A composite microbial fertilizer based on cotton stalk fermentation liquor and ethyne salt mud and a preparation method thereof

Abstract

This invention relates to a compound microbial fertilizer based on cotton stalk fermentation broth and acetylene salt mud, and its preparation method. The method for preparing the compound microbial fertilizer based on cotton stalk fermentation broth and acetylene salt mud includes the following steps: Preparing pre-mixed material A: At 80-90℃, bentonite is added to cotton stalk fermentation broth 1, and after stirring and mixing evenly, acetylene salt mud phosphorus-iron extraction complex, trace elements, nitrogen fertilizer, and potassium humate are added sequentially to obtain pre-mixed material A; Preparing pre-mixed material B: At 80-90℃, phosphate fertilizer and potassium fertilizer are added sequentially to cotton stalk fermentation broth 2 to obtain pre-mixed material B; Pre-mixed material A and pre-mixed material B are mixed, and functional microbial agents are added, followed by granulation. The compound microbial fertilizer based on cotton stalk fermentation broth and acetylene salt mud described in this invention provides sufficient nutrients to the soil, meeting the requirements for farmland fertilization, while also exerting the effects of resisting pathogens and promoting growth, thus realizing the resource utilization of industrial and agricultural waste.

Description

Technical Field

[0001] This invention belongs to the field of compound microbial fertilizer technology, specifically relating to a compound microbial fertilizer based on cotton stalk fermentation liquid and acetylene salt mud and its preparation method. Background Technology

[0002] Traditional methods of burning or landfilling cotton stalks easily cause environmental pollution. Furthermore, cotton stalks are rich in cellulose (42-48%) and lignin (18-24%), resulting in a serious waste of biomass resources. In addition, acetylene sludge produced during acetylene production, as a large-scale industrial waste, mainly contains calcium hydroxide, phosphate, iron, magnesium, and trace heavy metals. Direct discharge of this sludge would cause a severe burden on soil and water bodies.

[0003] Although acetylene salt mud is rich in phosphorus and iron, which can theoretically serve as fertilizer nutrients and have high-value utilization potential, its practical application in fertilizer preparation faces significant technical obstacles: ① The inherent high pH and high salinity of acetylene salt mud can severely disrupt the chemical balance and physical stability of the fertilizer system, easily leading to the precipitation of trace elements, disintegration of the suspension system (significant decrease in suspension rate), and difficulty in granulation; ② If the trace heavy metal components it contains are not properly passivated and fixed, they can not only poison functional microorganisms, causing a sharp decline in viable bacteria count, but also pose a potential risk of soil pollution; ③ Its viscous physical properties make it difficult to mix evenly with agricultural waste fermentation liquid, posing a significant challenge to large-scale and stable production processes. Therefore, despite the industry's willingness to utilize resources, those skilled in the art still face significant technical difficulties and environmental risks in the practical application of acetylene salt mud for the preparation of high-quality compound microbial fertilizers, whether directly or through simple processing.

[0004] While existing microbial fertilizers can achieve partial recycling of agricultural resources, they generally suffer from numerous drawbacks. For example, Chinese Patent Publication No. CN216935735U (publication date: July 12, 2022, utility model name: a production device for water-soluble fertilizer from biogas slurry containing macro-elements) suffers from complex preparation processes and strong equipment dependence. Chinese Patent Publication No. CN118479941A (publication date: August 13, 2024, invention name: a processing method for bio-organic fertilizer and its bio-organic fertilizer) requires the addition of a large amount of special raw materials, resulting in high production costs and difficulty in large-scale promotion. Chinese Patent Publication No. CN118202931A (publication date: March 15, 2024, invention name: a method for improving and preparing nutrient soil using kitchen waste biogas residue) has low microbial activity in the product (live bacteria count < 100%). The existing technology has poor storage stability (CFU / g) and suffers from problems such as single nutrient elements and unsynergistic disease resistance and growth promotion effects. Furthermore, the biogas slurry (cotton stalk fermentation liquid) produced by anaerobic fermentation of cotton stalks is rich in organic matter, but direct application poses risks of nutrient imbalance and heavy metal accumulation. The existing technology fails to provide a complete solution that can effectively synergistically treat cotton stalk fermentation liquid and acetylene salt mud, while overcoming the above-mentioned technical obstacles, to produce a highly active, highly stable, and functionally synergistic compound microbial fertilizer. (Chinese Patent Publication No. CN118685302A (Publication Date: 2024.09.24, Invention Title: A Biocontrol Bacterium for Anthracnose in Strawberries, Inoculum Agent and Its Preparation Method and Application)

[0005] Therefore, developing a microbial compound fertilizer capable of simultaneously utilizing agricultural waste (cotton stalk fermentation liquid) and industrial waste (acetylene salt mud), effectively overcoming the series of technical challenges brought about by the introduction of acetylene salt mud, and ultimately obtaining a highly active, highly stable, and functionally synergistic microbial compound fertilizer, has become an urgent technical challenge in this field. Solving this problem is of great significance for promoting the development of a circular economy in industry and agriculture. In view of this, this invention proposes a new compound microbial fertilizer and its preparation method to address many shortcomings in existing technologies. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a compound microbial fertilizer based on cotton stalk fermentation liquid and acetylene salt mud. This preparation method is simple and uses cotton stalk fermentation liquid as the core raw material. Through chelation reaction, macro-elements, micro-elements, acetylene salt mud phosphorus-iron extraction complex and functional microbial agents are compounded to prepare a solid granular compound microbial fertilizer.

[0007] To achieve the above objectives, the technical solution adopted is as follows:

[0008] A method for preparing a compound microbial fertilizer based on cotton stalk fermentation broth and acetylene salt mud includes the following steps:

[0009] Preparation of pre-mixed material A: Bentonite is added to cotton stalk fermentation liquid 1 at 80-90℃. After stirring and mixing evenly, acetylene salt mud phosphorus iron extraction complex, trace elements, nitrogen fertilizer and potassium humate are added in sequence. Each component is mixed evenly before adding the next component to obtain pre-mixed material A.

[0010] Preparation of pre-mixed material B: At 80-90℃, add phosphate fertilizer and potassium fertilizer to cotton stalk fermentation liquid 2 in sequence. Mix each component evenly before adding the next component to obtain pre-mixed material B.

[0011] After mixing the pre-mixed material A and pre-mixed material B, functional microbial agents are added, and the mixture is granulated to obtain the compound microbial fertilizer.

[0012] Furthermore, the acetylene salt mud phosphorus-iron extraction complex is derived from the salt mud waste residue in the acetylene production process, and is obtained after acid extraction, impurity removal, precipitation, and drying. The specific preparation steps are as follows: the acetylene salt mud waste residue is crushed and passed through a 100-mesh sieve, and a 15% hydrochloric acid solution is added at a solid-liquid ratio of 1:5. The mixture is stirred at a constant temperature of 60°C for 2 hours for acid extraction. The insoluble residue is removed by filtration to obtain the acid extract. Sodium hydroxide solution is added to the acid extract to adjust the pH to 4.5-5.0, and the mixture is allowed to stand for 2 hours to precipitate. The filter cake is then filtered, washed with deionized water until the filtrate is neutral, and dried and crushed at 80°C to obtain the acetylene salt mud phosphorus-iron extraction complex.

[0013] Furthermore, the amounts of bentonite, acetylene salt mud phosphorus iron extraction complex, trace elements, nitrogen fertilizer, and potassium humate used in the cotton stalk fermentation liquid 1 are 8-10 wt%, 5-10 wt%, 20-33 wt%, 90-150 wt%, and 12-20 wt%, respectively.

[0014] The amounts of phosphate fertilizer and potassium fertilizer used are 35-55 wt% and 65-85 wt% of the cotton stalk fermentation liquid 2, respectively.

[0015] Furthermore, the trace elements include zinc sulfate, manganese sulfate, and boric acid, with dosages of 10-15 wt%, 6-10 wt%, and 4-8 wt% of the cotton stalk fermentation liquid 1, respectively.

[0016] Furthermore, the nitrogen fertilizer is UAN solution, the phosphate fertilizer is ammonium dihydrogen phosphate, and the potassium fertilizer is potassium sulfate.

[0017] Furthermore, the preparation of pre-mixed material A is as follows: Bentonite is added to cotton stalk fermentation liquid 1 at 80-90℃ and stirred for 2-3 hours. Then, acetylene salt mud phosphorus iron extraction complex is added and stirred for 0.5-1 hours. Trace elements and nitrogen fertilizer are added and stirred for 1-2 hours. Potassium humate is added and stirred for 2-4 hours. The mixture is then cooled to 70℃.

[0018] The preparation of pre-mixed material B is as follows: At 80-90℃, phosphate fertilizer is added to cotton stalk fermentation liquid 2 and stirred for 1-2 hours, then potassium fertilizer is added and stirred for 2-3 hours, and then cooled to 70℃.

[0019] Furthermore, the mass ratio of preform A to preform B is 1:0.8-1.2;

[0020] The amount of the functional microbial agent is 0.5-0.8 wt% of the total amount of preform A and preform B.

[0021] Furthermore, the mass ratio of preform A to preform B is 1:1;

[0022] The functional microbial agent is a compound of Trichoderma harzianum, Trichoderma echinospora and Bacillus thuringiensis powder in a mass ratio of 1:1:1, with each single strain having an effective viable count of ≥20 billion CFU / g.

[0023] Another objective of this invention is to provide a compound microbial fertilizer based on cotton stalk fermentation liquid and acetylene salt mud, prepared using the above-described preparation method, wherein a large number of elements ( The total amount should not be less than 300g / L, and the total number of viable bacteria should be greater than [amount missing]. cfu / mL.

[0024] Compared with the prior art, the beneficial effects of the present invention

[0025] This invention relates to the field of agricultural resource recycling and microbial fertilizer technology. Using cotton stalk fermentation liquid as the core raw material, a solid granular compound microbial fertilizer is prepared by chelation reaction to combine macro-elements, micro-elements, acetylene salt mud phosphorus-iron extraction complex, and functional microbial agents. It has the following advantages:

[0026] 1. Dual Enhancement of Stability and Activity: The acetylene salt mud phosphorus-iron extract complex, in synergy with potassium humate and bentonite, effectively adsorbs and passivates heavy metals while chelating trace elements, creating a protected microenvironment for functional microorganisms (Trichoderma harzianum, Trichoderma echinococcus, and Bacillus thuringiensis). Testing showed that the total viable count of functional microorganisms in the final product was not only not inhibited, but was actually more than 15% higher than the control sample without the acetylene salt mud phosphorus-iron extract complex. After 6 months of storage at room temperature, the viable count remained above 85%, demonstrating significantly enhanced storage stability.

[0027] 2. Significant Improvement in Physical Properties: The introduction of the acetylene salt mud phosphorus-iron extraction complex forms a complementary particle size distribution and suspension network with bentonite, unexpectedly improving the strength of the granulated particles and reducing their adhesion. Testing shows that the granule formation rate of the product of this invention is ≥95%, the particle strength is ≥8N, the disintegration time is ≤15min, and there is no adhesion or clumping. Its performance indicators far exceed those of conventional compound microbial fertilizers.

[0028] 3. Enhanced Synergistic Nutrition and Growth-Promoting / Disease-Resistant Effects: The iron, phosphorus, and other elements provided by acetylene salt mud are integrated into the potassium humate-bentonite composite system in a chelated state, making them easier for crops to absorb. Pot experiments on maize showed that, compared with fertilizers containing the same nutrients but without the acetylene salt mud phosphorus-iron extract complex, the application of the compound microbial fertilizer of this invention increased maize emergence rate by 8%, root vitality by 32%, plant height and fresh weight by 18% and 22% respectively, and achieved a control efficacy of over 75% against maize stem rot, demonstrating significant synergistic growth-promoting and disease-resistant effects.

[0029] 4. Co-resource utilization of industrial and agricultural waste: This invention realizes the high-value utilization of two major wastes, cotton stalk fermentation liquid and acetylene salt mud. The amount of cotton stalk fermentation liquid consumed reaches more than 40% of the total product mass. The acetylene salt mud phosphorus-iron extraction compound completely replaces conventional phosphate fertilizer and iron fertilizer raw materials, without generating secondary pollution, which meets the requirements of green circular economy development. The production cost is reduced by more than 15% compared with conventional compound microbial fertilizer. Detailed Implementation

[0030] To further illustrate the present invention's compound microbial fertilizer based on cotton stalk fermentation broth and acetylene salt mud, and its preparation method, and to achieve the intended purpose of the invention, the following detailed description, in conjunction with preferred embodiments, details the specific implementation methods, structures, features, and effects of the compound microbial fertilizer and its preparation method according to the present invention. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable manner.

[0031] The following will provide a more detailed description of the present invention, a compound microbial fertilizer based on cotton stalk fermentation broth and acetylene salt mud, and its preparation method, with reference to specific embodiments:

[0032] The technical solution of this invention comprises a chelation of cotton stalk fermentation broth, acetylene salt mud phosphorus iron extraction complex, bentonite, and trace elements, combined with macroelements and compounded with Trichoderma harzianum, Trichoderma echinococcus, and Bacillus thuringiensis, wherein:

[0033] (1) Product composition

[0034] Compound microbial fertilizer consists of the following components:

[0035] Carrier substrate: Cotton stalk fermentation broth (anaerobic fermentation biogas slurry of cotton stalks, cellulose degradation products, containing organic matter ≥85 g / L);

[0036] Industrial waste resource utilization components: Acetylene salt mud phosphorus iron extraction complex;

[0037] Chelating agents: bentonite, potassium humate;

[0038] Trace elements: zinc sulfate heptahydrate, manganese sulfate monohydrate, boric acid;

[0039] Macroelements: UAN solution (nitrogen source), ammonium dihydrogen phosphate (phosphorus source), potassium sulfate (potassium source);

[0040] Functional microorganisms: Trichoderma harzianum, Trichoderma echinosporum, and Bacillus thuringiensis powder (each single strain has an effective viable count of ≥20 billion CFU / g).

[0041] (2) Core indicators: macroelements ( Total amount ≥300 g / L, total number of viable functional microorganisms ≥ cfu / mL.

[0042] (3) Performance testing methods

[0043] ① Content of macronutrients: The content was determined in accordance with NY / T1107-2020 "Water-soluble fertilizers containing macronutrients";

[0044] ② Total viable count: determined according to GB20287-2006 "Agricultural Microbial Inoculants";

[0045] ③Heavy metal content: The content of heavy metals was determined in accordance with GB / T23349-2020 "Determination of Arsenic, Cadmium, Chromium, Lead and Mercury Content in Fertilizers";

[0046] ④ Particle performance: Particle strength, molding rate, and disintegration time were determined in accordance with GB / T15063-2020 "Compound Fertilizers";

[0047] ⑤ Fertilizer efficacy and disease resistance: These were determined through a corn pot experiment.

[0048] The technical solution adopted in this invention is as follows:

[0049] A method for preparing a compound microbial fertilizer based on cotton stalk fermentation broth and acetylene salt mud includes the following steps:

[0050] Preparation of pre-mixed material A: Bentonite is added to cotton stalk fermentation liquid 1 at 80-90℃. After stirring and mixing evenly, acetylene salt mud phosphorus iron extraction complex, trace elements, nitrogen fertilizer and potassium humate are added in sequence. Each component is mixed evenly before adding the next component to obtain pre-mixed material A.

[0051] Preparation of pre-mixed material B: At 80-90℃, add phosphate fertilizer and potassium fertilizer to cotton stalk fermentation liquid 2 in sequence. Mix each component evenly before adding the next component to obtain pre-mixed material B.

[0052] After mixing the pre-mixed material A and pre-mixed material B, functional microbial agents are added, and the mixture is granulated to obtain the compound microbial fertilizer.

[0053] In the above technical solution, potassium humate, instead of humic acid, is used as the core chelating agent and functional additive when preparing pre-mixed material A. This is for the cotton stalk fermentation liquid-acetylene salt mud system of the present invention. Potassium humate has the following irreplaceable advantages over humic acid:

[0054] (1) Better water solubility and system compatibility: Humic acid has extremely poor water solubility and can only dissolve in small amounts under strongly alkaline conditions. It is easy to precipitate and separate into layers in the cotton stalk fermentation liquid system, which will destroy the stability of the system. Potassium humate is the potassium salt of humic acid and has excellent water solubility. It can be completely dissolved in the reaction system at 80-90℃. It can be evenly mixed with cotton stalk fermentation liquid, bentonite, and acetylene salt mud phosphorus iron extraction complex to form a stable chelate system, avoiding the problems of trace element precipitation and system separation.

[0055] (2) Synergistic effect of nutrients: Potassium humate can provide additional readily available potassium elements, directly supplementing the potassium nutrients of fertilizers, and forming a synergistic effect of nitrogen, phosphorus and potassium with phosphorus fertilizers and nitrogen fertilizers in the system, helping to achieve the total amount of macro-elements; while humic acid can only provide organic matter, without additional nutrient supplementation, and cannot achieve synergistic effect of nutrients.

[0056] (3) Stronger pH buffering and heavy metal passivation capabilities: The acetylene salt mud phosphorus iron extraction complex in this system still has trace acidic residues. Potassium humate has a stronger pH buffering capacity, which can stabilize the pH of the system in the neutral range of 6.5-7.5. This not only avoids the toxicity of high pH to microorganisms, but also provides the optimal pH environment for heavy metal chelation and passivation. At the same time, potassium humate has more active functional groups such as carboxyl and hydroxyl groups. When combined with bentonite, the chelation and passivation efficiency of heavy metals such as lead, cadmium, and chromium is more than 20% higher than that of humic acid, which is more suitable for the heavy metal risk control needs of acetylene salt mud.

[0057] (4) Better microbial protection and growth promotion effect: Potassium humate can form a protective film on the surface of functional microorganisms, isolate the stress of salt and trace heavy metals in the system, and improve the storage stability of live bacteria; at the same time, it can be directly used as a carbon source for microorganisms, promoting the mycelial growth and spore germination of Trichoderma harzianum and Trichoderma echinosporum, and the effect of increasing the number of live bacteria is significantly better than that of humic acid; while humic acid is difficult for microorganisms to use directly and has no significant growth promotion effect.

[0058] (5) Optimization of granulation performance: Potassium humate has natural binding properties. When combined with bentonite, it can significantly improve the granulation rate and granulation strength, reduce the dust rate during the granulation process, and solve the problem of difficult granulation and easy disintegration of acetylene salt mud system. Humic acid has no binding properties and cannot improve granulation performance.

[0059] Preferably, the acetylene salt mud phosphorus-iron extraction complex is derived from salt mud waste residue in the acetylene production process, and is obtained after acid extraction, impurity removal, precipitation, and drying. The specific preparation steps are as follows: the acetylene salt mud waste residue is crushed and passed through a 100-mesh sieve, and a 15% hydrochloric acid solution is added at a solid-liquid ratio of 1:5. The mixture is stirred at a constant temperature of 60°C for 2 hours for acid extraction. The insoluble residue is removed by filtration to obtain the acid extract. Sodium hydroxide solution is added to the acid extract to adjust the pH to 4.5-5.0, and the mixture is allowed to stand for 2 hours to precipitate. The filter cake is then filtered, washed with deionized water until the filtrate is neutral, and dried and crushed at 80°C to obtain the acetylene salt mud phosphorus-iron extraction complex.

[0060] Composition analysis revealed that the acetylene salt mud phosphorus-iron extract complex contained ≥28% phosphorus pentoxide, ≥12% total iron, <0.5% calcium hydroxide, and ≤10mg / kg total heavy metals (lead, cadmium, chromium, mercury, and arsenic). It exhibited no high alkali or high salt risk and met the safety standards for fertilizer raw materials.

[0061] Preferably, the amounts of bentonite, acetylene salt mud phosphorus-iron extract complex, trace elements, nitrogen fertilizer, and potassium humate are 8-10 wt%, 5-10 wt%, 20-33 wt%, 90-150 wt%, and 12-20 wt% of cotton stalk fermentation liquid 1, respectively.

[0062] The amounts of phosphate fertilizer and potassium fertilizer used are 35-55 wt% and 65-85 wt% of the cotton stalk fermentation liquid 2, respectively.

[0063] More preferably, the trace elements include zinc sulfate, manganese sulfate, and boric acid, with dosages of 10-15 wt%, 6-10 wt%, and 4-8 wt% of the cotton stalk fermentation liquid 1, respectively.

[0064] Preferably, the nitrogen fertilizer is UAN solution, the phosphate fertilizer is ammonium dihydrogen phosphate, and the potassium fertilizer is potassium sulfate.

[0065] Preferably, the preparation of pre-mixed material A is as follows: Bentonite is added to cotton stalk fermentation liquid 1 at 80-90℃ and stirred for 2-3 hours. Then, acetylene salt mud phosphorus iron extraction complex is added and stirred for 0.5-1 hours. Then, trace elements and nitrogen fertilizer are added and stirred for 1-2 hours. Then, potassium humate is added and stirred for 2-4 hours. Finally, the mixture is cooled to 70℃.

[0066] The preparation of pre-mixed material B is as follows: At 80-90℃, phosphate fertilizer is added to cotton stalk fermentation liquid 2 and stirred for 1-2 hours, then potassium fertilizer is added and stirred for 2-3 hours, and then cooled to 70℃.

[0067] Preferably, the mass ratio of preform A to preform B is 1:0.8-1.2;

[0068] The amount of the functional microbial agent is 0.5-0.8 wt% of the total amount of preform A and preform B.

[0069] More preferably, the mass ratio of preform A to preform B is 1:1;

[0070] The functional microbial agent is a compound of Trichoderma harzianum, Trichoderma echinospora and Bacillus thuringiensis powder in a mass ratio of 1:1:1.

[0071] Preferably, a disc granulator is used for granulation (particle size range 2-4 mm), and the mixture is dried at 60-70℃ until the moisture content is ≤8% to obtain solid granular compound microbial fertilizer.

[0072] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0073] In this embodiment, the acetylene salt mud phosphorus-iron extraction complex is derived from salt mud waste residue in the acetylene production process. It is obtained through acid extraction, impurity removal, precipitation, and drying. The specific preparation steps are as follows: The acetylene salt mud waste residue is pulverized and passed through a 100-mesh sieve. A 15% hydrochloric acid solution is added at a solid-liquid ratio of 1:5, and the mixture is stirred at 60°C for 2 hours for acid extraction. Insoluble residues are removed by filtration to obtain the acid extract. Sodium hydroxide solution is added to the acid extract to adjust the pH to 4.5-5.0, and the mixture is allowed to stand for 2 hours to precipitate. The filter cake is then collected, washed with deionized water until the filtrate is neutral, and dried and pulverized at 80°C to obtain the acetylene salt mud phosphorus-iron extraction complex.

[0074] Example 1.

[0075] The specific steps are as follows:

[0076] (1) Pre-made material A: Take 1 ton of cotton stalk fermentation liquid, add 80 kg of bentonite (8 wt%), stir at 85℃ for 2.5 h; add 50 kg of acetylene salt mud phosphorus iron extraction complex (5 wt%), continue to keep warm and stir for 0.5 h; add in sequence: 100 kg of zinc sulfate heptahydrate (10 wt%), 80 kg of manganese sulfate monohydrate (8 wt%), 60 kg of boric acid (6 wt%), 900 kg of UAN solution (90 wt%), keep warm and stir for 1.5 h, add 150 kg of potassium humate (15 wt%), continue to keep warm and stir for 3 h, and cool down to 70℃.

[0077] (2) Pre-made material B: Take another 1 ton of cotton stalk fermentation liquid, add 400 kg (40 wt%) of ammonium dihydrogen phosphate, stir at 88℃ for 1.5 h, add 750 kg (75 wt%) of potassium sulfate, keep warm and stir for 2 h, and cool down to 70℃.

[0078] (3) Compound granulation: Mix pre-mixed materials A and B at a mass ratio of 1:1, add compound bacterial powder (Trichoderma harzianum: Trichoderma echinosporum: Bacillus thuringiensis mass ratio 1:1:1, total addition amount 0.75wt%), form into shape using a disc granulator (particle size 2-4mm), and dry at 60℃ until moisture content ≤8%.

[0079] Performance test results: Total macro-elements 326 g / L, total viable bacteria 3.6 × 10⁻⁶ g / L The particle size distribution is cfu / mL, particle strength is 8.2N, molding rate is 96.2%, and total heavy metal content meets the requirements of GB38400-2019 "Limits of Toxic and Hazardous Substances in Fertilizers".

[0080] Example 2.

[0081] The specific steps are as follows:

[0082] (1) Pre-made material A: Take 1 ton of cotton stalk fermentation liquid, add 100 kg of bentonite (10 wt%), stir at 85℃ for 2.5 h; add 100 kg of acetylene salt mud phosphorus iron extraction complex (10 wt%), continue to keep warm and stir for 1 h; add in sequence: 150 kg of zinc sulfate heptahydrate (15 wt%), 100 kg of manganese sulfate monohydrate (10 wt%), 80 kg of boric acid (8 wt%), 1500 kg of UAN solution (150 wt%), keep warm and stir for 1.5 h, add 200 kg of potassium humate (20 wt%), continue to keep warm and stir for 3 h, and cool down to 70℃.

[0083] (2) Pre-made material B: Take another 1 ton of cotton stalk fermentation liquid, add 550 kg (55 wt%) of ammonium dihydrogen phosphate, stir at 88℃ for 1.5 h, add 850 kg (85 wt%) of potassium sulfate, keep warm and stir for 2 h, and cool down to 70℃.

[0084] (3) Compound granulation: Mix pre-mixed materials A and B at a mass ratio of 1:1, add compound bacterial powder (Trichoderma harzianum: Trichoderma echinosporum: Bacillus thuringiensis mass ratio 1:1:1, total addition amount 0.8wt%), form into shape using a disc granulator (particle size 2-4mm), and dry at 60℃ until moisture content ≤8%.

[0085] Performance test results: Total macro-elements 412 g / L, total viable bacteria 3.8 × 10⁻⁶ g / L cfu / mL, particle strength 8.7N, molding rate 95.8%, and total heavy metal content meets GB38400-2019 standard.

[0086] Example 3.

[0087] The specific steps are as follows:

[0088] (1) Pre-made material A: Take 1 ton of cotton stalk fermentation liquid, add 90 kg of bentonite (9 wt%), stir at 85℃ for 2.5 h; add 80 kg of acetylene salt mud phosphorus iron extraction complex (8 wt%), continue to keep warm and stir for 0.8 h; add in sequence: 130 kg of zinc sulfate heptahydrate (13 wt%), 80 kg of manganese sulfate monohydrate (8 wt%), 60 kg of boric acid (6 wt%), 1200 kg of UAN solution (120 wt%), keep warm and stir for 1.5 h, add 160 kg of potassium humate (16 wt%), continue to keep warm and stir for 3 h, and cool down to 70℃.

[0089] (2) Pre-made material B: Take another 1 ton of cotton stalk fermentation liquid, add 450 kg (45 wt%) of ammonium dihydrogen phosphate, stir at 88℃ for 1.5 h, add 750 kg (75 wt%) of potassium sulfate, keep warm and stir for 2 h, and cool down to 70℃.

[0090] (3) Compound granulation: Mix pre-mixed materials A and B at a mass ratio of 1:1, add compound bacterial powder (Trichoderma harzianum: Trichoderma echinosporum: Bacillus thuringiensis mass ratio 1:1:1, total addition amount 0.7wt%), form into shape using a disc granulator (particle size 2-4mm), and dry at 60℃ until the moisture content is ≤8%.

[0091] Performance test results: Total macro-elements 368 g / L, total viable bacteria 3.9 × 10⁻⁶ g / L cfu / mL, particle strength 8.5N, molding rate 96.5%, and total heavy metal content meets GB38400-2019 standard.

[0092] Example 4.

[0093] The specific steps are as follows:

[0094] (1) Pre-made material A: Take 1 ton of cotton stalk fermentation liquid, add 85 kg of bentonite (8.5 wt%), stir at 85℃ for 2.5 h; add 70 kg of acetylene salt mud phosphorus iron extraction complex (7 wt%), continue to keep warm and stir for 0.7 h; add in sequence: 120 kg of zinc sulfate heptahydrate (12 wt%), 70 kg of manganese sulfate monohydrate (7 wt%), 50 kg of boric acid (5 wt%), 1100 kg of UAN solution (110 wt%), keep warm and stir for 1.5 h, add 140 kg of potassium humate (14 wt%), continue to keep warm and stir for 3 h, and cool down to 70℃.

[0095] (2) Pre-made material B: Take another 1 ton of cotton stalk fermentation liquid, add 400 kg (40 wt%) of ammonium dihydrogen phosphate, stir at 88℃ for 1.5 h, add 700 kg (70 wt%) of potassium sulfate, keep warm and stir for 2 h, and cool down to 70℃.

[0096] (3) Compound granulation: Mix pre-mixed materials A and B at a mass ratio of 1:1, add compound bacterial powder (Trichoderma harzianum: Trichoderma echinosporum: Bacillus thuringiensis mass ratio 1:1:1, total addition amount 0.8wt%), form into shape using a disc granulator (particle size 2-4mm), and dry at 60℃ until moisture content ≤8%.

[0097] Performance test results: Total macro-elements 345 g / L, total viable bacteria 3.7 × 10⁻⁶ g / L cfu / mL, particle strength 8.3N, molding rate 96.0%, and total heavy metal content meets GB38400-2019 standard.

[0098] Example 5.

[0099] The specific steps are as follows:

[0100] (1) Pre-made material A: Take 1 ton of cotton stalk fermentation liquid, add 95 kg of bentonite (9.5 wt%), stir at 85℃ for 2.5 h; add 90 kg of acetylene salt mud phosphorus iron extraction complex (9 wt%), continue to keep warm and stir for 1 h; add in sequence: 140 kg of zinc sulfate heptahydrate (14 wt%), 90 kg of manganese sulfate monohydrate (9 wt%), 70 kg of boric acid (7 wt%), 1300 kg of UAN solution (130 wt%), keep warm and stir for 1.5 h, add 180 kg of potassium humate (18 wt%), continue to keep warm and stir for 3 h, and cool down to 70℃.

[0101] (2) Pre-made material B: Take another 1 ton of cotton stalk fermentation liquid, add 500 kg (50 wt%) of ammonium dihydrogen phosphate, stir at 88℃ for 1.5 h, add 800 kg (80 wt%) of potassium sulfate, keep warm and stir for 2 h, and cool down to 70℃.

[0102] (3) Compound granulation: Mix pre-mixed materials A and B at a mass ratio of 1:1, add compound bacterial powder (Trichoderma harzianum: Trichoderma echinosporum: Bacillus thuringiensis mass ratio 1:1:1, total addition amount 0.75wt%), form into shape using a disc granulator (particle size 2-4mm), and dry at 60℃ until moisture content ≤8%.

[0103] Performance test results: Total macro-elements 387 g / L, total viable bacteria 4.1 × 10⁻⁶ g / L cfu / mL, particle strength 8.6N, molding rate 96.3%, and total heavy metal content meets GB38400-2019 standard.

[0104] Example 6.

[0105] The specific steps are as follows:

[0106] (1) Pre-made material A: Take 1 ton of cotton stalk fermentation liquid, add 80 kg of bentonite (8 wt%), stir at 90℃ for 2 h; add 50 kg of acetylene salt mud phosphorus iron extraction complex (5 wt%), continue to keep warm and stir for 0.5 h; add in sequence: 100 kg of zinc sulfate heptahydrate (10 wt%), 60 kg of manganese sulfate monohydrate (6 wt%), 40 kg of boric acid (4 wt%), 900 kg of UAN solution (90 wt%), keep warm and stir for 1 h, add 120 kg of potassium humate (12 wt%), continue to keep warm and stir for 2 h, and cool down to 70℃.

[0107] (2) Pre-made material B: Take another 1 ton of cotton stalk fermentation liquid, add 350 kg (35 wt%) of ammonium dihydrogen phosphate, stir at 90°C for 1 h, add 650 kg (65 wt%) of potassium sulfate, keep warm and stir for 2.5 h, and cool down to 70°C.

[0108] (3) Compound granulation: Mix pre-mixed materials A and B at a mass ratio of 1:0.8, add compound bacterial powder (Trichoderma harzianum: Trichoderma echinosporum: Bacillus thuringiensis mass ratio 1:1:1, total addition amount 0.5wt%), form into shape using a disc granulator (particle size 2-4mm), and dry at 60℃ until moisture content ≤8%.

[0109] Performance test results: Total macro-elements 308 g / L, total viable bacteria 2.8 × 10⁻⁶ g / L cfu / mL, particle strength 8.0N, molding rate 95.5%, and total heavy metal content meets GB38400-2019 standard.

[0110] Example 7.

[0111] The specific steps are as follows:

[0112] (1) Pre-made material A: Take 1 ton of cotton stalk fermentation liquid, add 90 kg of bentonite (9 wt%), stir at 80℃ for 3 h; add 70 kg of acetylene salt mud phosphorus iron extraction complex (7 wt%), continue to keep warm and stir for 1 h; add in sequence: 120 kg of zinc sulfate heptahydrate (12 wt%), 80 kg of manganese sulfate monohydrate (8 wt%), 50 kg of boric acid (5 wt%), 1000 kg of UAN solution (100 wt%), keep warm and stir for 2 h, add 140 kg of potassium humate (14 wt%), continue to keep warm and stir for 4 h, and cool down to 70℃.

[0113] (2) Pre-made material B: Take another 1 ton of cotton stalk fermentation liquid, add 450 kg (45 wt%) of ammonium dihydrogen phosphate, stir at 80°C for 2 hours, add 700 kg (70 wt%) of potassium sulfate, keep warm and stir for 3 hours, and cool down to 70°C.

[0114] (3) Compound granulation: Mix pre-mixed materials A and B at a mass ratio of 1:1.2, add compound bacterial powder (Trichoderma harzianum: Trichoderma echinosporum: Bacillus thuringiensis mass ratio 1:1:1, total addition amount 0.6wt%), form into shape using a disc granulator (particle size 2-4mm), and dry at 60℃ until moisture content ≤8%.

[0115] Performance test results: Total macro-elements 332 g / L, total viable bacteria 3.2 × 10⁻⁶ g / L cfu / mL, particle strength 8.1N, molding rate 95.7%, and total heavy metal content meets GB38400-2019 standard.

[0116] Example 8: Experimental Test

[0117] Multiple sets of comparative experiments were set up to verify the effectiveness of the technical solution of the present invention. All experiments were repeated in triplicate, and the average value was taken.

[0118] (1) Experiment 1: Component verification of the acetylene salt mud phosphorus iron extraction complex

[0119] Test methods: X-ray fluorescence spectrometry (XRF) was used to determine the composition of the acetylene salt mud phosphorus iron extraction complex and the original acetylene salt mud waste used in the examples. The calcium hydroxide content was determined by titration and the heavy metal content was determined by atomic absorption spectrophotometry.

[0120] The experimental results are shown in Table 1.

[0121] Table 1

[0122]

[0123] Conclusion: The acid extraction-precipitation process of this invention completely removes the high content of calcium hydroxide in acetylene salt mud, achieves efficient enrichment of phosphorus and iron elements, and significantly reduces the content of heavy metals. It solves the technical problem of high alkalinity and high heavy metal content in acetylene salt mud from the source, laying a safe foundation for subsequent fertilizer preparation.

[0124] (2) Experiment 2: Verification of the passivation effect of heavy metals

[0125] Test method: Seven treatment groups were set up. Each group was supplemented with a mixed standard solution of lead, cadmium, and chromium of the same concentration, according to the corresponding components in Table 2. The solid-liquid ratio was 1:10. The solution was incubated at 25℃ with shaking for 2 hours, then allowed to stand for 24 hours. The supernatant was filtered, and the concentration of heavy metal ions in the solution was measured to calculate the heavy metal passivation rate. Specifically:

[0126] Seven treatment groups were established. Each group used 1000 mL of deionized water as a solvent and added a mixed standard solution of lead, cadmium, and chromium of the same concentration (the initial concentration of lead, cadmium, and chromium was 50 mg / L). The corresponding components were added according to Table 2, with a solid-liquid ratio of 1:10. The solutions were shaken at 25 °C for 2 h, allowed to stand for 24 h, filtered, and the supernatant was collected. The concentration of heavy metal ions in the solution was determined by atomic absorption spectrophotometry, and the passivation rate of heavy metals was calculated.

[0127] The only changes in T1-T7 are the acetylene salt mud phosphorus iron extraction complex, potassium humate, and bentonite; the remaining components are the same as in Example 1. Furthermore, the amounts of each component in T1-T7 are completely consistent with the formulation ratios in Example 1 of this invention. The components and amounts of the seven treatment groups are clearly defined as follows:

[0128] -T1: Only 0.5g of acetylene salt mud phosphorus iron extraction complex was added, without potassium humate or bentonite.

[0129] -T2: Only 1.5g of potassium humate was added; no acetylene salt mud phosphorus iron extract complex or bentonite was added.

[0130] -T3: Only 0.8g of bentonite was added; no acetylene salt mud phosphorus iron extract complex or potassium humate were added.

[0131] -T4: Add 0.5g of acetylene salt mud phosphorus iron extraction complex + 1.5g of potassium humate, without bentonite.

[0132] -T5: Add 0.5g of acetylene salt mud phosphorus iron extraction complex + 0.8g of bentonite, without potassium humate.

[0133] -T6: Add 1.5g potassium humate + 0.8g bentonite, acetylene-free salt mud phosphorus iron extraction complex.

[0134] -T7: Add 0.5g of acetylene salt mud phosphorus iron extraction complex + 1.5g of potassium humate + 0.8g of bentonite (the system of this invention).

[0135] The experimental results are shown in Table 2.

[0136] Table 2. Heavy metal passivation effects of different treatment groups

[0137]

[0138] Conclusion: The ternary synergistic system of this invention achieves a passivation rate of over 90% for heavy metals, which is far higher than that of single components and binary combinations. It realizes efficient passivation and fixation of heavy metals, completely solves the risk of heavy metal pollution in acetylene salt mud, and provides a non-toxic living environment for functional microorganisms.

[0139] (3) Experiment 3: Validation of microbial activity and storage stability

[0140] Test method: Four treatment groups were set up. The basic formula and preparation process of all treatment groups were the same as those in Example 1, with only the core components adjusted as follows:

[0141] -CK group: Without the addition of acetylene salt mud phosphorus iron extract complex, potassium humate, and bentonite, the rest of the formulation is the same as in Example 1.

[0142] Group D1: Original acetylene salt mud was added to replace the acetylene salt mud phosphorus-iron extraction complex; the rest of the formulation was the same as in Example 1.

[0143] Group D2: Only acetylene salt mud phosphorus iron extraction complex was added; potassium humate and bentonite were not added. The rest of the formulation was the same as in Example 1.

[0144] -D3 group (this invention): Contains acetylene salt mud phosphorus iron extraction complex + potassium humate + bentonite, i.e., the product of Example 1 of this invention.

[0145] All four groups were prepared using the same process. The initial total number of viable bacteria after preparation and the total number of viable bacteria after 6 months of sealed storage at room temperature were measured, and the viable bacteria retention rate was calculated.

[0146] The experimental results are shown in Table 3.

[0147] Table 3. Changes in microbial activity in different treatment groups

[0148]

[0149] Conclusion: Raw acetylene salt mud severely poisons functional microorganisms, leading to a sharp decline in viable cell count. The treatment group with only the addition of the acetylene salt mud phosphorus-iron extraction complex, without the addition of potassium humate and bentonite, had significantly lower initial viable cell count and storage retention rate than the system of this invention. However, the acetylene salt mud phosphorus-iron extraction complex of this invention, in synergy with potassium humate and bentonite, not only did not inhibit microbial activity, but also increased the initial viable cell count by 16.1% compared to the control group, and increased the viable cell retention rate by 18.4% after 6 months of storage. This fully demonstrates the synergistic effect of the three, perfectly solving the problem of acetylene salt mud's toxicity to microorganisms and achieving a dual improvement in microbial activity and storage stability.

[0150] (4) Experiment 4: Verification of particle physical properties

[0151] Test method: Four treatment groups were set up: CK group: no addition of acetylene salt mud phosphorus-iron extract complex and bentonite, the rest of the formula was the same as in Example 1; T1 group: compared with CK group, bentonite was added; T2 group: compared with CK group, acetylene salt mud phosphorus-iron extract complex was added; T3 group: the product of Example 1 of this invention. The particle formation rate, particle strength, and disintegration time of each group were measured.

[0152] The experimental results are shown in Table 4.

[0153] Table 4. Particle physical properties of different treatment groups

[0154]

[0155] Conclusion: The acetylene salt mud phosphorus iron extraction complex of the present invention, in synergy with bentonite, forms a complementary particle size distribution, increasing the particle forming rate to over 95%, the particle strength to over 8N, and the disintegration time to less than 15 minutes, perfectly solving the technical problems of difficult granulation, easy adhesion, and slow disintegration of the acetylene salt mud system.

[0156] (5) Experiment 5: Verification of fertilizer effect and disease resistance in potted plants

[0157] Test Method: Using maize as the test crop, three treatment groups were set up, with three replicates per group and 10 seeds sown per pot. CK group: applied with conventional compound fertilizer of equal nutrient content (excluding acetylene salt mud and functional microorganisms); T1 group: applied with compound microbial fertilizer of equal nutrient content and microbial content (excluding acetylene salt mud phosphorus-iron extract complex); T2 group: applied with the product of Example 1 of this invention. The fertilization rate was consistent, and normal field management was implemented. Maize emergence rate, 30-day plant height, fresh weight, root activity, and control efficacy against maize stem rot were measured.

[0158] The experimental results are shown in Table 5.

[0159] Table 5. Indicators of maize growth and disease resistance in different treatment groups

[0160]

[0161] Conclusion: Compared with conventional compound fertilizers and microbial fertilizers without acetylene salt mud, the compound microbial fertilizer of the present invention has significantly improved seedling emergence rate, growth indicators, root vitality and disease resistance, achieving the technical effect of "1+1>2" of synergistic nutrition and growth promotion and disease resistance, and meeting the actual application needs of farmland fertilization.

[0162] As can be seen from the embodiments, the technical solution of the present invention realizes the synergistic resource utilization of agricultural waste cotton stalks and industrial waste acetylene salt mud, and the prepared compound microbial fertilizer has a total macro-element content ≥300g / L and a total viable bacteria count >2× With a concentration of cfu / mL, it can provide sufficient nutrients to the soil, while also having disease-resistant and growth-promoting effects. It also solves industry problems such as high salt and alkali content, heavy metal risks, and microbial activity inhibition in acetylene-containing mud. It is suitable for large-scale fertilization in farmland and has good circular economy value and industrial application prospects.

[0163] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A preparation method of a composite microbial fertilizer based on cotton stalk fermentation liquor and acetylene salt mud, characterized in that, The preparation method comprises the following steps: Preparation of pre-preparation A: at 80-90℃, bentonite is added into cotton stalk fermentation liquor 1, after stirring and mixing uniformly, acetylene salt mud phosphorus iron extraction complex, trace elements, nitrogen fertilizer, humic acid potassium are added in turn, after mixing each component, the next component is added, and pre-preparation A is obtained; Preparation of pre-preparation B: at 80-90℃, phosphorus fertilizer and potassium fertilizer are added into cotton stalk fermentation liquor 2 in turn, after mixing each component, the next component is added, and pre-preparation B is obtained; The pre-preparation A and the pre-preparation B are mixed, and then functional microbial agent is added, granulation is carried out, and the composite microbial fertilizer is obtained.

2. The preparation method according to claim 1, wherein the acetylene salt mud phosphorus iron extraction complex is obtained from salt mud waste residues in the acetylene production process after acid extraction, impurity removal, precipitation and drying treatment.

3. The preparation method according to claim 1, wherein the amount of bentonite, acetylene salt mud phosphorus iron extraction complex, trace elements, nitrogen fertilizer and humic acid potassium is 8-10wt%, 5-10wt%, 20-33wt%, 90-150wt% and 12-20wt% of cotton stalk fermentation liquor 1 respectively; and the amount of phosphorus fertilizer and potassium fertilizer is 35-55wt% and 65-85wt% of cotton stalk fermentation liquor 2 respectively.

4. The preparation method according to claim 3, wherein the trace elements include zinc sulfate, manganese sulfate and boric acid, and the amount is 10-15wt%, 6-10wt% and 4-8wt% of cotton stalk fermentation liquor 1 respectively.

5. The preparation method according to claim 1, wherein the nitrogen fertilizer is UAN solution, the phosphorus fertilizer is ammonium dihydrogen phosphate, and the potassium fertilizer is potassium sulfate.

6. The preparation method according to claim 1, wherein the preparation of pre-preparation A: at 80-90℃, bentonite is added into cotton stalk fermentation liquor 1, stirring for 2-3h, then acetylene salt mud phosphorus iron extraction complex is added and stirred for 0.5-1h, then trace elements and nitrogen fertilizer are added and stirred for 1-2h, then humic acid potassium is added and stirred for 2-4h, and then cooled to 70℃; The preparation of pre-preparation B: at 80-90℃, phosphorus fertilizer is added into cotton stalk fermentation liquor 2 and stirred for 1-2h, then potassium fertilizer is added and stirred for 2-3h, and then cooled to 70℃.

7. The preparation method according to claim 1, wherein the mass ratio of pre-preparation A and pre-preparation B is 1:0.8-1.2; The amount of functional microbial agent is 0.5-0.8wt% of the total amount of pre-preparation A and pre-preparation B.

8. The preparation method according to claim 7, wherein the mass ratio of pre-preparation A and pre-preparation B is 1:1; The functional microbial agent is a compound of Trichoderma harzianum, Trichoderma asperellum and Bacillus thuringiensis powder with a mass ratio of 1:1:1, and the effective viable bacterial count of each single bacterium is ≥200 billion cfu / g. The composite microbial fertilizer is prepared by the preparation method in any one of claims 1-8.

10. The composite microbial fertilizer according to claim 9, wherein ​ ​ ​ ​ ​ 9. A composite microbial fertilizer based on cotton stalk fermentation liquor and acetylene salt mud, characterized in that, ​ ​ The total amount of the macroelements in the composite microbial fertilizer is ≥ 300 g / L, and the total number of viable functional microorganisms is ≥ 10 cfu / g.

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