A nano-composite fertilizer granule with saline-alkali soil improvement and slow-release effect and a preparation method thereof

Abstract

The present application relates to the field of agricultural environmental functional materials and soil improvement technology, and provides a nano composite pesticide fertilizer granule with saline-alkali soil improvement and slow release effect and a preparation method thereof.The nano composite pesticide fertilizer granule comprises, from inside to outside, a compound fertilizer core, a nutrition synergistic adsorption layer, a nano preparation slow release layer and a pesticide fertilizer functional coating layer.The present application uses hydrotalcite and / or hydroxyapatite as a carrier substrate to load pesticide active ingredients, simultaneously loads essential nutrient elements and saline-alkali soil improvement materials, and combines the design of a multi-layer structure to realize the synergistic effect of multiple components.The obtained nano composite pesticide fertilizer granule has the functions of soil structure improvement, crop nutrition supply and persistent pest control;at the same time, the preparation process of the nano composite pesticide fertilizer granule is simple, economical and environmentally friendly, and is suitable for the pest control and soil improvement of saline-alkali soil crops, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of agricultural environmental functional materials and soil improvement technology, and in particular to a nano-composite fertilizer granule with saline-alkali soil improvement and slow-release effects and its preparation method. Background Technology

[0002] The main characteristic of saline-alkali soil is its high content of water-soluble salts or alkaline substances. Due to the high salt and alkalinity, soil organic matter is destroyed and lost, and trace elements are scarce. The soil is sticky when wet and hard when dry, often with white salt and alkali deposits on the surface. Aeration and water permeability are poor, and crop roots frequently suffer from poisoning, root rot, and death. Even with large amounts of fertilizer applied, crops cannot absorb and utilize it, resulting in high input and low output. These soils are characterized by high levels of water-soluble salts (Na₂O₃). + Cl - Excessive accumulation of organic matter and sodium ions (pH 8.5~10.2) leads to a decrease in the degradation rate of soil organic matter, a reduction in the bioavailability of trace elements, and the formation of a dense, compacted structure. This "wet and sticky, dry and hard" degradation characteristic not only causes root osmotic stress and ion toxicity in crops, but also significantly reduces fertilizer utilization, creating a vicious cycle of "fertilization-loss-reapplication".

[0003] Furthermore, traditional methods of applying pesticides and fertilizers separately suffer from low utilization rates, environmental pollution, and high labor costs. Conventional pesticide formulations are prone to degradation or leaching, resulting in short-lasting effects. Compound fertilizers (such as nitrogen, phosphorus, and potassium fertilizers) require multiple top-dressings to maintain their effectiveness. While there are existing reports on preparing compound pesticide-fertilizer mixtures from pesticides and fertilizers, these typically involve a simple mixing of pesticide active ingredients and fertilizer components. The resulting compound pesticide-fertilizer lacks a slow-release effect and cannot improve saline-alkali soil. Summary of the Invention

[0004] In view of this, the present invention provides a nano-composite fertilizer granule with saline-alkali soil improvement and slow-release effects, and a method for preparing the same. The composite fertilizer granule provided by the present invention combines saline-alkali soil improvement and slow-release effects, and has broad application prospects.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] A nano-composite fertilizer granule with saline-alkali soil improvement and slow-release effects comprises, from the inside out, a compound fertilizer core, a nutrient-enhancing adsorption layer, a nano-formulation slow-release layer, and a fertilizer-pesticide functional coating layer.

[0007] The core components of the compound fertilizer include essential plant nutrients;

[0008] The nutrient-enhancing adsorption layer comprises pesticide adsorption materials and saline-alkali soil amendments. The pesticide adsorption materials include adsorbents and pesticide active ingredients loaded in the adsorbents. The adsorbents include one or more of biochar, attapulgite, diatomaceous earth, and bentonite. The saline-alkali soil amendments include one or more of superphosphate, fulvic acid, zinc humic acid, and amino acids.

[0009] The components of the nano-formulation sustained-release layer include a nano-sustaining formulation, which comprises a nano-carrier material and a pesticide active ingredient loaded in the nano-carrier material; the nano-carrier material comprises one or both of hydrotalcite and hydroxyapatite.

[0010] The components of the fertilizer-medicine functional coating layer include one or more of polysaccharides and polyvinyl alcohol.

[0011] Preferably, the essential plant nutrients include one or more of macroelements, mesoelements, and microelements; the macroelements include one or more of N, P, and K; the mesoelements include one or more of Ca, Mg, and S; and the microelements include one or more of Fe, Zn, Mn, B, and Cu.

[0012] Preferably, the compound fertilizer core comprises the following components in parts by weight: 50-70 parts of macroelements, 1-5 parts of mesoelements, and 1-5 parts of microelements.

[0013] Preferably, the nutrient-enhancing adsorption layer comprises the following components in parts by weight: 5-10 parts of pesticide adsorption material, 1-5 parts of superphosphate, 1-5 parts of fulvic acid, 0.5-5 parts of zinc humic acid, and 0.5-2 parts of amino acids.

[0014] Preferably, the pesticide active ingredients used in the nutrient-enhancing adsorption layer and the nano-formulation slow-release layer independently include one or more of abamectin, emamectin benzoate, dinotefuran, and thiamethoxam.

[0015] The mass ratio of pesticide active ingredient to nanocarrier material in the nano-formulation sustained-release layer is 1~5:1~5;

[0016] The hydrotalcite is magnesium aluminum hydrotalcite; the particle size of the nanocarrier material is ≤100nm, and the PDI is <0.3.

[0017] Preferably, the polysaccharide includes one or more of alginate, chitosan, and carboxymethyl cellulose.

[0018] Preferably, the mass ratio of the compound fertilizer core, the nutrient-enhancing adsorption layer, the nano-preparation slow-release layer, and the fertilizer-pesticide functional coating layer is 60~80: 10~25: 2~10: 1~5.

[0019] This invention also provides a method for preparing the nanocomposite fertilizer granules with saline-alkali land improvement and slow-release effects described in the above-mentioned scheme, comprising the following steps:

[0020] The raw materials for preparing compound fertilizer cores are granulated to obtain compound fertilizer cores;

[0021] The compound fertilizer core, pesticide adsorption material and saline-alkali soil amendment are granulated to form a nutrient-enhancing adsorption layer on the surface of the compound fertilizer core, thus obtaining composite particles.

[0022] The composite particles and the nano-sustained-release formulation are mixed and coated to obtain coated particles;

[0023] The raw materials for preparing the coated granules and the functional coating layer of the fertilizer and pesticide are mixed and coated to obtain the nano-composite fertilizer and pesticide granules with saline-alkali soil improvement and slow-release effects.

[0024] When the nanocarrier material is hydrotalcite, the preparation method of the nano-sustained-release formulation includes:

[0025] A sodium hydroxide solution and a mixed aqueous solution of metal salt and pesticide active ingredient were mixed and subjected to a co-precipitation reaction to obtain a nano-sustained-release formulation;

[0026] When the nanocarrier material is hydroxyapatite, the preparation method of the nano-sustained-release formulation includes:

[0027] An alcoholic solution of the active pesticide ingredient and an aqueous dispersion of hydroxyapatite were mixed for adsorption, followed by solid-liquid separation to obtain a nano-sustained-release formulation and a supernatant.

[0028] Preferably, the metal salt in the mixed aqueous solution of the metal salt and pesticide active ingredient includes magnesium salt and aluminum salt;

[0029] The preparation method of the pesticide adsorbent material includes: mixing the supernatant with an adsorbent for adsorption to obtain the pesticide adsorbent material.

[0030] Preferably, the coating temperature is 20~35℃ and the rotation speed is 800~1000rpm.

[0031] This invention provides a nano-composite fertilizer-pesticide granule with saline-alkali soil improvement and slow-release effects. From the inside out, it comprises a compound fertilizer core, a nutrient-enhancing adsorption layer, a nano-formulation slow-release layer, and a fertilizer-pesticide functional coating layer. The compound fertilizer core contains essential plant nutrients. The nutrient-enhancing adsorption layer comprises pesticide adsorption materials and saline-alkali soil improvement substances. The pesticide adsorption materials include an adsorbent and an active pesticide ingredient loaded in the adsorbent. The adsorbent includes one or more of biochar, attapulgite, diatomaceous earth, and bentonite (which also have soil improvement effects). The saline-alkali soil amendment includes one or more of superphosphate, fulvic acid, zinc humic acid, and amino acids; the nano-formulation slow-release layer comprises a nano-slow-release formulation, which includes a nano-carrier material and a pesticide active ingredient loaded on the nano-carrier material; the nano-carrier material includes one or both of hydrotalcite (LDH) and hydroxyapatite (HAP); the pesticide-fertilizer functional coating layer comprises one or more of polysaccharides and polyvinyl alcohol; the pesticide active ingredient used in the nutrient-enhancing adsorption layer and the nano-formulation slow-release layer is thiamethoxam. The nano-composite pesticide-fertilizer granules provided by this invention have a four-layer composite system. Through a progressive design of core-adsorption layer-slow-release layer-coating layer, precise release and synergistic effect of pesticide and fertilizer components in the soil are achieved; a controlled-release technology system has been developed based on nanomaterials (hydrotalcite / hydroxyapatite), overcoming the technical bottlenecks of traditional pesticides' easy decomposition and short-lasting effect in saline-alkali soils, meeting the development needs of pesticide reduction and fertilizer efficiency, and possessing significant ecological and economic value. Specifically, compared with the prior art, the nanocomposite fertilizer granules of the present invention have the following beneficial effects:

[0032] Nano-release formulations are characterized by small size and large specific surface area. This invention utilizes nanomaterials such as hydrotalcite to intercalate and load pesticide components, which not only enhances the absorption and conduction of pesticide active ingredients in crops, but also addresses the technical bottlenecks of traditional pesticides being prone to decomposition and inactivation in saline-alkali soils and having short effective periods. By selecting hydrotalcite / hydroxyapatite as a nanocarrier for slow-release pesticides and fertilizers in saline-alkali soils, the structure can be maintained in alkaline non-target environments, reducing ineffective release and ecological risks.

[0033] Significant synergistic effect of multiple components: This invention combines the functions of saline-alkali soil improvement and pesticide-fertilizer integration. The compound fertilizer core provides essential plant nutrients, while the nano-formulation slow-release layer enables multi-level controlled release of pesticide active ingredients, forming a dual release curve of "nutrient-plant protection" that meets crop growth needs. Simultaneously, the nutrient-enhancing adsorption layer combines water retention and soil improvement with slow-release pesticides, enhancing the comprehensive management of saline-alkali soil and pest control capabilities. The pesticide-fertilizer functional coating layer reduces pesticide loss and migration. In summary, this invention uses hydrotalcite and / or hydroxyapatite as a carrier matrix to load pesticide active ingredients, while simultaneously combining essential plant nutrients with saline-alkali soil improvement materials. The multi-layered structure design achieves synergistic effects of multiple components, resulting in nano-composite pesticide-fertilizer granules that combine soil structure improvement, crop nutrient supply, and continuous pest and disease control, overcoming the limitations of traditional single-function products that struggle to achieve synergistic effects.

[0034] The invention demonstrates significant effects in improving saline-alkali land: The nutrient-enhancing adsorption layer comprises pesticide adsorption materials and saline-alkali soil amendments. These adsorbents and amendments exhibit multi-dimensional synergistic advantages in saline-alkali land improvement. Biochar adsorbs salt ions and regulates the soil microenvironment through its porous structure; attapulgite selectively captures sodium ions and improves soil structure using nanorod crystals; diatomaceous earth acts as a rigid framework to prevent salt migration and slowly release nutrients; and fulvic acid, zinc humic acid, and amino acids achieve ecological restoration by chelating salts, promoting aggregate formation, and enhancing crop resistance. The nanocomposite pesticide-fertilizer granules of this invention can be used to improve coastal saline-alkali soils with a pH of 7.5–9.1 and an alkalinity of 6.6–72%, effectively improving soil aggregate structure and water and fertilizer retention capacity. Through the ion exchange effect of the nutrient-enhancing adsorption layer, it reduces soil alkalinity and breaks the vicious cycle of "compaction-infertility" in saline-alkali land.

[0035] This invention demonstrates outstanding controlled-release performance of pesticides, achieving multi-stage release: In the controlled-release layer of nano-formulations, hydrotalcite and / or hydroxyapatite are used as nanocarrier materials to load pesticide active ingredients. To reduce pesticide waste, further improve quality and efficiency, and increase pesticide loading efficiency, porous materials with both soil-improving and adsorption functions are utilized to adsorb residual pesticide components, further increasing the pesticide loading rate and achieving multi-stage release. Experimental verification shows that the pesticide active ingredients can be continuously released for 21 days. The core-layer coating technology significantly improves pesticide utilization, reduces application frequency, and the nanocarrier material is adaptable to the high pH environment of saline-alkali soils, ensuring the stability of pesticide active ingredients.

[0036] Environmental advantages: The nanocomposite fertilizer granules of this invention have a nearly 100% biodegradable material utilization rate, making them more environmentally friendly. Furthermore, the granule form facilitates mechanized application, saving labor costs compared to traditional separate application of fertilizers and pesticides.

[0037] This invention also provides a method for preparing nanocomposite fertilizer granules with saline-alkali soil improvement and slow-release effects as described above. The preparation method provided by this invention prepares nanocomposite fertilizer granules through granulation and coating processes. No organic solvents are required during preparation, the operation is simple, and it is easy to mass-produce. Attached Figure Description

[0038] Figure 1 The particle size distribution diagram of the hydrotalcite nano-sustained-release formulation prepared in Example 1;

[0039] Figure 2 SEM image of the hydrotalcite nano-sustained-release formulation prepared in Example 1;

[0040] Figure 3 Release curves of hydrotalcite nano-sustained-release formulations with different carrier contents prepared in Example 2;

[0041] Figure 4 SEM image of the nano-hydroxyapatite prepared in Example 3;

[0042] Figure 5 A photograph of the nanocomposite fertilizer granules prepared in Example 7;

[0043] Figure 6 This is a comparison of the growth of cabbage over 21 days in Example 8;

[0044] Figure 7 This is a comparison of the growth of chili plants after the application of medicinal fertilizer in Example 9. Detailed Implementation

[0045] This invention provides a nano-composite fertilizer granule with saline-alkali soil improvement and slow-release effects, comprising, from the inside out, a compound fertilizer core, a nutrient-enhancing adsorption layer, a nano-formulation slow-release layer, and a fertilizer-pesticide functional coating layer.

[0046] In this invention, the core components of the compound fertilizer include essential plant nutrients. These essential plant nutrients preferably include one or more of macronutrients, mesonutrients, and micronutrients. The macronutrients are the three core elements required in the largest quantities for plant growth and must be supplemented in large quantities through fertilizer. The mesonutrients are essential nutrients required by plants in quantities lower than macronutrients but higher than micronutrients, generally accounting for 0.01% to 0.1% of the plant's dry weight. Micronutrients are elements required in very small quantities by plants but are crucial for physiological functions. Specifically, the macronutrients include one or more of N, P, and K, more preferably all of N, P, and K. Specifically, the N, P, and K are preferably provided by nitrogen fertilizer, phosphorus fertilizer, and potassium fertilizer. The mesonutrients include one or more of Ca, Mg, and S. The micronutrients include one or more of Fe, Zn, Mn, B, and Cu.

[0047] In this invention, the core of the compound fertilizer comprises the following components in parts by weight: 50-70 parts of macroelements, specifically 50, 55, 60, or 65 parts; 1-5 parts of mesoelements, specifically 1, 3, or 4 parts; and 1-5 parts of microelements, specifically 1, 3, or 4 parts. In a specific embodiment of this invention, the macroelements preferably include 15-20 parts of nitrogen fertilizer, 20-25 parts of phosphate fertilizer, and 20-25 parts of potassium fertilizer. The nitrogen fertilizer is preferably urea, the phosphate fertilizer is preferably monoammonium phosphate, and the potassium fertilizer is preferably potassium sulfate. In a specific embodiment of this invention, the mass percentages of the macroelements, mesoelements, and microelements are calculated based on the mass of each element.

[0048] In this invention, the nutrient-enhancing adsorption layer comprises pesticide adsorption material and saline-alkali soil amendment material. The pesticide adsorption material comprises an adsorbent and pesticide active ingredients loaded in the adsorbent. The adsorbent comprises one or more of biochar, attapulgite, diatomaceous earth, and bentonite. The preparation method of the biochar preferably includes: pulverizing biomass straw and then carbonizing it to obtain biochar. The carbonization temperature is preferably 500-600℃, and the carbonization time is preferably 60-150 min. The biomass straw is preferably washed and dried before pulverization. The biomass straw preferably includes one or more of rice straw, sorghum straw, corn straw, and wheat straw. After carbonization, the obtained carbonized material is preferably ground and passed through a 200-mesh sieve, and the material passing through the sieve is taken as the biochar of this invention.

[0049] In this invention, the pesticide active ingredients in the nutrient-enhancing adsorption layer preferably include one or more of abamectin, emamectin benzoate, fipronil, and thiamethoxam; the saline-alkali soil amendment material includes one or more of superphosphate, fulvic acid, zinc humic acid, and amino acids.

[0050] In this invention, the nutrient-enhancing adsorption layer preferably comprises the following components in parts by weight: 5-10 parts of pesticide adsorption material, specifically 5, 8, or 9 parts; 1-5 parts of superphosphate, specifically 1, 3, or 4 parts; 1-5 parts of fulvic acid, specifically 1, 3, or 4 parts; 0.5-5 parts of zinc humic acid, specifically 1, 3, or 4 parts; and 0.5-2 parts of amino acids, specifically 0.5, 1, or 2 parts; wherein the amino acids preferably include one or more of glycine, glutamic acid, and aspartic acid.

[0051] In this invention, adsorbents and saline-alkali soil amendments exhibit multi-dimensional synergistic advantages in saline-alkali land improvement. Biochar adsorbs salt ions and regulates the soil microenvironment through its porous structure; attapulgite selectively captures sodium ions and improves soil structure using nanorod crystals; diatomaceous earth blocks salt migration and slowly releases nutrients with its rigid framework; and fulvic acid, zinc humic acid, and amino acids achieve ecological restoration by chelating salts, promoting aggregate formation, and enhancing crop resistance. This invention, by setting up a nutrient-enhancing adsorption layer, can extend the release period of pesticides while effectively improving the soil structure and hydrological function of saline-alkali land.

[0052] In this invention, the components of the nano-formulation sustained-release layer include a nano-sustaining formulation, which comprises a nano-carrier material and a pesticide active ingredient loaded in the nano-carrier material; the nano-carrier material comprises one or both of hydrotalcite and hydroxyapatite; the hydrotalcite is preferably magnesium aluminum hydrotalcite; the particle size of the nano-carrier material is preferably ≤100nm, and the PDI is preferably <0.3; the pesticide active ingredient used in the nano-formulation sustained-release layer preferably includes one or more of abamectin, emamectin benzoate, dinotefuran, and thiamethoxam; the mass ratio of the pesticide active ingredient to the nano-carrier material in the nano-formulation sustained-release layer is preferably 1~5:1~5, specifically 1:1, 0.5:1, or 0.25:1.

[0053] In this invention, the active ingredients of pesticides are chemically stable under acidic conditions, but are easily degraded and lost in the alkaline environment of saline-alkali land, posing a high risk of non-target exposure. Traditional pesticide formulations require frequent application, which can lead to resistance and pollution problems. To address this issue, this invention introduces a nano-formulation slow-release layer into nano-composite pesticide-fertilizer granules. A nano-drug delivery system is prepared using nanomaterials (hydrotalcite and / or hydroxyapatite). This nano-drug delivery system can maintain its structural integrity in neutral or alkaline non-target environments (such as bee activity areas or water bodies), reducing ineffective release and ecological risks. At the same time, the nano-carrier materials used in this invention are inexpensive and have strong penetration and conduction properties within the crop target. The controlled-release technology extends the efficacy period and reduces the frequency and cost of application.

[0054] In this invention, the pesticide-fertilizer functional coating layer comprises one or more of polysaccharides and polyvinyl alcohol; the polysaccharides preferably comprise one or more of alginate, chitosan, and carboxymethyl cellulose; the alginate is preferably sodium alginate and calcium alginate; in specific embodiments of this invention, the pesticide-fertilizer functional coating layer preferably comprises chitosan and alginate (the mass ratio of chitosan to alginate is preferably 1:1), or comprises carboxymethyl cellulose and alginate, or comprises alginate and polyvinyl alcohol. This invention, by setting a pesticide-fertilizer functional coating layer, can reduce pesticide loss and migration.

[0055] In this invention, the preferred mass ratio of the compound fertilizer core, the nutrient-enhancing adsorption layer, the nano-preparation slow-release layer, and the fertilizer-pesticide functional coating layer is 60~80: 10~25: 2~10: 1~5, and more preferably 65~75: 15~20: 3~8: 2~4.

[0056] The nano-composite fertilizer granules provided by this invention have the functions of soil structure improvement, crop nutrient supply and continuous pest and disease control. They are suitable for pest and disease control and soil fertility improvement of crops in saline-alkali land, where the pH value of the saline-alkali land is 7.5~9.1 and the alkalinity is 6.6~72%.

[0057] This invention also provides a method for preparing the nanocomposite fertilizer granules with saline-alkali land improvement and slow-release effects described in the above-mentioned scheme, comprising the following steps:

[0058] The raw materials for preparing compound fertilizer cores are granulated to obtain compound fertilizer cores;

[0059] The compound fertilizer core, pesticide adsorption material and saline-alkali soil amendment are mixed and granulated to form a nutrient-enhancing adsorption layer on the surface of the compound fertilizer core, thus obtaining composite particles.

[0060] The composite particles, the nano-sustained-release formulation, and water are mixed and coated to obtain coated particles.

[0061] The raw materials for preparing the coated granules and the functional coating layer of the fertilizer and pesticide are mixed and coated to obtain the nano-composite fertilizer and pesticide granules with saline-alkali soil improvement and slow-release effects.

[0062] This invention granulates the raw materials for preparing compound fertilizer cores (referred to as the first granulation) to obtain compound fertilizer cores. In this invention, the raw materials for preparing the compound fertilizer cores specifically provide macro-elements, meso-elements, and micro-elements. The raw materials providing macro-elements preferably include one or more of urea, monoammonium phosphate, and potassium sulfate. This invention does not have special requirements for the raw materials providing meso- and micro-elements; materials well-known to those skilled in the art can be used. Specifically, well-known meso- and micro-element fertilizers can be used, selected according to the elements required in the compound fertilizer. Before the first granulation, the raw materials for preparing the compound fertilizer cores are preferably ground and sieved, and then the sieved raw materials are mixed evenly. The mesh size of the sieve used for sieving is preferably 50-100 mesh. The first granulation is preferably roller-driven humidified granulation, and the first granulation is preferably carried out in a rotary drum granulator. In a specific embodiment of this invention, the evenly mixed raw materials are preferably added to the rotary drum granulator, and then atomized water is introduced for rolling humidified granulation. The particle size of the compound fertilizer core is preferably 2-3 mm.

[0063] After obtaining the compound fertilizer core, the present invention mixes the compound fertilizer core, pesticide adsorbent material, and saline-alkali soil amendment material for granulation (referred to as second granulation), forming a nutrient-enhancing adsorption layer on the surface of the compound fertilizer core to obtain composite particles. In the present invention, the preferred method for preparing the pesticide adsorbent material includes: mixing the supernatant (the supernatant remaining during the preparation of hydroxyapatite nano-slow-release formulation, which will be described in detail later) with an adsorbent for adsorption (referred to as first adsorption) to obtain the pesticide adsorbent material; the mass ratio of the solution containing the pesticide active ingredient to the adsorbent is preferably 5~20:1, more preferably 10~15:1; the preferred time for the first adsorption is 2~6 hours, and the first adsorption is preferably carried out under stirring conditions; after the first adsorption is completed, the obtained pesticide adsorbent material is preferably filtered and then dried.

[0064] In this invention, the conditions for the second granulation are preferably the same as those for the first granulation. In a specific embodiment of this invention, preferably after the first granulation is completed, the mixture of pesticide adsorbent and saline-alkali soil amendment is added to a rotary drum granulator to continue the second granulation. After the second granulation is completed, preferably the resulting composite particles are removed and dried.

[0065] After obtaining the composite particles, the present invention mixes the composite particles with the nano-controlled-release formulation for coating to obtain coated particles. In the present invention, when the nanocarrier material is hydrotalcite, the preparation method of the nano-controlled-release formulation (denoted as hydrotalcite nano-controlled-release formulation) includes: mixing sodium hydroxide solution and a mixed aqueous solution of metal salt and pesticide active ingredient for co-precipitation reaction to obtain the nano-controlled-release formulation; the concentration of the sodium hydroxide solution is preferably 0.2wt%~2wt%, specifically 0.5wt% or 2wt%; the metal salt in the mixed aqueous solution of metal salt and pesticide active ingredient preferably includes magnesium salt and aluminum salt, specifically magnesium nitrate and aluminum nitrate; the preparation method of the mixed aqueous solution of metal salt and pesticide active ingredient preferably includes: mixing magnesium salt, aluminum salt, pesticide technical and water to obtain a mixed aqueous solution of metal salt and pesticide active ingredient; the total mass fraction of magnesium salt and aluminum salt in the mixed aqueous solution of metal salt and pesticide active ingredient is preferably 1wt%~5wt%, specifically 0.5wt% or 2wt%. The content of the magnesium salt and aluminum salt is 2wt% or 3wt%; the molar ratio of the magnesium salt and aluminum salt is preferably 1~3:1, specifically 1.3:1, 2:1 or 3:1; the mass fraction of the pesticide active ingredient in the mixed aqueous solution of the metal salt and pesticide active ingredient is 1wt%~5wt%, specifically 2wt% or 3wt%; the volume ratio of the sodium hydroxide solution and the mixed aqueous solution of the metal salt and pesticide active ingredient is preferably 0.5:1~1:1; the coprecipitation reaction is preferably carried out under shear conditions, and the shearing time is preferably 5~20min; after shearing, the resulting reaction solution is preferably allowed to stand for 5~15min, then the pH of the system is adjusted to 9~10, and then allowed to stand again for 1~5h, and then centrifuged. The resulting lower precipitate is the hydrotalcite nano-slow-release formulation; the supernatant obtained by centrifugation is preferably used as a raw material for preparing pesticide adsorbent materials.

[0066] In this invention, when the nanocarrier material is hydroxyapatite, the preparation method of the nano-sustained-release formulation (denoted as hydroxyapatite nano-sustained-release formulation) includes: mixing an alcoholic solution of pesticide active ingredient and an aqueous dispersion of hydroxyapatite for adsorption (denoted as second adsorption), followed by solid-liquid separation to obtain the nano-sustained-release formulation and a supernatant; the preferred method for preparing the alcoholic solution containing pesticide active ingredient includes: dissolving the pesticide technical in alcohol to obtain the alcoholic solution containing pesticide active ingredient; the alcohol is preferably methanol or ethanol; the content of pesticide active ingredient in the alcoholic solution is preferably 1wt%~5wt%; the concentration of the aqueous dispersion of hydroxyapatite is preferably 1wt%~5wt%; the preferred method for preparing the nano-hydroxyapatite is chemical co-precipitation, sol-gel method, or aqueous method. The method can be thermal, microwave, or combustion, but more preferably chemical coprecipitation. The chemical coprecipitation method specifically includes the following steps: adding diammonium hydrogen phosphate solution dropwise to calcium nitrate solution to carry out a coprecipitation reaction, obtaining the hydroxyapatite, specifically nano-hydroxyapatite; the concentration of the diammonium hydrogen phosphate solution is preferably 0.5~1 g / 100 mL, more preferably 0.79 g / 100 mL, and the pH value of the diammonium hydrogen phosphate solution is preferably 10; the concentration of the calcium nitrate solution is preferably 2~2.5 g / 100 mL, more preferably 2.36 g / 100 mL, and the pH value of the calcium nitrate solution is preferably 10; the temperature of the system during the dropwise addition is preferably 40℃, and after the dropwise addition is completed, the mixture is preferably stirred for 40 min, then aged for 12 h, and then the obtained solid product is washed.

[0067] In this invention, the second adsorption time is preferably 24 hours, and the second adsorption is preferably carried out under stirring conditions; after the second adsorption is completed, centrifugation and filtration are preferably performed to obtain the hydroxyapatite nano-slow-release formulation, and the remaining filtrate is the supernatant, which is used in the preparation of pesticide adsorption materials.

[0068] In this invention, the coating is preferably carried out using a small water chestnut-type coating machine, and atomized water is preferably sprayed during the coating process to ensure the viscosity of the material; the coating temperature is preferably 20~35℃, specifically 25℃ or 30℃, and the rotation speed is preferably 800~1000rpm, specifically 850rpm or 900rpm.

[0069] After obtaining the coated granules, the present invention mixes the coated granules with the raw materials for preparing the fertilizer-pesticide functional coating layer for coating, thereby obtaining the nano-composite fertilizer-pesticide granules with saline-alkali soil improvement and slow-release effects. In the present invention, the raw materials for preparing the fertilizer-pesticide functional coating layer are specifically one or more of polysaccharides and polyvinyl alcohol, and the types of polysaccharides will not be elaborated here; the coating conditions are the same as those for the coating described above.

[0070] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0071] All parts in the following examples are by weight.

[0072] Example 1

[0073] Preparation of hydrotalcite nano-sustained-release formulation: Magnesium nitrate, aluminum nitrate (molar ratio of magnesium to aluminum is 1.3:1, total mass of magnesium nitrate and aluminum nitrate is 5.5g), 3g of thiamethoxam technical material and 250mL of water were mixed to obtain a mixed aqueous solution; a sodium hydroxide solution with a concentration of 1.1g / 100mL was prepared; the sodium hydroxide solution was added to the mixed aqueous solution, sheared for 5min, allowed to stand for 15min, adjusted to pH 10, allowed to stand for 40min, and then centrifuged to wash the precipitate to obtain the hydrotalcite nano-sustained-release formulation and supernatant.

[0074] Particle size distribution determination: The prepared hydrotalcite nano-sustained-release formulation was diluted to 0.5% (w / w), ultrasonically vibrated until homogeneous, and the hydrated particle size and PDI of the hydrotalcite nano-sustained-release formulation were determined using a Malvern particle size analyzer at room temperature. Each sample was measured in triplicate, and the average value and standard deviation were calculated. The test results are as follows: Figure 1 As shown. Figure 1 The results show that the hydrotalcite nano-sustained-release formulation prepared in this invention has a small particle size of about 70 nm, a PDI of 0.18, and good dispersibility.

[0075] Electron microscopy morphology characterization: First, the prepared hydrotalcite nano-sustained-release formulation was diluted to a suitable concentration. 5 μL of the solution was evenly dropped onto the smooth surface of a silicon wafer and allowed to dry at room temperature to obtain the sample. The morphology of the prepared hydrotalcite nano-sustained-release formulation was characterized using SEM with an accelerating voltage of 3 kV. The test results are as follows: Figure 2 As shown; according to Figure 2 It can be seen that the hydrotalcite nano-sustained-release formulation prepared by the present invention has a regular morphology and a smooth hexagonal structure.

[0076] Example 2

[0077] Following the preparation method of Example 1, the carrier ratio was changed to prepare hydrotalcite nano-sustained-release formulations with different carrier ratios. Specifically, the addition ratio of magnesium nitrate / aluminum nitrate to thiamethoxam technical was adjusted to prepare three thiamethoxam nano-drug delivery systems Y1, Y2, and Y3 with different hydrotalcite carrier ratios. The mass ratios of thiamethoxam to hydrotalcite in the obtained hydrotalcite nano-sustained-release formulations were 1:1, 0.5:1, and 0.25:1, respectively.

[0078] Characterization of sustained-release performance: To evaluate the in vitro release of the nano-sustained-release formulation, this embodiment determined the cumulative release of thiamethoxam at different time points using dialysis. The specific procedure was as follows: A 50% (v / v) methanol-water solution was used as the simulated release medium. Three hydrotalcite nano-sustained-release formulation samples with different carrier ratios (10 mg of thiamethoxam active ingredient) were accurately weighed, dissolved in 5 mL of 50% methanol, and placed in a treated dialysis bag (8000 Da). Each sample was then suspended in a brown reagent bottle containing 95 mL of 50% methanol solution and placed in a constant-temperature shaking incubator at 25°C. The samples were dialyzed at regular intervals (see [link to details]). Figure 3 Take 2 mL of the release solution from the brown reagent bottle, and then add 2 mL of fresh 50% methanol aqueous solution to ensure that the reaction bottle still contains 100 mL after sampling. Then, dilute the release solution and determine the concentration of thiamethoxam by high performance liquid chromatography to calculate the cumulative release amount of thiamethoxam.

[0079] Test results are as follows Figure 3 As shown. According to Figure 3 It can be seen that hydrotalcite nano-release formulations with different carrier ratios all have a sustained-release effect. Among them, the higher the carrier ratio, the slower the release of pesticide active ingredients and the stronger the sustained-release performance.

[0080] Example 3

[0081] Preparation of nano-hydroxyapatite: Prepare a calcium nitrate tetrahydrate solution of 2.36 g / 100 mL with a pH of 10 and a diammonium hydrogen phosphate solution of 0.79 g / 100 mL with a pH of 10; slowly add the diammonium hydrogen phosphate solution dropwise to the calcium nitrate tetrahydrate solution, keep the reaction system temperature at 40℃, stir for 40 min, and continue aging for 12 h. Wash the precipitate to obtain nano-hydroxyapatite powder.

[0082] Figure 4 This is a SEM image of the nano-hydroxyapatite prepared in this embodiment.

[0083] Example 4

[0084] Preparation of hydroxyapatite nano-sustained-release formulation: The nano-hydroxyapatite powder prepared in Example 3 was mixed with deionized water at a mass ratio of 1:100 to obtain a dispersion. Then, 1 wt% of an alcoholic solution of thiamethoxam pesticide technical was added to the dispersion, sheared for 10 min, stirred for 4 h, and centrifuged to obtain the hydroxyapatite nano-sustained-release formulation.

[0085] Example 5

[0086] Preparation of biochar: Rice straw is washed, dried, crushed, and then carbonized in a carbonization furnace at a temperature of 500℃ for 120 minutes. Finally, it is ground and sieved to obtain biochar.

[0087] Example 6

[0088] Preparation of pesticide adsorbent material (thiamethoxam-loaded biochar): The supernatant remaining from centrifugation in Example 1 was mixed with the biochar prepared in Example 5 at a mass ratio of 20:1, sonicated for 15 min, stirred for 2 h, filtered, and the resulting solid product was dried to obtain thiamethoxam-loaded biochar.

[0089] Example 7

[0090] Preparation of nano-composite fertilizer granules with saline-alkali soil improvement and slow-release effects: 20 parts nitrogen fertilizer (urea), 25 parts phosphate fertilizer (monoammonium phosphate), 25 parts potassium fertilizer (potassium sulfate), 4 parts medium-element fertilizer (containing Ca and Mg elements), and 1 part micro-element fertilizer (containing Fe, Zn, and B elements) were ground separately and passed through a 50-mesh sieve. The sieved materials were then mixed evenly and transferred to a rotary drum granulator with atomized water for rolling humidification and granulation. The granulated particle size was 2-3 mm, yielding a compound fertilizer core. Then, the raw materials for preparing the nutrient-enhancing adsorption layer (5 parts of thiamethoxam-loaded biochar, 4 parts of superphosphate, 5 parts of fulvic acid, 3 parts of zinc humic acid, and 1 part of amino acids (specifically glycine and glutamic acid) prepared in Example 6) were added, and granulation continued. Finally, the prepared granules were removed, dried, and the composite granules were obtained.

[0091] Four parts of the hydrotalcite nano-slow-release formulation prepared in Example 1 were uniformly coated onto the surface of the composite granules (93 parts) using a small water chestnut-type coating machine. Atomized water was sprayed appropriately during the coating process to ensure the granules' stickiness. Finally, a chitosan-alginate (3 parts, with a chitosan-alginate mass ratio of 1:1) was used for coating, resulting in a nano-composite fertilizer granule with saline-alkali soil improvement and slow-release effects. A physical image of the obtained nano-composite fertilizer granule is shown below. Figure 5 As shown.

[0092] pH value determination: The pH value of the nano-composite fertilizer granules prepared in Example 7 was determined according to the "Determination of pH Value of Pesticides" (GB / T1601-1993). The specific procedure was as follows: First, 10g of sample was weighed into a 200mL beaker, 100mL of water was added, and the mixture was stirred vigorously for 1 minute, then allowed to stand for 1 minute. Then, the pH meter was calibrated, and the pH value was measured. The measurement was repeated three times, and the average value was taken (GB / T 1601-1993). The pH value of the nano-composite fertilizer granules was measured to be 6.5, indicating that its acidity and alkalinity are qualified and comply with national regulations.

[0093] The moisture content of the nanocomposite fertilizer granules prepared in Example 7 was determined: The free water content in the nanocomposite fertilizer granules was determined according to the "Determination of Free Water Content in Compound Fertilizers - Vacuum Oven Method" (GB / T8576-2010). 20g of thiamethoxam nanocomposite fertilizer granules was accurately weighed and placed at 50℃±2℃ with a vacuum degree of 6.4×10⁻⁶. 4 Pa ~ 7.1 × 10 4 The nanocomposite fertilizer granules were dried in a constant-temperature vacuum drying oven for 2 hours, then cooled to room temperature in a desiccator and weighed. The measurement was repeated three times, and the average value was taken. The results show that the moisture content of the nanocomposite fertilizer granules prepared in this invention is 3.2%, which meets national standards, indicating that the prepared nanocomposite fertilizer granules have good quality and storage potential.

[0094] The thermal storage stability of the nanocomposite fertilizer granules prepared in Example 7 was determined: The thermal storage stability of the nanocomposite fertilizer granules was evaluated according to GB / T 19136-2003, "Methods for Determination of Thermal Storage Stability of Pesticides". Specifically, 20g of sample was placed in a glass dish to form a smooth and uniform layer. Three parallel samples were stored at 54±2℃ for 14 days. After storage, the samples were removed and placed in a drying oven to cool to room temperature. The drug content was determined within 24 hours. The results showed that the decomposition rate of thiamethoxam in the nanocomposite fertilizer granules was 4.6%, exhibiting a low decomposition rate. According to the "Methods for Determination of Thermal Storage Stability of Pesticides" (GB / T 19136-2003), the nanocomposite fertilizer granules prepared in this invention exhibit good chemical stability under thermal storage conditions.

[0095] Example 8

[0096] This embodiment verifies the effects of a nano-composite fertilizer granule with saline-alkali soil improvement and slow-release effects on the control efficacy and growth of cabbage aphids. The specific experimental steps are as follows:

[0097] This embodiment uses a pot planting experiment for cabbage. The pot dimensions are (length × width × height: 15cm × 15cm × 15cm), and each pot contains 1.0kg of soil (garden soil). Sow the seeds, and when the cabbage has grown to two true leaves, thin the seedlings, leaving one plant per pot. During this period, water every three days with approximately 250mL of water each time. When the cabbage reaches the fifth true leaf stage, apply a fertilizer with different components.

[0098] The uninoculated group underwent four treatments:

[0099] Treatment 1: Do not fertilize;

[0100] Treatment 2: Apply only thiamethoxam nanopesticide with a slow-release effect (hydrotalcite nanoparticle slow-release formulation prepared in Example 1).

[0101] Solution 3: Apply NPK only;

[0102] Treatment 4: Apply the nanocomposite fertilizer granules prepared in Example 7, which have the effects of improving saline-alkali land and slow release.

[0103] Spray once every 3 days, for a total of 3 times, with 5 replicates for each treatment.

[0104] The inoculated group underwent two treatments:

[0105] Treatment 6 (Control): No pesticides or fertilizers were applied;

[0106] Treatment 7: Apply the nanocomposite fertilizer granules prepared in Example 7, which have the effects of improving saline-alkali land and slow release.

[0107] Wingless adult cabbage aphids, purified and cultured in the laboratory, were inoculated with 30 aphids per cabbage plant (evenly transferred to the underside of the leaves using a soft brush). The control efficacy and cabbage growth were assessed on days 3, 5, 7, 14, and 21 after application of the pesticide and fertilizer. The results are shown in Table 1 and [Table data missing]. Figure 6 As shown. Control efficacy = (1 - number of live insects in the treatment group / number of live insects in the control group) × 100%.

[0108] Table 1. Control efficacy of pesticides and fertilizers for cabbage aphids

[0109]

[0110] As can be seen from the data in Table 1, the nano-composite fertilizer granules of this invention maintain high efficacy from 3 to 21 days, exhibiting certain slow-release properties; and according to... Figure 6 It can be seen that the cabbage in the experimental group that applied the nano-composite fertilizer granules of this invention grew significantly better than other experimental groups.

[0111] Example 9

[0112] This embodiment tests the effects of a nano-composite fertilizer granule with saline-alkali soil improvement and slow-release effects on chili pepper growth and saline-alkali soil improvement in different regions. The specific experimental steps are as follows:

[0113] The example experiment used a potted planter method for growing chili peppers. The pots were 8cm x 8cm x 6cm in size (length x width x height). Each pot contained 250g of soil (different types of saline-alkali soil from the coastal area). Sowing was carried out, and when the chili peppers had grown to two true leaves, the seedlings were thinned, leaving one plant per pot. During this period, the plants were watered every three days with about 100mL of water each time.

[0114] Perform four processes respectively:

[0115] Control group: Binzhou saline-alkali soil No. 1, without fertilizer;

[0116] Treatment 1: Binzhou saline-alkali soil No. 1, mixed with fertilizer before sowing;

[0117] Treatment 2: Dongying saline-alkali soil No. 1, mixed with fertilizer before sowing;

[0118] Treatment 3: Dongying saline-alkali soil No. 2, mixed with fertilizer before sowing;

[0119] Treatment 4: Dongying saline-alkali soil No. 3, mixed with fertilizer before sowing;

[0120] The applied fertilizer and pesticide were all nano-composite fertilizer and pesticide granules prepared in Example 7. Soil pH, organic matter, electrical conductivity and alkalinity (CEC) were measured before and 21 days after application. Soil-related index testing methods: pH value was determined using a Leici PHS-3C pH meter according to the standard method of "NY / T 1377-2007 Determination of pH Value in Soil"; organic matter was determined using a fully automated organic matter analyzer JX-S7066 according to the standard method of "NY / T1121.6-2006 Soil Testing Part 6: Determination of Soil Organic Carbon and Organic Matter"; electrical conductivity was determined using a conductivity meter according to the method of "HJ 802-2016"; alkalinity was determined using a Tianbo 50mL burette and an Agilent Technologies 5110 ICP-OES according to the method of "Determination of Exchangeable Sodium in Alkaline Soil and Calculation of Alkalinity" 3.4 of "Soil Agricultural Chemical Analysis Methods"; CEC was determined using a Tianbo 50mL burette according to the EDTA-ammonium acetate exchange method of "Soil Analysis Technical Specifications" (Second Edition).

[0121] The test results are shown in Table 2. Figure 7 This is a comparison of the growth of chili plants after the application of pesticides and fertilizers.

[0122] Table 2. Changes in soil indicators of different types of saline-alkali soils before and after application of pesticides and fertilizers in different regions.

[0123]

[0124] The data in Table 2 show that the application of pesticides and fertilizers had significant effects: both treatments significantly improved the pH, electrical conductivity, and alkalinity of saline-alkali soils, indicating that these treatments were effective in improving saline-alkali soils. Freshwater irrigation in the control group also improved soil indicators, but the effect was not as significant as in the treatment groups.

[0125] The pH value of saline-alkali soil reflects the soil's acidity and alkalinity, and is an important indicator for measuring salinization. A pH > 8.5 indicates strong soil alkalinity, at which point sodium ions in the soil colloids increase significantly, leading to reduced nutrient availability (such as phosphorus and iron). A pH between 7.5 and 8.5 indicates mild alkalization, which may inhibit the root development of some crops. Electrical conductivity (EC) characterizes the total amount of soluble salts in the soil and directly determines the intensity of salt damage. When EC > 4 dS / m (approximately 40 mS / cm), soil salinization is severe, and most crops experience osmotic stress and ion toxicity. An EC of 2-4 dS / m indicates moderate salinity, where salt-tolerant plants can still grow. An EC < 2 dS / m indicates less salt impact, and the salt composition (such as Na) is relatively stable. + / Ca 2+ The proportion of organic matter further affects the actual degree of harm caused by eosinophilic alkali (EC). Organic matter content reflects soil fertility and structural stability. In saline-alkali soils, organic matter content is often below 1.5 wt%, leading to soil compaction, poor permeability, and exacerbating surface salt accumulation. Organic matter content of 1.5–2.5 wt% can improve aggregate structure and buffer salt stress. Organic matter content >3 wt% can significantly enhance microbial activity, promote salt leaching and nutrient cycling, but requires combined water management for sustained salinity reduction. Alkalinity index (ESP) refers to the percentage of exchangeable sodium ions in the cation exchange capacity, reflecting the risk of sodium toxicity. When ESP >15%, the soil is highly dispersed, becoming muddy when wet and hard when dry, resulting in loss of aeration and permeability. ESP between 5–15% indicates potentially alkalized soil, which is prone to sodium ion activation upon irrigation or rainfall. ESP <5% indicates mild sodium toxicity.

[0126] The results of the above embodiments demonstrate that the nanocomposite fertilizer granules provided by this invention possess both soil improvement and pesticide slow-release functions. This invention uses hydrotalcite (LDH) and / or hydroxyapatite (HAP) as a carrier matrix to load pesticide active ingredients, and combines essential plant nutrients with saline-alkali soil improving substances. This not only achieves the spatiotemporal synergistic release of nutrients and pesticide active ingredients, but also significantly improves soil permeability through the abundant mesoporous-macroporous hierarchical channels in the carrier. Furthermore, combined with saline-alkali soil improving components such as fulvic acid, zinc humic acid, and amino acids, it achieves the improvement of the physicochemical properties of saline-alkali soil and the synergistic enhancement of soil fertility through multiple mechanisms (ion antagonistic regulation, organic matter replenishment, and microstructure reconstruction). Simultaneously, it achieves the triple goals of reduced pesticide application and increased efficiency, simultaneous nutrient supply, and soil ecological restoration, providing an innovative solution to the agricultural bottlenecks of "difficult seedling protection, low fertilizer efficiency, and severe pests and diseases" in saline-alkali land.

[0127] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A nano-composite fertilizer granule with saline-alkali soil improvement and slow-release effects, characterized in that, From the inside out, it includes a compound fertilizer core, a nutrient-enhancing adsorption layer, a nano-formulation slow-release layer, and a fertilizer-pesticide functional coating layer. The core components of the compound fertilizer include essential plant nutrients; The nutrient-enhancing adsorption layer comprises pesticide adsorbent material and saline-alkali soil amendment material. The pesticide adsorbent material includes an adsorbent and pesticide active ingredients loaded in the adsorbent. The adsorbent is biochar. The saline-alkali soil amendment material includes superphosphate, fulvic acid, zinc humic acid, and amino acids. The nutrient-enhancing adsorption layer comprises the following components in parts by weight: 5-10 parts pesticide adsorbent material, 1-5 parts superphosphate, 1-5 parts fulvic acid, 0.5-5 parts zinc humic acid, and 0.5-2 parts amino acids. The components of the nano-formulation sustained-release layer include a nano-sustaining formulation, which comprises a nano-carrier material and a pesticide active ingredient loaded in the nano-carrier material; the nano-carrier material is one or both of hydrotalcite and hydroxyapatite. The functional coating layer of the fertilizer-medicine mixture is composed of one or more of polysaccharides and polyvinyl alcohol. The method for preparing biochar includes: crushing biomass straw and then carbonizing it to obtain biochar; the carbonization temperature is 500~600℃ and the carbonization time is 60~150min; When the nanocarrier material is hydrotalcite, the preparation method of the nano-slow-release formulation includes: mixing sodium hydroxide solution and a mixed aqueous solution of metal salt and pesticide active ingredient for co-precipitation reaction to obtain the nano-slow-release formulation; after the co-precipitation reaction is completed, the resulting reaction solution is allowed to stand for 5-15 minutes, then the pH value of the system is adjusted to 9-10, and then allowed to stand again for 1-5 hours, and then centrifuged. The supernatant obtained by centrifugation is used as the raw material for preparing pesticide adsorbent material. When the nanocarrier material is hydroxyapatite, the preparation method of the nano-slow-release formulation includes: mixing an alcoholic solution of the pesticide active ingredient and an aqueous dispersion of hydroxyapatite for adsorption, followed by solid-liquid separation to obtain the nano-slow-release formulation and a supernatant, the supernatant being used for the preparation of pesticide adsorption materials.

2. The nanocomposite fertilizer granule with saline-alkali soil improvement and slow-release effects according to claim 1, characterized in that, The essential nutrients for plants are one or more of macronutrients, mesonutrients, and micronutrients; the macronutrients are one or more of N, P, and K; the mesonutrients are one or more of Ca, Mg, and S; and the micronutrients are one or more of Fe, Zn, Mn, B, and Cu.

3. The nanocomposite fertilizer granule with saline-alkali soil improvement and slow-release effects according to claim 2, characterized in that, The core of the compound fertilizer comprises the following components by weight: 50-70 parts of macroelements, 1-5 parts of mesoelements, and 1-5 parts of microelements.

4. The nanocomposite fertilizer granule with saline-alkali soil improvement and slow-release effects according to claim 1, characterized in that, The pesticide active ingredients used in the nutrient-enhancing adsorption layer and the nano-formulation slow-release layer are independently one or more of abamectin, emamectin benzoate, dinotefuran, and thiamethoxam; the mass ratio of pesticide active ingredients to nano-carrier materials in the nano-formulation slow-release layer is 1~5:1~5. The hydrotalcite is magnesium aluminum hydrotalcite; the particle size of the nanocarrier material is ≤100nm, and the PDI is <0.

3.

5. The nanocomposite fertilizer granule with saline-alkali soil improvement and slow-release effects according to claim 1, characterized in that, The polysaccharide is one or more of alginate, chitosan, and carboxymethyl cellulose.

6. The nanocomposite fertilizer granule with saline-alkali soil improvement and slow-release effects according to claim 1, characterized in that, The mass ratio of the compound fertilizer core, the nutrient-enhancing adsorption layer, the nano-preparation slow-release layer, and the fertilizer-pesticide functional coating layer is 60~80: 10~25: 2~10: 1~5.

7. The method for preparing the nanocomposite fertilizer granules with saline-alkali soil improvement and slow-release effects according to any one of claims 1 to 6, characterized in that, Includes the following steps: The raw materials for preparing compound fertilizer cores are granulated to obtain compound fertilizer cores; The compound fertilizer core, pesticide adsorption material and saline-alkali soil amendment are granulated to form a nutrient-enhancing adsorption layer on the surface of the compound fertilizer core, thus obtaining composite particles. The composite particles and the nano-sustained-release formulation are mixed and coated to obtain coated particles; The raw materials for preparing the coated granules and the functional coating layer of the fertilizer and pesticide are mixed and coated to obtain the nano-composite fertilizer and pesticide granules with saline-alkali soil improvement and slow-release effects. When the nanocarrier material is hydrotalcite, the preparation method of the nano-sustained-release formulation includes: A sodium hydroxide solution and a mixed aqueous solution of metal salt and pesticide active ingredient were mixed and subjected to a co-precipitation reaction to obtain a nano-sustained-release formulation; When the nanocarrier material is hydroxyapatite, the preparation method of the nano-sustained-release formulation includes: An alcoholic solution of the active pesticide ingredient and an aqueous dispersion of hydroxyapatite were mixed for adsorption, followed by solid-liquid separation to obtain a nano-sustained-release formulation and a supernatant.

8. The preparation method according to claim 7, characterized in that, The metal salts in the mixed aqueous solution of the metal salt and pesticide active ingredient include magnesium salts and aluminum salts; The preparation method of the pesticide adsorbent material includes: mixing the supernatant with an adsorbent for adsorption to obtain the pesticide adsorbent material.

9. The preparation method according to claim 7, characterized in that, The coating temperature is 20~35℃ and the rotation speed is 800~1000rpm.

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