A humic acid compound fertilizer with micronutrient synergistic effect and its production method

Abstract

This invention discloses a humic acid compound fertilizer with micronutrient enhancement functions and its production method. The compound fertilizer is made from 20-40 parts of biochemical humic acid chelated micronutrient fermentation product, 45-65 parts of macronutrient fertilizer, and 5-15 parts of auxiliary materials. The fermentation product uses agricultural waste and micronutrient mineral raw materials as substrates, and is obtained through stepwise solid-state fermentation using a compound microbial agent composed of *Bacillus belye*, *Ornithine Aureus*, and *Lactobacillus acidophilus*. This invention can significantly improve the activity of humic acid and the chelation rate and absorption and utilization rate of micronutrients, while also providing soil improvement and crop growth promotion effects. The process is green and environmentally friendly, and suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of microbial and bio-organic fertilizer technology, specifically relating to a humic acid compound fertilizer with micronutrient enhancement function and its production method. Background Technology

[0002] Humic acid is a class of natural organic macromolecules with functions such as complexation and chelation, adsorption and slow release, soil improvement, and growth promotion and stress resistance. It is divided into two main categories: mineral-derived humic acid and biochemical humic acid. Biochemical humic acid, prepared from agricultural organic waste through microbial fermentation, has advantages such as wide availability of raw materials, low production cost, good water solubility, and high biological activity. It is a core green raw material to replace non-renewable mineral-derived humic acid and a research hotspot in the fertilizer field. Micronutrients (calcium, magnesium, zinc, iron, boron, copper, molybdenum, etc.) are essential nutrients for crop growth and development, participating in key physiological processes such as photosynthesis, enzyme system activation, stress resistance regulation, and carbohydrate synthesis and transport. Their deficiency directly leads to decreased crop yield, deterioration in quality, and a sharp reduction in stress resistance. Furthermore, micronutrients are easily fixed by soil colloids, resulting in low crop absorption and utilization rates, which has long been a major industry challenge restricting agricultural production.

[0003] Existing technologies for fertilizer products that combine humic acid with trace elements mainly suffer from the following core technological defects, failing to achieve a high-efficiency improvement in the absorption and utilization of trace elements: 1. Insufficient activity and weak chelating ability of humic acid: native humic acid has a large molecular weight, stable aromatic ring structure, few active functional groups, poor water solubility, few chelating sites for micronutrients and weak binding force. Conventional physical compounding cannot form stable chelates. Micronutrients are easily fixed by phosphate and carbonate after being applied to the soil, with a fixation rate of over 80% and extremely low absorption and utilization rate.

[0004] 2. Existing microbial fermentation technologies have significant shortcomings: Current humic acid fermentation technologies mostly use single strains, which can only achieve the initial degradation of humic acid and cannot simultaneously achieve the targeted enrichment of functional groups, resulting in low fulvic acid conversion rates. Furthermore, there are antagonistic issues when fungi and bacteria are fermented together, and the functions of the strains cannot be coordinated, failing to meet the three core needs of humic acid degradation, micronutrient activation, and crop growth promotion.

[0005] 3. Separation of fermentation and chelation processes, resulting in poor synergy: Existing technologies mostly involve adding chemical chelating agents and trace elements after humic acid fermentation, which not only increases process costs and environmental risks, but also fails to utilize natural chelating ligands such as organic acids and extracellular polysaccharides produced during fermentation, making it impossible to achieve multi-ligand synergistic chelation and resulting in poor chelation stability; at the same time, the high-temperature chelation process will cause all functional microorganisms to be inactivated, and they will not be able to play a role in activating rhizosphere nutrients.

[0006] Therefore, developing a humic acid compound fertilizer that can target and enhance the chelating activity of humic acid, achieve simultaneous fermentation and chelation, balance the function of microorganisms, and improve the absorption and utilization rate of micronutrients is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a humic acid compound fertilizer with the function of enhancing the efficacy of trace elements and its production method, so as to solve the problems of weak humic acid chelation activity, single function of fermentation strains, separation of fermentation and chelation processes, and low utilization rate of trace elements in the existing technology.

[0008] To achieve the above objectives, this invention provides a humic acid compound fertilizer with the function of enhancing the efficacy of trace elements. Its core innovation lies in the construction of a specific ternary compound microbial fermentation system composed of Bacillus belyssae, Ornithine aureus and Lactobacillus acidophilus. Using this system as a biological engine, the efficient and directional conversion of humic acid and the in-situ deep chelation of trace elements are achieved in one step during the stepwise solid-state fermentation process.

[0009] A humic acid compound fertilizer with enhanced micronutrient and trace element effects is made from the following raw materials in parts by weight: 20-40 parts of biochemical humic acid chelated micronutrient fermentation product, 45-65 parts of macronutrient fertilizer, and 5-15 parts of auxiliary materials; the biochemical humic acid chelated micronutrient fermentation product is obtained by mixing agricultural waste, micronutrient and trace element mineral raw materials, and a compound microbial fermentation agent, followed by stepwise solid-state fermentation; the compound microbial fermentation agent is Bacillus belesiensis (…). Bacillus velezensis ), Ornithine Bacillus aureus ( Ornithinibacter aureus ) and Lactobacillus acidophilus ( Lactobacillus acidophilus )composition.

[0010] Furthermore, the macro-element fertilizer is a compound combination of urea, monoammonium phosphate and potassium sulfate, with a mass ratio of (20-30):(15-25):(10-20).

[0011] Furthermore, the auxiliary material is a mixture of attapulgite, zeolite powder and diatomaceous earth, with a mass ratio of (4-8):(3-7):(2-5).

[0012] Furthermore, in the compound microbial fermentation agent, the strain number of *Bacillus belyssus* is CGMCC No. 1.7417, purchased from the China General Microbiological Culture Collection Center, with an original preservation date of March 1, 2008; the strain number of *Ornithine aureus* is CGMCC No. 1.10341, with an original preservation date of December 21, 2009, purchased from the China General Microbiological Culture Collection Center; and the strain number of *Lactobacillus acidophilus* is CGMCC No. 1.12735, purchased from the China General Microbiological Culture Collection Center, with an original preservation date of December 17, 2013. In the compound microbial fermentation agent, the seed liquid volume ratio of *Bacillus belyssus*, *Ornithine aureus*, and *Lactobacillus acidophilus* is (3-5):(2-4):(1-3), and the total effective viable count of the compound microbial agent is ≥20 billion CFU / g. The preparation method of the compound microbial fermentation agent is as follows: (1) Activation of strains: The freeze-dried bacterial powders of Bacillus belye, Ornithine aureus, and Lactobacillus acidophilus were inoculated onto the corresponding slant culture media and activated by constant temperature culture to obtain activated slant strains; Bacillus belye and Ornithine aureus were cultured on LB solid medium at 30-32℃ for 24-48h; Lactobacillus acidophilus was cultured on MRS solid medium at 35-38℃ for 24-48h. (2) Seed culture preparation: Each activated slant strain was inoculated into the corresponding liquid culture medium. Bacillus belye and Ornithine Bacillus aureus were cultured at 30-32℃ and 180r / min for 24-36h with shaking. Lactobacillus acidophilus was cultured at 35-38℃ with static anaerobic culture for 24-36h to obtain the seed culture of each strain. The effective viable count in each seed culture was ≥1 billion CFU / mL. (3) Preparation of compound microbial agent: The seed liquids of Bacillus belyssus, Ornithine viridissus, and Lactobacillus acidophilus are mixed thoroughly according to the volume ratio of (3-5):(2-4):(1-3) to obtain a compound seed liquid. The compound seed liquid is then inoculated into the sterilized solid fermentation medium at an inoculation rate of 5%-10% (m / m). The mixture is fermented at a constant temperature of 30-35℃ for 48-72 hours. After the fermentation is completed, the mixture is dried and pulverized at a low temperature below 40℃ and passed through a 40-mesh sieve to obtain the compound microbial fermentation agent.

[0013] Furthermore, in step (2), the liquid culture medium used for Bacillus belyssus and Ornithine aureus is LB liquid culture medium, and the liquid culture medium used for Lactobacillus acidophilus is MRS liquid culture medium; in step (3), the solid fermentation culture medium is composed of the following components by weight: 60-70 parts wheat bran, 15-25 parts corn flour, 8-15 parts soybean meal, 2-5 parts glucose, 0.1-0.3 parts magnesium sulfate, and 0.2-0.5 parts dipotassium hydrogen phosphate; when preparing the mixture, mix the raw materials according to the ratio, add deionized water to adjust the water content of the system to 45%-55%, adjust the pH value to 6.5-7.0, sterilize by high pressure steam at 121℃ for 30 minutes, and cool to room temperature for later use.

[0014] Furthermore, the agricultural waste is mushroom residue, crushed to a particle size of 2-5 mm; the trace element mineral raw materials are a combination of calcium, magnesium, zinc, iron, manganese, and copper sources, wherein the mass ratio of available calcium, magnesium, zinc, iron, manganese, and copper is (10-20):(5-15):(2-5):(2-5):(1-3):(0.5-1). The mass ratio of agricultural waste to trace element mineral raw materials is (80-90):(10-20). The calcium source is at least one of calcium-based bentonite and dolomite powder; the magnesium source is at least one of dolomite powder and magnesite powder; the zinc source is zinc sulfate; the iron source is ferrous sulfate; the manganese source is manganese sulfate; and the copper source is copper sulfate.

[0015] Furthermore, the stepwise solid-state fermentation preparation method of the biochemical humic acid chelated trace element fermentation product includes the following steps: (1) Raw material pretreatment: crush agricultural waste to a particle size of 2-5 mm, mix it evenly with trace element mineral raw materials according to the ratio, adjust the pH of the system to 6.5-7.5 with citric acid or sodium hydroxide, and add water to the system to a moisture content of 55%-65% to obtain fermentation base material; the mass ratio of agricultural waste to trace element mineral raw materials is (80-90):(10-20); (2) Primary mesophilic aerobic directional conversion fermentation: 70% of the total inoculum amount of the compound microbial fermentation agent is inoculated into the fermentation substrate, and after being thoroughly mixed, it is sent to the solid fermentation tank for primary aerobic fermentation. The fermentation temperature is controlled at 30-35℃, the fermentation time is 48-72h, and the pile is turned and aerated once every 12h to maintain the dissolved oxygen content of the system ≥5mg / L. (3) Secondary mesophilic micro-anaerobic in-situ chelation fermentation: After the primary fermentation is completed, the remaining 30% of the compound microbial fermentation agent is inoculated into the fermentation system, thoroughly mixed, and gently turned and aerated once every 24 hours to maintain the dissolved oxygen content of the system at 0.5-1 mg / L. The fermentation temperature is controlled at 32-37℃ and the fermentation time is 48-72 hours. (4) Three-stage low-temperature post-fermentation stabilization: After the two-stage chelation fermentation is completed, the pile temperature is maintained at 40-45℃ for post-fermentation for 48-72 hours. The pile is turned over once every 24 hours. When the pile temperature naturally drops to room temperature, the fermentation is completed. (5) Post-processing of the product: After fermentation, the material is spread out to room temperature, dried and crushed at a low temperature below 40°C, and passed through a 60-mesh sieve to obtain the biochemical humic acid chelated trace element fermentation product.

[0016] Furthermore, the total inoculum amount of the compound microbial fermentation agent is 0.5%-2.0% of the total mass of the fermentation substrate.

[0017] A method for producing a humic acid compound fertilizer with micronutrient enhancement function includes the following steps: (1) Preparation of biochemical humic acid chelated micronutrient fermentation products; (2) Weigh out the biochemical humic acid chelated micronutrient fermentation product, macronutrient fertilizer and auxiliary materials according to the weight ratio, crush them separately and pass them through an 80-mesh sieve, and set them aside. (3) Send the sieved raw materials into a twin-shaft paddle mixer and mix them thoroughly for ≥20 minutes to obtain a uniformly mixed base powder. (4) The base powder is fed into the rotary drum granulator, and saturated steam is introduced to adjust the moisture content and temperature of the material. The granulation temperature is controlled at 60-70℃ and the particle size of the formed particles is controlled at 2-4mm. After granulation, the particles are cooled, dried and screened to obtain the humic acid compound fertilizer with the function of enhancing the effects of trace elements.

[0018] Beneficial effects: The core of the invention lies in the combination of three specific microorganisms and their unique division of labor and synergistic mechanism.

[0019] Bacillus bellis can rapidly colonize and multiply, efficiently degrading lignocellulosic macromolecules in agricultural waste while releasing small-molecule organic acids, providing active precursors and chelating ligands for subsequent reactions. Ornithine Bacillus aureus can directionally oxidize and degrade organic matter, enriching active functional groups such as carboxyl and phenolic hydroxyl groups, significantly improving the conversion rate of humic acid, especially fulvic acid, and greatly increasing the chelation binding sites for micronutrients. Lactobacillus acidophilus can continuously produce acidic metabolites such as lactic acid in the middle and late stages of fermentation. On the one hand, it maintains the weakly acidic environment of the system, activates micronutrient minerals, and promotes chelation reactions. On the other hand, it inhibits the growth of other bacteria, avoids the antagonistic problem of microbial strains in compound fermentation, and ensures the stable operation of the entire fermentation system. The three functional bacteria work together to simultaneously complete the degradation of agricultural waste, the targeted conversion and activation of humic acid, the in-situ activation of trace elements and minerals, and the synergistic chelation of multiple ligands in a stepwise solid-state fermentation system, producing stable biochemical humic acid chelated trace element fermentation products. No additional chemical chelating agents are needed, and there is no need to carry out fermentation and chelation processes separately, which simplifies the production process and reduces costs and environmental risks.

[0020] The biochemical humic acid chelated micronutrient fermentation product prepared by this invention contains fulvic acid accounting for more than 45% of the total humic acid content, with a total carboxyl + phenolic hydroxyl group content ≥8.0 mmol / g. The chelation rate for micronutrients can reach over 85%. The chelated product exhibits good stability and, when applied to the soil, effectively prevents micronutrients from being fixed by soil colloids or phosphate and carbonate ions, significantly improving the bioavailability of micronutrients. Simultaneously, some functional live bacteria survive after fermentation, continuously activating fixed micronutrients in the soil after application to the rhizosphere, further enhancing nutrient absorption and utilization, and synergistically achieving enhanced micronutrient efficacy. The humic acid compound fertilizer obtained by this invention has balanced nutrients and combines the multiple functions of humic acid in improving soil, promoting growth and stress resistance, and efficiently supplementing micronutrients. It has a wide range of raw material sources, a simple and green production process, is suitable for large-scale industrial production, and has broad application prospects. Attached Figure Description

[0021] Figure 1 This image shows the co-culture status of Bacillus belyssus (CGMCC No. 1.7417), Ornithine Aureobacterium tumefaciens (CGMCC No. 1.10341), and Lactobacillus acidophilus (CGMCC No. 1.1273) of this invention. 1 represents a Bacillus belyssus colony, 2 represents an Ornithine Aureobacterium tumefaciens colony, and 3 represents a Lactobacillus acidophilus colony. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to specific embodiments, but it is not limited thereto.

[0023] In the following examples and comparative examples, all strains used were purchased from the China General Microbiological Culture Collection Center (CGMCC). Specific information is as follows: Bacillus velezensis, strain number CGMCC No. 1.7417; Ornithinibacterium aureus, strain number CGMCC No. 1.10341; Lactobacillus acidophilus, strain number CGMCC No. 1.12735; all strains used can be purchased openly through the depository center without the need for biological preservation.

[0024] The culture medium formula used is as follows: 1. LB solid medium: 10 g / L peptone, 5 g / L yeast extract, 10 g / L sodium chloride, 18 g / L agar powder, deionized water as solvent, pH adjusted to 7.0-7.2, autoclaved at 121℃ for 20 min; 2. LB liquid medium: The formula is the same as LB solid medium, except that the agar powder is removed, and all other parameters are the same; 3. MRS solid culture medium: peptone 10g / L, beef extract 10g / L, yeast extract 5g / L, glucose 20g / L, Tween-80 1mL / L, dipotassium hydrogen phosphate 2g / L, sodium acetate 5g / L, triammonium citrate 2g / L, magnesium sulfate 0.58g / L, manganese sulfate 0.25g / L, agar powder 18g / L, solvent is deionized water, pH value adjusted to 6.2-6.4, autoclave at 115℃ for 20min; 4. MRS liquid culture medium: The formula is the same as that of MRS solid culture medium, except that the agar powder is removed, and the other parameters are the same. 5. Solid fermentation medium: by weight, 65 parts wheat bran, 20 parts corn flour, 10 parts soybean meal, 3 parts glucose, 0.2 parts magnesium sulfate, and 0.3 parts dipotassium hydrogen phosphate; mix the raw materials according to the ratio, add deionized water to adjust the water content of the system to 50%, adjust the pH value to 6.8, autoclave at 121℃ for 30 minutes, and cool to room temperature before use.

[0025] Example 1 This embodiment provides a humic acid compound fertilizer with the function of enhancing the efficacy of micronutrients, which is made from the following raw materials in parts by weight: 30 parts of biochemical humic acid chelated micronutrient fermentation product, 55 parts of macronutrient fertilizer, and 10 parts of auxiliary materials.

[0026] The main fertilizer is a compound of urea, monoammonium phosphate and potassium sulfate, with a mass ratio of 25:20:15; the auxiliary material is a mixture of attapulgite, zeolite powder and diatomaceous earth, with a mass ratio of 6:5:3.

[0027] Step 1: Preparation of compound microbial fermentation agent (1) Activation of strains: The freeze-dried bacterial powders of Bacillus belye, Ornithine aureus and Lactobacillus acidophilus were inoculated onto the corresponding slant culture medium and activated by constant temperature culture to obtain activated slant strains; Bacillus belye and Ornithine aureus were cultured on LB solid medium at 30-32℃ for 36h; Lactobacillus acidophilus was cultured on MRS solid medium at 35-38℃ for 36h. (2) Seed culture preparation: Each activated slant strain was inoculated into the corresponding liquid culture medium. Bacillus belye and Ornithine Bacillus aureus were cultured at 30-32℃ and 180r / min for 30h with shaking. Lactobacillus acidophilus was cultured at 35-38℃ with static anaerobic culture for 30h to obtain the seed culture of each strain. The effective viable count in each seed culture was ≥1 billion CFU / mL. (3) Preparation of compound microbial agent: The seed liquids of Bacillus belysae, Ornithine aureus and Lactobacillus acidophilus are mixed thoroughly in a volume ratio of 4:3:2 to obtain a compound seed liquid; the compound seed liquid is then inoculated into the sterilized solid fermentation medium at an inoculation rate of 8%, and solid fermented at a constant temperature of 30-35℃ for 60h. After fermentation, the mixture is dried and pulverized at a low temperature below 40℃ and passed through a 40-mesh sieve to obtain the compound microbial fermentation agent. The total effective viable count of the compound microbial agent is ≥20 billion CFU / g.

[0028] Step 2: Preparation of fermentation products containing trace elements in biochemical humic acid chelate form The product is prepared using a stepwise solid-state fermentation process, and the specific steps are as follows: (1) Raw material pretreatment: Agricultural waste mushroom residue is crushed to a particle size of 2-5 mm and mixed evenly with trace element mineral raw materials at a mass ratio of 85:15; the trace element mineral raw materials are a combination of calcium source, magnesium source, zinc source, iron source, manganese source and copper source, wherein the mass ratio of available calcium, magnesium, zinc, iron, manganese and copper elements is 15:10:3:3:2:0.8; the calcium source is calcium-based bentonite, the magnesium source is dolomite powder, the zinc source is zinc sulfate, the iron source is ferrous sulfate, the manganese source is manganese sulfate and the copper source is copper sulfate. The pH of the system is adjusted to 7.0 with citric acid or sodium hydroxide, and water is added until the system moisture content is 60% to obtain the fermentation base material; (2) Primary mesophilic aerobic directional conversion fermentation: 70% of the total inoculum amount of the compound microbial fermentation agent is inoculated into the fermentation substrate (the total inoculum amount of the compound microbial fermentation agent is 1.0% of the total mass of the fermentation substrate). After thorough mixing, it is sent to the solid fermentation tank for primary aerobic fermentation. The fermentation temperature is controlled at 30-35℃, the fermentation time is 48h, and the pile is turned and aerated once every 12h to maintain the dissolved oxygen content of the system ≥5mg / L. (3) Secondary mesophilic micro-anaerobic in-situ chelation fermentation: After the primary fermentation is completed, the remaining 30% of the compound microbial fermentation agent is inoculated into the fermentation system, thoroughly mixed, and gently turned and aerated once every 24 hours to maintain the dissolved oxygen content of the system at 0.5-1 mg / L. The fermentation temperature is controlled at 32-37℃ and the fermentation time is 48 hours. (4) Three-stage low-temperature post-fermentation stabilization: After the two-stage chelation fermentation is completed, the pile temperature is maintained at 40-45℃ for post-fermentation for 48 hours. The pile is turned over once every 24 hours. When the pile temperature naturally drops to room temperature, the fermentation is completed. (5) Post-processing of the product: After fermentation, the material is spread out to room temperature, dried at a low temperature below 40°C, crushed, and passed through a 60-mesh sieve to obtain the biochemical humic acid chelated trace element fermentation product.

[0029] Step 3: Preparation of humic acid compound fertilizer (1) Weigh the above biochemical humic acid chelated micronutrient fermentation products, macronutrient fertilizers and auxiliary materials according to the weight ratio, crush them separately and pass them through an 80-mesh sieve for later use; (2) The sieved raw materials are fed into a twin-shaft paddle mixer and mixed thoroughly for 25 minutes to obtain a uniformly mixed base powder. (3) The base powder is fed into the rotary drum granulator, and saturated steam is introduced to adjust the moisture content and temperature of the material. The particle size of the formed particles is controlled at 2-4 mm. After granulation, the particles are cooled, dried and screened to obtain the humic acid compound fertilizer of this embodiment.

[0030] Example 2 This embodiment provides a humic acid compound fertilizer with the function of enhancing the efficacy of micronutrients, which is made from the following raw materials in parts by weight: 20 parts of biochemical humic acid chelated micronutrient fermentation product, 65 parts of macronutrient fertilizer, and 15 parts of auxiliary materials.

[0031] The main fertilizer is a compound of urea, monoammonium phosphate and potassium sulfate, with a mass ratio of 20:15:10; the auxiliary material is a mixture of attapulgite, zeolite powder and diatomaceous earth, with a mass ratio of 4:3:2.

[0032] Step 1: Preparation of compound microbial fermentation agent (1) Activation of strains: The freeze-dried bacterial powders of Bacillus belye, Ornithine aureus and Lactobacillus acidophilus were inoculated onto the corresponding slant culture medium and activated by constant temperature culture to obtain activated slant strains; Bacillus belye and Ornithine aureus were cultured on LB solid medium at 30-32℃ for 48h; Lactobacillus acidophilus was cultured on MRS solid medium at 35-38℃ for 48h. (2) Seed culture preparation: Each activated slant strain was inoculated into the corresponding liquid culture medium. Bacillus bellis and Ornithine Bacillus were cultured at 30-32℃ and 180r / min for 36h with shaking. Lactobacillus acidophilus was cultured at 35-38℃ with static anaerobic culture for 36h to obtain the seed culture of each strain. The effective viable count in each seed culture was ≥1 billion CFU / mL. (3) Preparation of compound microbial agent: The seed liquids of Bacillus belysae, Ornithine aureus and Lactobacillus acidophilus are mixed thoroughly in a volume ratio of 3:2:1 to obtain a compound seed liquid; the compound seed liquid is then inoculated into the sterilized solid fermentation medium at an inoculation rate of 5%, and solid fermented at a constant temperature of 30-35℃ for 72h. After fermentation, the mixture is dried and pulverized at a low temperature below 40℃ and passed through a 40-mesh sieve to obtain the compound microbial fermentation agent. The total effective viable count of the compound microbial agent is ≥20 billion CFU / g.

[0033] Step 2: Preparation of fermentation products containing trace elements in biochemical humic acid chelate form The product is prepared using a stepwise solid-state fermentation process, and the specific steps are as follows: (1) Raw material pretreatment: Agricultural waste mushroom residue is crushed to a particle size of 2-5 mm and mixed with trace element mineral raw materials at a mass ratio of 90:10. The trace element mineral raw materials are a combination of calcium source, magnesium source, zinc source, iron source, manganese source and copper source, wherein the mass ratio of available calcium, magnesium, zinc, iron, manganese and copper elements is 10:5:2:2:1:0.5. The calcium source is dolomite powder, the magnesium source is magnesite powder, the zinc source is zinc sulfate, the iron source is ferrous sulfate, the manganese source is manganese sulfate and the copper source is copper sulfate. The pH of the system is adjusted to 6.5 with citric acid or sodium hydroxide and water is added until the water content of the system is 55% to obtain the fermentation base material. (2) Primary mesophilic aerobic directional conversion fermentation: 70% of the total inoculum amount of the compound microbial fermentation agent is inoculated into the fermentation substrate (the total inoculum amount of the compound microbial fermentation agent is 0.5% of the total mass of the fermentation substrate). After thorough mixing, it is sent to the solid fermentation tank for primary aerobic fermentation. The fermentation temperature is controlled at 30-35℃, the fermentation time is 60h, and the pile is turned and aerated once every 12h to maintain the dissolved oxygen content of the system ≥5mg / L. (3) Secondary mesophilic micro-anaerobic in-situ chelation fermentation: After the primary fermentation is completed, the remaining 30% of the compound microbial fermentation agent is inoculated into the fermentation system, thoroughly mixed, and gently turned and aerated once every 24 hours to maintain the dissolved oxygen content of the system at 0.5-1 mg / L. The fermentation temperature is controlled at 32-37℃ and the fermentation time is 60 hours. (4) Three-stage low-temperature post-fermentation stabilization: After the two-stage chelation fermentation is completed, the pile temperature is maintained at 40-45℃ for post-fermentation for 60 hours. The pile is turned over once every 24 hours. When the pile temperature naturally drops to room temperature, the fermentation is completed. (5) Post-processing of the product: After fermentation, the material is spread out to room temperature, dried at a low temperature below 40°C, crushed, and passed through a 60-mesh sieve to obtain the biochemical humic acid chelated trace element fermentation product.

[0034] Step 3: Preparation of humic acid compound fertilizer (1) Weigh the above biochemical humic acid chelated micronutrient fermentation products, macronutrient fertilizers and auxiliary materials according to the weight ratio, crush them separately and pass them through an 80-mesh sieve for later use; (2) The sieved raw materials are fed into a twin-shaft paddle mixer and mixed thoroughly for 20 minutes to obtain a uniformly mixed base powder. (3) The base powder is fed into the rotary drum granulator, and saturated steam is introduced to adjust the moisture content and temperature of the material. The particle size of the formed particles is controlled at 2-4 mm. After granulation, the particles are cooled, dried and screened to obtain the humic acid compound fertilizer of this embodiment.

[0035] Example 3 This embodiment provides a humic acid compound fertilizer with the function of enhancing the efficacy of micronutrients, which is made from the following raw materials in parts by weight: 40 parts of biochemical humic acid chelated micronutrient fermentation product, 45 parts of macronutrient fertilizer, and 5 parts of auxiliary materials.

[0036] The main fertilizer is a compound of urea, monoammonium phosphate and potassium sulfate, with a mass ratio of 30:25:20; the auxiliary material is a mixture of attapulgite, zeolite powder and diatomaceous earth, with a mass ratio of 8:7:5.

[0037] Step 1: Preparation of compound microbial fermentation agent (1) Activation of strains: The freeze-dried bacterial powders of Bacillus belye, Ornithine aureus and Lactobacillus acidophilus were inoculated onto the corresponding slant culture medium and activated by constant temperature culture to obtain activated slant strains; Bacillus belye and Ornithine aureus were cultured on LB solid medium at 30-32℃ for 24h; Lactobacillus acidophilus was cultured on MRS solid medium at 35-38℃ for 24h. (2) Seed culture preparation: Each activated slant strain was inoculated into the corresponding liquid culture medium. Bacillus belye and Ornithine Bacillus aureus were cultured at 30-32℃ and 180r / min for 24h with shaking. Lactobacillus acidophilus was cultured at 35-38℃ with static anaerobic culture for 24h to obtain the seed culture of each strain. The effective viable count in each seed culture was ≥1 billion CFU / mL. (3) Preparation of compound microbial agent: The seed liquids of Bacillus belysae, Ornithine aureus and Lactobacillus acidophilus are mixed thoroughly in a volume ratio of 5:4:3 to obtain a compound seed liquid; the compound seed liquid is then inoculated into the sterilized solid fermentation medium at an inoculation rate of 10%, and solid fermented at a constant temperature of 30-35℃ for 48h. After fermentation, the mixture is dried and pulverized at a low temperature below 40℃ and passed through a 40-mesh sieve to obtain the compound microbial fermentation agent. The total effective viable count of the compound microbial agent is ≥20 billion CFU / g.

[0038] Step 2: Preparation of fermentation products containing trace elements in biochemical humic acid chelate form The product is prepared using a stepwise solid-state fermentation process, and the specific steps are as follows: (1) Raw material pretreatment: Agricultural waste mushroom residue is crushed to a particle size of 2-5 mm and mixed evenly with trace element mineral raw materials at a mass ratio of 80:20; the trace element mineral raw materials are a combination of calcium source, magnesium source, zinc source, iron source, manganese source and copper source, wherein the mass ratio of available calcium, magnesium, zinc, iron, manganese and copper elements is 20:15:5:5:3:1; the calcium source is calcium-based bentonite, the magnesium source is dolomite powder, the zinc source is zinc sulfate, the iron source is ferrous sulfate, the manganese source is manganese sulfate and the copper source is copper sulfate; the pH of the system is adjusted to 7.5 with citric acid or sodium hydroxide, and water is added until the water content of the system is 65% to obtain the fermentation base material; (2) Primary mesophilic aerobic directional conversion fermentation: 70% of the total inoculum amount of the compound microbial fermentation agent is inoculated into the fermentation substrate (the total inoculum amount of the compound microbial fermentation agent is 2.0% of the total mass of the fermentation substrate). After thorough mixing, it is sent to the solid fermentation tank for primary aerobic fermentation. The fermentation temperature is controlled at 30-35℃, the fermentation time is 72h, and the pile is turned and aerated once every 12h to maintain the dissolved oxygen content of the system ≥5mg / L. (3) Secondary mesophilic micro-anaerobic in-situ chelation fermentation: After the primary fermentation is completed, the remaining 30% of the compound microbial fermentation agent is inoculated into the fermentation system, thoroughly mixed, and gently turned and aerated once every 24 hours to maintain the dissolved oxygen content of the system at 0.5-1 mg / L. The fermentation temperature is controlled at 32-37℃ and the fermentation time is 72 hours. (4) Three-stage low-temperature post-fermentation stabilization: After the two-stage chelation fermentation is completed, the pile temperature is maintained at 40-45℃ for post-fermentation for 72 hours. The pile is turned over once every 24 hours. When the pile temperature naturally drops to room temperature, the fermentation is completed. (5) Post-processing of the product: After fermentation, the material is spread out to room temperature, dried at a low temperature below 40°C, crushed, and passed through a 60-mesh sieve to obtain the biochemical humic acid chelated trace element fermentation product.

[0039] Step 3: Preparation of humic acid compound fertilizer (1) Weigh the above biochemical humic acid chelated micronutrient fermentation products, macronutrient fertilizers and auxiliary materials according to the weight ratio, crush them separately and pass them through an 80-mesh sieve for later use; (2) The sieved raw materials are fed into a twin-shaft paddle mixer and mixed thoroughly for 30 minutes to obtain a uniformly mixed base powder. (3) The base powder is fed into the rotary drum granulator, and saturated steam is introduced to adjust the moisture content and temperature of the material. The particle size of the formed particles is controlled at 2-4 mm. After granulation, the particles are cooled, dried and screened to obtain the humic acid compound fertilizer of this embodiment.

[0040] Comparative Example 1 In this comparative example, except that *Bacillus belye* was not used in the preparation of the compound microbial fermentation agent, the raw materials and process steps were the same as in Example 1. That is: This comparative example provides a humic acid compound fertilizer with the function of enhancing the efficacy of micronutrients, which is made from the following raw materials in parts by weight: 30 parts of biochemical humic acid chelated micronutrient fermentation product, 55 parts of macronutrient fertilizer, and 10 parts of auxiliary materials.

[0041] Step 1: Preparation of compound microbial fermentation agent (1) Activation of strains: The freeze-dried bacterial powders of Ornithine Aureomyces and Lactobacillus acidophilus were inoculated onto the corresponding slant culture medium and activated by constant temperature culture to obtain activated slant strains; Ornithine Aureomyces was cultured on LB solid medium at 30-32℃ for 36h; Lactobacillus acidophilus was cultured on MRS solid medium at 35-38℃ for 36h. (2) Seed culture preparation: Each activated slant strain was inoculated into the corresponding liquid culture medium. Ornithine Bacillus aureus was cultured at 30-32℃ and 180r / min for 30h with shaking, and Lactobacillus acidophilus was cultured at 35-38℃ with static anaerobic culture for 30h to obtain the seed culture of each strain. The effective viable count in each seed culture was ≥1 billion CFU / mL. (3) Preparation of compound microbial agent: The seed liquids of each strain are thoroughly mixed at a volume ratio of 3:2 for *Ornithine Aureus* and *Lactobacillus acidophilus* to obtain a compound seed liquid; the compound seed liquid is then inoculated into a sterilized solid fermentation medium at an inoculation rate of 8%, and solid fermented at a constant temperature of 30-35℃ for 60h. After fermentation, the mixture is dried and pulverized at a low temperature below 40℃ and passed through a 40-mesh sieve to obtain the compound microbial fermentation agent. The total effective viable count of the compound microbial agent is ≥20 billion CFU / g.

[0042] Comparative Example 2 In this comparative example, except that *Ornithine aureus* is not used in the preparation of the compound microbial fermentation agent, the raw materials and process steps are the same as in Example 1. That is: This comparative example provides a humic acid compound fertilizer with the function of enhancing the efficacy of micronutrients, which is made from the following raw materials in parts by weight: 30 parts of biochemical humic acid chelated micronutrient fermentation product, 55 parts of macronutrient fertilizer, and 10 parts of auxiliary materials.

[0043] Step 1: Preparation of compound microbial fermentation agent (1) Activation of strains: The freeze-dried bacterial powders of Bacillus belye and Lactobacillus acidophilus were inoculated onto the corresponding slant culture medium and activated by constant temperature culture to obtain activated slant strains; Bacillus belye was cultured on LB solid medium at 30-32℃ for 36h; Lactobacillus acidophilus was cultured on MRS solid medium at 35-38℃ for 36h. (2) Seed culture preparation: Each activated slant strain was inoculated into the corresponding liquid culture medium. Bacillus berleis was cultured at 30-32℃ and 180r / min for 30h with shaking, and Lactobacillus acidophilus was cultured at 35-38℃ with static anaerobic culture for 30h to obtain the seed culture of each strain. The effective viable count in each seed culture was ≥1 billion CFU / mL. (3) Preparation of compound microbial agent: The seed liquids of Bacillus belysae and Lactobacillus acidophilus are mixed thoroughly at a volume ratio of 4:2 to obtain a compound seed liquid; the compound seed liquid is then inoculated into the sterilized solid fermentation medium at an inoculation rate of 8%, and solid fermented at a constant temperature of 30-35℃ for 60h. After fermentation, the mixture is dried and pulverized at a low temperature below 40℃ and passed through a 40-mesh sieve to obtain the compound microbial fermentation agent. The total effective viable count of the compound microbial agent is ≥20 billion CFU / g.

[0044] Comparative Example 3 In this comparative example, except that *Lactobacillus acidophilus* was not used in the preparation of the compound microbial fermentation agent, all other raw materials and process steps were the same as in Example 1. That is: This comparative example provides a humic acid compound fertilizer with the function of enhancing the efficacy of micronutrients, which is made from the following raw materials in parts by weight: 30 parts of biochemical humic acid chelated micronutrient fermentation product, 55 parts of macronutrient fertilizer, and 10 parts of auxiliary materials.

[0045] Step 1: Preparation of compound microbial fermentation agent (1) Activation of strains: The freeze-dried bacterial powders of Bacillus belye and Bacillus ornioides aureus were inoculated onto the corresponding slant culture medium and activated by constant temperature culture to obtain activated slant strains; Bacillus belye and Bacillus ornioides aureus were cultured on LB solid medium at 30-32℃ for 36h. (2) Seed culture preparation: Each activated slant strain was inoculated into the corresponding liquid culture medium. Bacillus belye and ornithine bacillus were cultured at 30-32℃ and 180r / min for 30h to obtain the seed culture of each strain. The effective viable count in each seed culture was ≥1 billion CFU / mL. (3) Preparation of compound microbial agent: The seed liquids of Bacillus belysae and Ornithine aureus are mixed thoroughly at a volume ratio of 4:3 to obtain a compound seed liquid; the compound seed liquid is then inoculated into the sterilized solid fermentation medium at an inoculation rate of 8%, and solid fermented at a constant temperature of 30-35℃ for 60h. After fermentation, the mixture is dried and pulverized at a low temperature below 40℃ and passed through a 40-mesh sieve to obtain the compound microbial fermentation agent. The total effective viable count of the compound microbial agent is ≥20 billion CFU / g.

[0046] Comparative Example 4 In this comparative example, except that Bacillus vesella in the compound microbial fermentation agent was replaced with other types of Bacillus, the other raw material ratios and process parameters were completely consistent with those in Example 1, that is: the strain used was Bacillus vesella with the number CGMCCNo.1.10901.

[0047] Comparative Example 5 In this comparative example, except that the *Ornithine glutamate* in the compound microbial fermentation agent was replaced with other types of glutamate bacteria, the other raw material ratios and process parameters were completely consistent with those in Example 1, namely: the strain used was *Mysore glutamate* with the number CGMCC No.1.8375.

[0048] Comparative Example 6 In this comparative example, except that the Lactobacillus acidophilus in the compound microbial fermentation agent was replaced with other types of Lactobacillus acidophilus, the other raw material ratios and process parameters were completely consistent with those in Example 1, that is, the strain used was Lactobacillus acidophilus with the number CGMCCNo.1.2919.

[0049] Comparative Example 7 This comparative example uses commercially available mineral-derived humic acid as a comparison. The only difference is that the biochemical humic acid chelated micronutrient fermentation product in Example 1 is replaced with an equal mass of mineral-derived humic acid + micronutrient mineral raw material physical mixture. All other raw material types, weight ratios, auxiliary material formulations, macronutrient fertilizer ratios, and production process steps are completely identical to Example 1. That is: This comparative humic acid compound fertilizer is made from the following raw materials in parts by weight: 30 parts mineral humic acid-micronutrient physical mixture, 55 parts macronutrient fertilizer, and 10 parts auxiliary materials.

[0050] Macronutrient fertilizer: It is completely consistent with Example 1, and is a compound combination of urea, monoammonium phosphate and potassium sulfate, with a mass ratio of 25:20:15. The auxiliary materials are exactly the same as those in Example 1, which are a mixture of attapulgite, zeolite powder and diatomaceous earth in a mass ratio of 6:5:3. Mineral-derived humic acid-trace element physical mixture: Mineral-derived humic acid (compliant with GB / T 33804-2017, total humic acid ≥50%, fulvic acid ≥10%), extracted from lignite, purchased from Shanghai Maclean Biochemical Technology Co., Ltd., was uniformly mixed with trace element mineral raw materials at a mass ratio of 85:15; wherein the composition of the trace element mineral raw materials and the mass ratio of available calcium, magnesium, zinc, iron, manganese, and copper elements were completely consistent with those in Example 1.

[0051] Except for the replacement of the core raw materials, all process steps and parameters are completely consistent with Example 1, as follows: 1. Weigh out the mineral-derived humic acid-trace element physical mixture, macro-element fertilizer, and auxiliary materials according to the weight ratio, crush them separately and pass them through an 80-mesh sieve, and set them aside; 2. Feed the sieved raw materials into a twin-shaft paddle mixer and mix thoroughly for 25 minutes to obtain a uniformly mixed base powder. 3. Feed the base powder into the rotary drum granulator, introduce saturated steam to adjust the moisture content and temperature of the material, and control the particle size of the formed particles to 2-4mm; after granulation, the particles are cooled, dried and screened to obtain this comparative proportion of humic acid compound fertilizer.

[0052] Test section: Antagonistic effect test of strains, test strains: Bacillus velezensis, strain number CGMCC No. 1.7417; Ornithinibacter aureus, strain number CGMCC No.1.10341; Lactobacillus acidophilus, strain number CGMCC No.1.1273.

[0053] The plating confrontation experiment was conducted on the three strains (Bacillus belyssae, Ornithine viridissioides, and Lactobacillus acidophilus) used in this invention using the streak plate method to verify their compatibility.

[0054] Preparation of the composite culture medium: A modified culture medium capable of simultaneously supporting the growth of three bacterial strains was prepared with the following formula (g / L): peptone 10g, beef extract 8g, yeast extract 5g, glucose 10g, Tween-80 1mL, dipotassium hydrogen phosphate 2g, sodium acetate 3g, triammonium citrate 1g, magnesium sulfate 0.2g, manganese sulfate 0.05g, agar 18g, pH 6.8. This medium combines the key nutrients of LB and MRS, meeting the basic growth requirements of aerobic and lactic acid bacteria. After sterilization at 121℃ for 20 min, the medium was poured into plates.

[0055] Inoculation and culture: On the same composite culture medium plate, the activated seed liquid of three strains (prepared according to the method in Example 1) was picked up with a sterile inoculation loop and intersected straight lines were drawn on the plate.

[0056] Place the plates in a sealed plastic bag or anaerobic gas-generating bag (if unavailable, wrap them tightly with plastic wrap) to create a microaerobic environment, which is conducive to the growth of Lactobacillus acidophilus. Incubate at 30℃ for 72 h. Observe whether there is a transparent inhibition zone or a clear growth inhibition band at the intersection of different colonies.

[0057] After 72 hours of incubation, clear colonies grew along all three streaks (e.g. Figure 1 (As shown in the figure). No transparent inhibition zone or growth inhibition band was observed at the intersection of any two colonies, and the colony boundaries showed a state of mutual fusion or staggered growth. This indicates that there is no antagonistic effect among Bacillus belyssus (Figure 1), Ornithine Aureobacterium (Figure 2), and Lactobacillus acidophilus (Figure 3), and they can be used in combination.

[0058] Performance testing: All test methods refer to current valid national and industry standards: The performance of the biochemical humic acid chelated trace element fermentation products prepared in the examples and comparative examples was tested: 1. Determination of total humic acid and fulvic acid content: Total humic acid content: NY / T 1971-2021 "Determination of humic acid content in water-soluble fertilizers" (after acid precipitation, measure the precipitate and solution separately, and sum to obtain total humic acid). Fulvic acid content: NY / T 3162-2022 "Determination of fulvic acid content in fertilizers" or the method in HG / T 5935-2021.

[0059] 2. Determination of total carboxyl and phenolic hydroxyl content: The determination was performed using an automatic potentiometric titrator, following the potentiometric titration method (refer to the relevant methods in HG / T 5935-2021 and GB / T34765-2017). The results are expressed as mmol / g.

[0060] 3. Determination of trace element content and chelation rate: Free and chelated elements were separated using the cation exchange resin method. (See method reference:) Disperse the fertilizer sample in deionized water until fully dissolved or suspended (adjust the pH to near neutral to avoid extreme pH that could damage the chelate structure). Separate free metal ions using a cation exchange resin column (the cation exchange resin adsorbs free M²⁺), while chelated elements pass directly through the resin column without participating in the ion exchange process. Collect the pass solution (chelated state) and the hydrochloric acid eluent (free state) separately, and determine the concentration of each target element in both fractions using ICP-OES or flame atomic absorption spectrophotometry (FAAS), and calculate the chelation rate. Calculate the chelation rate using the following formula: Chelation rate of each element (%) = [Mass of target element in chelated fraction / (Mass of target element in chelated fraction + Mass of target element in free fraction)] × 100% The arithmetic mean of the chelation rates of six elements—calcium, magnesium, zinc, iron, manganese, and copper—was taken as the average chelation rate of trace elements in the sample.

[0061] Fertilizer finished product performance testing: 1. Determination of effective viable bacteria count: The plate count method specified in GB 20287-2021 "Agricultural Microbial Agents" was used.

[0062] 2. Determination of physicochemical properties of compound fertilizer finished product: Total nutrients, moisture, pH value and particle size are determined according to the methods specified in GB / T 15063-2020 "Compound Fertilizer (Compound Fertilizer)".

[0063] 3. Determination of available trace element content in soil: Available zinc, manganese, iron, and copper were determined using the diethylenetriaminepentaacetic acid (DTPA) extraction method as specified in NY / T 890-2022 "Determination of available zinc, manganese, iron, and copper content in soil"; exchangeable calcium and magnesium were determined using the method specified in NY / T 1121.13-2023 "Soil testing - Part 13: Determination of exchangeable calcium and magnesium in soil".

[0064] 4. Pot Fertilizer Efficiency Test: The test crop was Zhengdan 958 maize. Each pot contained 15 kg of soil and 5 seeds were sown. After emergence, 2 seedlings were thinned to a maximum. Each treatment was replicated 6 times. Conventional field management was used. Maize was harvested at full maturity. Plant height, aboveground dry weight, root dry weight, and grain yield were measured. The total uptake of six elements (calcium, magnesium, zinc, iron, manganese, and copper) in maize plants (aboveground parts and roots) was measured separately. The utilization rate of each element was calculated using the following formula: Absorption and utilization rate (%) = (Element absorption by crops in the fertilized area - Element absorption by crops in the control area) / Element application rate in fertilizer × 100% The arithmetic mean of the utilization rates of the above six elements is taken as the "average absorption and utilization rate of micronutrients". The contents of calcium, magnesium, zinc, iron, manganese and copper in crop samples are digested and determined in accordance with NY / T 1972-2021 (or GB 5009.268).

[0065] Soil culture experiment design The tested soil was typical brown soil from the Stanley Linshu Agricultural Demonstration Park, with the following basic physicochemical properties: pH 6.8, organic matter 12.3 g / kg, available calcium 82.5 mg / kg, available magnesium 36.2 mg / kg, available zinc 1.2 mg / kg, available iron 5.8 mg / kg, available manganese 9.6 mg / kg, and available copper 1.0 mg / kg. A dosage of 20 kg of fertilizer per mu (approximately 0.067 hectares) was applied to the field. The corresponding amount of fertilizer was thoroughly mixed with air-dried soil that had passed through a 2 mm sieve, placed in plastic basins, and incubated at 25℃ in the dark for 28 days while maintaining 60% soil field capacity. After incubation, the content of available micronutrients in the soil was measured. A blank control group (CK) without fertilizer was also set up.

[0066] Table 1. Test results of core performance of biochemical humic acid chelated trace element fermentation products. The fermentation products of Examples 1-3 consistently showed a fulvic acid content of over 45% of the total humic acid, a total carboxyl + phenolic hydroxyl content ≥8.3 mmol / g, and an average chelation rate of trace elements ≥85%, all of which were significantly superior to those of the comparative examples. In Comparative Examples 1-3, the absence of a single strain resulted in a sharp decline in humic acid activation and chelation capacity. Even after replacing the strains in Comparative Examples 4-6 with other strains of the same genus, their performance remained far lower than the specific strain combination of this invention. This directly demonstrates that the ternary strain combination selected in this invention is not a conventional strain replacement in the field; the three strains work synergistically and are indispensable, forming the core innovative basis of this invention.

[0067] Table 2. Test results of physicochemical properties of finished humic acid compound fertilizer Table 3. Results of micronutrient content test in soil after 28 days of incubation Table 4 Results of fertilizer effect test in maize pots As can be seen from the data in Tables 2-4, the basic physicochemical indicators such as total nutrients, moisture, and particle size of the finished fertilizers from all examples and comparative examples meet the requirements of the national standard GB / T 15063-2020 and comply with quality standards. However, there are extremely significant differences in the improvement effect of soil available elements and fertilizer efficiency: Examples 1-3 show a significant increase in available micronutrients in the soil compared to the blank control group, with the average absorption and utilization rate of micronutrients in corn exceeding 56%. Plant height, dry matter accumulation, and grain yield all increased by more than 40% compared to the blank control group, and the various agronomic effects are far superior to all comparative examples. When any single strain is missing or replaced with other strains of the same genus, the improvement rate of available elements in the soil weakens, and the element absorption and utilization rate is less than 25%, with fertilizer efficiency far lower than that of the examples of this invention. Comparative example 7, which is prepared by direct physical mixing of unfermented mineral humic acid, shows that its indicators are only slightly higher than those of the blank control group, and it hardly reflects the activation and enhancement effect that humic acid should have. The test results fully demonstrate that the present invention uses a specific combination of ternary composite microbial strains to activate humic acid through synergistic fermentation and simultaneously chelate trace elements, which can significantly increase the proportion of fulvic acid and the content of active functional groups, obtain fermentation products with high chelation rate, and ultimately greatly improve the fertilizer efficiency and the utilization rate of trace elements. The technical effect is significantly better than the existing process.

[0068] It should be noted that the above embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

Claims

1. A humic acid compound fertilizer with the function of enhancing the efficacy of trace elements, characterized in that, It is made from the following raw materials in parts by weight: 20-40 parts of biochemical humic acid chelated micronutrient fermentation product, 45-65 parts of macronutrient fertilizer, and 5-15 parts of auxiliary materials; the biochemical humic acid chelated micronutrient fermentation product is obtained by mixing agricultural waste, micronutrient mineral raw materials, and a compound microbial fermentation agent, and then performing stepwise solid-state fermentation; the compound microbial fermentation agent is Bacillus belesiensis (…). Bacillus velezensis ), Ornithine Bacillus aureus ( Ornithinibacter aureus ) and Lactobacillus acidophilus ( Lactobacillus acidophilus )composition.

2. The humic acid compound fertilizer with micronutrient synergistic effect according to claim 1, characterized in that, The macro-element fertilizer is a compound combination of urea, monoammonium phosphate and potassium sulfate, with a mass ratio of (20-30):(15-25):(10-20).

3. The humic acid compound fertilizer with micronutrient synergistic effect according to claim 1, characterized in that, The auxiliary material is a mixture of attapulgite, zeolite powder and diatomaceous earth, with a mass ratio of (4-8):(3-7):(2-5).

4. The humic acid compound fertilizer with micronutrient synergistic effect according to claim 1, characterized in that, The compound microbial fermentation agent contains *Bacillus belyssima* strain number CGMCC No. 1.7417, purchased from the China General Microbiological Culture Collection Center; *Ornithine aureus* strain number CGMCC No. 1.10341, purchased from the China General Microbiological Culture Collection Center; and *Lactobacillus acidophilus* strain number CGMCC No. 1.12735, purchased from the China General Microbiological Culture Collection Center. The seed liquid volume ratio of *Bacillus belyssima*, *Ornithine aureus*, and *Lactobacillus acidophilus* in the compound microbial fermentation agent is (3-5):(2-4):(1-3), and the total effective viable count of the compound agent is ≥20 billion CFU / g. The preparation method of the compound microbial fermentation agent is as follows: (1) Activation of strains: The freeze-dried bacterial powders of Bacillus belye, Ornithine aureus, and Lactobacillus acidophilus were inoculated onto the corresponding slant culture media and activated by constant temperature culture to obtain activated slant strains; Bacillus belye and Ornithine aureus were cultured on LB solid medium at 30-32℃ for 24-48h; Lactobacillus acidophilus was cultured on MRS solid medium at 35-38℃ for 24-48h. (2) Seed culture preparation: Each activated slant strain was inoculated into the corresponding liquid culture medium. Bacillus belye and Ornithine Bacillus aureus were cultured at 30-32℃ and 180r / min for 24-36h with shaking. Lactobacillus acidophilus was cultured at 35-38℃ with static anaerobic culture for 24-36h to obtain the seed culture of each strain. The effective viable count in each seed culture was ≥1 billion CFU / mL. (3) Preparation of compound microbial agent: The seed liquids of Bacillus belyssus, Ornithine aureus and Lactobacillus acidophilus are mixed thoroughly according to the volume ratio of (3-5):(2-4):(1-3) to obtain a compound seed liquid. The compound seed liquid is then inoculated into the sterilized solid fermentation medium at an inoculation rate of 5%-10%. The mixture is fermented at a constant temperature of 30-35℃ for 48-72 hours. After the fermentation is completed, the mixture is dried and pulverized at a low temperature below 40℃ and passed through a 40-mesh sieve to obtain the compound microbial fermentation agent.

5. The humic acid compound fertilizer with micronutrient synergistic effect according to claim 4, characterized in that, Step (2) The liquid culture medium used for Bacillus belyssus and Ornithine aureus is LB liquid culture medium, and the liquid culture medium used for Lactobacillus acidophilus is MRS liquid culture medium; Step (3) The solid fermentation culture medium is composed of the following components by weight: 60-70 parts wheat bran, 15-25 parts corn flour, 8-15 parts soybean meal, 2-5 parts glucose, 0.1-0.3 parts magnesium sulfate, and 0.2-0.5 parts dipotassium hydrogen phosphate; When preparing the mixture, mix the raw materials according to the ratio, add deionized water to adjust the water content of the system to 45%-55%, adjust the pH value to 6.5-7.0, sterilize by high pressure steam at 121℃ for 30 minutes, and cool to room temperature for later use.

6. The humic acid compound fertilizer with micronutrient synergistic effect according to claim 1, characterized in that, The agricultural waste is mushroom residue, crushed to a particle size of 2-5 mm; the trace element mineral raw materials are a combination of calcium source, magnesium source, zinc source, iron source, manganese source and copper source, wherein the mass ratio of available calcium, magnesium, zinc, iron, manganese and copper elements is (10-20):(5-15):(2-5):(2-5):(1-3):(0.5-1).

7. The humic acid compound fertilizer with micronutrient synergistic effect according to claim 1, characterized in that, The stepwise solid-state fermentation preparation method of the biochemical humic acid chelated trace element fermentation product includes the following steps: (1) Raw material pretreatment: crush agricultural waste to a particle size of 2-5 mm, mix it evenly with trace element mineral raw materials according to the ratio, adjust the pH of the system to 6.5-7.5 with citric acid or sodium hydroxide, and add water to the system to a moisture content of 55%-65% to obtain fermentation base material; the mass ratio of agricultural waste to trace element mineral raw materials is (80-90):(10-20); (2) Primary mesophilic aerobic directional conversion fermentation: 70% of the total inoculum amount of the compound microbial fermentation agent is inoculated into the fermentation substrate, and after being thoroughly mixed, it is sent to the solid fermentation tank for primary aerobic fermentation. The fermentation temperature is controlled at 30-35℃, the fermentation time is 48-72h, and the pile is turned and aerated once every 12h to maintain the dissolved oxygen content of the system ≥5mg / L. (3) Secondary mesophilic micro-anaerobic in-situ chelation fermentation: After the primary fermentation is completed, the remaining 30% of the compound microbial fermentation agent is inoculated into the fermentation system, thoroughly mixed, and gently turned and aerated once every 24 hours to maintain the dissolved oxygen content of the system at 0.5-1 mg / L. The fermentation temperature is controlled at 32-37℃ and the fermentation time is 48-72 hours. (4) Three-stage low-temperature post-fermentation stabilization: After the two-stage chelation fermentation is completed, the pile temperature is maintained at 40-45℃ for post-fermentation for 48-72 hours. The pile is turned over once every 24 hours. When the pile temperature naturally drops to room temperature, the fermentation is completed. (5) Post-processing of the product: After fermentation, the material is spread out to room temperature, dried and crushed at a low temperature below 40°C, and passed through a 60-mesh sieve to obtain the biochemical humic acid chelated trace element fermentation product.

8. The humic acid compound fertilizer with micronutrient synergistic effect according to claim 7, characterized in that, The total inoculum amount of the compound microbial fermentation agent is 0.5%-2.0% of the total mass of the fermentation substrate.

9. A method for producing a humic acid compound fertilizer with micronutrient synergistic effects as described in any one of claims 1-8, characterized in that, Includes the following steps: (1) Preparation of biochemical humic acid chelated micronutrient fermentation products; (2) Weigh out the biochemical humic acid chelated micronutrient fermentation product, macronutrient fertilizer and auxiliary materials according to the weight ratio, crush them separately and pass them through an 80-mesh sieve, and set them aside. (3) Send the sieved raw materials into a twin-shaft paddle mixer and mix them thoroughly for ≥20 minutes to obtain a uniformly mixed base powder. (4) The base powder is fed into the rotary drum granulator, and saturated steam is introduced to adjust the moisture content and temperature of the material for wet granulation. The particle size of the formed particles is controlled at 2-4 mm. After granulation, the particles are cooled, dried and screened to obtain the humic acid compound fertilizer with the function of enhancing the effects of trace elements.

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