Soil conditioner for continuous cropping obstacles of gastrodia elata and preparation method of soil conditioner

Abstract

The invention relates to the technical field of gastrodia elata planting, in particular to a soil amendment for continuous cropping obstacles of gastrodia elata and a preparation method, and the soil amendment comprises pH response type nano microspheres, enzyme response type nano microspheres, a humified organic matrix, a microelement chelating agent and water-absorbing and water-retaining resin. Through the synergistic effect of the double-response type nano-microsphere system, the modifier can dynamically release functional molecules according to the soil environment, promote symbiosis of armillaria mellea and inhibit soil-borne pathogenic bacteria. The preparation method comprises the steps of nano microsphere preparation, mixing granulation, drying and the like. According to the application, the problems of short effect, lack of specificity and the like in the prior art are solved, the yield of the gastrodia elata and the ecological quality of soil are remarkably improved, and a breakthrough solution is provided for continuous cropping obstacle prevention and treatment of the gastrodia elata.

Description

Technical Field

[0001] This invention belongs to the field of Gastrodia elata cultivation technology, specifically relating to a soil conditioner and its preparation method for overcoming continuous cropping obstacles in Gastrodia elata. Background Technology

[0002] Gastrodia elata is an important and precious traditional Chinese medicine. Its growth depends on an obligate symbiotic relationship with Armillaria mellea. However, after 2-3 years of continuous planting, the accumulation of autotoxic substances in the soil (such as p-hydroxybenzoic acid and vanillic acid), the proliferation of soil-borne pathogens (such as Fusarium and Fusarium solani), and the decline in the activity of Armillaria mellea all contribute to the phenomenon of "continuous cropping obstacle," which manifests as rotting of Gastrodia elata tubers, sharp reduction in yield, or even crop failure.

[0003] Currently, the main improvement measures for the continuous cropping obstacles of Gastrodia elata include: (1) crop rotation or fallow; (2) applying lime to adjust pH; and (3) adding bio-organic fertilizer or microbial agents. However, these methods have certain limitations: the crop rotation cycle is long and the land utilization rate is low; lime can only adjust pH in the short term and cannot solve the microbial imbalance; and existing bio-inoculants have a low colonization rate in continuously cropped soils and lack a specific growth-promoting effect on Armillaria mellea.

[0004] Recent studies have found that in the symbiotic relationship between Gastrodia elata and Armillaria mellea, phenolic substances secreted by Gastrodia elata can induce Armillaria mellea to form an infection structure, while Armillaria mellea establishes the symbiosis by secreting specific enzymes to degrade the cell wall of Gastrodia elata. Methylparaben has been identified as a key symbiotic signaling molecule. On the other hand, 3-phenyllactic acid, as a natural antimicrobial peptide precursor, has a strong inhibitory effect on Fusarium oxysporum and is non-toxic to Armillaria mellea. However, direct application of these small molecules suffers from problems such as easy adsorption by soil, rapid degradation, and lack of targeting, making long-term regulation difficult.

[0005] Furthermore, patent CN106613084A discloses a method for cultivating Gastrodia elata, including steps such as pre-culturing the inoculum, seed dressing, planting, and adding a protective layer. This method involves placing new wood around the inoculum and then applying multiple layers of superabsorbent polymer resin around the new wood to absorb water from the inoculum, preventing the growth of large amounts of mold on the inoculum. This method solves the problem in existing technologies where mold growth on the inoculum inhibits the growth of Armillaria mellea and results in low germination rates of Gastrodia elata seeds. However, this method does not address how to effectively deal with the accumulation of autotoxic substances in continuously cropped soil and the inhibition of soil-borne pathogens, and it fails to provide a continuously stable environment conducive to the growth of Armillaria mellea.

[0006] Patent CN108651252A discloses a method for cultivating Gastrodia elata, including the following steps: S1: A layer of soft sand is laid on the bottom plate of the cultivation box as a base layer. Branches are then placed on the base layer, and Armillaria mellea spores are placed on the branches. Sand is then covered as a culture layer. Next, Gastrodia elata mother plants are evenly placed on the culture layer and covered with sand as a planting layer. Finally, sand is laid on top of the planting layer as a covering layer. S2: A microcontroller controls the opening of the first inlet valve on the first water outlet pipe and the second inlet valve on the second water outlet pipe, and starts the water pump located at the connection between the first and second water outlet pipes, allowing water from the water tank connected to the first water outlet pipe to enter the cultivation box from the top. This invention solves the problem of insufficient utilization of Armillaria mellea in existing Gastrodia elata cultivation devices. However, this method mainly focuses on water management and the optimization of Armillaria mellea distribution, and fails to address the problem of autotoxic substances accumulation in continuously cropped soils. At the same time, it has limited inhibitory effect on soil-borne pathogens and has failed to form a systematic soil improvement program.

[0007] Neither of the two existing technical solutions mentioned above involves the preparation of soil conditioners for continuous cropping obstacles of Gastrodia elata and their long-term regulatory mechanisms, making it difficult to comprehensively solve the problem of continuous cropping obstacles of Gastrodia elata. Summary of the Invention

[0008] To overcome the problems in the prior art, the present invention provides a soil conditioner and preparation method for continuous cropping obstacles of Gastrodia elata. It aims to solve the shortcomings of the existing technology in the prevention and control of continuous cropping obstacles of Gastrodia elata by combining multiple components such as humified organic matrix, trace element chelating agent and water-absorbing and water-retaining resin through the synergistic effect of dual-response nanosphere system.

[0009] In a first aspect, this application provides a soil conditioner for overcoming continuous cropping obstacles of Gastrodia elata, comprising the following components by mass percentage: pH-responsive nanospheres: 20% to 30%, wherein the pH-responsive nanospheres are loaded with methylparaben; enzyme-responsive nanospheres: 15% to 25%, wherein the enzyme-responsive nanospheres are loaded with 3-phenyllactic acid; humified organic matrix: 40% to 55%; trace element chelating agent: 2% to 5%; water-absorbing and water-retaining resin: 1% to 3%.

[0010] According to this application, pH-responsive nanospheres are prepared by ionic crosslinking of chitosan and sodium alginate, with a particle size of 200 to 500 nanometers. These nanospheres swell and release loaded molecules at pH values ​​less than or equal to 5.5. The nanospheres utilize the electrostatic interaction between chitosan and sodium alginate to form a stable network structure. When the local soil pH drops below 5.5, the internal network structure of the nanospheres begins to expand, thereby releasing methylparaben. Methylparaben acts as a key symbiotic signaling molecule, promoting the formation of Armillaria mellea infection structures and strengthening its symbiotic relationship with Gastrodia elata.

[0011] According to this application, enzyme-responsive nanospheres are prepared by cross-linking humic acid and gelatin via transglutaminase. The particle size is 300 to 600 nanometers, and the protease concentration (defined as the amount of enzyme required to hydrolyze casein to produce 1 μmol of tyrosine per gram of soil) is ≥5 U / g, as detected by the Folin-phenol colorimetric method. At this concentration, degradation occurs, releasing the loaded molecules. Humic acid and gelatin form a stable three-dimensional network structure through transglutaminase cross-linking. When soil-borne pathogens actively secrete proteases and the protease concentration in the soil reaches ≥5 U / g, the network structure of the microspheres is degraded by the protease, thereby releasing 3-phenyllactic acid. 3-phenyllactic acid has an inhibitory effect on soil-borne pathogens such as Fusarium oxysporum, while having no toxic effect on Armillaria mellea.

[0012] According to this application, the humified organic substrate is prepared by composting corn stalks and waste Armillaria mellea in a 3:1 mass ratio. The composting temperature is controlled at 55 to 65 degrees Celsius for 15 days, resulting in a humification degree of over 40%. After composting, the organic matter in the corn stalks and waste Armillaria mellea decomposes into humic acids, which improve soil aggregate structure, increase soil aeration and water retention, and provide a suitable environment for the growth of Armillaria mellea.

[0013] According to this application, the trace element chelating agent is a mixture of EDTA-Fe and EDTA-Zn in a mass ratio of 2:1. EDTA-Fe and EDTA-Zn exist in a chelated form, effectively preventing trace elements from being fixed in the soil, improving their bioavailability, and meeting the nutritional needs of Gastrodia elata and Armillaria mellea.

[0014] According to this application, the water-absorbing and water-retaining resin is cross-linked sodium polyacrylate with a water absorption ratio of 300 g / g to 500 g / g. Cross-linked sodium polyacrylate possesses high water absorption and retention properties, enabling it to form micro-reservoirs in the soil, reducing water evaporation, maintaining soil moisture, and providing stable moisture conditions for the growth of Gastrodia elata and Armillaria mellea.

[0015] Secondly, this application provides a method for preparing the above-mentioned soil conditioner, comprising the following steps: S10: preparing pH-responsive nanospheres, dissolving chitosan in 1% acetic acid solution, adding ethanol solution of methylparaben, ultrasonically emulsifying, then adding sodium alginate solution, stirring and crosslinking for 2 hours, centrifuging, washing, and freeze-drying to obtain pH-responsive nanospheres; S20: preparing enzyme-responsive nanospheres, dissolving 3 g of gelatin in 50 mL of 40°C warm water, adding 50 mL of aqueous solution containing 0.15 g of 3-phenyllactic acid, then suspending 2 g of humic acid powder that has passed through a 200-mesh sieve in 50 mL of water to prepare a humic acid suspension and adding it, adjusting the pH to 7.0, adding transglutaminase, reacting at 37°C for 4 hours, dialysis, and freeze-drying to obtain enzyme-responsive nanospheres; S30: Mixing and granulation. The microspheres obtained in steps S10 and S20 are mixed in a mass ratio of 25:20. Humic organic matrix, trace element chelating agent and water-absorbing and water-retaining resin are added. After thorough mixing, the mixture is extruded and granulated. The particle size is controlled between 2 and 5 mm. The mixture is dried at 60 degrees Celsius until the moisture content is less than or equal to 10% to obtain the finished product.

[0016] According to this application, in step S10, the amount of chitosan used is 2 grams per 100 ml of 1% acetic acid solution, and the amount of methylparaben used is 0.2 grams per 10 ml of ethanol solution. Chitosan dissolves in the dilute acetic acid solution to form a uniform dispersion system. Methylparaben is introduced into the system through the ethanol solution. After ultrasonic emulsification, a stable nanoscale emulsion is formed. Upon dropwise addition of sodium alginate solution, ionic cross-linking occurs, forming responsive nanospheres.

[0017] According to this application, in step S20, the amount of gelatin used is 3 grams per 50 ml of water at 40 degrees Celsius, the amount of 3-phenyllactic acid used is 0.15 grams per 50 ml of water, the amount of humic acid used is 2 grams per 50 ml of water, and the amount of transglutaminase used is 0.5% of the total mass of the reaction system. Gelatin is dissolved in warm water to form a homogeneous solution. 3-phenyllactic acid and humic acid are introduced into the system through physical mixing. After adjusting the pH to 7.0, transglutaminase is added, and stable enzyme-responsive nanospheres are formed through an enzymatic cross-linking reaction.

[0018] According to this application, in step S30, the humified organic substrate is prepared by composting corn stalks and waste Armillaria mellea fungal material at a mass ratio of 3:1; the trace element chelating agent is prepared by mixing EDTA-Fe and EDTA-Zn at a mass ratio of 2:1; and the water-absorbing and water-retaining resin is cross-linked sodium polyacrylate with a water absorption ratio of 300 g / g to 500 g / g. After the components are mixed according to the set proportions, they are granulated by extrusion to form uniform particles. After drying, the moisture content is controlled below 10% to ensure product stability.

[0019] The beneficial effects of this invention are: 1. This invention achieves effective regulation of the problem of continuous cropping obstacles in Gastrodia elata through the synergistic effect of a dual microsphere system. pH-responsive and enzyme-responsive nanospheres are designed specifically for Armillaria mellea and soil-borne pathogens, respectively, and can release functional molecules according to dynamic changes in the soil environment. Humic organic matrix provides a long-term supply of organic nutrients, trace element chelators ensure the nutritional needs of Gastrodia elata and Armillaria mellea, and water-absorbing and water-retaining resin maintains soil moisture balance. When the metabolic activity of Armillaria mellea increases, causing the local soil pH to drop below 5.5, the pH-responsive nanospheres swell and release methylparaben. This substance specifically activates the infection structure of Armillaria mellea, strengthening its symbiotic relationship with Gastrodia elata. When soil-borne pathogens actively secrete proteases, and the protease concentration in the soil reaches more than 5 units per gram of soil, the enzyme-responsive nanospheres degrade, releasing 3-phenyllactic acid, inhibiting the reproduction of pathogens such as Fusarium oxysporum, and avoiding accidental damage to beneficial bacteria.

[0020] 2. This invention uses natural polymer materials as carriers, including chitosan, sodium alginate, humic acid, and gelatin. These materials all possess good biocompatibility and biodegradability, and can completely decompose into harmless products, without causing secondary pollution to the soil ecosystem. Furthermore, through microsphere encapsulation technology, the half-life of methylparaben and 3-phenyllactic acid is extended by 3 to 5 times, and the release effect of the functional molecules can last for a planting season.

[0021] In summary, this invention, by constructing a dual-function intelligent sustained-release system and combining multiple components such as humified organic matrix, trace element chelating agent, and water-absorbing and water-retaining resin, solves the problems of short-lived effects, lack of specificity, and inability to dynamically regulate the effects of existing modifiers, providing a breakthrough solution for the prevention and control of continuous cropping obstacles in Gastrodia elata. Detailed Implementation

[0022] To make the objectives, technical solutions, and beneficial effects of the present invention clearer, the preferred embodiments of the present invention will be described in detail below to facilitate understanding by those skilled in the art.

[0023] This application provides a soil conditioner for continuous cropping obstacles of Gastrodia elata and its preparation method. It aims to overcome the shortcomings of existing technologies in the prevention and control of continuous cropping obstacles of Gastrodia elata by combining multiple components such as humified organic matrix, trace element chelating agent and water-absorbing and water-retaining resin through the synergistic effect of dual-response nanosphere system.

[0024] In one aspect, this application provides a soil conditioner for the continuous cropping obstacle of Gastrodia elata, comprising the following components in mass percentage: 20% to 30% pH-responsive nanospheres, 15% to 25% enzyme-responsive nanospheres, 40% to 55% humified organic matrix, 2% to 5% trace element chelating agent, and 1% to 3% water-absorbing and water-retaining resin.

[0025] According to this application, pH-responsive nanospheres are prepared by ionic crosslinking of chitosan and sodium alginate, with a particle size of 200 to 500 nanometers. The loading molecule is methylparaben. When the local pH of the soil drops below 5.5, the internal network structure of the microspheres begins to expand and release the loading molecule. Chitosan is dissolved in a 1% acetic acid solution, and after adding an ethanol solution of methylparaben, it is ultrasonically emulsified and dropwise added to a sodium alginate solution. The mixture is stirred and crosslinked for 2 hours, then centrifuged, washed, and freeze-dried to obtain the pH-responsive nanospheres.

[0026] According to this application, enzyme-responsive nanospheres are prepared by cross-linking humic acid and gelatin with transglutaminase, with a particle size of 300 to 600 nanometers. The loading molecule is 3-phenyllactic acid. When the concentration of protease secreted by soil-borne pathogens reaches more than 5 units per gram of soil, the network structure of the microspheres is degraded, releasing the loading molecule. Gelatin is dissolved in warm water, and an aqueous solution of 3-phenyllactic acid and a humic acid suspension are added. After adjusting the pH to 7.0, transglutaminase is added, and the reaction is carried out at 37 degrees Celsius for 4 hours. After dialysis, the nanospheres are freeze-dried to obtain the enzyme-responsive nanospheres.

[0027] According to this application, the humified organic substrate is prepared by composting corn stalks and waste Armillaria mellea inoculum at a mass ratio of 3:1. The composting temperature is controlled at 55 to 65 degrees Celsius for 15 days, and the degree of humification (calculated as the proportion of humic acid to organic carbon) reaches more than 40%, as tested according to GB / T 35107-2017 "Determination Method for Humic Degree of Compost". The trace element chelating agent is a mixture of EDTA-Fe and EDTA-Zn at a mass ratio of 2:1. The water-absorbing and water-retaining resin is cross-linked sodium polyacrylate with a water absorption ratio of 300 g / g to 500 g / g.

[0028] Secondly, this application provides a method for preparing the above-mentioned soil conditioner, comprising the following steps: S10: preparing pH-responsive nanospheres; S20: preparing enzyme-responsive nanospheres; S30: mixing and granulating.

[0029] In step S10, chitosan is dissolved in a 1% acetic acid solution, with 2 g of chitosan added per 100 mL of solution. An ethanol solution of methylparaben is also added, with 0.2 g of methylparaben added per 10 mL of ethanol solution. After ultrasonic emulsification (300-500 W, 20 kHz, 10-15 minutes), a 1% sodium alginate solution is added dropwise. The mixture is stirred and crosslinked for 2 hours. After centrifugation (8000 rpm, 10 minutes), washing (3 times with water), and freeze-drying, pH-responsive nanospheres are obtained.

[0030] In step S20, gelatin was dissolved in 40°C warm water. 3 grams of gelatin were added to every 50 ml of water, along with an aqueous solution of 3-phenyllactic acid and 0.15 grams of 3-phenyllactic acid per 50 ml of water. Then, 2 grams of humic acid powder (passed through a 200-mesh sieve) was suspended in 50 ml of water to prepare a humic acid suspension, which was then added. After adjusting the pH to 7.0, transglutaminase was added, with 0.5% of the total mass of the reaction system being the amount of transglutaminase. The reaction was carried out at 37°C for 4 hours, followed by dialyzing for 48 hours (using a cellulose membrane with a molecular weight cutoff of 8 kDa, 0.01 M phosphate buffer, pH 7.0), and then freeze-dried to obtain enzyme-responsive nanospheres.

[0031] In step S30, the microspheres obtained in steps S10 and S20 are mixed in a mass ratio of 25:20, and a humified organic matrix, a trace element chelating agent, and a water-absorbing and water-retaining resin are added. After thorough mixing, the mixture is extruded and granulated. The particle size is controlled between 2 and 5 mm, and the mixture is dried at 60 degrees Celsius until the moisture content is less than or equal to 10% to obtain the finished product.

[0032] The soil conditioner provided in this application offers a breakthrough solution to the problem of continuous cropping obstacles in Gastrodia elata through multi-dimensional regulation. pH-responsive and enzyme-responsive nanospheres are designed specifically for Armillaria mellea and soil-borne pathogens, respectively, and can release functional molecules according to dynamic changes in the soil environment. The humified organic matrix provides a long-lasting supply of organic nutrients, the micronutrient chelator ensures the nutritional needs of Gastrodia elata and Armillaria mellea, and the water-absorbing and water-retaining resin maintains soil moisture balance.

[0033] To verify the technical solution of this application, experimental and control groups were designed for comparative analysis. The experimental group received the soil conditioner of this application, while the control groups received ordinary organic fertilizer without nanospheres, traditional methods of adjusting pH with lime only, and a blank control without any conditioner. The experimental results are shown in the table below: Group Gastrodia elata tuber yield (kg / mu) Soil Armillaria mellea activity index Soil Fusarium count (CFU / g) Soil pH experimental group 850 0.85 120 5.8 Control group 1 620 0.55 350 6.2 Control group 2 580 0.45 420 6.5 Control group 3 400 0.30 500 6.8 The experimental data show that the experimental group that applied the soil conditioner of this application was significantly better than other control groups in terms of Gastrodia elata tuber yield, Armillaria mellea activity index and Fusarium moniliforme number, indicating that the technical solution of this application can effectively alleviate the problem of continuous cropping obstacles of Gastrodia elata.

[0034] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0035] Example 1: Preparation of pH-responsive nanospheres: 2 g of chitosan was dissolved in 100 mL of 1% acetic acid solution. An ethanol solution of methylparaben was added, with 0.2 g of methylparaben added per 10 mL of ethanol solution. After ultrasonic emulsification (300-500 W, 20 kHz, 10-15 min), a 1% sodium alginate solution was added dropwise. The mixture was stirred and crosslinked for 2 hours. After centrifugation (8000 rpm, 10 min), washing (3 times with water), and freeze-drying, pH-responsive nanospheres were obtained. Preparation of enzyme-responsive nanospheres: 3 g of gelatin was dissolved in 50 mL of 40°C warm water. An aqueous solution of 3-phenyllactic acid was added, with 0.15 g of 3-phenyllactic acid added per 50 mL of water. Then, 2 g of humic acid powder (passed through a 200-mesh sieve) was suspended in 50 mL of water to prepare a humic acid suspension, which was then added. After adjusting the pH to 7.0, 0.025 g of transglutaminase was added, and the reaction was carried out at 37°C for 4 hours. The mixture was then dialyzed for 48 hours (using a cellulose membrane with a molecular weight cutoff of 8 kDa, 0.01 M phosphate buffer, pH 7.0) and freeze-dried to obtain enzyme-responsive nanospheres. For granulation, pH-responsive and enzyme-responsive nanospheres were mixed at a mass ratio of 25:20, and a humified organic matrix, trace element chelating agent, and water-absorbing resin were added. After thorough mixing, the mixture was extruded and granulated. The particle size was controlled between 2 and 5 mm, and the mixture was dried at 60°C until the moisture content was less than or equal to 10% to obtain the final product.

[0036] Example 2: Compared with Example 1, the mass ratio of pH-responsive nanospheres and enzyme-responsive nanospheres was adjusted to 30:15, and the remaining steps were the same.

[0037] Example 3: Compared with Example 1, the composting temperature of the humified organic substrate was controlled at 60 to 65 degrees Celsius, and the other steps were the same.

[0038] Example 4: Compared with Example 1, the mass ratio of EDTA-Fe to EDTA-Zn in the trace element chelating agent was adjusted to 3:1, and the other steps were the same.

[0039] Comparative Example 1: No pH-responsive nanospheres or enzyme-responsive nanospheres were added; the remaining steps were the same as in Example 1.

[0040] Comparative Example 2: Only lime was applied to adjust the pH; the remaining steps were the same as in Example 1.

[0041] Comparative Example 3: No modifier was applied, and the remaining steps were the same as in Example 1.

[0042] The soil conditioners obtained from the above examples and comparative examples were applied to a Gastrodia elata cultivation experiment, and the relevant data are shown in the table below: Group Gastrodia elata tuber yield (kg / mu) Soil Armillaria mellea activity index Soil Fusarium count (CFU / g) Soil pH Example 1 850 0.85 120 5.8 Example 2 830 0.83 130 5.9 Example 3 840 0.84 125 5.7 Example 4 820 0.82 140 5.8 Comparative Example 1 620 0.55 350 6.2 Comparative Example 2 580 0.45 420 6.5 Comparative Example 3 400 0.30 500 6.8 According to the data in the table, the soil conditioner obtained in this application has a higher yield of Gastrodia elata tubers, a higher Armillaria mellea activity index, and a lower Fusarium count compared to the comparative examples, indicating that the technical solution of this application can effectively alleviate the problem of continuous cropping obstacles of Gastrodia elata. Comparative Example 1 did not add nanospheres, resulting in a significantly reduced effect; Comparative Example 2 only adjusted the pH, failing to comprehensively improve the soil environment; Comparative Example 3 did not apply any conditioner, resulting in the worst effect.

[0043] In summary, this invention, by constructing a dual-function intelligent sustained-release system and combining multiple components such as humified organic matrix, trace element chelating agent, and water-absorbing and water-retaining resin, solves the problems of short-lived effects, lack of specificity, and inability to dynamically regulate the effects of existing modifiers, providing a breakthrough solution for the prevention and control of continuous cropping obstacles in Gastrodia elata.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A soil amendment for ginseng continuous cropping obstacles, characterized by, The following components are included in the composition by mass percentage: pH-responsive nanospheres: 20% to 30%, prepared by ionic cross-linking of chitosan and sodium alginate, with a particle size of 200 nm to 500 nm, swelling and releasing the loaded methyl paraben when the pH is less than or equal to 5.5; enzyme-responsive nanospheres: 15% to 25%, prepared by transglutaminase cross-linking of humic acid and gelatin, with a particle size of 300 nm to 600 nm, degrading and releasing the loaded 3-phenyllactic acid when the protease concentration is greater than or equal to 5 units per gram of soil; humified organic matrix: 40% to 55%; trace element chelator: 2% to 5%; water-absorbing and water-retaining resin: 1% to 3%.

2. The soil amendment of claim 1, wherein, The humified organic matrix is prepared by composting corn straw and discarded Armillaria mellea material at a mass ratio of 3:1, with the composting temperature controlled at 55°C to 65°C for 15 days, and the humification degree reaching more than 40%.

3. The soil amendment of claim 1, wherein, The trace element chelator is a mixture of EDTA-Fe and EDTA-Zn, with a mass ratio of 2:

1.

4. The soil amendment of claim 1, wherein, The water-absorbing and water-retaining resin is cross-linked sodium polyacrylate, with a water absorption ratio of 300 g / g to 500 g / g.

5. A method for preparing the soil amendment according to any one of claims 1 to 4, characterized in that, The following steps are included: S10: Prepare pH-responsive nanospheres by dissolving chitosan in 1% acetic acid solution, adding methyl paraben in ethanol solution, ultrasonic emulsification, then dropping into sodium alginate solution, stirring and cross-linking for 2 hours, centrifugal separation, washing, and freeze-drying to obtain pH-responsive nanospheres; S20: Prepare enzyme-responsive nanospheres by dissolving 3 g of gelatin in 50 mL of 40°C warm water, adding 50 mL of water containing 0.15 g of 3-phenyllactic acid, then suspending 2 g of humic acid powder sieved to 200 mesh in 50 mL of water to prepare a humic acid suspension and adding it, adjusting the pH to 7.0, adding transglutaminase, and reacting at 37°C for 4 hours, then dialyzing and freeze-drying to obtain enzyme-responsive nanospheres; S30: Mix and granulate the nanospheres obtained in steps S10 and S20 at a mass ratio of 25:20, add the humified organic matrix, trace element chelator, and water-absorbing and water-retaining resin, mix thoroughly, then extrude and granulate, with the particle size controlled between 2 mm and 5 mm, and dry at 60°C until the water content is less than or equal to 10%, to obtain the finished product.

6. The method of claim 5, wherein, In step S10, the amount of chitosan used is 2 g per 100 mL of 1% acetic acid solution, and the amount of methyl paraben used is 0.2 g per 10 mL of ethanol solution.

7. The method of claim 5, wherein, In step S20, the amount of gelatin used is 3 g per 50 mL of 40°C water, the amount of 3-phenyllactic acid used is 0.15 g per 50 mL of water, the amount of humic acid used is 2 g per 50 mL of water, and the amount of transglutaminase used is 0.5% of the total mass of the reaction system.

8. The method of claim 5, wherein, In the step S30, the humic organic substrate is prepared by composting corn stalks and waste Armillaria mellea materials at a mass ratio of 3:1, the trace element chelating agent is prepared by mixing EDTA-Fe and EDTA-Zn at a mass ratio of 2:1, and the water-absorbing and water-retaining resin is a cross-linked sodium polyacrylate with a water-absorbing capacity of 300-500 g / g.