Nano-composite pesticide-fertilizer granules with saline-alkali soil improvement and slow release effects and preparation method of nano-composite pesticide-fertilizer granules

Abstract

The invention relates to the technical field of agricultural environment functional materials and soil improvement, and provides a nano-composite pesticide-fertilizer granule with saline-alkali soil improvement and slow release effects and a preparation method of the nano-composite pesticide-fertilizer granule. The nano-composite pesticide-fertilizer granule provided by the invention sequentially comprises a composite fertilizer core, a nutrition synergistic adsorption layer, a nano-preparation slow-release layer and a pesticide-fertilizer functional coating layer from inside to outside. According to the invention, hydrotalcite and / or hydroxyapatite are / is used as a carrier substrate to load pesticide active components, and meanwhile, plant essential nutrient elements and saline-alkali soil improvement substances are compounded, and the design of a multi-layer structure is combined, so that the synergistic interaction of multiple components is realized; the obtained nano-composite pesticide-fertilizer granules have the functions of soil structure improvement, crop nutrition supply and continuous prevention and control of plant diseases and insect pests; meanwhile, the nano-composite pesticide-fertilizer granules are simple in preparation process, economical, environmentally friendly, suitable for disease and pest control and soil fertility improvement of saline-alkali soil crops and wide in application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural environmental functional materials and soil improvement, and in particular to a nano composite medicinal fertilizer granule with saline-alkali land improvement and slow-release effects and a preparation method thereof. Background Art

[0002] The main characteristic of saline-alkali land is that it contains a large amount of water-soluble salt or alkaline substances. Due to the high salt content and high alkalinity in the soil, the soil organic matter is destroyed and lost, and trace elements are extremely scarce. The soil is sticky when wet and hard when dry. There are often white salt and alkali precipitation on the surface of the soil. The ventilation and water permeability are poor, and the roots of crops are often poisoned, rotten, and die. Even if a large amount of fertilizer is applied, it cannot be absorbed and utilized by crops, resulting in high input and low output. These soils are due to the high water-soluble salt (Na + 、Cl - Excessive accumulation of nutrients (such as phosphates and iodine) and sodium ion enrichment (pH 8.5-10.2) reduce the degradation rate of soil organic matter, reduce the bioavailability of trace elements, and form a dense, compacted soil structure. This "wet, sticky, dry, and hard" degradation not only causes osmotic stress and ion toxicity to crop roots, but also significantly reduces fertilizer utilization, creating a vicious cycle of "fertilization-loss-replenishment."

[0003] Furthermore, traditional methods, which apply pesticides and fertilizers separately, present problems such as low utilization rates, environmental pollution, and high labor costs. Conventional pesticide formulations are susceptible to degradation or leaching, resulting in a short shelf life. Compound fertilizers (such as nitrogen, phosphorus, and potassium) require multiple topdressings to maintain their effectiveness. There are reports on the preparation of compound fertilizers from pesticides and fertilizers, but these typically involve simply mixing the active ingredients of the pesticide and fertilizer. The resulting compound fertilizers lack a sustained-release effect and are ineffective in improving saline-alkali soils. Summary of the Invention

[0004] In view of this, the present invention provides a nano-composite fertilizer granule with saline-alkali land improvement and slow-release effects and a preparation method thereof. The composite fertilizer granule provided by the present invention has both saline-alkali land improvement and slow-release effects and has broad application prospects.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: A nano-composite fertilizer granule with saline-alkali land improvement and slow-release effects, comprising, from the inside out, a compound fertilizer core, a nutrient synergistic adsorption layer, a nano-preparation slow-release layer, and a fertilizer functional coating layer; The ingredients of the compound fertilizer core include essential nutrient elements for plants; The components of the nutrient synergistic adsorption layer include pesticide adsorption materials and saline-alkali soil improvement substances, the pesticide adsorption materials include an adsorbent and a pesticide active ingredient loaded in the adsorbent; the adsorbent includes one or more of biochar, attapulgite, diatomaceous earth and bentonite; the saline-alkali soil improvement substances include one or more of superphosphate, fulvic acid, zinc fulvic acid and amino acids; The components of the nanoformulation sustained-release layer include a nanoformulation sustained-release preparation, which includes a nanocarrier material and a pesticide active ingredient loaded in the nanocarrier material; the nanocarrier material includes one or both of hydrotalcite and hydroxyapatite; The components of the medicine-fertilizer functional coating layer include one or more of polysaccharides and polyvinyl alcohol.

[0006] Preferably, the essential nutrient elements for plants include one or more of macroelements, secondary elements and trace elements; the macroelements include one or more of N, P and K; the secondary elements include one or more of Ca, Mg and S; the trace elements include one or more of Fe, Zn, Mn, B and Cu.

[0007] Preferably, the compound fertilizer core comprises the following components in parts by mass: 50 to 70 parts of macroelements, 1 to 5 parts of secondary elements, and 1 to 5 parts of trace elements.

[0008] Preferably, the nutrient synergistic adsorption layer comprises the following components in parts by mass: 5 to 10 parts of pesticide adsorption material, 1 to 5 parts of superphosphate, 1 to 5 parts of fulvic acid, 0.5 to 5 parts of zinc fulvic acid, and 0.5 to 2 parts of amino acids.

[0009] Preferably, the pesticide active ingredients used in the nutrient synergistic adsorption layer and the nanoformulation sustained-release layer independently include one or more of abamectin, emamectin benzoate, dinotefuran and thiamethoxam; The mass ratio of the pesticide active ingredient to the nanocarrier material in the nanoformulation sustained-release layer is 1-5:1-5; The hydrotalcite is magnesium-aluminum hydrotalcite; the particle size of the nano-carrier material is ≤100 nm, and the PDI is <0.3.

[0010] Preferably, the polysaccharide comprises one or more of alginate, chitosan and carboxymethyl cellulose.

[0011] Preferably, the mass ratio of the compound fertilizer core, the nutrient synergistic adsorption layer, the nanoformulation slow-release layer, and the drug-fertilizer functional coating layer is 60~80: 10~25: 2~10: 1~5.

[0012] The present invention also provides a method for preparing the nano-composite medicinal fertilizer granules with saline-alkali land improvement and slow-release effects as described in the above scheme, comprising the following steps: Granulating the raw materials for preparing the compound fertilizer core to obtain the compound fertilizer core; Granulating the compound fertilizer core, the pesticide adsorption material and the saline-alkali soil improvement material to form a nutrient synergistic adsorption layer on the surface of the compound fertilizer core to obtain composite particles; The composite particles and the nano sustained-release preparation are mixed and coated to obtain coated particles; The coated particles and the raw materials for preparing the medicinal fertilizer functional coating layer are mixed and coated to obtain the nano composite medicinal fertilizer granules with saline-alkali land improvement and slow-release effects; When the nano-carrier material is hydrotalcite, the preparation method of the nano-sustained-release preparation comprises: A sodium hydroxide solution and a mixed aqueous solution of a metal salt and an active ingredient of the pesticide are mixed to perform a coprecipitation reaction to obtain a nano sustained-release preparation; When the nano-carrier material is hydroxyapatite, the preparation method of the nano-sustained-release preparation comprises: The alcohol solution of the pesticide active ingredient and the hydroxyapatite aqueous dispersion are mixed for adsorption, and then solid-liquid separation is performed to obtain a nano sustained-release preparation and a supernatant.

[0013] Preferably, the metal salt in the metal salt-pesticide active ingredient mixed aqueous solution includes magnesium salt and aluminum salt; The preparation method of the pesticide adsorption material comprises: mixing the supernatant with an adsorbent for adsorption to obtain the pesticide adsorption material.

[0014] Preferably, the coating temperature is 20-35° C., and the rotation speed is 800-1000 rpm.

[0015] The present invention provides a nano-composite drug-fertilizer granule with saline-alkali soil improvement and slow-release effects, which comprises, from the inside to the outside, a compound fertilizer core, a nutrient synergistic adsorption layer, a nano-preparation slow-release layer, and a drug-fertilizer functional coating layer; the components of the compound fertilizer core include essential plant nutrients; the components of the nutrient synergistic adsorption layer include pesticide adsorption materials and saline-alkali soil improvement substances; the pesticide adsorption materials include an adsorbent and a pesticide active ingredient loaded in the adsorbent; the adsorbent includes one or more of biochar, attapulgite, diatomaceous earth, and bentonite (which have both soil improvement effects) ); the saline-alkali soil improvement material includes one or more of superphosphate, fulvic acid, zinc fulvic acid and amino acid; the components of the nanoformulation sustained-release layer include nano sustained-release preparations, and the nanoformulation sustained-release preparations include nano carrier materials and pesticide active ingredients loaded in the nano carrier materials; the nano carrier materials include one or two of hydrotalcite (LDH) and hydroxyapatite (HAP); the components of the pesticide-fertilizer functional coating layer include one or more of polysaccharides and polyvinyl alcohol; the pesticide active ingredient used in the nutrient synergistic adsorption layer and the nanoformulation sustained-release layer is thiamethoxam. The nanocomposite pesticide-fertilizer granules provided by the present invention have a four-layer composite system. Through the progressive design of core-adsorption layer-sustained-release layer-coating layer, the precise release and synergistic enhancement of the pesticide and fertilizer components in the soil are achieved; a slow-controlled release technology system is developed based on nanomaterials (hydrotalcite / hydroxyapatite), which overcomes the technical bottlenecks of traditional pesticides that are easily decomposed and ineffective in saline-alkali land and have a short effective period, meets the development needs of pesticide reduction and fertilizer efficiency, and has significant ecological and economic value. Specifically, compared with the prior art, the nanocomposite fertilizer granules of the present invention have the following beneficial effects: Nano-sustained-release preparations are characterized by small size and large specific surface area. The present invention utilizes nanomaterials such as hydrotalcite to intercalate pesticide components, which not only enhances the absorption and conduction of pesticide active ingredients in crops, but also addresses the technical bottleneck of traditional pesticides being easily decomposed and ineffective in saline-alkali soils and having a short duration of effectiveness. By selecting hydrotalcite / hydroxyapatite as a nano-carrier for slow-release pesticides and fertilizers in saline-alkali soils, the nano-carrier can maintain structural integrity in alkaline non-target environments, reducing ineffective release and ecological risks.

[0016] The synergistic effect of multiple components is significant: it has a synergistic combination of saline-alkali land improvement and pesticide and fertilizer functions; the composite fertilizer core can provide essential nutrients for plants, and the nano-formulation slow-release layer can achieve multi-level slow-controlled release of pesticide active ingredients. The two form a "nutrition-plant protection" dual release curve, which meets the needs of crop growth. At the same time, the nutrient synergistic adsorption layer has the dual functions of water conservation and soil improvement and drug slow release, which improves the comprehensive management of saline-alkali land and pest and disease control capabilities; the pesticide and fertilizer functional coating layer can reduce pesticide loss and migration. In summary, the present invention uses hydrotalcite and / or hydroxyapatite as a carrier matrix to load pesticide active ingredients, and at the same time, composites essential plant nutrients and saline-alkali soil improvement materials, combined with a multi-layer structure design, to achieve synergistic effect of multiple components. The resulting nano-composite pesticide and fertilizer granules have the functions of soil structure improvement, crop nutrition supply and continuous pest and disease control, breaking through the limitation of single-function products in traditional technologies that are difficult to achieve synergistic effect.

[0017] The improvement effect of saline-alkali land is significant: the nutrient synergistic adsorption layer of the present invention includes pesticide adsorption materials and saline-alkali soil improvement materials. The adsorbents and saline-alkali soil improvement materials show multi-dimensional synergistic advantages in saline-alkali land improvement. Among them, biochar absorbs salt ions through its porous structure and regulates the soil microenvironment. Attapulgite selectively captures sodium ions and improves soil structure with its nanorod crystals. Diatomaceous earth uses a rigid skeleton to block the upward migration of salt and slowly release nutrients. Fulvic acid, zinc humic acid, amino acids, etc. achieve ecological restoration by chelating salt, promoting aggregate formation, and enhancing crop resistance. The nano-composite fertilizer granules of the present invention can be used to improve coastal saline-alkali soil with a pH value of 7.5-9.1 and an alkalinity of 6.6-72%. It effectively improves the soil aggregate structure and water and fertilizer retention capacity. Through the ion exchange effect of the nutrient synergistic adsorption layer, it reduces soil alkalinity and breaks the vicious cycle of "compaction-barrenness" of saline-alkali land.

[0018] Outstanding pesticide controlled-release performance, enabling multi-stage release: In the sustained-release layer of the nanoformulation, this invention utilizes hydrotalcite and / or hydroxyapatite as nanocarrier materials to load the pesticide active ingredient. To reduce pesticide waste, further improve quality and efficiency, and enhance pesticide loading efficiency, porous materials with both soil-improving and adsorption functions are used to adsorb residual pesticide components, further increasing the pesticide loading rate and achieving multi-stage release. Experimental verification demonstrates 21 days of sustained release of the pesticide active ingredient. The core layer coating technology significantly increases pesticide utilization and reduces application frequency. Furthermore, the nanocarrier material is adaptable to the high pH environment of saline-alkali soil, ensuring the stability of the pesticide active ingredient.

[0019] Environmental advantages: The nano-composite fertilizer granules of the present invention have a utilization rate of nearly 100% of fully biodegradable materials, which is more environmentally friendly. In addition, the granular formulation is convenient for mechanized application, saving labor costs compared to traditional fertilizer and pesticide application.

[0020] The present invention also provides a method for preparing the nano-composite medicinal fertilizer granules with saline-alkali land improvement and slow-release effects as described in the above scheme. The preparation method provided by the present invention prepares the nano-composite medicinal fertilizer granules through granulation and coating processes. No organic solvent is required during the preparation, the operation is simple, and large-scale production is easy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the particle size distribution diagram of the hydrotalcite nano sustained-release preparation prepared in Example 1; Figure 2 This is the SEM image of the hydrotalcite nano sustained-release preparation prepared in Example 1; Figure 3 The release curves of the hydrotalcite nano sustained-release preparations with different carrier contents prepared in Example 2; Figure 4 This is the SEM image of the nano-hydroxyapatite prepared in Example 3; Figure 5 This is a physical picture of the nano-composite medicinal fertilizer granules prepared in Example 7; Figure 6 This is a comparison of the 21-day growth of cabbage in Example 8; Figure 7 This is a comparison of the growth of pepper plants after applying the Chinese medicinal fertilizer in Example 9. DETAILED DESCRIPTION

[0022] The invention provides a nano composite medicinal fertilizer granule with saline-alkali land improvement and slow-release effects, which comprises, from the inside to the outside, a composite fertilizer core, a nutrient synergistic adsorption layer, a nano preparation slow-release layer and a medicinal fertilizer functional coating layer.

[0023] In the present invention, the components of the core of the compound fertilizer include essential plant nutrients; the essential plant nutrients preferably include one or more of macroelements, secondary elements and trace elements; the macroelements are the three core elements with the largest plant growth requirements and must be supplemented in large quantities through fertilizers, secondary elements are essential nutrients that plants require less than macroelements but more than trace elements, generally accounting for 0.01% to 0.1% of the plant's dry weight, and trace elements are elements that plants require in very small quantities but are essential for physiological functions. Specifically, the macroelements include one or more of N, P and K, more preferably including N, P and K at the same time, specifically, the N, P and K are preferably provided by nitrogen fertilizers, phosphate fertilizers and potash fertilizers; the secondary elements include one or more of Ca, Mg and S; and the trace elements include one or more of Fe, Zn, Mn, B and Cu.

[0024] In the present invention, the compound fertilizer core includes the following components in parts by mass: 50 to 70 parts of macroelements, specifically 50 parts, 55 parts, 60 parts or 65 parts, 1 to 5 parts of secondary elements, specifically 1 part, 3 parts or 4 parts, and 1 to 5 parts of trace elements, specifically 1 part, 3 parts or 4 parts; in a specific embodiment of the present invention, the macroelements preferably include 15 to 20 parts of nitrogen fertilizer, 20 to 25 parts of phosphate fertilizer, and 20 to 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 the present invention, the mass parts of the above-mentioned macroelements, secondary elements and trace elements are all calculated based on the mass of each element.

[0025] In the present invention, the components of the nutrient synergistic adsorption layer include pesticide adsorption materials and saline-alkali soil improvement materials, and the pesticide adsorption material includes an adsorbent and a pesticide active ingredient loaded in the adsorbent; the adsorbent includes one or more of biochar, attapulgite, diatomaceous earth and bentonite; the preparation method of the biochar preferably includes: crushing the biomass straw and carbonizing it to obtain biochar; the carbonization temperature is preferably 500~600℃, and the carbonization time is preferably 60~150min; the biomass straw is preferably washed and dried before crushing; the biomass straw preferably includes one or more of rice straw, sorghum straw, corn straw and wheat straw; after the carbonization, the obtained carbonized material is preferably ground and passed through a 200-mesh sieve, and the material under the sieve is taken as the biochar of the present invention.

[0026] In the present invention, the active pesticide ingredients in the nutrient synergistic adsorption layer preferably include one or more of abamectin, emamectin benzoate, dinotefuran and thiamethoxam; the saline-alkali soil improvement substances include one or more of superphosphate, fulvic acid, zinc fulvic acid and amino acids.

[0027] In the present invention, the nutrient synergistic adsorption layer preferably includes the following components in parts by mass: 5 to 10 parts of pesticide adsorption material, specifically 5 parts, 8 parts or 9 parts, 1 to 5 parts of superphosphate, specifically 1 part, 3 parts or 4 parts, 1 to 5 parts of fulvic acid, specifically 1 part, 3 parts or 4 parts, 0.5 to 5 parts of zinc humic acid, specifically 1 part, 3 parts or 4 parts, and 0.5 to 2 parts of amino acids, specifically 0.5 parts, 1 part or 2 parts; the amino acids preferably include one or more of glycine, glutamic acid and aspartic acid.

[0028] In this invention, adsorbents and saline-alkali soil-improving substances demonstrate multi-dimensional synergistic advantages in saline-alkali land improvement. Biochar, through its porous structure, absorbs salt ions and regulates the soil microenvironment. Attapulgite, with its nanorod crystals, selectively captures sodium ions and improves soil structure. Diatomaceous earth, with its rigid skeleton, blocks salt migration and slowly releases nutrients. Fulvic acid, zinc fulvic acid, and amino acids, among others, achieve ecological restoration by chelating salt, promoting aggregate formation, and enhancing crop resistance. By providing a nutrient-enhancing adsorption layer, this invention can extend the release period of pesticides while also effectively improving the soil structure and hydrological function of saline-alkali land.

[0029] In the present invention, the components of the nanoformulation sustained-release layer include a nanoformulation sustained-release preparation, which includes a nanocarrier material and a pesticide active ingredient loaded in the nanocarrier material; the nanocarrier material includes one or both of hydrotalcite and hydroxyapatite; the hydrotalcite is preferably magnesium-aluminum hydrotalcite; the particle size of the nanocarrier material is preferably ≤100 nm, and the PDI is preferably <0.3; the pesticide active ingredient used in the nanoformulation 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 nanocarrier material in the nanoformulation sustained-release layer is preferably 1~5:1~5, specifically 1:1, 0.5:1 or 0.25:1.

[0030] In the present 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, and the risk of non-target exposure is high. Traditional pesticide formulations require frequent application, which can cause resistance and pollution problems. To address this problem, the present invention introduces a nano-preparation sustained-release layer into the nano-composite fertilizer granules, and uses nanomaterials (hydrotalcite and / or hydroxyapatite) to prepare a nano-drug delivery system. The nano-drug delivery system can maintain 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 material used in the present invention is low-cost and has strong penetration and conductivity properties in the crop target body. The controlled-release technology is used to extend the efficacy period and reduce the application frequency and cost.

[0031] In the present invention, the pesticide-fertilizing functional coating layer comprises one or more of a polysaccharide and polyvinyl alcohol; the polysaccharide preferably comprises one or more of alginate, chitosan, and carboxymethyl cellulose; the alginate preferably comprises sodium alginate and calcium alginate. In specific embodiments of the present invention, the pesticide-fertilizing functional coating layer preferably comprises chitosan and alginate (preferably in a 1:1 mass ratio of chitosan to alginate), or carboxymethyl cellulose and alginate, or alginate and polyvinyl alcohol. The present invention reduces pesticide loss and migration by providing the pesticide-fertilizing functional coating layer.

[0032] In the present invention, the mass ratio of the compound fertilizer core, the nutrient synergistic adsorption layer, the nanoformulation slow-release layer, and the drug-fertilizer functional coating layer is preferably 60~80: 10~25: 2~10: 1~5, and more preferably 65~75: 15~20: 3~8: 2~4.

[0033] The nano-composite drug-fertilizer granules provided by the present invention have the functions of improving soil structure, supplying crop nutrition and continuously preventing and controlling pests and diseases. They are suitable for preventing and controlling pests and diseases of crops and improving soil fertility in saline-alkali land. The pH value of the saline-alkali land is 7.5-9.1 and the alkalinity is 6.6-72%.

[0034] The present invention also provides a method for preparing the nano-composite medicinal fertilizer granules with saline-alkali land improvement and slow-release effects as described in the above scheme, comprising the following steps: Granulating the raw materials for preparing the compound fertilizer core to obtain the compound fertilizer core; The compound fertilizer core, the pesticide adsorption material and the saline-alkali soil improvement material are mixed and granulated to form a nutrient synergistic adsorption layer on the surface of the compound fertilizer core to obtain composite particles; mixing the composite particles, the nano sustained-release preparation and water for coating to obtain coated particles; The coated particles and the raw materials for preparing the medicinal fertilizer functional coating layer are mixed and coated to obtain the nano composite medicinal fertilizer granules with saline-alkali land improvement and slow-release effects.

[0035] The present invention granulates the raw materials for preparing the compound fertilizer core (referred to as the first granulation) to obtain the compound fertilizer core. In the present invention, the raw materials for preparing the compound fertilizer core specifically include raw materials that provide macroelements, secondary elements, and trace elements. The raw materials that provide macroelements preferably include one or more of urea, monoammonium phosphate, and potassium sulfate. The present invention has no particular requirements for the raw materials that provide the secondary and trace elements; those familiar to those skilled in the art can be used. Specifically, well-known secondary and trace element fertilizers can be used, selected based on the elements required in the compound fertilizer. Prior to the first granulation, the raw materials for preparing the compound fertilizer core are preferably ground and sieved, and then the sieved raw materials are uniformly mixed. The mesh size of the sieve used for sieving is preferably 50-100 mesh. The first granulation is preferably performed by roller humidification granulation, preferably in a drum granulator. In a specific embodiment of the present invention, the uniformly mixed raw materials are preferably added to the drum granulator, and then atomized water is introduced for rolling humidification granulation. The particle size of the compound fertilizer core is preferably 2-3 mm.

[0036] After obtaining the composite fertilizer core, the present invention mixes the composite fertilizer core, the pesticide adsorbent material, and the saline-alkali soil improving material and performs granulation (referred to as the second granulation), forming a nutrient synergistic adsorption layer on the surface of the composite fertilizer core to obtain composite particles. In the present invention, the method for preparing the pesticide adsorbent preferably includes: mixing the supernatant (the supernatant remaining from preparing the hydroxyapatite nano-sustained-release formulation, which will be described in detail later) with an adsorbent for adsorption (referred to as the first adsorption) to obtain the pesticide adsorbent; 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 first adsorption time is preferably 2-6 hours, and the first adsorption is preferably performed under stirring; after the first adsorption is completed, the resulting pesticide adsorbent is preferably filtered and dried.

[0037] In the present invention, the conditions for the second granulation are preferably the same as those for the first granulation. In a specific embodiment of the present invention, after the first granulation is completed, the mixture of the pesticide adsorbent material and the saline-alkali soil improving material is preferably added to a drum granulator to continue the second granulation. After the second granulation is completed, the resulting composite granules are preferably removed and dried.

[0038] After obtaining the composite particles, the present invention mixes the composite particles and the nano sustained-release preparation and coats them to obtain coated particles. In the present invention, when the nano carrier material is hydrotalcite, the preparation method of the nano sustained-release preparation (referred to as hydrotalcite nano sustained-release preparation) includes: mixing a sodium hydroxide solution and a metal salt-pesticide active ingredient mixed aqueous solution for coprecipitation reaction to obtain a nano sustained-release preparation; the concentration of the sodium hydroxide solution is preferably 0.2wt%~2wt%, specifically 0.5wt% or 2wt%; the metal salt in the metal salt-pesticide active ingredient mixed aqueous solution preferably includes magnesium salt and aluminum salt, specifically magnesium nitrate and aluminum nitrate; the preparation method of the metal salt-pesticide active ingredient mixed aqueous solution preferably includes: mixing magnesium salt, aluminum salt, pesticide technical and water to obtain a metal salt-pesticide active ingredient mixed aqueous solution; the total mass fraction of magnesium salt and aluminum salt in the metal salt-pesticide active ingredient mixed aqueous solution is preferably 1wt%~5wt%, specifically 2wt% or 3wt%; the molar ratio of the magnesium salt to the 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 metal salt-pesticide active ingredient mixed aqueous solution is 1wt%-5wt%, specifically 2wt% or 3wt%; the volume ratio of the sodium hydroxide solution to the metal salt-pesticide active ingredient mixed aqueous solution is preferably 0.5:1-1:1; the coprecipitation reaction is preferably carried out under shear conditions, and the shear time is preferably 5-20min; after the shearing is completed, the obtained reaction solution is preferably allowed to stand for 5-15min, and then the pH value of the system is adjusted to 9-10, and then allowed to stand again for 1-5h, and then centrifuged to separate, and the obtained lower precipitate is the hydrotalcite nano sustained-release preparation; the supernatant obtained by the centrifugation is preferably used as a raw material for preparing a pesticide adsorption material.

[0039] In the present invention, when the nano-carrier material is hydroxyapatite, the preparation method of the nano-sustained-release preparation (denoted as hydroxyapatite nano-sustained-release preparation) comprises: mixing an alcohol solution of the pesticide active ingredient and a hydroxyapatite aqueous dispersion for adsorption (denoted as the second adsorption), and then performing solid-liquid separation to obtain a nano-sustained-release preparation and a supernatant; the preparation method of the alcohol solution containing the pesticide active ingredient preferably comprises: dissolving the pesticide raw material with alcohol to obtain the alcohol solution containing the pesticide active ingredient; the alcohol is preferably methanol or ethanol; the content of the pesticide active ingredient in the alcohol solution is preferably 1wt%~5wt%; the concentration of the hydroxyapatite aqueous dispersion is preferably 1wt%~5wt%; the preparation method of the nano-hydroxyapatite is preferably a chemical co-precipitation method, a sol-gel method, a water-soluble solid-phase method, a precipitate ... A thermal method, a microwave synthesis method or a combustion method, more preferably a chemical coprecipitation method; the chemical coprecipitation method specifically comprises the following steps: dropwise adding a diammonium hydrogen phosphate solution into a calcium nitrate solution to carry out a coprecipitation reaction to obtain the hydroxyapatite, specifically nano-hydroxyapatite; the concentration of the diammonium hydrogen phosphate solution is preferably 0.5-1g / 100mL, more preferably 0.79g / 100mL, and the pH value of the diammonium hydrogen phosphate solution is preferably 10; the concentration of the calcium nitrate solution is preferably 2-2.5g / 100mL, more preferably 2.36g / 100mL, and the pH value of the calcium nitrate solution is preferably 10; the temperature of the system during the dropwise addition is preferably 40°C, and after the dropwise addition is completed, the mixture is preferably stirred for 40 minutes, then aged for 12 hours, and then the obtained solid product is washed.

[0040] In the present 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 sustained-release preparation, and the remaining filtrate is the supernatant, which is used in the preparation of the pesticide adsorption material.

[0041] In the present 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°C, specifically 25°C or 30°C, and the rotation speed is preferably 800~1000rpm, specifically 850rpm or 900rpm.

[0042] After obtaining the coated granules, the present invention mixes the coated granules with the raw materials for preparing the medicinal fertilizer functional coating layer and performs coating, thereby obtaining the nanocomposite medicinal fertilizer granules with saline-alkali land improvement and sustained-release effects. In the present invention, the raw materials for preparing the medicinal fertilizer functional coating layer are specifically one or more of polysaccharides and polyvinyl alcohol, the types of which are not further described herein; the coating conditions are the same as those for the coating described above.

[0043] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] The parts in the following examples are all parts by mass.

[0045] Example 1 Preparation of a hydrotalcite nano sustained-release preparation: Magnesium nitrate, aluminum nitrate (the molar ratio of magnesium to aluminum is 1.3:1, and the total mass of magnesium nitrate and aluminum nitrate is 5.5 g), 3 g of thiamethoxam technical, and 250 mL of water are mixed to obtain a mixed aqueous solution; a sodium hydroxide solution having a concentration of 1.1 g / 100 mL is prepared; the sodium hydroxide solution is added to the mixed aqueous solution, sheared for 5 minutes, allowed to stand for 15 minutes, adjusted to a pH of 10, allowed to stand for 40 minutes, and then centrifuged to wash the precipitate to obtain a hydrotalcite nano sustained-release preparation and a supernatant.

[0046] Particle size distribution measurement: The prepared hydrotalcite nano sustained-release preparation was diluted to 0.5% (w / w), ultrasonically vibrated and uniformly mixed, and the hydrated particle size and PDI of the hydrotalcite nano sustained-release preparation were measured using a Malvern particle size analyzer at room temperature. Each sample was measured in parallel 3 times, and the average value was taken and the standard deviation was calculated. The test results are as follows: Figure 1 shown. Figure 1 The results in the literature show that the hydrotalcite nano sustained-release preparation prepared by the present invention has a small particle size of about 70 nm, a PDI of 0.18, and good dispersibility.

[0047] Electron microscopy morphology characterization: First, the prepared hydrotalcite nano-sustained-release preparation was diluted to an appropriate concentration, 5 μL of the solution was evenly dropped on the smooth surface of a silicon wafer, and allowed to dry at room temperature to obtain an observation sample. The morphology of the prepared hydrotalcite nano-sustained-release preparation was characterized by SEM at an accelerating voltage of 3 kV. The test results are shown in Figure 2. Figure 2 shown; according to Figure 2 It can be seen that the hydrotalcite nano sustained-release preparation prepared in the present invention has a hexagonal structure with regular morphology and smooth surface.

[0048] Example 2 According to the preparation method of Example 1, the carrier ratio was changed to prepare hydrotalcite nano sustained-release preparations with different carrier ratios. Specifically, the addition ratio of magnesium nitrate / aluminum nitrate and thiamethoxam original drug was adjusted to prepare three thiamethoxam nano drug delivery systems Y1, Y2 and Y3 with different hydrotalcite carrier ratios. The mass ratios of thiamethoxam and hydrotalcite in the obtained hydrotalcite nano sustained-release preparations were 1:1, 0.5:1 and 0.25:1, respectively.

[0049] Characterization of sustained-release performance: In order to evaluate the in vitro release of the nano-sustained-release preparation, the cumulative release of thiamethoxam at different times was determined by dialysis in this example. The specific operation was as follows: a 50% volume fraction methanol aqueous solution was used as the in vitro simulated release medium, and 10 mg of the thiamethoxam active ingredient of the hydrotalcite nano-sustained-release preparation samples with three different carrier ratios were accurately weighed, dissolved in 5 mL of 50% methanol, placed in a treated dialysis bag (8000Da), and suspended in a brown reagent bottle containing 95 mL of 50% methanol solution. The samples were placed in a constant temperature shaking incubator at 25°C and shaken at regular intervals (see the specific interval time). Figure 3 ), remove 2 mL of the release solution from the brown reagent bottle and add 2 mL of fresh 50% methanol-water solution to ensure that the reaction bottle still contains 100 mL after sampling. The release solution is then diluted to a certain extent and the thiamethoxam concentration is determined by high-performance liquid chromatography to calculate the cumulative release of thiamethoxam.

[0050] The test results are as follows Figure 3 As shown. Figure 3 It can be seen that the hydrotalcite nano-sustained-release preparations with different carrier ratios all have a sustained-release effect, wherein the higher the carrier ratio, the slower the release of the pesticide active ingredient and the stronger the sustained-release performance.

[0051] Example 3 Preparation of nanohydroxyapatite: Prepare 2.36 g / 100 mL of calcium nitrate tetrahydrate solution with a pH of 10 and 0.79 g / 100 mL of diammonium hydrogen phosphate solution with a pH of 10; slowly add the diammonium hydrogen phosphate solution dropwise to the calcium nitrate tetrahydrate solution, maintain the reaction system temperature at 40°C, stir for 40 minutes, and then continue aging for 12 hours. Wash the precipitate to obtain nanohydroxyapatite powder.

[0052] Figure 4 This is the SEM image of the nano-hydroxyapatite prepared in this example.

[0053] Example 4 Preparation of a hydroxyapatite nano-sustained-release preparation: The nano-hydroxyapatite powder prepared in Example 3 was mixed with deionized water in a mass ratio of 1:100 to obtain a dispersion. A 1 wt % alcohol solution of the technical pesticide thiamethoxam was then added to the dispersion. The mixture was sheared for 10 minutes, stirred for 4 hours, and centrifuged to obtain a hydroxyapatite nano-sustained-release preparation.

[0054] Example 5 Preparation of biochar: Wash and dry rice straw, crush it, and then carbonize it in a carbonization furnace at a temperature of 500°C for 120 minutes. Finally, grind and sieve it to obtain biochar.

[0055] Example 6 Preparation of pesticide adsorption material (biochar loaded with thiamethoxam): The supernatant remaining after centrifugation in Example 1 was mixed with the biochar prepared in Example 5 at a mass ratio of 20:1, ultrasonicated for 15 minutes, stirred for 2 hours, filtered, and the resulting solid product was dried to obtain biochar loaded with thiamethoxam.

[0056] Example 7 Preparation of nanocomposite fertilizer granules with saline-alkali land improvement and slow-release effects: 20 parts of nitrogen fertilizer (urea), 25 parts of phosphate fertilizer (monoammonium phosphate), 25 parts of potash fertilizer (potassium sulfate), 4 parts of secondary element fertilizer (containing Ca and Mg), and 1 part of trace element fertilizer (containing Fe, Zn, and B) are ground separately and passed through a 50-mesh sieve. The sieved materials are then mixed uniformly and transferred to a rotary drum granulator with atomized water for rolling humidification and granulation. The granules have a particle size of 2-3 mm, thereby obtaining a composite fertilizer core. The sieved and uniformly mixed raw materials for preparing the nutrient synergistic adsorption layer (5 parts of thiamethoxam-loaded biochar prepared in Example 6, 4 parts of superphosphate, 5 parts of fulvic acid, 3 parts of zinc fulvic acid, and 1 part of amino acids (specifically glycine and glutamic acid)) are then added, and granulation is continued. Finally, the prepared granules are removed and dried to obtain composite granules.

[0057] A small water chestnut-type coating machine was used to evenly coat 4 parts of the hydrotalcite nano-sustained-release preparation prepared in Example 1 on the surface of the composite particles (93 parts). During the coating process, atomized water was sprayed appropriately to ensure the viscosity of the particles. Finally, chitosan-alginate (3 parts, the mass ratio of chitosan to alginate was 1:1) was used for coating to obtain nano-composite medicinal fertilizer granules with saline-alkali land improvement and sustained-release effects. The actual picture of the obtained nano-composite medicinal fertilizer granules is shown in FIG. Figure 5 shown.

[0058] pH Determination: The pH of the nanocomposite fertilizer granules prepared in Example 7 was determined according to the "Determination of pH Value of Pesticides" (GB / T 1601-1993). The specific procedure was as follows: First, 10 g of sample was weighed into a 200 mL beaker, 100 mL of water was added, and the mixture was vigorously stirred for 1 minute. The mixture was then allowed to stand for 1 minute. The pH meter was then calibrated and the pH measured. The measurement was repeated three times and the average value was calculated (GB / T 1601-1993). The pH of the nanocomposite fertilizer granules was 6.5, indicating that its pH met national standards.

[0059] The moisture content of the nanocomposite fertilizer granules prepared in Example 7 was determined according to the "Determination of free water content in compound fertilizers - Vacuum oven method" (GB / T8576-2010). 20 g of thiamethoxam nanocomposite fertilizer granules were accurately weighed and placed at 50 ° C ± 2 ° C with a vacuum degree of 6.4 × 10 4 Pa~7.1×104 The granules were dried in an electric constant temperature vacuum drying oven at 1000 Pa for 2 h, cooled to room temperature in a desiccator, and weighed. The measurement was repeated three times and the average value was obtained. The results showed that the water content of the nanocomposite fertilizer granules prepared by the present invention was 3.2%, which meets national regulations, indicating that the prepared nanocomposite fertilizer granules have good quality and storage potential.

[0060] The nanocomposite fertilizer granules prepared in Example 7 were subjected to thermal storage stability testing: The thermal storage stability of the nanocomposite fertilizer granules was evaluated according to GB / T 19136-2003, "Method for Determination of Thermal Storage Stability of Pesticides." Specifically, a 20g sample was placed in a glass dish to form a smooth, even layer. Three parallel plates were then stored at 54±2°C for 14 days. The sample was then removed and placed in a drying oven to cool to room temperature. The drug content was then determined within 24 hours. The results showed that the decomposition rate of thiamethoxam in the nanocomposite fertilizer granules was 4.6%, demonstrating a relatively low decomposition rate. According to the "Method for Determination of Thermal Storage Stability of Pesticides" (GB / T 19136-2003), the nanocomposite fertilizer granules prepared by the present invention exhibited good chemical stability under thermal storage conditions.

[0061] Example 8 This example verifies the effect of nanocomposite fertilizer granules with saline-alkali land improvement and slow-release effects on the control and growth of cabbage aphids. The specific experimental steps are as follows: This example used a cabbage planting experiment using pots measuring (L x W x H: 15 cm x 15 cm x 15 cm). Each pot was filled with 1.0 kg of garden soil. The cabbage was sown and transplanted when it reached two true leaves, retaining one plant per pot. During this period, the plants were watered every three days, using approximately 250 mL of water each time. When the plants reached the fifth true leaf stage, different compositions of fertilizer were applied.

[0062] The uninoculated group received four treatments: Treatment 1: no fertilizer; Treatment 2: Only the thiamethoxam nanopesticide with sustained-release effect (the hydrotalcite nano-sustaining-release preparation prepared in Example 1) was applied; Treatment 3: NPK application only; Treatment 4: applying the nano-composite fertilizer granules with saline-alkali land improvement and slow-release effects prepared in Example 7.

[0063] Spray once every 3 days for 3 consecutive times, with 5 replicates for each treatment.

[0064] The inoculated groups were subjected to two treatments: Treatment 6 (control): no pesticide or fertilizer application; Treatment 7: Apply the nano-composite fertilizer granules with saline-alkali land improvement and slow-release effects prepared in Example 7.

[0065] Cabbage aphids (wingless adult aphids) purified and cultured in the laboratory were inoculated with 30 aphids per cabbage plant (evenly transferred to the back of the leaves with a soft brush). The control effect and cabbage growth were investigated 3, 5, 7, 14, and 21 days after the application of the fertilizer. The results are shown in Table 1 and Figure 6 Control efficacy = (1 - number of live insects in the treatment group / number of live insects in the control group) × 100%.

[0066] Table 1 Cabbage aphid control effect after applying pesticide fertilizer

[0067] It can be seen from the data in Table 1 that after applying the nanocomposite fertilizer granules of the present invention, a high control effect can be maintained from 3 to 21 days, and it has a certain slow-release performance; and according to Figure 6 It can be seen that the cabbage growth in the experimental group using the nano-composite fertilizer granules of the present invention is significantly better than that in the other experimental groups.

[0068] Example 9 This example tests the effects of nanocomposite fertilizer granules with saline-alkali land improvement and slow-release effects on pepper growth and saline-alkali land improvement in different regions. The specific experimental steps are as follows: In this example, a pepper planting experiment was conducted using pots measuring 8 cm (length x width x height) x 8 cm (height x width) x 6 cm. Each pot was filled with 250 g of soil (different types of saline-alkali soil from coastal areas). The peppers were sown and transplanted when they had two true leaves. One plant was retained per pot. During this period, the peppers were watered every three days with approximately 100 mL of water each time.

[0069] Four treatments are performed separately: Control group: Binzhou saline-alkali soil No. 1, no fertilizer; Treatment 1: Binzhou saline-alkali soil No. 1, mixed before sowing; Treatment 2: Dongying saline-alkali soil No. 1, mixed before sowing; Treatment 3: Dongying saline-alkali soil No. 2, mixed before sowing; Treatment 4: Dongying saline-alkali soil No. 3, mixed before sowing; The applied fertilizers were all the nanocomposite fertilizer granules prepared in Example 7. The soil pH, organic matter, electrical conductivity, and alkalinity (CEC) were tested before and 21 days after the application of the fertilizers. Soil-related indicator testing methods: pH was measured using a Leici PHS-3C pH meter using the standard method "NY / T 1377-2007 Determination of pH in Soil"; organic matter was measured using a fully automatic organic matter analyzer JX-S7066 using the standard method "NY / T 1121.6-2006 Soil Testing Part 6: Determination of Soil Organic Carbon and Organic Matter"; conductivity was measured using a conductivity meter using the method "HJ 802-2016"; alkalinity was measured using a Tianbo 50ml burette and an Agilent Technologies 5110 ICP-OES according to Section 3.4 "Determination of Exchangeable Soil and Calculation of Alkalinity" in the "Methods for Agricultural Chemical Analysis of Soils"; CEC was measured using a Tianbo 50ml burette using the EDTA-ammonium acetate exchange method in the "Technical Specifications for Soil Analysis" (Second Edition).

[0070] The test results are shown in Table 2; Figure 7 Comparison of the growth of pepper plants after application of pesticide and fertilizer.

[0071] Table 2 Changes in soil indicators of different types before and after application of pesticide fertilizers in saline-alkali soils in different regions

[0072] As shown in Table 2, the application of pesticides and fertilizers showed significant results: the pH, electrical conductivity, and alkalinity of the saline-alkali soil were significantly improved, indicating that these treatments are effective in improving saline-alkali soil. Freshwater irrigation in the control group also improved soil parameters, but the effect was not as significant as in the treatment group.

[0073] The pH value of saline-alkali soil reflects the acidity and alkalinity of the soil and is an important indicator for measuring salinization. pH>8.5 indicates that the soil is highly alkaline. At this time, the sodium ions in the soil colloids increase significantly, resulting in a decrease in the effectiveness of nutrients (such as phosphorus and iron); pH between 7.5-8.5 is slightly alkaline, 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 (about 40 mS / cm), the soil is severely salinized, and most crops experience osmotic stress and ion poisoning; EC of 2-4 dS / m is moderately saline, and salt-tolerant plants can still grow; EC<2 dS / m has little effect on salt, and the salt composition (such as Na + / Ca 2+The proportion of organic matter will further affect the actual degree of EC damage. The organic matter content reflects soil fertility and structural stability. The organic matter content of saline-alkali soil is often less than 1.5wt%, which leads to soil compaction and poor permeability, exacerbating salt-alkali surface accumulation. When the organic matter content is 1.5-2.5wt%, it can improve aggregate structure and buffer saline-alkali stress. Organic matter content greater than 3wt% can significantly enhance microbial activity, promote salt leaching and nutrient recycling, but requires water management to continuously reduce salinity. Alkalinity (ESP) refers to the percentage of exchangeable sodium ions in the cation exchange capacity and reflects the risk of sodium toxicity. When ESP is greater than 15%, the soil is highly dispersible, muddy when wet, hard when dry, and loses air and water permeability. ESP of 5-15% is potentially alkaline soil, and sodium ion activation is easily caused by irrigation or precipitation. When ESP is less than 5%, the sodium damage is mild.

[0074] The results of the above examples demonstrate that the nanocomposite pesticide-fertilizer granules provided by the present invention combine soil improvement and pesticide sustained-release functions. Using hydrotalcite (LDH) and / or hydroxyapatite (HAP) as a carrier matrix to load the pesticide active ingredient, and combining essential plant nutrients with saline-alkali soil-improving substances, this method not only achieves the spatiotemporal coordinated release of the nutrients and the pesticide active ingredient, but also significantly improves soil permeability through the abundant mesoporous-macroporous hierarchical channels in the carrier. Furthermore, by combining saline-alkali soil-improving components such as fulvic acid, zinc fulvic acid, and amino acids, the granules improve the physical and chemical properties of saline-alkali soils and enhance soil fertility through multiple mechanisms of action (ion antagonism regulation, organic matter supplementation, and microstructural reconstruction). This simultaneously achieves the triple goals of pesticide reduction and efficiency, nutrient supply, and soil ecological restoration, providing an innovative solution to the agricultural bottlenecks of saline-alkali land: difficulty in maintaining seedlings, low fertilizer efficiency, and high levels of pests and diseases.

[0075] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A nanocomposite fertilizer granule with saline-alkali land improvement and slow-release effect, characterized in that: From the inside to the outside, it includes the compound fertilizer core, the nutrient synergistic adsorption layer, the nano-preparation slow-release layer and the fertilizer functional coating layer; The ingredients of the compound fertilizer core include essential nutrient elements for plants; The components of the nutrient synergistic adsorption layer include pesticide adsorption materials and saline-alkali soil improvement substances, the pesticide adsorption materials include an adsorbent and a pesticide active ingredient loaded in the adsorbent; the adsorbent includes one or more of biochar, attapulgite, diatomaceous earth and bentonite; the saline-alkali soil improvement substances include one or more of superphosphate, fulvic acid, zinc fulvic acid and amino acids; The components of the nanoformulation sustained-release layer include a nanoformulation sustained-release preparation, which includes a nanocarrier material and a pesticide active ingredient loaded in the nanocarrier material; the nanocarrier material includes one or both of hydrotalcite and hydroxyapatite; The components of the medicine-fertilizer functional coating layer include one or more of polysaccharides and polyvinyl alcohol.

2. The nanocomposite medicinal fertilizer granules with saline-alkali land improvement and slow-release effects according to claim 1, characterized in that: The essential nutrient elements for plants include one or more of macroelements, secondary elements and trace elements; the macroelements include one or more of N, P and K; the secondary elements include one or more of Ca, Mg and S; and the trace elements include one or more of Fe, Zn, Mn, B and Cu.

3. The nanocomposite medicinal fertilizer granules with saline-alkali land improvement and slow-release effects according to claim 2, characterized in that: The compound fertilizer core comprises the following components in parts by mass: 50-70 parts of macroelements, 1-5 parts of secondary elements, and 1-5 parts of trace elements.

4. The nanocomposite medicinal fertilizer granules with saline-alkali land improvement and slow-release effects according to claim 1, characterized in that: The nutrient synergistic adsorption layer comprises the following components in parts by mass: 5-10 parts of pesticide adsorption material, 1-5 parts of superphosphate, 1-5 parts of fulvic acid, 0.5-5 parts of zinc fulvic acid, and 0.5-2 parts of amino acids.

5. The nanocomposite medicinal fertilizer granules with saline-alkali land improvement and slow-release effects according to claim 1, characterized in that: The pesticide active ingredients used in the nutrient synergistic adsorption layer and the nano-preparation sustained-release layer independently include 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-preparation sustained-release layer is 1-5:1-5; The hydrotalcite is magnesium-aluminum hydrotalcite; the particle size of the nano-carrier material is ≤100 nm, and the PDI is <0.

3.

6. The nanocomposite medicinal fertilizer granules with saline-alkali land improvement and slow-release effects according to claim 1, characterized in that: The polysaccharide includes one or more of alginate, chitosan and carboxymethyl cellulose.

7. The nanocomposite medicinal fertilizer granules with saline-alkali land improvement and slow-release effects according to claim 1, characterized in that: The mass ratio of the compound fertilizer core, the nutrient synergistic adsorption layer, the nano-preparation slow-release layer, and the drug-fertilizer functional coating layer is 60-80: 10-25: 2-10: 1-5.

8. The method for preparing the nanocomposite medicinal fertilizer granules with saline-alkali land improvement and slow-release effects according to any one of claims 1 to 7, characterized in that: The following steps are involved: Granulating the raw materials for preparing the compound fertilizer core to obtain the compound fertilizer core; Granulating the compound fertilizer core, the pesticide adsorption material and the saline-alkali soil improvement material to form a nutrient synergistic adsorption layer on the surface of the compound fertilizer core to obtain composite particles; The composite particles and the nano sustained-release preparation are mixed and coated to obtain coated particles; The coated particles and the raw materials for preparing the medicinal fertilizer functional coating layer are mixed and coated to obtain the nano composite medicinal fertilizer granules with saline-alkali land improvement and slow-release effects; When the nano-carrier material is hydrotalcite, the preparation method of the nano-sustained-release preparation comprises: A sodium hydroxide solution and a mixed aqueous solution of a metal salt and an active ingredient of the pesticide are mixed to perform a coprecipitation reaction to obtain a nano sustained-release preparation; When the nano-carrier material is hydroxyapatite, the preparation method of the nano-sustained-release preparation comprises: The alcohol solution of the pesticide active ingredient and the hydroxyapatite aqueous dispersion are mixed for adsorption, and then solid-liquid separation is performed to obtain a nano sustained-release preparation and a supernatant.

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

10. The preparation method according to claim 8, characterized in that The coating temperature is 20-35° C., and the rotation speed is 800-1000 rpm.

Images