Soil conditioner and method of making same

Abstract

The application discloses a soil conditioner and a preparation method thereof, relates to the technical field of soil improvement, and comprises the following steps: providing a first suspension and sodium hypochlorite, wherein the first suspension comprises bamboo fibers and alkali; mixing the first suspension and the sodium hypochlorite to obtain carboxylated nanometer bamboo fibers through reaction; providing a second suspension, a calcium salt and polyacrylamide, wherein the second suspension comprises the carboxylated nanometer bamboo fibers; and mixing the second suspension, the calcium salt and the polyacrylamide to obtain the soil conditioner. The soil conditioner prepared by the preparation method has excellent water retention, erosion resistance and the ability to improve the soil quality of saline-alkali land, and has a wide application prospect in the fields of repairing hardened soil, improving soil properties and promoting plant growth.

Description

Technical Field

[0001] This application relates to the field of soil amendment technology, and in particular to a soil amendment agent and its preparation method. Background Technology

[0002] Polymer-based soil conditioners (such as polyacrylamide and polyacrylic acid) promote the cementation of soil particles through strong binding properties, forming a stable aggregate structure and improving the physical properties of the soil. In recent years, they have been widely used in fields such as preventing soil erosion and remediating degraded soils.

[0003] However, commercially available polymer-based soil conditioners currently have limited functionality, and their effectiveness is greatly affected by soil type and environmental factors, which limits their use in severely damaged soils and complex, harsh environments. Summary of the Invention

[0004] In view of this, this application provides a soil conditioner and a method for preparing the same.

[0005] The embodiments of this application are implemented as follows: Firstly, the embodiments of this application provide a method for preparing a soil conditioner, comprising the following steps:

[0006] A first suspension and sodium hypochlorite are provided, wherein the first suspension includes bamboo fiber and alkali; the first suspension and the sodium hypochlorite are mixed and reacted to obtain carboxylated nano-bamboo fiber;

[0007] A second suspension, a calcium salt, and polyacrylamide are provided, wherein the second suspension includes the carboxylated bamboo nanofibers; the second suspension, the calcium salt, and the polyacrylamide are mixed to obtain a soil conditioner.

[0008] Optionally, in some embodiments of this application, the first suspension further includes a first solvent; the first solvent is selected from one or more of deionized water, tetrahydrofuran, ethyl acetate, and dimethyl sulfoxide.

[0009] The alkali is selected from one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide.

[0010] Optionally, in some embodiments of this application, the mass ratio of the bamboo fiber, the alkali, and the first solvent in the first suspension is (2~10):(10~50):(300~700).

[0011] The mass ratio of sodium hypochlorite to bamboo fiber is (1~5):(2~25).

[0012] Optionally, in some embodiments of this application, the reaction temperature between the first suspension and the sodium hypochlorite is 20°C to 80°C;

[0013] The reaction time between the first suspension and the sodium hypochlorite is 1-10 hours.

[0014] Optionally, in some embodiments of this application, the preparation method further includes: adding an acidic neutralizing agent to the reaction solution after the reaction;

[0015] The acid neutralizing agent is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and acetic acid.

[0016] Optionally, in some embodiments of this application, the second suspension further includes a second solvent; the second solvent is selected from one or more of distilled water, deionized water, ethanol, propylene glycol, and dimethyl sulfoxide.

[0017] The calcium salt is selected from one or more of calcium chloride, calcium nitrate, calcium acetate, and calcium formate.

[0018] Optionally, in some embodiments of this application, the mass concentration of the carboxylated bamboo nanofibers in the second suspension is 5 g / L to 50 g / L;

[0019] The mass ratio of the carboxylated bamboo nanofiber, the calcium salt, and the polyacrylamide is (2~10):(0.1~2):(2~10).

[0020] Optionally, in some embodiments of this application, the mixing of the second suspension, the calcium salt, and the polyacrylamide further includes: stirring;

[0021] The stirring time is 0.5h to 5h; the stirring temperature is 20℃ to 40℃.

[0022] Optionally, in some embodiments of this application, the mixing of the second suspension, the calcium salt, and the polyacrylamide further includes: removing the second solvent.

[0023] Secondly, embodiments of this application also provide a soil conditioner, which is prepared by the above method.

[0024] The soil conditioner preparation method provided in this application uses carboxylated bamboo nanofibers and polyacrylamide as the main components to construct the soil conditioner. The carboxyl groups abundant in the carboxylated bamboo nanofibers adsorb calcium ions, resulting in a high concentration of calcium ions in the conditioner. The hydroxyl and carboxyl groups on the surface of the carboxylated bamboo nanofibers, as well as the amide groups of the polyacrylamide, have strong affinity for water and provide water retention capacity. The carboxylated bamboo nanofibers act as a rigid framework, and are bonded to the polyacrylamide through hydrogen bonds. The polyacrylamide binds to soil particles through a cation bridge mechanism, forming large aggregates of carboxylated bamboo nanofibers, polyacrylamide, and soil, improving soil structure, increasing soil particle size, and enhancing soil erosion resistance. The carboxyl groups on the surface of the carboxylated bamboo nanofibers and the abundant calcium ions they carry bind with the alkaline ions of sodium carbonate and sodium bicarbonate in saline-alkali soils, significantly reducing soil pH. Simultaneously, the calcium ions replace sodium ions in soil colloids, reducing the toxic effects of sodium salts on plant water absorption. Furthermore, the carboxylated bamboo nanofibers, as an organic matter, can become soil nutrients after biodegradation.

[0025] The soil conditioner prepared by the method provided in this application has excellent water retention, erosion resistance and ability to improve saline-alkali soil quality, and has broad application prospects in the fields of repairing compacted soil, improving soil properties and promoting plant growth. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart of a method for preparing a soil conditioner provided in an embodiment of this application. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0029] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the orientation shown in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish a numerical order.

[0030] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0031] In this application, "at least one" means one or more, and "more than one" means two or more. "One or more", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0032] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0033] The structural formulas and molecular weights of some of the chemical reagents used in this application are described below:

[0034] Biodegradable bamboo fiber: short fiber, length 30~51mm, purchased from Shandong Xuzheng Textile Co., Ltd.

[0035] Urea: Molecular weight = 60.06;

[0036] Polyacrylamide: It is anionic, with a molecular weight of 18 million and a degree of hydrolysis of 5% to 17%.

[0037] The technical solution of this application is as follows:

[0038] Firstly, please refer to Figure 1 This application provides a method for preparing a soil conditioner, comprising the following steps:

[0039] Step S11: Provide a first suspension and sodium hypochlorite, wherein the first suspension includes bamboo fiber and alkali; mix the first suspension and the sodium hypochlorite and react to obtain carboxylated nano bamboo fiber;

[0040] Step S12: Provide a second suspension, calcium salt, and polyacrylamide, wherein the second suspension includes the carboxylated bamboo nanofibers; mix the second suspension, the calcium salt, and the polyacrylamide to obtain a soil conditioner.

[0041] It should be noted that the bamboo fiber is a short fiber with a length of 30mm to 51mm, which can be purchased from Shandong Xuzheng Textile Co., Ltd.

[0042] The soil conditioner preparation method provided in this application uses carboxylated bamboo nanofibers and polyacrylamide as the main components to construct the soil conditioner. The carboxyl groups abundant in the carboxylated bamboo nanofibers adsorb calcium ions, resulting in a high concentration of calcium ions in the conditioner. The hydroxyl and carboxyl groups on the surface of the carboxylated bamboo nanofibers, as well as the amide groups of the polyacrylamide, have strong affinity for water and provide water retention capacity. The carboxylated bamboo nanofibers act as a rigid framework, and are bonded to the polyacrylamide through hydrogen bonds. The polyacrylamide binds to soil particles through a cation bridge mechanism, forming large aggregates of carboxylated bamboo nanofibers, polyacrylamide, and soil, improving soil structure, increasing soil particle size, and enhancing soil erosion resistance. The carboxyl groups on the surface of the carboxylated bamboo nanofibers and the abundant calcium ions they carry bind with the alkaline ions of sodium carbonate and sodium bicarbonate in saline-alkali soils, significantly reducing soil pH. Simultaneously, the calcium ions replace sodium ions in soil colloids, reducing the toxic effects of sodium salts on plant water absorption. Furthermore, the carboxylated bamboo nanofibers, as an organic matter, can become soil nutrients after biodegradation.

[0043] The soil conditioner prepared by the method provided in this application has excellent water retention, erosion resistance and ability to improve saline-alkali soil quality, and has broad application prospects in the fields of repairing compacted soil, improving soil properties and promoting plant growth.

[0044] In step S11:

[0045] In some embodiments, the first suspension further includes a first solvent.

[0046] Furthermore, the first solvent is selected from one or more of deionized water, tetrahydrofuran, ethyl acetate, and dimethyl sulfoxide.

[0047] In some embodiments, the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide.

[0048] In some embodiments, the mass ratio of the bamboo fiber, the alkali, and the first solvent in the first suspension is (2~10):(10~50):(300~700), for example, it can be 2:15:360, 5:25:500, 7:35:540, 9:45:630, 10:50:700, or any range between two of the above ratios. Within the range of these mass ratios, it is beneficial for the bamboo fiber and the alkali to be fully dispersed in the first solvent.

[0049] In some embodiments, the first suspension is prepared using conventional techniques in the art; specifically, the bamboo fiber, the alkali, and the first solvent are mixed and stirred using an ultrasonic blender to obtain the first suspension.

[0050] In some embodiments, the mass ratio of sodium hypochlorite to bamboo fiber is (1~5):(2~25), for example, it can be 1:5, 2:9, 3:13, 4:18, 5:24, or any range between two of the above ratios. Within the range of the above mass ratio, it is beneficial for the reaction between sodium hypochlorite and bamboo fiber to proceed fully.

[0051] In some embodiments, the reaction temperature is 20℃~80℃, for example, it can be 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃ or any two of the above values; the reaction time is 1h-10h, for example, it can be 1h, 2h, 3h, 4h, 6h, 10h or any two of the above values; under the reaction conditions described above, it is beneficial for the sodium hypochlorite to oxidize the hydroxyl groups on the surface of the bamboo fiber to carboxyl groups under alkaline conditions, thereby obtaining the carboxylated nano-bamboo fiber.

[0052] In some embodiments, the carboxylated bamboo nanofibers are obtained by adding an acidic neutralizing agent to the reaction solution to adjust the pH of the reaction solution to neutral, followed by filtration and drying.

[0053] Furthermore, the acid neutralizing agent may be selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and acetic acid.

[0054] In step S12:

[0055] In some embodiments, the second suspension further includes a second solvent.

[0056] Furthermore, the second solvent is selected from one or more of distilled water, deionized water, tetrahydrofuran, ethyl acetate, and dimethyl sulfoxide.

[0057] In some embodiments, the mass concentration of the carboxylated bamboo nanofibers in the second suspension is 5 g / L to 50 g / L, for example, it can be 5 g / L, 10 g / L, 16 g / L, 25 g / L, 30 g / L, 45 g / L, 50 g / L or any two of the above values; within the mass concentration range described above, it is beneficial for the carboxylated bamboo nanofibers to be uniformly dispersed in the second solvent.

[0058] In some embodiments, the second suspension can be prepared by common techniques in the art; for example, after adding the carboxylated bamboo nanofibers to the second solvent, the dispersion of the carboxylated bamboo nanofibers can be promoted by heating, stirring, etc., to obtain the second suspension.

[0059] Furthermore, when heating, the heating temperature can be 40℃~60℃; stirring can be done by ultrasonic stirring, magnetic stirring or mechanical stirring, and the stirring time can be 1h~5h.

[0060] In some embodiments, the calcium salt is selected from one or more of calcium chloride, calcium nitrate, calcium acetate, and calcium formate.

[0061] In some embodiments, the mass ratio of the carboxylated bamboo nanofibers, the calcium salt, and the polyacrylamide is (2~10):(0.1~2):(2~10), for example, it can be 2:0.1:2, 5:0.2:5, 7:0.3:6, 9:1.1:7, 10:2:10, or any range between two of the above ratios. Within the mass ratio range described above, it is beneficial for the polyacrylamide to form a microgel with the carboxyl groups on the surface of the carboxylated bamboo nanofibers through strong hydrogen bonding, and it is also beneficial for the calcium ions provided by the calcium salt to be loaded onto the surface of the carboxylated bamboo nanofibers through electrostatic attraction with the carboxyl groups.

[0062] In some embodiments, after mixing the second suspension, the calcium salt, and the polyacrylamide, the mixture can be stirred for a duration of 0.5 h to 5 h, for example, 0.5 h, 1 h, 3 h, 4 h, or any two of the above values; the stirring temperature can be 20 °C to 40 °C.

[0063] In some embodiments, after stirring, the second solvent can be removed, dried, and pulverized in sequence to obtain a soil conditioner.

[0064] Furthermore, the drying can be carried out at room temperature or under vacuum; when vacuum drying is used, the drying temperature can be 60℃~100℃ and the drying time can be 2h~8h.

[0065] Furthermore, the removal of the second solvent can be achieved using common techniques in the art, such as filtration, adsorption, and centrifugation.

[0066] Secondly, this application also provides a soil conditioner, which is prepared by the above-described preparation method.

[0067] The soil conditioner provided in this application utilizes the carboxyl groups in carboxylated bamboo nanofibers to adsorb calcium ions, thereby enabling the conditioner to be loaded with a high concentration of calcium ions. Among them, the hydroxyl and carboxyl groups on the surface of carboxylated bamboo nanofibers, as well as the amide groups of polyacrylamide, have strong affinity for water and provide water retention capacity. As a rigid skeleton, carboxylated bamboo nanofibers are bonded to polyacrylamide through hydrogen bonds, and polyacrylamide is bonded to soil particles through a cation bridge mechanism. Carboxylated bamboo nanofibers, polyacrylamide, and soil form large particle aggregates, which improve soil structure, increase soil particle size, and enhance soil erosion resistance. The carboxyl groups on the surface of carboxylated bamboo nanofibers and the abundant calcium ions they carry combine with the alkaline ions of sodium carbonate and sodium bicarbonate in saline-alkali soil, significantly reducing the soil pH value. At the same time, calcium ions replace sodium ions in soil colloids, reducing the toxic effect of sodium salts on plant water absorption. In addition, as an organic matter, carboxylated bamboo nanofibers can become soil nutrients after biodegradation. With excellent water retention, erosion resistance, and ability to improve saline-alkali soil, it has broad application prospects in the fields of repairing compacted soil, improving soil properties, and promoting plant growth.

[0068] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0069] Example 1

[0070] This embodiment provides a soil conditioner, and the preparation method of the soil conditioner includes the following steps:

[0071] Step 1: Take 5g of biodegradable bamboo fiber (short fiber, length 30mm~51mm, purchased from Shandong Xuzheng Textile Co., Ltd.), 25g of sodium hydroxide, and 500g of deionized water and add them to an ultrasonic cell wall disruptor (power 800w). Treat at room temperature for 3h to obtain the first suspension. Transfer the first suspension to a 1000mL three-necked flask, add 1g of sodium hypochlorite, start stirring, and purge with flowing nitrogen for protection. React at 40℃ for 2h. Sodium hypochlorite oxidizes the hydroxyl groups on the surface of bamboo fiber to carboxyl groups under alkaline conditions. Then add hydrochloric acid to adjust the pH to neutral, filter, and dry to obtain carboxylated nano-bamboo fiber.

[0072] Step 2: Take 7g of carboxylated nano-bamboo fiber obtained in Step 1 and 300mL of distilled water, add them to a 1L beaker, and sonicate at 60℃ for 2h to obtain a second suspension. Add 0.2g of calcium chloride and 3g of polyacrylamide to the second suspension, and keep stirring vigorously for 1h. After stirring, filter to remove free water, put the obtained microgel into a vacuum oven, and vacuum dry at 80℃ for 4h. Then crush the obtained large particles with an agate mortar to obtain a soil conditioner.

[0073] Example 2

[0074] This embodiment is basically the same as Embodiment 1, except that the amount of carboxylated nano-bamboo fiber used in step 2 is 5g; the amount of polyacrylamide used is 5g.

[0075] Example 3

[0076] This embodiment is basically the same as Embodiment 1, except that the amount of carboxylated nano-bamboo fiber used in step 2 is 3g and the amount of polyacrylamide used is 7g.

[0077] Example 4

[0078] This embodiment is basically the same as Embodiment 1, except that in step 2, the amount of carboxylated nano-bamboo fiber used is 5g; the amount of polyacrylamide used is 5g; and the amount of calcium chloride used is 0.1g.

[0079] Example 5

[0080] This embodiment is basically the same as Embodiment 1, except that in step 2, the amount of carboxylated nano-bamboo fiber used is 5g; the amount of polyacrylamide used is 5g; and the amount of calcium chloride used is 0.3g.

[0081] Comparative Example 1

[0082] Commercially available soil conditioner (soil loosening agent, purchased from Shandong Fangchang Biotechnology Co., Ltd.)

[0083] Comparative Example 2

[0084] This comparison sample provides soil but does not include any soil conditioner.

[0085] The soil conditioners provided in Examples 1-5 and Comparative Example 1 were used to test water retention capacity, erosion resistance, improvement of soil calcium ion content, improvement of pH value of saline-alkali land, and ability to promote plant growth. The test results are shown in Table 1.

[0086] The soil used in the experiment was saline-alkali land in the Yinchuan Plain. Before the experiment, the soil was milled to obtain soil with uniform physical and chemical properties. The soil conditioner reported in each example and comparative example was weighed and milled with the soil at a mass ratio of 1:100 (comparative example 2 did not add soil conditioner). The mixture was shaken and mixed evenly in the sample bag for subsequent experiments.

[0087] Soil water retention performance test: Take 50g of improved soil and put it into a 500mL beaker. Add 15g of deionized water and leave it at room temperature for 5 days. Then weigh the soil in the beaker, m1. Soil water retention rate (wt) = (m1-50) / 15*100%.

[0088] Soil loss rate test: The soil loss rate (wt%) reflects the soil's ability to resist water erosion. Specifically, 50g of improved soil is weighed, dried at 80℃ and weighed as m2. The soil is placed in a 50cm long PVC pipe, and water is introduced at a flow rate of 0.8m / s for 30min to simulate water erosion. The remaining soil is then dried at 80℃ and weighed as m3. Soil loss rate (wt) = (m2 - m3) / m2 * 100%.

[0089] Soil average particle size test: The average particle size of the soil was measured using a laser particle size analyzer in accordance with standard GB / T19077.1-2008.

[0090] Calcium ion concentration test: The calcium ion concentration in the soil was determined by high-frequency plasma spectroscopy, in accordance with standard GB / T 50.123-2019.

[0091] pH test for improved saline-alkali land: Add 10g of soil to 100g of deionized water, stir for 0.5h, filter, and measure the pH value of the filtrate with a pH meter.

[0092] Plant growth promotion ability test: Peanut seeds were used to evaluate plant growth performance in this experiment. Before the test, the seeds were soaked in water for 24 hours to improve the germination rate. The peanut seedlings were planted for 30 days under constant temperature, light, watering and fertilization conditions, and the plant height of the peanut seedlings was tested.

[0093] Table 1

[0094] Soil water retention rate (wt%) 64.85 69.93 76.28 60.35 70.96 11.71 5.53 Soil loss rate (wt%) 33.26 29.14 27.55 33.19 19.82 61.83 73.72 Average soil particle size (μm) 664 735 779 634 893 477 386 Calcium ion concentration (mg / Kg) 447.52 444.59 451.18 226.93 583.76 27.34 26.79 pH value after soil improvement 7.1 7.1 7.2 7.8 6.7 10.6 10.8 Seed germination rate (%) 75.16 77.49 78.52 69.27 83.48 55.69 43.15 Plant height (cm) 23 23 24 20 26 16 14

[0095] The test data above show that the soil improved by the soil conditioner provided in this application has excellent water retention and resistance to water erosion compared to commercially available soil conditioners and soil without soil conditioner. This is mainly due to the skeletal effect of nano-bamboo fiber, the "bridging" of soil particles by polyacrylamide, and the combined effect of calcium ions replacing metal cations in soil particles, reducing the thickness of the double electron layer, which causes the soil to aggregate into larger particles. By loading a high concentration of soluble calcium ions, the concentration of calcium ions in the soil is significantly increased. The carboxyl groups on the surface of nano-bamboo fiber and the abundant calcium ions loaded combine with the alkaline ions of sodium carbonate and sodium bicarbonate in saline-alkali soil, significantly reducing the alkalinity of the soil. Calcium ions replace sodium ions in soil colloids, reducing the toxic effect of sodium salts on plant water absorption. In addition, as an organic matter, nano-bamboo fiber can become soil nutrients after biodegradation. The combined effect of these two factors significantly promotes plant growth.

[0096] The soil conditioner provided in this application has multiple functions such as excellent water retention, erosion resistance, and ability to improve saline-alkali soil quality. It has broad application prospects in the fields of repairing compacted soil, improving soil properties, and promoting plant growth.

[0097] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for preparing a soil conditioner, characterized in that, Includes the following steps: A first suspension and sodium hypochlorite are provided, wherein the first suspension includes bamboo fiber and alkali; the first suspension and the sodium hypochlorite are mixed and reacted to obtain carboxylated nano-bamboo fiber; A second suspension, a calcium salt, and polyacrylamide are provided, wherein the second suspension includes the carboxylated bamboo nanofibers; The second suspension, the calcium salt, and the polyacrylamide are mixed to obtain a soil conditioner. In the first suspension, the mass ratio of the bamboo fiber, the alkali, and the first solvent is (2~10):(10~50):(300~700). The mass ratio of sodium hypochlorite to bamboo fiber is (1~5):(2~25); The reaction temperature between the first suspension and the sodium hypochlorite is 20℃~80℃; The reaction time between the first suspension and the sodium hypochlorite is 1-10 hours. In the second suspension, the mass concentration of the carboxylated bamboo nanofibers is 5 g / L to 50 g / L; The mass ratio of the carboxylated bamboo nanofiber, the calcium salt, and the polyacrylamide is (2~10):(0.1~2):(2~10).

2. The preparation method according to claim 1, characterized in that, The first suspension further includes a first solvent; the first solvent is selected from one or more of deionized water, tetrahydrofuran, ethyl acetate, and dimethyl sulfoxide. The alkali is selected from one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide.

3. The preparation method according to claim 1, characterized in that, The preparation method further includes: adding an acidic neutralizing agent to the reaction solution after the reaction; The acid neutralizing agent is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and acetic acid.

4. The preparation method according to claim 1, characterized in that, The second suspension further includes a second solvent; the second solvent is selected from one or more of distilled water, deionized water, ethanol, propylene glycol, and dimethyl sulfoxide. The calcium salt is selected from one or more of calcium chloride, calcium nitrate, calcium acetate, and calcium formate.

5. The preparation method according to claim 1, characterized in that, The step of mixing the second suspension, the calcium salt, and the polyacrylamide further includes: stirring. The stirring time is 0.5h to 5h; the stirring temperature is 20℃ to 40℃.

6. The preparation method according to claim 1, characterized in that, The process of mixing the second suspension, the calcium salt, and the polyacrylamide further includes removing the second solvent.

7. A soil conditioner, characterized in that, The soil conditioner is prepared by any one of the preparation methods described in claims 1-6.

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