Process for producing chelate complexes of lignosulfonates

Abstract

The method for obtaining the chelate complex is carried out by nitrification of an aqueous solution of lignosulfonate in 30% - 55.0% by weight of nitric acid, while maintaining the temperature in the range of 25°C - 35°C. At no earlier than 30 minutes after the completion of the addition of nitric acid, a biogenic metal salt is added under continuous stirring, while maintaining the temperature in the range of 35°C to 50°C. After dissolving all the components, the solution is gradually stabilized by adding KOH or ammonia water, initially for 30 minutes until the pH reaches 3.0 - 3.5, and then for another 60 minutes until the pH reaches 4.5 - 5.5. The technical result of the invention consists in ensuring long-term stability of the solution form of the target complex at a high concentration of biogenic metals.

Description

Technical Field

[0001] This invention relates to a method for obtaining chelated complexes based on organic aminocarboxylic acid chelating agents and bio-derived metals. The use of chelated complexes significantly enhances the availability of micronutrients when used in agriculture as micronutrient fertilizers, in livestock farming of cattle and poultry as feed additives, and in the production of micronutrient additives for food. Background Technology

[0002] Aminocarboxylic acid complexes based on EDTA and glycine only perform the function of transporting nutrient metals, but they themselves are ballast compounds for soil, plants or animals. Meanwhile, EDTA salts are not permitted for use in the production of feed additives in Russia and the European Union. Compared with EDTA aminocarboxylic acid complexes, the chelated complexes of the proposed technology, which are based on nitrated lignin sulfonic acid, contain natural and valuable components of plant and animal nutrition in addition to chelation and transport functions: various amino acids and vitamins, fulvic acid-humic acid, and high molecular weight carbohydrates in the form of monosaccharides and polysaccharides[1],[2].

[0003] A key feature of the proposed technology is that manufacturers can forgo importing expensive EDTA and glycine aminocarboxylic acid chelating agents and independently produce the aminocarboxylic acid chelating agents within the same technology chain used for chelating complex production. Meanwhile, the raw material, technology-grade lignin sulfonate (LST), is a relatively inexpensive and readily available raw material used in the production of organic mineral fertilizers, growth promoters, feed and food additives, and even pharmaceuticals. These raw materials are produced and sold in large quantities in Russia, both for the domestic market and for export.

[0004] A method for producing iron lignin sulfonate chelates that can be used in agriculture and veterinary medicine is known according to patent RU 2165936 published on April 27, 2004, in which a chelating agent is mixed with a salt of ferrous or ferric iron, wherein nitrosated lignin sulfonic acid formed in the preparation stage of the chelate is used as the chelating agent, and iron salts are applied in both stages.

[0005] To achieve maximum iron chelation capacity, the remaining iron salt is added to the chelation solution after the nitrosation reaction is complete.

[0006] In patent RU 2660929, published on July 11, 2018, it is known that the organic component of the nutrient mixture for plants is synthesized using LST modified by nitrification with the aid of concentrated nitric acid. The nutrient mixture is synthesized as follows: 1 ml of concentrated nitric acid (63.6% concentration) is added to 100 ml of a 10% LST solution. The nitrification time is 60 minutes. After nitrification, the following nutrients are dissolved in the reaction mixture under stirring (in the initial LST weight percentages: FeSO4·7H2O -80; H3BO3 -7.4; ZnSO4·7H2O -14.2; CoCl2·6H2O -3.9; (NH4)6Mo7O 24 • H₂O -28.9; MnCl₂·4H₂O -11.6; MgSO₄·7H₂O -32.6; CuSO₄·5H₂O -12.6; Urea -100; K₂HPO₄·3H₂O -1.5). It is controlled by wheat germination. Germination takes 7 days, controlling the height of the new shoots and the length of the roots. The average plant height is 16.0 cm, and the total weight of all plants is 6.6 g (based on complete dry matter). Summary of the Invention

[0007] The technical challenge is to develop a continuous technology cycle for producing liquid chelate complexes with high chelating capacity based on an aminocarboxylic acid complexing agent, which is used as LST for nitration conversion mixed with cationic bio-derived metals.

[0008] The technical result of this method is to ensure the long-term stability of liquid chelate complexes with high concentrations of retained bio-derived metals.

[0009] The proposed method and the production of chelated complexes are characterized by an improved method based on technical-grade LST nitration that provides a continuous technical cycle, offering efficient chelation and cation retention with minimal foaming and separation of nitrogen oxides.

[0010] The nitration process is carried out under validated process conditions (time, temperature, sequence of action, kinetics) and at an optimal balance of selected active components in the reaction mixture. This makes it possible to ensure efficient complex formation and maintain the concentration of bio-derived metal ions at or above, and even exceeding, the results of other techniques used to produce chelate complexes.

[0011] The method for obtaining chelated complexes essentially involves nitrifying an aqueous solution of technical-grade lignin sulfonate (LST) with the aid of nitric acid, followed by the addition of an inorganic salt of a bio-derived metal.

[0012] The key parameters of this method (technique) are the equilibrium and concentration of the components, nitration time, temperature of the reaction mixture, dissolution rate and sequence of the bio-derived metal salt, and the time and method for stabilizing the solution until the final liquid chelate complex is obtained. Therefore, during the study, it was determined that the maximum reactivity of the chelation was observed when the bio-derived metal salt was added no earlier than 30 minutes after the addition of nitric acid.

[0013] Nitrification was carried out by adding 30.0% to 55.0% dilute nitric acid to a 15% to 20% LST aqueous solution under continuous mixing and maintaining the temperature between +25.0°C and +35.0°C. No earlier than 30 minutes after the addition of nitric acid, an inorganic bio-derived metal salt was added under continuous mixing and maintaining the temperature between +35.0°C and +50.0°C. After all components were dissolved, the solution was gradually stabilized by adding potassium hydroxide or ammonium hydroxide until the pH reached 3.0 to 3.5 within 30 minutes. Finally, after all components were dissolved, the solution was finally stabilized by adding potassium hydroxide or ammonium hydroxide for 60 minutes until the pH reached 4.5 to 5.5.

[0014] The addition of bio-derived metallic copper, zinc, manganese, iron, calcium, magnesium and cobalt inorganic salts, on an absolute dry matter (adm) basis, results in individual or total amounts up to 16% in the chelate complex.

[0015] To enhance biological activity, salts of fulvic humic acid are added to the solution under continuous stirring when the pH reaches 5.0 to 5.5; the content is as high as 15% on an absolute dry matter basis.

[0016] To enhance biological activity, when the pH reaches 5.0 to 5.5, melamine salt of bis(oxymethyl)phosphate is added to the solution under continuous stirring until its concentration in the solution reaches 10%. -6 % to 10 -7 %. Detailed Implementation

[0017] Example 1 Sample 1 was prepared using a multi-component composition based on sodium lignosulfonate to test its biological efficacy during pre-sowing treatment of winter wheat seeds.

[0018] • The preparation of multi-component trace element compositions was carried out in a laboratory equipped with a fume hood.

[0019] • Use a 2-liter glass reactor with heating capability and an adjustable magnetic stirrer.

[0020] • Add 30 ml of nitric acid (concentration 55.0%) to an 850 ml volume of 19% technical grade sodium lignosulfonate aqueous solution.

[0021] • At a given temperature of +25.0°C, the duration of nitration is 30 minutes.

[0022] • After nitration is complete, the temperature in the reactor is raised and maintained in the range of +35.0°C to 45.0°C.

[0023] • Under continuous mixing, the inorganic salts and boric acid of the biogenic metal “CP” are supplied in the following amounts: CoSO4·7H2O - 4.0 g, CuSO4·5H2O - 10.0 g, MnSO4·H2O - 25.0 g, ZnSO4·H2O - 25.0 g, FeSO4·7H2O - 50.0 g, MgSO4·7H2O - 25.0 g, H3BO3 - 10.0 g, (NH4)6Mo7O 24 ·4H2O - 1.0 g.

[0024] Each subsequent ingredient is added to the reaction mixture only after the previous one has been completely dissolved.

[0025] • After all components of the mixture have completely dissolved, turn off the reactor heating to reduce foaming and decrease the intensity of the mixture.

[0026] • The chelation was stabilized in the final stage by gradually adding ammonium hydroxide (25.0% concentration) to the reaction mixture.

[0027] • The first stabilization phase is carried out by adding 20 ml of ammonium hydroxide until the pH of the solution reaches 3.0 to 3.5, and mixing for about 30 minutes.

[0028] The second stabilization phase is carried out after the first phase is completed by adding the necessary amount of ammonium hydroxide to bring the pH of the solution to 4.8 to 5.2, and mixing for about 60 minutes.

[0029] • Throughout the stabilization phase, the pH of the aqueous solution was measured using a laboratory pH meter.

[0030] As a result of the reaction, a multi-component chelate complex of converted LST with the following component design values ​​was obtained: - Sulfur content - up to 2.0% - Total nitrogen content in the solution - up to 0.75% - Total dry matter content - 26.1% - Total biogenic metal content - 11.95% on absolute dry matter. - Boron content - 0.57% on absolute dry matter. - Molybdenum content - 0.17% on absolute dry matter. Among them, chelated: - Cobalt content - 0.27% on absolute dry matter. - Copper content - 0.82% on absolute dry matter. - Manganese content - 2.63% on absolute dry matter. - Zinc content - 2.94% on absolute dry matter. - Iron content - 3.73% on absolute dry matter. - Magnesium content - 0.81% on absolute dry matter. - Total organic matter content - 56.3% on absolute dry matter basis The resulting sample 1 was divided into two parts.

[0031] • Select the first portion, place it in a plastic bottle, and seal it for arbitration storage. Shelf life is 4 years. No precipitation, stratification, discoloration, or gas formation was observed during the entire storage period of sample 1.

[0032] The second part of the obtained sample was sent for bioactivity studies and laboratory testing.

[0033] Biological efficiency was tested in the field for the winter wheat seed variety “Adel” at Kuban State Agrarian University, named after ITTribulin[5]. Seed treatment was performed at a rate of 1 liter of sample per ton of seed before sowing.

[0034] The test results are given for two key indicators—yield and grain quality[6],[7].

[0035] 1. Yield increased from 42.2 c / ha to 45.9 c / ha, exceeding that of the control variety, which was 39.6 c / ha. HCP 05 -2.0 c / ha.

[0036] 2. The raw gluten content in the grains was 18.5%, compared to 17.0% in the control; the protein content in the grains was 14.8%, compared to 14.0% in the control.

[0037] Example 2 Sample 2 was prepared based on magnesium lignin sulfonate containing chelated iron to test its biological efficacy in the germination of barley hydroponic feed for cattle.

[0038] • Samples containing chelated iron(II) were prepared in a laboratory equipped with a fume hood.

[0039] • Use a 2-liter glass reactor with heating capability and an adjustable magnetic stirrer.

[0040] • Add 32 ml of nitric acid (concentration 52.5%) to an 800 ml volume of 18.5% magnesium lignosulfonate aqueous solution.

[0041] • At a given temperature of +28.0°C, the duration of nitration is 45 minutes.

[0042] • After nitration is complete, the temperature in the reactor is raised and maintained in the range of +40.0°C to 45.0°C.

[0043] • While stirring continuously, add 50 g of “FeSO4·7H2O”CP – 300.0 g.

[0044] • Each subsequent weight is added to the reaction mixture only after the previous one has been completely dissolved.

[0045] • After the ferric sulfate has completely dissolved, turn off the reactor heating to reduce foaming and decrease the intensity of mixing.

[0046] • The chelation was stabilized in the final stage by gradually adding ammonium hydroxide (25.0% concentration) to the reaction mixture.

[0047] • The first stabilization phase is carried out by adding 25 ml of ammonium hydroxide until the pH of the solution reaches 3.0 to 3.5, and mixing for about 35 minutes.

[0048] The second stabilization phase was carried out after the first phase by adding the necessary amount of ammonium hydroxide to bring the solution to pH 5.2 and mixing for 60 minutes.

[0049] • Throughout the stabilization phase, the pH of the aqueous solution was measured using a laboratory pH meter.

[0050] As a result of the reaction, a chelated iron complex with the following calculated component values ​​was obtained: - Sulfur content - up to 2.0% - Total nitrogen content in the solution - up to 0.7% - Total dry matter content - 30.6% - Iron content - 15.4% on absolute dry matter. - Total organic matter content - 44.5% on absolute dry matter basis The resulting sample 1 was divided into two parts.

[0051] • Select the first portion, place it in a plastic bottle, and seal it for arbitration storage. Shelf life is 3 years. No precipitation, stratification, discoloration, or gas formation was observed during the entire storage period of sample 1.

[0052] The second part of the obtained sample was sent for bioactivity studies and laboratory testing.

[0053] Biological efficiency of a sample 2 containing chelated iron and converted LST was tested for the barley seed variety "Borisfen," intended for winter feeding of cattle. Germination time on hydroponic devices was 7 days. The standard for using the sample containing chelated iron was 1 liter per 500-800 liters of working solution.

[0054] The quality characteristics of the germinated barley feed additive were tested in a veterinary laboratory in St. Petersburg.

[0055] The following results were obtained: 1. Increase the following: Vitamin B c -2.2 mg / kg (+13.0% compared to control), carotene 3.9 mg / kg (+17.0% compared to control), crude protein -1.86% (+4.5% compared to control), iron -6.4 mg / kg (+22.2% compared to control) 2. Improved quality characteristics of feed additives led to a 5% to 7% increase in milk production, improved cattle health, and improved digestibility of other feeds.

[0056] Example 3 Sample 3 was prepared using a multi-component composition based on calcium lignosulfonate to test its biological efficacy in laying hen feed.

[0057] The preparation of multi-component trace element compositions was carried out in a laboratory equipped with a fume hood.

[0058] Use a 2-liter glass reactor with heating capability and an adjustable magnetic stirrer.

[0059] Add 30 ml of nitric acid (concentration 30.0%) to a 900 ml volume of 17% technical grade calcium lignosulfonate aqueous solution.

[0060] At a given temperature of +25.0°C, the duration of nitration is 55 minutes.

[0061] After nitration is complete, the temperature in the reactor is raised and maintained in the range of +40.0°C to 45.0°C.

[0062] Under continuous mixing, the inorganic salts of the biogenic metal "CP" are supplied in the following amounts: MnSO4·H2O-50.0 g, ZnSO4·H2O-40.0 g, FeSO4·7H2O-50.0 g, MgSO4·7H2O-50.0 g. 4· 7H2O-50.0 g.

[0063] Each subsequent ingredient is added to the reaction mixture only after the previous one has been completely dissolved.

[0064] After all components of the mixture have completely dissolved, turn off the reactor heating to reduce foaming and decrease the intensity of the mixture.

[0065] The chelation was stabilized in the final stage by gradually adding potassium hydroxide (37.0%) to the reaction mixture.

[0066] The first stabilization phase is carried out by adding 10 ml of potassium hydroxide until the pH of the solution reaches 3.0 to 3.5, and mixing for about 30 minutes.

[0067] The second stabilization phase is carried out after the first phase is completed by adding the necessary amount of potassium hydroxide to bring the pH of the solution to 4.9 to 5.3, and mixing for 60 minutes.

[0068] • Throughout the stabilization phase, the pH of the aqueous solution was measured using a laboratory pH meter.

[0069] As a result of the reaction, a multi-component chelate complex of converted LST with the following component design values ​​was obtained: - Sulfur content - up to 2.0% - Total nitrogen content in the solution - up to 0.4% - Total dry matter content - 29.1% - Total biogenic metal content - 15.0% on absolute dry matter. - Manganese content - 4.8% on absolute dry matter. - Zinc content - 4.3% on absolute dry matter. - Iron content - 3.4% on absolute dry matter. - Magnesium content - 1.5% on absolute dry matter. - Calcium content - 1.0% on absolute dry matter. - Total organic matter content - 52.0% on absolute dry matter basis The resulting sample 3 was divided into two parts.

[0070] • Select the first portion, place it in a plastic bottle, and seal it for arbitration storage. Shelf life is 3 years. No precipitation, stratification, discoloration, or gas formation was observed throughout the storage period of sample 3.

[0071] The second part of the obtained sample was sent for bioactivity studies and laboratory testing.

[0072] Biological efficiency was tested on chickens allocated for slaughter and showing no or significantly reduced egg production at poultry farms in the Leningrad region. A 5% aqueous solution was prepared from the samples and fed to the samples for 6 days during the drinking period.

[0073] The test results showed an increase or recovery in egg production.

[0074] Example 4 Sample 4 was prepared using a multi-component composition based on calcium lignin sulfonate to evaluate the effect of converted lignin sulfonate containing bioactive trace elements in chelated form on soil desalination.

[0075] • The preparation of multi-component trace element compositions was carried out in a laboratory equipped with a fume hood.

[0076] • Use a 2-liter glass reactor with heating capability and an adjustable magnetic stirrer.

[0077] • Add 35 ml of nitric acid (concentration 55.0%) to a 900 ml volume of 15% technical grade calcium lignosulfonate aqueous solution.

[0078] • At a given temperature of +30.0°C, the duration of nitration is 35 minutes.

[0079] • After nitration is complete, the temperature in the reactor is raised and maintained in the range of +40.0°C to 50.0°C.

[0080] • Under continuous stirring, supply the following amounts of biogenic metal "CP" inorganic salts: CoSO4·7H2O 5.0 g, CuSO4·5H2O 15.0 g, MnSO4·H2O 25.0 g, ZnSO4·H2O 25.0 g, FeSO4·7H2O 30.0 g, MgSO4·7H2O 50.0 g, H3BO3 15.0 g, (NH4)6Mo7O 24 ·4H2O-2.0 g.

[0081] Each subsequent ingredient is added to the reaction mixture only after the previous one has been completely dissolved.

[0082] • After all components of the mixture have completely dissolved, turn off the reactor heating to reduce foaming and decrease the intensity of the mixture.

[0083] • The chelation was stabilized in the final stage by gradually adding ammonium hydroxide (25.0% concentration) to the reaction mixture.

[0084] • The first stabilization phase is carried out by adding 30 ml of potassium hydroxide until the pH of the solution reaches 3.0 to 3.5, and mixing for about 40 minutes.

[0085] The second stabilization phase is carried out after the first phase by adding the necessary amount of ammonium hydroxide to bring the pH of the solution to 5.0 to 5.2, and mixing for approximately 60 minutes. • After stabilization with continuous stirring and the pH of the solution is 5.0 to 5.2, add 100 ml of 15% fulvic acid-humate aqueous solution until the components are completely dissolved.

[0086] • Throughout the stabilization phase, the pH of the aqueous solution was measured using a laboratory pH meter.

[0087] As a result of the reaction, in the case of the addition of the fulvic acid-humic acid composition, a multi-component chelate complex of converted LST with the following calculated values ​​of components was obtained: - Sulfur content - up to 2.2% - Total nitrogen content in the solution - up to 0.8% - Total dry matter content - 27.5% - Total biogenic metal content - 13.1% on absolute dry matter. - Boron content - 0.8% on absolute dry matter. - Molybdenum content - 0.3% on absolute dry matter. Among them, chelated: - Manganese content - 2.5% on absolute dry matter. - Zinc content - 2.8% on absolute dry matter. - Iron content - 2.2% on absolute dry matter. - Magnesium content - 1.5% on absolute dry matter. - Calcium content - 1.5% on absolute dry matter. - Cobalt content - 0.3% on absolute dry matter. - Copper content - 1.2% on absolute dry matter. - Fulvic acid-humate content - 14.8% on absolute dry matter. - Total organic matter content - 54.0% on absolute dry matter basis The resulting sample 4 was divided into two parts.

[0088] • Select the first portion, place it in a plastic bottle, and seal it for arbitration storage. Shelf life is 3 years. No precipitation, stratification, discoloration, or gas formation was observed throughout the storage period of sample 4.

[0089] The second part of the obtained sample was sent for bioactivity studies and laboratory testing.

[0090] An assessment of the impact of samples on soil salinization was conducted at the Astrakhan Region Branch of the Russian Agricultural Center.

[0091] Experiments were conducted on soils with varying salinity levels (medium, weakly saline, and strongly saline, with low humus content). The application rate and guidelines for the sample treatments were four treatments per growing season, with an equivalent application rate of 5 l / ha.

[0092] The results are shown in Table 1.

[0093]

[0094] An increase in soil humus supply was observed at all three sites, with an average increase of 63%.

[0095] The average soil environmental response level decreased from 7.5 to 6.2 (a decrease of about 17%), which changed the soil acidity level from neutral and slightly alkaline to slightly acidic.

[0096] A decrease in soil salinity was observed at all three locations.

[0097] Example 5 Sample 5 was prepared using a sodium lignosulfonate-based multicomponent composition to test the biological efficacy of pre-planting treatment for maize seeds. Sample 5 was prepared according to the formulation of Sample 1 by adding a melamine salt of bis(oxymethyl)phosphate to the finished liquid multicomponent trace element composition.

[0098] In a finished liquid trace element chelate composition at +25.00°C and a volume of 980 ml, 20 ml of a 10% concentration was added under continuous stirring. -4 % melamine salt bis(oxymethyl)phosphoric acid aqueous solution.

[0099] A complete and homogeneous mixture was achieved after 30 minutes of magnetic stirring, with the melamine salt content of bis(oxymethyl)phosphoric acid in the aqueous solution being 0.5 × 10⁻⁶. -7 %.

[0100] At Kuban State Agricultural University, named IT Tribulin, comparative verification of the biological efficacy of the formulation according to Example 5 was conducted based on comparative biological tests on maize seeds.

[0101] Biological testing was conducted by germinating seeds in 0.05% solutions of Samples 1 and 5. As a control, the test results for Sample 1 were obtained using distilled water and without the addition of melamine salt bis(oxymethyl)phosphate.

[0102] The increased bioactivity of samples 1 and 5 was confirmed by the increase in the weight of maize shoots; the results are shown in Table 2.

[0103] Table 2. Effects of samples based on multi-component trace element compositions on maize seed processing efficiency. Industrial applicability

[0104] In the above embodiments, it is shown that the gradual stabilization process of the resulting solution resulted in the fact that no precipitation, stratification, discoloration, or gas formation was observed during storage for 3 to 4 years.

[0105] This method reduces emissions of volatile nitrogen compounds by lowering the concentration of nitric acid and reducing the volume of ammonium hydroxide or by completely replacing ammonium hydroxide with potassium hydroxide, as well as shortening the nitration time, which is an important environmental aspect when implementing the technology on an industrial scale.

[0106] In the prototype method according to patent RU2660929, there is no stage for stabilizing the resulting nutrient mixture. Simultaneously adding ammonia to pH 4 to 6 is insufficient to obtain a completely homogeneous solution, which may lead to precipitation during storage, i.e., insufficient stability.

[0107] A key feature of the technology already available for producing chelated complexes is the ability to create our own aminocarboxylic acid chelating agent production based on a single technology process, enabling us to forgo expensive imported EDTA and glycine aminocarboxylic acid chelating agents without sacrificing production capacity, as the concentration of chelated bio-based metals reaches 16% on absolute dry matter. References 1) FEBrowns and DABrown, "Lignin Chemistry", "Forest Industry", Moscow,1964.UDC 668.474:54 2) KV Sarkanen and KHLudwig, "Lignins", "Forest Industry", Moscow, 1975. UDC 634.0.813.11 3) N.I.Afanasyef,S.E.Tel'tevskaya,N.A.Makarevich,L.N.Parfenova,“Structure and Physicochemical Properties of Lignosulfonates”Ural Branch ofthe Russian Academy of Sciences,Yekaterinburg,2005.UDC541.183:634.0.864 4) M.I.Chudakov,“Industrial Use of Lignin”,“Forest Industry”,Moscow,1972. UDC 634.0.864 5) DospekhovB.A.FieldExperimentMethodology / B.A.Dospekhov.-M.:Kolos,1985 6) Barchukova A.Ya. Efficiency of Growth Regulators in Winter WheatCultivation Technology / A.Ya. Barchukova, Ya.K. Tosunov, N.V. Chernysheva,S.G.Fat. Proceedings of the Kuban Agrarian University,2009 7) Kodanev I.V.Improving Grain Quality / I.V. Kodanev.-M.: Kolos,1976.

Claims

1. A method for obtaining chelated complexes, comprising converting technical-grade lignin sulfonate by nitration with nitric acid followed by the addition of an inorganic salt of a bio-derived metal, characterized in that, The nitration of lignin sulfonate was carried out by adding 30.0% to 55.0% dilute nitric acid to a 15% to 20% aqueous solution of lignin sulfonate under continuous stirring while maintaining the temperature in the range of +25.0°C to +35.0°C. No earlier than 30 minutes after the addition of nitric acid, an inorganic bio-derived metal salt was added under continuous stirring while maintaining the temperature in the range of +35.0°C to +50.0°C. After all components were dissolved, the solution was gradually stabilized by adding potassium hydroxide or ammonium hydroxide until the pH reached 3.0 to 3.5 within 30 minutes. After all components were dissolved, the solution was finally stabilized by adding potassium hydroxide or ammonium hydroxide for 60 minutes until the pH reached 4.5 to 5.

5.

2. The method according to claim 1, wherein the inorganic salts of the bio-derived metals copper, zinc, manganese, iron, calcium, magnesium, and cobalt added, on an absolute dry matter basis, have an individual or total content of up to 16%.

3. The method according to claim 1, wherein, in order to improve biological activity, a fulvic acid-humic acid salt is added to the solution under continuous stirring when the pH reaches 5.0 to 5.5; the salt content is up to 15% on an absolute dry matter basis.

4. The method according to claim 1, wherein, to improve biological activity, when the pH reaches 5.0 to 5.5, melamine salt of bis(oxymethyl)phosphate is added to the solution under continuous stirring until its content in the solution is 10. -6 % to 10 -7 %.

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