A system and method for constructing a physical isolation layer on saline-alkali soil and reconstructing a ploughing layer in situ

Abstract

This invention belongs to the field of saline-alkali land improvement technology, and discloses a system and method for constructing a physical isolation layer and in-situ regenerating a arable layer in saline-alkali land. The system integrates eight units and pioneers a "non-excavation in-situ membrane laying + simultaneous pipe laying" process to achieve a fully integrated process of "physical isolation + permeable drainage + soil improvement + field division + water and fertilizer maintenance". A closed-loop isolation system is constructed using isolation field ridges containing 15-20% quicklime and 0.6-1.5mm (lifespan over 50 years) HDPE membranes. This is combined with permeable blind pipes and a field ridge drainage system, along with drip / micro-irrigation technology and fish protein compound enzyme fertilizer with a molecular weight ≤500Da, forming a closed loop of "treatment-maintenance-yield increase". It overcomes the pain points of traditional technologies, shortens the treatment cycle by more than 80%, increases crop yield by 30-50%, saves more than 60% of water, and improves soil microbial activity by more than 25%. After improvement, the soil salinity is ≤0.1% and the pH value is 6.5-7.5. It has high desalination efficiency and stable effect, and is suitable for the improvement and cultivation of various types of saline-alkali land and heavy metal contaminated land.

Description

Technical Field

[0001] This invention relates to the fields of environmental protection and agricultural engineering technology, and in particular to a system and method for constructing a physical isolation layer and regenerating the arable layer in saline-alkali land. Specifically, it is a system and method that uses a physical isolation layer to block the migration of water and salt between soil layers, comprehensively and centrally treats and regenerates the original salt content in the planting layer above the plow layer, and scientifically regulates the nutrient activity of the planting layer soil. This system and method also integrates drip irrigation / micro-irrigation technology with the application of fish protein compound enzyme fertilizer to achieve deep soil improvement and efficient nutrient supplementation for crops. It is applicable to the improvement, treatment, and cultivation of various types of saline-alkali land. Background Technology

[0002] Saline-alkali land is one of the world's important land resources, but its high salinity and high pH value lead to soil structure deterioration and nutrient depletion, severely restricting agricultural production and ecological restoration. Existing saline-alkali land improvement technologies mainly include water-based desalination, chemical improvement, and biological improvement, but they generally suffer from the following drawbacks:

[0003] Water-based salt removal consumes a large amount of water, easily leading to water waste, and cannot prevent the upward migration of deep soil salts, making it difficult to maintain the improvement effect in the long term.

[0004] Chemical amendments are limited and can only adjust soil pH in the short term. They cannot improve soil structure and nutrient status, and long-term use can easily cause secondary pollution.

[0005] Biological improvement has a long cycle and slow results, and it is poorly adapted to severely saline-alkali land;

[0006] Existing technologies lack an integrated design of "isolation-desalination-improvement-nutrients", resulting in poor soil stability after improvement and limited increase in crop yield.

[0007] In recent years, many regions have attempted to improve saline-alkali land through physical barrier technology, but many key problems remain unresolved in practice. Typical cases are as follows:

[0008] Wuyuan County "Straw" Technology Case Background: Nearly 1 million mu of secondary saline-alkali land in the county, accounting for over 50% of the total arable land, suffers from elevated groundwater levels and upward migration of salt due to excessive irrigation. Treatment Method: Manual excavation is used to lay a 5-15cm layer of chopped straw at a depth of 30-40cm to form a physical barrier. Purpose and Limitations: While aiming to reduce capillary water salt migration and adsorb salt crystals, the treatment lacks long-term sustainability. Furthermore, manual excavation, laying, and backfilling are labor-intensive and inefficient, making large-scale promotion unsuitable.

[0009] Case Study: Biomass Intermediate Layer in Moderately Saline-Alkali Land, Ordos. Background: Moderately saline-alkali land along the Yellow River irrigation area, with a salt content of 0.4%-0.6%, pH > 8.5, low fertility, and severe surface salt accumulation. Treatment Method: Laying a 35-40cm deep layer of straw biomass as an intermediary, using 600-800kg per acre, combined with subsurface fertilization and fertigation. Purpose and Limitations: While intended to improve soil structure and inhibit salt migration, suitable for sunflower cultivation, practical experience shows it cannot completely block water and salt migration. Straw easily absorbs salt, forming heavy salt clumps, leading to a rebound in treatment effectiveness.

[0010] Case Study of "Terraced Fields + Biomass Barrier" in Leling: The terrain is low-lying with a groundwater level of only half a meter, making it prone to salt accumulation, resulting in over 100,000 mu (approximately 6,667 hectares) of abandoned saline-alkali land. Treatment Method: Raising the farmland to form terraced fields, with a biomass barrier layer deep within the terraces, and converting low-lying areas into drainage ditches, effectively blocking some water and salt migration; drainage ditches are also constructed on both sides of the terraces. Due to sunlight and temperature influences, high-concentration salt in these ditches easily migrates to the planting layer via capillary action in the surface soil. Objectives and Limitations: The core objective is to lower the groundwater level and reduce surface salt accumulation, but there is a risk of lateral salt backflow, and it cannot completely cut off the path of salt infiltration into the planting layer.

[0011] Alar Deep Tillage and Soil Loosening Case Background: The soil salinity is 16‰-30‰, with severe compaction, classifying it as severely saline-alkali land. Treatment Method: Deep tillage to a depth of 60cm to break up the compacted soil layer, mixing in 20% new soil from the top, middle, and bottom layers to form a loose, deep structure, coupled with an irrigation and drainage system to remove salt. Objectives and Limitations: While mixing new soil with crushed straw reduces soil salinity, it does not create a long-term salt barrier. Lower-layer salts can easily rise again with moisture, and the new soil preparation process is extensive and costly.

[0012] In summary, existing physical barrier technologies generally suffer from problems such as incomplete barrier function, easy rebound of effects, low operational efficiency, high cost, and limited applicability. There is an urgent need to develop an integrated technical solution that can fundamentally block salt migration, achieve efficient in-situ soil improvement, and enable long-term stable cultivation. Summary of the Invention

[0013] I. Purpose of the Invention

[0014] The purpose of this invention is to overcome the defects of the existing technology and provide a system for constructing a physical isolation layer and recreating a arable layer in saline-alkali land. Through an integrated design of physical isolation, in-situ desalination, compound improvement and precision nutrition, it can achieve deep improvement and efficient utilization of saline-alkali land.

[0015] II. Technical Solution

[0016] (I) System Structure

[0017] The system of the present invention includes a soil pretreatment unit, an isolation layer laying unit, a soil desalination unit, a soil conditioner addition unit (401), a soil backfilling and leveling unit (501), an irrigation and fertilization unit, a monitoring unit, and a permeable blind pipe laying system (916). Each unit works together to complete the improvement and treatment of saline-alkali land. The specific structure is as follows:

[0018] Soil pretreatment unit: includes a soil cleaning module (103) and a soil rotary tillage unit (102). The soil cleaning module (103) is used to remove gravel, weeds and other impurities from the surface of saline-alkali land. The soil rotary tillage unit (102) is used to loosen the surface soil by rotary tillage. The rotary tillage depth is 18cm, and the rotary tillage blade speed is matched with the equipment forward speed at 300r / min: 1.2m / s.

[0019] The isolation layer laying unit includes a trenching module (301), an impermeable isolation membrane (302), a stab-resistant non-woven protective layer (303), and a traction power unit (101). The trenching module (301) is pulled forward by the traction power unit (101) to dig a trench with a depth of 45cm in the rotary tilled soil. The lower stab-resistant non-woven protective layer (303), the impermeable isolation membrane (302 / 907) made of 0.6mm-1.5mm HDPE geomembrane, and the upper stab-resistant non-woven protective layer (303) are laid in sequence in the trench to form a three-layer composite isolation structure. The core operating components of this unit include a U-shaped soil plow (903), a serrated plow tip (912), a plow depth control adjustment wheel (913), a front-mounted cutting disc (911), a plow roller soil conveyor (901), a plow conveyor vibration platform (905), a spraying system (906), a chain-driven roller (908, which also has the functions of membrane release and tension adjustment), and an HDPE membrane field ridge laying wheel (909). All components work together to achieve integrated operation of "layer isolation - improvement and recovery - closed-loop sealing".

[0020] Permeable blind pipe laying system (916): It moves synchronously with the isolation layer laying unit (301) and directly lays the permeable blind pipe (915) on the impermeable isolation membrane (302 / 907) made of HDPE geomembrane through mechanical transmission, and then is automatically backfilled and buried by soil; the permeable blind pipe (915) is connected to the field ridge drainage system (914), which can collect the water accumulated in the cultivated layer and discharge it through the field ridge drainage system (914), while delivering air to the soil of the planting layer, ensuring oxygen absorption by plant roots, promoting plant growth, and improving soil microbial activity and soil looseness.

[0021] Soil desalination unit: The unit uses a leaching desalination module. Desalinated water is sprayed onto the topsoil after rotary tillage through a spraying device to dissolve the soluble salts in the soil. The salts seep down through the soil pores with the leaching water, are blocked by the isolation layer, and are discharged through the drainage pipe.

[0022] Soil amendment addition unit (401): used to uniformly add composite amendment to desalinated soil. The composite amendment is mixed in the proportion of 30% desulfurized gypsum, 25% humic acid, 20% biochar and 25% zeolite. The addition amount is 5% of the dry weight of the soil. The desalination time is controlled at 30s / ㎡ to ensure that the soil salt content is reduced to 0.15% after desalination.

[0023] Soil backfilling and leveling unit (501): Used to screen and mix the soil after adding the compound amendment, and then backfill it above the isolation layer and permeable blind pipe (915) to form a 15-40cm thick regenerated tillage layer (601).

[0024] Irrigation and fertilization unit: includes drip irrigation / micro-irrigation network (802), main water pipe, and fertilizer tank (803). The drip irrigation / micro-irrigation network (802) is laid in parallel within the regenerated tillage layer (601) and connects the main water pipe to the fertilizer tank (803). The fertilizer tank (803) contains fish protein compound enzyme fertilizer (molecular weight ≤500Da), which is diluted 1:800 and applied through drip irrigation via the network.

[0025] Monitoring unit: includes monitoring sensors (902) and data acquisition terminal. The monitoring sensors (902) are evenly distributed within the regenerated tillage layer (601) (every 10m). 2 One device is set up to monitor soil salinity, pH value, water content, nutrient content and heavy metal content in real time. The data is transmitted to the background for analysis and control through the acquisition terminal, and is linked with the water and fertilizer integration system to achieve precise control.

[0026] Auxiliary structure: The treatment area is divided into multiple rectangular independent planting plots (approximately 50m long × 7m wide). The plots are separated by isolation ridges (702) containing 15-20% quicklime. The boundary between the ridges and the regenerated arable layer (601) is compacted and sealed to prevent lateral seepage and cross-migration of salt. Drainage systems (914) are installed on the ridges to form a complete drainage network with permeable blind pipes (915).

[0027] (II) Principles of Isolation Layer Laying and Cooperative Operation Sequence

[0028] Core laying principle: Soil stratification and improvement and backfilling principle: Based on the "integrated design of stratification isolation and improvement and backfilling", through the coordinated movement of traction power and soil working mechanism, the front cutting disc (911) vertically cuts the soil to form a neat trench wall, reducing the working resistance of the main plow body and ensuring that the trench wall / field ridge wall is smooth and neat; the depth control adjustment wheel (913) adjusts the depth, and the U-shaped soil plow blade (903) and the serrated plow blade tip (912) move forward with the equipment and are inserted into the soil (preset depth 30-40cm, suitable for the laying standard of the barrier layer of saline-alkali land). The serrated plow blade tip (912) reduces soil resistance and accurately separates the compacted soil along the preset depth; the tail of the plow blade is set with a 30°-45° tilt angle (904) to adapt to the soil mechanical properties, ensuring that the shoveling process is stable and without excessive disturbance, raising the soil and dividing it into upper and lower layers, reserving an intermediate channel for the subsequent laying of the isolation film. To reduce soil resistance, a roller conveyor (910) is installed at 2 / 3 of the plow blade. The upper soil layer is transported through a conveying and vibrating platform (905). The platform has both conveying and vibrating functions (vibration frequency 5-8Hz), which can efficiently transfer the shoveled soil and break up soil clumps. At the same time, the spraying system (906) mixes organic fertilizer and saline-alkali soil conditioner into the moving soil. Based on the dynamic mixing principle, the conditioner and soil particles are evenly integrated. The improved soil falls back onto the surface covered with a separating membrane (302 / 907) and a permeable blind pipe (915) to form a plant planting layer with a thickness of ≥30cm.

[0029] HDPE membrane laying principle: Based on the design of "uniform speed adaptation - tension self-adaptation - closed-loop isolation", the release power of the membrane is provided by the chain-driven roller (908, which also has the functions of membrane release and tension adjustment). Through uniform delivery movement matched with the equipment traction speed (0.8-1.2m / s), it ensures that the 0.6mm-1.5mm specification HDPE membrane (with a life of more than 50 years) is laid flat between the upper and lower soil layers. The core isolation function of blocking the migration of salt and alkali components is achieved by utilizing the density of the membrane. During the laying process, the roller (908) adjusts the release speed and maintains the HDPE membrane with a 1.5% expansion and contraction relaxation based on the tension compensation principle. This copes with the stress caused by changes in soil topography, prevents the HDPE membrane from being damaged, and ensures the integrity of the isolation layer. Meanwhile, the HDPE film field ridge laying wheel (909) configured in the soil isolation layer laying unit (301) shapes the reserved part (reserved length 50cm) at both ends of the film body with a pressing angle of 15°-25° based on the field ridge contour adaptation principle, adapting it to the trapezoidal field ridge cross section with a top width of 30cm and a height of 20-40cm, so that it tightly covers the field ridge surface and compacts it, forming a closed isolation loop in the whole area, blocking the horizontal and vertical migration paths of salt in space.

[0030] The principle of synchronous laying of permeable blind pipes: The permeable blind pipe laying system (916) and the isolation layer laying unit (301) are linked by mechanical transmission to maintain the same laying speed as the equipment traction speed (0.8-1.2m / s). After the HDPE membrane (302 / 907) is laid, the permeable blind pipe (915) is laid on the membrane surface at a preset spacing (to meet the drainage needs of the planting field) to ensure that the blind pipe is tightly attached to the membrane. Then, the automatic burial is achieved through the synchronous operation of the soil backfilling and leveling unit (501) without the need for additional procedures, thus ensuring work efficiency.

[0031] Collaborative operation timing (error of each timing node ≤ ±0.3s)

[0032] Traction start-up sequence (T0 time): The traction power unit (101) starts and maintains a constant speed of 0.8-1.2m / s, and synchronously triggers the overall operation procedure of the soil isolation layer laying unit (301) and the permeable blind pipe laying system (916);

[0033] Soil stratification sequence (T0+0.5s): The front cutting disc (911) and the plow depth control adjustment wheel (913) start to run. The U-shaped soil plow (903) moves forward with the equipment and inserts into the soil to the preset depth. The horizontal cutting of the soil cross section and the separation of the upper and lower layers are completed by the tail tilt angle (904). The isolation membrane and the permeable blind pipe laying channel are reserved.

[0034] Membrane laying sequence (T0+1s): The chain-driven roller (908, which also has the functions of membrane release and tension adjustment) is started to deliver 0.6mm-1.5mm HDPE membrane at a uniform speed matched with the traction speed. At the same time, the release speed is adjusted to maintain the membrane's 1.5% stretch slack, so as to achieve flat laying of the membrane.

[0035] Permeable blind pipe laying sequence (T0+1.2s): The permeable blind pipe laying system (916) starts the mechanical transmission mechanism to simultaneously lay the permeable blind pipe (915) on the already laid and leveled HDPE membrane (302 / 907) surface, ensuring that the blind pipe is laid straight and the spacing is uniform;

[0036] Soil transfer and improvement sequence (T0+1.5s): The conveyor vibration platform (905) starts the vibration function, receives the soil shoveled from the upper layer and breaks up the clumps, and simultaneously triggers the spraying system (906) to spray organic fertilizer and saline-alkali soil conditioner in a quantitative manner to complete dynamic mixing;

[0037] Improved soil backfilling sequence (T0+3s): The improved soil falls along the end of the conveyor vibration platform (905) and evenly covers the laid isolation membrane (302 / 907) and permeable blind pipe (915) to form a plant planting layer with a thickness of ≥30cm.

[0038] Field ridge closed-loop sequence (T0+5s): The HDPE membrane field ridge laying wheel (909) is activated to compress and shape the reserved portions at both ends of the membrane, completing the compaction and sealing of the membrane with the field ridge, forming a closed-loop isolation throughout the entire area; at the same time, the permeable blind pipe (915) is connected to the field ridge drainage system (914). The above sequence ensures integrated continuous operation of "layering-membrane laying-pipe laying-improvement-recovery-closed-loop", without process interruption, ensuring the quality of the isolation layer and permeable blind pipe laying and the efficiency of operation.

[0039] (III) Improved Method The method described in this invention includes the following steps:

[0040] Soil pretreatment: Remove impurities from the surface of saline-alkali land by soil cleaning module (103), start soil rotary tillage unit (102) to loosen the surface soil by rotary tillage to a depth of 18cm; Co-laying of isolation layer and permeable blind pipe: Start traction power unit (101) to drive trenching module (301) and each working component to work in the preset sequence, dig trenches to a depth of 45cm, and lay the lower stab-proof non-woven protective layer (303), 0.6mm-1.5mm HDPE impermeable isolation membrane (302), and upper stab-proof non-woven protective layer (303) in sequence; Simultaneously start permeable blind pipe laying system (916) to lay permeable blind pipe (915) on HDPE impermeable isolation membrane (302 / 907) and connect it with field ridge drainage system (914) to complete soil stratification, improvement and backfilling and field ridge closed-loop sealing, forming a complete isolation and drainage system;

[0041] Soil desalination: Activate the leaching desalination module to spray desalinated water onto the surface soil for leaching desalination. The desalination time is 30 seconds / m², ensuring that the soil salt content is reduced to 0.15%.

[0042] Soil improvement and backfilling: The compound amendment is evenly added to the desalinated soil through the soil amendment addition unit (401). After mixing, it is screened by the soil backfilling and leveling unit (501) and backfilled above the isolation layer and permeable blind pipe (915). The soil is leveled to form a 15-40cm thick regenerated tillage layer (601) and the soil aggregate structure is cultivated simultaneously.

[0043] Irrigation and fertilization system layout: Drip irrigation / micro-irrigation network (802) is laid parallel within the regenerated tillage layer (601), connecting the main water pipe to the fertilizer tank (803), and monitoring sensors (902) are installed; Post-operation and maintenance: Diluted fish protein compound enzyme fertilizer is applied once a week through the drip irrigation / micro-irrigation network (802), with each irrigation volume being 20m³. 3 / mu, while monitoring the soil condition in real time through the monitoring unit and dynamically adjusting irrigation and fertilization parameters; during rainstorms or waterlogging periods, the waterlogged layer is drained through the permeable blind pipe (915) and the field ridge drainage system (914) to continuously ensure soil permeability and root growth environment, forming a closed loop of "treatment-maintenance-increase production".

[0044] (iv) Explanation of core innovations, creativity, and practicality: Core innovations (not covered by existing technologies).

[0045] The first integrated process of "non-excavation in-situ membrane laying + synchronous pipe laying" (soil separation unit + isolation layer laying unit + permeable blind pipe laying system + backfilling unit working together) was created, realizing the synchronous construction of a continuous physical barrier and drainage and ventilation system under the plow layer. It is different from the traditional manual excavation and step-by-step operation mode. No similar automated operation technology was found at home and abroad.

[0046] For the first time, the entire process of "physical isolation + permeable drainage + soil improvement + field division + water and fertilizer maintenance" is integrated into a single set of equipment, which solves the pain points of existing technologies such as step-by-step operation, low efficiency and water accumulation risks. The technology integration method is unique.

[0047] The permeable blind pipe (915) has both drainage and ventilation functions, breaking through the limitations of traditional drainage systems that only focus on draining accumulated water. It simultaneously improves soil permeability and microbial activity, and works in synergy with drip irrigation / micro-irrigation technology and fish protein compound enzyme fertilizer (molecular weight ≤500Da) to form a closed loop of "treatment-maintenance-yield increase", taking into account both the improvement effect and the crop growth needs.

[0048] The combination of technical features is non-conflicting: the connection relationship and operation logic of each unit (traction power, separation, film laying, pipe laying, improvement, irrigation, etc.) are new technologies with no completely identical combination methods in existing agricultural machinery and soil management technologies.

[0049] Creativity (possessing prominent substantive characteristics and significant progress)

[0050] Overcoming existing technological bottlenecks: Addressing the core pain points of traditional physical isolation methods such as "easily damaged membranes, low construction efficiency, and difficulty in draining accumulated water," topsoil methods such as "high costs and secondary pollution," and bioremediation methods such as "long cycles," an integrated solution is proposed, with a groundbreaking technical approach; the design of quicklime field ridges (15-20% content) and independent fields solves the problem of lateral salt migration, and the permeable blind pipes and field ridge drainage system work together to solve the risk of water accumulation, while avoiding the quality problems of traditional geomembrane welding, which is a "non-obvious" technical improvement.

[0051] The technological effects are significantly superior to existing technologies: the treatment cycle is shortened by more than 80% compared to traditional technologies (effective in the same year of treatment), crop yield is increased by 30-50%, water is saved by more than 60%, and the absorption rate of fish protein compound enzyme fertilizer reaches 90%; the aeration function of the permeable blind pipe increases soil microbial activity by more than 25% and improves soil looseness by 30%, and the synergistic effect of the technology exceeds the expectations of conventional technology combinations; the combination of 0.6mm-1.5mm HDPE geomembrane with a lifespan of more than 50 years (laid at a depth of 40-50cm), permeable blind pipe drainage and aeration system and soil aggregate structure cultivation technology achieves "permanent isolation + drainage and aeration + long-term fertility improvement", breaking through the limitations of existing technologies such as easy rebound of effects and poor soil permeability.

[0052] Practicality (clear industrial application value, feasible for large-scale implementation)

[0053] High technical feasibility: Each component (tractor with traction power, 0.6mm-1.5mm HDPE geomembrane, permeable blind pipe, vibrating screen, drip irrigation network, etc.) are existing mature industrial / agricultural parts. The technical solution is formed only through innovative combination and process optimization. There are no unachievable process or material problems. The operation process is standardized (pretreatment → separation → membrane laying → pipe laying → improvement → backfilling → field ridge → water and fertilizer application), which is suitable for large-scale mechanized operation and can be adapted to different areas of saline-alkali land and heavy metal contaminated land remediation scenarios.

[0054] Significant economic and ecological benefits: It avoids the high transportation costs of soil replacement, and the total life cycle cost is lower than that of traditional technologies. Drip irrigation saves water, fertilizers are absorbed efficiently, and the drainage system operates with low energy consumption, further reducing investment. It can restore the productivity of abandoned land and alleviate the shortage of arable land resources.

[0055] Leading in technological integration: Existing technologies are mostly single-function (only improvement or only drainage), while this invention integrates "7 core functions + 1 monitoring system + 1 drainage and ventilation system", with a level of automation and operational efficiency far exceeding similar technologies; the monitoring and control system (real-time monitoring of soil moisture, salinity, and heavy metal content) is linked with the water and fertilizer integration and drainage system to achieve precise regulation, which is in line with the development trend of "data-driven and controllable" in modern agriculture.

[0056] Technical indicators surpass industry standards: key indicators such as geomembrane life (50+ years), soil improvement cycle (effective in 1 month), crop yield increase (30-50%), and soil permeability improvement (25%+) are all superior to existing saline-alkali land treatment technologies (conventional improvement cycle 1-3 years, yield increase 10-20%). The application of fish protein compound enzyme fertilizer (molecular weight ≤500Da) increases the absorption rate by more than 40% compared to traditional chemical fertilizers and ordinary organic fertilizers, and has no chemical residues, meeting the needs of green agricultural development. Attached Figure Description

[0057] Figure 1 The unit composition and workflow diagram of the system of this invention;

[0058] Figure 2 A cross-sectional diagram of the independently cultivated plots after treatment;

[0059] Figure 3 A bird's-eye view of the field layout, water and fertilizer pipeline network, and permeable blind pipe distribution in the treatment area;

[0060] Figure 4 Schematic diagram of the integrated water and fertilizer irrigation unit;

[0061] Figure 5 Schematic diagram of the principle of co-laying of isolation layer and permeable blind pipe;

[0062] Figure 6 Schematic diagram of serrated plow blades and depth control wheel assembly;

[0063] Figure 7 Schematic diagram of the connection between the permeable blind pipe and the field ridge drainage system.

[0064] In the diagram: 101-Traction power unit, 102-Soil rotary tillage unit, 103-Soil cleaning module, 301-Treating module, 302-Imperible isolation membrane (0.6mm-1.5mm HDPE material, lifespan over 50 years), 303-Stab-resistant non-woven protective layer, 401-Soil conditioner addition unit, 501-Soil backfilling and leveling unit, 601-Reconstructed topsoil, 702-Isolation field ridge (containing 15-20% quicklime), 802-Drip irrigation / micro-irrigation network, 803-Fertilizer tank (built-in fish protein compound enzyme fertilizer, molecular weight ≤500Da), 902-Monitoring transmitter. Sensors (monitoring salt content, pH value, water content, nutrient and heavy metal content), 903-U-shaped soil plow blade, 904-plow blade tail tilt angle, 905-conveying vibration platform, 906-spraying system, 907-isolating membrane, 908-chain-driven roller (with membrane release and tension adjustment functions), 909-HDPE membrane field ridge laying wheel, 910-roller type soil vibration conveyor belt, 911-front cutting disc, 912-serrated plow blade tip, 913-plow blade depth control adjustment wheel, 914-field ridge drainage system, 915-permeable blind pipe, 916-permeable blind pipe laying system. Detailed Implementation

[0065] The present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments.

[0066] Preferred embodiment

[0067] Soil pretreatment: Start the soil cleaning module (103) to remove surface gravel and weeds, and the soil rotary tillage unit (102) loosens the top 18cm of soil by rotary tillage at a rotary blade speed of 300r / min and a forward speed of 1.2m / s.

[0068] The isolation layer and permeable blind pipe are laid in tandem: The traction power unit (101) is started, and the travel speed is set to 1.0 m / s, driving the trenching module (301) to dig a trench with a depth of 45 cm; each working component is started in the preset sequence: the U-shaped soil plow (903) is inserted into the soil to a depth of 35 cm, and the soil is layered by tilting the tail at a 35° angle; the chain-driven roller (908, which also has the function of membrane release and tension adjustment) releases 0.6 mm-1.5 mm HDPE membrane (with a life of more than 50 years), while adjusting the release speed to maintain the membrane's 1.5% stretch slack, and simultaneously laying the puncture-resistant non-woven protective layer (303) and the impermeable isolation membrane (302). 1. Apply a puncture-resistant nonwoven protective layer (303); 2. At T0+1.2s, the permeable blind pipe laying system (916) is activated, and the permeable blind pipes (915) are laid on the surface of the HDPE membrane (302 / 907) at a spacing of 5m, and connected to the field ridge drainage system (914); 3. The conveying vibration platform (905) vibrates at a frequency of 6Hz, and the spraying system (906) sprays the amendment at the same time, and the improved soil is back-covered to form a 35cm thick planting layer; 4. The HDPE membrane field ridge laying wheel (909) treats the 50cm reserved part at both ends of the membrane body at a 20° forming angle, adapts to the trapezoidal field ridge (containing 15-20% quicklime) with a top width of 30cm and a height of 30cm, and completes the closed-loop sealing;

[0069] Soil desalination: Desalinated water is sprayed through a rinsing desalination module, and the desalination time is controlled at 30s / ㎡. After desalination, the soil salt content is reduced to 0.15%.

[0070] Soil improvement and backfilling: According to the addition amount of 5% of the dry weight of the soil, the compound amendment (30% desulfurized gypsum, 25% humic acid, 20% biochar, and 25% zeolite) is evenly added to the desalinated soil through the soil amendment addition unit (401). After mixing, it is screened and backfilled through the soil backfilling and leveling unit (501), and leveled to form a 30cm thick regenerated tillage layer (601), while simultaneously cultivating the soil aggregate structure.

[0071] System Layout: The treatment area is divided into independent planting plots of 50m long × 7m wide. Isolation ridges (702) containing 15% quicklime are set between the plots and compacted and sealed. Drip irrigation / micro-irrigation networks (802) are laid in parallel within the plots, connecting the main water pipe to the fertilizer tank (803). Every 10m 2 Deploy one monitoring sensor (902);

[0072] Post-treatment maintenance: Dilute the fish protein compound enzyme fertilizer with a molecular weight of 300 Da (≤500 Da) at a ratio of 1:800, and irrigate once a week through the drip / micro-irrigation network (802), with an irrigation volume of 20m³ each time. 3 / mu (water saving of more than 60%); real-time monitoring of soil salinity, pH value, water content, nutrient content and heavy metal content through monitoring sensors (902), and dynamic adjustment of parameters; during the rainy season, water accumulation is discharged through permeable blind pipes (915) and field ridge drainage system (914) to ensure soil permeability.

[0073] Through this example, within one month after treatment, the soil salinity stabilized below 0.1%, the pH value stabilized between 6.5 and 7.5, the soil organic matter content increased by 40%, the soil microbial activity increased by more than 25%, and the wheat yield per mu reached more than 450 kg in the same year, which is 35-50% higher than the traditional improvement technology. The absorption rate of fish protein compound enzyme fertilizer reached 90%. The improvement effect is significant and stable in the long term, and the total life cycle cost is lower than the traditional soil replacement technology.

[0074] Beneficial effects

[0075] This invention completely blocks the migration of water and salt between the upper and lower soil layers and laterally through a three-layer composite isolation structure and a full-area closed-loop sealing design. Combined with a permeable blind pipe laying system (916) and a field ridge drainage system (914), it simultaneously solves the problems of water accumulation and soil permeability. It fundamentally solves the problems of incomplete blocking, easy rebound of effects, and poor soil aeration in existing technologies, and the improvement effect is stable in the long term.

[0076] The method employs in-situ leaching desalination + compound soil conditioner + dynamic mixing technology, which has high desalination efficiency and can simultaneously improve soil structure and enhance soil fertility, avoiding the limitations of single soil conditioners. After desalination, the soil salt content is stabilized below 0.1% and the pH value is maintained between 6.5 and 7.5.

[0077] By integrating drip irrigation / micro-irrigation technology with fish protein compound enzyme fertilizer, precise nutrient supply is achieved, crop absorption efficiency is improved, soil organic matter content is increased by 40%, and wheat yield per mu in the same year reaches more than 450 kg, which is 35% higher than traditional improvement technology (up to 50%). The aeration function of the permeable blind pipe promotes plant root development and microbial activity, further improving crop yield and soil sustainability.

[0078] The system has a high degree of integration and achieves mechanized continuous operation of "layering-film laying-pipe laying-improvement-recovery-closed loop" through time-sequential collaborative control, replacing manual excavation and laying. It is easy to operate, has high work efficiency (the average daily working area is increased to more than 1.5 hectares), low water consumption (water saving of more than 60%), and controllable cost. It is suitable for the improvement of different types and degrees of saline-alkali land, and solves the problem that existing technologies are not suitable for large-scale promotion. It has broad application prospects.

[0079] The design of quicklime field ridges and independent plots, the linkage between the monitoring system and the integrated water and fertilizer system and the drainage system further enhance the barrier effect and the ability to precisely regulate, achieving the full-cycle governance goal of "permanent isolation + drainage and aeration + long-term fertility improvement + data-driven operation and maintenance".

Claims

1. A system and method for constructing a physical isolation layer and recreating an in-situ topsoil layer in saline-alkali land, characterized in that: The system includes a soil pretreatment unit, an isolation layer laying unit, a soil desalination unit, a soil conditioner addition unit (401), a soil backfilling and leveling unit (501), an irrigation and fertilization unit, a monitoring unit, and a permeable blind pipe laying system (916); the soil pretreatment unit includes a soil cleaning module (103) and a soil rotary tillage unit (102); the isolation layer laying unit includes a traction power unit (101), a front-mounted cutting disc (911), a grooving module (301), an impermeable isolation membrane (302), a puncture-resistant non-woven protective layer (303), a U-shaped soil plow blade (903), a serrated plow blade tip (912), a plow blade depth limiting wheel (913), a transmission vibration platform (905), a spraying system (906), and a chain-driven roller (908). The system combines membrane release and tension regulation functions with HDPE membrane field ridge laying wheels (909) to form an integrated operation structure of "layered isolation - improved recovery - closed-loop sealing"; the permeable blind pipe laying system (916) moves synchronously with the isolation layer laying unit (301), and lays the permeable blind pipe (915) on the impermeable isolation membrane (302 / 907) through mechanical transmission, and the permeable blind pipe (915) is connected to the field ridge drainage system (914); the irrigation and fertilization unit includes drip irrigation / micro irrigation network (802), main water pipe and fertilizer tank (803); the monitoring unit includes monitoring sensor (902) and data acquisition terminal; the treatment area is divided into multiple independent planting plots, and the plots are separated by isolation field ridges (702) containing 15-20% quicklime.

2. The system according to claim 1, characterized in that: The rotary tillage unit (102) has a tillage depth of 18cm, and the rotary tillage blade speed is matched with the equipment forward speed at 300r / min: 1.2m / s; the impermeable isolation membrane (302) is made of 0.6mm-1.5mm HDPE geomembrane with a lifespan of more than 50 years and a laying depth of 45cm; the puncture-resistant non-woven protective layer (303) is divided into upper and lower layers, which are respectively attached to the upper and lower surfaces of the impermeable isolation membrane (302); the laying speed of the permeable blind pipe laying system (916) is consistent with the travel speed (0.8-1.2m / s) of the traction power unit (101), and the permeable blind pipe (915) is automatically backfilled and buried by the soil.

3. The system according to claim 1, characterized in that: The front cutting disc (911) vertically cuts the soil to form neat trench walls; the U-shaped soil plow (903) is pulled or pushed, and the serrated plow blade tip (912) is inserted into the soil to a preset depth of 30-45cm, with a tail tilt angle (904) of 30°-45°. A roller-type soil vibration conveyor belt (910) is added at 2 / 3 of the plow blade, and depth control adjustment wheels (913) are set on the left and right sides of the plow blade; the vibration frequency of the transmission vibration platform (905) is 5-8Hz; the release speed of the chain-driven roller (908) can be adjusted to maintain the HDPE film's stretching slack of 1.5%; the HDPE film field ridge laying wheel (909) has a pressing angle of 15°-25°, which is suitable for trapezoidal field ridges with a top width of 30cm and a height of 20-40cm, and the film body has a reserved length of 50cm at both ends.

4. The system according to claim 1, characterized in that: The soil conditioner addition unit (401) applies a compound conditioner mixed in the proportion of 30% desulfurized gypsum, 25% humic acid, 20% biochar, and 25% zeolite, with an addition amount of 5% of the dry weight of the soil; the fertilizer tank (803) contains fish protein compound enzyme fertilizer with a molecular weight ≤500 Da, which is diluted 1:800 and applied through the drip irrigation / micro-irrigation network (802); the permeable blind pipe (915) has the functions of collecting and draining water accumulated in the cultivated layer and aerating the soil.

5. The system according to claim 1, characterized in that: The monitoring sensor (902) is used every 10m 2 One unit is set up to monitor soil salinity, pH value, water content, nutrient content and heavy metal content in real time, and to achieve precise control with the integrated water and fertilizer irrigation unit (801); the isolation field ridge (702) contains 15-20% quicklime and is compacted and sealed at the junction with the regenerated tillage layer (601); the field ridge drainage system (914) and the permeable blind pipe (915) form a complete drainage network.

6. A method for constructing a physical isolation layer and recreating an in-situ topsoil layer in saline-alkali land, characterized in that: Includes the following steps: (1) Soil pretreatment: Impurities are removed by the soil cleaning module (103), and the soil rotary tillage unit (102) loosens the surface soil by rotary tillage; (2) Coordinated laying of isolation layer and permeable blind pipe: Start the traction power unit (101) to drive the trenching module (301) and each working component to work in the preset sequence, excavate a trench with a depth of 45cm, and lay the lower stab-proof non-woven protective layer (303), 0.6mm-1.5mm HDPE geomembrane (302), and upper stab-proof non-woven protective layer (303) in sequence; at the same time, start the permeable blind pipe laying system (916) to lay the permeable blind pipe (915). The soil is layered, improved and backfilled, and the field ridges are sealed on the HDPE geomembrane (302 / 907) and connected to the field ridge drainage system (914). The timing sequence is as follows: traction or pushing start at T0, soil layering at T0+0.5s, membrane laying at T0+1s, permeable blind pipe laying at T0+1.2s, soil transfer and improvement at T0+1.5s, improved soil backfilling at T0+3s, and field ridge sealing at T0+5s. The error of each timing node is ≤±0.3s. (3) Soil desalination: Desalinated water is sprayed through the rinsing desalination module, with a desalination time of 30s / ㎡. After desalination, the soil salt content is reduced to 0.15%. (4) Soil improvement and backfilling: Add compound soil conditioner and mix it. After sieving, backfill it above the isolation layer and permeable blind pipe (915), level it to form a 15-40cm thick regenerated tillage layer (601), and cultivate soil aggregate structure at the same time. (5) Layout of irrigation and fertilization system: Lay drip irrigation / micro irrigation network (802), connect the main water pipe to the fertilizer tank (803), and install monitoring sensors (902); (6) Post-operation and maintenance: Diluted fish protein compound enzyme fertilizer is applied through drip irrigation / micro-irrigation network (802), soil conditions are monitored in real time and parameters are dynamically adjusted. During rainstorms or waterlogging periods, drainage is carried out in conjunction with field ridge drainage system (914) through permeable blind pipe (915) to form a closed loop of "treatment-maintenance-yield increase".

7. The method according to claim 6, characterized in that: In step (2), the traction power unit (101) travels at a speed of 0.8-1.2 m / s, and the chain-driven roller (908) delivers 0.6 mm-1.5 mm HDPE film at a uniform speed and adjusts the release speed; the permeable blind pipe (915) is laid at a spacing of 5 m and is tightly connected to the field ridge drainage system (914); in step (4), the thickness of the regenerated topsoil layer (601) is 30 cm; in step (6), the fish protein compound enzyme fertilizer is diluted at a ratio of 1:800, the drip irrigation frequency is once a week, and the irrigation volume is 20 m³ each time. 3 / mu, saving more than 60% of water.

8. The method according to claim 6, characterized in that: The treatment cycle is shortened by more than 80% compared with traditional technologies, and the effect can be seen in the same year. After treatment, the soil salinity is stabilized below 0.1%, the pH value is stabilized between 6.5 and 7.5, the soil organic matter content is increased by 40%, the soil microbial activity is increased by more than 25%, the crop yield is increased by 30-50%, and the absorption rate of fish protein compound enzyme fertilizer reaches 90%.

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