A multifunctional soil conditioner for sandy soil along the Yellow River and its preparation method

Abstract

The present invention relates to a multifunctional soil conditioner for sandy soil along the Yellow River and a preparation method thereof, characterized in that the soil conditioner is a granular fertilizer, comprising a core layer and a coating layer wrapped outside the core layer, and the mass ratio of the core layer to the coating layer is 3-5:60-85; wherein the core layer raw materials are calculated by weight, including: 25-30 parts of phosphate rock powder, 15-25 parts of insoluble potassium ore powder, 5-10 parts of humic acid, and 15-20 parts of microbial agent; the coating layer is composed of modified sodium alginate. The modified sodium alginate outer coating prepared by the present invention has a uniform pore structure, can store water, provide a microenvironment required for the reproduction of beneficial microorganisms in the soil, increase the content of beneficial microorganisms in the soil, and gradually decompose slow-release phosphorus and potassium fertilizers.

Description

Technical Field

[0001] The invention relates to the field of fertilizers, and in particular to a multifunctional soil conditioner for sandy soil along the Yellow River and a preparation method thereof. Background Art

[0002] The Yellow River Basin is home to major agricultural product areas such as the Huang-Huai-Hai Plain, Fen-Wei Plain, and Hetao Irrigation Area. The cultivated land area and total grain output in the basin account for more than one-third of the country's total, making it an important grain production base in my country. In recent years, affected by climate change and human activities, land desertification along the Yellow River has become increasingly serious, with the total area of ​​sandy soil exceeding 58 million mu. Sandy soil has poor structure, weak water and fertilizer retention capacity, poor microbial activity, and poor nutrient effectiveness, making it difficult to achieve large-scale crop planting. Therefore, improving the fertility of sandy soil by carrying out soil remediation is of great significance to ensuring national food security.

[0003] Soil remediation can be mainly divided into physical, chemical, biological and agricultural measures, among which the application of soil conditioners is one of the effective measures to improve the soil environment. At present, the soil conditioners on the market are mainly divided into inorganic soil conditioners, organic soil conditioners and organic-inorganic soil conditioners. Their application fields are mainly for acidified land, saline-alkali land and heavy metal contaminated soil, while there are fewer soil conditioner products for sandy soil. For example, Chinese patent CN201410801226.1 discloses a mineral microbial soil conditioner suitable for sandy land. The soil conditioner is calculated by weight percentage: limestone 30-50%, humic acid 10-30%, zeolite 10-20%, silica 10-20%, winter mallow seeds 1-3%, turmeric 5-10% and Toosendan seeds 1-5%. The soil conditioner prepared by the invention mainly improves the structure of sandy soil, has a single function, and cannot fundamentally improve the planting environment of sandy soil. Therefore, there is an urgent need for a multifunctional soil conditioner product targeting sandy soil barrier factors. Summary of the invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a multifunctional soil conditioner for sandy soil along the Yellow River and a preparation method thereof.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] In a first aspect, the present invention provides a multifunctional soil conditioner for sandy soil along the Yellow River. The soil conditioner is a granular fertilizer, comprising a core layer and a coating layer wrapped outside the core layer, and the mass ratio of the core layer to the coating layer is 3-5:60-85; wherein the raw materials of the core layer are calculated by weight and include: 25-30 parts of phosphate rock powder, 15-25 parts of insoluble potassium rock powder, 5-10 parts of humic acid, and 15-20 parts of microbial agent; the component of the coating layer is modified sodium alginate.

[0007] Preferably, the particle size of the phosphate rock powder is 100-150 mesh.

[0008] Preferably, the insoluble potassium ore powder includes one or more of potassium feldspar powder and potassium mica powder.

[0009] Preferably, the particle size of the sparingly soluble potassium ore powder is 100-150 meshes.

[0010] Preferably, the microbial agent includes one or more of Bacillus subtilis, Bacillus gellinga and Bacillus coagulans.

[0011] Preferably, the preparation method of the modified sodium alginate comprises:

[0012] S1. Preparation of amino-modified sodium alginate:

[0013] Weigh sodium alginate and MES buffer, mix them, heat them to 55-75°C, stir them thoroughly until they are evenly dissolved, cool them to room temperature, add EDC·HCl, NHS and ethylenediamine, heat them to 40-60°C, keep them warm and stir them for 6-12 hours, cool them to room temperature, dialyze them in deionized water, and dry them to obtain amino-modified sodium alginate;

[0014] S2. Preparation of soybean oil modified sodium alginate:

[0015] Weigh epoxidized soybean oil and add it to tetrahydrofuran. After stirring thoroughly until uniform, add amino-modified sodium alginate, disperse it by ultrasonic until uniform, add a small amount of triethylamine dropwise, then heat to 50-60°C, reflux and stir for 3-6 hours, and remove the solvent by reduced pressure distillation to obtain soybean oil-modified sodium alginate.

[0016] Preferably, in S1, the pH of the MES (2-morpholineethanesulfonic acid) buffer is 4-6, and the mass ratio of sodium alginate to the MES buffer is 1:30-60.

[0017] Preferably, in S1, the mass ratio of EDC·HCl, NHS, ethylenediamine and sodium alginate is 2.4-3:0.9-1.3:3.2-5.6:1.

[0018] Preferably, in S1, EDC·HCl (carbodiimide hydrochloride) is first added, stirred at room temperature for 10-20 min, NHS (N-hydroxysuccinimide) is then added, stirred at room temperature for 30-60 min, and then ethylenediamine is added.

[0019] Preferably, in S1, during the dialysis process, the molecular weight cutoff of the dialysis bag is 3000-4000Da, the dialysis is performed for 2-3 days, and fresh deionized water is replaced every 6-8 hours.

[0020] Preferably, in S2, the mass ratio of amino-modified sodium alginate, epoxy soybean oil and tetrahydrofuran is 1:0.74-1.26:30-60.

[0021] Preferably, in S2, the frequency of ultrasonic dispersion is 20-40 kHz, and the ultrasonic time is 10-20 min.

[0022] Preferably, in S2, the amount of triethylamine added is 1.5%-5.5% of the mass of the amino-modified sodium alginate.

[0023] In a second aspect, the present invention provides a method for preparing a multifunctional soil conditioner for sandy soil along the Yellow River, comprising the following steps:

[0024] Step 1, weighing phosphate rock powder, insoluble potassium rock powder, humic acid, and microbial agent according to the number of parts, stirring them evenly and granulating them to obtain a granular core layer;

[0025] Step 2, mixing the modified sodium alginate with deionized water, and stirring thoroughly to form a modified sodium alginate coating solution;

[0026] Step 3, adding the granular core layer into a coating machine, then evenly spraying the modified sodium alginate coating solution under high temperature conditions, drying, cooling, and sieving to obtain a multifunctional soil conditioner for sandy soil along the Yellow River.

[0027] Preferably, the particle size of the granular core layer in step 1 is 2-2.5 mm.

[0028] Preferably, in step 2, the mass ratio of modified sodium alginate to deionized water is 1:1-2.

[0029] Preferably, the high temperature condition in step 3 is 75-80°C.

[0030] The beneficial effects of the present invention are:

[0031] 1. The soil conditioner prepared by the present invention is a slow-release fertilizer particle, including a core layer and a coating layer, wherein the coating layer is a slow-release protective layer, and the component is modified sodium alginate. The preparation process is that the sodium alginate is firstly amino-modified, and then the amino-modified sodium alginate is amino-epoxy bonded with epoxy soybean oil. The modified sodium alginate not only has good film-forming property and water absorption, but also has certain hydrophobicity and can be degraded, and has very good slow-release performance and the function of retaining water in sandy soil, and will not cause pollution to the environment.

[0032] 2. The modified sodium alginate outer membrane prepared by the present invention has a uniform pore structure, which can store water, provide a microenvironment required for the reproduction of beneficial microorganisms in the soil, increase the content of beneficial microorganisms in the soil, and gradually decompose slow-release phosphorus and potassium fertilizers.

[0033] 3. The fertilizer core prepared by the present invention includes phosphate rock powder and insoluble potassium rock powder, which can slowly release phosphorus, potassium and trace elements such as silicon under the action of microbial agents. The modified sodium alginate outer film can further control the nutrient release rate and avoid nutrient loss caused by poor fertilizer retention capacity of sandy soil.

[0034] 4. The fertilizer core prepared by the invention includes humic acid, which can improve the soil aggregate structure and enhance the activity of soil microorganisms. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is described below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to limit the scope of the present invention. The change or adjustment of the relative relationship thereof shall also be regarded as the scope of the present invention without substantially changing the technical content.

[0036] In order to better understand the above technical scheme, the exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0037] The present invention will be further described below in conjunction with the following examples.

[0038] Example 1

[0039] A multifunctional soil conditioner for sandy soil along the Yellow River, the soil conditioner is granular, and includes a core layer and an outer coating layer from the inside to the outside; in parts by weight, the coating layer is composed of 4 parts of modified sodium alginate, and the raw materials of the core layer include 28 parts of phosphate rock powder, 20 parts of insoluble potassium ore powder, 8 parts of humic acid, and 17 parts of microbial agent. The particle size of the phosphate rock powder is 130 mesh, the insoluble potassium ore powder is potassium feldspar powder, and the particle size is 130 mesh, and the microbial agent is composed of Bacillus subtilis and Bacillus gelatinus in a mass ratio of 1:1.

[0040] Wherein, the preparation method of the modified sodium alginate coating layer comprises:

[0041] S1. Preparation of amino-modified sodium alginate:

[0042] Weigh sodium alginate (molecular weight 8000) and MES (2-morpholineethanesulfonic acid) buffer with a pH of 5, mix them, the mass ratio of sodium alginate to MES buffer is 1:50, heat to 65°C, stir thoroughly until dissolved evenly, cool to room temperature, first add EDC·HCl (carbodiimide hydrochloride), stir at room temperature for 15 minutes, then add NHS (N-hydroxysuccinimide), stir at room temperature for 45 minutes, then add ethylenediamine, the mass ratio of EDC·HCl, NHS, ethylenediamine and sodium alginate is 2.7:1.1:4.4:1, heat to 50°C, keep stirring for 8 hours, cool to room temperature, dialyze in deionized water, the molecular weight cutoff of the dialysis bag is 3500Da, the dialysis is carried out for 2 days, and fresh deionized water is replaced every 7 hours, and after drying, amino-modified sodium alginate is obtained;

[0043] S2. Preparation of soybean oil modified sodium alginate:

[0044] Weigh epoxidized soybean oil (ESO) and add it to tetrahydrofuran. After stirring until uniform, add amino-modified sodium alginate and perform ultrasonic dispersion at a frequency of 30 kHz and a time of 15 min. Add triethylamine dropwise in an amount of 3.5% of the mass of the amino-modified sodium alginate. Then, heat to 55°C, reflux with stirring for 4 h, and remove the solvent by reduced pressure distillation to obtain soybean oil-modified sodium alginate.

[0045] The preparation steps of the multifunctional soil conditioner for sandy soil along the Yellow River are as follows:

[0046] (1) Weigh corresponding amounts of phosphate rock powder, insoluble potassium rock powder, humic acid, and microbial agent, stir them evenly, and then granulate them to obtain a granular core layer with a particle size of 2 mm;

[0047] (2) mixing the modified sodium alginate and deionized water in a mass ratio of 1:1.5, and stirring the mixture thoroughly to form a modified sodium alginate coating solution;

[0048] (3) The granular core layer prepared in (1) is added into a coating machine, and then the modified sodium alginate coating liquid is evenly sprayed at 75° C., dried, cooled, and sieved to obtain the multifunctional soil conditioner for sandy soil along the Yellow River.

[0049] Example 2

[0050] A multifunctional soil conditioner for sandy soil along the Yellow River, the soil conditioner is granular, and includes a core layer and an outer coating layer from the inside to the outside; in parts by weight, the coating layer is composed of 5 parts of modified sodium alginate, and the raw materials of the core layer include 30 parts of phosphate rock powder, 25 parts of insoluble potassium ore powder, 10 parts of humic acid, and 20 parts of microbial agent. The particle size of the phosphate rock powder is 150 mesh, the insoluble potassium ore powder is potassium feldspar powder and potassium mica powder, the mass ratio is 1:1, and the particle size is 150 mesh, and the microbial agent is composed of Bacillus subtilis, Bacillus gelatinus, and Bacillus coagulans in a mass ratio of 1:1:2.

[0051] The preparation method of the modified sodium alginate coating layer is the same as that in Example 1.

[0052] The preparation steps of the multifunctional soil conditioner for sandy soil along the Yellow River are as follows:

[0053] (1) Weigh corresponding amounts of phosphate rock powder, insoluble potassium rock powder, humic acid, and microbial agent, stir them evenly, and granulate them to obtain a granular core layer with a particle size of 2.5 mm;

[0054] (2) mixing the modified sodium alginate and deionized water in a mass ratio of 1:1, and stirring the mixture thoroughly to form a modified sodium alginate coating solution;

[0055] (3) The granular core layer prepared in (1) is added into a coating machine, and then the modified sodium alginate coating liquid is evenly sprayed at 80° C., dried, cooled, and sieved to obtain the multifunctional soil conditioner for sandy soil along the Yellow River.

[0056] Example 3

[0057] A multifunctional soil conditioner for sandy soil along the Yellow River, the soil conditioner is granular, and includes a core layer and an outer coating layer from the inside to the outside; in parts by weight, the coating layer is composed of 3 parts of modified sodium alginate, and the raw materials of the core layer include 30 parts of phosphate rock powder, 15 parts of insoluble potassium ore powder, 8 parts of humic acid, and 15 parts of microbial agent. The particle size of the phosphate rock powder is 100 mesh, the insoluble potassium ore powder is potassium mica powder, and the particle size is 100 mesh, and the microbial agent is composed of Bacillus subtilis, Bacillus gelatinus, and Bacillus coagulans in a mass ratio of 1:1:3.

[0058] The preparation method of the modified sodium alginate coating layer is the same as that in Example 1.

[0059] The preparation steps of the multifunctional soil conditioner for sandy soil along the Yellow River are as follows:

[0060] (1) Weigh corresponding amounts of phosphate rock powder, insoluble potassium rock powder, humic acid, and microbial agent, stir them evenly, and granulate them to obtain a granular core layer with a particle size of 2.5 mm;

[0061] (2) mixing the modified sodium alginate and deionized water in a mass ratio of 1:2, and stirring the mixture thoroughly to form a modified sodium alginate coating solution;

[0062] (3) The granular core layer prepared in (1) is added into a coating machine, and then the modified sodium alginate coating liquid is evenly sprayed at 80° C., dried, cooled, and sieved to obtain the multifunctional soil conditioner for sandy soil along the Yellow River.

[0063] Example 4

[0064] A multifunctional soil conditioner for sandy soil along the Yellow River, which differs from Example 1 only in that the preparation method of the modified sodium alginate coating layer is different.

[0065] The preparation method of the modified sodium alginate coating layer comprises:

[0066] S1. Preparation of amino-modified sodium alginate:

[0067] Weigh sodium alginate (molecular weight 6000) and MES (2-morpholineethanesulfonic acid) buffer with a pH of 4, mix them, the mass ratio of sodium alginate to MES buffer is 1:30, heat to 55°C, stir thoroughly until dissolved evenly, cool to room temperature, first add EDC·HCl (carbodiimide hydrochloride), stir at room temperature for 10-20 minutes, then add NHS (N-hydroxysuccinimide), stir at room temperature for 30 minutes, then add ethylenediamine, the mass ratio of EDC·HCl, NHS, ethylenediamine and sodium alginate is 2.4:0.9:3.2:1, heat to 40°C, keep stirring for 6 hours, cool to room temperature, dialyze in deionized water, the molecular weight cutoff of the dialysis bag is 3000Da, the dialysis is carried out for 2 days, and fresh deionized water is replaced every 6 hours, and after drying, amino-modified sodium alginate is obtained;

[0068] S2. Preparation of soybean oil modified sodium alginate:

[0069] Weigh epoxidized soybean oil (ESO) and add it to tetrahydrofuran. After stirring until uniform, add amino-modified sodium alginate and perform ultrasonic dispersion at an ultrasonic frequency of 20 kHz and an ultrasonic time of 10 min. Add triethylamine dropwise in an amount of 1.5% of the mass of the amino-modified sodium alginate. Then, heat to 50°C and reflux with stirring for 3 h. After removing the solvent by reduced pressure distillation, soybean oil-modified sodium alginate is obtained.

[0070] Example 5

[0071] A multifunctional soil conditioner for sandy soil along the Yellow River, which differs from Example 1 only in that the preparation method of the modified sodium alginate coating layer is different.

[0072] The preparation method of the modified sodium alginate coating layer comprises:

[0073] S1. Preparation of amino-modified sodium alginate:

[0074] Weigh sodium alginate (molecular weight 10000) and MES (2-morpholineethanesulfonic acid) buffer with a pH of 6, mix them, the mass ratio of sodium alginate to MES buffer is 1:60, heat to 75°C, stir thoroughly until dissolved evenly, cool to room temperature, first add EDC·HCl (carbodiimide hydrochloride), stir at room temperature for 20 minutes, then add NHS (N-hydroxysuccinimide), stir at room temperature for 60 minutes, then add ethylenediamine, the mass ratio of EDC·HCl, NHS, ethylenediamine and sodium alginate is 3:1.3:5.6:1, heat to 60°C, keep stirring for 12 hours, cool to room temperature, dialyze in deionized water, the molecular weight cutoff of the dialysis bag is 4000Da, the dialysis is carried out for 3 days, and fresh deionized water is replaced every 8 hours, and after drying, amino-modified sodium alginate is obtained;

[0075] S2. Preparation of soybean oil modified sodium alginate:

[0076] Weigh epoxidized soybean oil (ESO) and add it to tetrahydrofuran. After stirring until uniform, add amino-modified sodium alginate and perform ultrasonic dispersion at a frequency of 40 kHz for 20 min. Add triethylamine dropwise in an amount of 5.5% of the mass of the amino-modified sodium alginate. Then, heat to 60°C, reflux with stirring for 6 h, and remove the solvent by reduced pressure distillation to obtain soybean oil-modified sodium alginate.

[0077] Comparative Example 1

[0078] A soil conditioner, which is different from Example 2 only in that the modified sodium alginate coating layer is replaced by sodium alginate.

[0079] Comparative Example 2

[0080] A soil conditioner, which is different from Example 2 only in that no coating layer is added, and only a granular core layer is provided.

[0081] Comparative Example 3

[0082] No soil conditioners were applied.

[0083] Examples 1-3 and Comparative Examples 1-3 were combined with the base fertilizer nitrogen, phosphorus and potassium 16-16-16 compound fertilizer conventionally applied by local farmers to carry out the Kainong 176 peanut planting test, with the application amount of soil conditioner 300kg / mu and 16-16-16 compound fertilizer 50kg / mu. The test was carried out in a sandy soil in Kaifeng City, Henan Province from May 2023 to October 2023. The soil physical and chemical properties were: pH 6.14, organic matter 14.24g / kg, alkaline nitrogen 43.5mg / kg, available phosphorus 28.12mg / kg, and available potassium 145.85mg / kg.

[0084] The physical and chemical properties of the soil and the peanut yield indicators were measured respectively.

[0085] Table 1 Effects of different treatments on soil physical and chemical properties

[0086]

[0087] It can be seen that compared with the comparative example, the conditioner prepared in the embodiment of the present invention significantly improves the PAD index, porosity and soil water storage capacity of the surface aggregates of sandy soil.

[0088] Table 2 Effects of different treatments on peanut yield indicators

[0089] deal with Number of fruits per plant Number of unripe fruits per plant Dry yield per mu (kg / mu) Example 1 28.4 6.5 694.22 Example 2 30.2 6.1 705.81 Example 3 27.7 6.8 692.15 Comparative Example 1 24.5 7.0 657.21 Comparative Example 2 20.3 7.3 632.84 Comparative Example 3 16.7 8.2 552.17

[0090] It can be seen that compared with the comparative example, after applying the conditioning agent prepared in the embodiment of the present invention, the number of fruits per peanut plant is significantly increased, the number of empty fruits per plant is significantly decreased, and the dry yield per mu is significantly increased.

[0091] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily being directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0092] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A multifunctional soil conditioner for sandy soil along the Yellow River, characterized in that: The soil conditioner is a granular fertilizer, including a core layer and a coating layer wrapped outside the core layer, and the mass ratio of the core layer to the coating layer is 3-5:60-85; wherein the raw materials of the core layer are calculated by weight and include: 25-30 parts of phosphate rock powder, 15-25 parts of insoluble potassium rock powder, 5-10 parts of humic acid, and 15-20 parts of microbial agent; the coating layer is composed of modified sodium alginate; The microbial agent includes one or more of Bacillus subtilis, Bacillus gellingii, and Bacillus coagulans; The preparation method of the modified sodium alginate comprises: S1. Preparation of amino-modified sodium alginate: Weigh sodium alginate and MES buffer, mix them, heat them to 55-75°C, stir them thoroughly until they are evenly dissolved, cool them to room temperature, add EDC·HCl first, stir them at room temperature for 10-20 minutes, then add NHS, stir them at room temperature for 30-60 minutes, then add ethylenediamine, heat them to 40-60°C, keep them warm and stir them for 6-12 hours, cool them to room temperature, dialyze them in deionized water, and dry them to obtain amino-modified sodium alginate; S2. Preparation of soybean oil modified sodium alginate: Weigh epoxidized soybean oil and add it to tetrahydrofuran. After stirring thoroughly until uniform, add amino-modified sodium alginate, disperse it by ultrasonic until uniform, add a small amount of triethylamine dropwise, then heat to 50-60°C, reflux and stir for 3-6 hours, and remove the solvent by reduced pressure distillation to obtain soybean oil-modified sodium alginate.

2. A multifunctional soil conditioner for sandy soil along the Yellow River according to claim 1, characterized in that: The particle size of the phosphate rock powder is 100-150 mesh; the particle size of the insoluble potassium rock powder is 100-150 mesh.

3. A multifunctional soil conditioner for sandy soil along the Yellow River according to claim 1, characterized in that: The insoluble potassium ore powder includes one or more of potassium feldspar powder and potassium mica powder.

4. The multifunctional soil conditioner for sandy soil along the Yellow River according to claim 1, characterized in that: In the S1, the pH of the MES buffer is 4-6, and the mass ratio of sodium alginate to the MES buffer is 1:30-60.

5. The multifunctional soil conditioner for sandy soil along the Yellow River according to claim 1, characterized in that: In the S1, the mass ratio of EDC·HCl, NHS, ethylenediamine and sodium alginate is 2.4-3:0.9-1.3:3.2-5.6:

1.

6. The multifunctional soil conditioner for sandy soil along the Yellow River according to claim 1, characterized in that: In S1, during the dialysis process, the molecular weight cutoff of the dialysis bag is 3000-4000Da, the dialysis is performed for 2-3 days, and fresh deionized water is replaced every 6-8 hours.

7. The multifunctional soil conditioner for sandy soil along the Yellow River according to claim 1, characterized in that: In S2, the mass ratio of amino-modified sodium alginate, epoxidized soybean oil and tetrahydrofuran is 1:0.74-1.26:30-60; and the amount of triethylamine added is 1.5%-5.5% of the mass of amino-modified sodium alginate.

8. A method for preparing the multifunctional soil conditioner for sandy soil along the Yellow River according to claim 1, characterized in that: The following steps are involved: Step 1, weighing phosphate rock powder, insoluble potassium rock powder, humic acid, and microbial agent according to the number of parts, stirring them evenly and granulating them to obtain a granular core layer; Step 2, mixing the modified sodium alginate with deionized water, and stirring thoroughly to form a modified sodium alginate coating solution; Step 3, adding the granular core layer into a coating machine, then evenly spraying the modified sodium alginate coating solution under high temperature conditions, drying, cooling, and sieving to obtain a multifunctional soil conditioner for sandy soil along the Yellow River; The high temperature condition in step 3 is 75-80°C.

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