. (4) The bacterial film in-situ modified foliar fertilizer prepared by the method of the present invention can provide a more balanced and continuous nutrient supply during the grain filling period of crops, and the crop yield can preferably be increased by 10-20%; (5) The method of the present invention has a clear process route, a green and simple preparation process, low energy consumption, and can be applied in conjunction with existing foliar fertilizer preparation processes. It has good process adaptability, research value and promotion prospects. Attached Figure Description

[0021] Figure 1These are comparative diagrams of the bacterial membrane surface structure in Example 1 and Comparative Example 1 of the present invention. (a) is a microscopic diagram of the bacterial membrane surface state in Comparative Example 1; (b) is a microscopic diagram of the bacterial membrane surface state after ultrasonic cavitation treatment in Example 1.

[0022] Figure 2 These are comparative images of the retention of the activity of the composite bacteria in Example 1 and Comparative Example 1 of the present invention. Among them, (a) is a scanning electron microscope (SEM) image of the bacterial membrane surface structure in Comparative Example 1; (b) is a SEM image of the bacterial membrane surface structure after ultrasonic cavitation treatment in Example 1; (c) is a laser confocal microscope (LSM) image of the activity state of the composite bacteria in Comparative Example 1; and (d) is a laser confocal microscope (LSM) image of the activity state of the composite bacteria after ultrasonic cavitation treatment in Example 1. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0024] It should be noted that, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0025] The compound bacterial powder of this invention includes one or more of spore-forming beneficial bacteria, preferably including Bacillus subtilis, Bacillus licheniformis, or a combination thereof; the compound enzyme preparation includes one or more of cell wall degradation-related enzymes and / or polysaccharide hydrolases, preferably including pectinase, cellulase, or a combination thereof; the nitrogen fertilizer is selected from urea, ammonium nitrate, ammonium sulfate, or a combination thereof; the phosphate fertilizer is selected from potassium dihydrogen phosphate, diammonium phosphate, monoammonium phosphate, or a combination thereof; and the potassium fertilizer is selected from potassium chloride, potassium sulfate, or a combination thereof.

[0026] The aforementioned compound microbial powder, compound enzyme preparation, nitrogen fertilizer, phosphate fertilizer, and potassium fertilizer can all be commercially available products, and their specific sources and models do not constitute a limitation of this invention.

[0027] Example 1

[0028] (1) Construction of the initial bioactive system.

[0029] Weigh out 8 parts of compound bacterial powder and 5 parts of compound enzyme preparation and premix them. Then add 35 parts of nitrogen fertilizer, 25 parts of phosphorus fertilizer and 25 parts of potassium fertilizer to obtain a mixture. Add the above mixture to Tween-20 aqueous solution to make the mass fraction of the mixture in the system about 25 wt%. Mix evenly under mechanical stirring and adjust the pH of the system to 7.0 to obtain the initial biological activity system for subsequent treatment.

[0030] (2) Introduction of metal ion source.

[0031] Manganese sulfate, ferric chloride, and sodium molybdate were added to the initial bioactive system obtained in step (1) to increase the Mn content in the system. 2+ Fe 3+ and Mo 6+ The final concentrations were 0.3 mmol / L, 0.4 mmol / L, and 0.1 mmol / L, respectively. The mixture was stirred at room temperature for 8 min to ensure uniform dispersion of the metal ions, resulting in a mixed metal ion system.

[0032] (3) In-situ modification of bacterial membrane surface induced by ultrasonic cavitation.

[0033] The metal ion mixture obtained in step (2) was placed in a probe-type ultrasonic device and subjected to ultrasonic treatment under continuous stirring. The ultrasonic frequency was 30 kHz, the power was 80 W, the treatment time was 20 min, the intermittent mode was adopted (every 5 min of ultrasonic treatment, paused for 1 min), and the reaction temperature was controlled at 30 ℃ and the stirring speed was 250 rpm.

[0034] Under ultrasonic cavitation, metal ions in the system undergo in-situ reactions on the bacterial membrane surface, forming metal oxide nanoparticles anchored to the bacterial membrane surface, thereby constructing a nanoparticle modified layer on the bacterial membrane surface.

[0035] (4) Membrane-ion synergistic stabilization treatment.

[0036] After ultrasonic treatment, the resulting system was stirred for another 12 minutes to promote the growth of NH4+. + PO4 3- The synergistic effect between fertilizer ions and the nanoparticle-modified layer on the bacterial membrane surface enables fertilizer ions to be stably bound to the bacterial membrane surface through electrostatic adsorption, hydrogen bonding, and coordination intercalation, resulting in a modified fertilizer solution with a nanoparticle layer loaded on the bacterial membrane surface.

[0037] (5) Construction of the sustained-release interface.

[0038] β-Cyclodextrin was added to a water-alcohol mixture of silane coupling agent and heated under reflux at 60°C for 2 hours. The pH of the solution was adjusted to 8.5 to obtain a functionalized cyclodextrin solution, wherein the mass ratio of β-cyclodextrin to silane coupling agent was 1:0.2.

[0039] The functionalized cyclodextrin solution was added to the polylactic acid dispersion system and stirred at 50°C for 1 hour to form a stable slow-release carrier solution. Then, the modified fertilizer solution obtained in step (4) was added to the slow-release carrier solution and mixed at a mass ratio of 2:1 between the slow-release carrier and the modified fertilizer solution. After stirring evenly, the mixture was freeze-dried to obtain the coated modified compound fertilizer.

[0040] (6) Construction of inorganic support phase.

[0041] Bentonite was dispersed in deionized water and stirred at 50°C for 1.5 h to achieve full expansion. Subsequently, a quaternary ammonium salt surface modifier and a polycarboxylated metal complexing agent were added, and the reaction was carried out at 70°C for 2 h. After the reaction, the system was filtered, washed, and dried to obtain an inorganic support phase for stabilizing the bacteria-nanocomposite system and regulating the migration behavior of fertilizer ions.

[0042] (7) Multiphase synergistic hydrogel carrier molding.

[0043] Chitosan and sodium alginate were dissolved in water at a mass ratio of 1:1 to form a gel matrix solution. The coated modified compound fertilizer obtained in step (5) and the inorganic support phase obtained in step (6) were added to the gel matrix solution in sequence, and the solution was treated under ultrasonic dispersion conditions for 10 min to obtain a uniform multiphase composite sol.

[0044] The multiphase composite sol was added dropwise to the calcium chloride crosslinking solution and crosslinked for 20 min to form a hydrogel microsphere precursor. The hydrogel microsphere precursor was then washed three times with deionized water, allowed to stand and solidify at room temperature for 20 h, and then dried at 50 °C to obtain the bacterial membrane in-situ modified foliar fertilizer.

[0045] Example 2

[0046] The difference between this embodiment and Embodiment 1 is that the concentration of the metal ions added in step (2) is adjusted, wherein Mn 2+ Fe 3+ and Mo 6+ The final concentrations were 0.2 mmol / L, 0.3 mmol / L, and 0.08 mmol / L, respectively; the remaining preparation steps and conditions were the same as in Example 1, and bacterial membrane in-situ modified foliar fertilizer was obtained.

[0047] Example 3

[0048] The difference between this embodiment and embodiment 1 is that the ultrasonic treatment parameters in step (3) are adjusted, the ultrasonic frequency is 25 kHz, the ultrasonic power is 70 W, and the ultrasonic treatment time is 15 min; the remaining preparation steps and conditions are the same as in embodiment 1, and bacterial membrane in-situ modified foliar fertilizer is obtained.

[0049] Example 4

[0050] The difference between this embodiment and embodiment 1 is that the ultrasonic treatment parameters in step (3) are adjusted, the ultrasonic frequency is 40 kHz, the ultrasonic power is 100 W, and the ultrasonic treatment time is 30 min; the remaining preparation steps and conditions are the same as in embodiment 1, and bacterial membrane in-situ modified foliar fertilizer is obtained.

[0051] Example 5

[0052] The difference between this embodiment and Example 1 is that the mass ratio of the slow-release carrier to the modified fertilizer in step (5) is adjusted to 1.5:1; the remaining preparation steps and conditions are the same as in Example 1, and the bacterial membrane in-situ modified foliar fertilizer is obtained.

[0053] Comparative Example 1 This comparative example is basically the same as Example 1, except that ultrasonic cavitation treatment is not performed. The specific steps are as follows.

[0054] (1) Construction of the initial bioactive system.

[0055] Weigh out 8 parts of compound bacterial powder and 5 parts of compound enzyme preparation and premix them. Then add 35 parts of nitrogen fertilizer, 25 parts of phosphorus fertilizer and 25 parts of potassium fertilizer to obtain a mixture. Add the above mixture to Tween-20 aqueous solution to make the mass fraction of the mixture in the system about 25 wt%. Mix evenly under mechanical stirring and adjust the pH of the system to 7.0 to obtain the initial biologically active system.

[0056] (2) Introduction of metal ion source.

[0057] Manganese sulfate, ferric chloride, and sodium molybdate were added to the initial bioactive system obtained in step (1) to increase the Mn content in the system. 2+ Fe 3+ and Mo 6+ The final concentrations were 0.3 mmol / L, 0.4 mmol / L, and 0.1 mmol / L, respectively. The mixture was stirred at room temperature for 8 min to ensure uniform dispersion of the metal ions in the system.

[0058] (3) Conventional stirring treatment (without ultrasonic cavitation).

[0059] The mixture obtained in step (2) was placed under normal stirring conditions and stirred at 30°C for 20 min at a stirring speed of 250 rpm without ultrasonic treatment.

[0060] (4) Membrane-ion interaction treatment.

[0061] After completing step (3), continue stirring the system for 12 min to promote the interaction between fertilizer ions such as NH4⁺ and PO4³⁻ and the bacterial membrane surface, and obtain a modified fertilizer solution.

[0062] (5) Construction of the sustained-release interface. The specific steps are the same as in Example 1.

[0063] (6) Construction of the inorganic support phase. The specific steps are the same as in Example 1.

[0064] (7) Multiphase synergistic hydrogel carrier molding. The specific steps are the same as in Example 1.

[0065] The foliar fertilizers prepared in Example 1 and Comparative Example 1 were characterized and tested.

[0066] like Figure 1 As shown in Figure (a), in Comparative Example 1, no obvious metal oxide nanoparticle deposition was observed on the bacterial membrane surface under conditions without ultrasonic cavitation treatment; Figure 1 As shown in (b), after ultrasonic cavitation treatment in Example 1, metal oxide nanoparticles were successfully loaded onto the surface of the bacterial membrane.

[0067] like Figure 2 As shown, the survival rate of the compound bacteria and the retention rate of the compound enzyme activity in Comparative Example 1 were both lower than those in Example 1. Further testing revealed that the survival rate of the compound bacteria in Example 1 was higher than 90%, the retention rate of the compound enzyme activity was higher than 85%, and the NH4+... + and PO4 3- The adsorption rate is greater than 90%; the fertilizer nutrient release process is gradual, with good slow-release performance. The adsorption rate and slow-release performance were obtained by testing the nutrient adsorption and release performance of foliar fertilizer samples.

[0068] Based on the foregoing analysis, it can be seen that, compared with Example 1, the foliar fertilizer obtained in Comparative Example 1 is weaker in terms of fertilizer ion adsorption capacity, slow release effect and overall fertilizer efficiency, indicating that ultrasonic cavitation treatment plays a key role in achieving in-situ modification and performance improvement of bacterial membrane surface in the technical solution of this invention.

[0069] Application Example 1 Using Chinese cabbage seedlings with uniform growth as experimental materials, a pot experiment was conducted under greenhouse conditions to verify the application effect of the foliar fertilizer in this invention on crop growth promotion and nutrient absorption.

[0070] Experimental setup: experimental group (foliar fertilizer prepared in Examples 1 to 3), control group (foliar fertilizer prepared in Comparative Example 1) and blank control group (water). The foliar fertilizers in the experimental group and the control group were diluted with water at the same concentration.

[0071] Experimental method: The foliar spray was applied to the surface of the leaves of the Chinese cabbage plants. The spray was applied once every 7 days during the middle and late stages of the growth of the Chinese cabbage, and the spraying was repeated for 3 times. All other cultivation and management conditions were kept the same.

[0072] The growth and quality indicators of Chinese cabbage were measured during the harvest period. The aboveground fresh weight, underground fresh weight, plant height, and leaf area were measured using conventional agronomic methods. The contents of soluble sugars, soluble proteins, and vitamin C in the leaves were measured using conventional analytical methods. The total nitrogen and total phosphorus contents of the plants were measured using standard chemical analytical methods to evaluate the crop's absorption and utilization of nutrients. The data for each indicator were the average of at least three repeated experiments. The results are shown in Table 1 below.

[0073] Table 1 Comparison of Application Effects

[0074] Table 1 shows that, compared with the blank control group, both the experimental group and the control group sprayed with foliar fertilizer promoted the growth of Chinese cabbage; further, compared with the control group, the experimental group showed a more significant improvement in all growth and quality indicators.

[0075] Compared with the control group, the experimental group showed an increase of approximately 22%, 39%, and 50% in the aboveground fresh weight of pak choi, and approximately 17%, 40%, and 53% in the underground fresh weight, respectively. Simultaneously, the experimental group's promotion of plant height and leaf area showed a similar trend to the fresh weight changes, both exhibiting significant improvements. Furthermore, with increasing application dosage, the growth-promoting effect on pak choi gradually increased, subsequently leveling off, indicating that the foliar fertilizer of this invention has a dose-dependent effect on the growth-promoting effect of pak choi.

[0076] Furthermore, the quality indicators of the experimental group of pak choy were significantly better than those of the control group. After applying the foliar fertilizer of this invention, the soluble sugar content in the pak choy leaves increased by approximately 14%, 21%, and 24%, respectively; the vitamin C content increased by approximately 13%, 19%, and 27%, respectively; and the soluble protein content increased by approximately 11%, 19%, and 24%, respectively. Simultaneously, the total nitrogen content of the plants increased by approximately 6%, 13%, and 20%, respectively, and the total phosphorus content increased by approximately 11%, 21%, and 30%, respectively, indicating that the foliar fertilizer of this invention can effectively improve the absorption and utilization efficiency of nitrogen and phosphorus nutrients by crops.

[0077] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a bacterial membrane-modified foliar fertilizer, characterized in that, Includes the following steps: The compound bacterial powder and compound enzyme preparation were premixed, and then nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer were added to obtain a mixture. An aqueous solution of surfactant was added to the mixture, and after stirring evenly, the pH was adjusted to obtain the initial biologically active system. Manganese ion source, iron ion source and molybdenum ion source were added to the initial bioactive system and stirred evenly to obtain a mixed metal ion system. A modified fertilizer solution with a nanoparticle layer loaded on the surface of a bacterial membrane was obtained by ultrasonic cavitation and stirring of a metal ion mixture system. The modified fertilizer solution was added to the slow-release carrier solution, stirred evenly, and then freeze-dried to obtain a coated modified compound fertilizer with a slow-release interface. Layered inorganic minerals were dispersed in an aqueous solution and stirred to expand. Then, surface modifiers and complexing stabilizers were added. After the reaction, the mixture was filtered, washed, and dried to obtain an inorganic supported phase. A coated modified compound fertilizer and an inorganic support phase were sequentially added to a gelling matrix solution, and ultrasonic treatment was performed to obtain a multiphase composite sol. The multiphase composite sol was then added dropwise to a crosslinking solution to form a gel microsphere precursor. After post-treatment, an in-situ modified foliar fertilizer with bacterial membrane was obtained.

2. The method for preparing bacterial membrane in-situ modified foliar fertilizer according to claim 1, characterized in that, The mass fractions of each component in the mixture are as follows: 5-10 parts of compound bacterial powder, 3-8 parts of compound enzyme preparation, 30-40 parts of nitrogen fertilizer, 20-30 parts of phosphate fertilizer, and 20-30 parts of potassium fertilizer. And / or, the mass fraction of the mixture in the surfactant aqueous solution is 20-30 wt%; And / or, the mixture is stirred evenly in an aqueous surfactant solution and the pH is adjusted to 6.5-7.

5.

3. The method for preparing the bacterial membrane in-situ modified foliar fertilizer according to claim 1, characterized in that, The manganese ion source is manganese sulfate, the iron ion source is ferric chloride, and the molybdenum ion source is sodium molybdate. And / or, add manganese ion source, iron ion source and molybdenum ion source to the initial bioactive system and stir for 5-10 min.

4. The method for preparing the bacterial membrane in-situ modified foliar fertilizer according to claim 1, characterized in that, In the initial bioactive system, the final concentration of manganese ions is 0.1–0.5 mmol / L, the final concentration of iron ions is 0.2–0.6 mmol / L, and the final concentration of molybdenum ions is 0.05–0.2 mmol / L.

5. The method for preparing bacterial membrane in-situ modified foliar fertilizer according to claim 1, characterized in that, Methods for ultrasonic cavitation and stirring of metal ion mixtures include: The metal ion mixture was placed in an ultrasonic bath or a probe-type ultrasonic instrument for ultrasonic treatment at a frequency of 20-40 kHz, a power of 50-100 W, and a treatment time of 10-30 min. An intermittent ultrasonic mode was used: a 1-min pause was taken after every 5 min of ultrasonic treatment. The reaction temperature was controlled at 25-40℃, and stirring was maintained at a speed of 200-300 rpm. After the ultrasonic treatment was completed, stirring was continued for 10-15 min.

6. The method for preparing bacterial membrane in-situ modified foliar fertilizer according to claim 1, characterized in that, The method for preparing the sustained-release carrier solution includes: β-Cyclodextrin was added to a water-alcohol mixture of silane coupling agent and heated under reflux at 50-70°C for 1-3 hours. The pH of the solution was adjusted to 8.0-9.0 to obtain a surface-functionalized cyclodextrin solution. The mass ratio of β-cyclodextrin to silane coupling agent was 1:(0.1-0.3). A surface-functionalized cyclodextrin solution was added to a biodegradable polymer dispersion system and stirred at 40-60°C for 0.5-2 hours to form a stable sustained-release carrier solution.

7. The method for preparing the bacterial membrane in-situ modified foliar fertilizer according to claim 1, characterized in that, The mass ratio of the slow-release carrier solution to the modified fertilizer solution is (1~3):1, and the mixture is stirred at 40~70℃.

8. The method for preparing the bacterial membrane in-situ modified foliar fertilizer according to claim 1, characterized in that, Layered inorganic minerals are dispersed in an aqueous solution and stirred at 40-60℃ for 1-2 hours to allow for full expansion. Then, surface modifiers and complexing stabilizers are added, and the reaction continues at 60-80℃ for 1-3 hours. And / or, the layered inorganic mineral is bentonite, attapulgite, or a combination thereof; And / or, the surface modifier is a quaternary ammonium salt compound; And / or, the complexing stabilizer is a polycarboxylic compound or a metal complexing agent.

9. The method for preparing bacterial membrane in-situ modified foliar fertilizer according to claim 1, characterized in that, The preparation method of the gelling matrix solution includes: dissolving a natural polymer in water to form a gelling matrix solution, and stirring at 15~40℃ until completely dissolved to obtain the solution; wherein, the natural polymer includes chitosan, sodium alginate or a combination thereof; And / or, add the coated modified compound fertilizer and the inorganic support phase sequentially to the gel matrix solution, and sonicate for 5-15 min to obtain a multiphase composite sol. Add the multiphase composite sol dropwise to the crosslinking solution and crosslink for 10-30 min to form a gel microsphere precursor. After post-treatment, obtain the bacterial membrane in-situ modified foliar fertilizer.

10. A bacterial film-modified foliar fertilizer, characterized in that, It is prepared by the method described in any one of claims 1 to 9.

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