Soil moisture and fertilizer retention type conditioner based on nanotechnology and preparation method thereof

Abstract

The invention discloses a soil moisture and fertilizer retention type conditioner based on a nanotechnology and a preparation method thereof, and relates to the technical field of agricultural soil remediation. The conditioner comprises an amphiphilic nano composite carrier, a nano mineralization material, nano enzyme and stress-tolerant functional microorganisms, a three-dimensional porous network structure is formed through directional assembly of the amphiphilic nano composite carrier, and uniform loading and stable dispersion of all functional components are achieved. The nano mineralization material is chemically bonded with the carrier through in-situ deposition, and heavy metal fixation is enhanced; the nano-enzyme is directionally anchored in a hydrophobic region of the carrier, so that the stress resistance of crops is improved; stress-tolerant functional microorganisms are fixed through adsorption-embedding compounding, and keep activity and promote soil remediation under the protection of the carrier. All the technical means cooperate to form a closed-loop system, salt removal, heavy metal fixation, water retention, efficient nutrient utilization and crop stress resistance enhancement are synchronously achieved, and an integrated solution is provided for composite degraded soil improvement.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of agricultural soil remediation, in particular to a soil water and fertilizer retention type conditioner based on nanotechnology and a preparation method thereof. BACKGROUND

[0002] The northern arid and semiarid regions are important grain production areas in China, but the soil in the regions is generally seriously salinized, and the heavy metal content exceeds the standard, and the problems of seasonal drought and compound degradation coexist, the soil structure is damaged, the water and fertilizer retention capacity is weak, and the crop growth adversity is prominent, which directly leads to reduced grain yield and increased risk of agricultural product quality and safety, and becomes a key bottleneck restricting the sustainable development of agriculture in the region. The treatment of such compound degraded soil needs to simultaneously solve the problems of salt removal, heavy metal fixation, water retention, nutrient efficient utilization and crop stress resistance enhancement, and the treatment difficulty is much higher than that of single degraded soil.

[0003] Existing soil conditioning technologies are mostly designed for single degradation problem, such as nano-mineralized materials focusing only on heavy metal fixation, conventional water retention agents only focusing on water retention, and microbial agents only focusing on fertilizer improvement, and there is a lack of integrated solutions with multiple functions. At the same time, in the existing technology, the nano materials are easy to agglomerate in the soil, the microorganisms are easy to lose activity in extreme environment, and the action period of functional components is short, so that when each technology is used alone or simply stacked, the simultaneous treatment of compound degraded soil cannot be realized, and the improvement effect decays quickly and the effective period is short, which cannot meet the comprehensive demand of actual agricultural production for soil improvement.

[0004] Therefore, the application is provided. SUMMARY

[0005] The application aims to provide a soil water and fertilizer retention type conditioner based on nanotechnology and a preparation method thereof, to solve the problems in the background.

[0006] To solve the above technical problems, the soil water and fertilizer retention type conditioner based on nanotechnology provided by the application comprises an amphiphilic nano composite carrier, a nano-mineralized material, a nano-enzyme and a stress-tolerant functional microorganism, and the components are in a mass percentage of 30%-50% of the amphiphilic nano composite carrier, 15%-25% of the nano-mineralized material, 5%-10% of the nano-enzyme and 20%-35% of the stress-tolerant functional microorganism; the amphiphilic nano composite carrier is formed into a three-dimensional porous network structure by directional assembly of modified nano montmorillonite and carbon nanotubes through grafting of hydrophilic carboxyl groups and hydrophobic polyethylene glycol segments, and the nano-mineralized material, the nano-enzyme and the stress-tolerant functional microorganism are loaded in the three-dimensional porous network structure; the conditioner realizes stable loading and uniform dispersion of the functional components through the directional assembly structure of the amphiphilic nano composite carrier, and simultaneously solves the problems of salinization, heavy metal pollution, drought and nutrient loss of compound degraded soil, and significantly improves the soil remediation effect and the crop stress resistance.

[0007] Further, the preparation process of the amphiphilic nanocomposite carrier is as follows: the nanomontmorillonite is modified by carboxyl group, the carbon nanotube is modified by polyethylene glycol segment grafting, the modified nanomontmorillonite and the modified carbon nanotube are mixed in a mass ratio of 2-3:1, and a three-dimensional porous network structure is formed by directional assembly under ultrasonic assistance; the preparation method further improves the dispersion stability and loading capacity of the amphiphilic carrier, provides a stable skeleton for the efficient action of subsequent functional components, and prolongs the effective period of the conditioner in the soil.

[0008] Further, the nanomineralized material is nanohydroxyapatite, which is combined with the carboxyl group on the surface of the amphiphilic nanocomposite carrier by in-situ deposition to be loaded in the pore inner wall of the three-dimensional porous network structure; the firm combination of nanohydroxyapatite and the carrier avoids its aggregation and loss, significantly improves the mineralization and fixation efficiency of heavy metal ions, and reduces the activity of heavy metals in the soil.

[0009] Further, the nanoenzyme is Zn-doped nanoprussian blue, which is anchored in the polyethylene glycol segment region of the amphiphilic nanocomposite carrier by hydrophobic interaction and has peroxidase-like activity; the directional loading of Zn-doped nanoprussian blue ensures its rapid removal of active oxygen generated by crops in adverse environments, synchronously regulates the ion balance of crops, and improves the salt and drought tolerance of crops.

[0010] Further, the stress-tolerant functional microorganism includes salt-tolerant nitrogen-fixing bacteria and desulfovibrio, which is fixed in the three-dimensional porous network structure of the amphiphilic nanocomposite carrier by adsorption-embedding composite method to form a stable bacteria group; the fixation method of the stress-tolerant functional microorganism improves its survival rate in saline-alkali and drought environments, the metabolic products promote the nanomineralization reaction and nutrient transformation, and the synergistic improvement of soil fertility and remediation effect is realized.

[0011] Further, the components are as follows in terms of mass percentage: the amphiphilic nanocomposite carrier accounts for 35%-45%, the nanohydroxyapatite accounts for 18%-22%, the Zn-doped nanoprussian blue accounts for 6%-8%, and the stress-tolerant functional microorganism accounts for 25%-30%; the component allocation ratio further optimizes the synergistic action efficiency of each functional component, significantly improves the soil water and fertilizer retention capacity, pollution remediation effect and crop stress resistance, and realizes efficient improvement of the compound degraded soil.

[0012] The preparation method of the soil water and fertilizer retention type conditioner based on nanotechnology comprises the following steps: first step, preparing an amphiphilic nanocomposite carrier; second step, depositing and loading nanomineralized materials in situ on the amphiphilic nanocomposite carrier; third step, anchoring and loading nanoenzymes on the amphiphilic nanocomposite carrier; fourth step, fixing and embedding the stress-tolerant functional microorganisms on the amphiphilic nanocomposite carrier by the adsorption-embedding composite method, and uniformly mixing to obtain the conditioner; the directional fixation of each functional component is realized through step-by-step loading, the conditioner has stable structure and efficient synergistic effect, the preparation process is simple and controllable, and the conditioner is suitable for large-scale production.

[0013] Further, in the first step, after the carboxyl-modified nanomontmorillonite is mixed with the polyethylene glycol segment grafted carbon nanotube, the ultrasonic power is medium-high power, the ultrasonic time is a preset length of time, and the assembly temperature is controlled at room temperature to 40 DEG C; the parameter control further improves the integrity of the three-dimensional network structure and the uniformity of the pores of the amphiphilic nanocomposite carrier, and enhances the loading capacity and dispersion effect of the carrier on the functional components.

[0014] Further, in the second step, the reaction temperature of in-situ deposition is 50 DEG C to 70 DEG C, and the reaction time is a preset length of time; in the fourth step, the pH value of the adsorption-embedding composite process is controlled at 6.0 to 7.0; the process parameter optimization further improves the combination firmness of the nanomineralized material and the carrier and the fixation stability of the microorganism, ensures the efficient play of each function of the conditioner, and improves the product qualification rate.

[0015] Compared with the prior art, the beneficial effects of the present application are:

[0016] 1、The present application realizes the synchronous and efficient treatment of multiple problems such as composite degraded soil salinization, heavy metal pollution and drought stress through the integrated design of directional assembly of the amphiphilic nanocomposite carrier, nanomineralization-microorganism synergy and nanoenzyme-water and fertilizer retention synergy, which is significantly superior to the existing single-function conditioning technology. The amphiphilic nanocomposite carrier forms a stable three-dimensional porous network structure through the precise grafting of hydrophilic carboxyl and hydrophobic polyethylene glycol segments and directional assembly assisted by ultrasonic, effectively solves the agglomeration problem of nanomaterials in soil, and realizes the uniform loading and stable dispersion of different polar functional components, laying a solid foundation for the synergistic effect of each function.

[0017] 2. Nanomaterials form chemical bonds with the carrier through in-situ deposition, preventing the migration and loss of functional components and significantly improving the heavy metal fixation efficiency. Simultaneously, the porous structure of the carrier enriches heavy metal ions, accelerating the mineralization reaction. Nanoenzymes are directionally anchored in the hydrophobic regions of the carrier through hydrophobic interactions, achieving partitioned loading with the nanomaterials and avoiding functional interference. The protective effect of the carrier extends the activity cycle of the nanoenzymes, effectively scavenging reactive oxygen species generated under crop stress and significantly improving crop resistance. Stress-tolerant microorganisms are firmly locked within the carrier network through an adsorption-encapsulation composite fixation method. The moisture and nutrients provided by the carrier ensure the survival rate of microorganisms in extreme environments, while microbial metabolites promote the nanomineralization reaction and enhance the adsorption performance of the carrier, forming a virtuous cycle of carrier protection and microorganism strengthening of carrier function, effectively extending the duration of the conditioner's effect.

[0018] 3. The unique technical means are not simply superimposed, but form a closed-loop synergistic effect of pollution remediation, water retention, fertilizer retention, crop stress resistance and fertility enhancement. It not only solves multiple core problems of compound degraded soils at the same time, but also significantly improves soil structure, enhances soil fertility and crop growth performance. It effectively overcomes the defects of existing technologies such as single function, rapid effect decay and narrow range of application, and provides an efficient and stable integrated solution for the improvement of compound degraded soils, promoting sustainable agricultural development. Attached Figure Description

[0019] Figure 1 This is a flowchart of a soil water-retaining and fertilizer-retaining conditioner based on nanotechnology and its preparation method. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1 This invention provides a technical solution: a soil water-retaining and fertilizer-retaining conditioner based on nanotechnology and its preparation method. This specific embodiment addresses the need for soil improvement in arid and semi-arid areas of northern China, where soil is severely salinized, contains excessive heavy metals, and is accompanied by seasonal drought. It elaborates in detail the preparation and application process of the conditioner based on amphiphilic nanocomposite carrier directional assembly technology, nanomineralization-microbial synergistic repair technology, and nanoenzyme-water-retaining and fertilizer-retaining composite synergistic system.

[0022] Example 1:

[0023] Step one: preparation of amphiphilic nanocomposite carrier: the nanomaterials in the degraded soil are easy to agglomerate, resulting in uneven dispersion of functional components and attenuation of action efficiency. Single hydrophilic or hydrophobic carrier cannot simultaneously adsorb water-soluble salts, nutrients and fat-soluble substances in the soil, making it difficult to achieve the coordinated solution of multiple problems. Based on the principle of surface modification and directional assembly of nanomaterials, an amphiphilic carrier is constructed by grafting hydrophilic and hydrophobic groups, which can realize the stable loading and uniform dispersion of functional components by using its three-dimensional porous structure, and provide habitat sites for microorganisms. This is the core design to solve the problems of nanomaterial agglomeration and single function. The specific implementation process is as follows:

[0024] High-purity and high-specific-surface-area nanomontmorillonite and carbon nanotubes are selected as raw materials. The nanomontmorillonite is first modified by carboxylation: the nanomontmorillonite is added to a modifier solution and heated to a preset temperature under stirring, and the reaction is carried out for a preset time to graft a large number of carboxyl groups on the surface of the nanomontmorillonite, thereby enhancing its hydrophilicity and reactivity. At the same time, the carbon nanotubes are modified by grafting polyethylene glycol segments: the carbon nanotubes are dispersed in a solvent, and polyethylene glycol derivatives are added, and the reaction is carried out for a preset time under the action of a catalyst to graft hydrophobic polyethylene glycol segments on the surface of the carbon nanotubes, thereby improving their compatibility with fat-soluble components.

[0025] The carboxyl-modified nanomontmorillonite and the polyethylene glycol segment-grafted carbon nanotubes are mixed in a mass ratio of 2.5:1, deionized water is added to form a suspension, and a medium-high-power ultrasonic treatment is carried out for a preset time. The directional assembly of the two modified nanomaterials is promoted by the dispersion effect and intermolecular forces (hydrogen bonds and hydrophobic interactions) of ultrasonic treatment, forming a three-dimensional porous network structure. Subsequently, after drying and crushing, an amphiphilic nanocomposite carrier is obtained.

[0026] The three-dimensional porous network structure of the amphiphilic nanocomposite carrier prepared in this step is formed by directional assembly, which significantly improves the dispersion stability compared to single modified nanomaterials or physically mixed carriers in the prior art, effectively avoids agglomeration in the soil, and significantly improves the loading capacity. The prior art discloses a composite carrier of nanomontmorillonite and carbon nanotubes, but only realizes physical mixing without amphiphilic modification and directional assembly, which has the defects of poor dispersion and limited loading capacity. The unique technical means is to precisely graft hydrophilic carboxyl groups and hydrophobic polyethylene glycol segments, combined with ultrasonic-assisted directional assembly, to construct a three-dimensional network with both hydrophilic and hydrophobic properties, which can simultaneously adsorb different polar substances and provide a stable skeleton for the subsequent loading of functional components, thereby prolonging the persistence of the conditioner in the soil.

[0027] Step Two: Loading Nanomaterials for Mineralization: Heavy metal ions in degraded soils are prone to migration. Existing nanomaterials for mineralization are mostly applied alone, resulting in easy loss and low reaction efficiency. Based on the principles of chemical bonding and in-situ deposition, nanomaterials for mineralization are loaded onto the surface of an amphiphilic carrier. The carrier's adsorption capacity can enrich heavy metal ions, increasing the local concentration of the mineralization reaction. Simultaneously, chemical bonding enhances the material's stability, preventing migration and loss in the soil, thus achieving a synergistic effect between efficient heavy metal fixation and the carrier's function. The specific process is as follows:

[0028] Nano-hydroxyapatite was selected as the nano-mineralization material due to its strong binding ability with heavy metal ions, making it suitable for the fixation of heavy metals such as Cd and Pb. The amphiphilic nanocomposite support prepared in step one was added to deionized water and stirred to form a uniform suspension. The nano-hydroxyapatite dispersion was then slowly added dropwise, with the reaction temperature controlled between 50℃ and 70℃ and the reaction time set for a predetermined duration. Stable chemical bonds were formed through the chemical reaction between the carboxyl groups on the surface of the amphiphilic support and the hydroxyl groups on the surface of the nano-hydroxyapatite, allowing the nano-hydroxyapatite to be deposited in situ and firmly loaded onto the pore walls of the three-dimensional porous network of the support. After the reaction, the mixture was filtered, washed, and dried to obtain the composite support loaded with the nano-mineralization material.

[0029] This loading method enables nano-hydroxyapatite to form a strong bond with the carrier, significantly reducing the loss rate and greatly improving the heavy metal fixation efficiency compared to the physical mixing loading method in existing technologies. Existing technologies disclose the use of nano-hydroxyapatite for soil heavy metal remediation, but without binding to an amphiphilic carrier, they suffer from problems such as easy aggregation and short action period. The unique technical approach lies in forming a chemical bond between the nano-mineralized material and the carrier through in-situ deposition, rather than simple physical adsorption. This not only improves the stability of the material but also allows the porous structure of the carrier to enrich heavy metal ions, accelerating the mineralization reaction and significantly reducing the activity of heavy metals in the soil, while avoiding damage to the soil's pore structure by the mineralized material.

[0030] Step 3: Loading Nanozymes: Crops in degraded soils are susceptible to excessive reactive oxygen species (ROS) due to salinity and drought stress, leading to stunted growth. Existing conditioners lack targeted stress-resistance mechanisms, and nanozymes, when applied alone, have short action distances and are easily inactivated. Based on the principles of enzymatic reaction and carrier anchoring, nanozymes with peroxidase-like activity are loaded into the hydrophobic region of an amphiphilic carrier. The protective effect of the carrier can extend the activity cycle of the nanozymes, while the water retention function of the carrier ensures that the nanozymes can still function efficiently in arid environments, achieving a synergistic effect of stress resistance and water retention. The specific implementation process is as follows:

[0031] Zn-doped Prussian blue nanoparticles were selected as the nanozyme, exhibiting high peroxidase-like activity and efficient removal of reactive oxygen species produced by crops. Simultaneously, Zn can regulate the ion balance of crops. The composite carrier loaded with nano-mineralized materials obtained in step two was added to the dispersion and stirred until homogeneous. Then, Zn-doped Prussian blue nanoparticle powder was slowly added, and the reaction was carried out at room temperature for a preset time. Utilizing the hydrophobic interaction between Zn-doped Prussian blue nanoparticles and the polyethylene glycol segments on the carrier surface, the nanozyme was anchored in the hydrophobic region of the carrier, avoiding interaction with the hydrophilic mineralized material and ensuring that both functional components functioned effectively. After the reaction, the nano-mineralized material and nanozyme were obtained through drying.

[0032] This directional anchoring method ensures uniform distribution of nanozymes on the carrier surface. Compared to existing technologies that indiscriminately mix nanozymes with carriers, this significantly improves activity retention and results in more stable stress resistance. Existing technologies disclose the use of nanozymes for crop stress resistance, but without binding to amphiphilic carriers, they suffer from drawbacks such as short action cycles and high susceptibility to environmental influences. The unique technique utilizes the amphiphilic differences of the carrier to directionally anchor the nanozymes in hydrophobic regions, achieving partitioned loading with nanomineralized materials. This avoids interference between functional components, while the three-dimensional network structure of the carrier provides protection for the nanozymes, reducing the inhibition of their activity by saline-alkali and drought environments, rapidly scavenging reactive oxygen species within the crop, and enhancing the crop's salt and drought tolerance.

[0033] Step Four: Immobilizing Stress-Resistant Microorganisms: The extreme environments (high salinity, drought) of degraded soils easily lead to microbial inactivation. Current technologies often involve the direct addition of microorganisms, resulting in low survival rates and difficulty in forming stable microbial communities. Based on the principle of microbial adsorption-encapsulation, stress-resistant microorganisms are immobilized within the porous network of an amphiphilic carrier. The carrier's protective effect isolates them from the extreme environment, while the nutrients adsorbed by the carrier provide energy for microbial growth, promoting microbial metabolism and achieving a synergistic effect of microbial remediation and carrier-based nutrient retention. The specific implementation process is as follows:

[0034] Salt-tolerant nitrogen-fixing bacteria and desulfurizing Vibrio bacteria were selected as stress-resistant functional microorganisms. Salt-tolerant nitrogen-fixing bacteria can convert atmospheric nitrogen into ammonia nitrogen, replenishing soil nitrogen, while desulfurizing Vibrio bacteria can reduce soil salinity. Together, they synergistically improve soil fertility and remediation effects. The composite carrier obtained in step three was added to sterile water and stirred to form a suspension. The pH of the system was adjusted to 6.0-7.0, followed by the addition of a mixed bacterial solution of salt-tolerant nitrogen-fixing bacteria and desulfurizing Vibrio bacteria. The mixture was stirred at room temperature for a preset adsorption time, allowing the microorganisms to initially adsorb onto the carrier surface. Then, an encapsulation agent was added, and the reaction was continued for a preset time. Through an adsorption-encapsulation composite method, the microorganisms were fixed within the three-dimensional porous network structure of the carrier, forming stable bacterial clusters. Finally, after low-temperature drying, a composite degraded soil conditioner based on nanotechnology was obtained.

[0035] This adsorption-embedding composite immobilization method significantly improves the survival rate of microorganisms in extreme soil environments, and the stability of the microbial community is significantly enhanced compared to existing single adsorption or embedding methods. Existing technologies disclose composite conditioners combining microorganisms and nanomaterials, but these use direct mixing methods, which easily lead to microbial inactivation. The unique approach combines adsorption and embedding, utilizing the porous structure of the carrier to achieve deep immobilization of microorganisms. Simultaneously, the water and nutrients adsorbed by the carrier provide growth support for the microorganisms, and the organic acids produced by microbial metabolism promote the reaction efficiency of the nano-mineralization materials, forming a cycle of "carrier protecting microorganisms - microorganisms enhancing carrier function," thus improving the long-term effectiveness of soil remediation.

[0036] Step 5: Conditioner Application and Efficacy Testing: To verify the actual effect of the conditioner in the target application scenario, it is necessary to determine a reasonable application method and testing indicators based on the characteristics of the composite degraded soil and the growth requirements of corn. By comparing with existing conditioners, the synergistic advantages of this solution will be highlighted, providing a basis for actual farmland application. The specific implementation process is as follows:

[0037] Degraded farmland in arid and semi-arid regions of northern China was selected. The soil pH was 8.6, total salt content was 0.35%, Cd content was 0.6 mg / kg, and Pb content was 120 mg / kg. The crop planted was maize. The conditioner prepared in Example 1 was evenly spread on the soil surface according to the preset dosage, and then tilled into the soil to a depth of 15-20 cm to ensure that the conditioner was fully mixed with the soil. The control group was treated with a conventional nano-conditioner (containing only nano-hydroxyapatite and biochar). Other planting conditions (irrigation and fertilization) were kept consistent. Throughout the maize's growth period, soil salinity, heavy metal (Cd, Pb) content, and soil water retention were regularly tested. At the same time, the emergence rate, plant height, yield, and stress resistance (growth under drought and saline-alkali stress) of the maize were recorded.

[0038] The conditioner prepared in this solution exhibits significant synergistic improvement effects in the target application scenario. Compared with existing conventional nano-conditioners, it reduces soil salinity more significantly, significantly improves heavy metal fixation rate, and significantly enhances soil water retention. It also substantially increases maize emergence rate, plant height, and yield, and significantly strengthens salt and drought tolerance. Existing conditioners can only address heavy metal pollution or water retention issues individually, failing to simultaneously address multiple problems. The unique technical approach lies in integrating the functions of nano-mineralization materials, nanoenzymes, and microorganisms through an amphiphilic carrier, forming a synergistic system of "pollution remediation - water and fertilizer retention - crop stress resistance." This overcomes the limitations of existing single-function technologies, achieving highly efficient improvement of complex degraded soils and providing a stable soil environment for maize growth.

[0039] Example 2:

[0040] Step 1: Preparation of Amphiphilic Nanocomposite Support: Based on Example 1, the ratio of modified montmorillonite nanoparticles to modified carbon nanotubes in the amphiphilic nanocomposite support was adjusted to investigate the effect of the support component ratio on loading capacity and dispersion stability. Based on the proportion effect of nanomaterial assembly, different ratios will change the pore size and distribution of the three-dimensional network structure, thus affecting the loading efficiency of functional components. Therefore, by optimizing the ratio, the overall performance of the support can be further improved. The specific implementation process is as follows:

[0041] The same montmorillonite nanoparticles and carbon nanotubes as in Example 1 were selected, and the same carboxylation modification and polyethylene glycol segment grafting modification methods were used. The modified montmorillonite nanoparticles and modified carbon nanotubes were mixed at a mass ratio of 2:1, and deionized water was added to form a suspension. The suspension was then subjected to medium-to-high power ultrasonic treatment for a preset time to directionally assemble a three-dimensional porous network structure. After drying and pulverization, an amphiphilic nanocomposite carrier was obtained.

[0042] The amphiphilic nanocomposite carrier prepared with this ratio exhibits a more uniform pore distribution in its three-dimensional network structure. Compared to the ratio in Example 1, it shows a slight increase in the adsorption capacity for nanomineralized materials, but its dispersion stability is slightly weaker. Existing technologies do not optimize the carrier composition ratio for the needs of composite degraded soil remediation, often employing random mixing. The unique technique lies in adjusting the ratio of the two modified nanomaterials to achieve precise control of the carrier's pore structure, adapting to the loading requirements of different functional components and laying the foundation for subsequent functional synergy. Compared to the random ratios of existing technologies, the loading specificity and efficiency are significantly improved.

[0043] Steps two through five: The implementation process of steps two through five is the same as in Example 1, except for the different ratio of the amphiphilic nanocomposite carrier. Application effect tests show that the soil water retention rate improvement of the conditioner prepared in this example is slightly lower than that in Example 1, while the heavy metal fixation rate and crop stress resistance improvement effects are similar to those in Example 1. It is suitable for improving composite degraded soils with slightly lower water retention requirements.

[0044] Example 3:

[0045] Steps 1 to 2: The implementation process of steps 1 to 2 is the same as that of Example 1, to ensure the stable loading effect of the amphiphilic nanocomposite carrier and the nanomineralized material.

[0046] Step 3: Loading Nanozymes: Based on Example 1, the type of nanozyme was changed to explore the effects of different nanozymes on crop stress resistance. Given the differences in enzyme activity among different nanozymes, Fe-doped Prussian blue nanoparticles also exhibit peroxidase-like activity, and Fe element promotes crop growth. By comparing the application effects of different nanozymes, the applicability of the technical solution was expanded. The specific implementation process is as follows:

[0047] Fe-doped Prussian blue nanoparticles were selected as nanozymes. The composite carrier loaded with nanomineralized materials obtained in step two was added to the dispersion and stirred evenly. Then, Fe-doped Prussian blue nanoparticle powder was slowly added and stirred at room temperature for a preset time. The nanozymes were anchored in the hydrophobic region of the carrier by utilizing the hydrophobic effect. After drying, the composite carrier loaded with nanomineralized materials and nanozymes was obtained.

[0048] The composite carrier loaded with Fe-doped Prussian blue nanoparticles showed slightly lower efficiency in scavenging reactive oxygen species in crops compared to the Zn-doped Prussian blue nanoparticles in Example 1. However, the Fe element can supplement the trace elements required for crop growth and promote chlorophyll synthesis in maize leaves. Existing technologies mostly fix single nanozymes without exploring the compatibility of different nanozymes. The unique approach lies in changing the type of nanozyme and combining it with the directional anchoring function of the carrier to achieve a synergistic effect between stress resistance and nutrient supplementation. Compared to the application of single nanozymes in existing technologies, this approach offers more comprehensive functionality and is adaptable to the needs of crops under different soil fertility conditions.

[0049] Steps four and five: The implementation process of steps four and five is the same as in Example 1, except for the type of nanozyme. Application effect tests show that the conditioner prepared in this example increases the chlorophyll content of crops more significantly than in Example 1, while its improvement in salt and drought tolerance is slightly lower than in Example 1. It is suitable for improving complex degraded soils lacking Fe element.

[0050] Example 4:

[0051] Steps 1 to 3: The implementation process of steps 1 to 3 is consistent with that of Example 1, ensuring the stability of the synergistic effect of the amphiphilic nanocomposite carrier, nanomineralized material and nanoenzyme.

[0052] Step 4: Immobilizing Stress-Resistant Microorganisms: Based on Example 1, the types of stress-resistant microorganisms were changed to explore the impact of different microbial communities on soil remediation. *Azospirillum* has strong salt-tolerance and nitrogen-fixing capabilities, while sulfur-reducing bacteria can efficiently reduce soil salinity. The synergistic effect of both can further enhance soil fertility and desalination. By optimizing the microbial combination, the specificity of the technical solution is improved. The specific implementation process is as follows: *Azospirillum* and sulfur-reducing bacteria were selected as stress-resistant microorganisms. The composite carrier obtained in Step 3 was added to sterile water and stirred to form a suspension. The pH of the system was adjusted to 6.0 to 7.0. A mixed bacterial solution of *Azospirillum* and sulfur-reducing bacteria was added, and the mixture was stirred at room temperature for a preset adsorption time. An encapsulating agent was added to continue the reaction. The microorganisms were immobilized in the carrier network through an adsorption-encapsulation composite method, and the conditioner was obtained after low-temperature drying.

[0053] This microbial combination exhibits higher nitrogen fixation and desalination efficiency than the microbial combination in Example 1, with a more significant increase in soil nitrogen content and a greater reduction in salinity. Existing technologies often employ fixed microbial combinations without optimization for soil salinity and fertility conditions. The unique approach lies in adjusting the microbial combination, combined with the protective and nutrient supply functions of the carrier, to achieve precise synergy between desalination and fertility enhancement. Compared to the fixed microbial combinations in existing technologies, this approach demonstrates a more pronounced remediation effect on high-salt, low-fertility soils.

[0054] Step 5: Application and Effect Testing of Conditioner: The implementation process of Step 5 is the same as in Example 1, except for the type of microorganism. The application effect test shows that the conditioner prepared in this example reduces soil salinity and increases nitrogen content more significantly than in Example 1, while the heavy metal fixation rate is similar to that in Example 1. It is suitable for improving complex degraded soils with extremely high salinity. See Table 1 below:

[0055] Parameter item Example 1 Example 2 Example 3 Example 4 Variable parameter Modified montmorillonite: carbon nanotube = 2.5:1, Zn-doped nano Prussian blue, salt-tolerant nitrogen-fixing bacteria + desulfurization bacteria Modified montmorillonite: carbon nanotube = 2:1, Zn-doped nano Prussian blue, salt-tolerant nitrogen-fixing bacteria + desulfurization bacteria Modified montmorillonite: carbon nanotube = 2.5:1, Fe-doped nano Prussian blue, salt-tolerant nitrogen-fixing bacteria + desulfurization bacteria Modified montmorillonite: carbon nanotube = 2.5:1, Zn-doped nano Prussian blue, nitrogen-fixing bacteria + sulfur-reducing bacteria Soil water retention rate Significant Medium Significant Significant Heavy metal (Cd, Pb) fixation rate Significant Significant Significant Significant Crop stress tolerance Significant Significant Medium Significant Applicable scenario General-purpose composite degraded soil Composite degraded soil with low water retention requirement Composite degraded soil with Fe element deficiency Composite degraded soil with high salt and low fertilizer

[0056] Table 1: Comparison of data from the examples.

[0057] In summary, the core innovation of this technical solution lies in using the directional assembly of amphiphilic nanocomposite carriers as a framework to integrate the synergistic repair functions of nanomineralization and microorganisms with the stress-resistance functions of nanoenzymes, forming a multi-dimensional synergistic system. Existing publicly available documents only involve the physical mixing of nano-montmorillonite and carbon nanotubes as carriers, without amphiphilic modification and directional assembly; existing publicly available documents disclose the immobilization of heavy metals with nano-hydroxyapatite, but without combining it with a carrier; existing publicly available documents use nanoenzymes alone, without forming a synergistic system.

[0058] This technical solution's unique approach lies in constructing a three-dimensional network carrier through amphiphilic modification and directional assembly, achieving partitioned loading and stable dispersion of functional components. This addresses the pain points of existing technologies, such as nanomaterial aggregation, microbial inactivation, and limited functionality. Through in-situ deposition of nanomineralized materials, directional anchoring of nanoenzymes, and adsorption-embedding of microorganisms, a closed-loop synergistic effect of "repair-water retention-stress resistance-fertility enhancement" is formed, far exceeding the effects of using any single technology or simply combining them. Furthermore, by adjusting the carrier ratio, nanoenzyme types, and microbial combinations, the applicability of the technical solution is expanded, providing a new pathway for the improvement of complex degraded soils, aligning with the trend of sustainable agricultural development.

Claims

1. A soil conditioner based on nanotechnology for water and fertilizer retention, characterized in that: It includes an amphiphilic nanocomposite carrier, nanomineralized materials, nanoenzymes, and stress-resistant functional microorganisms. By mass percentage, the amphiphilic nanocomposite carrier accounts for 30%-50%, the nanomineralized materials for 15%-25%, the nanoenzymes for 5%-10%, and the stress-resistant functional microorganisms for 20%-35%. The amphiphilic nanocomposite carrier is a three-dimensional porous network structure formed by the directional assembly of modified nano-montmorillonite and carbon nanotubes through grafting hydrophilic carboxyl groups and hydrophobic polyethylene glycol segments. The nanomineralized materials, nanoenzymes, and stress-resistant functional microorganisms are loaded within the three-dimensional porous network structure.

2. The soil water-retaining and fertilizer-retaining conditioner based on nanotechnology as described in claim 1, characterized in that: The preparation process of the amphiphilic nanocomposite carrier is as follows: carboxylation modification of nano-montmorillonite, polyethylene glycol segment grafting modification of carbon nanotubes, mixing the modified nano-montmorillonite and modified carbon nanotubes at a mass ratio of 2-3:1, and directional assembly under ultrasonic assistance to form a three-dimensional porous network structure.

3. The soil water-retaining and fertilizer-retaining conditioner based on nanotechnology as described in claim 2, characterized in that: The nano-mineralized material is nano-hydroxyapatite, which is chemically bonded to the carboxyl groups on the surface of the amphiphilic nanocomposite carrier through in-situ deposition and loaded onto the pore walls of the three-dimensional porous network structure.

4. The soil water-retaining and fertilizer-retaining conditioner based on nanotechnology as described in claim 3, characterized in that: The nanozyme is a Zn-doped Prussian blue nanoparticle that is anchored to the polyethylene glycol segment region of an amphiphilic nanocomposite carrier through hydrophobic interactions and exhibits peroxidase-like activity.

5. The soil water-retaining and fertilizer-retaining conditioner based on nanotechnology as described in claim 4, characterized in that: The stress-resistant functional microorganisms include salt-tolerant nitrogen-fixing bacteria and desulfurizing Vibrio, which are fixed in the three-dimensional porous network structure of the amphiphilic nanocomposite carrier through an adsorption-embedding composite method to form stable bacterial clusters.

6. The soil water-retaining and fertilizer-retaining conditioner based on nanotechnology as described in claim 5, characterized in that: By mass percentage, the amphiphilic nanocomposite carrier accounts for 35%-45%, nano hydroxyapatite accounts for 18%-22%, Zn-doped nano Prussian blue accounts for 6%-8%, and stress-resistant functional microorganisms account for 25%-30%.

7. The method for preparing a soil water-retaining and fertilizer-retaining conditioner based on nanotechnology as described in any one of claims 1-6, characterized in that: Includes the following steps: The first step is to prepare an amphiphilic nanocomposite support; the second step is to deposit and load nanomineral materials onto the amphiphilic nanocomposite support in situ. The third step is to anchor the nanozyme onto the amphiphilic nanocomposite carrier; the fourth step is to fix the stress-resistant functional microorganisms onto the amphiphilic nanocomposite carrier through an adsorption-embedding composite method and mix them evenly to obtain the conditioner.

8. The method for preparing the soil water-retaining and fertilizer-retaining conditioner based on nanotechnology as described in claim 7, characterized in that: In the first step, after the carboxyl-modified montmorillonite nanoparticles are mixed with polyethylene glycol segment grafted carbon nanotubes, the ultrasonic power is medium to high, and the assembly temperature is controlled between room temperature and 40°C.

9. The preparation method of the soil water-retaining and fertilizer-retaining conditioner based on nanotechnology as described in claim 8, characterized in that: In the second step, the reaction temperature for in-situ deposition is 50°C to 70°C, and the reaction time is a preset duration; in the fourth step, the pH value of the adsorption-embedding composite process is controlled between 6.0 and 7.0.

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