Microbial fertilizer for improving soil and preparation method thereof

Abstract

The invention discloses a microbial fertilizer for improving soil and a preparation method of the microbial fertilizer. The microbial fertilizer is prepared from the following raw materials in parts by weight: 35 to 45 parts of modified charcoal, 15 to 25 parts of complex microbial inoculant, 3 to 7 parts of chitosan, 2 to 5 parts of carboxymethyl cellulose, 10 to 15 parts of bentonite, 5 to 10 parts of oxygen producer, 3 to 8 parts of dolomite powder, 3 to 8 parts of nano silicon dioxide and 10 to 25 parts of deionized water. The multi-stage pores of the modified biochar and the iron and manganese oxide can adsorb pollutants, meanwhile, a good breeding microenvironment is provided for microorganisms, and the oxygen producer promotes the activity of aerobic bacteria. Chitosan and carboxymethyl cellulose are used as adhesives, and bentonite and dolomite powder are used for adjusting pH and providing mineral substances.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of microbial fertilizer, and particularly relates to a microbial fertilizer for improving soil and a preparation method thereof. BACKGROUND

[0002] Microbial fertilizer, also known as biological fertilizer, is a preparation containing specific active microorganisms, which is applied to agricultural production, aiming to improve the nutritional conditions of crops, improve the soil structure, prevent diseases and ultimately improve the yield and quality of crops through the life activities of microorganisms. Compared with traditional chemical fertilizers, microbial fertilizers have the advantages of lower production cost, environmental friendliness and the ability to activate inherent nutrient resources in the soil. The action mechanism is complex and diverse, including fixing nitrogen in the atmosphere through symbiotic or autotrophic nitrogen-fixing bacteria, activating soil-fixed phosphorus and potassium elements through phosphorus and potassium solubilizing bacteria, promoting crop growth through the secretion of plant hormones, and inhibiting the growth of soil-borne pathogenic bacteria through the production of antibiotics and other substances.

[0003] However, in recent years, with the increase of agricultural intensification, the excessive use of chemical fertilizers has led to a series of serious environmental problems, such as soil compaction, decrease of organic matter content, acidification or salinization, and water eutrophication. These problems seriously restrict the sustainable development of agriculture. Under this background, it is particularly important to develop efficient and environmentally friendly microbial fertilizers.

[0004] Existing microbial fertilizer products, although showing good effects in improving soil and providing nutrients, are mostly passive and static in their action mode. After the fertilizer is applied to the soil, the activity and functional exertion rate of the beneficial microorganisms are mainly subject to the overall environmental conditions of the soil, such as temperature, humidity and pH value. This “one-size-fits-all” supply mode often cannot accurately match the dynamic and differentiated needs of crops for nutrients and microbial assistance at different growth stages (such as seedling stage, flowering stage and grain filling stage), resulting in waste of microbial activity and limiting the full exertion of the fertilizer efficacy. Therefore, developing a new type of microbial fertilizer that can “sense” the real-time needs of crops and make “intelligent” responses to realize “on-demand supply” of nutrients and microbial activity is the key to solving the above technical problems. SUMMARY

[0005] The first object of the present application is to provide a microbial fertilizer for improving soil, so as to solve the technical problems of single function and inability to dynamically match the needs of crops in the prior art.

[0006] The second object of the present application is to provide a preparation method of the above microbial fertilizer.

[0007] To achieve the above objectives, the first aspect of the present invention provides a soil-improving microbial fertilizer comprising the following raw materials in parts by weight: 35-45 parts modified biochar, 15-25 parts compound microbial agent, 3-7 parts chitosan, 2-5 parts carboxymethyl cellulose, 10-15 parts bentonite, 5-10 parts oxygenating agent, 3-8 parts dolomite powder, 3-8 parts nano silica, and 10-25 parts deionized water.

[0008] Optionally, the preparation method of the modified biochar includes the following steps: S1 Raw material pretreatment: Coconut shells and waste mushroom sticks are mixed at a mass ratio of 7:3 and pulverized to 80-100 mesh, soaked in 5% citric acid solution for 10-12 hours to remove ash, and dried until the moisture content is <5%; S2 Oxygen-limited pyrolysis: Under nitrogen protection, the temperature is increased to 380-400℃ at 10℃ / min and held for 1-3 hours, then increased to 600-650℃ at 5℃ / min and held for 30-60 minutes to form pyrolytic carbon with multi-level pores; S3 Chemical modification of iron and manganese loading: The pyrolytic carbon is immersed in a mixture of 0.5 mol / L ferric nitrate solution and 0.3 mol / L potassium permanganate solution, and ultrasonically assisted to promote the entry of iron and manganese ions into the pores. After drying at 115-120℃, it is calcined at 350-380℃ for 2-3 hours to generate stable iron tetroxide / manganese dioxide composite oxide; S4 Post-activation treatment: 800℃ superheated steam is introduced for 15-30 minutes to increase the specific surface area to 800-1000 m² / g; after soaking in Aspergillus niger fermentation broth for 24 hours, it is quickly dried to form modified biochar with a biomimetic nanofiber structure on the surface.

[0009] Optionally, the volume ratio of the ferric nitrate solution to the potassium permanganate solution is 2:1.

[0010] Optionally, in step S3, the ultrasound-assisted treatment conditions are 40 kHz and 60 °C for 1.5-2.5 h.

[0011] Optionally, the concentration of the Aspergillus niger fermentation broth in step S4 is 8-12 g / L.

[0012] Optionally, the compound microbial agent is a mixture of nitrogen-fixing bacteria, effective microbial flora (EM bacteria), and arbuscular mycorrhizal fungi in a mass ratio of (1-3):(2-5):(5-8).

[0013] Optionally, the content of the nitrogen-fixing bacteria is not less than cfu / g, wherein the effective microbial community content is not less than cfu / g, the arbuscular mycorrhizal fungi are not less than cfu / g.

[0014] Optionally, the oxygenating agent is a compound of magnesium peroxide, sodium percarbonate and vermiculite in a mass ratio of 1-3:2:1.3.

[0015] Optionally, the nano-silica has an average particle size of 20-50 nm and a specific surface area of ​​≥200 m² / g.

[0016] Optionally, according to any of the preceding microbial fertilizers, the microbial fertilizer further includes 1-5 parts by weight of intelligent responsive microcapsules; the intelligent responsive microcapsules encapsulate a microbial activity enhancer and are configured to accelerate the release of the microbial activity enhancer in response to changes in the physicochemical parameters of the rhizosphere microenvironment caused by crop root exudates.

[0017] Optionally, the smart responsive microcapsule has a core-shell structure, and its shell material includes a pH-sensitive polymer and / or an enzymatically hydrolyzable polymer.

[0018] Optionally, the pH-sensitive polymer is selected from at least one of polylactic acid, polyglycolic acid, polylactic-co-glycolic acid copolymer, and polycaprolactone; the enzymatically hydrolyzable polymer is selected from at least one of chitosan, sodium alginate, and cellulose derivatives.

[0019] Optionally, the microbial activity enhancer includes amino acids, yeast extracts, and flavonoids for inducing the expression of specific functional genes in microorganisms.

[0020] Optionally, the change in the physicochemical parameters of the rhizosphere microenvironment is a decrease in the pH value of the rhizosphere microregion; when the pH value of the shell material of the smart responsive microcapsule is lower than a preset release threshold, its hydrolysis or degradation rate increases nonlinearly.

[0021] The second aspect of the present invention provides a method for preparing soil-improving microbial fertilizer, comprising the following steps: weighing the raw materials in the specified weight proportions, and mixing modified biochar, compound microbial agent, chitosan, carboxymethyl cellulose, bentonite, oxygenating agent, dolomite powder, nano silica and deionized water to obtain microbial fertilizer.

[0022] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention obtains a composite carrier with multi-level pores, high iron and manganese oxide loading and biomimetic nanofiber structure through a special modified biochar preparation process. It can not only efficiently adsorb heavy metals and organic pollutants in soil, but also provide a superior colonization and reproduction site for microbial agents. At the same time, the biomimetic structure can enhance the attachment and activity of microorganisms.

[0023] 2. This invention constructs a stable and efficient microenvironment for microbial action by scientifically compounding multiple functional components, such as slow-release oxygenating agents, pH adjusters, and binders, thereby synergistically enhancing the multiple effects of microbial fertilizers, including soil improvement, nutrient activation, and pollution remediation.

[0024] 3. This invention introduces an intelligent response microcapsule module. This module can "recognize" chemical "distress signals" emitted by crops through root exudates during specific stress or growth stages, and respond by releasing targeted activity enhancers. This design transforms microbial fertilizer from a passive nutrient supply unit into an intelligent system capable of interacting with plants, achieving dynamic and precise matching between fertilizer activity release and real-time crop needs, greatly improving fertilizer utilization efficiency and the accuracy of its effects. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] Unless otherwise specified, the raw materials used in this invention are all from commercially available conventional products.

[0027] Preparation Example 1 This preparation example provides a method for preparing modified biochar, specifically including the following steps: S1 Raw Material Pretreatment: Mix 70g of dried coconut shells with 30g of waste mushroom sticks (rich in natural extracellular polymers), pulverize using a high-speed grinder, and pass through an 80-mesh sieve to ensure uniform particle size. Place the pulverized material in a 1L beaker, add 500mL of a 5% (w / v) citric acid aqueous solution, and magnetically stir and soak for 10 hours at room temperature. The purpose of this step is to utilize the complexing effect of citric acid to effectively remove ash formed by alkali metal and alkaline earth metal ions such as potassium, sodium, and calcium contained in the raw material, thereby improving the porosity and purity of the biochar during subsequent pyrolysis. After soaking, filter the material, wash repeatedly with deionized water until the filtrate is neutral, and then dry in an oven at 105℃ for 8 hours until its moisture content is below 5%.

[0028] S2 Oxygen-Limited Pyrolysis: The pretreated, dried raw material is placed in a tube furnace and subjected to programmed temperature pyrolysis under a nitrogen atmosphere (nitrogen flow rate of 200 mL / min). First, the temperature is increased from room temperature to 380°C at a rate of 10°C / min and held at this temperature for 1 hour. During this stage, hemicellulose and some cellulose decompose, forming the initial microporous structure. Subsequently, the temperature is increased to 600°C at a slower rate of 5°C / min and held at this temperature for 30 minutes. This high-temperature stage primarily promotes the deep carbonization and aromatization of lignin, further expanding and developing the pores through gas escape, forming pyrolytic char with a multi-level pore structure of micropores and mesopores. After the program is completed, the material is naturally cooled to room temperature under nitrogen protection.

[0029] S3 Chemically Modified Iron-Manganese Support: Take 50g of the pyrolytic carbon prepared above and immerse it in 600mL of a pre-prepared mixed solution. The mixed solution consists of 400mL of 0.5mol / L... The solution and 200 mL of 0.3 mol / L solution The solution is a mixture, in which and The volume ratio was 2:1. The suspension was placed in an ultrasonic cleaner with a power of 250W and a frequency of 40kHz, and subjected to ultrasonic-assisted treatment for 1.5 hours in a 60℃ water bath. The cavitation effect of ultrasound can break the surface tension of the liquid, generating a powerful microjets, thereby forcibly removing the surface tension. and Ions are driven and transported deep into the micropores of the pyrolytic carbon. After treatment, the ion-loaded pyrolytic carbon is recovered by filtration and dried at 115°C for 4 hours. The dried sample is then placed in a muffle furnace and calcined at 350°C for 2 hours in air. During this process, Decomposes to produce iron oxide. It decomposes and reacts with carbon, ultimately generating highly dispersed and structurally stable biochar in situ on the surface and within the pores. Composite oxide nanoparticles.

[0030] S4 Post-Activation Treatment: The biochar loaded with iron and manganese oxides was placed back into a tube furnace. When the furnace temperature reached 800°C, superheated steam generated by a steam generator (flow rate of 1.0 g / min) was introduced into the furnace for physical activation treatment for 15 minutes. High-temperature steam, as a mild oxidant, can selectively etch the amorphous carbon on the surface of the biochar. This process unclogs blocked pores, creates new micropores, and significantly increases the specific surface area. After activation, steam supply is stopped, and the mixture is allowed to cool to room temperature under nitrogen protection. At this point, the specific surface area of ​​the modified biochar (BET method) is measured to have increased to 800. Finally, the activated biochar was immersed in an 8 g / L Aspergillus niger fermentation broth for 24 hours to allow its surface to fully adsorb extracellular polysaccharides and other substances from the fermentation broth. Then, it was dried using rapid freeze-drying technology. During the drying process, these extracellular polysaccharides self-assembled, forming a biomimetic nanofiber network structure on the biochar surface. This structure significantly increases the attachment sites for microorganisms and effectively protects them from environmental stresses.

[0031] Preparation Example 2 This preparation example provides a method for preparing modified biochar, which differs from Preparation Example 1 in that: In step S1, coconut shells and waste mushroom sticks are mixed and crushed to 100 mesh, and soaked in citric acid solution for 12 hours.

[0032] In step S2, the temperature is raised to 390°C in the first stage and held for 2 hours, and then raised to 630°C in the second stage and held for 45 minutes.

[0033] In step S3, the ultrasonic-assisted treatment time is 2 hours, the drying temperature is 120℃, and the calcination temperature is 360℃.

[0034] In step S4, the superheated steam treatment time is 25 minutes, ultimately increasing the specific surface area to 900. The concentration of Aspergillus niger fermentation broth was 10 g / L.

[0035] Preparation Example 3 This preparation example provides a method for preparing modified biochar, which differs from Preparation Example 1 in that: In step S1, coconut shells and waste mushroom sticks are mixed and crushed to 100 mesh, and soaked in citric acid solution for 12 hours.

[0036] In step S2, the first stage involves heating to 400°C and holding for 3 hours, while the second stage involves heating to 650°C and holding for 60 minutes.

[0037] In step S3, the ultrasonic-assisted treatment time is 2.5 hours, the drying temperature is 120℃, and the calcination temperature is 380℃.

[0038] In step S4, the superheated steam treatment time is 30 minutes, ultimately increasing the specific surface area to 1000. The concentration of Aspergillus niger fermentation broth was 12 g / L.

[0039] Preparation Example 4: Preparation of pH-Sensitive Smart Response Microcapsules This preparation example provides a method for preparing smart responsive microcapsules that can respond to changes in the pH of the rhizosphere microenvironment. The specific steps are as follows: S210 Core Material Preparation: A microbial activity enhancer solution was prepared. Exemplarily, 0.5 g of L-glutamic acid (as a highly efficient nitrogen source and signaling molecule), 1.0 g of yeast extract (providing abundant vitamins and growth factors), and 10 mg of kaempferol (a flavonoid compound that can act as a signaling molecule to induce the expression of the rhizobium nodulin gene) were dissolved in 100 mL of deionized water. The solution was stirred thoroughly until clear and transparent, serving as the core material for microcapsules.

[0040] S220 Capsule Wall Material Preparation: This step uses a pH-sensitive biodegradable polymer. For example, 2.0 g of polylactic-co-glycolic acid copolymer (PLGA, where the molar ratio of lactic acid to glycolic acid is 75:25, and the weight-average molecular weight is 50 kDa) is weighed and completely dissolved in 20 mL of dichloromethane to form a homogeneous, transparent oil phase solution, which serves as the capsule wall material. This ratio of PLGA is chosen to ensure slow degradation in near-neutral soil environments, while significantly accelerating ester bond hydrolysis under acidic conditions (pH < 6.0).

[0041] S230 Microcapsule Emulsification and Solidification: A W / O / W type double emulsion-solvent evaporation method was employed. First, 10 mL of the core aqueous solution prepared in step S210 was added to 20 mL of the PLGA oil phase solution prepared in step S220. The mixture was sheared at 10,000 rpm for 2 minutes using a high-speed homogenizer to form a primary emulsion (W / O type). Subsequently, this primary emulsion was rapidly injected into 200 mL of an aqueous solution containing 2% (w / v) polyvinyl alcohol (PVA), and emulsification was continued at 500 rpm for 5 minutes to form a W / O / W type double emulsion. This double emulsion system was transferred to a large beaker and stirred continuously at room temperature for 24 hours to allow the dichloromethane solvent in the oil phase to slowly evaporate. As the solvent evaporated, the dissolved PLGA gradually deposited and solidified on the surface of the aqueous core droplets, forming microcapsules with a distinct core-shell structure.

[0042] S240 Microcapsule Post-processing: The suspension containing the solidified microcapsules was centrifuged at 8000 rpm for 10 minutes, and the supernatant was discarded. The precipitated microcapsules were subjected to three cycles of centrifugation and washing with deionized water to remove residual PVA and unencapsulated active substances. Finally, the washed microcapsules were freeze-dried for 48 hours to obtain a free-flowing white or pale yellow microcapsule powder with an average particle size of approximately 100 μm as measured by a laser particle size analyzer. The encapsulation efficiency of the activity enhancer reached over 85%.

[0043] Example 1 This embodiment provides a method for preparing soil-improving microbial fertilizer, including the following steps: Accurately weigh 35g of the modified biochar prepared in Example 1, 15g of the compound microbial agent, 3g of chitosan powder, 2g of sodium carboxymethyl cellulose, 10g of bentonite, 5g of oxygenating agent, 3g of dolomite powder, 3g of nano-silica, and 10g of deionized water. Place all the above powdered raw materials in a mixer and dry mix for 5 minutes to ensure that the components are macroscopically uniform. Then, slowly add 10g of deionized water dropwise while stirring, and continue wet mixing for 15 minutes to form loose clumps with uniform moisture content. Finally, granulate the mixture into granular microbial fertilizer with a particle size of 2-4mm using an extrusion granulator.

[0044] The compound microbial agent is a mixture of nitrogen-fixing bacteria, EM bacteria, and arbuscular mycorrhizal fungi in a mass ratio of 1:2:5, with a nitrogen-fixing bacteria content of 1.5 × 10⁻⁶. 8 cfu / g, EM bacteria content 5.5×10 8 cfu / g, arbuscular mycorrhizal fungi 5×10 6 cfu / g.

[0045] The oxygenating agent is a compound of magnesium peroxide, sodium percarbonate and vermiculite in a mass ratio of 1:2:1.3.

[0046] The average particle size of the nano-silica is 20 nm.

[0047] Example 2 A method for preparing soil-improving microbial fertilizer includes the following steps: weighing 40g of modified biochar, 20g of compound microbial agent, 5g of chitosan, 3g of carboxymethyl cellulose, 12g of bentonite, 8g of oxygenating agent, 5g of dolomite powder, 5g of nano silica, and 15g of deionized water from Preparation Example 2 and mixing them to obtain microbial fertilizer.

[0048] The compound microbial agent is a mixture of nitrogen-fixing bacteria, EM bacteria, and arbuscular mycorrhizal fungi in a mass ratio of 1:3:8, with a nitrogen-fixing bacteria content of 1.5 × 10⁻⁶. 8 cfu / g, EM bacteria content 5.5×10 8 cfu / g, arbuscular mycorrhizal fungi 5×10 6 cfu / g.

[0049] The oxygenating agent is a compound of magnesium peroxide, sodium percarbonate and vermiculite in a mass ratio of 2:2:1.3.

[0050] The average particle size of the nano-silica is 35 nm.

[0051] Example 3 A method for preparing soil-improving microbial fertilizer includes the following steps: weighing 45g of modified biochar, 25g of compound microbial agent, 7g of chitosan, 5g of carboxymethyl cellulose, 15g of bentonite, 10g of oxygenating agent, 8g of dolomite powder, 5g of nano-silica, and 25g of deionized water from Preparation Example 3 and mixing them to obtain microbial fertilizer.

[0052] The compound microbial agent is a mixture of nitrogen-fixing bacteria, EM bacteria, and arbuscular mycorrhizal fungi in a mass ratio of 3:5:8, with a nitrogen-fixing bacteria content of 1.5 × 10⁻⁶. 8 cfu / g, EM bacteria content 5.5×10 8 cfu / g, arbuscular mycorrhizal fungi 5×10 6 cfu / g.

[0053] The oxygenating agent is a compound of magnesium peroxide, sodium percarbonate and vermiculite in a mass ratio of 3:2:1.3.

[0054] The average particle size of the nano-silica is 50 nm.

[0055] Example 4 A method for preparing soil-improving microbial fertilizer includes the following steps: weighing 35g of modified biochar, 15g of compound microbial agent, 3g of chitosan, 2g of carboxymethyl cellulose, 10g of bentonite, 5g of oxygenating agent, 3g of dolomite powder, 3g of nano silica, and 10g of deionized water from Preparation Example 2 and mixing them to obtain microbial fertilizer.

[0056] The compound microbial agent is a mixture of nitrogen-fixing bacteria, EM bacteria, and arbuscular mycorrhizal fungi in a mass ratio of 2:2:5, with a nitrogen-fixing bacteria content of 2.5 × 10⁻⁶. 8 cfu / g, EM bacteria content 6.5×10 8 cfu / g, arbuscular mycorrhizal fungi 5.5×10 6 cfu / g.

[0057] The oxygenating agent is a compound of magnesium peroxide, sodium percarbonate, and vermiculite in a mass ratio of 1:2:1.3. The average particle size of the nano-silica is 20 nm.

[0058] Example 5 A method for preparing soil-improving microbial fertilizer includes the following steps: weighing 35g of modified biochar, 15g of compound microbial agent, 3g of chitosan, 2g of carboxymethyl cellulose, 10g of bentonite, 5g of oxygenating agent, 3g of dolomite powder, 3g of nano silica, and 10g of deionized water from Preparation Example 3 and mixing them to obtain microbial fertilizer.

[0059] The compound microbial agent is a mixture of nitrogen-fixing bacteria, EM bacteria, and arbuscular mycorrhizal fungi in a mass ratio of 3:2:6, with a nitrogen-fixing bacteria content of 3×10⁻⁶. 8cfu / g, EM bacteria content 6×10 8 cfu / g, arbuscular mycorrhizal fungi 6×10 6 cfu / g.

[0060] The oxygenating agent is a compound of magnesium peroxide, sodium percarbonate and vermiculite in a mass ratio of 2:2:1.3.

[0061] The average particle size of the nano-silica is 20 nm.

[0062] Example 6 A method for preparing soil-improving microbial fertilizer includes the following steps: weighing 40g of modified biochar, 20g of compound microbial agent, 5g of chitosan, 3g of carboxymethyl cellulose, 12g of bentonite, 8g of oxygenating agent, 5g of dolomite powder, 5g of nano silica and 15g of deionized water from Preparation Example 1 and mixing them to obtain microbial fertilizer.

[0063] The compound microbial agent is a mixture of nitrogen-fixing bacteria, EM bacteria, and arbuscular mycorrhizal fungi in a mass ratio of 2:3:8, with a nitrogen-fixing bacteria content of 3×10⁻⁶. 8 cfu / g, EM bacteria content 5×10 8 cfu / g, arbuscular mycorrhizal fungi 5×10 6 cfu / g.

[0064] The oxygenating agent is a compound of magnesium peroxide, sodium percarbonate and vermiculite in a mass ratio of 2:2:1.3.

[0065] The average particle size of the nano-silica is 35 nm.

[0066] Example 7 A method for preparing soil-improving microbial fertilizer includes the following steps: weighing 40g of modified biochar, 20g of compound microbial agent, 5g of chitosan, 3g of carboxymethyl cellulose, 12g of bentonite, 8g of oxygenating agent, 5g of dolomite powder, 5g of nano silica, and 15g of deionized water from Preparation Example 3 and mixing them to obtain microbial fertilizer.

[0067] The compound microbial agent is a mixture of nitrogen-fixing bacteria, EM bacteria, and arbuscular mycorrhizal fungi in a mass ratio of 1:5:8, with a nitrogen-fixing bacteria content of 2.5 × 10⁻⁶. 8 cfu / g, EM bacteria content 5.5×10 8 cfu / g, arbuscular mycorrhizal fungi 6×10 6 cfu / g.

[0068] The oxygenating agent is a compound of magnesium peroxide, sodium percarbonate and vermiculite in a mass ratio of 2:2:1.3.

[0069] The average particle size of the nano-silica is 35 nm.

[0070] Example 8 A method for preparing soil-improving microbial fertilizer includes the following steps: weighing 45g of modified biochar, 25g of compound microbial agent, 7g of chitosan, 5g of carboxymethyl cellulose, 15g of bentonite, 10g of oxygenating agent, 8g of dolomite powder, 5g of nano-silica, and 25g of deionized water from Preparation Example 1 and mixing them to obtain microbial fertilizer.

[0071] The compound microbial agent is a mixture of nitrogen-fixing bacteria, EM bacteria, and arbuscular mycorrhizal fungi in a mass ratio of 3:2:6, with a nitrogen-fixing bacteria content of 3.5 × 10⁻⁶. 8 cfu / g, EM bacteria content 6×10 8 CFU / g, arbuscular mycorrhizal fungi 6.5 × 10⁻⁶ 6 cfu / g.

[0072] The oxygenating agent is a compound of magnesium peroxide, sodium percarbonate and vermiculite in a mass ratio of 3:2:1.3.

[0073] The average particle size of the nano-silica is 50 nm.

[0074] Example 9 A method for preparing soil-improving microbial fertilizer includes the following steps: weighing 45g of modified biochar, 25g of compound microbial agent, 7g of chitosan, 5g of carboxymethyl cellulose, 15g of bentonite, 10g of oxygenating agent, 8g of dolomite powder, 5g of nano-silica, and 25g of deionized water from Preparation Example 2 and mixing them to obtain microbial fertilizer.

[0075] The compound microbial agent is a mixture of nitrogen-fixing bacteria, EM bacteria, and arbuscular mycorrhizal fungi in a mass ratio of 2:5:8, with a nitrogen-fixing bacteria content of 2.5 × 10⁻⁶. 8 cfu / g, EM bacteria content 6.5×10 8 cfu / g, arbuscular mycorrhizal fungi 5×10 6 cfu / g.

[0076] The oxygenating agent is a compound of magnesium peroxide, sodium percarbonate and vermiculite in a mass ratio of 3:2:1.3.

[0077] The average particle size of the nano-silica is 50 nm.

[0078] Example 10 (Preferred Example) This embodiment provides an intelligent responsive microbial fertilizer, which, based on Embodiment 1, further introduces an intelligent responsive microcapsule module capable of interacting with crops.

[0079] The preparation method is as follows: Accurately weigh 35g of modified biochar obtained from Preparation Example 1, 15g of compound microbial agent, 3g of chitosan, 2g of carboxymethyl cellulose, 10g of bentonite, 5g of oxygenating agent, 3g of dolomite powder, 3g of nano-silica, and 3g of intelligent responsive microcapsule powder obtained from Preparation Example 4. Place all the above powdered raw materials in a mixer and dry mix for 5 minutes. Then, slowly add 10g of deionized water under stirring, and continue wet mixing for 15 minutes to form loose clumps with uniform moisture content. Finally, granulate the material into granular intelligent responsive microbial fertilizer with a particle size of 2-4mm using an extrusion granulator.

[0080] Comparative Example 1 A method for preparing soil-improving microbial fertilizer includes the following steps: weighing 35g of biomass, 15g of compound microbial agent, 3g of chitosan, 2g of carboxymethyl cellulose, 10g of bentonite, 5g of oxygenating agent, 3g of dolomite powder, 3g of nano-silica, and 10g of deionized water and mixing them to obtain microbial fertilizer.

[0081] The biomass is coconut shells and waste mushroom sticks mixed in a 6:1 ratio and then crushed to 100 mesh. The compound microbial agent is a mixture of nitrogen-fixing bacteria, EM bacteria, and arbuscular mycorrhizal fungi in a mass ratio of 1:2:5, with a nitrogen-fixing bacteria content of 1.5 × 10⁻⁶. 8 cfu / g, EM bacteria content 5.5×10 8 cfu / g, arbuscular mycorrhizal fungi 5×10 6 cfu / g.

[0082] The oxygenating agent is a compound of magnesium peroxide, sodium percarbonate, and vermiculite in a mass ratio of 1:2:1.3. The average particle size of the nano-silica is 20 nm.

[0083] Comparative Example 2 A method for preparing soil-improving microbial fertilizer includes the following steps: weighing 35g activated carbon, 15g compound bacterial agent, 3g chitosan, 2g carboxymethyl cellulose, 10g bentonite, 5g oxygenating agent, 3g dolomite powder, 3g nano silica, and 10g deionized water and mixing them to obtain microbial fertilizer.

[0084] The biomass is coconut shells and waste mushroom sticks mixed in a 6:1 ratio and then crushed to 100 mesh. The compound microbial agent is a mixture of nitrogen-fixing bacteria, EM bacteria, and arbuscular mycorrhizal fungi in a mass ratio of 1:2:5, with a nitrogen-fixing bacteria content of 1.5 × 10⁻⁶. 8 cfu / g, EM bacteria content 5.5×10 8 cfu / g, arbuscular mycorrhizal fungi 5×10 6 cfu / g.

[0085] The oxygenating agent is a compound of magnesium peroxide, sodium percarbonate, and vermiculite in a mass ratio of 1:2:1.3. The average particle size of the nano-silica is 20 nm.

[0086] Comparative Example 3 A method for preparing soil-improving microbial fertilizer includes the following steps: weighing 35g of modified biochar from Preparation Example 1 and 15g of a product with a content of 1.5×10 8 Microbial fertilizer is obtained by mixing CFU / g nitrogen-fixing bacteria, 3g chitosan, 2g carboxymethyl cellulose, 10g bentonite, 5g oxygenating agent, 3g dolomite powder, 3g nano silica, and 10g deionized water.

[0087] The oxygenating agent is a compound of magnesium peroxide, sodium percarbonate, and vermiculite in a mass ratio of 1:2:1.3. The average particle size of the nano-silica is 20 nm.

[0088] Comparative Example 4 A method for preparing soil-improving microbial fertilizer includes the following steps: weighing 35g of modified biochar, 15g of compound microbial agent, 3g of chitosan, 2g of carboxymethyl cellulose, 10g of bentonite, 5g of magnesium peroxide, 3g of dolomite powder, 3g of nano silica, and 10g of deionized water from Preparation Example 1 and mixing them to obtain microbial fertilizer.

[0089] The compound microbial agent is a mixture of nitrogen-fixing bacteria, EM bacteria, and arbuscular mycorrhizal fungi in a mass ratio of 1:2:5, with a nitrogen-fixing bacteria content of 1.5 × 10⁻⁶. 8 cfu / g, EM bacteria content 5.5×10 8 cfu / g, arbuscular mycorrhizal fungi 5×10 6 cfu / g. The average particle size of the nano-silica is 20 nm.

[0090] Experimental effect verification The experiment was conducted from May to October 2024 at the Fenggu Yunong Technology Park in Hongdong Village, Jiangtun Town, Tengzhou City. The experimental field was previously planted with maize, and the soil was loamy, flat, and easily irrigated. Fertility was moderate, with soil organic matter content of 17.7 g / kg, total nitrogen of 1.059 g / kg, available phosphorus of 182.5 mg / kg, available potassium of 482 mg / kg, cation exchange capacity of 16.7 cmol(+) / kg, total soil bacteria count of 0.043 billion / g, bulk density of 1.33 g / cm³, and total water-soluble salts of 2.06 g / kg. The average temperature during the entire growing season was 13.6℃, ​​with a maximum of 37.2℃ and a minimum of -16.2℃, and an average humidity of 59.8%. Total rainfall was 213 mm, with an average monthly rainfall of 35.5 mm.

[0091] The crop and variety tested were Potato No. 6, with the original seed provided by Tengzhou Jinke Agricultural Technology Co., Ltd.

[0092] Test microbial fertilizers: Microbial fertilizers prepared in Examples 1-9 and Comparative Examples 1-4.

[0093] The experiment used single-row, single-ridge sowing with a ridge width of 65cm, row spacing of 80cm, and plant spacing of 25cm. Sowing took place on February 23, 2021, with emergence on March 22 and harvest on June 10. Other management practices were the same as in general field operations.

[0094] Plant dry matter and nutrient content determination: Samples were taken three times at 54 days (August 1), 68 days (August 15), and 82 days (August 30) after potato emergence. Two plants with similar growth were randomly selected from the two films in the middle of each plot. Each treatment was repeated three times. After being brought back to the laboratory, the plants were washed, dried, and their plant height and stem diameter were measured. The results are shown in Tables 1 and 2. Table 1. Effects of different microbial fertilizers on plant height (cm) Table 2. Effects of different microbial fertilizers on stem diameter (cm) Yield determination: During the harvest period, each experimental area was divided into three replicates, with 12m² sampled for yield determination. Tuber yield = 10000m² × tuber weight / 12m². Potato quality determination: Samples were taken from potato tubers 103 days after emergence, and the results are shown in Table 3. Table 3. Effects of different microbial fertilizers on potato tuber yield and marketable tuber rate. Detailed explanation of mechanism of action The intelligent responsive microcapsules added in this invention utilize the chemical communication mechanism between plants and soil microorganisms. Under specific physiological conditions, such as when crops (especially legumes or some grasses) encounter stress due to insufficient available phosphorus supply in the soil, their roots actively secrete large amounts of organic acids, such as citric acid, malic acid, and oxalic acid, into the rhizosphere microzone (i.e., the thin layer of soil immediately adjacent to the root surface). This process is an adaptive strategy evolved by plants to dissolve insoluble phosphates (such as calcium phosphate and iron phosphate) in the soil. The release of these organic acids causes a significant decrease in the pH value of the rhizosphere microzone in a short period of time, for example, from the overall soil pH of 6.8 to the pH of the root surface of 5.5 or even lower.

[0095] The PLGA microcapsules designed in this invention exhibit a chemical stability in their capsule walls that is highly sensitive to pH changes. The degradation of PLGA occurs through the hydrolysis of ester bonds in its molecular chain. This hydrolysis reaction is catalyzed by hydrogen ions under acidic conditions, significantly accelerating the reaction rate. This process can be described using a simplified kinetic model: release rate With degradation rate constant Proportional, and It is a function of pH. For example, when the pH decreases from 6.8 to 5.5, the hydrogen ion concentration... This has increased by approximately 20 times, which will lead to The value exhibits a significant, non-linear jump. In a specific calculation, if the half-life of the microcapsules is designed to be 30 days in a pH 6.8 environment, then in a rhizosphere microenvironment at pH 5.5, its half-life may be drastically shortened to less than 2 days.

[0096] This dramatic change in rate resulted in a concentrated, "pulse-like" release of the microbial activity enhancer encapsulated within the microcapsules. The released L-glutamic acid, yeast extract, and other substances rapidly increased the nutritional level of the compound microbial agent colonizing the surrounding modified biochar, providing a crucial material basis for the rapid proliferation and metabolic activities of aerobic microorganisms such as nitrogen-fixing bacteria and phosphate-solubilizing bacteria. Simultaneously, signaling molecules such as kaempferol further activated the symbiotic nitrogen-fixing genes of specific microorganisms (such as rhizobia), multiplying their functional expression efficiency. Ultimately, this targeted, localized microbial "activation" process, triggered by the crop's own demand signals, can most efficiently help crops overcome current nutrient stress, thus forming a closed-loop feedback control system of "crop demand - signal release - microcapsule response - microbial activation - demand fulfillment." This mechanism revolutionizes the action mode of microbial fertilizer from the traditional, static "warehouse" model to an intelligent, dynamic "precision airdrop" model, achieving a deep tapping of fertilizer potential.

[0097] In summary, different types of bio-fertilizers have different effects on potato yield and quality. The microbial fertilizers prepared in Examples 1-9 have a greater soil-improving effect than the microbial fertilizers prepared in Comparative Examples 1-4.

[0098] Unless otherwise specified, the raw materials used in this invention are all from commercially available conventional products.

[0099] Chitosan was purchased from Zhejiang Jinke Pharmaceutical Co., Ltd., CAS No.: 148411-57-8; Carboxymethyl cellulose was purchased from Jinan Mingjiang Chemical Co., Ltd., CAS No.: 9000-11-7; Bentonite and dolomite powder were purchased from Rongbang Mineral Products Processing Plant in Lingshou County.

[0100] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A soil-improving microbial fertilizer, characterized in that, The raw materials include the following parts by weight: Modified biochar 35-45 parts, compound microbial agent 15-25 parts, chitosan 3-7 parts, carboxymethyl cellulose 2-5 parts, bentonite 10-15 parts, oxygenating agent 5-10 parts, dolomite powder 3-8 parts, nano silica 3-8 parts, deionized water 10-25 parts.

2. The soil-improving microbial fertilizer according to claim 1, characterized in that, The method for preparing the modified biochar includes the following steps: S1 Raw material pretreatment: Mix coconut shells and waste mushroom sticks at a mass ratio of 7:3 and crush them to 80-100 mesh. Soak them in 5% citric acid solution for 10-12 hours to remove ash, and then dry them until the moisture content is <5%. S2 oxygen-limited pyrolysis: under nitrogen protection, the temperature is increased to 380-400℃ at 10℃ / min and held for 1-3h, then increased to 600-650℃ at 5℃ / min and held for 30-60min to form pyrolytic carbon with multi-level pores. S3 Chemically Modified Iron-Manganese Loading: Pyrolytic carbon is immersed in a mixture of 0.5 mol / L ferric nitrate solution and 0.3 mol / L potassium permanganate solution, and ultrasonically assisted to promote the entry of iron and manganese ions into the pores. After drying at 115-120℃, it is calcined at 350-380℃ for 2-3 hours to generate stable iron tetroxide / manganese dioxide composite oxide. S4 Post-activation treatment: Introduce 800℃ superheated steam for 15-30 min to increase the specific surface area to 800-1000 m² / g; Impregnate with Aspergillus niger fermentation broth for 24 h and then dry rapidly to form modified biochar with a biomimetic nanofiber structure on the surface.

3. The soil-improving microbial fertilizer according to claim 2, characterized in that, The volume ratio of the ferric nitrate solution to the potassium permanganate solution is 2:1; the ultrasonic-assisted treatment conditions in step S3 are 40 kHz and 60 °C for 1.5-2.5 h; and the concentration of the Aspergillus niger fermentation broth in step S4 is 8-12 g / L.

4. The soil-improving microbial fertilizer according to claim 1, characterized in that, The compound microbial agent is a mixture of nitrogen-fixing bacteria, effective microbial flora, and arbuscular mycorrhizal fungi in a mass ratio of (1-3):(2-5):(5-8); the content of nitrogen-fixing bacteria is not less than cfu / g, wherein the effective microbial community content is not less than cfu / g, the arbuscular mycorrhizal fungi are not less than cfu / g.

5. The soil-improving microbial fertilizer according to claim 1, characterized in that, The oxygenating agent is a compound of magnesium peroxide, sodium percarbonate and vermiculite in a mass ratio of 1-3:2:1.

3.

6. The soil-improving microbial fertilizer according to claim 1, characterized in that, The nano-silica has an average particle size of 20-50 nm and a specific surface area of ​​≥200 m² / g.

7. The microbial fertilizer according to claim 1 or the preparation method according to claim 10, characterized in that, The microbial fertilizer also includes 1-5 parts by weight of intelligent responsive microcapsules; the intelligent responsive microcapsules encapsulate a microbial activity enhancer and are configured to accelerate the release of the microbial activity enhancer in response to changes in the physicochemical parameters of the rhizosphere microenvironment caused by crop root exudates.

8. The microbial fertilizer or preparation method according to claim 7, characterized in that, The smart responsive microcapsule has a core-shell structure, and its shell material includes a pH-sensitive polymer and / or an enzymatically hydrolyzable polymer. The pH-sensitive polymer is selected from at least one of polylactic acid, polyglycolic acid, polylactic acid-glycolic acid copolymer, and polycaprolactone; the enzymatically hydrolyzable polymer is selected from at least one of chitosan, sodium alginate, and cellulose derivatives.

9. The microbial fertilizer or preparation method according to claim 7, characterized in that, The microbial activity enhancer includes amino acids, yeast extracts, and flavonoids for inducing the expression of specific functional genes in microorganisms, and / or the change in the physicochemical parameters of the rhizosphere microenvironment is a decrease in the pH value of the rhizosphere microzone; when the pH value of the smart responsive microcapsule shell material is lower than a preset release threshold, its hydrolysis or degradation rate increases nonlinearly.

10. A method for preparing a soil-improving microbial fertilizer, characterized in that, The preparation of the microbial fertilizer as described in claim 1 includes the following steps: weighing the raw materials in the specified weight proportions, and mixing modified biochar, compound microbial agent, chitosan, carboxymethyl cellulose, bentonite, oxygenating agent, dolomite powder, nano silica, and deionized water to obtain the microbial fertilizer.

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