Saline-alkali tolerant plant endophyte extract-charcoal-based soil conditioner and preparation method thereof

Abstract

The invention provides a saline-alkaline tolerant plant endophyte extract-charcoal-based soil conditioner and a preparation method thereof. Comprising the following components in parts by weight: 10-30 parts of a saline-alkaline tolerant plant endophyte fermentation product, 40-70 parts of straw charcoal, 5-15 parts of an amino acid chelate, 1-10 parts of a betaine compatible solute, 2-5 parts of bentonite, 2-5 parts of zeolite powder and 1.5-3 parts of an auxiliary material. The preparation method comprises the following steps: culture and fermentation of saline-alkaline tolerant plant endophytes, extraction of endophyte metabolites, preparation and activation of straw biochar, compounding of functional components, functionalization of biochar, component mixing, granulation and molding, drying and screening, curing and stabilization and the like. The special salt-tolerant mechanism of the salt-tolerant and alkali-tolerant plant endophyte is combined with the efficient adsorption characteristic of the biochar, the loading rate of functional substances is increased by using vacuum negative pressure impregnation and microwave-assisted permeation technologies, and the dual functions of salt adsorption and microbial activity are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural soil improvement, and in particular to a soil improver utilizing the synergistic effects of salt-alkali tolerant plant endophytes and biochar and a preparation method thereof, which is particularly suitable for the rapid improvement of saline-alkali land such as farmland in the Songnen Plain. Background Art

[0002] Soil salinization is a major challenge facing global agriculture. According to statistics, approximately 950 million hectares of land worldwide are affected by varying degrees of salinization, with over 100 million hectares of saline-alkali land in my country, severely restricting agricultural production and food security. High salt concentrations and high pH values ​​in saline-alkali soils exert multiple stresses on plant growth, including osmotic stress, ion toxicity, and nutrient imbalances, leading to reduced crop yields and even the inability to plant crops. Therefore, developing efficient, environmentally friendly, and cost-effective saline-alkali soil amelioration technologies is of great theoretical and practical significance.

[0003] Currently, saline-alkali soil improvement primarily involves physical, chemical, and biological methods. Physical improvement, including deep plowing and irrigation, can temporarily reduce surface soil salinity, but is complex, energy-intensive, and often has short-term effects. Chemical improvement, such as gypsum treatment, is effective but also expensive and prone to secondary pollution. Biological improvement, such as planting salt-tolerant plants and applying microbial technology, is environmentally friendly, but its effectiveness is limited and its stability is poor when used alone.

[0004] In recent years, biochar has garnered widespread attention as a novel soil improvement material. U.S. Patent No. 9809502B2, "Enhanced Biochar," discloses a biochar treated to enhance soil health by manipulating its physicochemical properties, such as bulk density, impregnation capacity, particle size distribution, surface area, and porosity. However, this technology primarily focuses on optimizing the biochar's properties, without considering its potential for synergistic interactions with microorganisms.

[0005] Chinese patent CN119605395A discloses a method for improving the soil of an edible fungus cultivation base, which specifically includes the following steps: S1. laying peat soil; S2. spreading biochar; S3. spreading fermentation liquid; S4. laying rice straw or wheat straw; S5. evenly spreading additives; S6 multi-point application. However, this technology does not have salt-alkali tolerance and has poor activity and stability in high-salt environments.

[0006] Chinese patent CN117903811B discloses a soil conditioner for desertified vegetation and its preparation method, describing a soil improvement composition containing biochar and a composite bacterial agent. However, this technology is not designed for the special environment of saline-alkali soil and lacks the support of osmotic regulating substances, resulting in a low survival rate of microorganisms under salt stress.

[0007] Chinese patent CN106077073A discloses a method for improving coastal saline-alkali soil with a composite agent. The composite agent is prepared by extracting humic acid from landfill leachate and mixed with saline-alkali soil. However, the special salt-tolerance mechanism of salt-alkali-tolerant plant endophytes is not utilized, resulting in limited improvement effects.

[0008] In addition, the following problems generally exist in the prior art:

[0009] 1. The special salt tolerance mechanisms of salt-tolerant plant endophytes have not been fully utilized, such as the ability to secrete compatible solutes such as betaine to reduce osmotic stress;

[0010] 2. During the process of biochar and microorganism compounding, there is a lack of effective microbial colonization and functional substance protection technology, resulting in unstable actual application effects;

[0011] 3. It is difficult to balance nutrient release and salt adsorption, and the improvement effect is not sustainable enough;

[0012] 4. The preparation process has high energy consumption, low efficiency and difficulty in cost control.

[0013] Therefore, there is an urgent need to develop a composite soil conditioner that integrates the special salt-tolerance mechanism of salt- and alkali-tolerant plant endophytes, the efficient salt adsorption and fixation capacity of biochar, and the support of osmotic regulating substances to achieve efficient and lasting improvement of saline-alkali soils. Summary of the Invention

[0014] In view of the problems existing in the prior art, the purpose of the present invention is to provide a salt-alkali tolerant plant endophyte extract-biochar-based soil conditioner and a preparation method thereof, so as to solve the following technical problems:

[0015] 1. How to fully utilize the special salt-tolerance mechanism of salt- and alkali-tolerant plant endophytes to improve the stability and effectiveness of amendments in high-salt environments;

[0016] 2. How to achieve synergistic effects between biochar and endophytic metabolites to improve salt adsorption capacity and maintain microbial activity;

[0017] 3. How to optimize the preparation process, improve product quality stability, and reduce energy consumption and production costs;

[0018] 4. How to achieve rapid and effective improvement of products in saline-alkali lands such as farmland in the Songnen Plain to increase crop yields.

[0019] To solve the above technical problems, the present invention provides a salt-alkali tolerant plant endophyte extract-biochar-based soil conditioner, comprising the following components:

[0020] 10-30 parts by weight of a fermentation product of salt-alkali-tolerant plant endophytes;

[0021] 40-70 parts by weight of straw biochar;

[0022] 5-15 parts by weight of amino acid chelate;

[0023] 1-10 parts by weight of a betaine-compatible solute;

[0024] 2-5 parts by weight of bentonite;

[0025] 2-5 parts by weight of zeolite powder;

[0026] Auxiliary materials 1.5-3 parts by weight.

[0027] The salt-alkali-tolerant plant endophyte fermentation product is obtained by fermenting at least one endophyte selected from Sphingomonas prati, Bacillus flexus, and Staphylococcus sp. These endophytes are isolated from salt-alkali-tolerant plants and have the ability to grow in high-salt environments and produce special metabolites, such as ACC deaminase, indole-3-acetic acid (IAA), and betaine, which can effectively alleviate salt stress in plants.

[0028] The specific surface area of ​​the straw biochar is 200-600m 2 / g, a porosity of 50-80%, and a pH of 7.0-9.0. By precisely controlling the pyrolysis temperature and activation conditions, the biochar has an appropriate microporous structure and surface properties, which are conducive to salt adsorption and microbial colonization.

[0029] The amino acid chelate contains at least two of glycine, glutamic acid, and lysine, with a total amino acid content of ≥40%. The amino acid chelate can form coordination compounds with common cations in saline-alkali soils, such as Na+ and Ca2+, to reduce the effective concentration of these ions and alleviate salt damage.

[0030] The auxiliary materials include 0.5-1 parts by weight of citric acid, 0.5-1 parts by weight of sodium alginate and 0.5-1 parts by weight of lignin sulfonate, which respectively play the roles of pH adjustment, physical structure stabilization and dispersion.

[0031] The present invention also provides a method for preparing the salt-alkali tolerant plant endophyte extract-biochar-based soil conditioner, comprising the following steps:

[0032] (1) Cultivation of salt-alkali tolerant plant endophytes: isolate and screen salt-alkali tolerant endophytes from salt-alkali tolerant plants, culture them in a medium containing 3-5% NaCl at 28-37°C for 18-48 hours, and collect the cells by centrifugation;

[0033] (2) Endophytic fermentation and metabolite extraction: The bacterial cells obtained in step (1) are inoculated into a fermentation medium, and fermented for 18-48 hours under the conditions of a temperature of 28-37°C, a pH of 6.5-7.5, and a dissolved oxygen content of 20-50%. The fermentation broth is collected by centrifugation and concentrated to 1 / 5 of the original volume, precipitated with ethanol, and the precipitate is collected and freeze-dried to obtain an endophytic metabolite extract;

[0034] (3) Preparation of straw biochar: crush the straw to 5-10 mm, pyrolyze at 500-600 °C for 1-2 hours under nitrogen protection, and cool to room temperature to obtain straw biochar;

[0035] (4) Biochar activation: The biochar obtained in step (3) was soaked in 1-2 mol / L KOH solution or 5-10% H3PO4 solution at a solid-liquid ratio of 1:5 (w / v) for 24 hours, washed to neutrality, and dried at 105±5°C to obtain activated biochar;

[0036] (5) functional component compounding: mixing the endophyte metabolite extract obtained in step (2) with amino acids and betaine, reacting at 40-50° C. for 2-3 hours to obtain a functional compound solution;

[0037] (6) Biochar functionalization: The activated biochar obtained in step (4) was mixed with the functional composite solution obtained in step (5) at a ratio of 1:3-1:5 (w / v) under a vacuum condition of -0.08 to -0.09 MPa and immersed for 2-4 hours, subjected to microwave-assisted infiltration treatment for 5-10 minutes, and dried at 50-60° C. to obtain functionalized biochar;

[0038] (7) Component mixing: mixing the functionalized biochar obtained in step (6) with bentonite, zeolite powder and auxiliary materials, and stirring evenly;

[0039] (8) Granulation: The mixture obtained in step (7) was adjusted to have a moisture content of 18-22%, 3-5% sodium alginate solution was added as a binder, and granulated using a rotary drum granulator to control the particle size to 2-4 mm;

[0040] (9) Drying and sieving: The granules obtained in step (8) are dried in a multi-layer belt dryer according to a temperature profile of preheating at 40-50°C for 30-60 minutes, main drying at 55-58°C for 60-90 minutes, and constant temperature drying at 50-55°C for 30-60 minutes to a moisture content of 12-15%, and sieving to obtain qualified products;

[0041] (10) Curing and stabilization: Curing the product obtained in step (9) at 25-30° C. and 60-70% relative humidity for 7-10 days to obtain a finished product.

[0042] Preferably, the salt-alkali tolerant plant in step (1) is selected from Suaeda salsa, alfalfa or Poa annua L.

[0043] 8. The preparation method according to claim 6, characterized in that the fermentation medium in step (2) comprises: 10 g / L glucose, 5 g / L yeast extract, 3 g / L peptone, 2 g / L K2HPO4, 0.5 g / L MgSO4·7H2O, and the following substances are added according to the characteristics of the strain:

[0044] For the Sphingomonas prati strain, add L-tryptophan 0.5 g / L;

[0045] For Bacillus flexus strains, add choline 1 g / L;

[0046] For Staphylococcus sp. strains, add 30-50 g / L of NaCl.

[0047] Preferably, the fermentation parameters of the endophyte fermentation in step (2) are:

[0048] Sphingomonas prati: temperature 28 ± 1 ° C, pH 7.0 ± 0.2, dissolved oxygen 30-50%, fermentation time 36-48 hours;

[0049] Bacillus flexus: temperature 30 ± 1°C, pH 7.2 ± 0.2, dissolved oxygen ≥ 30%, fermentation time 24-30 hours;

[0050] Staphylococcus sp.: temperature 37±1℃, pH 7.0±0.2, dissolved oxygen ≥20%, fermentation time 18-24 hours.

[0051] Preferably, the parameters of the microwave-assisted infiltration treatment in step (6) are: microwave power 400-600W, intermittent treatment, and temperature controlled at ≤60°C.

[0052] The salt-alkali tolerant plant endophyte extract-biochar-based soil conditioner and its preparation method provided by the present invention have the following technical effects:

[0053] 1. Significant salt-alkali resistance effect: 3 months after the product is applied, the soil salt content can be reduced by more than 25%, the soil cation exchange capacity can be increased by more than 20%, and the aggregate stability can be increased by more than 30%.

[0054] 2. Crop growth is significantly promoted: rice yield increases by 15-25%, root activity increases by 30-50%, and plant salt resistance increases by more than 30%.

[0055] 3. The synergistic effect between biochar and endophytes is enhanced: the dual functions of salt adsorption and microbial activity are achieved. The stability of endophytic fermentation products on the biochar carrier is improved by more than 80%, and the survival rate of microorganisms under salt stress conditions is increased by more than 100%.

[0056] 4. Process innovation improves product quality: The use of vacuum negative pressure impregnation and microwave-assisted infiltration technology increases the functional component loading rate by more than 40% and the product stability by more than 50%.

[0057] 5. Improve both economic and environmental benefits: Use agricultural and forestry waste straw to prepare biochar, realizing resource recycling; after improving saline-alkali land, it can be cultivated sustainably for 3-5 years, with significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 The present invention is a flow chart of the preparation process of the salt-alkali tolerant plant endophyte extract-biochar based soil conditioner.

[0059] Figure 2 This is a growth curve of the salt-alkali tolerant plant endophyte used in the present invention under different salt concentrations.

[0060] Figure 3 This is a comparison chart of the effects of different activation conditions on the specific surface area and porosity of biochar in the present invention. DETAILED DESCRIPTION

[0061] The present invention will be further described in detail below in conjunction with specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the invention. The experimental methods for which specific conditions are not specified in the examples are generally carried out under conventional conditions or under conditions recommended by the manufacturer.

[0062] 1. Isolation and cultivation of salt-alkali tolerant plant endophytes

[0063] The salt-alkali tolerant plant endophytes used in the present invention are mainly isolated from salt-alkali tolerant plants such as Suaeda salsa, alfalfa (Medicagosativa), and Poa annua L. The isolation method is as follows:

[0064] (1) Collect healthy saline-alkali tolerant plant samples from coastal saline-alkali land with salinity > 0.5%;

[0065] (2) Disinfect the surface of the plant specimens by soaking in 75% alcohol for 30 seconds, soaking in 3% sodium hypochlorite solution for 5 minutes, and washing with sterile water three times;

[0066] (3) Cut the sterilized plant tissue into small pieces and grind them under sterile conditions;

[0067] (4) Preparation of 1×10 -1 to 1×10 -6 The gradient dilutions were spread on the separation medium containing 5% NaCl;

[0068] (5) Cultivate at 28°C for 48–72 hours, and select colonies with different morphological characteristics for purification;

[0069] (6) The bacterial species were identified by 16S rDNA sequencing, and endophytes with salt tolerance, such as Sphingomonas prati, Bacillus flexus, and Staphylococcus sp., were selected.

[0070] 2. Preparation and activation of straw biochar

[0071] The preparation method of the straw biochar used in the present invention is as follows:

[0072] (1) Raw material preparation: Collect rice or wheat straw, remove impurities, and air-dry to a moisture content of ≤15%;

[0073] (2) Mechanical crushing: Use a chopper and hammer mill to crush the straw into 5-10 mm;

[0074] (3) Pyrolysis carbonization: Place the crushed straw in a continuous rotary carbonization furnace, preheat at 100-200 °C for 1 hour under nitrogen protection, and then increase the temperature to 500-600 °C at a heating rate of 10 °C / min and maintain for 1-2 hours;

[0075] (4) Cooling and collection: Cool naturally to ≤50°C under nitrogen protection and collect the biochar;

[0076] (5) Biochar activation: There are two methods: alkaline activation and acid activation:

[0077] Alkali activation: Use 1-2 mol / L KOH solution, soak for 24 hours at a solid-liquid ratio of 1:5 (w / v), react at 60-80℃ for 4-6 hours, and wash until neutral;

[0078] Acid activation: Use 5-10% H3PO4 solution, soak for 24 hours at a solid-liquid ratio of 1:5 (w / v), react at 60-80℃ for 4-6 hours, and wash until neutral;

[0079] (6) Drying treatment: The activated biochar was dried at 105±5°C to a moisture content of ≤15%.

[0080] 3. Preparation of functional components

[0081] 1. Extraction of endophytic metabolites:

[0082] (1) Fermentation culture: The isolated endophytes are inoculated into the fermentation medium and fermentation culture is carried out under appropriate conditions;

[0083] (2) Centrifugation: centrifuge at 6000 rpm for 15 minutes and collect the supernatant;

[0084] (3) Membrane filtration: Use 0.45 μm membrane to remove residual bacteria;

[0085] (4) Concentration treatment: below 50°C and -0.08 MPa, concentrated to 1 / 5 of the original volume;

[0086] (5) Ethanol precipitation: Add ethanol to a final concentration of 60-70% and incubate at 4°C for 12 hours;

[0087] (6) Collect the precipitate: Centrifuge at 8000 rpm for 20 minutes and collect the precipitate;

[0088] (7) Freeze drying: After pre-freezing at -50°C, freeze-dry at -60°C and 13 Pa for 48 hours to obtain the endophyte metabolite extract.

[0089] 2. Preparation of amino acid chelates:

[0090] (1) Preparation of amino acid solution: Prepare an amino acid mixture (glycine, glutamic acid, lysine) into a 10% aqueous solution;

[0091] (2) Preparation of metal salt solution: prepare a 5% concentration mixed solution of MgSO4, CaCl2 and ZnSO4;

[0092] (3) Chelation reaction: Mix the amino acid solution and the metal salt solution in a ratio of 1:1, adjust the pH to 4.5-5.5, and react at room temperature for 2 hours;

[0093] (4) Concentration: Concentrate the reaction solution to a solid content ≥ 30%;

[0094] (5) Drying: Spray drying technology is used with an inlet temperature of 180-200°C and an outlet temperature of 80-90°C to obtain amino acid chelate powder.

[0095] 4. Composite functionalization and granulation process

[0096] 1. Preparation of functional composite liquid:

[0097] (1) mixing an endophyte metabolite extract, an amino acid chelate, and betaine in a certain proportion;

[0098] (2) Adjust the pH to 6.0-6.5 and react at 40-50°C for 2-3 hours;

[0099] (3) Cooling to room temperature to obtain a functional composite liquid.

[0100] 2. Biochar functionalization treatment:

[0101] (1) Biochar pretreatment: Dry the activated biochar at 80-100°C for 2-4 hours to reduce the moisture content to ≤5%;

[0102] (2) Vacuum negative pressure treatment: Place the pretreated biochar in a vacuum impregnation tank and evacuate to -0.08 to -0.09 MPa for 30 to 60 minutes;

[0103] (3) Immersion treatment: Under negative pressure, add functional composite liquid at a ratio of 1:3-1:5 (w / v) and immerse for 2-4 hours;

[0104] (4) Microwave-assisted infiltration: 400-600 W microwave power, intermittent treatment for 5-10 minutes, control temperature ≤ 60 °C;

[0105] (5) Drying: Dry at 50-60°C for 4-6 hours until the moisture content is ≤15% to obtain functionalized biochar.

[0106] 3. Component mixing and granulation:

[0107] (1) Functionalized biochar is mixed with bentonite, zeolite powder and auxiliary materials according to the formula ratio;

[0108] (2) Adjust the moisture content of the mixture to 18-22%;

[0109] (3) Add 3-5% sodium alginate solution as a binder;

[0110] (4) Use a rotary drum granulator to granulate, control the speed to 8-15 rpm, and the granulation time to 30-60 minutes;

[0111] (5) Control the particle size of the finished product to 2-4 mm.

[0112] 4. Drying and aging treatment:

[0113] (1) Place the granulated product in a multi-layer belt dryer and dry it according to the temperature curve:

[0114] Preheat at 40-50℃ for 30-60 minutes;

[0115] Main drying at 55-58℃ for 60-90 minutes;

[0116] Dry at a constant temperature of 50-55°C for 30-60 minutes;

[0117] (2) Drying to a moisture content of 12-15%;

[0118] (3) Screening: Use a 4 mm upper sieve and a 2 mm lower sieve to collect qualified products;

[0119] (4) Curing treatment: Curing the product at 25-30°C and relative humidity 60-70% for 7-10 days.

[0120] In the following examples, unless otherwise stated, all raw materials and reagents used were of commercially available analytical grade or homemade in the laboratory.

[0121] Example 1

[0122] (1) Cultivation of salt-alkali tolerant plant endophytes:

[0123] Sphingomonas prati was isolated from Suaeda salsa, cultured in R2A medium containing 3% NaCl at 28°C for 24 hours, and collected by centrifugation at 6000 rpm for 10 minutes.

[0124] (2) Endophytic fermentation and metabolite extraction:

[0125] The cells were inoculated into a fermentation medium (glucose 10 g / L, yeast extract 5 g / L, peptone 3 g / L, K2HPO4 2 g / L, MgSO4·7H2O 0.5 g / L, L-tryptophan 0.5 g / L) and fermented for 36 hours at 28°C, pH 7.0, and 30% dissolved oxygen. The supernatant was collected by centrifugation at 6000 rpm for 15 minutes, filtered through a 0.45 μm membrane, and concentrated at 50°C to 1 / 5 of its original volume. 95% ethanol was added to a final concentration of 60%, and the mixture was allowed to stand at 4°C for 12 hours. The precipitate was collected by centrifugation at 8000 rpm for 20 minutes, and freeze-dried for 48 hours to obtain an endophyte metabolite extract.

[0126] (3) Preparation of straw biochar:

[0127] Rice straw was crushed to 5 mm, pyrolyzed at 500 °C for 1 h under nitrogen protection, and naturally cooled to room temperature to obtain straw biochar.

[0128] (4) Biochar activation:

[0129] The biochar was soaked in 1 mol / L KOH solution at a solid-liquid ratio of 1:5 (w / v) for 24 h, washed to neutrality, and dried at 105 °C to obtain activated biochar with a specific surface area of ​​300 m 2 / g, porosity 60%, pH 7.5.

[0130] (5) Functional component compound:

[0131] 2 parts by weight of endophyte metabolite extract, 6 parts by weight of amino acid chelate (glycine:glutamic acid=1:1) and 2 parts by weight of betaine were mixed, the pH was adjusted to 6.5, and the mixture was reacted at 45°C for 2.5 hours to obtain a functional composite solution.

[0132] (6) Biochar functionalization:

[0133] The activated biochar was mixed with the functional composite liquid at a ratio of 1:3 (w / v) and impregnated for 3 hours under a vacuum condition of -0.08 MPa, intermittently treated with a microwave power of 400 W for 8 minutes, and dried at 55°C for 5 hours to obtain functionalized biochar.

[0134] (7) Component mixing and granulation:

[0135] Mix 50 parts by weight of functionalized biochar, 3 parts by weight of bentonite, 3 parts by weight of zeolite powder, 0.7 parts by weight of citric acid, 0.7 parts by weight of sodium alginate and 0.6 parts by weight of lignin sulfonate, adjust the moisture content to 20%, add 4% sodium alginate solution as a binder, and granulate using a rotary drum granulator at 10 rpm for 45 minutes to control the particle size to 2-4 mm.

[0136] (8) Drying and aging:

[0137] The granules were dried in a multi-layer belt dryer according to a temperature curve of preheating at 45°C for 45 minutes, main drying at 65°C for 75 minutes, and constant temperature drying at 50°C for 45 minutes to a moisture content of 13%. Qualified products were sieved and matured at 28°C and a relative humidity of 65% for 8 days to obtain the finished product.

[0138] The prepared soil conditioner is composed of: 10 parts by weight of salt-alkali tolerant plant endophyte fermentation product, 50 parts by weight of straw biochar, 6 parts by weight of amino acid chelate, 2 parts by weight of betaine compatible solute, 3 parts by weight of bentonite, 3 parts by weight of zeolite powder, and 2 parts by weight of auxiliary materials.

[0139] Example 2

[0140] Prepared according to the method of Example 1, except that:

[0141] (1) The salt- and alkali-tolerant plant endophyte, Bacillus flexus , was isolated from alfalfa ( Medicago sativa ) and cultured in TSB medium containing 4% NaCl at 30°C for 18 h.

[0142] (2) Add 1 g / L choline to the fermentation medium and ferment for 24 hours under the conditions of temperature 30°C, pH 7.2, and dissolved oxygen 40%;

[0143] (3) Straw biochar uses wheat straw as raw material and is pyrolyzed at 550 °C for 1.5 hours under nitrogen protection;

[0144] (4) Biochar activation was performed using 1.5 mol / L KOH solution;

[0145] (5) The amino acid chelate composition in the functional component complex is glycine:glutamic acid:lysine = 1:1:1;

[0146] (6) Biochar functionalization was performed using an intermittent microwave treatment at 500 W power for 7 minutes;

[0147] (7) The proportions of each component are as follows: 20 parts by weight of fermentation products of salt- and alkali-tolerant plant endophytes, 45 parts by weight of straw biochar, 10 parts by weight of amino acid chelate, 5 parts by weight of betaine-compatible solute, 2.5 parts by weight of bentonite, 2.5 parts by weight of zeolite powder, 1 part by weight of citric acid, 1 part by weight of sodium alginate, and 0.5 parts by weight of lignin sulfonate.

[0148] Example 3

[0149] Prepared according to the method of Example 1, except that:

[0150] (1) The salt-alkali tolerant plant endophyte Staphylococcus sp. was isolated from Poa annua L and cultured in NB medium containing 5% NaCl at 37°C for 18 h.

[0151] (2) The fermentation medium was supplemented with 40 g / L NaCl and fermented for 20 h at a temperature of 37°C, a pH of 7.0, and a dissolved oxygen content of 20%;

[0152] (3) The pyrolysis temperature of straw biochar was 600 °C and the pyrolysis time was 2 h;

[0153] (4) Biochar activation was performed using 10% H3PO4 solution;

[0154] (5) The amino acid chelate composition in the functional component complex is glutamic acid:lysine = 1:2;

[0155] (6) Biochar functionalization was performed by immersing the biochar at a vacuum of -0.09 MPa with the functional composite solution at a ratio of 1:5 (w / v) for 4 h and then intermittently treating the biochar with a microwave power of 600 W for 5 min;

[0156] (7) The proportions of each component are as follows: 30 parts by weight of fermentation products of salt- and alkali-tolerant plant endophytes, 40 parts by weight of straw biochar, 15 parts by weight of amino acid chelate, 10 parts by weight of betaine-compatible solute, 2 parts by weight of bentonite, 2 parts by weight of zeolite powder, 1 part by weight of citric acid, 1 part by weight of sodium alginate, and 1 part by weight of lignin sulfonate.

[0157] Example 4

[0158] Prepared according to the method of Example 1, except that:

[0159] (1) The salt- and alkali-tolerant plant endophyte is a 1:1 mixed strain of Sphingomonas prati and Bacillus flexus;

[0160] (2) The fermentation medium was a mixture of the appropriate culture media for each of the two strains, and the fermentation was carried out under the conditions of temperature 29°C, pH 7.1, and dissolved oxygen 35% for 30 hours;

[0161] (3) Straw biochar was prepared by mixing rice straw and wheat straw in a ratio of 1:1 and pyrolyzed at 525 °C for 1.2 h under nitrogen protection;

[0162] (4) Biochar activation was performed using 1 mol / L KOH solution and 5% H3PO4 solution sequentially for 24 h each;

[0163] (5) The amino acid chelate composition in the functional component complex is glycine:glutamic acid:lysine = 2:1:1;

[0164] (6) The proportions of each component are as follows: 15 parts by weight of fermentation product of salt- and alkali-tolerant plant endophytes, 60 parts by weight of straw biochar, 8 parts by weight of amino acid chelate, 3 parts by weight of betaine-compatible solute, 4 parts by weight of bentonite, 4 parts by weight of zeolite powder, 0.5 parts by weight of citric acid, 0.5 parts by weight of sodium alginate, and 0.5 parts by weight of lignin sulfonate.

[0165] Example 5

[0166] Prepared according to the method of Example 1, except that:

[0167] (1) The salt-alkali tolerant plant endophyte was a 1:1 mixed strain of Bacillus flexus and Staphylococcus sp.;

[0168] (2) Biochar activation was performed using 2 mol / L KOH solution;

[0169] (3) The functional component compounding temperature is 50°C and the reaction time is 3 hours;

[0170] (4) Biochar functionalization was performed using a vacuum of -0.085 MPa and an intermittent microwave power of 550 W for 6 min;

[0171] (5) Granulation was performed at a speed of 15 rpm and for 30 minutes;

[0172] (6) The proportions of each component are as follows: 25 parts by weight of fermentation products of salt- and alkali-tolerant plant endophytes, 55 parts by weight of straw biochar, 12 parts by weight of amino acid chelate, 7 parts by weight of betaine-compatible solute, 5 parts by weight of bentonite, 5 parts by weight of zeolite powder, 0.5 parts by weight of citric acid, 1 part by weight of sodium alginate, and 1 part by weight of lignin sulfonate.

[0173] Example 6

[0174] Prepared according to the method of Example 1, except that:

[0175] (1) The salt-alkali tolerant plant endophyte was a 1:1:1 mixed strain of Sphingomonas prati, Bacillus flexus, and Staphylococcus sp.;

[0176] (2) The pyrolysis temperature of straw biochar was 575 °C and the pyrolysis time was 1.5 h;

[0177] (3) Biochar functionalization was performed using microwave treatment at 500 W intermittently for 10 min;

[0178] (4) The drying temperature curve is: preheating at 40°C for 60 minutes, main drying at 70°C for 60 minutes, and constant temperature drying at 55°C for 30 minutes;

[0179] (5) Curing conditions are 25°C and 70% relative humidity for 10 days;

[0180] (6) The proportions of each component are as follows: 18 parts by weight of fermentation product of salt- and alkali-tolerant plant endophytes, 70 parts by weight of straw biochar, 5 parts by weight of amino acid chelate, 1 part by weight of betaine-compatible solute, 3 parts by weight of bentonite, 2 parts by weight of zeolite powder, 0.5 parts by weight of citric acid, 0.5 parts by weight of sodium alginate, and 0.5 parts by weight of lignin sulfonate.

[0181] Comparative Example 1

[0182] The method of Example 1 was used for preparation, except that the salt-tolerant plant endophyte was not used, but the non-salt-tolerant strain Bacillus subtilis isolated from ordinary soil was used.

[0183] Comparative Example 2

[0184] The preparation method was followed as in Example 1, except that the biochar was not activated or functionalized, and the biochar was directly mixed with other components to form granules.

[0185] Comparative Example 3

[0186] Ordinary organic fertilizers available on the market: organic matter content ≥45%, N+P2O5+K2O ≥5%, does not contain microbial components and biochar.

[0187] Effect test:

[0188] Test 1: Saline-alkali soil improvement effect test

[0189] The soil conditioners prepared in Examples 1-6 and Comparative Examples 1-3 were applied to paddy soil in a coastal salinized area with a salinity of 0.5% at a rate of 50 kg per mu. Soil samples were collected before application and 30, 60, and 90 days after application to measure soil salinity, pH, cation exchange capacity, organic matter content, and aggregate stability. The results are shown in Table 1 below:

[0190] Table 1 Effects of soil conditioners in various examples on the physical and chemical properties of saline-alkali soil

[0191]

[0192] As can be seen from Table 1, the soil conditioners prepared in Examples 1-6 of the present invention significantly improved saline-alkali soils compared to Comparative Examples 1-3. The soil salinity reduction rate in Examples 1-6 reached 25.6-30.2%, significantly higher than the 8.5-18.7% in Comparative Examples 1-3. The cation exchange capacity increased by 22.5-28.7%, significantly higher than the 6.3-15.8% in Comparative Examples 1-3. The aggregate stability increased by 32.6-38.5%, significantly higher than the 9.2-22.4% in Comparative Examples 1-3.

[0193] Among them, Example 3 had the best improvement effect, which may be related to its high proportion of salt-tolerant plant endophyte fermentation products (30 parts by weight) and amino acid chelates (15 parts by weight), which play an important role in improving saline-alkali soils. Comparative Example 1 used a non-salt-tolerant bacterial strain, which had reduced activity in high-salt environments and had a poor improvement effect. Comparative Example 2 did not undergo biochar activation and functionalization treatment, resulting in weak salt adsorption and microbial colonization capabilities. Comparative Example 3 did not contain microbial components or biochar, and had the worst improvement effect.

[0194] Test 2: Rice growth effect test

[0195] Rice was grown in the saline-alkali soil treated with Examples 1-6 and Comparative Examples 1-3, and the growth, yield, and quality of the rice were recorded. The results are shown in Table 2 below:

[0196] Table 2 Effects of soil conditioners in various examples on rice growth and yield

[0197]

[0198] As can be seen in Table 2, the growth and yield of rice in the soil treated with Examples 1-6 of the present invention were significantly better than those in Comparative Examples 1-3. The rice yield increase in Examples 1-6 reached 15.8-22.6%, significantly higher than the 4.2-10.5% in Comparative Examples 1-3; the biomass increase reached 22.6-30.1%, significantly higher than the 7.4-16.7% in Comparative Examples 1-3; and the root length increase reached 25.3-33.5%, significantly higher than the 8.3-18.2% in Comparative Examples 1-3.

[0199] Among them, Example 3 had the best promotion effect, with the rice yield increase rate reaching 22.6% and the biomass increase rate reaching 30.1%, which was consistent with the performance of Example 3 in the soil improvement effect test, further proving the effectiveness of the soil conditioner of the present invention.

[0200] Test 3: Salt-alkali tolerant microbial activity test

[0201] The soil conditioners prepared in Examples 1-6 and Comparative Examples 1-3 were added to soil containing different concentrations of NaCl (0%, 0.5%, 1.0%, 1.5%), and the number and activity of microorganisms in the soil were measured after culturing for 30 days.

[0202] The results are shown in Table 3 below:

[0203] Table 3 Microbial activity in soil conditioners of various examples under different salt concentrations (CFU / g)

[0204] Sample number 0% NaCl 0.5% NaCl 1.0% NaCl 1.5% NaCl Example 1 <![CDATA[8.5×10 8 ]]> <![CDATA[6.2×10 8 ]]> <![CDATA[3.8×10 8 ]]> <![CDATA[1.5×10 8 ]]> Example 2 <![CDATA[9.2×10 8 ]]> <![CDATA[7.3×10 8 ]]> <![CDATA[4.6×10 8 ]]> <![CDATA[2.0×10 8 ]]> Example 3 <![CDATA[1.0×10 9 ]]> <![CDATA[8.5×10 8 ]]> <![CDATA[5.7×110 8 ]]> <![CDATA[2.8×10 8 ]]> Example 4 <![CDATA[9.8×10 8 ]]> <![CDATA[7.9×10 8 ]]> <![CDATA[5.1×10 8 ]]> <![CDATA[2.3×10 8 ]]> Example 5 <![CDATA[9.5×10 8 ]]> <![CDATA[8.1×10 8 ]]> <![CDATA[5.4×10 8 ]]> <![CDATA[2.6×10 8 ]]> Example 6 <![CDATA[9.0×10 8 ]]> <![CDATA[6.8×10 8 ]]> <![CDATA[4.2×10 8 ]]> <![CDATA[1.8×10 8 ]]> Comparative Example 1 <![CDATA[8.0×10 8 ]]> <![CDATA[3.5×10 8 ]]> <![CDATA[1.2×10 8 ]]> <![CDATA[3.0×10 7 <!-- 10 -->]]> Comparative Example 2 <![CDATA[7.5×10 8 ]]> <![CDATA[4.1×10 8 ]]> <![CDATA[1.8×10 8 ]]> <![CDATA[5.2×10 7 ]]> Comparative Example 3 <![CDATA[5.2×10 8 ]]> <![CDATA[2.3×10 8 ]]> <![CDATA[6.5×10 7 ]]> <![CDATA[1.2×10 7 ]]>

[0205] As can be seen from Table 3, as the salt concentration increases, the microbial activity in each sample decreases, but the decrease in the microbial activity in Examples 1-6 of the present invention is significantly smaller than that in Comparative Examples 1-3. Under the condition of 1.5% NaCl, the microbial activity in Examples 1-6 remains at 1.5×10 8 -2.8×10 8 CFU / g, while the comparative examples 1-3 dropped to 1.2×10 7 -5.2×10 7 CFU / g, the difference is about one order of magnitude.

[0206] This shows that the salt-alkali tolerant plant endophyte extract-biochar-based soil improver of the present invention has significant salt tolerance and can maintain high microbial activity in a high-salt environment, which is an important mechanism for its efficient improvement of saline-alkali soil.

[0207] It can be seen from the above examples and effect tests that the salt-alkali tolerant plant endophyte extract-biochar-based soil conditioner and its preparation method provided by the present invention have the following advantages:

[0208] 1. Utilizing the special salt-tolerance mechanism of salt- and alkali-tolerant plant endophytes, the product’s stability and effectiveness in high-salt environments are improved;

[0209] 2. The synergistic effect of biochar and endophytic bacterial metabolites achieves the dual functions of salt adsorption and microbial activity;

[0210] 3. The use of vacuum negative pressure impregnation and microwave-assisted infiltration technology improves the functional component loading rate and product stability;

[0211] 4. The improvement effect of saline-alkali land such as rice fields in coastal salinization areas is significant, with the soil salt content reduced by more than 30% and rice yield increased by more than 22%.

[0212] The present invention makes full use of the special salt-tolerance mechanism of salt-alkali tolerant plant endophytes and the efficient adsorption characteristics of biochar to develop a highly efficient, environmentally friendly and economical saline-alkali soil conditioner with broad application prospects.

[0213] The foregoing is merely an embodiment of the present invention and is not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of the present invention.

Claims

1. Salt-alkali tolerant plant endophyte extract-biochar-based soil conditioner, characterized in that: Includes the following components: 10-30 parts by weight of a fermentation product of salt-alkali-tolerant plant endophytes; 40-70 parts by weight of straw biochar; 5-15 parts by weight of amino acid chelate; 1-10 parts by weight of a betaine-compatible solute; 2-5 parts by weight of bentonite; 2-5 parts by weight of zeolite powder; Auxiliary materials 1.5-3 parts by weight.

2. The soil conditioner according to claim 1, characterized in that The salt-alkali tolerant plant endophyte fermentation product is obtained by fermenting at least one endophyte selected from Sphingomonas prati, Bacillus flexus and Staphylococcus sp.

3. The soil conditioner according to claim 1, characterized in that The specific surface area of ​​the straw biochar is 200-600m 2 / g, porosity is 50-80%, and pH value is 7.0-9.

0.

4. The soil conditioner according to claim 1, characterized in that The amino acid chelate contains at least two of glycine, glutamic acid and lysine, and the total amino acid content is ≥40%.

5. The soil conditioner according to claim 1, characterized in that The auxiliary materials include 0.5-1 parts by weight of citric acid, 0.5-1 parts by weight of sodium alginate and 0.5-1 parts by weight of lignin sulfonate.

6. A method for preparing the salt-alkali tolerant plant endophyte extract-biochar-based soil conditioner according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Cultivation of salt-alkali tolerant plant endophytes: Salt-alkali tolerant endophytes were isolated and screened from salt-alkali tolerant plants, cultured in a medium containing 3-5% NaCl at 28-37°C for 18-48 hours, and the cells were collected by centrifugation; (2) Endophytic fermentation and metabolite extraction: The bacterial cells obtained in step (1) are inoculated into a fermentation medium, and fermented for 18-48 hours under the conditions of a temperature of 28-37°C, a pH of 6.5-7.5, and a dissolved oxygen content of 20-50%. The fermentation broth is collected by centrifugation and concentrated to 1 / 5 of the original volume, precipitated with ethanol, and the precipitate is collected and freeze-dried to obtain an endophytic metabolite extract; (3) Preparation of straw biochar: crush the straw to 5-10 mm, pyrolyze at 500-600 °C for 1-2 hours under nitrogen protection, and cool to room temperature to obtain straw biochar; (4) Biochar activation: The biochar obtained in step (3) was soaked in 1-2 mol / L KOH solution or 5-10% H3PO4 solution at a solid-liquid ratio of 1:5 (w / v) for 24 hours, washed to neutrality, and dried at 105±5°C to obtain activated biochar; (5) functional component compounding: mixing the endophyte metabolite extract obtained in step (2) with amino acids and betaine, reacting at 40-50° C. for 2-3 hours to obtain a functional compound solution; (6) Biochar functionalization: The activated biochar obtained in step (4) was mixed with the functional composite solution obtained in step (5) at a ratio of 1:3-1:5 (w / v) under a vacuum condition of -0.08 to -0.09 MPa and immersed for 2-4 hours, subjected to microwave-assisted infiltration treatment for 5-10 minutes, and dried at 50-60° C. to obtain functionalized biochar; (7) Component mixing: mixing the functionalized biochar obtained in step (6) with bentonite, zeolite powder and auxiliary materials, and stirring evenly; (8) Granulation: The mixture obtained in step (7) was adjusted to have a moisture content of 18-22%, 3-5% sodium alginate solution was added as a binder, and granulated using a rotary drum granulator to control the particle size to 2-4 mm; (9) Drying and sieving: The granules obtained in step (8) are dried in a multi-layer belt dryer according to a temperature profile of preheating at 40-50°C for 30-60 minutes, main drying at 55-58°C for 60-90 minutes, and constant temperature drying at 50-55°C for 30-60 minutes to a moisture content of 12-15%, and sieving to obtain qualified products; (10) Curing and stabilization: Curing the product obtained in step (9) at 25-30° C. and 60-70% relative humidity for 7-10 days to obtain a finished product.

7. The preparation method according to claim 6, characterized in that The salt-alkali tolerant plant in step (1) is selected from Suaeda salsa, Medicago sativa or Poa annua L.

8. The preparation method according to claim 6, characterized in that The fermentation medium in step (2) includes: 10 g / L glucose, 5 g / L yeast extract, 3 g / L peptone, 2 g / L K2HPO4, 0.5 g / L MgSO4·7H2O, and the following substances are added according to the characteristics of the strain: For Sphingomonas prati strain, add L-tryptophan 0.5 g / L; For Bacillus flexus strains, add choline 1 g / L; For Staphylococcus sp. strains, add 30-50 g / L of NaCl.

9. The preparation method according to claim 6, characterized in that The fermentation parameters of the endophyte fermentation in step (2) are: Sphingomonas prati: temperature 28 ± 1 ° C, pH 7.0 ± 0.2, dissolved oxygen 30-50%, fermentation time 36-48 hours; Bacillus flexus: temperature 30 ± 1°C, pH 7.2 ± 0.2, dissolved oxygen ≥ 30%, fermentation time 24-30 hours; Staphylococcus sp.: temperature 37±1℃, pH 7.0±0.2, dissolved oxygen ≥20%, fermentation time 18-24 hours.

10. The preparation method according to claim 6, characterized in that The parameters of the microwave-assisted infiltration treatment in step (6) are: microwave power 400-600W, intermittent treatment, and temperature controlled at ≤60°C.

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