Phenolic acid degradation fertilizer and preparation method thereof

Abstract

The invention provides a phenolic acid degradation fertilizer and a preparation method thereof, raw materials comprise metal cross-linked gel and engineering bacterium spores coated with the metal cross-linked gel, the engineering bacterium spores are one or more of white-rot fungus spores, trichoderma harzianum spores and aspergillus aculeatus spores, and the metal cross-linked gel comprises ferric chloride, sodium alginate and gelatin. Iron chloride, sodium alginate and gelatin form metal cross-linked gel to coat the engineering bacterium spores, phenolic acid pollutants in the environment can chelate metal ions in the metal cross-linked gel, and the engineering bacterium spores in the phenolic acid degradation fertilizer can be released only when the concentration of phenolic acid in the environment reaches a certain threshold value. Further, phenolic acid in the environment is decomposed, and it is ensured that all activity of functional bacteria is delivered to a phenolic acid enriched rhizosphere pollution area.

Description

Technical Field

[0001] This invention relates to the field of agricultural fertilizer technology, and more specifically to a phenolic acid degradable fertilizer and its preparation method. Background Technology

[0002] With the increasing intensification and modernization of modern agriculture, continuous cropping obstacles have become a global problem restricting the sustainable production of cash crops. One of the core causes is the continuous accumulation of phenolic acids such as vanillic acid and ferulic acid in the soil, which are secreted by plant roots and produced by the degradation of plant residues. These substances have an autotoxic effect on crops in the same or subsequent crops, inhibiting root growth, disrupting the soil micro-ecological balance, and ultimately leading to reduced crop yield and quality.

[0003] To address this challenge, bioremediation strategies utilizing functional microorganisms to degrade phenolic acids are considered an environmentally friendly solution. Currently, the mainstream technology for this type of fertilizer involves simply mixing or granulating bacteria, fungi, or their spores capable of degrading phenolic acids with organic or inorganic carriers such as peat moss, wheat bran, and humic acid. After application to the soil, the fertilizer relies on the natural diffusion and growth of the microorganisms to function. However, existing phenolic acid-degrading fertilizers have several significant shortcomings. First, the functional microorganisms in the fertilizer cannot respond to the concentration of phenolic acids in the soil. Regardless of whether it is needed, the microorganisms continuously release and consume energy, resulting in insufficient effective microbial agents during the critical period when phenolic acid degradation is truly required, leading to delayed remediation effects. Second, existing phenolic acid-degrading fertilizers cannot automatically adjust the release of microorganisms according to the phenolic acid concentration, making the entire system inefficient and potentially disruptive to the soil environment.

[0004] Therefore, further improvements and development are still needed. Summary of the Invention

[0005] To address the shortcomings of existing technologies and solve the aforementioned problems, a phenolic acid degradation fertilizer and its preparation method are proposed, and the following technical solution is provided: A phenolic acid degradable fertilizer, the raw materials of which include a metal cross-linking gel and engineered bacterial spores coated by the metal cross-linking gel, wherein the engineered bacterial spores are one or more of white rot fungal spores, Trichoderma harzianum spores and Aspergillus echinococcosis spores, and the metal cross-linking gel includes ferric chloride, sodium alginate and gelatin.

[0006] Furthermore, the mass ratio of ferric chloride, sodium alginate, and gelatin is 1:(5-10):(2-5).

[0007] Furthermore, the raw materials also include chitosan ethanol solution, laccase powder, and bio-carbon powder.

[0008] Furthermore, the mass ratio of ferric chloride, laccase powder, and biochar powder is 1:(0.05-0.3):(2-4).

[0009] Furthermore, by weight, the raw materials include 5-30 parts of the engineered bacteria, 1-10 parts of the ferric chloride, 10-40 parts of the sodium alginate, 5-20 parts of the gelatin, 0.5-3 parts of the laccase powder, and 4-20 parts of the bio-carbon powder.

[0010] This invention also provides a method for preparing a phenolic acid degradable fertilizer, the preparation method comprising the following steps: S1 Dissolve sodium alginate and gelatin in water at 50-60℃, cool to 30℃ to obtain a gel solution, and set aside; S2 mixes engineered bacterial spores with water to prepare a suspension; S3 The suspension and the gel were mixed and then dripped into a ferric chloride solution using a syringe pump to obtain gel microspheres; S4 Collect the gel microspheres, wash, dry and sieve to obtain phenolic acid degraded fertilizer.

[0011] Furthermore, laccase powder and biochar powder are added to the suspension in step S2.

[0012] Furthermore, the concentration of the ferric chloride solution in step S3 is 1 wt.%-10 wt.%, and the gel microspheres are allowed to stand in the ferric chloride solution for 20-40 minutes.

[0013] Furthermore, the drying process in step S4 involves placing the gel microspheres in an environment with a temperature of 35-45℃ and a relative humidity of 70-80% for 10-20 minutes, then freezing the treated gel microspheres to -20℃ at a cooling rate of 1℃ / min for freeze-drying, and finally drying the freeze-dried microspheres in an environment of 35-40℃ under inert gas fluidization until the water content is less than 8%.

[0014] Furthermore, a layer of chitosan-ethanol solution was sprayed onto the surface of the dried gel microspheres.

[0015] Due to the adoption of the above technical solutions, the beneficial technical effects of the present invention are as follows: 1. This invention uses ferric chloride, sodium alginate, and gelatin to form a metal cross-linked gel to encapsulate engineered bacterial spores. Phenolic acid pollutants in the environment will chelate the metal ions in the metal cross-linked gel. The release rate of engineered bacterial spores in the phenolic acid degradation fertilizer is controlled according to the concentration of phenolic acid in the environment, thereby decomposing phenolic acid in the environment and ensuring that all the activity of functional bacteria is delivered to the rhizosphere pollution area rich in phenolic acid.

[0016] 2. The phenolic acid degradation fertilizer of the present invention also contains laccase powder and biochar powder. Laccase initially degrades phenolic acids to generate more active quinone intermediates. These quinone substances have a strong effect on Fe... 3+Metal ions have stronger reducing and chelating abilities than phenolic acids, and can attack the Fe atoms in the gel network more quickly. 3+ Cross-linking points, thereby amplifying the trigger signal. Biochar has a huge specific surface area and rich pore structure, and has a strong adsorption effect on organic molecules such as phenolic acids. It can actively adsorb phenolic acid molecules dispersed in the rhizosphere environment. Biochar and laccase can be combined to control the sensitivity of the invention to phenolic acids by adjusting the content of the two.

[0017] 3. This invention utilizes high-humidity pretreatment drying, freeze-drying, and fluidized bed drying. High-humidity pretreatment should rapidly form a surface protective layer to prevent the internal structure from collapsing during subsequent drying. Then, freeze-drying can maintain the porous structure, and finally, fluidized bed drying ensures uniform moisture content. This drying process protects the activity of engineered bacteria and laccase, enhances the mechanical strength of phenolic acid-degraded fertilizer, and improves the yield. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application.

[0019] A phenolic acid degradable fertilizer comprises a metal cross-linking gel and engineered bacterial spores coated by the metal cross-linking gel. The engineered bacterial spores are one or more selected from white-rot fungal spores, *Trichoderma harzianum* spores, and *Aspergillus echinococcosis* spores. The metal cross-linking gel includes ferric chloride, sodium alginate, and gelatin. This invention uses ferric chloride, sodium alginate, and gelatin to form a metal cross-linking gel that coats the engineered bacterial spores. Phenolic acid pollutants in the environment chelate the metal ions in the metal cross-linking gel. Only when the concentration of phenolic acid in the environment accumulates to a certain threshold will the engineered bacterial spores in the phenolic acid degradable fertilizer be released, thereby decomposing the phenolic acid in the environment. This ensures that all the activity of the functional bacteria is delivered to the rhizosphere pollution zone rich in phenolic acid. Conventional biofertilizers apply live bacteria to the soil in a single application. Regardless of the presence or concentration of phenolic acid, the bacteria will initiate metabolism, resulting in a large amount of energy being consumed in non-targeted activities and rapid death in competition, with a very low proportion actually acting on pollutants. Furthermore, traditional microbial agents face declining vitality during storage, transportation, and initial application. Once in the soil, they are exposed to complex stresses, leading to a sharp drop in survival rates. In contrast, the phenolic acid-degrading fertilizer of this application preserves the engineered bacteria in a highly resilient spore form within a metal cross-linked gel before triggering, maintaining a deep dormant state with minimal energy consumption and long-term viability. Once the phenolic acid in the environment reaches a threshold triggering release, the engineered bacterial spores germinate rapidly at the pollution site and location, quickly forming a high-concentration localized bacterial community that degrades pollutants, demonstrating a powerful remediation capability and overcoming the problems of dispersed and low-activity bacterial communities in conventional applications.

[0020] The raw materials for phenolic acid degradation fertilizer also include chitosan ethanol solution, laccase powder, and biochar powder. The phenolic acid degradation fertilizer of this invention further contains laccase powder and biochar powder. Laccase performs preliminary degradation of phenolic acids to generate more active quinone intermediates. These quinone substances have a strong effect on Fe... 3+ Metal ions have stronger reducing and chelating abilities than phenolic acids, and can attack the Fe atoms in the gel network more quickly. 3 + Cross-linking points, thereby amplifying the trigger signal. Biochar has a huge specific surface area and rich pore structure, and has a strong adsorption effect on organic molecules such as phenolic acids. It can actively adsorb phenolic acid molecules dispersed in the rhizosphere environment. Biochar and laccase can be combined to control the sensitivity of the invention to phenolic acids by adjusting the content of the two.

[0021] This invention also provides a method for preparing a phenolic acid degradable fertilizer, the preparation method comprising the following steps: S1 Dissolve sodium alginate and gelatin in water at 50-60℃, cool to 30℃ to obtain a gel solution, and set aside; S2 mixes engineered bacterial spores with water to prepare a suspension; S3 The suspension and the gel were mixed and then dripped into a ferric chloride solution using a syringe pump to obtain gel microspheres; S4 Collect the gel microspheres, wash, dry and sieve to obtain phenolic acid degraded fertilizer.

[0022] In S1, the gel solution was cooled to 30°C before being mixed with engineered bacterial spores, which protected the spore activity. In S3, an Fe3+ coagulation bath was used to achieve controllable preparation of the gel structure of the phenolic acid degradation fertilizer.

[0023] Laccase powder and biochar powder were also added to the suspension in step S2. The engineered bacteria, laccase, and biochar were uniformly mixed before gel formation to ensure even distribution of the components within the particles.

[0024] The drying process in step S4 involves placing the gel microspheres in an environment with a temperature of 35-45℃ and a relative humidity of 70-80% for 10-20 minutes, then freezing the treated gel microspheres to -20℃ at a cooling rate of 1℃ / min for freeze-drying. The freeze-dried microspheres are then transferred to an environment of 35-40℃ and dried under inert gas fluidization for final drying until the moisture content is below 8%. This invention utilizes high-humidity pretreatment drying, freeze-drying, and fluidized bed drying. The high-humidity pretreatment should rapidly form a surface protective layer. This protective layer effectively prevents the collapse of the gel network and pore closure caused by rapid evaporation of internal moisture during the subsequent, more intense drying stages. This creates a relatively stable environment for the internal fungal spores and laccase, and initially shapes and enhances the mechanical strength of the gel microspheres. Then, freeze-drying maintains the porous structure. A slow, programmed cooling rate of 1℃ / min to -20℃ ensures that internal moisture forms fine, uniform ice crystals. Subsequent sublimation under vacuum leaves pores that perfectly replicate and fix the three-dimensional network of the wet gel, creating channels with a high specific surface area. This structure greatly facilitates the penetration of phenolic acid molecules in later applications. Finally, fluidized bed drying ensures uniform moisture content. This drying step protects the activity of engineered bacteria and laccase, enhances the mechanical strength of the phenolic acid-degraded fertilizer, and improves the yield.

[0025] A layer of chitosan-ethanol solution is sprayed onto the surface of the dried gel microspheres. The chitosan-ethanol solution forms an extremely thin, semi-permeable molecular membrane on the surface of the dried gel microspheres. This membrane effectively blocks ambient moisture, ensuring the stability of the product during storage and transportation, and enhancing the wear resistance of the microspheres.

[0026] Example 1 The preparation method of the phenolic acid degradation fertilizer in this embodiment includes the following steps: S1 Dissolve 30 parts sodium alginate and 10 parts gelatin in 2000 parts water at 55°C, and cool to 30°C to obtain a gel solution for later use; S2. A suspension is prepared by mixing 2 parts laccase powder, 10 parts biochar powder, 10 parts white rot fungal spores and 100 parts water. S3 After mixing the suspension and the gel, the mixture was dripped into a 5 wt.% ferric chloride solution (prepared by 5 parts ferric chloride and 95 parts water) using a syringe pump and allowed to stand for 30 minutes to obtain gel microspheres; S4 Collect the gel microspheres, wash and dry them, spray them with 1 wt.% chitosan ethanol solution, and sieve them to obtain phenolic acid degraded fertilizer.

[0027] The drying process involves placing the gel microspheres in an environment with a temperature of 40°C and a relative humidity of 75% for 15 minutes, then freezing the treated gel microspheres to -20°C at a cooling rate of 1°C / min for freeze-drying, and finally drying the freeze-dried microspheres at 35°C under nitrogen flow to achieve a final drying process until the moisture content of the phenolic acid degradation fertilizer is below 8%.

[0028] Example 2 The preparation method of the phenolic acid degradation fertilizer in this embodiment includes the following steps: S1 Dissolve 40 parts sodium alginate and 20 parts gelatin in 2000 parts water at 55°C, and cool to 30°C to obtain a gel solution for later use; S2. A suspension is prepared by mixing 3 parts laccase powder, 20 parts biochar powder, 30 parts white rot fungal spores and 100 parts water. S3 After mixing the suspension and the gel, the mixture was dripped into a 10 wt.% ferric chloride solution (prepared by 10 parts ferric chloride and 90 parts water) using a syringe pump and allowed to stand for 30 minutes to obtain gel microspheres; S4 Collect the gel microspheres, wash and dry them, spray them with 1 wt.% chitosan ethanol solution, and sieve them to obtain phenolic acid degraded fertilizer.

[0029] The drying process involves placing the gel microspheres in an environment with a temperature of 40°C and a relative humidity of 75% for 15 minutes, then freezing the treated gel microspheres to -20°C at a cooling rate of 1°C / min for freeze-drying, and finally drying the freeze-dried microspheres at 35°C under nitrogen flow to achieve a final drying process until the moisture content of the phenolic acid degradation fertilizer is below 8%.

[0030] Example 3 The preparation method of the phenolic acid degradation fertilizer in this embodiment includes the following steps: S1 Dissolve 10 parts sodium alginate and 5 parts gelatin in 2000 parts water at 55°C, and cool to 30°C to obtain a gel solution for later use; S2. Mix 0.5 parts laccase powder, 4 parts biochar powder, 5 parts white rot fungal spores and 100 parts water to prepare a suspension; S3 After mixing the suspension and the gel, the mixture was dripped into a 1 wt.% ferric chloride solution (prepared by 1 part ferric chloride and 99 parts water) using a syringe pump and allowed to stand for 30 minutes to obtain gel microspheres; S4 Collect the gel microspheres, wash and dry them, spray them with 1 wt.% chitosan ethanol solution, and sieve them to obtain phenolic acid degraded fertilizer.

[0031] The drying process involves placing the gel microspheres in an environment with a temperature of 40°C and a relative humidity of 75% for 15 minutes, then freezing the treated gel microspheres to -20°C at a cooling rate of 1°C / min for freeze-drying, and finally drying the freeze-dried microspheres at 35°C under nitrogen flow to achieve a final drying process until the moisture content of the phenolic acid degradation fertilizer is below 8%.

[0032] Example 4 The preparation method of the phenolic acid degradation fertilizer in this embodiment includes the following steps: S1 Dissolve 30 parts sodium alginate and 10 parts gelatin in 2000 parts water at 55°C, and cool to 30°C to obtain a gel solution for later use; S2. Prepare a suspension by mixing 10 parts of white rot fungal spores with 100 parts of water; S3 After mixing the suspension and the gel, the mixture was dripped into a 5 wt.% ferric chloride solution (prepared by 5 parts ferric chloride and 95 parts water) using a syringe pump and allowed to stand for 30 minutes to obtain gel microspheres; S4 Collect the gel microspheres, wash and dry them, spray them with 1 wt.% chitosan ethanol solution, and sieve them to obtain phenolic acid degraded fertilizer.

[0033] The drying process involves placing the gel microspheres in an environment with a temperature of 40°C and a relative humidity of 75% for 15 minutes, then freezing the treated gel microspheres to -20°C at a cooling rate of 1°C / min for freeze-drying, and finally drying the freeze-dried microspheres at 35°C under nitrogen flow to achieve a final drying process until the moisture content of the phenolic acid degradation fertilizer is below 8%.

[0034] Example 5 The preparation method of the phenolic acid degradation fertilizer in this embodiment includes the following steps: S1 Dissolve 30 parts sodium alginate and 10 parts gelatin in 2000 parts water at 55°C, and cool to 30°C to obtain a gel solution for later use; S2 is prepared by mixing 2 parts laccase powder, 10 parts biochar powder, 10 parts Trichoderma harzianum spores and 100 parts water to form a suspension; S3 After mixing the suspension and the gel, the mixture was dripped into a 5 wt.% ferric chloride solution (prepared by 5 parts ferric chloride and 95 parts water) using a syringe pump and allowed to stand for 30 minutes to obtain gel microspheres; S4 Collect the gel microspheres, wash, dry, and sieve to obtain phenolic acid degraded fertilizer.

[0035] The drying process involves placing the gel microspheres in an environment with a temperature of 40°C and a relative humidity of 75% for 15 minutes, then freezing the treated gel microspheres to -20°C at a cooling rate of 1°C / min for freeze-drying, and finally drying the freeze-dried microspheres at 35°C under nitrogen flow to achieve a final drying process until the moisture content of the phenolic acid degradation fertilizer is below 8%.

[0036] Example 6 The preparation method of the phenolic acid degradation fertilizer in this embodiment includes the following steps: S1 Dissolve 30 parts sodium alginate and 10 parts gelatin in 2000 parts water at 55°C, and cool to 30°C to obtain a gel solution for later use; S2. A suspension is prepared by mixing 2 parts laccase powder, 10 parts biochar powder, 10 parts Aspergillus echinococcosis spores and 100 parts water. S3 After mixing the suspension and the gel, the mixture was dripped into a 5 wt.% ferric chloride solution (prepared by 5 parts ferric chloride and 95 parts water) using a syringe pump to obtain gel microspheres; S4 Collect the gel microspheres, wash, dry, and sieve to obtain phenolic acid degraded fertilizer.

[0037] The drying process involves placing the gel microspheres in an environment with a temperature of 35°C and a relative humidity of 70% for 15 minutes, then freezing the treated gel microspheres to -20°C at a cooling rate of 1°C / min for freeze-drying, and finally drying the freeze-dried microspheres at 40°C under nitrogen flow to achieve a final drying process until the moisture content of the phenolic acid degradation fertilizer is below 8%.

[0038] Comparative Example 1 Compared with Example 1, the raw materials in this comparative example do not contain ferric chloride, and all other conditions are the same as in Example 1. The specific steps are as follows: S1 Dissolve 30 parts sodium alginate and 10 parts gelatin in 2000 parts water at 55°C, and cool to 30°C to obtain a gel solution for later use; S2. A suspension is prepared by mixing 2 parts laccase powder, 10 parts biochar powder, 10 parts white rot fungal spores and 100 parts water. S3 The suspension and gel were mixed and then dripped into water using a syringe pump. After standing for 30 minutes, gel microspheres were obtained. S4 Collect the gel microspheres, wash and dry them, spray them with 1 wt.% chitosan ethanol solution, and sieve them to obtain phenolic acid degraded fertilizer.

[0039] The drying process involves placing the gel microspheres in an environment with a temperature of 40°C and a relative humidity of 75% for 15 minutes, then freezing the treated gel microspheres to -20°C at a cooling rate of 1°C / min for freeze-drying, and finally drying the freeze-dried microspheres at 35°C under nitrogen flow to achieve a final drying process until the moisture content of the phenolic acid degradation fertilizer is below 8%.

[0040] Comparative Example 2 Compared with Example 1, the raw materials in this comparative example contain 20 parts of ferric chloride, 50 parts of sodium alginate, and 20 parts of gelatin. All other conditions are the same as in Example 1. The specific steps are as follows: S1 Dissolve 50 parts sodium alginate and 20 parts gelatin in 2000 parts water at 55°C, and cool to 30°C to obtain a gel solution for later use; S2. A suspension is prepared by mixing 2 parts laccase powder, 10 parts biochar powder, 10 parts white rot fungal spores and 100 parts water. S3 After mixing the suspension and the gel, the mixture was dripped into a 20 wt.% ferric chloride solution (prepared by 20 parts ferric chloride and 80 parts water) using a syringe pump and allowed to stand for 30 minutes to obtain gel microspheres; S4 Collect the gel microspheres, wash and dry them, spray them with 1 wt.% chitosan ethanol solution, and sieve them to obtain phenolic acid degraded fertilizer.

[0041] The drying process involves placing the gel microspheres in an environment with a temperature of 40°C and a relative humidity of 75% for 15 minutes, then freezing the treated gel microspheres to -20°C at a cooling rate of 1°C / min for freeze-drying, and finally drying the freeze-dried microspheres at 35°C under nitrogen flow to achieve a final drying process until the moisture content of the phenolic acid degradation fertilizer is below 8%.

[0042] Comparative Example 3 Compared with Example 1, the raw materials in this comparative example contain 10 parts of laccase powder and 20 parts of bio-carbon powder. All other conditions are the same as in Example 1. The specific steps are as follows: S1 Dissolve 30 parts sodium alginate and 10 parts gelatin in 2000 parts water at 55°C, and cool to 30°C to obtain a gel solution for later use; S2 is prepared by mixing 10 parts laccase powder, 20 parts biochar powder, 10 parts white rot fungal spores and 100 parts water to form a suspension; S3 After mixing the suspension and the gel, the mixture was dripped into a 5 wt.% ferric chloride solution (prepared by 5 parts ferric chloride and 95 parts water) using a syringe pump and allowed to stand for 30 minutes to obtain gel microspheres; S4 Collect the gel microspheres, wash and dry them, spray them with 1 wt.% chitosan ethanol solution, and sieve them to obtain phenolic acid degraded fertilizer.

[0043] The drying process involves placing the gel microspheres in an environment with a temperature of 40°C and a relative humidity of 75% for 15 minutes, then freezing the treated gel microspheres to -20°C at a cooling rate of 1°C / min for freeze-drying, and finally drying the freeze-dried microspheres at 35°C under nitrogen flow to achieve a final drying process until the moisture content of the phenolic acid degradation fertilizer is below 8%.

[0044] Comparative Example 4 Compared with Example 1, the drying process in this comparative example preparation method is only conventional hot air fluidized bed drying, and the specific steps are as follows: S1 Dissolve 30 parts sodium alginate and 10 parts gelatin in 2000 parts water at 55°C, and cool to 30°C to obtain a gel solution for later use; S2. A suspension is prepared by mixing 2 parts laccase powder, 10 parts biochar powder, 10 parts white rot fungal spores and 100 parts water. S3 After mixing the suspension and the gel, the mixture was dripped into a 5 wt.% ferric chloride solution (prepared by 5 parts ferric chloride and 95 parts water) using a syringe pump and allowed to stand for 30 minutes to obtain gel microspheres; S4 Collect the gel microspheres, wash and dry them, spray them with 1 wt.% chitosan ethanol solution, and sieve them to obtain phenolic acid degraded fertilizer. The surface of the obtained phenolic acid degraded fertilizer is cracked.

[0045] The drying process involves placing the gel microspheres in hot air at a working temperature of 40°C and drying them until the moisture content is below 8%.

[0046] Comparative Example 5 Compared with Example 1, the drying process in this comparative example preparation method does not include freeze-drying. The specific steps are as follows: S1 Dissolve 30 parts sodium alginate and 10 parts gelatin in 2000 parts water at 55°C, and cool to 30°C to obtain a gel solution for later use; S2. A suspension is prepared by mixing 2 parts laccase powder, 10 parts biochar powder, 10 parts white rot fungal spores and 100 parts water. S3 After mixing the suspension and the gel, the mixture was dripped into a 5 wt.% ferric chloride solution (prepared by 5 parts ferric chloride and 95 parts water) using a syringe pump and allowed to stand for 30 minutes to obtain gel microspheres; S4 Collect the gel microspheres, wash and dry them, spray them with 1 wt.% chitosan ethanol solution, and sieve them to obtain phenolic acid degraded fertilizer.

[0047] The drying process involves placing the gel microspheres in an environment with a temperature of 40°C and a relative humidity of 75% for 15 minutes, and then transferring the treated gel microspheres to an environment with a temperature of 35°C and a nitrogen flow for drying, until the moisture content of the phenolic acid degradation fertilizer is less than 8%.

[0048] The preparation methods and raw materials of the phenolic acid degradation fertilizers obtained in Examples 1-6 and Comparative Examples 1-5 are summarized in Table 1-2 below.

[0049] Table 1 Summary of preparation methods and raw materials for phenolic acid degradation fertilizers in Examples 1-6 Table 2 Summary of preparation methods and raw materials for phenolic acid degradation fertilizers in Comparative Examples 1-5 Test Example 1 The phenolic acid degradation fertilizers prepared in Examples 1-6 and Comparative Examples 1-5 were subjected to disintegration efficiency tests. The pH of the soil was simulated in the conical flask with a buffer solution, and target ferulic acid solutions of 50 μg / mL, 100 μg / mL, 150 μg / mL, 200 μg / mL and 250 μg / mL were prepared respectively. 1 g of sample was added to each concentration of ferulic acid solution, and the gel disintegration start time and complete disintegration time were observed. The results are shown in Table 3.

[0050] Table 3. Gel disintegration time of phenolic acid degradable fertilizers prepared in Examples 1-6 and Comparative Examples 1-5 Example 1 of this invention was stable at 50 μg / mL and began to disintegrate at 100 μg / mL, with the disintegration time decreasing as the concentration increased. Example 2 had a higher component content, resulting in a denser gel network, a higher disintegration threshold, and slower disintegration. Example 3 had a lower component content, a weaker gel network, and disintegrated fastest. Example 4, lacking laccase and biochar, disintegrated slowly and incompletely. Example 5, without chitosan coating, disintegrated faster than Example 1 at the same concentration, indicating that laccase and biochar significantly accelerate disintegration, and that the chitosan membrane provides sustained-release protection. Example 6, without static curing, disintegrated slower than Example 1, indicating that sufficient cross-linking time is crucial for forming a stable gel network. However, the disintegration rate of the phenolic acid-degrading fertilizers in Examples 1-6 was affected by the concentration of phenolic acid in the environment. Comparative Example 1 did not contain Fe. 3+ This resulted in the phenolic acid degradation fertilizer not disintegrating at all, confirming that Fe... 3+ Cross-linking is a necessary condition for the disintegration of phenolic acid-degrading fertilizers under the influence of phenolic acids. In Comparative Example 2, Fe... 3+ Excessive amounts of metal cross-linking gel resulted in overly dense cross-linking, causing the phenolic acid-degrading fertilizer to disintegrate slowly only at high concentrations. In Comparative Example 3, excessive laccase and biochar made the present invention overly sensitive to phenolic acids in the environment, causing the phenolic acid-degrading fertilizer to disintegrate rapidly even at low concentrations. The phenolic acid-degrading fertilizers obtained in Comparative Example 4 (hot air drying only) and Comparative Example 5 (no freeze-drying) showed significantly worse disintegration performance than those of Example 1, especially at low to medium concentrations, exhibiting sluggish or incomplete responses. This demonstrates that the high-humidity pretreatment and freeze-drying processes of the present invention are crucial for maintaining the porous structure of the gel and ensuring rapid phenolic acid penetration and triggering.

[0051] Test Example 2 The phenolic acid degrading fertilizers prepared in Examples 1-6 and Comparative Examples 1-5 of this invention were used as test samples. A pot experiment was conducted with 11 treatments. Based on sterilized farmland soil, a mixture of exogenous phenolic acids such as vanillic acid and ferulic acid was added to prepare simulated continuous cropping obstacles, ensuring an initial total phenolic acid concentration of 200 μg / g. Each test fertilizer was mixed thoroughly with 3.0 kg of simulated soil at a dosage of 100 mg / kg soil and then potted. The wheat variety Zhoumai 18, sensitive to continuous cropping obstacles, was selected. After surface disinfection and germination, 10 seeds were sown per pot. After emergence, seedlings were thinned to 5 plants per pot. The potted plants were placed in a temperature- and light-controlled cultivation room, with day and night temperatures controlled at (22±2)℃ and (16±2)℃, respectively, and a photoperiod of 14 h / 10 h (light / dark). The soil moisture content was maintained at 60%-65% of field capacity using a weighing method. No additional organic or microbial fertilizers were added except for the tested fertilizer. The phenolic acid degradation fertilizers prepared in Examples 1-6 and Comparative Examples 1-5 were used in pot simulation experiments, with conventional microbial fertilizers as the control.

[0052] Phenolic acid-degrading fertilizers from Examples 1-6 and Comparative Examples 1-5, and conventional microbial fertilizers were applied to simulated soils with continuous cropping obstacles. Wheat varieties sensitive to continuous cropping obstacles were selected, and seeds were sterilized and pre-germinated. Each pot contained 3 kg of soil. Fertilizers were mixed with the soil according to the recommended dosage. Ten seeds with white sprouts were sown per pot. After emergence, seedlings were thinned to 5 plants per pot and placed in a temperature- and light-controlled cultivation room or greenhouse. Routine water and fertilizer management was implemented, avoiding other stresses. Root dry weight and root area were recorded at the wheat jointing stage. Destructive sampling was performed at the wheat jointing stage (45 days after sowing). The plant roots were completely removed and washed, and the total root surface area of ​​each plant was measured using a root scanning analysis system. The roots were then dried at 65℃ to constant weight, and the dry weight of each plant was recorded. The total root surface area and dry weight of each plant are shown in Table 4 below.

[0053] Table 4 Total root surface area and dry weight of single root system in Test Example 2 The wheat treated in all Examples 1-6 of this invention showed significantly better root dry weight and total root surface area than the comparative treatments, indicating that the formulation and process of this invention can effectively alleviate phenolic acid stress and promote wheat root development. Comparative Example 1 was free of Fe. 3+ The cross-linking effect was the worst, which directly proves that Fe 3+ Cross-linked gels are the essential structural basis for the effectiveness of this invention. Comparative Example 4, which used conventional hot-air dried gel microspheres, also showed poor phenolic acid degradation fertilizer performance, highlighting the crucial role of the composite drying process of this invention in maintaining the activity of the microbial agent and enzymes, and preserving the porous responsive structure of the gel.

[0054] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A phenolic acid degradable fertilizer, characterized in that, The raw materials include a metal cross-linked gel and engineered bacterial spores coated with the metal cross-linked gel. The engineered bacterial spores are one or more of white rot fungal spores, Trichoderma harzianum spores, and Aspergillus echinococcosis spores. The metal cross-linked gel includes ferric chloride, sodium alginate, and gelatin.

2. The phenolic acid degradable fertilizer according to claim 1, characterized in that, The mass ratio of ferric chloride, sodium alginate and gelatin is 1:(5-10):(2-5).

3. The phenolic acid degradation fertilizer according to claim 1, characterized in that, The raw materials also include chitosan ethanol solution, laccase powder, and biochar powder.

4. The phenolic acid degradation fertilizer according to claim 3, characterized in that, The mass ratio of ferric chloride, laccase powder, and biochar powder is 1:(0.05-0.3):(2-4).

5. The phenolic acid degradation fertilizer according to claim 3, characterized in that, By weight, the raw materials include 5-30 parts of the engineered bacteria, 1-10 parts of the ferric chloride, 10-40 parts of the sodium alginate, 5-20 parts of the gelatin, 0.5-3 parts of the laccase powder, and 4-20 parts of the bio-carbon powder.

6. A method for preparing a phenolic acid degradable fertilizer according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: S1 Dissolve sodium alginate and gelatin in water at 50-60℃, cool to 30℃ to obtain a gel solution, and set aside; S2 mixes engineered bacterial spores with water to prepare a suspension; S3 The suspension and the gel were mixed and then dripped into a ferric chloride solution using a syringe pump to obtain gel microspheres; S4 Collect the gel microspheres, wash, dry and sieve to obtain phenolic acid degraded fertilizer.

7. The method for preparing a phenolic acid degradable fertilizer according to claim 6, characterized in that, Laccase powder and biochar powder were also added to the suspension in step S2.

8. The method for preparing a phenolic acid degradable fertilizer according to claim 6, characterized in that, The concentration of the ferric chloride solution in step S3 is 1 wt.%-10 wt.%, and the gel microspheres are allowed to stand in the ferric chloride solution for 20-40 minutes.

9. The method for preparing a phenolic acid degradable fertilizer according to claim 6, characterized in that, The drying process in step S4 involves placing the gel microspheres in an environment with a temperature of 35-45℃ and a relative humidity of 70-80% for 10-20 minutes, then freezing the treated gel microspheres to -20℃ at a cooling rate of 1℃ / min for freeze-drying, and finally drying the freeze-dried microspheres in an environment of 35-40℃ under inert gas fluidization until the water content is below 8%.

10. The method for preparing a phenolic acid degradable fertilizer according to claim 6, characterized in that, A layer of chitosan-ethanol solution was sprayed onto the surface of the dried gel microspheres.

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