A saline-alkali soil conditioner using waste and a preparation method thereof

Abstract

The application discloses a kind of saline-alkali soil modifier using waste, it relates to the technical field of soil improvement, including the following weight parts of raw materials: kitchen garbage 120-180 parts, urban river sludge 120-180 parts, phosphogypsum 120-180 parts, biochar particles 75-140 parts, humus 40-80 parts, microbial fermentation inoculum 10-20 parts, straw 20-30 parts, calcium superphosphate 15-30 parts, potassium fulvate 15-30 parts, urea 30-60 parts, carboxymethyl cellulose 25-40 parts, ammonium lauryl sulfate 25-40 parts, composting agent 10-20 parts and EDTA 20-40 parts.The kitchen garbage in the soil improvement agent has the effect of adhesion, can promote the formation of granular structure;And the formation of granular structure is conducive to the formation of urban river sludge component loose soil, reduce soil salinity, increase the porosity of soil;Phosphogypsum promotes the formation of soil granular structure, makes soil structure more stable, effectively reduces soil PH and soil salinity, various components are reasonable, interact, reduce soil salinity and PH, conducive to the normal growth of crops.

Description

Technical Field

[0001] This invention relates to the field of soil improvement technology, and more specifically to a soil conditioner for saline-alkali land using waste materials and its preparation method. Background Technology

[0002] Coastal saline-alkali land is a type of saline-alkali land. Due to long-term erosion and infiltration by seawater in coastal areas, neutral salts such as sodium chloride and sodium sulfate continuously accumulate in the soil, maintaining a pH of 7-8. The excessively high soil salinity inhibits plant growth and causes physiological drought, ultimately leading to wilting and even plant death. Coastal saline-alkali land poses a significant threat to crop growth. The Yellow River Delta region, which has long been affected by seawater infiltration, has a widespread distribution of saline-alkali soils with excessively high salinity, a salt composition consistent with seawater, high groundwater levels, and high mineralization. This makes it difficult for most crops to grow, severely impacting grain production and reducing land use efficiency. Therefore, reducing the salinity and lowering the soil pH in the coastal saline-alkali land of the Yellow River Delta is an urgent problem to be solved.

[0003] Kitchen waste, originating from food scraps in households, canteens, and school catering industries, is often only fermented for use as fertilizer or landfill. Improper handling can easily lead to spoilage, producing foul odors and impacting environmental quality. Rivers, as water carriers, are significantly affected by soil migration and deposition, causing blockages and hindering water transport. Urban river silt has high water content and poor engineering properties; its lack of utilization results in significant land occupation, and prolonged accumulation pollutes the environment, producing foul odors and affecting air quality. Phosphogypsum, a byproduct of wet phosphoric acid production, is a waste product. Each ton of phosphoric acid produced generates nearly five tons of phosphogypsum. While its main components are the same as natural gypsum, its effective utilization rate is less than 20%. Large quantities of phosphogypsum are still directly dumped, occupying land resources, imposing a heavy burden on production enterprises, and creating safety hazards and environmental pollution.

[0004] Therefore, how to solve the problem of waste reuse and improve the performance of saline-alkali land are problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a soil conditioner for saline-alkali land that utilizes waste materials, which solves the problem of recycling kitchen waste, urban river sludge and phosphogypsum, and significantly improves the properties of saline-alkali land soil.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A soil conditioner for saline-alkali land utilizing waste materials comprises the following raw materials in parts by weight: 120-180 parts kitchen waste, 120-180 parts urban river sludge, 120-180 parts phosphogypsum, 75-140 parts biochar granules, 40-80 parts humus, 10-20 parts microbial fermentation agent, 20-30 parts straw, 15-30 parts superphosphate, 15-30 parts potassium humate, 30-60 parts urea, 25-40 parts carboxymethyl cellulose, 25-40 parts ammonium dodecyl sulfate, 10-20 parts composting agent, and 20-40 parts EDTA.

[0008] This invention combines kitchen waste, urban river silt, and phosphogypsum, adding microbial agents and appropriate amounts of soil-required elements to create soil conditioner granules. The cellulose and starch components in the kitchen waste have a binding effect, promoting the formation of soil aggregates. The formation of these aggregates helps the urban river silt loosen the soil and reduce soil salinity. Simultaneously, the montmorillonite and other minerals in the urban river silt also contribute to soil loosening and increased porosity. Phosphogypsum further promotes the formation of soil aggregates, making the soil structure more stable, effectively reducing soil pH and salinity, and providing nutrients for crops. The interaction of these three components more effectively leverages the role of kitchen waste, urban river silt, phosphogypsum, and biochar granules in aggregate formation, resulting in a more rational soil structure, effectively preventing groundwater level rise, inhibiting salinization, and reducing soil salinity. The phosphate lime and urban river silt used also have a better effect on reducing soil pH.

[0009] Under the action of microbial agents, some organic matter in urban river silt and kitchen waste undergoes aerobic respiration, decomposing it into water and carbon dioxide, which can be absorbed and utilized by crops, thus promoting crop growth. Urban river silt and phosphogypsum contain nutrients such as nitrogen, phosphorus, and potassium, which are essential for crop growth. Under the nitrogen fixation and fermentation of microbial agents, these nutrients are provided to crops, which is beneficial for crop growth.

[0010] At the same time, when the soil amendment granules are released into the soil, the microbial agents will generate water, which is beneficial for the hydrolysis of carboxymethyl cellulose, allowing the amendment components to play a more rapid and complete role in the soil.

[0011] As a preferred technical solution, the saline-alkali soil conditioner comprises the following raw materials in parts by weight: 150 parts kitchen waste, 150 parts urban river sludge, 150 parts phosphogypsum, 90 parts biochar granules, 60 parts humus, 15 parts microbial fermentation agent, 25 parts straw, 20 parts superphosphate, 20 parts potassium humate, 50 parts urea, 35 parts carboxymethyl cellulose, 25 parts ammonium dodecyl sulfate, 15 parts composting agent, and 30 parts EDTA.

[0012] As a preferred technical solution, the microbial fermentation agent is a complex of Azotobacter chrysophyll and yeast, and the ratio of the number of live Azotobacter chrysophyll to yeast is 1:2, and the composting agent is Bacillus.

[0013] Another object of the present invention is to provide a method for preparing the above-mentioned saline-alkali soil conditioner, comprising the following steps:

[0014] (1) Mix biochar granules, humus and straw, add composting agent, add water to adjust the moisture content to 25%, carry out sealed fermentation, 20-25 days at 20℃, to obtain fermented material.

[0015] (2) Mix the fermentation material, urea, potassium humate and superphosphate evenly, then add EDTA and mix evenly to obtain the ready-to-use material;

[0016] (3) At 25℃, carboxymethyl cellulose was dissolved in 60% vol ethanol solution with a mass-volume ratio of ethanol to carboxymethyl cellulose of 1:1. Ammonium dodecyl sulfate was then added and stirred evenly. Kitchen waste, urban river sludge, phosphogypsum, biochar granules and microbial fermentation agent were then added and stirred evenly. The mixture was then mixed with the prepared materials and spray-dried. Granulation was carried out when the moisture content was 3%-7% to obtain a saline-alkali soil conditioner.

[0017] The ratio of biochar particles in step (1) to biochar particles in step (3) is 1:1.5.

[0018] As a preferred technical solution, the method for preparing the soil conditioner involves pre-treating the kitchen waste as follows: drying it at 90°C for 6 hours to reduce the moisture content to below 20%, and then pulverizing it to an average particle size of <0.5cm.

[0019] The urban river sludge was obtained through the following pretreatment: the urban river sludge was sun-dried for 7 days, then dried until the sludge moisture content was <2%, and then crushed to an average particle size of <5mm.

[0020] The phosphogypsum is obtained through the following pretreatment: industrial waste phosphogypsum is first neutralized with lime, then chemically treated, and then ground. After grinding, its fluorine content is ≤300mg / kg. If the content exceeds the standard, it is calcined at 400℃-600℃ until the requirements are met.

[0021] The biochar granules are obtained through the following pretreatment: straw and chicken manure are anaerobicly pyrolyzed at 560℃ for 30 min to obtain straw char and chicken manure char, respectively, and then mixed in a mass ratio of straw char and chicken manure char = 0.8:1.2, and ground through a 70-110 mesh sieve.

[0022] The humus is obtained through the following pretreatment: one or more of fallen leaves, corn stalks, and wheat stalks are fermented with EM bacteria.

[0023] Another object of the present invention is to provide a method for using the above-mentioned soil conditioner or the soil conditioner prepared by the above-mentioned preparation method, wherein the soil in the 0-40cm soil layer is dug out, the soil conditioner is spread in the 40cm deep layer, and the soil conditioner is mixed into the 40-80cm soil layer by machine tilling, and then the 0-40cm soil layer is backfilled.

[0024] As a preferred technical solution, the dosage of the soil conditioner is 50 kg / mu for slightly saline-alkali land, 100 kg / mu for moderately saline-alkali land, and 200 kg / mu for severely saline-alkali land.

[0025] Mildly saline-alkali land refers to land with a germination rate of 70-80% and a salt content of less than 0.3%. Severely saline-alkali land refers to land with a salt content of more than 0.6% and a germination rate of less than 50%. Land in between is moderately saline-alkali land.

[0026] This invention utilizes waste materials as a soil conditioner for saline-alkali land, which can effectively reduce the content of soluble salts and pH value in saline-alkali soil, significantly increase the content of nitrogen, phosphorus and potassium, effectively improve the physical and chemical properties of the soil, make the soil more fertile, prevent the surface soil from compacting, and promote normal crop growth. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention defines kitchen waste as waste generated in daily life, food processing, catering services, and workplace meals, including discarded vegetable leaves, leftover food, fruit peels, eggshells, tea dregs, bones, etc. Urban river sludge refers to silt separated from natural river channels in coastal cities. Phosphogypsum refers to phosphogypsum, a solid waste generated during the wet-process phosphoric acid production process, whose main component is calcium sulfate dihydrate.

[0029] Example 1

[0030] Raw material pretreatment

[0031] Kitchen waste is obtained through the following pretreatment: drying at 90℃ for 6 hours to reduce the moisture content to below 20%, and then crushing it to an average particle size of <0.5cm.

[0032] The urban river sludge was obtained through the following pretreatment: the urban river sludge was sun-dried for 7 days, then dried until the sludge moisture content was <2%, and then crushed to an average particle size of <5mm.

[0033] The phosphogypsum is obtained through the following pretreatment: industrial waste phosphogypsum is neutralized and modified by lime. After neutralization reaction by adding limestone, carbide slag or lime slurry, the pH value of the phosphogypsum is adjusted to 6.5 and then ground. After grinding, its fluorine content is ≤300mg / kg. If the content exceeds the standard, it is calcined at 400℃-600℃ until the requirements are met.

[0034] The biochar granules are obtained through the following pretreatment: straw and chicken manure are anaerobicly pyrolyzed at 560℃ for 30 min to obtain straw char and chicken manure char, respectively, and then mixed in a mass ratio of straw char and chicken manure char = 0.8:1.2, and ground through a 70-110 mesh sieve.

[0035] The humus is obtained through the following pretreatment: one or more of fallen leaves, corn stalks, and wheat stalks are fermented with EM bacteria.

[0036] The microbial fermentation inoculant was obtained through the following pretreatment: *Azotobacter chrysophagus* and yeast were fermented separately, and then combined at a live count ratio of 1:2. All microorganisms used were inoculum powders, with an effective live count of *Azotobacter chrysophagus* ≥ 1 × 10⁻⁶. 9 cfu / g, effective viable yeast count ≥5×10 8 cfu / g.

[0037] Straw is obtained through the following pretreatment: wheat straw or corn straw, one or both, dried and then crushed.

[0038] The composting agent is obtained through the following pretreatment: after fermentation with Bacillus, it is prepared into a bacterial powder, in which the number of effective viable bacteria is greater than or equal to 3 × 10⁻⁶. 10 cfu / g.

[0039] Example 2

[0040] A soil conditioner for saline-alkali land utilizing waste materials comprises the following raw materials in parts by weight: 120 parts kitchen waste, 120 parts urban river sludge, 180 parts phosphogypsum, 75 parts biochar granules, 40 parts humus, 10 parts microbial fermentation agent, 30 parts straw, 30 parts superphosphate, 30 parts potassium humate, 60 parts urea, 25 parts carboxymethyl cellulose, 25 parts ammonium dodecyl sulfate, 10 parts composting agent, and 20 parts EDTA.

[0041] Example 3

[0042] A soil conditioner for saline-alkali land utilizing waste materials comprises the following raw materials in parts by weight: 180 parts kitchen waste, 120 parts urban river sludge, 120 parts phosphogypsum, 140 parts biochar granules, 80 parts humus, 20 parts microbial fermentation agent, 20 parts straw, 15 parts superphosphate, 15 parts potassium humate, 30 parts urea, 40 parts carboxymethyl cellulose, 40 parts ammonium dodecyl sulfate, 20 parts composting agent, and 40 parts EDTA.

[0043] Example 4

[0044] A soil conditioner for saline-alkali land utilizing waste materials comprises the following raw materials in parts by weight: 150 parts kitchen waste, 150 parts urban river sludge, 150 parts phosphogypsum, 100 parts biochar granules, 60 parts humus, 15 parts microbial fermentation agent, 25 parts straw, 22 parts superphosphate, 22 parts potassium humate, 45 parts urea, 32 parts carboxymethyl cellulose, 32 parts ammonium dodecyl sulfate, 15 parts composting agent, and 30 parts EDTA.

[0045] Comparative Example 1

[0046] A soil conditioner for saline-alkali land utilizing waste materials comprises the following raw materials in parts by weight: 150 parts urban river sludge, 150 parts phosphogypsum, 100 parts biochar granules, 60 parts humus, 15 parts microbial fermentation agent, 25 parts straw, 22 parts superphosphate, 22 parts potassium humate, 45 parts urea, 32 parts carboxymethyl cellulose, 32 parts ammonium dodecyl sulfate, 15 parts composting agent, and 30 parts EDTA. It does not include kitchen waste.

[0047] Comparative Example 2

[0048] A soil conditioner for saline-alkali land utilizing waste materials comprises the following raw materials in parts by weight: 150 parts kitchen waste, 150 parts phosphogypsum, 100 parts biochar granules, 60 parts humus, 15 parts microbial fermentation agent, 25 parts straw, 22 parts superphosphate, 22 parts potassium humate, 45 parts urea, 32 parts carboxymethyl cellulose, 32 parts ammonium dodecyl sulfate, 15 parts composting agent, and 30 parts EDTA. It does not include urban river silt.

[0049] Comparative Example 3

[0050] A soil conditioner for saline-alkali land utilizing waste materials comprises the following raw materials in parts by weight: 150 parts kitchen waste, 150 parts urban river sludge, 100 parts biochar granules, 60 parts humus, 15 parts microbial fermentation agent, 25 parts straw, 22 parts superphosphate, 22 parts potassium humate, 45 parts urea, 32 parts carboxymethyl cellulose, 32 parts ammonium dodecyl sulfate, 15 parts composting agent, and 30 parts EDTA.

[0051] Excluding phosphogypsum

[0052] Comparative Example 4

[0053] A soil conditioner for saline-alkali land utilizing waste materials comprises the following raw materials in parts by weight: 150 parts kitchen waste, 150 parts urban river sludge, 150 parts phosphogypsum, 100 parts biochar granules, 60 parts humus, 25 parts straw, 22 parts superphosphate, 22 parts potassium humate, 45 parts urea, 32 parts carboxymethyl cellulose, 32 parts ammonium dodecyl sulfate, 15 parts composting agent, and 30 parts EDTA. It does not include microbial fermentation agents.

[0054] Example 5

[0055] Preparation method (this step is omitted if it involves components not included in the comparative example.)

[0056] The preparation methods of the soil conditioners in Examples 2-4 and Comparative Examples 1-4 include the following steps:

[0057] (1) Mix biochar granules, humus and straw, add composting agent, add water to adjust the moisture content to 25%, carry out sealed fermentation, 20-25 days at 20℃, to obtain fermented material.

[0058] (2) Mix the fermentation material, urea, potassium humate and superphosphate evenly, then add EDTA and mix evenly to obtain the ready-to-use material;

[0059] (3) At 25℃, carboxymethyl cellulose was dissolved in 60% vol ethanol solution with a mass-volume ratio of ethanol to carboxymethyl cellulose of 1:1. Ammonium dodecyl sulfate was then added and stirred evenly. Kitchen waste, urban river sludge, phosphogypsum, biochar granules and microbial fermentation agent were then added and stirred evenly. The mixture was then mixed with the prepared materials and spray-dried. Granulation was carried out when the moisture content was 3%-7% to obtain a saline-alkali soil conditioner.

[0060] The ratio of biochar particles in step (1) to biochar particles in step (3) is 1:1.5.

[0061] Example 6

[0062] How to use

[0063] Excavate the soil from the 0-40cm layer, spread the soil conditioner to the 40cm depth, and then mix the soil conditioner into the 40-80cm soil layer by machine tilling, before backfilling the 0-40cm soil layer.

[0064] Dosage: For slightly saline-alkali land, the dosage of the soil conditioner is 50 kg / mu; for moderately saline-alkali land, the dosage is 100 kg / mu; for severely saline-alkali land, the dosage is 200 kg / mu. (Slightly saline-alkali land refers to land with a germination rate of 70-80% and a salt content below 0.3%; severely saline-alkali land refers to land with a salt content exceeding 0.6% and a germination rate below 50%; moderately saline-alkali land falls between these two categories.)

[0065] Example 1

[0066] An 8-mu (approximately 0.87 hectares) experimental field of slightly saline-alkali land was evenly divided into eight plots, numbered 1-8. Plots 1-3 corresponded to the soil conditioners in Examples 2-4, respectively, while plots 4-7 corresponded to the soil conditioners in Examples 1-4. The dosage of soil conditioner in plots 1-7 was 50 kg / mu. Plot 8 served as a blank control, receiving no soil conditioner and undergoing normal fertilization as plots 1-7 during crop planting. All eight plots were treated simultaneously. Soil samples were taken before and after treatment. At 0, 5, 15, 25, and 30 days after treatment, soil samples were taken at depths of 20 cm, 40 cm, and 80 cm for analysis of salt concentration (EC value) and pH. At 30 days, the content of organic matter and available phosphorus in the soil at a depth of 60 cm was also measured.

[0067] Table 1 Soluble Salt Index

[0068]

[0069] As can be seen from the data in the table, the EC values ​​of the saline-alkali land treated by the methods in Examples 2-4 of this invention can all reach between 0.76 and 0.96 ms / cm on the thirtieth day, indicating that the method of this invention can effectively reduce the content of soluble salts in the soil.

[0070] After treatment, the EC value of Plot 4 gradually decreased, but remained above 1.06 ms / cm at 30 days, indicating that not using kitchen waste could reduce the content of soluble salts in the soil, but the effect was not as good as that of Plot 3. After treatment, the EC value of Plot 5 gradually decreased, but remained above 1.05 ms / cm at 30 days, indicating that not using urban river silt could reduce the content of soluble salts in the soil, but the effect was not as good as that of Plot 3. After treatment, the EC value of Plot 6 gradually decreased, but remained above 1.25 ms / cm at 30 days, indicating that not using phosphogypsum could reduce the content of soluble salts in the soil, but the rate of reduction was not as efficient as that of Plot 3 within 30 days. Compared with Plot 4, the lack of microbial agents in Plot 7 could reduce the EC value in the soil, but the effect was not as good as that of Plot 4. Compared with Plot 8, the treatments in Plots 1-7 could reduce the content of soluble salts in the soil.

[0071] Table 2 Soil pH Index

[0072]

[0073] The data in the table show that the pH of saline-alkali land treated by the methods in Examples 2-4 of this invention was below 7.34. The methods of this invention effectively reduce the alkali content in the soil, transforming severely saline-alkali land into slightly alkaline soil. After treatment, the pH of lands 4-7 gradually decreased, but the results were not as good as those of land 3. Treatments 1-7 showed a significantly greater effect on reducing soil pH compared to land 8.

[0074] Table 3 Nutritional content indicators

[0075]

[0076] The data in the table show that the saline-alkali lands No. 1-3 treated according to the methods in Examples 2-4 had higher contents of available nitrogen, available potassium, available phosphorus, and organic matter in the soil, with No. 3 showing the best results. Compared with No. 3, the contents of available nitrogen, available potassium, available phosphorus, and organic matter in the soils of comparative examples 4-8 were all lower, indicating that the method in Example 4 can effectively improve the physical and chemical properties of the soil, making the soil more fertile and the topsoil less prone to compaction.

[0077] Example 2

[0078] Three experimental plots, each one acre in size, were randomly selected from mildly, moderately, and severely saline-alkali lands. The mildly saline-alkali land was designated as plot 1, the moderately saline-alkali land as plot 2, and the severely saline-alkali land as plot 3. The soil conditioner prepared in Example 4 was applied at concentrations of 50 kg / acre, 100 kg / acre, and 200 kg / acre, respectively, and all three plots were treated simultaneously. Soil samples were taken before and after treatment. At 0, 5, 15, 25, and 30 days after treatment, soil samples were taken at depths of 20 cm, 40 cm, and 80 cm for analysis of salt concentration (EC value) and pH. At 30 days, the content of organic matter and available phosphorus in the soil at a depth of 60 cm was also measured.

[0079] Table 4 Soluble Salt Index

[0080]

[0081]

[0082] As can be seen from the data in the table, in the three saline-alkali lands (1-3) treated according to the method in Example 4, the EC value can reach between 0.75-0.95 ms / cm on the 30th day, indicating that the method of the present invention can effectively reduce the content of soluble salts in the soil when treating saline-alkali lands of different degrees.

[0083] Table 5 Soil pH Index

[0084]

[0085] The data in the table show that the pH values ​​of saline-alkali land plots 1-3, which were treated according to the method in Example 4 (light, medium, and heavy), were all below 7.18. This indicates that the method of the present invention can effectively reduce the pH of soil when treating saline-alkali land of different degrees.

[0086] Table 6 Nutritional content indicators

[0087]

[0088] The data in the table show that in the three saline-alkali lands (1-3) treated according to the method in Example 4, the contents of available nitrogen, available potassium, available phosphorus, and organic matter in the soil were relatively high. This indicates that using different dosages of the method in Example 4 to improve saline-alkali land can effectively improve the physical and chemical properties of the soil, making the soil more fertile and the topsoil more loose.

[0089] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0090] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A soil conditioner for saline-alkali land utilizing waste materials, characterized in that, It is composed of the following raw materials in parts by weight: 120-180 parts kitchen waste, 120-180 parts urban river sludge, 120-180 parts phosphogypsum, 75-140 parts biochar granules, 40-80 parts humus, 10-20 parts microbial fermentation agent, 20-30 parts straw, 15-30 parts superphosphate, 15-30 parts potassium humate, 30-60 parts urea, 25-40 parts carboxymethyl cellulose, 25-40 parts ammonium dodecyl sulfate, 10-20 parts composting agent, and 20-40 parts EDTA; The microbial fermentation agent is a complex of Azotobacter chrysophyll and yeast, and the ratio of viable Azotobacter chrysophyll to yeast is 1:

2. The composting agent is Bacillus. The method for preparing the soil conditioner includes the following steps: (1) Mix biochar granules, humus and straw, add composting agent, add water to adjust the moisture content to 25%, carry out sealed fermentation at 20℃ for 20-25 days to obtain fermented material; (2) Mix the fermentation material, urea, potassium humate and superphosphate evenly, then add EDTA and mix evenly to obtain the ready-to-use material; (3) At 25℃, carboxymethyl cellulose is dissolved in 60% vol ethanol solution, with the mass-volume ratio of ethanol to carboxymethyl cellulose being 1:

1. Then, ammonium dodecyl sulfate is added and stirred evenly. Then, kitchen waste, urban river sludge, phosphogypsum, biochar granules and microbial fermentation agent are added and stirred evenly. After mixing with the prepared materials, spray drying is carried out. When the moisture content is 3%-7%, granulation is carried out to obtain saline-alkali soil conditioner. The ratio of biochar particles in step (1) to biochar particles in step (3) is 1:1.

5.

2. The soil conditioner according to claim 1, characterized in that, It is composed of the following raw materials in parts by weight: 150 parts kitchen waste, 150 parts urban river sludge, 150 parts phosphogypsum, 100 parts biochar granules, 60 parts humus, 15 parts microbial fermentation agent, 25 parts straw, 22 parts superphosphate, 22 parts potassium humate, 45 parts urea, 32 parts carboxymethyl cellulose, 32 parts ammonium dodecyl sulfate, 15 parts composting agent, and 30 parts EDTA.

3. The method for preparing the soil conditioner according to claim 1 or 2, characterized in that, Includes the following steps: (1) Mix biochar granules, humus and straw, add composting agent, add water to adjust the moisture content to 25%, carry out sealed fermentation at 20℃ for 20-25 days to obtain fermented material; (2) Mix the fermentation material, urea, potassium humate and superphosphate evenly, then add EDTA and mix evenly to obtain the ready-to-use material; (3) At 25℃, carboxymethyl cellulose is dissolved in 60% vol ethanol solution, with the mass-volume ratio of ethanol to carboxymethyl cellulose being 1:

1. Then, ammonium dodecyl sulfate is added and stirred evenly. Then, kitchen waste, urban river sludge, phosphogypsum, biochar granules and microbial fermentation agent are added and stirred evenly. After mixing with the prepared materials, spray drying is carried out. When the moisture content is 3%-7%, granulation is carried out to obtain saline-alkali soil conditioner. The ratio of biochar particles in step (1) to biochar particles in step (3) is 1:1.

5.

4. The method for preparing the soil conditioner according to claim 3, characterized in that, The kitchen waste is obtained through the following pretreatment: drying at 90℃ for 6 hours to reduce the moisture content to less than 20%, and pulverizing to an average particle size of <0.5cm. The urban river sludge was obtained through the following pretreatment: the urban river sludge was sun-dried for 7 days, then dried until the sludge moisture content was <2%, and then crushed to an average particle size of <5mm. The phosphogypsum is obtained through the following pretreatment: industrial waste phosphogypsum is first neutralized with lime, then chemically treated, and then ground. After grinding, its fluorine content is ≤300mg / kg. If the content exceeds the standard, it is calcined at 400℃-600℃ until the requirements are met. The biochar particles are obtained through the following pretreatment: straw and chicken manure are anaerobicly pyrolyzed at 560℃ for 30 min to obtain straw char and chicken manure char, respectively, and then mixed in a mass ratio of straw char and chicken manure char = 0.8:1.2, and ground through a 70-110 mesh sieve. The humus is obtained through the following pretreatment: one or more of fallen leaves, corn stalks, and wheat stalks are fermented with EM bacteria.

5. The method of using the soil conditioner according to claim 1 or 2, or the soil conditioner prepared by the preparation method according to claim 3 or 4, characterized in that, Excavate the soil from the 0-40cm layer, spread the soil conditioner to the 40cm depth, and then mix the soil conditioner into the 40-80cm soil layer by machine tilling, before backfilling the 0-40cm soil layer.

6. The method of use according to claim 5, characterized in that, For slightly saline-alkali land, the dosage of the soil conditioner is 50 kg / mu; for moderately saline-alkali land, the dosage is 100 kg / mu; and for severely saline-alkali land, the dosage is 200 kg / mu.

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