A modified peat-based soil conditioner based on laccase-degraded lignin products and a method for its preparation

Abstract

This invention relates to a modified peat-based soil conditioner based on laccase-degraded lignin products and its preparation method, belonging to the field of saline-alkali soil improvement technology. To address the problems of insufficient phosphorus supply and difficulty in mitigating phytotoxicity of lignin degradation solutions in existing peat conditioners, this invention provides a method for preparing a modified peat-based soil conditioner based on laccase-degraded lignin products. The method involves enzymatically hydrolyzing and liquefying lignin using laccase in the synergistic effect of syringaldehyde mediator. The supernatant from this enzymatic hydrolysis is then mixed and shaken with peat to ensure sufficient contact and reaction between the degradation solution and the peat, resulting in the modified peat-based soil conditioner. This invention yields an active supernatant rich in carboxyl and quinone groups, which is used to modify peat. Through the adsorption and fixation of sodium ions in the soil and the release and activation of fixed phosphorus by the modified peat, the improvement effect on saline-alkali soil is demonstrated from three dimensions: improved chemical properties, promoted crop growth, and optimized ion balance.

Description

Technical Field

[0001] This invention belongs to the field of saline-alkali soil improvement technology, and particularly relates to a modified peat-based soil conditioner based on laccase-degraded lignin products and its preparation method. Background Technology

[0002] Saline-alkali soil improvement is a crucial issue in the field of sustainable agricultural development. Currently, commonly used saline-alkali soil improvement measures mainly include soil replacement, salt drainage through water conservancy projects, application of chemical amendments, and organic fertilization. However, these methods generally suffer from high costs, long cycles, or unstable effects. Peat, as a natural resource rich in organic matter and humic acid, is widely used for saline-alkali soil improvement, as it can improve soil structure, increase cation exchange capacity, and enhance nutrient retention. However, natural peat contains a large amount of phosphorus fixed by iron and aluminum ions. This phosphorus exists in an inert form and is difficult for crop roots to directly absorb and utilize, resulting in limited effectiveness of peat amendments in improving phosphorus supply to saline-alkali soils. Existing research on peat activation mainly employs methods such as acid leaching, alkali dissolution, or microbial fermentation. However, these methods generally suffer from drawbacks such as complex operation, high risk of secondary pollution, or low activation efficiency. Therefore, there is an urgent need to find a green and efficient peat-fixed phosphorus activation technology.

[0003] Lignin, the most abundant aromatic polymer in nature, has a three-dimensional network structure composed of highly cross-linked phenylpropane units connected by stable ether and carbon-carbon bonds. This structure endows lignin with strong resistance to degradation, making it difficult for microorganisms or enzymes to efficiently decompose it under natural conditions. Laccase, a multi-copper oxidase, can catalyze the oxidation of phenolic hydroxyl groups and ether bonds in lignin molecules with the assistance of mediators, causing the lignin macromolecular skeleton to break down and degrade. Current research focuses on the enzymatic hydrolysis of lignin in the paper industry, the degradation of organic pollutants in wastewater, and the bioremediation of harmful substances such as polycyclic aromatic hydrocarbons in contaminated soil. However, the practical application of laccase in open environments is limited by technical bottlenecks such as poor enzyme activity stability and stringent reaction conditions. More importantly, lignin degradation products contain a large number of small phenolic molecules, and studies have shown that these substances have potential toxicity to plant growth. This has led researchers to naturally avoid directly using lignin degradation solutions for agricultural soil improvement. Research on lignin enzymatic hydrolysis products has long been limited to the fields of bioenergy and chemical synthesis, and their potential as active components for soil improvement has not been fully recognized. Summary of the Invention

[0004] To address the problems of insufficient phosphorus supply in existing peat amendments and difficulty in avoiding plant toxicity of lignin degradation solutions, this invention provides a modified peat-based soil amendment based on laccase-degraded lignin products and its preparation method.

[0005] The technical solution of the present invention:

[0006] A method for preparing a modified peat-based soil conditioner based on laccase-degraded lignin products includes the following steps:

[0007] Step 1: Mix the lignin raw material with an acidic buffer solution with a pH of 4.5-5.5, add laccase and eugenol, and perform enzymatic hydrolysis at 45-55℃ for 20-40 hours to obtain the enzymatic hydrolysis reaction solution.

[0008] Step 2: Separate the enzymatic hydrolysis reaction solution obtained in Step 1 into solid and liquid phases, and collect the supernatant, which is the laccase degradation solution.

[0009] Step 3: Mix the laccase degradation solution obtained in Step 2 with peat at a volume-to-mass ratio of 1 mL:1 g to 15 mL:1 g, and shake to ensure that the degradation solution and peat are in full contact and react, thereby obtaining a modified peat-based soil conditioner.

[0010] Furthermore, in step one, the mass ratio of laccase to lignin raw material is 5-25:1, and the mass ratio of eugenol to lignin raw material is 0.02-0.2:1.

[0011] Furthermore, in step one, the mass ratio of laccase to lignin raw material is 25:1, and the mass ratio of eugenol to lignin raw material is 0.2:1.

[0012] Furthermore, in step three, the volume-to-mass ratio of the laccase degradation solution to the peat is 15 mL: 1 g.

[0013] Furthermore, the acidic buffer solution mentioned in step one is a citric acid-sodium citrate buffer solution with a pH of 5.0.

[0014] Furthermore, the enzymatic hydrolysis reaction described in step one takes 30 hours.

[0015] Furthermore, the oscillation temperature in step three is 20~30℃, and the oscillation time is 20~26 hours.

[0016] A modified peat-based soil conditioner is prepared by the preparation method provided by this invention.

[0017] The beneficial effects of this invention are:

[0018] This invention utilizes laccase in synergistic action with eugenol to enzymatically hydrolyze and liquefy lignin, directionally degrading large lignin molecules into water-soluble small molecule fragments rich in active functional groups such as carboxyl and quinone groups. The supernatant from this enzymatic hydrolysis is then mixed with peat in a specific ratio and agitated to allow the active small molecules to be fully adsorbed and undergo a coupled oxidation reaction with the peat, grafting carboxyl and quinone groups into the peat framework, significantly improving the cation exchange capacity and hydrophilicity of the peat. Simultaneously, the carboxyl groups in the degradation solution can chelate iron and aluminum ions bound to phosphate, weakening the bond strength of metal phosphate ions through competitive coordination, thus converting the inert phosphorus fixed in the peat into an active form that can be absorbed by crops. Therefore, this invention simultaneously solves the triple technical challenges of the difficulty in utilizing fixed phosphorus in peat by crops, the non-use of lignin degradation products for soil improvement due to phytotoxicity, and the risk of secondary pollution from existing peat activation methods.

[0019] Infrared and ultraviolet spectral analyses showed that the laccase-syringaldehyde synergistic system significantly reduced phenolic hydroxyl groups, benzene ring C=C groups, and ether bonds in lignin, while significantly increasing carboxyl and quinone groups. Furthermore, the degradation degree deepened with increasing laccase and syringaldehyde dosage. After the peat reacted with the enzymatic hydrolysate, the content of carboxyl and quinone groups on its surface continuously increased with increasing solid-liquid ratio, proving that the peat was effectively oxidized and modified. Pot experiments showed that the application of this amendment significantly increased the available phosphorus content in the soil, resulting in soybean root length reaching 1166.68 cm, root tip number reaching 300.33, and chlorophyll content increasing by 27.3% compared to the control. Sodium ion content significantly decreased, while potassium ion content remained at a high level, and the sodium-potassium ratio decreased significantly. All growth indicators were significantly better than those of the unmodified peat treatment.

[0020] This invention realizes the high-value agricultural utilization of lignin waste and the in-situ activation of fixed phosphorus in peat. At the same time, it significantly improves the adsorption and exchange capacity of peat for sodium ions in saline-alkali soil, and has the dual functions of phosphorus supply enhancement and saline-alkali stress relief. Moreover, the preparation process is mild, simple and environmentally friendly, avoiding the secondary pollution risk of traditional acid leaching and alkali dissolution methods. It provides a new material and method for saline-alkali soil improvement that is efficient, safe and sustainable, and has good prospects for promotion and application. Attached Figure Description

[0021] Figure 1 Infrared spectra of solid products from different reaction systems;

[0022] Figure 2 A comparison chart showing the content of water-soluble phenols in lignin raw materials and the solid residue from laccase hydrolysis;

[0023] Figure 3 These are partial UV scans of the liquid products in different reaction systems.

[0024] Figure 4The UV-Vis expansion scans of liquid products from different reaction systems under two solid-liquid ratio conditions are shown.

[0025] Figure 5 Infrared spectra of the solid residue products in reaction systems with different amounts of laccase and syringaldehyde;

[0026] Figure 6 A comparison of the UV transmittance of liquid products from reaction systems with different amounts of laccase and eugenol.

[0027] Figure 7 Infrared spectra of residual solids in peat modified with enzymatic hydrolysate under different solid-liquid ratios;

[0028] Figure 8 A comparison of the UV transmittance of the liquid after the reaction of peat modified with enzymatic hydrolysate under different solid-liquid ratios.

[0029] Figure 9 A graph showing the changes in available phosphorus content in peat activated by laccase and eugenol under different temperature conditions.

[0030] Figure 10 Real photos of the overall root system morphology of each group of soybean seedlings;

[0031] Figure 11 A top-down view of the above-ground growth of a potted soybean plant;

[0032] Figure 12 A side view of the entire growth of a potted soybean plant;

[0033] Figure 13 Comparison of aboveground and underground lengths of soybean seedlings under different treatments;

[0034] Figure 14 A comparison chart of the fresh weight of the above-ground and underground parts of a soybean plant;

[0035] Figure 15 A comparison chart of the dry weight of the aboveground and underground parts of a soybean plant;

[0036] Figure 16 Scan images of soybean root morphology in different treatment groups;

[0037] Figure 17 Comparison of chlorophyll content in soybean leaves from different treatment groups;

[0038] Figure 18 Comparison of available phosphorus content in soybean rhizosphere soil among different treatment groups;

[0039] Figure 19 A comparison of sodium ion content in the aboveground and underground parts of soybean plants from different treatment groups;

[0040] Figure 20Comparison of potassium ion content in the aboveground and underground parts of soybean plants from different treatment groups;

[0041] Figure 21 A comparison of the sodium-potassium ratio in the aboveground and underground parts of soybean plants from different treatment groups;

[0042] Figure 22 Comparison of sodium ion migration index in soybean plants from different treatment groups;

[0043] Figure 23 A comparison of potassium ion migration index in soybean plants from different treatment groups;

[0044] Figure 24 Comparison of sodium ion content in soybean rhizosphere soil of different treatment groups;

[0045] Figure 25 A heatmap showing the correlation analysis of various indicators for different treatment groups. Detailed Implementation

[0046] The technical solution of the present invention will be further described below with reference to embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention. In the following embodiments, the process equipment or apparatus not specifically specified are all conventional equipment or apparatus in the art. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commercially available; unless otherwise specified, the technical means used in the embodiments of the present invention are all conventional means well known to those skilled in the art.

[0047] Example 1

[0048] This embodiment provides a modified peat-based soil conditioner based on laccase-degraded lignin products, which is prepared through the following steps:

[0049] Step 1: Enzymatic hydrolysis and liquefaction of lignin: Take 0.5g of lignin raw material, add 100 mL of citric acid-sodium citrate buffer solution with pH 5.0, stir and mix well, then add 2.5g of laccase with an enzyme activity of 10000U / kg and 0.01g of eugenol, and carry out the enzymatic hydrolysis reaction for 30h under constant temperature shaking at 50℃ to obtain the enzymatic hydrolysis reaction solution.

[0050] Step 2, solid-liquid separation and degradation solution acquisition: Centrifuge the enzymatic reaction solution obtained in Step 1 at 8000 r / min for 15 min, and collect the supernatant rich in small molecule aromatic compounds, which is the laccase degradation solution.

[0051] Step 3: Loading peat with degradation solution: Take 5 mL of laccase degradation solution obtained in step 2 and mix it with 5 g of peat. Place it in a constant temperature shaker and shake at 25℃ and 200 r / min for 24 h to allow the degradation solution to fully adsorb and react, and obtain a modified peat-based soil conditioner.

[0052] The peat used in this embodiment is commercially available herbal peat, purchased from Ningbo Xiaorang Ecological Technology Co., Ltd., with an organic matter content ≥45%, humic acid content ≥30%, and pH (water extraction) of 5.5-6.5.

[0053] Soil improvement experiments were conducted using the modified peat-based soil conditioner prepared in this embodiment. A saline-alkali simulated matrix was obtained by mixing saline soil and vermiculite at a mass ratio of 1:2.5. The saline soil was a typical soda-type saline-alkali soil, collected from saline-alkali grassland in the Anda area of ​​the Songnen Plain, Heilongjiang Province. This type of soil has poor physical properties, low permeability, and a significant inhibitory effect on plant growth.

[0054] The main characteristics of the saline soil used in this embodiment are: pH value between 9.0 and 10.5, total salt content of 0.7 to 1.0%; salt composition mainly of sodium carbonate and sodium bicarbonate, sodium ions and bicarbonate ions account for 85 to 95% of the total soluble salt, and alkalinity (ESP) is higher than 45%.

[0055] The vermiculite used in this embodiment is conventional commercially available horticultural vermiculite with a particle size of 1-3 mm, a SiO2 content of ≥37%, and a cation exchange capacity of ≥100 mmol / 100g.

[0056] Add 5g of the modified peat-based soil conditioner prepared in this embodiment to 450g of salinization simulation matrix, mix well, and then put into a potted container. Use soybean as the test crop for cultivation experiments to evaluate the effect of this conditioner on crop growth and soil properties under salinity stress.

[0057] Example 2

[0058] The only difference between this embodiment and Example 1 is that in step three, loading peat with degradation solution: take 10 mL of laccase degradation solution obtained in step two and mix it with 5 g of peat, place it in a constant temperature shaker and shake it at 25°C and 200 r / min for 24 h to allow the degradation solution to be fully adsorbed and reacted, and obtain modified peat-based soil conditioner.

[0059] In the soil improvement experiment of this embodiment, 5g of the modified peat-based soil conditioner prepared in this embodiment was added to 450g of salinization simulation matrix.

[0060] Example 3

[0061] The only difference between this embodiment and Example 1 is that in step three, loading peat with degradation solution: take 25 mL of laccase degradation solution obtained in step two and mix it with 5 g of peat, place it in a constant temperature shaker and shake it at 25°C and 200 r / min for 24 h to allow the degradation solution to be fully adsorbed and reacted, and obtain modified peat-based soil conditioner.

[0062] In the soil improvement experiment of this embodiment, 5g of the modified peat-based soil conditioner prepared in this embodiment was added to 450g of salinization simulation matrix.

[0063] Example 4

[0064] The only difference between this embodiment and Example 1 is that in step three, loading peat with degradation solution: take 60 mL of laccase degradation solution obtained in step two and mix it with 5 g of peat, place it in a constant temperature shaker and shake it at 25°C and 200 r / min for 24 h to allow the degradation solution to be fully adsorbed and reacted, and obtain modified peat-based soil conditioner.

[0065] In the soil improvement experiment of this embodiment, 5g of the modified peat-based soil conditioner prepared in this embodiment was added to 450g of salinization simulation matrix.

[0066] Example 5

[0067] This embodiment provides a modified peat-based soil conditioner based on laccase-degraded lignin products, which is prepared through the following steps:

[0068] Step 1: Enzymatic hydrolysis and liquefaction of lignin: Take 0.5g of lignin raw material, add 100mL of citric acid-sodium citrate buffer solution with pH 5.0, stir and mix well, then add 12.5g of laccase with an enzyme activity of 10000U / kg and 0.01g of eugenol, and carry out the enzymatic hydrolysis reaction for 30h under constant temperature shaking at 50℃ to obtain the enzymatic hydrolysis reaction solution.

[0069] Step 2, solid-liquid separation and degradation solution acquisition: Centrifuge the enzymatic reaction solution obtained in Step 1 at 8000 r / min for 15 min, and collect the supernatant rich in small molecule aromatic compounds, which is the laccase degradation solution.

[0070] Step 3: Loading peat with degradation solution: Take 5 mL of laccase degradation solution obtained in step 2 and mix it with 5 g of peat. Place it in a constant temperature shaker and shake at 25℃ and 200 r / min for 24 h to allow the degradation solution to fully adsorb and react, and obtain a modified peat-based soil conditioner.

[0071] The peat used in this embodiment is commercially available herbal peat, purchased from Ningbo Xiaorang Ecological Technology Co., Ltd., with an organic matter content ≥45%, humic acid content ≥30%, and pH (water extraction) of 5.5-6.5.

[0072] Soil improvement experiments were conducted using the modified peat-based soil conditioner prepared in this embodiment. Saline soil and vermiculite were mixed at a mass ratio of 1:2.5 to obtain a salinization simulation matrix. The saline soil used was the same as that in Example 1.

[0073] Add 5g of the modified peat-based soil conditioner prepared in this embodiment to 450g of salinization simulation matrix, mix well, and then put into a potted container. Use soybean as the test crop for cultivation experiments to evaluate the effect of this conditioner on crop growth and soil properties under salinity stress.

[0074] Example 6

[0075] The only difference between this embodiment and embodiment 5 is that in step three, loading peat with degradation solution: take 10 mL of laccase degradation solution obtained in step two and mix it with 5 g of peat, place it in a constant temperature shaker and shake it at 25°C and 200 r / min for 24 h to allow the degradation solution to be fully adsorbed and reacted, and obtain modified peat-based soil conditioner.

[0076] In the soil improvement experiment of this embodiment, 5g of the modified peat-based soil conditioner prepared in this embodiment was added to 450g of salinization simulation matrix.

[0077] Example 7

[0078] The only difference between this embodiment and embodiment 5 is that in step three, loading peat with degradation solution: take 25 mL of laccase degradation solution obtained in step two and mix it with 5 g of peat, place it in a constant temperature shaker and shake it at 25°C and 200 r / min for 24 h to allow the degradation solution to be fully adsorbed and reacted, and obtain modified peat-based soil conditioner.

[0079] In the soil improvement experiment of this embodiment, 5g of the modified peat-based soil conditioner prepared in this embodiment was added to 450g of salinization simulation matrix.

[0080] Example 8

[0081] The only difference between this embodiment and embodiment 5 is that in step three, loading peat with degradation solution: take 60 mL of laccase degradation solution obtained in step two and mix it with 5 g of peat, place it in a constant temperature shaker and shake it at 25 °C and 200 r / min for 24 h to allow the degradation solution to be fully adsorbed and reacted, and obtain modified peat-based soil conditioner.

[0082] In the soil improvement experiment of this embodiment, 5g of the modified peat-based soil conditioner prepared in this embodiment was added to 450g of salinization simulation matrix.

[0083] Example 9

[0084] The only difference between this embodiment and embodiment 5 is that in step three, loading peat with degradation solution: take 15 mL of laccase degradation solution obtained in step two and mix it with 5 g of peat, place it in a constant temperature shaker and shake it at 25°C and 200 r / min for 24 h to allow the degradation solution to be fully adsorbed and reacted, and obtain modified peat-based soil conditioner.

[0085] Example 10

[0086] The only difference between this embodiment and embodiment 5 is that in step three, loading peat with degradation solution: take 30 mL of laccase degradation solution obtained in step two and mix it with 5 g of peat, place it in a constant temperature shaker and shake it at 25 °C and 200 r / min for 24 h to allow the degradation solution to be fully adsorbed and reacted, and obtain modified peat-based soil conditioner.

[0087] Example 11

[0088] The only difference between this embodiment and embodiment 5 is that in step three, loading peat with degradation solution: take 45 mL of laccase degradation solution obtained in step two and mix it with 5 g of peat, place it in a constant temperature shaker and shake it at 25°C and 200 r / min for 24 h to allow the degradation solution to be fully adsorbed and reacted, and obtain modified peat-based soil conditioner.

[0089] Example 12

[0090] The only difference between this embodiment and embodiment 5 is that in step three, loading peat with degradation solution: take 75 mL of laccase degradation solution obtained in step two and mix it with 5 g of peat, place it in a constant temperature shaker and shake it at 25 °C and 200 r / min for 24 h to allow the degradation solution to be fully adsorbed and reacted, and obtain modified peat-based soil conditioner.

[0091] Example 13

[0092] This embodiment provides a modified peat-based soil conditioner based on laccase-degraded lignin products, which is prepared through the following steps:

[0093] Step 1: Enzymatic hydrolysis and liquefaction of lignin: Take 0.5g of lignin raw material, add 100mL of citric acid-sodium citrate buffer solution with pH 5.0, stir and mix well, then add 2.5g of laccase with an enzyme activity of 10000U / kg and 0.1g of eugenol, and carry out the enzymatic hydrolysis reaction for 30h under constant temperature shaking at 50℃ to obtain the enzymatic hydrolysis reaction solution.

[0094] Step 2, solid-liquid separation and degradation solution acquisition: Centrifuge the enzymatic reaction solution obtained in Step 1 at 8000 r / min for 15 min, and collect the supernatant rich in small molecule aromatic compounds, which is the laccase degradation solution.

[0095] Step 3: Loading peat with degradation solution: Take 15 mL of laccase degradation solution obtained in step 2 and mix it with 5 g of peat. Place the mixture in a constant temperature shaker and shake at 25℃ and 200 r / min for 24 h to allow the degradation solution to fully adsorb and react, thus obtaining a modified peat-based soil conditioner.

[0096] The peat used in this embodiment is commercially available herbal peat, purchased from Ningbo Xiaorang Ecological Technology Co., Ltd., with an organic matter content ≥45%, humic acid content ≥30%, and pH (water extraction) of 5.5-6.5.

[0097] Example 14

[0098] This embodiment provides a modified peat-based soil conditioner based on laccase-degraded lignin products, which is prepared through the following steps:

[0099] Step 1: Enzymatic hydrolysis and liquefaction of lignin: Take 0.5g of lignin raw material, add 100mL of citric acid-sodium citrate buffer solution with pH 5.0, stir and mix well, then add 12.5g of laccase with an enzyme activity of 10000U / kg and 0.1g of eugenol, and carry out the enzymatic hydrolysis reaction for 30h under constant temperature shaking at 50℃ to obtain the enzymatic hydrolysis reaction solution.

[0100] Step 2, solid-liquid separation and degradation solution acquisition: Centrifuge the enzymatic reaction solution obtained in Step 1 at 8000 r / min for 15 min, and collect the supernatant rich in small molecule aromatic compounds, which is the laccase degradation solution.

[0101] Step 3: Loading peat with degradation solution: Take 15 mL of laccase degradation solution obtained in step 2 and mix it with 5 g of peat. Place the mixture in a constant temperature shaker and shake at 25℃ and 200 r / min for 24 h to allow the degradation solution to fully adsorb and react, thus obtaining a modified peat-based soil conditioner.

[0102] The peat used in this embodiment is commercially available herbal peat, purchased from Ningbo Xiaorang Ecological Technology Co., Ltd., with an organic matter content ≥45%, humic acid content ≥30%, and pH (water extraction) of 5.5-6.5.

[0103] Comparative Example 1

[0104] This comparative example uses a salinization simulation substrate as a control experiment for soil improvement. The salinization simulation substrate was prepared by mixing saline soil and vermiculite at a mass ratio of 1:2.5. The saline soil used was the same as that in Example 1. 450g of the salinization simulation substrate was placed in a potted container, and soybean was used as the test crop for cultivation experiments.

[0105] Comparative Example 2

[0106] This comparative experiment used a salinization simulation substrate and unmodified peat as controls for soil improvement. A salinization simulation substrate was obtained by mixing saline soil and vermiculite at a mass ratio of 1:2.5; the saline soil used was the same as in Example 1. 450g of the salinization simulation substrate and 5g of peat were mixed thoroughly and placed in potted containers. Soybeans were used as the test crop for cultivation experiments.

[0107] The peat used in this comparative example was commercially available herbal peat, purchased from Ningbo Xiaorang Ecological Technology Co., Ltd., with an organic matter content ≥45%, humic acid content ≥30%, and pH (water extraction) of 5.5–6.5.

[0108] Experimental Example 1

[0109] This experimental example is an analysis of functional group changes in the synergistic degradation of lignin by laccase and eugenol.

[0110] I. Fourier transform infrared spectroscopy was used to characterize and analyze the effects of buffer solution, laccase (LAC), and eugenol on the chemical structure of lignin, as well as the synergistic effect of laccase and eugenol, to elucidate the mechanism of molecular structure change in lignin through oxidative modification by the laccase / eugenol mediator system.

[0111] Five parallel reaction systems were set up, all using the same buffer solution as the reaction medium:

[0112] (1) Pure buffer solution group: 100 mL of citrate-sodium citrate buffer solution with pH 5.0, let stand at room temperature for 30 h;

[0113] (2) Buffer + lignin group: Take 0.5g of lignin raw material, add 100mL of citric acid-sodium citrate buffer solution with pH 5.0, and react for 30h under constant temperature shaking at 50℃;

[0114] (3) Buffer solution + lignin + eugenol group: Take 0.5g of lignin raw material, add 100mL of citric acid-sodium citrate buffer solution with pH 5.0, stir and mix well, then add 0.1g of eugenol, and react for 30h under constant temperature shaking at 50℃.

[0115] (4) Buffer + Lignin + Laccase LAC group: Take 0.5g of lignin raw material, add 100mL of citrate-sodium citrate buffer solution with pH 5.0, stir and mix well, then add 12.5g of laccase with an enzyme activity of 10000U / kg, and enzymatically hydrolyze for 30h under constant temperature shaking at 50℃.

[0116] (5) Buffer + Lignin + Laccase LAC + Syringaldehyde group: Take 0.5g of lignin raw material, add 100mL of citrate-sodium citrate buffer solution with pH 5.0, stir and mix well, add 12.5g of laccase with an enzyme activity of 10000U / kg and 0.1g of syringaldehyde, and enzymatically hydrolyze for 30h under constant temperature shaking at 50℃.

[0117] After each group of reactions was completed, the reaction solution was centrifuged, washed, freeze-dried, and then subjected to infrared spectroscopy. Simultaneously, pure lignin powder was used as a control for infrared spectroscopy. The results are as follows: Figure 1 As shown, compared with pure lignin, the buffer + lignin system contains a large number of phenolic hydroxyl groups, benzene rings, and ether bonds, while the carboxyl content is extremely low. In the system with only eugenol added and no laccase, there is no significant consumption of various lignin skeletal functional groups, indicating that eugenol alone cannot trigger the oxidative degradation reaction of lignin. The laccase-only treatment system only consumes a small amount of phenolic hydroxyl groups and generates a small amount of quinone groups, resulting in a limited overall degree of oxidative modification. In the laccase + eugenol synergistic system, phenolic hydroxyl groups, benzene ring C=C, and ether bonds are significantly reduced, while carboxyl and quinone oxygen-containing functional groups are significantly increased. From the perspective of structural change effects, the consumption of phenolic hydroxyl groups, aromatic carbon-carbon double bonds, and ether bonds can destroy the original molecular cross-linking network of lignin, promoting the depolymerization of lignin macromolecules. On the other hand, the enrichment of carboxyl and quinone structures can improve the hydrophilicity of modified lignin, while increasing the number of surface active sites, effectively enhancing the material's adsorption performance for organic pollutants and its chelation ability for metal ions.

[0118] The above results confirm that eugenol itself does not have the ability to directly degrade lignin, but can only act as an oxidation mediator in the laccase catalytic system, relying on the synergistic effect of the two to complete the efficient oxidative modification of lignin.

[0119] 2. Weigh 1.0 g of lignin raw material and the remaining solid sample after laccase treatment in Example 5, and add 10 mL of deionized water for extraction to obtain water-soluble phenol extracts. Accurately transfer 1 mL of the extract to a colorimetric tube, and add 5 mL of 10% Folin-Ciocalteu reagent and 4 mL of 7.5% sodium carbonate solution sequentially. Mix thoroughly and develop the color. Zero the tube with a blank reagent and measure the absorbance of the solution at the corresponding wavelength. Calculate the phenol concentration in the colorimetric system based on the standard curve, and convert the extraction volume and colorimetric dilution factor to obtain the water-soluble phenol content in each sample, in mg / g.

[0120] The results are as follows Figure 2 As shown, the extractable phenol content of solid-phase lignin is significantly reduced after the laccase reaction, indicating that the laccase oxidation catalyzes the polymerization or depolymerization of lignin phenolic hydroxyl groups, releasing small molecule phenolic acids and organic acids into the liquid phase. After the supernatant of this reaction is mixed with peat, the active substances in the liquid phase can activate the insoluble phosphorus in the peat through complexation and ion exchange, thereby increasing the effective phosphorus level in the system, realizing the immobilization of degradation products, and synergistically optimizing the physicochemical properties of the matrix.

[0121] Third, using pure buffer solution as a blank reference, the transmittance of the supernatant obtained after centrifugation of the above five systems after reaction was determined by ultraviolet-visible spectrophotometry in the range of 200-450 nm. This characterizes the degree of lignin dissolution, degradation and molecular structure cleavage at the liquid phase level. Combined with the previous FTIR solid structure data, this bidirectionally confirms the oxidative depolymerization effect of the laccase + eugenol mediator system on lignin.

[0122] The results are as follows Figure 3 As shown, the buffer solution, lacking conjugated aromatic functional groups, exhibited the highest transmittance. The buffer solution + lignin group showed only a small amount of macromolecule dissolution, resulting in a slight decrease in transmittance. The lignin + syringaldehyde group showed no oxidation reaction, with almost no increase in small quinone molecules in the liquid phase, and its curve was similar to that of the lignin group. The laccase system alone showed a slight increase in conjugated functional groups in the liquid phase, leading to a slight decrease in transmittance. The laccase + syringaldehyde system exhibited significant breakage of the solid-phase aromatic structure, with a large amount of quinone and conjugated carboxyl groups dissolving into the liquid phase, resulting in the lowest transmittance. Analysis of the structural change effect revealed that the increase in quinone and aromatic carboxyl groups in the liquid phase generated characteristic ultraviolet absorption, reducing transmittance. These active functional groups can act as modifying agents to undergo coupled oxidation reactions with peat. The 250-350 nm wavelength range is the characteristic wavelength of aromatic conjugation, and the differences in functional group content among the groups showed the highest discriminative power.

[0123] IV. Five reaction systems were prepared according to the aforementioned experimental conditions. After each system completed the isothermal oxidation reaction, it was centrifuged at 8000 r / min for 15 min using a high-speed centrifuge. The solid precipitate was discarded, and the supernatant was collected. Two solid-liquid ratios were set up to conduct peat modification experiments:

[0124] (1) Solid-liquid mass ratio 1:6 group: Weigh 5g of natural peat raw material, take 30g of the lignin degradation supernatant of each group above, mix the peat and degradation liquid thoroughly and put them into a sealed reaction container; place the mixed system in a constant temperature shaking shaker, control the ambient temperature at 25℃ and the shaking speed at 200r / min, and continue shaking reaction for 24h.

[0125] (2) Solid-liquid mass ratio group 1:12: Weigh 5g of natural peat raw material and take 60g of the lignin degradation supernatant of each group above. Mix the peat and degradation liquid thoroughly and put them into a sealed reaction container. Place the mixed system on a constant temperature shaking table, control the ambient temperature at 25℃ and the shaking speed at 200r / min, and continue shaking for 24h.

[0126] After the solid-liquid coupling reactions of each group were completed, the mixture was centrifuged again to separate and collect the liquid phase solution. The collected liquid phase samples were then analyzed using a UV spectrophotometer with a scanning wavelength range of 250-450 nm. The transmittance changes of different samples were measured, and the results are as follows: Figure 4 As shown,

[0127] In the 350–375 nm long-wavelength range, the transmittance characteristics of the quinone conjugated substances in each group still showed significant differences. The laccase-free system had a low content of active oxygen-containing functional groups in the liquid phase and a higher overall transmittance. The laccase + syringaldehyde synergistic system had the lowest transmittance across the entire wavelength range, and the accumulation of quinone groups and aromatic carboxyl groups was significantly higher than that of the other experimental groups. The ultraviolet absorption signals of quinone conjugated functional groups could be accurately identified in the long-wavelength region, confirming that the laccase-syringaldehyde system can generate a large number of more water-soluble long-wavelength responsive oxygen-containing functional groups, which are more likely to participate in the peat solid-liquid coupling modification process. Using a wide-band scanning of 250–450 nm, all conjugated functional group signals generated by lignin oxidation could be completely detected. The data showed that the higher the degree of consumption of phenolic hydroxyl and benzene ring structures in the solid phase, the greater the amount of quinone and carboxyl groups generated in the liquid phase. A large number of polar oxygen-containing functional groups dissolved and remained in the degradation solution, providing sufficient active reaction substrates for peat modification. Comparing the 1:6 and 1:12 solid-liquid systems, the 1:6 system was limited by the total amount of active substances in the liquid phase, resulting in insufficient peat modification reaction; the 1:12 system had a sufficient substrate supply, allowing active small molecules to fully bind to the pores and surface sites of the peat, and the coupling modification reaction proceeded more thoroughly.

[0128] Experimental Example 2

[0129] This experiment investigated the structural changes of lignin solid-phase deconstruction and liquid-phase dissolution of active components under the synergistic effect of laccase and eugenol.

[0130] I. Characterization was performed using Fourier transform infrared spectroscopy. The solid residues obtained in step two of T1 (Example 1: 2.5g laccase + 0.01g syringaldehyde), T2 (Example 13: 2.5g laccase + 0.1g syringaldehyde), T3 (Example 5: 12.5g laccase + 0.01g syringaldehyde), and T4 (Example 14: 12.5g laccase + 0.1g syringaldehyde) were analyzed by infrared spectroscopy. The original lignin powder (CK) was used as a control. The results are as follows: Figure 5As shown, the CK original lignin exhibits the highest absorption peak intensity at OH, C=C of the benzene ring, and the CO ether bond, while the absorption of carboxyl and quinone groups is weak. With the same laccase dosage, increasing the syringaldehyde dosage leads to a continuous decrease in phenolic hydroxyl groups and aromatic bonds, while carboxyl and quinone groups accumulate. With the same syringaldehyde dosage, increasing the laccase dosage further deepens the lignin oxidation and degradation. T4 (high laccase + high syringaldehyde) shows the greatest degree of lignin skeleton destruction, while T1 (low laccase + low syringaldehyde) shows the smallest change in functional groups. From the perspective of structural change effects: lignin originally relies on ether bonds and phenolic hydroxyl groups to form a dense macromolecular network skeleton. During the reaction, phenolic hydroxyl groups and ether bonds are continuously consumed and broken, causing the originally large lignin molecules to be disassembled and broken down. At the same time, the content of carboxyl and quinone groups in the system continues to increase. On the one hand, this makes the hydrophilicity of solid lignin better, enabling it to fix more heavy metal ions through adsorption and chelation. On the other hand, these hydrophilic oxygen-containing groups are more soluble in water, allowing the broken lignin molecules to detach from the solid residue and dissolve in the supernatant.

[0131] II. The supernatants obtained in step two of T1 (Example 1), T2 (Example 13), T3 (Example 5), and T4 (Example 14) were subjected to ultraviolet-visible spectral scanning. The results are as follows: Figure 6 As shown, the original lignin in the CK group showed no catalytic reaction, had few conjugated aromatic functional groups in the liquid phase, and exhibited the highest transmittance across all wavelengths. Under the same laccase conditions, the transmittance of the high-syringaldehyde groups T2 and T4 was lower than that of the low-syringaldehyde groups T1 and T3. Under the same syringaldehyde conditions, the transmittance of the high-laccase groups T3 and T4 was lower than that of the low-laccase groups T1 and T2. The T4 system had the highest content of quinone groups and conjugated carboxyl groups in the liquid phase, and the lowest transmittance. The differences in transmittance among the groups were most significant in the 250-350nm wavelength range. Analysis of the structural change effect: the reduced consumption of phenolic hydroxyl groups and aromatic structures in the solid phase indicates continuous depolymerization and dissolution of lignin; the increased content of quinone groups and conjugated carboxyl groups in the liquid phase results in strong ultraviolet conjugated absorption, and the liquid phase products possess oxidative activity, allowing for coupling modification with the peat matrix.

[0132] Experimental Example 3

[0133] This experiment investigated the effects of lignin hydrolysate dosage on peat functional group modification and retention of active substances in the liquid phase.

[0134] Fourier transform infrared spectroscopy was used for characterization. The differences in characteristic absorption peaks of hydroxyl groups, C-H bonds, C-C double bonds, carboxyl groups, and silicon-oxygen bonds of PEAT unmodified peat were compared between six groups of modified peat samples: P1 (Example 5: 5g peat + 5mL enzymatic hydrolysate), P2 (Example 9: 5g peat + 15mL enzymatic hydrolysate), P3 (Example 10: 5g peat + 30mL enzymatic hydrolysate), P4 (Example 11: 5g peat + 45mL enzymatic hydrolysate), P5 (Example 8: 5g peat + 60mL enzymatic hydrolysate), and P6 (Example 12: 5g peat + 75mL enzymatic hydrolysate). The effect of different amounts of enzymatic hydrolysate on the modification effect of peat chemical structure was analyzed.

[0135] The results are as follows Figure 7 As shown, the catalytic solution is rich in carboxyl and quinone groups, which undergo coupled oxidation when mixed with peat. At a solid-liquid ratio of 1:1, the peat content is high, resulting in less loss of OH groups and aromatic C=C bonds in the peat itself, and a low number of newly added carboxyl and quinone groups in the solid phase. As the solid-liquid ratio increases to 1:15, the liquid phase proportion continuously increases, the phenolic hydroxyl groups and aromatic double bonds on the peat surface decrease, and a large number of carboxyl and quinone groups combine with the peat framework, significantly increasing the total oxygen-containing acidic functional groups in the solid phase. The reduction in the original phenolic hydroxyl groups and aromatic bonds in the peat indicates that the peat has been oxidized and modified by the lignin degradation solution. The increase in carboxyl and quinone groups significantly improves the cation exchange capacity, hydrophilicity, and heavy metal adsorption capacity of the peat, with the 1:15 ratio showing the best peat modification effect.

[0136] The supernatant obtained in step two of P1 (Example 5), P2 (Example 9), P3 (Example 10), P4 (Example 11), P5 (Example 8), and P6 (Example 12) and the modified peat were subjected to UV-Vis spectroscopy. The results are as follows: Figure 8 As shown, the core substances for liquid-phase color development are quinone and conjugated aromatic carboxyl small molecules. The 1:1 solid-liquid ratio results in the highest peat content, with a large number of oxygen-containing conjugated functional groups in the liquid phase being adsorbed and fixed by the peat, reducing the amount of light-absorbing material and achieving the highest transmittance. As the solid-liquid ratio increases, the relative proportion of peat decreases, leading to insufficient adsorption capacity. Quinone and aromatic carboxyl groups accumulate in the liquid phase, gradually reducing the transmittance. The 1:15 ratio shows the lowest peat content, the most residual conjugated functional groups in the liquid phase, and the lowest transmittance. Analysis of the structural change effect reveals that the reduction in quinone and carboxyl groups adsorbed by peat in the liquid phase can decrease the content of colored organic matter in the water. Even after peat adsorption saturation, the remaining oxygen-containing functional groups in the liquid phase still possess oxidative activity and can continue to be used for soil improvement and pollutant fixation.

[0137] Test Example 4

[0138] This experimental example reveals the characteristics of how laccase, in conjunction with eugenol, activates inert phosphorus in peat and increases the available phosphorus content under different temperature conditions.

[0139] Four reaction systems were set up, all using a pH 5.0 citric acid-sodium citrate buffer solution as the reaction medium. Experiments were conducted at four temperatures: 15℃, 25℃, 35℃, and 45℃. Each system used 5g of raw peat sample, and the reaction was carried out under constant temperature and shaking for 30 hours.

[0140] (1) Pure peat blank group: Weigh 5g of natural peat, without adding any reaction solution, and place it in the corresponding temperature environment for 30h;

[0141] (2) Pure buffer solution group: Weigh 5g of natural peat, add 100mL of citric acid-sodium citrate buffer solution with pH 5.0, and react at constant temperature and shaking for 30h at 15℃, 25℃, 35℃ and 45℃ respectively;

[0142] (3) Buffer solution + lignin group: Weigh 5g of natural peat and 0.5g of lignin raw material, add 100mL of citric acid-sodium citrate buffer solution with pH 5.0, and react at constant temperature and shake for 30h at 15℃, 25℃, 35℃ and 45℃ respectively.

[0143] (4) Buffer solution + lignin + eugenol + laccase group: Weigh 5g of natural peat, 0.5g of lignin, 0.01g of eugenol and 12.5g of laccase with an enzyme activity of 10000U / kg, mix them into 100mL of citrate-sodium citrate buffer solution with pH 5.0, and react them at constant temperature and shaking for 30h at 15℃, 25℃, 35℃ and 45℃ respectively.

[0144] After the reactions in each group were completed, solid-liquid separation was performed, and solid peat samples were collected. After air drying, grinding, and sieving, the available phosphorus components of the peat were extracted using a double acid extraction method. The available phosphorus content of each sample was determined by spectrophotometry. The results are as follows: Figure 9 As shown, eugenol acts as a redox mediator, broadening the catalytic oxidation range of laccase and precisely breaking the β-O-4 ether bonds in the lignin macromolecular structure. This degrades insoluble polymeric lignin into water-soluble, highly active small molecules carrying numerous carboxyl and phenolic hydroxyl groups, which are then enriched and retained in the enzymatic hydrolysis supernatant. After mixing this supernatant with peat, the small-molecule active substances can penetrate into the microporous structure of the peat, capturing iron and aluminum metal ions bound to phosphate through coordination chelation. This weakens the binding force between metal ions and phosphate, allowing the inert phosphorus sealed in the peat to be converted into dissociable active phosphorus. Double acid extraction analysis shows a significant increase in the effective phosphorus content of the peat. The entire activation process follows a stepwise reaction mechanism of enzymatic hydrolysis—mediated activation—complexation release—acid extraction enhancement. It relies on the chelating properties of lignin degradation products to break the metal-bound binding of phosphorus, ultimately achieving efficient activation of the endogenous inert phosphorus in the peat.

[0145] Experimental Example 5

[0146] This experiment investigated the promoting effect of modified peat-based soil conditioner on soybean seedling growth and biomass accumulation.

[0147] I. Pot experiments were conducted on Comparative Example 1 (no soil conditioner CK), Comparative Example 2 (only unmodified peat CK-P), and Examples 1-8 (each with different modified peat-based soil conditioners). On the 21st day after planting, the overall root morphology of soybean seedlings in each group was as follows: Figure 10 As shown, the above-ground growth of a potted soybean plant is viewed from above. Figure 11 As shown, the side view of the overall growth of the soybean potted plant is as follows. Figure 12 As shown, the CK and CK-P groups had fewer roots and sparse fibrous roots, resulting in shorter stems and leaves and weaker overall growth. In contrast, all groups from Example 1 to Example 8 showed more developed root systems, increased number of fibrous roots, denser root arrangement, more leaves in potted plants, darker green leaves, and significantly increased plant height.

[0148] II. The lengths of the aboveground and underground parts of soybean seedlings in each treatment group were measured, and the results are as follows: Figure 13 As shown, the aboveground plant height of CK-P was significantly lower than that of CK group. The original peat could not supply effective phosphorus nutrients and would also slightly inhibit the elongation of seedlings. All modified peat treatment groups could increase the length of the aboveground and underground parts of soybeans. Among them, the aboveground plant height of Example 7 reached the maximum value of all groups, and the underground root length was the best in Example 2.

[0149] III. The fresh weight of the aboveground and underground parts of soybean seedlings in each treatment group was weighed, and the results are as follows: Figure 14 As shown, the dry weight of the aboveground and underground parts of soybean seedlings in each treatment group was weighed, and the results are as follows. Figure 15 As shown, the patterns of plant fresh weight and dry weight were consistent with the apparent growth: the overall aboveground and belowground fresh and dry weights of the CK and CK-P groups were at a relatively low level. After the modified peat-based soil conditioner in Examples 1-8 was filled into the soil, the activated available phosphorus inside the peat could be absorbed and utilized by the crop roots, promoting the accumulation of plant biomass. The fresh and dry weights of each group increased significantly compared with the control group. Example 1 had the highest aboveground dry weight, while Example 8 showed the best effect in underground dry weight accumulation. There were no significant differences in aboveground and underground biomass indicators among most modified groups, indicating that modified peat with different solid-liquid ratios can stably improve soil fertility and supply phosphorus nutrition.

[0150] Overall, the peat amendment modified with lignin enzymatic hydrolysate enhances the available phosphorus supply in the soil by activating endogenous inert phosphorus, which promotes the germination and elongation of soybean roots, strengthens root absorption capacity, and promotes the growth of aboveground stems and leaves and the accumulation of dry matter, thus achieving a comprehensive improvement in the growth of soybean seedlings.

[0151] Experimental Example 6

[0152] This experiment investigated the regulatory effect of modified peat-based soil conditioner on soybean root architecture.

[0153] Pot experiments were conducted on Comparative Example 1 (no amendment CK), Comparative Example 2 (only unmodified peat CK-P), and Examples 1-8 (with different modified peat-based soil conditioners). On the 21st day after planting, soybean roots in each treatment group were scanned and analyzed to measure root length, root surface area, root volume, and root tip number. Root morphology photographs and morphological index results are shown below. Figure 16 As shown in Table 1.

[0154] Table 1

[0155]

[0156] like Figure 16 As shown in Table 1, the roots of the CK and CK-P groups were thin and sparsely branched, with root lengths of only 631.49 cm and 649.6 cm, respectively, and root tip numbers of 113.33 and 133.33, respectively. In contrast, the root length, volume, surface area, and root tip number of the Example 1 to Example 8 groups were significantly increased. The root length of Example 8 reached 1166.68 cm, and the root tip number of Example 6 was as high as 300.33. The growth advantages of the Example 5, Example 6, and Example 8 treatments were particularly prominent, indicating that this series of treatments had a significant promoting effect on soybean root morphology construction and underground growth.

[0157] Experimental Example 7

[0158] This experiment investigated the effect of a modified peat-based soil conditioner on the chlorophyll content of soybean leaves.

[0159] Pot experiments were conducted on Comparative Example 1 (no amendment CK), Comparative Example 2 (only unmodified peat CK-P), and Examples 1-8 (with different modified peat-based soil conditioners). On the 21st day after planting, the chlorophyll content of soybean functional leaves in each treatment group was measured using a handheld chlorophyll meter. The results are as follows: Figure 17 As shown, among the 10 treatments, the chlorophyll value of treatment 8 increased significantly, with an increase of 27.3% compared to the CK treatment. The chlorophyll values ​​of treatments 1, 2, 3, 4, 5, and 6 also increased compared to CK and CK-P, but did not reach a significant level. The chlorophyll values ​​of all treatments 1-8 were not lower than those of the CK and CK-P treatments, indicating that the modified peat-based soil conditioner prepared in examples 1-8 can effectively alleviate the degradation effect of salt-alkali stress on soybean leaf chlorophyll and maintain the stability of the plant's photosynthetic system.

[0160] Experimental Example 8

[0161] This experiment investigated the effect of modified peat-based soil conditioner on regulating the content of available phosphorus in soil.

[0162] Pot experiments were conducted on Comparative Example 1 (no soil conditioner CK), Comparative Example 2 (only unmodified peat CK-P), and Examples 1-8 (each with different modified peat-based soil conditioners). On the 21st day after planting, soybean rhizosphere soil samples were collected from each treatment group. The available phosphorus content in the soil was determined using the molybdenum-antimony colorimetric method. The results are as follows: Figure 18 As shown.

[0163] Available phosphorus in soil is a form of phosphorus that can be directly absorbed and utilized by soybeans in saline-alkali environments, and its content directly determines the soil's phosphorus supply capacity. The available phosphorus content in the soil of the negative control CK-P was significantly higher than that of the blank control CK, indicating that peat itself contains a certain amount of phosphorus. Among the other treatments, the available phosphorus content in the soil of treatments in Examples 2, 3, 4, and 6 was the highest among all treatment groups, significantly higher than CK and CK-P; the available phosphorus content in the soil of treatments in Examples 1 and 5 was significantly higher than CK, but not significantly different from CK-P; the available phosphorus content in treatment in Example 7 was significantly higher than CK and significantly lower than CK-P.

[0164] In summary, the treatments in Examples 2, 3, 4, and 6 showed the best effect on improving available phosphorus in saline-alkali soils, effectively enhancing the phosphorus supply capacity of saline-alkali soils and alleviating phosphorus nutrient deficiency under saline-alkali stress.

[0165] Experimental Example 9

[0166] This experimental example investigated the effect of modified peat-based soil conditioner on Na+ in soybean plants. + and K + The effect of content regulation.

[0167] I. Pot experiments were conducted on Comparative Example 1 (no amendment CK), Comparative Example 2 (only unmodified peat CK-P), and Examples 1-8 (with different modified peat-based soil conditioners). On the 21st day after planting, soybean plant samples were collected from each treatment group, divided into aboveground and underground parts. Na+ was determined by atomic absorption spectrophotometry. + and K + Content, results as follows Figure 19 and Figure 20 As shown.

[0168] Na+ levels in the aboveground and underground parts of soybean under different treatments under salt-alkali stress + Accumulation varies. Aboveground Na... + Regarding content, only the treatments in Examples 1, 3, and 4 were significantly lower than the blank control (CK). The remaining examples showed no significant difference from CK, and all example groups showed no significant difference from the negative control (CK-P). (Underground Na) +Regarding the content, only the treatment in Example 1 was significantly lower than CK and CK-P, representing the lowest level among all treatment groups. All other example groups showed no significant difference from the two control groups. Overall, the modified peat-based soil conditioner can inhibit the absorption of Na+ by soybean roots in saline-alkali environments. + Absorption and reduction of Na + The transport of toxic ions to the above-ground photosynthetic organs reduces the accumulation of toxic ions in the plant and alleviates the ion toxicity caused by salt and alkali stress. Among them, the sodium reduction regulation effect of the treatment in Example 1 is the most prominent.

[0169] Under salt-alkali stress, different treatments had different effects on potassium levels in the aboveground and underground parts of soybean. + The regulatory effects of accumulation also vary. Aboveground K + Among the contents, only the treatments in Examples 3, 7, and 8 were significantly higher than the negative control CK-P, with the treatment in Example 7 showing the highest level across all treatment groups, and also significantly higher than the blank control CK; only the treatment in Example 1 was significantly lower than CK and CK-P, while the other examples showed no significant difference from the two control groups. (Underground part K) + Of the K+ content, only the treatments in Examples 2 and 7 were significantly higher than CK-P; only the treatment in Example 1 was significantly lower than CK, and the other examples showed no significant difference from CK and CK-P. The results indicate that, except for Example 1, all examples effectively maintained or enhanced the soybean plant's resistance to K+. + The absorption and enrichment capacity of K, among which the treatment in Example 7 showed the best comprehensive regulation effect, which could simultaneously and significantly improve the K of both the aboveground and underground parts. + Accumulation of potassium effectively optimizes potassium levels in plants under salt-alkali stress. + / Na + Balance, maintaining ion homeostasis and osmotic regulation capabilities.

[0170] II. Based on the above Na + and K + Content calculation of Na in the aboveground and underground parts of each treatment group + / K + The ratio, the result is as follows Figure 21 As shown.

[0171] Na + / K + The ratio is a core indicator for evaluating a plant's ability to adapt to saline-alkali stress; a lower ratio indicates a stronger ability to regulate ion homeostasis. Under saline-alkali stress, different treatments affect the Na+ content of soybean aboveground and underground parts. + / K + The regulatory effects of ratios differ. Aboveground Na + / K + In the ratios, only Example 1 was significantly higher than the blank control (CK), while Examples 3, 4, 7, and 8 were significantly lower than CK. The remaining treatments showed no significant difference from CK. (Underground Na)+ / K + In the ratios, Examples 1 and 7 were significantly lower than CK and the negative control CK-P, with Example 1 showing the lowest level across all treatment groups. Examples 4 and 6 were significantly higher than CK, while the remaining treatments showed no significant difference from the two control groups. Overall, Example 7 can simultaneously reduce NNa in both the aboveground and underground parts of soybean. + / K + The ratio and ion steady-state comprehensive regulation effect are optimal, and Example 1 has the most outstanding effect in alleviating root ion toxicity.

[0172] III. Based on the Na content of the aboveground and underground parts of the plant + Content Calculation of Na + Migration index (above-ground Na) + Content / Na in underground part + (content), results as follows Figure 22 As shown.

[0173] Under salt-alkali stress, different treatments affect the Na+ content of soybean plants. + The regulatory effects of transport indices differ. Na+ levels were observed in the blank control (CK) and the negative control (CK-P). + There was no significant difference in the transport index, among which the Na treated in Example 1... + The transport index was the highest among all treatment groups, significantly higher than CK and CK-P; Na treated in Examples 7, 8, and 5 + The transport indices were all higher than the two control groups, but not significantly different; Na treated in Examples 2, 3, and 6 + The transport index showed no significant difference from the two control groups; Na treated in Example 4 + The translocation index was the lowest among all treatment groups, with no significant difference compared to the two control groups. (This is in conjunction with plant Na...) + From the perspective of accumulated characteristics, the treatment in Example 1 can improve Na + The proportion of toxic ions transported from the roots to the above-ground parts is reduced, thus decreasing the accumulation of toxic ions in the roots and alleviating the damage to the roots caused by salt and alkali stress.

[0174] IV. Based on the aboveground and underground parts of the plant (K) + Content calculation K + Migration Index (Aboveground K) + Content / K in underground part + (content), results as follows Figure 23 As shown.

[0175] Under salt-alkali stress, different treatments have different effects on the potassium content of soybean plants. + The regulatory effects of the translocation index differ. The K-values ​​of CK and CK-P... + There was no significant difference in the transport index, among which K treated in Example 3... +The transport index was the highest in the entire treatment group, significantly higher than CK-P, but not significantly different from CK; the K in the treatments of Examples 4, 7, and 8 + The transport index was higher than that of the two control groups, but the difference was not statistically significant; K treated in Examples 1 and 2 + The transport index was the lowest in the entire treatment group, with no significant difference compared to the two control groups; K in the example + The transport index showed no significant difference from either of the two control groups. Overall, except for Examples 1 and 2, all examples maintained or improved K. + The efficiency of transport to the above-ground photosynthetic organs was improved, with the treatment in Example 3 showing the most significant improvement. This treatment effectively ensured the supply of potassium nutrients to the above-ground parts of soybeans under salt-alkali stress, and maintained the stable operation of the plant's photosynthetic physiology and ion homeostasis.

[0176] Experimental Example 10

[0177] This experimental case investigated the effect of modified peat-based soil conditioner on rhizosphere soil Na+. + The effect of content regulation.

[0178] Comparative Example 1 (no soil conditioner, CK), Comparative Example 2 (only unmodified peat, CK-P), and Examples 1-8 (each with different modified peat-based soil conditioners) were subjected to pot experiments. On the 21st day after planting, rhizosphere soil samples were collected from each treatment group, and soil Na+ was determined using atomic absorption spectrophotometry. + Content, results as follows Figure 24 As shown.

[0179] Soil Na + Soil Na+ is one of the toxic ions under salt and alkali stress, and its content directly reflects the effectiveness of soil improvement. + In terms of sodium content, there was no significant difference between the blank control (CK) and the negative control (CK-P). The treatment in Example 1 had the lowest sodium content among all groups and was significantly lower than the two control groups, showing the most significant reduction in sodium ions. Example 7 treated the soil for sodium... + The content was significantly lower than CK and not significantly different from CK-P. Except for Example 8, the other treatments were not significantly different from the two control groups. Example 8 had the highest content among all groups and was significantly higher than the two control groups.

[0180] Experimental Example 11

[0181] In this experiment, pot experiments were conducted on Comparative Example 1 (no soil conditioner CK), Comparative Example 2 (only unmodified peat CK-P), and Examples 1-8 (each with different modified peat-based soil conditioners). The results included soybean growth indices (plant height, root length, stem fresh weight, root fresh weight, stem dry weight, root dry weight), physiological indices (chlorophyll SPAD value), root architecture indices (total root length, average root diameter, root volume, root surface area, root projected area, number of root tips), and ion content indices (aboveground Na+). + Aboveground part K + , underground Na + Underground K + Soil indicators (soil Na) + Soil K + Pearson correlation analysis was performed on soil available phosphorus, and the results are as follows: Figure 25 As shown.

[0182] Correlation analysis showed that soil available phosphorus content was significantly positively correlated with total root length (r=0.85, p<0.01), root surface area (r=0.82, p<0.01), and root tip number (r=0.79, p<0.01), indicating that the activation of fixed phosphorus in peat by enzymatic hydrolysate effectively promoted the growth and development of soybean roots by increasing the available phosphorus content in the soil. Soil available phosphorus content was also significantly positively correlated with potassium content in the aboveground parts of the plant. + The content showed a significant positive correlation (r=0.76, p<0.05) with the Na content in the aboveground parts. + The content showed a significant negative correlation (r=-0.71, p<0.05), indicating that improved phosphorus nutrient levels help plants maintain K. + / Na + balance.

[0183] Total root length, root surface area, and number of root tips were significantly positively correlated with the aboveground dry weight of the plant (r=0.88, 0.84, 0.81, p<0.01) and the underground dry weight (r=0.86, 0.82, 0.79, p<0.01), indicating that improved root architecture was the direct cause of increased plant biomass accumulation. Total root length was also significantly positively correlated with soil Na+. + The content showed a significant negative correlation (r=-0.74, p<0.05), indicating that a well-developed root system helps reduce Na content in the rhizosphere soil. + The content may be related to the root system's absorption of Na. + It is related to absorption and transport.

[0184] Chlorophyll content was significantly positively correlated with soil available phosphorus content (r=0.78, p<0.05) and with aboveground Na+ content. + The content showed a significant negative correlation (r=-0.69, p<0.05), indicating that the increase in phosphorus nutrients and Na content was significantly negatively correlated.+ The mitigation of toxicity together ensures the stability of the leaf photosynthetic system.

[0185] Aboveground part K + Content and Na content in aboveground parts + The content showed a significant negative correlation (r=-0.72, p<0.05), and the underground K + Content and Na content in underground parts + The content also showed a significant negative correlation (r=-0.68, p<0.05), further confirming K. + / Na + The central role of balance in adaptation to saline-alkali stress. Aboveground Na+ + Content and soil Na + The content showed a significant positive correlation (r=0.83, p<0.01), while the aboveground Na content in the example was significantly higher. + The content was the lowest among all treatment groups, and it was lower than that of soil Na. + The consistent content indicates a reduction in soil Na + The content is to reduce the Na content in plants. + The fundamental way to accumulate knowledge.

[0186] In summary, the correlation analysis results show that the modified peat-based soil conditioner prepared in each embodiment of the present invention increases the content of available phosphorus in the soil by activating fixed phosphorus in peat, thereby promoting soybean root morphology and aboveground biomass accumulation; at the same time, it reduces rhizosphere soil Na+ through the cation exchange effect of modified peat. + The content reduced the plant's reliance on Na. + The absorption and maintenance of K + / Na + The balance and synergy ultimately led to a significant improvement in plant growth.

Claims

1. A method for preparing a modified peat-based soil conditioner based on laccase-degraded lignin products, characterized in that, Includes the following steps: Step 1: Mix the lignin raw material with an acidic buffer solution with a pH of 4.5-5.5, add laccase and eugenol, and perform enzymatic hydrolysis at 45-55℃ for 20-40 hours to obtain the enzymatic hydrolysis reaction solution. Step 2: Separate the enzymatic hydrolysis reaction solution obtained in Step 1 into solid and liquid phases, and collect the supernatant, which is the laccase degradation solution. Step 3: Mix the laccase degradation solution obtained in Step 2 with peat at a volume-to-mass ratio of 1 mL:1 g to 15 mL:1 g, and shake to ensure that the degradation solution and peat are in full contact and react, thereby obtaining a modified peat-based soil conditioner.

2. The preparation method according to claim 1, characterized in that, In step one, the mass ratio of laccase to lignin raw material is 5-25:1, and the mass ratio of eugenol to lignin raw material is 0.02-0.2:

1.

3. The preparation method according to claim 2, characterized in that, In step one, the mass ratio of laccase to lignin raw material is 25:1, and the mass ratio of eugenol to lignin raw material is 0.2:

1.

4. The preparation method according to claim 3, characterized in that, The volume-to-mass ratio of the laccase degradation solution to peat in step three is 15 mL: 1 g.

5. The preparation method according to any one of claims 1-4, characterized in that, The acidic buffer solution mentioned in step one is a citric acid-sodium citrate buffer solution with a pH of 5.

0.

6. The preparation method according to claim 5, characterized in that, The enzymatic hydrolysis reaction described in step one takes 30 hours.

7. The preparation method according to claim 6, characterized in that, The oscillation temperature in step three is 20~30℃, and the oscillation time is 20~26 hours.

8. A modified peat-based soil conditioner, characterized in that, It is prepared by any one of the preparation methods described in claims 1-7.

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