Heavy metal and insect disease double-effect regulation type organic fertilizer and preparation process thereof

Abstract

The invention relates to the technical field of functional fertilizers, and discloses a heavy metal and insect disease double-effect regulation type organic fertilizer and a preparation process thereof, the fertilizer is a particle with a three-layer structure of core-inner layer coating-outer layer coating; the core is prepared from a composite passivation functional body, an organic nutrition matrix and a binder; the composite passivation functional body is a flavone-modified functional biological porous carrier loaded with strontium ion-doped nano-hydroxyapatite, and is used for fixing soil heavy metals and regulating and controlling rhizosphere micro-ecology; the inner-layer coating is prepared from wood vinegar, the outer-layer coating is prepared from chitosan oligosaccharide and sodium alginate, and the layered structure realizes sequential release of immune induction substances and synergistically induces plant resistance. Through specific structural design and component synergy, triple effects of heavy metal fixation, rhizosphere micro-ecological regulation and control and plant disease and insect pest induced resistance are achieved, and the effect is definite.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional fertilizers, in particular to a heavy metal and pest and disease double-effect regulation type organic fertilizer and a preparation process thereof. BACKGROUND

[0002] In current agricultural production, soil heavy metal pollution and frequent plant pest and disease are two main factors restricting crop yield and quality. To cope with the problem of soil heavy metal pollution, the existing technology usually adopts the way of applying a passivation agent to the soil, such as using phosphate materials, lime or biochar and other substances to reduce the biological availability of heavy metals through adsorption, precipitation or complexation. However, such passivation agents are usually mixed with soil or fertilizer in a simple physical way in application, which often leads to uneven distribution in the soil, and the active components are easily lost or consumed too early, so that the passivation efficiency is not high and the effect is not persistent.

[0003] In order to reduce the use of chemical pesticides, using exogenous inducers to stimulate the systemic resistance of plants has become an important pest and disease regulation strategy. Chitooligosaccharide, wood vinegar and other substances have been proved to be able to induce plant defense response as signal molecules. However, such inducers are unstable in soil environment and are easily degraded. If they are directly mixed with fertilizers for application, their release process is uncontrollable, usually showing a one-time explosive release, which is difficult to match with the key period of plant growth cycle that needs to be induced resistance, thereby limiting the stability and effectiveness of its application effect.

[0004] In the prior art, the preparation method of the composite functional fertilizer developed to solve the above two problems still stays at the level of simple mechanical blending of various functional materials. This preparation method cannot solve the potential antagonism between different functional components, nor can it realize the release of different functional components in time sequence according to their action mechanism. For example, the passivation function requires the components to exist stably in the soil for a long time, while the induction resistance function may require specific signal molecules to be released preferentially at a specific time point. Therefore, simple blending cannot form functional synergies, and the efficacy of each component is limited. SUMMARY

[0005] The technical problem to be solved by the present application is to provide an organic fertilizer capable of simultaneously realizing effective fixation of soil heavy metals and induction resistance regulation of plant pests and diseases, and a corresponding preparation process thereof.

[0006] To solve the above technical problems, the technical solutions of the present application are as follows: In a first aspect, the present application provides a heavy metal and pest and disease double-effect regulation type organic fertilizer, which adopts the following technical solutions: A heavy metal and pest dual-effect regulation type organic fertilizer, which is a particle with a layered structure, comprises, by weight fraction: 100 parts of a core; 5-15 parts of an inner layer coating covering the core; and 2.5-5.0 parts of an outer layer coating covering the inner layer coating; wherein the core comprises the following components by weight fraction: a composite passivation functional body: 5-15 parts; an organic nutrient substrate: 73-83 parts; a binder: 1-5 parts; the inner layer coating is made of wood vinegar; the outer layer coating is made of chitosan oligosaccharide and sodium alginate.

[0007] By adopting the above technical solution, the specific three-layer physical structure of the fertilizer and the chemical function synergy of the components of each layer work together. First, the composite passivation functional body in the core of the fertilizer, which contains strontium ion-doped nano-hydroxyapatite, fixes heavy metal ions (such as Cd 2+ ) in the soil in its crystal lattice or surface through ion exchange, surface complexation, and coprecipitation, etc., reducing its bioavailability. Second, the physical structure composed of the core, the inner layer coating, and the outer layer coating of the fertilizer realizes the time sequence release of the functional components in the soil water environment. After being applied to the soil, the chitosan oligosaccharide coating of the outermost layer is first slowly dissolved and released, which is recognized by the plant root system as a plant immune signal molecule, starting the plant's systemic acquired resistance. Subsequently, the wood vinegar coating of the inner layer is released, which contains organic acids and other substances that can not only adjust the rhizosphere microenvironment, but also act as another type of immune induction signal molecule, producing a synergistic effect with the chitosan oligosaccharide released earlier. This structure ensures that different functional components act on the target system at the right time point with effective concentration, avoiding the possible interaction or activity reduction of the components before release due to direct contact.

[0008] Preferably, the composite passivation functional body is a flavone-modified functionalized biological porous carrier loaded with strontium ion-doped nano-hydroxyapatite.

[0009] By adopting the technical scheme, the strontium ion-doped nano-hydroxyapatite is in-situ loaded on the flavone-modified functionalized bioporous carrier. On one hand, the large specific surface area and porous structure of the bioporous carrier provide the nano-hydroxyapatite with dispersed attachment sites, increase the contact area and reactivity of the nano-hydroxyapatite with heavy metal ions in the soil; on the other hand, the flavones loaded on the surface of the carrier can act as chemical signal molecules to direct the regulation of the structure and activity of the rhizosphere microbial community, promote the proliferation of beneficial microorganisms (such as phosphorus-solubilizing and potassium-solubilizing bacteria), and further improve the rhizosphere environment through microbial metabolic activities, thereby indirectly improving the health level and nutrient absorption efficiency of plants.

[0010] Preferably, the flavone-modified functionalized bioporous carrier is composed of mesoporous biochar and flavones loaded thereon; the flavones are quercetin and / or rutin; and / or the mesoporous biochar is prepared by pyrolysis of rice husks at a temperature of 450-650 DEG C.

[0011] By adopting the technical scheme, the mesoporous biochar prepared by selecting a specific pyrolysis temperature has a suitable pore size distribution and functional groups, which is beneficial to the stable loading of flavones and the subsequent loading of nano-hydroxyapatite. Quercetin or rutin is selected as the modifier because it has a definite microbial regulation function.

[0012] In a second aspect, the present application provides a preparation process of a heavy metal and pest and disease double-effect regulation type organic fertilizer, which adopts the following technical scheme: The preparation process of a heavy metal and pest and disease double-effect regulation type organic fertilizer as described above comprises the following steps: (a) core preparation: uniformly mixing a composite passivation functional body, an organic nutrient substrate and a binder, then granulating and drying to obtain core granules; (b) inner layer coating: placing the core granules obtained in step (a) in a fluidized bed, and spraying an inner layer coating liquid to form an inner layer coating; (c) outer layer coating: on the basis of the inner layer coated granules, continuously spraying an outer layer coating liquid to form an outer layer coating.

[0013] By adopting the technical scheme, the preparation process accurately constructs the functional gradient layered structure of the fertilizer through step-by-step operation. In step (a), the core components with heavy metal fixation and rhizosphere regulation functions are prepared into stable cores; in steps (b) and (c), the fluidized bed coating technology is adopted to realize the physical isolation and ordered coating of the inner and outer functional layers by sequentially spraying different coating liquids. The process flow ensures that the final product has the aforementioned time sequence release characteristics, which is a structural guarantee for realizing the dual functions. The process parameters are controllable, and the repeatability is good, which is suitable for industrial production.

[0014] Preferably, the composite passivation functional body used in step (a) is prepared by the following steps: dispersing the flavone-modified functionalized bioporous carrier in water to form a suspension, then adding calcium salt and strontium salt to the suspension under stirring, and adding a phosphate solution dropwise for in-situ precipitation reaction, and obtaining the reaction product after aging, separation and drying.

[0015] By adopting the above technical solution, the strontium ion-doped nano-hydroxyapatite is generated directly on the surface and in the pores of the flavone-modified functionalized bioporous carrier by using the in-situ precipitation method. Compared with simple physical mixing, this preparation method forms a more closely combined interface, ensuring the structural stability of the composite passivation functional body in the soil environment, and avoiding the rapid shedding or loss of active components.

[0016] In summary, the present application includes at least one of the following beneficial technical effects: 1. The organic fertilizer provided by the present application can effectively fix heavy metals in the soil through the composite passivation functional body in the core. The functional body loads the strontium ion-doped nano-hydroxyapatite on the bioporous carrier in-situ, increases the specific surface area and reaction sites of the active components, and reduces the bioavailability of heavy metals in the soil through ion exchange and surface complexation mechanisms, thereby reducing the absorption of heavy metals by crops.

[0017] 2. The present application realizes the time sequence release of functional components through the precisely constructed three-layer physical structure of core-inner layer coating-outer layer coating. The outer layer chitosan oligosaccharide and the inner layer pyroligneous liquid, as plant immune induction signal molecules, can be released in a predetermined order, and act synergistically on the plant roots to start and maintain the plant's systemic acquired resistance, thereby achieving the purpose of regulating plant diseases and insect pests, and avoiding the activity reduction of each active component due to direct contact during storage and initial application.

[0018] 3. The present application realizes the directional regulation of the rhizosphere microecology by modifying flavonoids on the bioporous carrier of the fertilizer core. Flavonoids as chemical signals can regulate the community structure and activity of beneficial microorganisms in the rhizosphere, promote nutrient transformation and absorption, and improve soil health, thereby fundamentally improving the growth potential of plants and their tolerance to biotic and abiotic stresses, and forming a beneficial additive effect with the passivation and induction functions. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with specific examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

[0020] The main raw materials and reagents used in the following examples and comparative examples are as follows, and the reagents not specifically described are commercially available analytical pure or higher grade products.

[0021] Worm castings: commercially available, organic fertilizer grade, with physicochemical indexes of organic matter content 40-45%, total nutrients (N+P2O5+K2O) ≥5.0%, pH 7.0-7.5.

[0022] Mineral humic acid: commercially available, powder, with physicochemical indexes of water-soluble humic acid content ≥70%, pH 8.0-9.0.

[0023] Wood vinegar stock solution: commercially available, forestry grade, with physicochemical indexes of pH 2.5-3.5, total organic acid content (calculated as acetic acid) 3-7% (w / v).

[0024] Sodium alginate: CAS No. 9005-38-3; commercially available, food grade, with a viscosity of 200-500 mPa·s at 20℃ for a 1% aqueous solution, used as a film-forming agent.

[0025] Chitosan oligosaccharide: The chitosan oligosaccharide used in the present application is an oligomer mixture prepared by chitosan enzymatic hydrolysis or acid hydrolysis, with key performance parameters of number average molecular weight (Mn) in the range of 500-3000 Da, and deacetylation degree ≥90.0%.

[0026] Flavone-modified functionalized bioporous carrier: non-commercial substance, the specific preparation method is described in detail in Preparation Example 1.

[0027] Composite passivation functional body: non-commercial substance, the specific preparation method is described in detail in Preparation Example 2.

[0028] Preparation Example 1: The present preparation example provides a preparation method of a flavone-modified functionalized bioporous carrier, comprising the following steps: 1) Preparation of mesoporous biochar: 1 kg of dry and clean rice husk was placed in a tube furnace, heated to 550℃ at a heating rate of 10℃ / min under nitrogen protection (nitrogen flow rate 200 mL / min), and pyrolyzed at this temperature for 2 hours. After natural cooling to room temperature, the carbonized product was taken out, ground with a pulverizer and passed through a 150 mesh sieve to obtain mesoporous biochar powder.

[0029] 2) Surface modification: Accurately weigh 1.0 g of quercetin and dissolve it in 1 L of anhydrous ethanol to prepare a modified solution with a concentration of 1.0 g / L. Weigh 300 g of the mesoporous biochar powder prepared in step (1) and add it to 9 L of the modified solution to achieve a solid-to-liquid ratio of 1:30 (g:mL). Stir the reaction continuously at 40°C using a magnetic stirrer for 18 hours.

[0030] 3) Product post-processing: After the reaction, the solid product was collected by filtration. The solid product was washed four times with anhydrous ethanol to fully remove unsupported quercetin. The washed solid was dried in a vacuum oven at 70°C for 10 hours to obtain a flavonoid-modified functionalized bioporous carrier powder, which was then sealed and stored for later use.

[0031] Preparation Example 2: This preparation example provides a method for preparing a composite passivation functional body, comprising the following steps: 1) Carrier dispersion: 100 g of the flavonoid-modified functionalized bioporous carrier powder prepared in Preparation Example 1 was weighed and added to 1 L of deionized water. The powder was ultrasonically treated at a power of 200 W and a frequency of 30 kHz for 30 minutes to form a uniform suspension.

[0032] 2) In situ precipitation reaction: Weigh 35.4 g of calcium nitrate tetrahydrate and 3.5 g of strontium nitrate and dissolve them in 500 mL of deionized water to prepare a calcium-strontium mixed solution (Solution A). Separately weigh 13.2 g of diammonium hydrogen phosphate and dissolve them in 500 mL of deionized water to prepare a phosphorus source solution (Solution B). Add Solution A to the biochar suspension from step (1) and stir evenly. Under continuous stirring, use a peristaltic pump to slowly add Solution B to the mixed suspension at a rate of 5 mL / min. During the addition process, use 1.0 mol / L sodium hydroxide solution to adjust and maintain the pH of the reaction system at 10.5.

[0033] 3) Aging: After the dropwise addition was completed, the mixed slurry was stirred and reacted in a water bath at 50° C. for 24 hours for aging.

[0034] 4) Product post-processing: After aging, the slurry was filtered. The filter cake was repeatedly washed with deionized water until the filtrate was neutral, and then washed twice with anhydrous ethanol. The resulting filter cake was vacuum dried at 70°C for 12 hours and finally ground to obtain a composite passivation functional body powder, which was sealed and stored for later use.

[0035] Example 1

[0036] This embodiment provides a method for preparing an organic fertilizer with dual effects of heavy metal passivation and pest control, comprising the following steps: 1) Core preparation: Weigh 10 kg of the composite passivation functional body powder prepared in Preparation Example 2, 73 kg of vermicompost, 5 kg of mineral humic acid, and 2 kg of calcium lignosulfonate. Put the above materials into a horizontal mixer and mix for 15 minutes until uniform. Put the mixed materials into a pair roller extrusion granulator for granulation, and control the average particle size of the granules to be 3.0 mm. Dry the prepared wet granules in a hot air at 60°C to reduce the moisture content of the granules to 20%.

[0037] 2) Layered coating: Put 90 kg of the core granules prepared in step (1) into a fluidized bed coating machine.

[0038] Inner layer coating: Set the fluidized bed air inlet temperature to 70°C, and stabilize the particle bed temperature at 45°C. Dilute the wood vinegar stock solution with deionized water by 2 times to obtain the inner layer coating solution. Spray the coating solution uniformly onto the surface of the granules at a rate of 15 mL / min / kg through an atomizing spray gun, and spray a total of 4.5 kg of the coating solution.

[0039] Outer layer coating: After the inner layer coating is completed, switch the coating solution. Prepare the outer layer coating solution: dissolve 3 kg of chitosan oligosaccharide and 1 kg of sodium alginate in water, and make up to 50 L. Set the fluidized bed air inlet temperature to 65°C, and stabilize the particle bed temperature at 40°C. Spray the outer layer coating solution at a rate of 15 mL / min / kg until the spraying is completed.

[0040] 3) Post-treatment: Dry the coated fertilizer granules at a low temperature of 45°C until the total moisture content of the finished product is less than 10%. After drying, stack the granules at room temperature for 5 days for curing. Finally, screen the granules through a drum screen, and collect the finished product with a particle size of 2.0-4.0 mm to obtain about 100 kg of the final product.

[0041] Example 2

[0042] This example is basically the same as Example 1, except that: In the preparation of the composite passivation functional body (Preparation Example 2), the molar ratio of Sr / (Sr+Ca) in the calcium-strontium mixed solution (solution A) is adjusted to 5%.

[0043] In the core preparation step (1), the amount of the composite passivation functional body is 5 kg, the amount of vermicompost is 78 kg, the amount of mineral humic acid is 5 kg, and the amount of calcium lignosulfonate is 2 kg.

[0044] The remaining preparation steps and parameters are the same as those of Example 1.

[0045] Example 3

[0046] This example is basically the same as Example 1, except that: In the 1) core preparation step, the amount of composite passivation functional body used is 15 kg, the amount of earthworm manure used is 68 kg, the amount of mineral humic acid used is 5 kg, and the amount of calcium lignosulfonate used is 2 kg.

[0047] The remaining preparation steps and parameters are the same as those of Example 1.

[0048] Example 4

[0049] This example is basically the same as Example 1, except that: In the preparation of the flavone-modified functionalized biological porous carrier (Preparation Example 1), the 1) mesoporous biochar preparation step, the pyrolysis temperature is set to 450℃; (2) surface modification step, the flavone used is rutin.

[0050] The remaining preparation steps and parameters are the same as those of Example 1.

[0051] Example 5

[0052] This example is basically the same as Example 1, except that: In the preparation of the flavone-modified functionalized biological porous carrier (Preparation Example 1), the 1) mesoporous biochar preparation step, the pyrolysis temperature is set to 650℃.

[0053] The remaining preparation steps and parameters are the same as those of Example 1.

[0054] Example 6

[0055] This example is basically the same as Example 1, except that: In the 2) layered coating step: Inner layer coating: The wood vinegar stock solution is diluted 1-fold with deionized water to serve as the inner layer coating solution, and a total of 8 kg of the coating solution is sprayed.

[0056] Outer layer coating: The outer layer coating solution formulation is as follows: 2 kg of chitosan oligosaccharide and 0.5 kg of sodium alginate are dissolved in water, and the volume is made up to 50 L.

[0057] The remaining preparation steps and parameters are the same as those of Example 1.

[0058] Comparative Example 1: Compared with Example 1, the difference is that no layered coating is performed. All solid components (composite passivation functional body, earthworm manure, mineral humic acid, calcium lignosulfonate, chitosan oligosaccharide, sodium alginate) used in the core preparation and coating of Example 1, as well as the wood vinegar stock solution, are added to the horizontal mixer at one time for physical dry mixing before granulation, and then directly granulated into the final product.

[0059] Comparative Example 2: The difference compared with Example 1 is that the functional passivation material used in the core preparation is different. Instead of the composite passivation functional body in Example 1, a physical mixture (weight ratio 1:1) of 10 kg of ordinary, unmodified mesoporous biochar (preparation method same as Step 1 of Preparation Example 1) and commercially available ordinary nano-hydroxyapatite powder is used. The remaining preparation steps and parameters are the same as Example 1.

[0060] Comparative Example 3: The difference compared with Example 1 is that the functional gradient layer structure is missing, but the envelope is retained. The inner envelope liquid (diluted vinegar solution) and the outer envelope liquid (chitosan oligosaccharide solution) in Example 1 are mixed uniformly beforehand, and then the core particles are sprayed with the envelope liquid as a whole. The remaining preparation steps and parameters are the same as Example 1.

[0061] Comparative Example 4: The difference compared with Example 1 is that in Preparation Example 1, step 2) of surface modification is not performed, i.e. the composite passivation functional body is prepared using unmodified mesoporous biochar. The remaining preparation steps and parameters are the same as Example 1.

[0062] Comparative Example 5: The difference compared with Example 1 is that in Preparation Example 2, strontium nitrate is not added to the A solution of step (2), i.e. the composite passivation functional body is prepared without doping strontium ions. The remaining preparation steps and parameters are the same as Example 1.

[0063] Comparative Example 6: The difference compared with Example 1 is that a simple physical mixture of the prior art is used. 78 kg of commercially available ordinary organic fertilizer (equivalent to the total amount of Example 1's earthworm manure + humic acid nutrient substrate) is mixed and granulated with 10 kg of the composite passivation functional body of Preparation Example 2. When applied in the field, 12.5 kg of commercially available mixed water agent of chitosan oligosaccharide and vinegar solution (solid content equivalent to Example 1) is diluted and applied together with the fertilizer.

[0064] Test Example 1: Heavy metal passivation performance evaluation The test steps are as follows: 1) Preparation and aging of simulated contaminated soil: Take uncontaminated loam soil (type: sandy loam soil), dry in the air, and pass through a 2 mm sieve. Weigh the dried and sieved soil, calculate the required amount of Cd 2+ added according to the weight of the soil, and uniformly spray and mix with Cd(NO3)2 solution to make the final exogenous addition concentration of Cd in the soil 5.0 mg / kg. Adjust the soil moisture content to 60% of the field water holding capacity and place it in a 25°C constant temperature incubator for 30 days of light-free aging.

[0065] 2) Sample treatment and incubation: The aged contaminated soil was divided into 1 kg portions. The fertilizer samples prepared in Examples 1-6 and Comparative Examples 1-6 were added into each portion of soil at a ratio of 1% of the dry soil weight (i.e. 10 g per portion), and mixed evenly. Another portion of the contaminated soil without any fertilizer was set as a blank control. Three replicates were set for each treatment. All the soil samples of the treatments were placed in a constant temperature incubator at 25°C, and maintained at a water content of 60% of the field capacity, and incubated for 60 days.

[0066] 3) Extraction and determination of available heavy metals: After the incubation, soil samples were taken from each treatment, air-dried, and ground through a 100 mesh sieve. 10.0 g of the soil sample was accurately weighed into a 50 mL centrifuge tube, and 20.0 mL of DTPA extraction solution (0.005 mol / L DTPA + 0.01 mol / L CaCl2+ 0.1 mol / L TEA, pH 7.3) was added. The tube was shaken horizontally at 180 r / min for 2 hours at 25°C. After the shaking, the solution was filtered through a quick filter paper. The concentration of Cd in the filtrate was determined by inductively coupled plasma mass spectrometry (ICP-MS).

[0067] Data calculation: The heavy metal passivation rate (%) was calculated according to the following formula: passivation rate = [(blank control group available Cd content - treatment group available Cd content) / blank control group available Cd content] x 100%.

[0068] The test results are shown in Table 1. Table 1: Effect of different treatments on the DTPA extractable Cd content in soil and passivation rate Treatment group DTPA extractable Cd content (mg / kg) Passivation rate (%) Blank control 5.23 0 Example 1 0.71 86.4 Example 2 1.14 78.2 Example 3 0.6 88.5 Example 4 0.82 84.3 Example 5 0.75 85.7 Example 6 0.91 82.6 Comparative Example 1 2.38 54.5 Comparative Example 2 3.81 27.2 Comparative Example 3 1.95 62.7 Comparative Example 4 1.33 74.6 Comparative Example 5 1.19 77.2 Comparative Example 6 4.12 21.2 The data in Table 1 shows that the DTPA extractable Cd content in the soil of the treatment groups of Examples 1-6 is lower than that of the blank control group and the treatment groups of Comparative Examples 1-6, and the highest passivation rate is obtained. This result is related to the specific composition of the complex passivation functional body in the core of the fertilizer. In the functional body, the strontium ion-doped nano-hydroxyapatite fixes Cd 2+ through ion exchange and co-precipitation, and the mesoporous biochar carrier provides physical adsorption sites. The combination of the above mechanisms achieves efficient fixation of the bioavailable Cd in the soil. The data of Examples 2-6 shows that changing the amount of components or the type of raw materials within the defined parameter range can also achieve effective Cd fixation.

[0069] Comparative Example 1 has much higher passivation rate than Comparative Examples 2 and 6, which are physical mixture of the components or field mixing, respectively. This indicates that the composite structure formed by in-situ precipitation of strontium ion doped nano-hydroxyapatite on the modified biochar carrier has a Cd fixation capacity that is not the arithmetic sum of the components. Comparative Example 1 has much higher passivation rate than Comparative Examples 1 and 3, which are granulation of all components or using mixed coating liquid, respectively. This confirms the necessity of the functional gradient layered structure for maintaining the activity of the core passivation function, which can avoid direct contact between the core function and the outer layer of active substances.

[0070] Comparative Example 1 has much higher passivation rate than Comparative Examples 4 and 5, which can confirm the technical contribution of specific components. Comparative Example 5 (without Sr doping) has lower passivation rate than Example 1, indicating that the doping of Sr ions changes the lattice structure of hydroxyapatite, increasing the fixation point or binding capacity of Cd 2+ Comparative Example 4 (without flavonoid modification) also has lower passivation rate than Example 1, indicating that the change in the surface chemical properties of the biochar carrier by flavonoids has a synergistic effect on the stability of the entire passivation system and the final Cd fixation effect.

[0071] Test Example 2: Evaluation of Plant Immune Induction Activity The test steps are as follows: 1) Experimental preparation and seedling raising: Select tomato (variety: Zhuzi No. 9) as the indicator plant. Fill the nutrient pots with a size of 10 cm x 10 cm with seedling raising substrate. Sow 3 seeds per pot, and when the seedlings grow to two leaves and one heart, thin them out, and keep one healthy seedling per pot with consistent growth. Place all seedlings in a light incubator and set the conditions as follows: temperature 25℃ / 18℃ (day / night), light 14h / d, relative humidity 70%.

[0072] 2) Sample treatment: Treat the tomato seedlings when they grow to four leaves and one heart. Mix the fertilizer samples prepared in Examples 1-6 and Comparative Examples 1-6 with the substrate at a ratio of 1:100 (w / w) and apply them evenly to the nutrient pots. Set up a group without any fertilizer as a blank control. Each treatment has three replicates.

[0073] 3) Pathogen inoculation: Continue to culture for 7 days after treatment. Prepare a spore suspension of Botrytis cinerea and adjust its concentration to 1×10 6 Using a spray method, evenly spray the spore suspension on the leaves of the tomato plants until the leaves are covered with droplets.

[0074] 4) Sample collection and enzyme activity determination: 48 hours after inoculation, the 3rd-4th functional leaves at the top of each plant were collected. 0.5 g of fresh leaves were accurately weighed and added with 5 mL of pH 7.8 phosphate buffer, and then grinded under ice bath condition. The homogenate was centrifuged at 12000 r / min for 15 minutes at 4°C, and the supernatant was taken as the crude enzyme solution. The activities of peroxidase (POD) and polyphenol oxidase (PPO) in the supernatant were determined by guaiacol method and catechol method, respectively, using a spectrophotometer.

[0075] The test results are shown in Table 2: Table 2: Effect of different treatments on the defense enzyme activities of tomato leaves after inoculation Treatment group POD activity (U g -1 · min -1 )]]> PPO activity (U g -1 · min -1 )]]> Blank control 51.4 112.7 Example 1 152.8 358.1 Example 2 134.6 321.5 Example 3 161.2 373.4 Example 4 148.5 340.9 Example 5 155 366.2 Example 6 127.9 295.3 Comparative Example 1 73.1 145.8 Comparative Example 2 115.6 253 Comparative Example 3 96.7 218.6 Comparative Example 4 121.3 289.4 Comparative Example 5 131.8 317.7 Comparative Example 6 62.5 128.9 The data in Table 2 show that, compared with the blank control group and each proportion group, the activities of peroxidase and polyphenol oxidase in the tomato leaves of the treatment groups of Examples 1-6 are at a higher level. This result shows that, after the specific components in the fertilizer samples are recognized by the plants, the defense response signal pathway in the plant body is activated, thereby leading to an increase in the synthesis amount of defense-related proteins. This active substance is derived from the pyroligneous acid and chitosan on the outer layer of the fertilizer particles, which act as signal molecules and directly act on the plant roots.

[0076] The comparison results of Example 1 and Comparative Examples 1 and 3 confirm the necessity of the functional gradient layered structure. The enzyme activities of the treatment groups of Comparative Example 1 (all components physically dry-mixed) and Comparative Example 3 (the coating liquid is mixed and then sprayed at one time) are significantly lower than that of Example 1. This shows that, through the specific structure formed by the layered coating, the external active substances (pyroligneous acid and chitosan) can be released preferentially after the fertilizer is applied, avoiding the physical and chemical action with the core functional body before release, which leads to a decrease in activity. This time sequence release is a prerequisite for achieving efficient induction of plant defense response.

[0077] The comparison results of Example 1 and Comparative Example 4 confirm the contribution of specific components to the overall effect. The enzyme activity of the treatment group of Comparative Example 4 (the core biochar is not modified by flavones) is lower than that of Example 1, which shows that the surface chemical properties of the core component also have an impact on the final biological effect. Although pyroligneous acid and chitosan are direct signal molecules, the flavone-modified biochar carrier can indirectly affect the absorption efficiency or response strength of the plant to the signal molecules by adjusting the rhizosphere environment, thereby producing a synergistic effect between the components and jointly leading to the enzyme activity level measured in the example.

[0078] Test Example 3: Evaluation of the time sequence release characteristics of functional components The test steps are as follows: 1) Experimental setup and preparation: Static water immersion method was adopted. Multiple 250 mL conical flasks with stoppers were taken, and 100 mL of deionized water was added to each conical flask.

[0079] 2) Sample handling and immersion: 10.0 g of fertilizer granules prepared from Example 1, Comparative Example 1 and Comparative Example 3 were accurately weighed and added to the conical flasks containing deionized water, respectively, immediately sealed and timing started. All the conical flasks were placed in a constant temperature shaker at 25°C, and oscillated at a low speed of 50 r / min to simulate the diffusion in a static water environment.

[0080] 3) Timed sampling: At the time points of 0.5 h, 2 h, 8 h, 24 h, 72 h, 168 h, 5 mL of supernatant was taken from each conical flask, filtered through a 0.45 μm filter membrane and stored for testing. After each sampling, 5 mL of deionized water was added to the conical flask to maintain the total liquid volume unchanged.

[0081] 4) Component determination: Total organic acid determination: Acid-base titration method was used to determine the total organic acid content in the supernatant, which was used as an indicative index of vinegar release.

[0082] Chitosan oligosaccharide determination: UV spectrophotometry was used to determine the concentration of chitosan oligosaccharide by the absorbance value after the reaction of chitosan oligosaccharide with a specific color reagent.

[0083] 5) Data calculation: According to the measured concentration and total liquid volume, the cumulative release rate of each functional component at each time point was calculated. Cumulative release rate (%) = (total amount of component released at current time point / total content of this component in the fertilizer sample) x 100%.

[0084] The test results are shown in Table 3: Table 3 Cumulative release rate (%) of functional components in different treated fertilizer granules: Time (h) Example 1 - total organic acids Example 1 - chitooligosaccharides Comparative Example 1 - total organic acids Comparative Example 1 - chitooligosaccharides Comparative Example 3 - total organic acids Comparative Example 3 - chitooligosaccharides 0.5 45.3 6.8 21.7 18.5 32.6 30.1 2 78.1 15.2 24.1 22.8 48.9 45.4 8 91.5 28.7 26.3 25 65.7 64.3 24 94.6 53.4 28.9 27.6 82.1 83.5 72 95.8 81.9 30.1 29.5 86.4 87 168 96.2 92.5 31.5 30.8 87.3 88.1 The data in Table 3 objectively show the release behavior of functional components in different structural fertilizer granules in water environment. For the sample of Example 1, the total organic acid (representing the inner layer coating) is rapidly released at the initial stage (0.5-8 h), and the cumulative release rate exceeds 90% at 8 hours; while the release of chitosan oligosaccharide (representing the outer layer coating) shows obvious delay and sustained-release characteristics, and the release rate is more than 50% only after 24 hours. The significant difference in the release curves directly confirms the existence of functional gradient layered structure in the fertilizer granules and realizes the time-sequential release of components.

[0085] Comparative Example 1 and Comparative Example 1, the two functional components in Comparative Example 1 (all components physically mixed) showed extremely low release rates with no significant difference. This indicates that after physical mixing, most of the active components are wrapped inside the fertilizer particles and cannot be effectively released. The results of Comparative Example 1 and Comparative Example 3, the release curves of the two components in Comparative Example 3 (sprayed once after mixing the coating liquid) are basically coincident, both showing rapid release, losing the timing. This further confirms that only through a specific step-by-step coating process can a structure with internal and external functional separation be constructed.

[0086] This physical structure constructed by the layered coating process is the basis for achieving the expected technical effect. The structure ensures that the outer layer material (such as chitosan) forms a physical barrier, so that the inner layer material (such as vinegar) can only come into contact with the environment after it is dissolved and released, thus forming a sequence in the release time. This time sequence release feature directly corresponds to the heavy metal fixation effect and plant defense response induction effect observed in Test Example 1 and Test Example 2, proving the causal relationship between structure and function.

[0087] Test Example 4: Evaluation of rhizosphere microecological regulation effect The test steps are as follows: 1) Experimental preparation and sample treatment: The experiment uses a potting method. The fertilizer samples prepared in Examples 1-6 and Comparative Examples 1-6 are mixed with 2 kg of sieved and air-dried loamy soil at a ratio of 1:100 (w / w) and evenly mixed into plastic pots. Another group without any fertilizer is set as a blank control. Three replicates are set for each treatment.

[0088] 2) Planting and cultivation: One tomato seedling (four-leaf-one-heart stage) with consistent growth state is transplanted into each pot. All pots are placed in a greenhouse for regular cultivation and management for 30 days.

[0089] 3) Collection of rhizosphere soil samples: After cultivation, the plants are removed completely and the loose soil attached to the roots is shaken off gently. The soil closely attached to the root surface is collected using a sterile brush, which is the rhizosphere soil sample. The rhizosphere soil samples of the three replicates of the same treatment are mixed evenly.

[0090] 4) Determination of soil enzyme activity: Urease activity determination: Phenol sodium-sodium hypochlorite colorimetric method. Accurately weigh 5.0 g of fresh rhizosphere soil sample, add 10% urea solution and pH 6.7 phosphate buffer, and incubate at 37°C for 24 hours. Determine the generation amount of ammonium nitrogen in the culture solution.

[0091] Phosphatase activity determination: Phosphorus di-sodium phenylate colorimetric method was used. 5.0 g of fresh rhizosphere soil sample was accurately weighed, and phosphorus di-sodium phenylate solution and modified universal buffer solution with pH 6.5 were added, and incubated at 37°C for 2 hours. The phenol content generated in the solution was determined.

[0092] The test results are shown in Table 4: Table 4: Effect of different treatments on the enzyme activity of tomato rhizosphere soil: Treatment group urease activity (mg NH4 + N·g -1 ·24h -1 )]]> Phosphatase activity (mg C6H5OH-g -1 ·2h -1 )]]> Blank control 0.18 1.27 Example 1 0.62 4.81 Example 2 0.53 3.98 Example 3 0.69 5.23 Example 4 0.58 4.66 Example 5 0.65 4.95 Example 6 0.59 4.47 Comparative Example 1 0.25 1.83 Comparative Example 2 0.31 2.15 Comparative Example 3 0.39 2.88 Comparative Example 4 0.42 3.19 Comparative Example 5 0.59 4.72 Comparative Example 6 0.21 1.54 The data in Table 4 objectively reflect the effect of different treatments on the enzyme activity of plant rhizosphere soil. The urease and phosphatase activities of the treatment groups of Examples 1-6 are significantly higher than those of the blank control group and the comparative examples. Soil enzyme activity is a key indicator for evaluating the overall activity of soil microbial flora. The increase in urease and phosphatase activity indicates an acceleration of the nitrogen and phosphorus conversion cycle in the soil. This result shows that the fertilizer provided by the technical solution can effectively regulate the rhizosphere microenvironment and promote the proliferation and metabolic activity of beneficial microorganisms.

[0093] The generation of this effect is directly related to the specific design of the core component of the fertilizer. The functionalized biological porous carrier in the core is modified on the surface by flavonoids. Flavonoids act as chemical signal molecules in the soil environment and can affect the chemotaxis and colonization behavior of specific microorganisms. At the same time, the porous structure of mesoporous biochar itself provides a physical shelter for microorganisms to attach and reproduce, and the organic nutrient substrate (such as worm manure) in the core provides a sustained carbon source and energy for the colonized microbial community. The combination of the three forms the basis for the directional regulation of beneficial microorganisms in the rhizosphere.

[0094] Comparing the data of Comparative Example 1 and Comparative Example 4 (core biochar not modified by flavones), the enzyme activity of the treatment group of Comparative Example 4 is significantly lower than that of Example 1, which directly confirms that the flavone surface modification plays a decisive role in regulating microbial activity. Comparing Example 1 with Comparative Example 1 (all components physically mixed), the enzyme activity of Comparative Example 1 has a small increase, indicating that disordered physical mixing cannot form a stable microzone conducive to microbial growth, and may even inhibit their activity due to local chemical environment imbalance. Therefore, it is the specific combination of flavone-modified functionalized carriers and organic nutrient substrates, and the existence of stable core structure, that realizes the effective and directional regulation of the rhizosphere microecology.

[0095] In summary, the experimental results of Test Examples 1-4 demonstrate from multiple aspects that the technical solution can achieve the technical effects.

[0096] The data of Test Example 1 shows that the passivation rate of DTPA extractable Cd in soil by the fertilizer prepared by the method of the embodiment is significantly higher than that of each comparative example. This effect is directly related to the composite passivation functional body in the core, which is composed of a biological porous carrier modified by flavones and strontium ion-doped nanohydroxyapatite generated in situ. Compared with samples using ordinary physical mixing components (Comparative Example 2) or lacking specific modified / doped components (Comparative Examples 4 and 5), the passivation performance of the embodiment shows the necessity of its specific structure.

[0097] The data of Test Example 3 confirms that the functional gradient structure constructed by the layered coating process can achieve the time sequence release of components, that is, the components in the inner layer of the coating are released quickly in priority, and the components in the outer layer of the coating show delayed and slow release. This physical release characteristic directly corresponds to the biological results of Test Example 2. In Test Example 2, the plant defense enzyme activity of the embodiment treatment group is significantly higher than that of the physical dry mixing (Comparative Example 1) or mixed coating (Comparative Example 3) treatment groups, both of which cannot achieve the time sequence release of components. This shows that the specific layered structure is the structural basis for ensuring the effective induction of plant defense response by external signal molecules.

[0098] In addition, the data of Test Example 4 shows that the rhizosphere soil enzyme activity of the embodiment treatment group is significantly improved. Compared with Comparative Example 4 using a biological charcoal core not modified by flavones, the difference in enzyme activity confirms the direct effect of the biological porous carrier modified by flavones in the fertilizer core on regulating the activity of the rhizosphere microecology. The comprehensive results show that by combining the specific core component design and the functional gradient layered structure, the dual technical effects of heavy metal fixation and plant physiological process regulation are finally achieved.

[0099] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. Heavy metal and pest control dual-effect organic fertilizer, characterized in that: The particles have a layered structure, and the particles comprise, by weight: 100 cores; 5 to 15 parts of an inner layer of film covering the core; and 2.5 to 5.0 parts of an outer layer of film coated outside the inner layer of film; Wherein, the core comprises the following components in parts by weight: Composite passivation functional body: 5-15 parts; Organic nutrient matrix: 73-83 parts; Binder: 1-5 parts; The inner layer of the coating is made of wood vinegar; The outer layer coating is made of chitosan oligosaccharide and sodium alginate.

2. The heavy metal and pest control dual-effect organic fertilizer according to claim 1, characterized in that: By weight, the particles comprise: 100 parts of a core, which is composed of 10 parts of a composite passivation functional body, 78 parts of an organic nutrient matrix and 2 parts of a binder; 5 parts of the inner coating; and 4.4 parts of the outer coating.

3. The heavy metal and pest control dual-effect organic fertilizer according to claim 1, characterized in that: The composite passivation functional body is a flavone-modified functional biological porous carrier loaded with strontium ion-doped nano-hydroxyapatite.

4. The heavy metal and pest control dual-effect organic fertilizer according to claim 3, characterized in that: The flavonoid-modified functionalized biological porous carrier consists of mesoporous biochar and flavonoid substances immobilized thereon.

5. The heavy metal and pest control dual-effect organic fertilizer according to claim 4, characterized in that: The flavonoids are quercetin and / or rutin; and / or the mesoporous biochar is prepared by pyrolysis of rice husk at a temperature of 450-650°C.

6. A preparation process of the heavy metal and pest control dual-effect organic fertilizer according to any one of claims 1 to 5, characterized in that: The following steps are involved: (a) Core preparation: The composite passivation functional body, the organic nutrient matrix, and the binder are uniformly mixed, and then granulated and dried to obtain core particles; (b) Inner coating: placing the core particles obtained in step (a) in a fluidized bed and spraying the inner coating liquid to form an inner coating; (c) Outer coating: On the basis of the particles forming the inner coating, the outer coating liquid is continued to be sprayed to form the outer coating.

7. The preparation process according to claim 6, characterized in that: The composite passivation functional body used in step (a) is prepared by the following steps: dispersing the flavonoid-modified functionalized bioporous carrier in water to form a suspension, then adding calcium salt and strontium salt to the suspension under stirring, and adding a phosphate solution dropwise to perform an in-situ precipitation reaction, and the reaction product is obtained after aging, separation and drying.

8. The preparation process according to claim 7, characterized in that: The flavonoid-modified functionalized bioporous carrier is prepared by the following steps: adding mesoporous biochar powder to an ethanol solution containing flavonoids, stirring and reacting at 30-50° C. for 12-24 hours, and obtaining a reaction product after separation, washing and drying.

9. The preparation process according to claim 6, characterized in that: In step (b), the temperature of the particle bed layer of the fluidized bed is controlled at 40-50°C; and / or, in step (c), the temperature of the particle bed layer of the fluidized bed is controlled at 35-45°C.

10. The preparation process according to claim 6, characterized in that: In step (a), the granulation is carried out using a double-roll extrusion granulator to control the average particle size of the particles to be 2.0 to 4.0 mm; and / or, after step (c), the preparation process further includes the steps of low-temperature air drying and maturation of the coated fertilizer particles.