Fruit tree trace element compound fertilizer based on nano-chelating technology and application of fruit tree trace element compound fertilizer

Abstract

The invention relates to a fruit tree trace element compound fertilizer based on a nano-chelating technology and application thereof, and belongs to the technical field of fertilizers. The preparation method comprises the following steps: mixing a zinc element compound, an iron element compound, a manganese element compound, a boron element compound, a copper element compound, a molybdenum element compound and a phytic acid chelating agent, adding into water, and stirring until a uniform solution is formed; heating and stirring the mixed solution for reaction; and after the reaction is finished, drying the product into powder by adopting spray drying, thereby obtaining the nano-scale fruit tree trace element compound fertilizer. The phytic acid chelating agent is prepared from phytic acid, ethanol, citric acid, imidazolinone malonic acid and epoxy linseed oil; the nano fruit tree microelement compound fertilizer prepared by the invention can obviously reduce the fruit cracking rate of fruit trees, improve the fruit shape regularity and improve the fruit hardness, has good yield-increasing and quality-improving effects on the fruit trees, and has good application prospects in the field of fruit tree planting.

Description

Technical Field

[0001] The present invention relates to the technical field of fertilizers, in particular to a nano-chelation technology-based trace element compound fertilizer for fruit trees and application thereof. Background Art

[0002] Fruit trees require a variety of nutrients for growth and development. In addition to macronutrients like nitrogen, phosphorus, and potassium, trace elements like zinc, iron, manganese, boron, copper, and molybdenum also play crucial roles. For example, zinc is a catalyst for auxin synthesis, and zinc deficiency can lead to small leaf disease in fruit trees. Iron is essential for photosynthesis and respiration, and iron deficiency can cause chlorosis in fruit trees. Boron, which plays a crucial role in pollen germination and pollen tube elongation, can lead to severe flower and fruit drop, as well as fruit deformities.

[0003] Patent CN1078711A discloses a long-acting inorganic composite trace element fertilizer, a glassy plant micronutrient fertilizer. It uses borate glass as its base glass. The fertilizer's chemical composition is: 13-32% B2O3, 22-40% SiO2, 2-8% Al2O3, 5-11% K2O+Na2O, and 4-12% MgO+CaO. Trace element metal oxides (excluding B2O3) account for 0-36% of the total glassy composition. The fertilizer is manufactured by melting various weighed and mixed fertilizer raw materials in a furnace at a temperature of 1100-1280°C, quenching with water, drying, and grinding.

[0004] Patent CN1069482A discloses a method for producing a rare earth fertilizer, in particular, a method for producing a special rare earth fertilizer using 2-deoxy, 2-amino, (1→4)D-glucan (hereinafter referred to as CT) as an active chelating agent.

[0005] Trace element fertilizers produced using existing technologies have numerous drawbacks. Firstly, trace elements in the form of inorganic salts are easily fixed in the soil, becoming insoluble and losing their effectiveness, severely impacting their fertilizing efficiency. Secondly, the trace elements in conventional fertilizers are difficult for fruit trees to absorb efficiently, resulting in low fertilizer utilization, significant waste, and potentially causing environmental problems such as soil pollution. Therefore, developing a fertilizer that can improve trace element utilization and effectively meet the growth needs of fruit trees is of great practical significance. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a trace element compound fertilizer for fruit trees based on nano-chelation technology, which is characterized by being prepared from the following raw materials in parts by weight: 5-10 parts of zinc compound, 3-8 parts of iron compound, 3-7 parts of manganese compound, 2-6 parts of boron compound, 1-4 parts of copper compound, 0.5-3 parts of molybdenum compound, and 10-20 parts of phytic acid chelating agent.

[0007] As a preferred embodiment of the present invention, the zinc compound is zinc sulfate or zinc oxide; the iron compound is ferrous sulfate or ferric citrate; the manganese compound is manganese sulfate or manganese chloride; the boron compound is borax or boric acid; the copper compound is copper sulfate or copper oxide; and the molybdenum compound is sodium molybdate or ammonium molybdate.

[0008] As a preferred embodiment of the present invention, the preparation method of the trace element compound fertilizer for fruit trees is as follows:

[0009] S1: Mix a zinc compound, an iron compound, a manganese compound, a boron compound, a copper compound, a molybdenum compound, and a phytic acid chelating agent in parts by weight, add the mixture to 120-180 parts of water, and stir until a uniform solution is formed;

[0010] S2: Heat the mixed solution to 50-80°C, adjust the pH to 4-6, and stir the mixture for 2-4 hours;

[0011] S3: After the reaction is completed, the product is dried into powder by spray drying to obtain a nano-scale trace element compound fertilizer for fruit trees.

[0012] As a preferred embodiment of the present invention, the preparation method of the phytic acid chelating agent is:

[0013] A1: Add 10-20 parts of phytic acid to a reactor, add 130-160 parts of ethanol and stir to dissolve, heat to 50-60°C, add 0.1-1 parts of citric acid catalyst, and stir for 10-15 minutes to activate the system;

[0014] A2: Slowly add 5-15 parts of imidazolidinonemalonic acid while stirring, controlling the addition time to 3-6 hours. After the addition is complete, maintain the temperature at 50-60°C and stir for 2-3 hours. Raise the temperature to 70-90°C and slowly add 20-40 parts of epoxy linseed oil. After the addition is complete, maintain the temperature at 70-90°C and stir for 3-5 hours.

[0015] A3: After the reaction is completed, the mixture is cooled to room temperature and ethanol, unreacted arginine and epoxy linseed oil are removed by distillation under reduced pressure to obtain a phytic acid chelating agent.

[0016] As a preferred embodiment of the present invention, the nano-scale trace element compound fertilizer for fruit trees is used in fruit tree planting, and root topdressing is performed during the flower bud differentiation period, young fruit period and swelling period of the fruit trees, with the root topdressing dosage being 5-15 kg per mu.

[0017] Reaction mechanism:

[0018] Citric acid acts as a proton donor and reacts with the phosphate group of phytic acid to generate a protonated phytic acid active intermediate, thereby enhancing its electrophilicity; the carboxyl group and imino group of imidazolinonemalonic acid react with the phosphate group of phytic acid through nucleophilic substitution to form ester bonds and ionic bonds.

[0019] The epoxy group of epoxidized linseed oil is ring-opened and undergoes polymerization reaction with the amino group (-NH-) and carboxyl group of imidazolidinonemalonic acid to form a three-dimensional network structure.

[0020] Technical effect:

[0021] 1. Improve fertilizer utilization and effectiveness: Nano-chelation technology improves the utilization rate of trace elements, avoids them being fixed in the soil or lost through leaching, and allows them to be directly absorbed by the roots of fruit trees, solving the problem of traditional fertilizers being easily ineffective.

[0022] 2. Promote the growth of fruit trees and improve the quality of fruit: meet the trace element needs of fruit trees at all stages, zinc, iron, manganese, etc. work synergistically to enhance photosynthesis, prevent chlorosis, improve nitrogen metabolism, increase the soluble solids of the fruit and make the coloring more uniform.

[0023] 3. Environmental friendliness and soil improvement: The raw materials used in the preparation are biodegradable plant-based compounds, which are environmentally friendly; chelating agents can improve soil structure, increase organic matter, reduce fertilizer use, and reduce the risk of agricultural non-point source pollution.

[0024] 4. The nano-fruit tree trace element compound fertilizer prepared by the present invention can significantly reduce the fruit cracking rate of fruit trees, improve the regularity of fruit shape, and enhance the hardness of fruit, and has a good effect of increasing yield and improving quality of fruit trees. DETAILED DESCRIPTION

[0025] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention object, the following is a detailed description in conjunction with examples and comparative examples:

[0026] An experiment was conducted in an apple orchard. 140 apple trees with similar growth conditions were selected and divided into 7 groups, with 20 trees in each group. Conventional fertilization methods were used. During the flower bud differentiation period of the apple trees (15 days before budding), 8 kg of compound fertilizer was applied per mu by flushing, 800 times the solution was sprayed on the leaves per mu during the young fruit period (20 days after flowering), and 12 kg per mu was applied by drip irrigation during the expansion period (when the fruit diameter was 3 cm).

[0027] 1. Fruit cracking rate of fruit trees: Check whether there are obvious cracks on the surface of the fruit. Any fruit with cracks is determined to be cracked fruit; the reduction ratio of fruit cracking rate = (n1-n2) / n1*100%, where n1 is the number of cracked fruits without using compound fertilizers, and n2 is the number of cracked fruits with using compound fertilizers.

[0028] 2. Fruit regularity: The fruit with an aspect ratio of 0.9-1.1 is relatively regular; the improvement ratio of fruit regularity = (S2-S1) / S1*100%, where S1 is the average score of fruit regularity without using compound fertilizer, and S2 is the average score of fruit regularity with using compound fertilizer.

[0029] 3. Fruit hardness: Measured using a fruit hardness meter, the increase in fruit hardness = (h2-h1) / h1*100%, where h1 is the average hardness value without using compound fertilizer, and h2 is the average hardness value with using compound fertilizer.

[0030] Example 1

[0031] A trace element compound fertilizer for fruit trees based on nano-chelation technology is characterized by being prepared from the following raw materials: 5g of zinc compound, 3g of iron compound, 3g of manganese compound, 2g of boron compound, 1g of copper compound, 0.5g of molybdenum compound, and 10g of phytic acid chelating agent.

[0032] The zinc element compound is zinc sulfate; the iron element compound is ferrous sulfate; the manganese element compound is manganese sulfate; the boron element compound is borax; the copper element compound is copper sulfate; and the molybdenum element compound is sodium molybdate.

[0033] The preparation method of the nano-scale trace element compound fertilizer for fruit trees is as follows:

[0034] S1: Mix a zinc compound, an iron compound, a manganese compound, a boron compound, a copper compound, a molybdenum compound, and a phytic acid chelating agent, add the mixture to 120 g of water, and stir until a uniform solution is formed;

[0035] S2: Heat the mixed solution to 50°C, adjust the pH to 4, and stir the mixture for 2 hours.

[0036] S3: After the reaction is completed, the product is dried into powder by spray drying to obtain a nano-scale trace element compound fertilizer for fruit trees.

[0037] The preparation method of the phytic acid chelating agent is as follows:

[0038] A1: Add 10g of phytic acid to a reactor, add 130g of ethanol and stir to dissolve, heat to 50°C, add 0.1g of citric acid catalyst, and stir for 10 minutes to activate the system;

[0039] A2: Slowly add 5g of imidazolidinone malonic acid while stirring over 3 hours. After the addition is complete, maintain the temperature at 50°C and stir for 2 hours. Raise the temperature to 70°C and slowly add 20g of epoxy linseed oil. After the addition is complete, maintain the temperature at 70°C and stir for 3 hours.

[0040] A3: After the reaction is completed, the mixture is cooled to room temperature and ethanol, unreacted arginine and epoxy linseed oil are removed by distillation under reduced pressure to obtain a phytic acid chelating agent.

[0041] The nano-level trace element compound fertilizer for fruit trees is applied in fruit tree planting, and root topdressing is performed during the flower bud differentiation period, young fruit period and swelling period of the fruit trees, with the amount of root topdressing per mu being 5 kilograms.

[0042] Example 2

[0043] A trace element compound fertilizer for fruit trees based on nano-chelation technology is characterized by being prepared from the following raw materials: 6g of zinc compound, 4g of iron compound, 4g of manganese compound, 3g of boron compound, 2g of copper compound, 1g of molybdenum compound, and 13g of phytic acid chelating agent.

[0044] The zinc element compound is zinc sulfate; the iron element compound is ferrous sulfate; the manganese element compound is manganese sulfate; the boron element compound is borax; the copper element compound is copper sulfate; and the molybdenum element compound is sodium molybdate.

[0045] The preparation method of the nano-scale trace element compound fertilizer for fruit trees is as follows:

[0046] S1: Mix a zinc compound, an iron compound, a manganese compound, a boron compound, a copper compound, a molybdenum compound, and a phytic acid chelating agent, add the mixture to 140 g of water, and stir until a uniform solution is formed;

[0047] S2: Heat the mixed solution to 60°C, adjust the pH to 5, and stir the mixture for 3 hours.

[0048] S3: After the reaction is completed, the product is dried into powder by spray drying to obtain a nano-scale trace element compound fertilizer for fruit trees.

[0049] The preparation method of the phytic acid chelating agent is as follows:

[0050] A1: Add 13g of phytic acid to a reactor, add 140g of ethanol and stir to dissolve, heat to 55°C, add 0.5g of citric acid catalyst, and stir for 10 minutes to activate the system;

[0051] A2: Slowly add 8g of imidazolidinone malonic acid while stirring over 4 hours. After the addition is complete, maintain the temperature at 55°C and stir for 2.5 hours. Raise the temperature to 75°C and slowly add 25g of epoxy linseed oil. After the addition is complete, maintain the temperature at 75°C and stir for 4 hours.

[0052] A3: After the reaction is completed, the mixture is cooled to room temperature and ethanol, unreacted arginine and epoxy linseed oil are removed by distillation under reduced pressure to obtain a phytic acid chelating agent.

[0053] The nano-level trace element compound fertilizer for fruit trees is applied in fruit tree planting, and root topdressing is performed during the flower bud differentiation period, young fruit period and swelling period of the fruit trees, with the amount of root topdressing applied being 8 kilograms per mu.

[0054] Example 3

[0055] A trace element compound fertilizer for fruit trees based on nano-chelation technology is characterized by being prepared from the following raw materials: 8g of zinc compound, 7g of iron compound, 6g of manganese compound, 5g of boron compound, 3g of copper compound, 2g of molybdenum compound, and 18g of phytic acid chelating agent.

[0056] The zinc element compound is zinc oxide; the iron element compound is ferric citrate; the manganese element compound is manganese chloride; the boron element compound is boric acid; the copper element compound is copper oxide; and the molybdenum element compound is ammonium molybdate.

[0057] The preparation method of the nano-scale trace element compound fertilizer for fruit trees is as follows:

[0058] S1: Mix a zinc compound, an iron compound, a manganese compound, a boron compound, a copper compound, a molybdenum compound, and a phytic acid chelating agent, add the mixture to 160 g of water, and stir until a uniform solution is formed;

[0059] S2: Heat the mixed solution to 70°C, adjust the pH to 5, and stir the mixture for 3 hours.

[0060] S3: After the reaction is completed, the product is dried into powder by spray drying to obtain a nano-scale trace element compound fertilizer for fruit trees.

[0061] The preparation method of the phytic acid chelating agent is as follows:

[0062] A1: Add 18g of phytic acid to a reactor, add 150g of ethanol and stir to dissolve, heat to 55°C, add 0.8g of citric acid catalyst, and stir for 15 minutes to activate the system;

[0063] A2: Slowly add 13g of imidazolidinone malonic acid while stirring over 5 hours. After the addition is complete, maintain the temperature at 55°C and stir for 2.5 hours. Raise the temperature to 85°C and slowly add 35g of epoxy linseed oil. After the addition is complete, maintain the temperature at 85°C and stir for 4 hours.

[0064] A3: After the reaction is completed, the mixture is cooled to room temperature and ethanol, unreacted arginine and epoxy linseed oil are removed by distillation under reduced pressure to obtain a phytic acid chelating agent.

[0065] The nano-level trace element compound fertilizer for fruit trees is applied in fruit tree planting, and root topdressing is performed during the flower bud differentiation period, young fruit period and swelling period of the fruit trees, with the amount of root topdressing applied being 13 kilograms per mu.

[0066] Example 4

[0067] A trace element compound fertilizer for fruit trees based on nano-chelation technology is characterized by being prepared from the following raw materials: 10g of zinc compound, 8g of iron compound, 7g of manganese compound, 6g of boron compound, 4g of copper compound, 3g of molybdenum compound, and 20g of phytic acid chelating agent.

[0068] The zinc element compound is zinc oxide; the iron element compound is ferric citrate; the manganese element compound is manganese chloride; the boron element compound is boric acid; the copper element compound is copper oxide; and the molybdenum element compound is ammonium molybdate.

[0069] The preparation method of the nano-scale trace element compound fertilizer for fruit trees is as follows:

[0070] S1: Mix a zinc compound, an iron compound, a manganese compound, a boron compound, a copper compound, a molybdenum compound, and a phytic acid chelating agent, add the mixture to 180 g of water, and stir until a uniform solution is formed;

[0071] S2: Heat the mixed solution to 80°C, adjust the pH to 6, and stir the mixture for 4 hours.

[0072] S3: After the reaction is completed, the product is dried into powder by spray drying to obtain a nano-scale trace element compound fertilizer for fruit trees.

[0073] The preparation method of the phytic acid chelating agent is as follows:

[0074] A1: Add 20g of phytic acid to a reactor, add 160g of ethanol and stir to dissolve, heat to 60°C, add 1g of citric acid catalyst, and stir for 15 minutes to activate the system;

[0075] A2: Slowly add 15g of imidazolidinone malonic acid while stirring over 6 hours. After the addition is complete, maintain the temperature at 60°C and stir for 3 hours. Raise the temperature to 90°C and slowly add 40g of epoxy linseed oil. After the addition is complete, maintain the temperature at 90°C and stir for 5 hours.

[0076] A3: After the reaction is completed, the mixture is cooled to room temperature and ethanol, unreacted arginine and epoxy linseed oil are removed by distillation under reduced pressure to obtain a phytic acid chelating agent.

[0077] The nano-level trace element compound fertilizer for fruit trees is applied in fruit tree planting, and root topdressing is performed during the flower bud differentiation period, young fruit period and swelling period of the fruit trees, with the amount of root topdressing applied being 15 kilograms per mu.

[0078] Comparative Example 1

[0079] A trace element compound fertilizer for fruit trees is characterized by being prepared from the following raw materials: 5g of zinc element compound, 3g of iron element compound, 3g of manganese element compound, 2g of boron element compound, 1g of copper element compound, and 0.5g of molybdenum element compound.

[0080] The zinc element compound is zinc sulfate; the iron element compound is ferrous sulfate; the manganese element compound is manganese sulfate; the boron element compound is borax; the copper element compound is copper sulfate; and the molybdenum element compound is sodium molybdate.

[0081] The preparation method of the nano-scale trace element compound fertilizer for fruit trees is as follows:

[0082] S1: Mix a zinc compound, an iron compound, a manganese compound, a boron compound, a copper compound, and a molybdenum compound, add the mixture to 120 g of water, and stir until a uniform solution is formed;

[0083] S2: Heat the mixed solution to 50°C, adjust the pH to 4, and stir the mixture for 2 hours.

[0084] S3: After the reaction is completed, the product is dried into powder by spray drying to obtain a nano-scale trace element compound fertilizer for fruit trees.

[0085] The nano-level trace element compound fertilizer for fruit trees is applied in fruit tree planting, and root topdressing is performed during the flower bud differentiation period, young fruit period and swelling period of the fruit trees, with the amount of root topdressing per mu being 5 kilograms.

[0086] Comparative Example 2

[0087] A trace element compound fertilizer for fruit trees is characterized by being prepared from the following raw materials: 5g of a zinc compound, 3g of an iron compound, 3g of a manganese compound, 2g of a boron compound, 1g of a copper compound, 0.5g of a molybdenum compound, and 10g of a phytic acid chelating agent.

[0088] The zinc element compound is zinc sulfate; the iron element compound is ferrous sulfate; the manganese element compound is manganese sulfate; the boron element compound is borax; the copper element compound is copper sulfate; and the molybdenum element compound is sodium molybdate.

[0089] The preparation method of the nano-scale trace element compound fertilizer for fruit trees is as follows:

[0090] S1: Mix a zinc compound, an iron compound, a manganese compound, a boron compound, a copper compound, a molybdenum compound, and a phytic acid chelating agent, add the mixture to 120 g of water, and stir until a uniform solution is formed;

[0091] S2: Heat the mixed solution to 50°C, adjust the pH to 4, and stir the mixture for 2 hours.

[0092] S3: After the reaction is completed, the product is dried into powder by spray drying to obtain a nano-scale trace element compound fertilizer for fruit trees.

[0093] The preparation method of the phytic acid chelating agent is as follows:

[0094] A1: Add 10g of phytic acid to a reactor, add 130g of ethanol and stir to dissolve, heat to 50°C, add 0.1g of citric acid catalyst, and stir for 10 minutes to activate the system;

[0095] A2: Raise the temperature to 70°C and slowly add 20g of epoxy linseed oil. After the addition is complete, maintain the temperature at 70°C and stir for 3 hours.

[0096] A3: After the reaction is completed, the mixture is cooled to room temperature and distilled under reduced pressure to obtain a phytic acid chelating agent.

[0097] The nano-level trace element compound fertilizer for fruit trees is applied in fruit tree planting, and root topdressing is performed during the flower bud differentiation period, young fruit period and swelling period of the fruit trees, with the amount of root topdressing per mu being 5 kilograms.

[0098] Comparative Example 3

[0099] A trace element compound fertilizer for fruit trees is characterized by being prepared from the following raw materials: 5g of a zinc compound, 3g of an iron compound, 3g of a manganese compound, 2g of a boron compound, 1g of a copper compound, 0.5g of a molybdenum compound, and 10g of a phytic acid chelating agent.

[0100] The zinc element compound is zinc sulfate; the iron element compound is ferrous sulfate; the manganese element compound is manganese sulfate; the boron element compound is borax; the copper element compound is copper sulfate; and the molybdenum element compound is sodium molybdate.

[0101] The preparation method of the nano-scale trace element compound fertilizer for fruit trees is as follows:

[0102] S1: Mix a zinc compound, an iron compound, a manganese compound, a boron compound, a copper compound, a molybdenum compound, and a phytic acid chelating agent, add the mixture to 120 g of water, and stir until a uniform solution is formed;

[0103] S2: Heat the mixed solution to 50°C, adjust the pH to 4, and stir the mixture for 2 hours.

[0104] S3: After the reaction is completed, the product is dried into powder by spray drying to obtain a nano-scale trace element compound fertilizer for fruit trees.

[0105] The preparation method of the phytic acid chelating agent is as follows:

[0106] A1: Add 10g of phytic acid to a reactor, add 130g of ethanol and stir to dissolve, heat to 50°C, add 0.1g of citric acid catalyst, and stir for 10 minutes to activate the system;

[0107] A2: Slowly add 5g of imidazolidinone malonic acid while stirring. Control the addition time to 3 hours. After the addition is complete, maintain the temperature at 50°C and stir for 2 hours.

[0108] A3: After the reaction is completed, the mixture is cooled to room temperature and distilled under reduced pressure to obtain a phytic acid chelating agent.

[0109] The nano-level trace element compound fertilizer for fruit trees is applied in fruit tree planting, and root topdressing is performed during the flower bud differentiation period, young fruit period and swelling period of the fruit trees, with the amount of root topdressing per mu being 5 kilograms.

[0110] Table 1: Experimental data of Examples and Comparative Examples

[0111] Fruit cracking rate reduction ratio / % Weekly regularity improvement ratio / % Hardness increase / % Example 1 36 34 23 Example 2 38 35 24 Example 3 41 37 26 Example 4 43 38 27 Comparative Example 1 22 18 10 Comparative Example 2 28 27 18 Comparative Example 3 30 29 19

[0112] Through data analysis of the embodiments and comparative examples, the nano-fruit tree trace element compound fertilizer prepared by the present invention can significantly reduce the fruit cracking rate of fruit trees, improve the regularity of fruit shape, and enhance the hardness of fruit, and has a good effect of increasing yield and improving quality of fruit trees.

[0113] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A trace element compound fertilizer for fruit trees based on nano-chelation technology, characterized by: The invention is prepared from the following raw materials in parts by weight: 5-10 parts of a zinc compound, 3-8 parts of an iron compound, 3-7 parts of a manganese compound, 2-6 parts of a boron compound, 1-4 parts of a copper compound, 0.5-3 parts of a molybdenum compound, and 10-20 parts of a phytic acid chelating agent. The phytic acid chelating agent is prepared from phytic acid, ethanol, citric acid, imidazolidinone malonic acid and epoxy linseed oil.

2. The trace element compound fertilizer for fruit trees based on nano-chelation technology according to claim 1, characterized in that: The zinc compound is zinc sulfate or zinc oxide; the iron compound is ferrous sulfate or ferric citrate; the manganese compound is manganese sulfate or manganese chloride; the boron compound is borax or boric acid; the copper compound is copper sulfate or copper oxide; and the molybdenum compound is sodium molybdate or ammonium molybdate.

3. The trace element compound fertilizer for fruit trees based on nano-chelation technology according to claim 1, characterized in that: The preparation method of the trace element compound fertilizer for fruit trees is as follows: S1: Mix a zinc compound, an iron compound, a manganese compound, a boron compound, a copper compound, a molybdenum compound, and a phytic acid chelating agent in parts by weight, add the mixture to 120-180 parts of water, and stir until a uniform solution is formed; S2: Heat the mixed solution to 50-80°C, adjust the pH to 4-6, and stir the mixture for 2-4 hours; S3: After the reaction is completed, the product is dried into powder by spray drying to obtain a nano-scale trace element compound fertilizer for fruit trees.

4. The trace element compound fertilizer for fruit trees based on nano-chelation technology according to claim 1, characterized in that: The preparation method of the phytic acid chelating agent is as follows: A1: Add 10-20 parts of phytic acid to a reactor, add 130-160 parts of ethanol and stir to dissolve, heat to 50-60°C, add 0.1-1 parts of citric acid catalyst, and stir for 10-15 minutes to activate the system; A2: Slowly add 5-15 parts of imidazolidinonemalonic acid while stirring, controlling the addition time to 3-6 hours. After the addition is complete, maintain the temperature at 50-60°C and stir for 2-3 hours. Raise the temperature to 70-90°C and slowly add 20-40 parts of epoxy linseed oil. After the addition is complete, maintain the temperature at 70-90°C and stir for 3-5 hours. A3: After the reaction is completed, the mixture is cooled to room temperature and ethanol, unreacted arginine and epoxy linseed oil are removed by distillation under reduced pressure to obtain a phytic acid chelating agent.

5. An application of a trace element compound fertilizer for fruit trees based on nano-chelation technology, characterized by: The trace element compound fertilizer for fruit trees according to claim 1 is applied to fruit tree planting, and root topdressing is performed during the flower bud differentiation period, young fruit period and swelling period of the fruit trees, with the amount of root topdressing per mu being 5-15 kg.