Soil remediation method for water retention and drought resistance

Abstract

The invention discloses a soil remediation method for water retention and drought resistance, and relates to the technical field of soil improvement, the method comprises the following steps: S1, material pretreatment; s2, preparing a composite water-retaining agent; s3, soil remediation; s4, performing saturated irrigation for the first time; according to the soil remediation method for water retention and drought resistance, the water retention and drought resistance of soil can be improved, ecological remediation of drought, salinization, desertification and degenerated soil is achieved, and therefore the problems that a traditional water-retaining agent is poor in salt resistance and insufficient in soil combination stability are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of soil improvement, in particular to a soil repair method for water conservation and drought resistance. Background Art

[0002] Drought, salinization, desertification, and soil degradation are detrimental to crop growth. Soil problems can impact agricultural production, the ecological environment, and sustainable land use. To improve soil's ability to retain water and resist drought, water-retaining agents (SUAs) are often added to the soil. However, in highly saline and alkaline soils, the high concentration of salt ions in the soil solution of traditional SUAs can disrupt their water-absorbing network, rendering them unable to effectively store water. Consequently, their water-retaining properties struggle to meet the water needs of plants in these saline and alkaline environments.

[0003] At the same time, traditional water-retaining agents lack stability in their bond with the soil. In the soil, water-retaining agents are easily displaced or lost due to factors such as water flow and the movement of soil particles, and cannot exert their water-retaining effect stably in the long term. Summary of the Invention

[0004] The purpose of the present invention is to provide a soil remediation method for water conservation and drought resistance. This soil remediation method for water conservation and drought resistance can improve the water conservation and drought resistance capacity of the soil, achieve ecological restoration of drought, salinization, desertification and degraded soil, thereby solving the problems of poor salt tolerance and insufficient stability of traditional water-retaining agents in combination with soil.

[0005] The above-mentioned optimized structure of the present invention is achieved through the following technical solutions: A soil remediation method for water conservation and drought resistance comprises the following steps: S1, material pretreatment: The acrylic acid-acrylamide copolymer resin is placed in a calcium chloride solution for pretreatment; Biochar with a particle size of less than 2 mm was premixed with humic acid and activated to form a porous carrier material. S2, preparation of composite water-retaining agent: The water-absorbing resin after salt-resistance treatment, porous carrier material, diatomaceous earth and Bacillus subtilis inoculum are prepared into a composite water-retaining agent according to weight percentage; S3, soil remediation: The prepared composite water-retaining agent is mixed with the soil by rotary tillage; S4, carry out the first saturation irrigation: A drip irrigation system is used for the first saturated irrigation, with the irrigation water volume being 120-150% of conventional irrigation, so that the composite water-retaining agent forms a slow-release water film; and an intelligent soil moisture monitoring system is established to dynamically adjust the irrigation threshold based on the monitoring data to maintain the soil moisture content at 60-70% of the field water holding capacity.

[0006] In some embodiments, in S1, the particle size of the acrylic acid-acrylamide copolymer resin is 0.1-0.5 mm, the calcium chloride solution is 0.5-1.5%, and the pretreatment time is 24 hours.

[0007] In some embodiments, in S1, the activation treatment of the biochar and humic acid is aging under certain temperature and humidity conditions.

[0008] In some embodiments, in S1, the biochar and the humic acid are premixed in a mass ratio of 3:1.

[0009] In some embodiments, in S2, the mass of the water-absorbing tree after salt tolerance treatment accounts for 40-60%, the mass of the porous carrier material accounts for 20-30%, the mass of the diatomaceous earth accounts for 10-20%, and the mass of the Bacillus subtilis agent accounts for 0.5-1%.

[0010] In some embodiments, in S2, the composite water-retaining agent is prepared by a twin-screw extrusion granulation process, and the composite water-retaining agent is a slow-release granule with a particle size of 1-3 mm.

[0011] In some embodiments, S3 includes the following steps: S31, digging out 5-20 cm thick surface soil, spreading a composite water-retaining agent on the surface of the deep soil, and rotary tilling and mixing the 20-40 cm thick deep soil and the composite water-retaining agent; S32, using a soil compactor to compact the deep soil after rotary tillage; S33, evenly spreading the surface soil and the composite water-retaining agent on the surface of the compacted deep soil, and rotary tilling and mixing the surface soil and the composite water-retaining agent.

[0012] In some embodiments, in said S31, the mass ratio of the composite water-retaining agent to the deep soil is 1%-3%, and in said S33, the mass ratio of the composite water-retaining agent to the surface soil is 3%-5%.

[0013] In some embodiments, before step S3, the soil needs to be subjected to a salt washing treatment, and the soil needs to be irrigated to a water depth of 20-30 cm. After standing for 24-48 hours, the water on the soil is drained.

[0014] In some embodiments, the method for preparing the acrylic acid-acrylamide copolymer resin comprises: Acrylic acid and acrylamide are mixed in a molar ratio of (2.5-3.5):1, 0.3%-0.8% of a crosslinking agent and 0.05%-0.15% of an initiator are added, and the mixture is reacted at 50-70° C. for 1.5-3 hours to prepare the acrylic acid-acrylamide copolymer resin.

[0015] One or more of the above technical solutions in the embodiments of the present invention have at least the following technical effects or advantages: (1) The present invention forms a composite water-retaining agent with a trinity functional system of water absorption, water fixation and slow release by mixing acrylic acid and acrylamide and combining the synergistic effect of biochar and humic acid, which can improve the water retention capacity of the soil and enhance the stability and sustainability of soil water retention. (2) The present invention combines porous carrier materials with diatomaceous earth to construct a multi-level pore structure of the composite water-retaining agent, thereby realizing the hierarchical storage of water. Different pore sizes can respectively play the functions of rapid water absorption, slow-release water supply and stable water storage, so that the composite water-retaining agent can better adapt to the water needs of plants under different environmental conditions and improve water utilization efficiency. (3) The present invention forms a dual water-retention structure in the soil by mixing different proportions of composite water-retention agents in the soil at different depths. This allows the soil to store more water when there is too much water, and to continuously supply water when there is insufficient water in the surface layer, thereby achieving dynamic regulation of water. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 Flowchart of the present invention. DETAILED DESCRIPTION

[0018] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0019] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0021] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0022] refer to Figure 1 , a soil remediation method for water conservation and drought resistance, comprising the following steps: S1, material pretreatment: First, an acrylic acid-acrylamide copolymer resin is prepared by mixing acrylic acid and acrylamide in a molar ratio of 2.5-3.5:1. 0.3%-0.8% of a crosslinker (such as N,N'-methylenebisacrylamide) and 0.05%-0.15% of an initiator (such as potassium persulfate) are added. The mixture is reacted at 50-70°C for 1.5-3 hours to produce the acrylic acid-acrylamide copolymer resin. After crosslinking, the acrylic acid-acrylamide copolymer resin forms a three-dimensional network structure with numerous hydrophilic groups. When mixed with soil and exposed to moisture, the resin absorbs large amounts of water through these hydrophilic groups, storing it within the network structure. This results in a high water absorption rate (≥500 g / g) and a water retention rate exceeding 80% in NaCl solution, demonstrating excellent salt tolerance.

[0023] Then, the acrylic acid-acrylamide copolymer resin is made into particles with a particle size of 0.1-0.5 mm to facilitate the full mixing of the acrylic acid-acrylamide copolymer resin with other substances. The acrylic acid-acrylamide copolymer resin is placed in a calcium chloride solution for pretreatment. The solubility of the calcium chloride solution can be 0.5-1.5%. The pretreatment time is 24 hours. The calcium ions (Ca² + ) can undergo cross-linking reaction with carboxyl groups and other groups in acrylic acid-acrylamide copolymer resin to form a more stable three-dimensional network structure.

[0024] Biochar with a particle size of less than 2 mm is premixed with humic acid and aged under certain temperature and humidity conditions to form a porous carrier material, thereby completing the pretreatment of the material. Biochar and humic acid can be premixed in a mass ratio of 3:1. Biochar has a rich pore structure that can increase the air permeability and water retention of the soil; humic acid contains a large number of active functional groups and has abundant negative charge sites, which can react with Na in saline-alkali soil. + Ion exchange reaction occurs to reduce the Na + The content of humic acid can reduce the salinization of the soil. At the same time, humic acid can promote the agglomeration of soil particles, improve the physical structure of the soil, increase the air permeability and water retention of the soil. After the two are mixed in a specific proportion and aged under certain temperature and humidity conditions, a porous carrier material with rich pores and high activity will be formed, providing a good foundation for the subsequent preparation of composite water-retaining agent.

[0025] S2, preparation of composite water-retaining agent: A composite water-retaining agent is formulated by weight based on a salt-resistant acrylic acid-acrylamide copolymer resin, a porous carrier material, diatomaceous earth, and a Bacillus subtilis inoculant. The salt-resistant acrylic acid-acrylamide copolymer resin accounts for 40-60% and is the core component of the composite water-retaining agent, providing the primary water absorption and retention capacity. The activated biochar-humic acid carrier accounts for 20-30%, synergizing with the absorbent resin to enhance water retention while also improving soil structure, regulating soil pH, and increasing soil fertility. Diatomaceous earth, with its large specific surface area and porous structure, accounts for 10-20%, further increasing the porosity of the composite water-retaining agent, enhancing its water absorption and retention capacity. It also helps improve soil permeability and can adsorb Cl in the soil. - Diatomaceous earth removes harmful ions such as ions and reduces the salt content of the soil. Furthermore, the porous structure of diatomaceous earth provides a habitat for soil microorganisms, promoting their growth and reproduction. Bacillus subtilis inoculants account for 0.5-1%. After colonizing the soil, Bacillus subtilis secretes a variety of bioactive substances, such as enzymes and antibiotics. These substances promote the decomposition of organic matter in the soil, converting large organic molecules into small nutrients, increasing the content of effective nutrients in the soil and providing sufficient nutrients for plant growth. At the same time, Bacillus subtilis can inhibit the growth of harmful microorganisms, regulate the structure of soil microbial communities, promote the reproduction of beneficial microorganisms, increase the soil microbial diversity index, form a benign material circulation system, and create a good soil ecological environment for plant growth.

[0026] The porous carrier material and the porous structure of diatomaceous earth further increase the water absorption and retention space of the composite water-retaining agent, forming a multi-level pore structure. Macropores (>50μm) absorb water rapidly, allowing the composite water-retaining agent to store large amounts of water in a short period of time. Mesopores (2-50μm) slowly release water during plant growth, achieving a slow-release water supply. Micropores (<2μm) stably store water, preventing rapid loss. This tiered water storage mechanism ensures that the soil provides a continuous water supply to plants regardless of time and environmental conditions.

[0027] S3, soil remediation: The prepared composite water-retaining agent is mixed with soil in a certain proportion by rotary tillage. Mixing the composite water-retaining agent with the soil can ensure that it has sufficient contact with the plant roots, effectively playing its role in water retention and soil improvement. At the same time, controlling the appropriate addition ratio can ensure the repair effect without causing negative impacts on the soil.

[0028] S4, carry out the first saturation irrigation: Use a drip irrigation system for the first saturated irrigation. The irrigation water volume is usually 120-150% of conventional irrigation, allowing the composite water retaining agent to form a slow-release water film. The composite water retaining agent fully absorbs water and expands, forming a stable water absorption and water retention structure in the soil, thereby forming a water slow-release channel, providing a continuous water supply for plant growth. The drip irrigation system can accurately control the irrigation water volume and irrigation uniformity, avoiding water waste and local water accumulation. Establish a soil moisture intelligent monitoring system to monitor soil moisture content in real time, and dynamically adjust the irrigation threshold based on the monitoring data to maintain the soil moisture content at 60-70% of the field water holding capacity. This water range can not only ensure that the plant roots have sufficient water supply, but also avoid problems such as reduced aeration and root hypoxia caused by excessive soil moisture, achieving precise irrigation and improving water use efficiency.

[0029] In some embodiments, in S2, the composite water-retaining agent can be produced using a twin-screw extrusion granulation process to produce slow-release granules with a particle size of 1-3 mm. This process allows the components to be thoroughly mixed and homogenized under high temperature, high pressure, and the shearing action of the screw, forming a stable composite material structure. Furthermore, the slow-release granules produced using this process exhibit good dispersibility and stability in soil, slowly releasing water and nutrients to meet the long-term growth needs of plants.

[0030] In some embodiments, S3 includes the following steps: S31: Excavate a 5-20 cm thick layer of topsoil and apply a composite water-retaining agent to the surface of the deeper soil layer. Rotary tillage and mix the 20-40 cm thick layer of deep soil with the composite water-retaining agent. Using excavation equipment such as an excavator, excavate a 5-20 cm thick layer of topsoil and temporarily set it aside. Then, evenly apply the composite water-retaining agent to the exposed deeper soil layer according to the pre-calculated dosage. Next, start the rotary tiller and adjust the tillage depth to just cover the deeper soil layer (20-40 cm thick). Repeated rotary tillage to thoroughly mix the composite water-retaining agent with the deeper soil layer and ensure its even distribution. This allows the composite water-retaining agent to penetrate deep into the root system, providing an excellent environment for deep root growth, improving soil quality, and promoting plant growth.

[0031] S32. After the deep soil and the composite water-retaining agent are thoroughly mixed, use a heavy-duty soil compactor to compact the deep soil after rotary tillage. The weight and speed of the soil compactor should be adjusted appropriately according to the soil texture. Generally, for clay soil, the weight of the soil compactor is slightly heavier and the speed is slightly slower; for sandy soil, the weight can be appropriately reduced and the speed can be increased. The purpose of compaction is to make the deep soil structure more compact, enhance the soil's ability to retain water and fertilizer, and provide a stable foundation for subsequent surface soil laying.

[0032] S33: Evenly mix the previously stored topsoil with an appropriate amount of the composite water-retaining agent. A small rotary tiller can be used to ensure the composite water-retaining agent is evenly distributed throughout the topsoil. Subsequently, the mixed topsoil is evenly spread over the compacted deeper soil, restoring the thickness to the original 5-20 cm. Finally, shallow tillage is performed again using the rotary tiller to further blend the topsoil and composite water-retaining agent. This allows the composite water-retaining agent to function within the topsoil, meeting the water and nutrient needs of the shallow plant roots while also improving the structure of the topsoil and enhancing its aeration and water retention.

[0033] In some embodiments, in S31, the mass ratio of the composite water retaining agent to the deep soil is 1%-3%. The deep soil mainly supports and provides deep nutrients and water for the plant roots. The lower ratio of the composite water retaining agent can maintain the soil porosity, avoid the decrease in air permeability caused by excessive expansion of the composite water retaining agent, and continuously release the adsorbed Ca² through the slow-release effect of diatomaceous earth. + Mg² +Plasma provides mineral nutrients for deep-rooted plants. In S33, the mass ratio of composite water-retaining agent to surface soil is 3%-5%. The surface soil is where plant roots directly contact and grow, and its demand for water and nutrients is more urgent. Appropriately increasing the proportion of composite water-retaining agent can better meet the growth needs of shallow plant roots. Simultaneously, the synergistic effect of humic acid and microorganisms promotes the growth and reproduction of surface soil microorganisms, improving the soil's ecological environment. By mixing composite water-retaining agents in different proportions in the surface soil and deep soil layers, a dual water-retention structure is formed in the soil. When water in the surface soil is insufficient, the deep soil water-retaining agent transports water to the surface layer through the matrix potential gradient, ensuring plant growth. When the surface soil moisture content is too high due to irrigation or rainfall, the excess water is absorbed and stored by the deep soil water-retaining agent, preventing nutrient leaching. This dual water-retaining structure of the surface and deep soil layers allows for more water to be stored.

[0034] In some embodiments, before step S3, the soil needs to be subjected to a salt washing treatment, and efficient irrigation equipment is selected to carry out large-scale irrigation on the soil so that the water depth on the soil reaches 20-30 cm. Maintain this water depth for 24-48 hours to allow the water to fully penetrate into the soil and dissolve the salt in the soil. During the standing process, the salt gradually diffuses into the entire soil solution as the water penetrates. After 24-48 hours, the drainage system, such as a pre-set drainage pipe or an excavated drainage ditch, is used to drain the salt-containing water out of the soil. The salt washing treatment can effectively reduce the salt content in the soil, create better soil conditions for the subsequent use of the composite water-retaining agent and plant growth, and avoid the adverse effects of high salt on the performance of the composite water-retaining agent and plant growth.

[0035] In order to make the technical objectives, technical solutions and technical effects of the present invention clearer and to facilitate those skilled in the art to understand and implement the present invention, the present invention will be further described in detail below with reference to specific embodiments.

[0036] Comparative Example 1: Using traditional water retaining agent without salt washing treatment Material preparation: Common starch-based water-retaining agents were selected and directly mixed with the soil at a mass ratio of 3% without any pretreatment or salt washing of the soil.

[0037] Soil remediation: Remediation was performed on saline-alkali land with a pH of 8.5 and an EC of 4.2 dS / m. Only the top 0-20 cm of soil was plowed, and the water-retaining agent was evenly applied and then rotary tilled. Deeper soil layers were not treated.

[0038] Irrigation method: Ordinary flood irrigation is adopted, and the irrigation water volume is the regular irrigation volume. The first saturated irrigation and subsequent intelligent monitoring and regulation are not carried out.

[0039] Comparative Example 2: Single use of untreated acrylic acid-acrylamide copolymer resin Material preparation: Acrylic acid-acrylamide copolymer resin was prepared without pretreatment with calcium chloride solution or addition of other ingredients and was directly mixed with soil at a mass ratio of 3%.

[0040] Soil remediation: Remediation was performed on a saline-alkali land with a pH of 8.3 and an EC of 4.4 dS / m. Similar to Comparative Example 1, only the topsoil was treated.

[0041] Irrigation method: Drip irrigation system is used. The initial irrigation water volume is 100% of the conventional irrigation volume, and there is no subsequent intelligent monitoring and regulation.

[0042] Comparative Example 3: Composite water-retaining agent lacking biochar-humic acid carrier Material preparation: When preparing the composite water-retaining agent, no biochar-humic acid carrier was added. The proportions of other ingredients were configured according to the minimum proportion in the invention content (40% salt-resistant acrylic acid-acrylamide copolymer resin, 10% diatomaceous earth, and 0.5% Bacillus subtilis agent), and mixed with the soil at a mass ratio of 3%.

[0043] Soil remediation: Soil remediation was carried out on a saline-alkali land with a pH of 8.5 and an EC of 4.2 dS / m. A layered mixing method was used, with 3% applied to the surface layer and 1% applied to the deep layer, but no salt washing was performed.

[0044] Irrigation method: The initial irrigation water volume is 100% of the soil saturated water holding capacity. A soil moisture monitoring system will be established subsequently, but the threshold will be set to a fixed value and will not be adjusted dynamically.

[0045] Example 1 Material Pretreatment: Strictly following the conditions described in the Summary of the Invention, acrylic acid and acrylamide were mixed in a 3:1 molar ratio. 0.5% crosslinker N,N'-methylenebisacrylamide and 0.1% initiator potassium persulfate were added. The mixture was reacted at 60°C for 2 hours to produce an acrylic acid-acrylamide copolymer resin. This resin was pelletized into 0.3 mm granules and pretreated with a 1% calcium chloride solution for 24 hours. Biochar with a particle size <2 mm was premixed with humic acid in a 3:1 mass ratio and aged at 30°C and 70% relative humidity for 7 days to form a porous carrier material.

[0046] Preparation of composite water-retaining agent: by mass percentage, salt-resistant treated acrylic acid-acrylamide copolymer resin accounts for 50%, activated biochar-humic acid carrier accounts for 25%, diatomaceous earth accounts for 15%, and Bacillus subtilis agent accounts for 1%. Slow-release particles with a particle size of 2 mm are prepared by a twin-screw extrusion granulation process.

[0047] Soil remediation: Remediation was carried out on a saline-alkali land with a pH of 8.6 and an EC value of 4.5 dS / m. First, the soil was desalted and watered to a depth of 25 cm using high-efficiency irrigation equipment. After standing for 36 hours, the soil was drained through drainage pipes. Next, a 10 cm thick layer of topsoil was excavated and a composite water-retaining agent was applied to the surface of the deeper soil at a rate of 1.5% by mass. The 20-40 cm thick layer of soil was then rotary tilled and mixed with the composite water-retaining agent. The deeper soil was compacted using a heavy-duty soil compactor. The temporarily stored topsoil was then mixed with the composite water-retaining agent at a rate of 4% by mass, spread on the surface of the compacted deeper soil, and shallowly tilled.

[0048] Irrigation management: A drip irrigation system was used for the first saturation irrigation, with a water volume of 130% of conventional irrigation, to form a slow-release water film. An intelligent soil moisture monitoring system was established to maintain soil moisture at 65% of field capacity.

[0049] Example 2 Material pretreatment and preparation of composite water-retaining agent: the same conditions as in Example 1.

[0050] Soil remediation: This was carried out on a separate saline-alkali land with a pH of 8.4 and an EC of 4 dS / m. The water depth for desalination was 20 cm, and the water was allowed to stand for 24 hours before draining. A 15 cm thick layer of topsoil was excavated, and a composite water-retaining agent was added to the deep soil at a 2% mass ratio, while the surface soil was mixed at a 3.5% mass ratio.

[0051] Irrigation management: The first irrigation volume is 120% of conventional irrigation, and the soil moisture monitoring system maintains the soil moisture at 60% of the field holding capacity.

[0052] For specific data comparison, please refer to Table 1 Table 1

[0053] From the data comparison, it can be seen that the embodiment is superior to the comparative example in all indicators, thereby verifying the effectiveness of the soil remediation method of the present invention.

[0054] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A soil remediation method for water conservation and drought resistance, characterized by: The following steps are involved: S1, material pretreatment: The acrylic acid-acrylamide copolymer resin is placed in a calcium chloride solution for pretreatment; Biochar with a particle size of less than 2 mm was premixed with humic acid and activated to form a porous carrier material. S2, preparation of composite water-retaining agent: The water-absorbing resin after salt-resistance treatment, porous carrier material, diatomaceous earth and Bacillus subtilis inoculum are prepared into a composite water-retaining agent according to weight percentage; S3, soil remediation: The prepared composite water-retaining agent is mixed with the soil by rotary tillage; S4, carry out the first saturation irrigation: A drip irrigation system is used for the first saturated irrigation, with the irrigation water volume being 120-150% of conventional irrigation, so that the composite water-retaining agent forms a slow-release water film; and an intelligent soil moisture monitoring system is established to dynamically adjust the irrigation threshold based on the monitoring data to maintain the soil moisture content at 60-70% of the field water holding capacity.

2. A soil remediation method for water conservation and drought resistance according to claim 1, characterized in that: In S1, the particle size of the acrylic acid-acrylamide copolymer resin is 0.1-0.5 mm, the calcium chloride solution is 0.5-1.5%, and the pretreatment time is 24 hours.

3. The soil remediation method for water conservation and drought resistance according to claim 1, characterized in that: In S1, the activation treatment of the biochar and humic acid is performed by aging under certain temperature and humidity conditions.

4. The soil remediation method for water conservation and drought resistance according to claim 1, characterized in that: In S1, the biochar and the humic acid are premixed in a mass ratio of 3:

1.

5. A soil remediation method for water conservation and drought resistance according to claim 1, characterized in that In S2, the mass of the water-absorbing tree after salt tolerance treatment accounts for 40-60%, the mass of the porous carrier material accounts for 20-30%, the mass of the diatomaceous earth accounts for 10-20%, and the mass of the Bacillus subtilis agent accounts for 0.5-1%.

6. The soil remediation method for water conservation and drought resistance according to claim 1, characterized in that: In S2, the composite water-retaining agent is prepared by a twin-screw extrusion granulation process, and the composite water-retaining agent is a slow-release granule with a particle size of 1-3 mm.

7. The soil remediation method for water conservation and drought resistance according to claim 1, characterized in that: The S3 includes the following steps: S31, digging out 5-20 cm thick surface soil, spreading a composite water-retaining agent on the surface of the deep soil, and rotary tilling and mixing the 20-40 cm thick deep soil and the composite water-retaining agent; S32, using a soil compactor to compact the deep soil after rotary tillage; S33, evenly spreading the surface soil and the composite water-retaining agent on the surface of the compacted deep soil, and rotary tilling and mixing the surface soil and the composite water-retaining agent.

8. The soil remediation method for water conservation and drought resistance according to claim 1, characterized in that: In the S31, the mass ratio of the composite water-retaining agent to the deep soil is 1%-3%, and in the S33, the mass ratio of the composite water-retaining agent to the surface soil is 3%-5%.

9. The soil remediation method for water conservation and drought resistance according to claim 1, characterized in that: Before step S3, the soil needs to be subjected to salt washing treatment, and irrigation is performed on the soil to a water depth of 20-30 cm. After standing for 24-48 hours, the water on the soil is drained.

10. The soil remediation method for water conservation and drought resistance according to claim 1, characterized in that: The preparation method of the acrylic acid-acrylamide copolymer resin comprises: Acrylic acid and acrylamide are mixed in a molar ratio of (2.5-3.5):1, 0.3%-0.8% of a crosslinking agent and 0.05%-0.15% of an initiator are added, and the mixture is reacted at 50-70° C. for 1.5-3 hours to prepare the acrylic acid-acrylamide copolymer resin.

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