Macronutrient water-soluble fertilizer and preparation method thereof

Abstract

The present application relates to a kind of macroelement water-soluble fertilizer and its preparation method, belong to water-soluble fertilizer field, according to percentage by weight, including urea 25~30%, potassium nitrate 30.0~35.0%, polyphosphate 15~20%, compound chelated state trace metal element 18~20%, potassium phosphite 1.0~2.0%, sodium octaborate 0.1~0.3%;The compound chelated state trace metal element includes calcium nitrate tetrahydrate, magnesium sulfate heptahydrate, ferrous sulfate heptahydrate, zinc sulfate heptahydrate, citric acid monohydrate, tartaric acid, poly-p-glutamic acid, glycine, potassium fulvic acid, mulberry bark extract and radix scrophulariae extract.The trace metal element of the present application is treated by step chelation, and the content of initial chelated state trace element is significantly higher than all the comparative examples, and the macroelement water-soluble fertilizer of the present application can effectively improve crop yield, and reduce the stress resistance of crop.

Description

Technical Field

[0001] This invention relates to a water-soluble fertilizer containing macro-elements and its preparation method, belonging to the field of water-soluble fertilizers. Background Technology

[0002] As a novel type of fertilizer, water-soluble fertilizer containing macronutrients offers numerous advantages unmatched by traditional fertilizers. It dissolves rapidly in water, forming a uniform fertilizer solution that can be directly delivered to the roots of crops via drip irrigation or sprinkler irrigation, achieving integrated water and fertilizer management. This significantly improves fertilizer absorption and utilization rates, reducing nutrient loss and waste. Furthermore, water-soluble fertilizers can be precisely formulated to meet the nutritional needs of different crops at different growth stages, providing a comprehensive and balanced nutrient supply, effectively promoting crop growth and development, and increasing yield and quality. Simultaneously, its ease of use and high efficiency save labor costs, aligning with the trend of modern agriculture towards large-scale and intensive development.

[0003] In the formulation design and production of water-soluble fertilizers, especially high-concentration, all-nutrient water-soluble fertilizers, a long-standing and unresolved technical bottleneck is how to achieve the long-term stable coexistence of multiple micronutrients in the fertilizer solution and ensure their efficient absorption and utilization by crops, ultimately achieving a balanced supply of nutrients and synergistic enhancement of functions.

[0004] To improve the availability and stability of trace elements and prevent them from precipitating in fertilizer solutions or being fixed in soil, existing technologies generally employ chelation techniques, which can be mainly divided into the following types: (1) Using synthetic chelating agents (such as EDTA): Directly adding ethylenediaminetetraacetic acid (EDTA) to chelate iron, copper, zinc, manganese, boron, etc., to form stable chelates presents problems: Synthetic chelating agents such as EDTA are difficult to degrade in the environment, and long-term use may lead to the activation and migration of heavy metals in the soil, posing a risk of environmental accumulation. When multiple EDTA-chelated metals coexist in high-concentration fertilizer solutions, the chelation stability constants of different metal ions with EDTA vary greatly, with strong chelating ions (such as Fe) showing the greatest difference. 3+ It may be from weakly chelated ions (such as Ca) 2+ Zn 2+ The ions snatch away EDTA ligands from the fertilizer solution, causing weak chelating ions to be released. These ions then react with phosphate, sulfate, hydroxide, and other ions in the fertilizer solution to form precipitates (such as calcium phosphate and zinc hydroxide). This intensifies the chemical antagonism between elements, resulting in nutrient loss and deterioration of the product's physical properties.

[0005] (2) Use organic acids or simple organic ligands: Use citric acid, amino acids, etc. as chelating agents and acidifiers; the chelation stability constants of citric acid, amino acids, etc. for most trace elements are much lower than those of EDTA. Under conditions of long-term storage of fertilizer solution, extreme pH or high concentration of electrolytes, the chelate is easy to dissociate and cannot effectively prevent the precipitation reaction of metal ions with anions such as phosphorus and sulfur, making it difficult to ensure the long-term stability of high-concentration complete nutrient formula.

[0006] Therefore, it is of great significance to develop a water-soluble fertilizer that can improve the chelation stability of micronutrients in macronutrient water-soluble fertilizers, reduce the antagonistic effects between elements, ensure a balanced supply of various nutrients in fertilizers, and enhance the stress resistance and quality of crops. Summary of the Invention

[0007] This invention provides a water-soluble fertilizer containing macro-elements and its preparation method, which solves the problems of existing chelation technology, such as the inability to systematically address multi-element antagonism, insufficient stability, and limited functional dimensions.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A water-soluble fertilizer containing macro-elements, by weight percentage, comprises 25-30% urea, 30.0-35.0% potassium nitrate, 15-20% ammonium polyphosphate, 18-20% complex chelated trace metal elements, 1.0-2.0% potassium phosphite, and 0.1-0.3% sodium octaborate tetrahydrate. The complex chelated trace metal elements, by weight, comprise 8.0-12.0 parts calcium nitrate tetrahydrate, 6.0-9.0 parts magnesium sulfate heptahydrate, 5.0-7.0 parts ferrous sulfate heptahydrate, 2.0-3.0 parts zinc sulfate heptahydrate, 10.0-12.0 parts citric acid monohydrate, 5.0-8.0 parts tartaric acid, 5-8 parts polyglutamic acid, 4.0-6.0 parts glycine, 20.0-25.0 parts potassium humate, 1.5-2.5 parts mulberry bark extract, and 1.5-2.5 parts scutellaria baicalensis extract.

[0009] Preferably, the mulberry bark extract has a ratio of 10:1.

[0010] Preferably, the baicalin content in the scutellaria extract is above 80%.

[0011] Preferably, the method for preparing trace metal elements in the composite chelate state includes the following steps: (1) Add 30-50% of the total weight of trace metal elements in deionized water while stirring at 150-200 rpm, then add citric acid and tartaric acid, stir until completely dissolved, heat to 45±2℃, add calcium nitrate and magnesium sulfate in sequence, continue stirring, adjust the pH of the system to 4.0-4.5, react for 20-30 min to form a stable calcium and magnesium small molecule acid complex; (2) Keep the temperature at 45±2℃. Dissolve polyglutamic acid and glycine in a small amount of warm water beforehand, and add them to the solution in step (1). Stir at 300-400 rpm. Then dissolve ferrous sulfate and zinc sulfate in a small amount of water and slowly add them to the reaction system in batches. After the addition is complete, slowly adjust the pH of the system to 5.5-6.0 with dilute alkali solution and stir at a constant temperature for 40-50 min. (3) Slowly adjust the pH of the system to 7.5-8 with dilute alkali solution, mix the mulberry bark extract and scutellaria extract, dissolve in warm water, lower the reaction temperature to 40±2℃, add the mixed extract to the reaction system, and stir at 150-200 rpm for 20-25 min. (4) Slowly adjust the pH of the system to 5.5-6 with dilute acid solution, stir potassium humate with an appropriate amount of warm water to form a uniform slurry, add it to the solution in step (3), stir at a speed of 500-600 rpm, and continue to react for 30 min at 40±2℃. (5) Spray dry the obtained viscous slurry, set the inlet temperature to 130-140℃ and the outlet temperature to 85-90℃, quickly dry and shape it, collect the dried powder, and pass it through an 80-100 mesh sieve to obtain trace metal elements in the composite chelated state.

[0012] The method for preparing the water-soluble fertilizer containing macro-elements of the present invention includes the following steps: (1) At a speed of 200-300 rpm and a temperature of 55-60℃, add water of 30-40% of the total weight of the raw materials, and then add urea, potassium nitrate, ammonium polyphosphate, potassium phosphite and sodium octaborate tetrahydrate in sequence. Stir and heat until completely dissolved to obtain the basic mother liquor. (2) Cool the base mother liquor to below 40°C, add the viscous slurry-like composite chelated trace metal elements, and stir until completely dispersed and uniform; (3) Spray granulation of the stirred slurry, and after sieving, obtain finished particles with a particle size of 1-4 mm. After the finished product passes the inspection, seal and moisture-proof packaging.

[0013] The beneficial effects of this invention are:

[0014] This invention utilizes a stepwise, graded chelation process to fundamentally avoid the precipitation problems caused by competition for ligands or reactions with anions in high-concentration solutions for elements such as calcium (Ca), magnesium (Mg), iron (Fe), and zinc (Zn), ensuring the highly stable coexistence of multiple nutrients. The addition of mulberry bark extract and polyglutamic acid, two potent ligands, further enhances the precipitation of elements such as calcium (Ca), magnesium (Mg), iron (Fe), and zinc (Zn) in high-concentration solutions. 3+ / Fe 2+The strong chelating ability of transition metal ions ensures high overall chelation stability of the final complex, guaranteeing the long-term effectiveness and high utilization rate of nutrients in the soil. This invention deeply integrates mulberry bark extract and scutellaria baicalensis extract into the chelated structure, not only endowing the product with biological functions that enhance crop stress resistance (resistance to drought, disease, etc.) and promote growth, but also achieving molecular-level binding between functional components and nutrient carriers, preventing the loss of functional components.

[0015] The preparation method of this invention achieves synergistic effects of multiple components through hierarchical chelation and functionalization encapsulation: First, under acidic conditions of pH 4.0-4.5, citric acid and tartaric acid preferentially react with Ca... 2+ Mg 2+ Complexation occurs, forming soluble complexes that effectively prevent early precipitation of calcium phosphate and other substances, establishing initial stability for the system. Then, in a near-neutral environment of pH 5.5-6.0, polyglutamic acid and glycine, through their abundant amino and carboxyl groups, react with Fe... 2+ Zn 2+ A stable chelate is formed, providing a structural basis for the subsequent integration of plant polyphenols. The two complement each other in coordination and spatial configuration, enhancing chelation capacity and stability. Then, under weakly alkaline conditions of pH 7.5-8.0, the phenolic hydroxyl groups in mulberry bark extract (containing catechol structure) and scutellaria baicalensis extract dissociate into phenolic anions, forming a stronger and more inert coordination structure with Fe ions, significantly improving overall thermodynamic stability. Furthermore, their antioxidant and stress-resistance bioactivities are embedded in the nutrient carrier, achieving molecular-level fusion and synergistic release of nutrition and stress-resistance functions. Finally, the pH of the system is adjusted to 5.5-6.0, and potassium humate is added. Its macromolecular network structure physically encapsulates the aforementioned chelate core, providing steric hindrance, completely preventing secondary antagonism during use, slowing nutrient dissociation in the soil, and achieving slow release. Simultaneously, potassium humate, as a biostimulant, further promotes root development, synergistically enhancing the overall biological effect with the active ingredients of the inner plant layers.

[0016] The trace metal elements of this invention undergo stepwise chelation treatment, and the initial chelated trace element content (865.9 mg / kg) is significantly higher than that of all comparative examples. After 6 months of storage, Example 1 still maintains 847.4 mg / kg, a decrease of only 2.1%. The large-capacity element water-soluble fertilizer of this invention can effectively increase crop yield and reduce stress resistance. Detailed Implementation

[0017] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative effort are also described. Example 1

[0018] A water-soluble fertilizer containing macro-elements, by weight percentage, comprises 28% urea, 34% potassium nitrate, 18% ammonium polyphosphate, 18% complex chelated trace metal elements, 1.8% potassium phosphite, and 0.2% sodium octaborate tetrahydrate. The complex chelated trace metal elements, by weight, comprise 10.0 parts calcium nitrate tetrahydrate, 8.0 parts magnesium sulfate heptahydrate, 5.0 parts ferrous sulfate heptahydrate, 3.0 parts zinc sulfate heptahydrate, 12.0 parts citric acid monohydrate, 7.0 parts tartaric acid, 6 parts polyglutamic acid, 5 parts glycine, 25.0 parts potassium humate, 2 parts mulberry bark extract, and 2.5 parts scutellaria baicalensis extract. The mulberry bark extract has a ratio of 10:1, and the scutellaria baicalensis extract contains over 80% baicalin.

[0019] A method for preparing trace metal elements in a complex chelated state includes the following steps: (1) Add 30% of the total weight of trace metal elements in deionized water while stirring at 200 rpm, then add citric acid and tartaric acid, stir until completely dissolved, heat to 45±2℃, add calcium nitrate and magnesium sulfate in sequence, continue stirring, adjust the pH of the system to 4.0-4.5, react for 30 min, and form a stable calcium and magnesium small molecule acid complex. (2) Keep the temperature at 45±2℃. Dissolve polyglutamic acid and glycine in a small amount of warm water beforehand, and add them to the solution in step (1). Stir at 300 rpm, then dissolve ferrous sulfate and zinc sulfate in a small amount of water and slowly add them to the reaction system in batches. After the addition is complete, slowly adjust the pH of the system to 5.5-6.0 with dilute alkali solution and stir at a constant temperature for 40 min. (3) Slowly adjust the pH of the system to 7.5-8 with dilute alkali solution, mix the mulberry bark extract and scutellaria extract, dissolve in warm water, lower the reaction temperature to 40±2℃, add the mixed extract to the reaction system, and stir at 200 rpm for 25 min. (4) Slowly adjust the pH of the system to 5.5-6 with dilute acid solution, stir potassium humate with an appropriate amount of warm water to form a uniform slurry, add it to the solution in step (3), stir at 600 rpm, and continue to react for 30 min at 40±2℃. (5) Spray dry the obtained viscous slurry, set the inlet temperature to 130-140℃ and the outlet temperature to 85-90℃, quickly dry and shape it, collect the dried powder, and pass it through an 80-100 mesh sieve to obtain trace metal elements in the composite chelated state.

[0020] The preparation method of water-soluble fertilizer containing macro-elements includes the following steps: (1) At a speed of 300 rpm and a temperature of 57±2℃, add water at a weight of 30% of the total weight of the raw materials, and then add urea, potassium nitrate, ammonium polyphosphate, potassium phosphite, and sodium octaborate tetrahydrate in sequence. Stir and heat until completely dissolved to obtain the basic mother liquor. (2) Cool the base mother liquor to below 40°C, add the viscous slurry-like composite chelated trace metal elements, and stir until completely dispersed and uniform; (3) Spray granulation of the stirred slurry, and after sieving, obtain finished particles with a particle size of 1-4 mm. After the finished product passes the inspection, seal and moisture-proof packaging.

[0021] Comparative Example 1

[0022] The method is basically the same as in Example 1, except that the trace metal elements in the composite chelate state, by weight, include 10.0 parts of calcium nitrate tetrahydrate, 8.0 parts of magnesium sulfate heptahydrate, 5.0 parts of ferrous sulfate heptahydrate, 3.0 parts of zinc sulfate heptahydrate, 19 parts of EDTA, 6 parts of polyglutamic acid, 5 parts of glycine, 25.0 parts of potassium humate, 2 parts of mulberry bark extract, and 2.5 parts of scutellaria baicalensis extract.

[0023] Its preparation method is as follows: (1) Add 19.0 parts of EDTA to 60 parts of deionized water and stir until completely dissolved. While stirring at 200 rpm, slowly add 30% sodium hydroxide solution to adjust the pH of the system to 8.5 to obtain a sodium EDTA solution. (2) Dissolve 10.0 parts of calcium nitrate tetrahydrate in 10 parts of deionized water to obtain a calcium salt solution; dissolve 8.0 parts of magnesium sulfate heptahydrate in 10 parts of deionized water to obtain a magnesium salt solution; dissolve 5.0 parts of ferrous sulfate heptahydrate in 5 parts of deionized water to obtain a ferrous salt solution; dissolve 3.0 parts of zinc sulfate heptahydrate in 5 parts of deionized water to obtain a zinc salt solution; (3) Raise the temperature to 45±2℃, rotate at 200 rpm, and slowly add calcium salt solution and magnesium salt solution to DETA sodium salt solution. Control the dropping rate to maintain the pH of the reaction system at 6.0 (adjusted by adding sodium hydroxide solution simultaneously). After the addition is complete, continue stirring for 10 minutes. Then slowly add zinc salt solution, again controlling the pH at 6.0. After the addition is complete, stir for 10 minutes. Slowly add ferrous salt solution, controlling the pH at 6.0. (4) After all the metal salts have been added, continue stirring the reaction at 50°C for 30 minutes to ensure complete chelation; spray dry the obtained chelate solution, set the inlet temperature to 150-160°C and the outlet temperature to 80-90°C, collect the dried powder, pass it through an 80-100 mesh sieve, and then mix it evenly with 6 parts of polyglutamic acid, 5 parts of glycine, 25.0 parts of potassium humate, 2 parts of mulberry bark extract, and 2.5 parts of scutellaria baicalensis extract to obtain the trace metal elements in the composite chelate state.

[0024] Comparative Example 2

[0025] The process is basically the same as in Example 1, except that polyglutamic acid, glycine, mulberry bark extract, and scutellaria baicalensis extract do not participate in chelation but are added as nutrients to the trace metal elements in the complex chelated state. Steps (2) and (3) are omitted. Ferrous sulfate and zinc sulfate are dissolved in a small amount of water and then slowly and in batches added to the product after the reaction in step (1). The specific steps are as follows: A method for preparing trace metal elements in a complex chelated state includes the following steps: (1) Add 30% of the total weight of trace metal elements in deionized water while stirring at 200 rpm, then add citric acid and tartaric acid, stir until completely dissolved, heat to 45±2℃, add calcium nitrate and magnesium sulfate in sequence, continue stirring, adjust the pH of the system to 4.0-4.5, react for 30 min, and form a stable calcium and magnesium small molecule acid complex. (2) Then, ferrous sulfate and zinc sulfate are dissolved in a small amount of water and slowly added to the reaction system in batches. After the addition is complete, the pH of the system is slowly adjusted to 5.5-6.0 with dilute alkali solution and the reaction is stirred at a constant temperature for 40 minutes. (3) Stir potassium humate with an appropriate amount of warm water to form a uniform slurry, add it to the solution in step (2), stir at 600 rpm, and continue to react for 30 min at 40±2℃. (4) Spray dry the obtained viscous slurry, set the inlet temperature to 130-140℃ and the outlet temperature to 85-90℃, dry and shape quickly, collect the dried powder, pass it through an 80-100 mesh sieve, and then mix it evenly with polyglutamic acid, glycine, mulberry bark extract and scutellaria extract to obtain a composite chelated state of trace metal elements.

[0026] Comparative Example 3

[0027] The process is basically the same as in Example 1, except that polyglutamic acid and glycine do not participate in chelation but are added as nutrients to the trace metal elements in the complex chelated state. Step (2) is omitted. The specific steps are as follows: A method for preparing trace metal elements in a complex chelated state includes the following steps: (1) Add 30% of the total weight of trace metal elements in deionized water while stirring at 200 rpm, then add citric acid and tartaric acid, stir until completely dissolved, heat to 45±2℃, add calcium nitrate and magnesium sulfate in sequence, continue stirring, adjust the pH of the system to 4.0-4.5, react for 30 min, and form a stable calcium and magnesium small molecule acid complex. (2) Keep the temperature at 45±2℃ and stir at 300rpm. Then dissolve ferrous sulfate and zinc sulfate in a small amount of water and slowly add them to the reaction system in batches. After the addition is complete, slowly adjust the pH of the system to 5.5-6.0 with dilute alkali solution and stir at a constant temperature for 40min. (3) Slowly adjust the pH of the system to 7.5-8 with dilute alkali solution, mix the mulberry bark extract and scutellaria extract, dissolve in warm water, lower the reaction temperature to 40±2℃, add the mixed extract to the reaction system, and stir at 200 rpm for 25 min. (4) Slowly adjust the pH of the system to 5.5-6 with dilute acid solution, stir potassium humate with an appropriate amount of warm water to form a uniform slurry, add it to the solution in step (3), stir at 600 rpm, and continue to react for 30 min at 40±2℃. (5) Spray dry the obtained viscous slurry, set the inlet temperature to 130-140℃ and the outlet temperature to 85-90℃, dry and shape quickly, collect the dried powder, pass it through an 80-100 mesh sieve, and then mix it evenly with polyglutamic acid and glycine to obtain trace metal elements in the composite chelated state.

[0028] Comparative Example 4

[0029] The process is basically the same as in Example 1, except that the mulberry bark extract and scutellaria extract do not participate in chelation and are added as nutrients to the trace metal elements in the composite chelated state. Step (3) is omitted.

[0030] Comparative Example 5

[0031] The process is basically the same as in Example 1, except that potassium humate does not participate in chelation and is added as a nutrient to the trace metal elements in the composite chelated state. Step (4) is omitted.

[0032] Effect measurement:

[0033] Chelation stability test

[0034] Referring to the testing standard HG / T5331-2018 "Compound Fertilizers Containing Chelated Trace Elements (Compound Fertilizers)", an inductively coupled plasma atomic emission spectrometer was used; then, the prepared water-soluble fertilizer containing macroelements was stored at room temperature and protected from light, and the chelated trace elements were measured at 0, 3 and 6 months.

[0035]

[0036] Note: Different lowercase letters after the data in the same column indicate significant differences (P<0.05).

[0037] As shown in Table 1, the trace metal elements of this invention, after stepwise chelation treatment, had an initial chelated trace element content (865.9 mg / kg) that was significantly higher than all comparative examples, and 52.4% higher than that of Comparative Example 2. After 6 months of storage, Example 1 still maintained 847.4 mg / kg, decreasing by only 2.1%; while Comparative Example 1 decreased by 8.3% and Comparative Example 2 decreased by 29.9%. At all time points, the chelated trace element content of Example 1 was significantly different from other groups (P<0.05), showing a clear statistical advantage.

[0038] Fertilizer Efficacy Experiment:

[0039] In accordance with the provisions of NY / T 497—2002 "Technical Regulations for Field Trials to Identify Fertilizer Effects", an experiment was conducted at an experimental base in Shandong Province to grow tomatoes in greenhouses. The yield of the tomatoes was measured.

[0040] The soil used in the experiment was neutral to slightly acidic brown soil, with available nitrogen of 83.65 mg / kg, available phosphorus of 24.23 mg / kg, pH of 6.5, organic matter of 13.63 mg / kg, and available potassium of 136.58 mg / kg. The previous crop was Chinese cabbage. The tested variety was TF423.

[0041] The experiment included seven treatments, each repeated three times, arranged randomly. Each experimental plot measured 2.8 m × 10 m, or 28 m². 2 The planting spacing is 0.5 m × 0.6 m, and the planting density is 2,000 plants / 667 m². 2 .

[0042] One treatment served as a blank control, without the use of water-soluble fertilizers containing macro-elements. During the growth process, water was sprayed onto the leaves of tomatoes three times: at the 3-leaf stage, the budding stage, and the mid-harvest stage.

[0043] The remaining six treatments used the water-soluble fertilizers containing macroelements prepared in Example 1 and Comparative Examples 1-5, respectively. The experiments were conducted on the basis of conventional fertilization, with 200 kg / 667 m² applied during land preparation. 2 Organic fertilizer is used as base fertilizer. 20g of water-soluble fertilizer containing macro-elements is applied to each plant. During the growth process, a 500-fold dilution of water-soluble fertilizer containing micro-elements is sprayed on the leaves of tomatoes three times: at the 3-leaf stage, the budding stage, and the mid-harvest stage.

[0044] For each experimental field, the quality of the harvested fruit should be weighed and measured. During the experiment, random sampling was used, and 15 tomato plants were randomly selected from each experimental field. At each harvest, the weight of a single fruit was measured using an electronic balance, and the condition of diseased fruit was recorded in detail.

[0045] The disease rate is calculated using the following formula: Disease rate / % = Number of diseased fruits investigated / Total number of fruits investigated × 100.

[0046]

[0047] Note: Different lowercase letters after the data in the same column indicate significant differences (P<0.05).

[0048] As shown in Table 2, the yield of Example 1 was 3463.1 kg / 667m³. 2 The yield increase was 36.7% higher than the control group, 15.4% higher than control group 1, and 23.2% higher than control group 2, making it the highest among all formulations. The disease rate in Example 1 was only 2.1%, a decrease of 84.1% (13.2%→2.1%) compared to the control group and a decrease of 66.7% (6.3%→2.1%) compared to control group 1. The significance level (a) was extremely significant compared to all other groups (P<0.05).

[0049] As can be seen from Comparative Examples 2 and 4, this invention achieves the dual effects of high-stability chelation and strong stress resistance protection by adding mulberry bark extract and scutellaria baicalensis extract: on the one hand, the plant-derived active ingredients, as auxiliary chelating agents, significantly improve the chelation efficiency and storage stability of trace elements; on the other hand, the pharmacological activity of the two Chinese herbal extracts endows the fertilizer with dual-effect characteristics of both fertilizer and pesticide, greatly reducing the rate of crop disease and enhancing the crop's stress resistance, ultimately achieving a dual improvement in yield and quality. Example 2

[0050] A water-soluble fertilizer containing macro-elements, by weight percentage, comprises 30% urea, 33.7% potassium nitrate, 15% ammonium polyphosphate, 20% complex chelated trace metal elements, 1% potassium phosphite, and 0.3% sodium octaborate tetrahydrate. The complex chelated trace metal elements, by weight, comprise 8.0 parts calcium nitrate tetrahydrate, 7.0 parts magnesium sulfate heptahydrate, 6.0 parts ferrous sulfate heptahydrate, 2.0 parts zinc sulfate heptahydrate, 10.0 parts citric acid monohydrate, 5.0 parts tartaric acid, 6 parts polyglutamic acid, 4 parts glycine, 20.0 parts potassium humate, 1.5 parts mulberry bark extract, and 2 parts scutellaria baicalensis extract. The mulberry bark extract has a ratio of 10:1, and the scutellaria baicalensis extract contains over 80% baicalin. The preparation method is similar to the examples provided, but with different detailed descriptions. Example 3

[0051] A water-soluble fertilizer containing macro-elements, by weight percentage, comprises 25% urea, 35% potassium nitrate, 20% ammonium polyphosphate, 17.9% complex chelated trace metal elements, 2% potassium phosphite, and 0.1% sodium octaborate tetrahydrate. The complex chelated trace metal elements, by weight, comprise 12.0 parts calcium nitrate tetrahydrate, 9.0 parts magnesium sulfate heptahydrate, 7.0 parts ferrous sulfate heptahydrate, 2.5 parts zinc sulfate heptahydrate, 11.0 parts citric acid monohydrate, 6.0 parts tartaric acid, 7 parts polyglutamic acid, 5 parts glycine, 23.0 parts potassium humate, 2.5 parts mulberry bark extract, and 1.5 parts scutellaria baicalensis extract. The mulberry bark extract has a ratio of 10:1, and the scutellaria baicalensis extract contains over 80% baicalin. The preparation method is similar to the examples provided, but with different detailed descriptions. Example 4

[0052] A water-soluble fertilizer containing macro-elements, by weight percentage, comprises 30% urea, 30% potassium nitrate, 20% ammonium polyphosphate, 17.7% complex chelated trace metal elements, 2% potassium phosphite, and 0.3% sodium octaborate tetrahydrate. The complex chelated trace metal elements, by weight, comprise 10.0 parts calcium nitrate tetrahydrate, 6.0 parts magnesium sulfate heptahydrate, 5.0 parts ferrous sulfate heptahydrate, 3.0 parts zinc sulfate heptahydrate, 12.0 parts citric acid monohydrate, 8.0 parts tartaric acid, 5.0 parts polyglutamic acid, 6 parts glycine, 22.0 parts potassium humate, 2 parts mulberry bark extract, and 2 parts scutellaria baicalensis extract. The mulberry bark extract has a ratio of 10:1, and the scutellaria baicalensis extract contains over 80% baicalin. The preparation method is similar to the examples provided, but with different detailed descriptions.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A water-soluble fertilizer containing macro-elements, characterized in that: The composition, by weight percentage, includes 25-30% urea, 30.0-35.0% potassium nitrate, 15-20% ammonium polyphosphate, 18-20% complex chelated trace metal elements, 1.0-2.0% potassium phosphite, and 0.1-0.3% sodium octaborate tetrahydrate. The complex chelated trace metal elements, by weight, include 8.0-12.0 parts calcium nitrate tetrahydrate, 6.0-9.0 parts magnesium sulfate heptahydrate, 5.0-7.0 parts ferrous sulfate heptahydrate, 2.0-3.0 parts zinc sulfate heptahydrate, 10.0-12.0 parts citric acid monohydrate, 5.0-8.0 parts tartaric acid, 5-8 parts polyglutamic acid, 4.0-6.0 parts glycine, 20.0-25.0 parts potassium humate, 1.5-2.5 parts mulberry bark extract, and 1.5-2.5 parts scutellaria baicalensis extract.

2. The water-soluble fertilizer containing macro-elements according to claim 1, characterized in that: The specification of the mulberry bark extract is 10:

1.

3. The water-soluble fertilizer containing macro-elements according to claim 1, characterized in that: The Scutellaria baicalensis extract contains more than 80% baicalin.

4. The water-soluble fertilizer containing macro-elements according to claim 1, characterized in that: The method for preparing trace metal elements in the composite chelate state includes the following steps: (1) Add 30-50% of the total weight of trace metal elements in deionized water while stirring at 150-200 rpm, then add citric acid and tartaric acid, stir until completely dissolved, heat to 45±2℃, add calcium nitrate and magnesium sulfate in sequence, continue stirring, adjust the pH of the system to 4.0-4.5, react for 20-30 min to form a stable calcium and magnesium small molecule acid complex; (2) Keep the temperature at 45±2℃. Dissolve polyglutamic acid and glycine in a small amount of warm water beforehand, and add them to the solution in step (1). Stir at 300-400 rpm. Then dissolve ferrous sulfate and zinc sulfate in a small amount of water and slowly add them to the reaction system in batches. After the addition is complete, slowly adjust the pH of the system to 5.5-6.0 with dilute alkali solution and stir at a constant temperature for 40-50 min. (3) Slowly adjust the pH of the system to 7.5-8 with dilute alkali solution, mix the mulberry bark extract and scutellaria extract, dissolve in warm water, lower the reaction temperature to 40±2℃, add the mixed extract to the reaction system, and stir at 150-200 rpm for 20-25 min. (4) Slowly adjust the pH of the system to 5.5-6 with dilute acid solution, stir potassium humate with an appropriate amount of warm water to form a uniform slurry, add it to the solution in step (3), stir at a speed of 500-600 rpm, and continue to react for 30 min at 40±2℃. (5) Spray dry the obtained viscous slurry, set the inlet temperature to 130-140℃ and the outlet temperature to 85-90℃, quickly dry and shape it, collect the dried powder, and pass it through an 80-100 mesh sieve to obtain trace metal elements in the composite chelated state.

5. A method for preparing a water-soluble fertilizer containing macroelements as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) At a speed of 200-300 rpm and a temperature of 55-60℃, add water of 30-40% of the total weight of the raw materials, and then add urea, potassium nitrate, ammonium polyphosphate, potassium phosphite and sodium octaborate tetrahydrate in sequence. Stir and heat until completely dissolved to obtain the basic mother liquor. (2) Cool the base mother liquor to below 40°C, add the viscous slurry-like composite chelated trace metal elements, and stir until completely dispersed and uniform; (3) Spray granulation of the stirred slurry, and after sieving, obtain finished particles with a particle size of 1-4 mm. After the finished product passes the inspection, seal and moisture-proof packaging.

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