Method for improving moderately salinized soil in facility farmland by crop rotation and straw returning

Abstract

The application relates to the technical field of soil improvement, and discloses a method for improving moderately salinized soil in facility farmland by means of crop rotation and straw field returning, which comprises the following steps: arranging monitoring points on a plough layer of the facility farmland, collecting the conductivity state, the soil volume water content state and the soil temperature state; arranging deep-rooted crops and shallow-rooted crops in rotation on the facility farmland determined as the moderately salinized soil; crushing the aboveground residues of the last crop in rotation in situ in the facility farmland; after the high-temperature and smothering treatment is finished, ventilating and dehumidifying the shed, then carrying out land preparation and ridging of the facility farmland, and planting the crops in rotation on the ridged cultivation beds to enter the next rotation cycle. The method avoids the interruption of the improvement caused by the fragmentation of operation stages or the inconsistent treatment time sequence through the arrangement of the crops in rotation, the in-situ crushing and returning of the straw, the application of the organic materials and microbial preparations, the rotary tillage and mixing, and the high-temperature and smothering treatment.

Description

Technical Field

[0001] This invention relates to the field of soil improvement technology, and in particular to a method for improving moderately salinized soil in facility agriculture land through crop rotation and straw return. Background Technology

[0002] Facility-based agricultural land refers to arable land used for crop production under facility conditions such as solar greenhouses and plastic sheds. It is characterized by high multiple cropping index, high input intensity, and continuous operation cycle. Due to the high degree of enclosure of the facility environment, concentrated irrigation methods, and large evaporation, salt in the topsoil of facility-based agricultural land is prone to accumulate under long-term continuous cropping conditions, thus forming salinized soils of varying degrees.

[0003] To address the problem of moderately salinized soil in facility-based agricultural land, existing technologies typically employ single or combined measures such as crop rotation, straw return to the field, application of organic materials, application of microbial agents, and high-temperature fumigation. Crop rotation is implemented by changing crop types; crop straw is shredded and returned to the field after harvest; well-rotted organic materials or microbial agents are applied to the soil before tillage; and under facility conditions, the soil is irrigated and covered with mulch for high-temperature fumigation. These technical solutions usually set up operational steps targeting single objectives such as soil salinity control, soil structure improvement, or pathogen suppression. Each treatment measure is often implemented independently in production management, and the execution sequence is mainly determined based on crop production arrangements or human experience.

[0004] However, the inventors of this application discovered in the process of realizing the technical solution of this application that the above-mentioned prior art has at least the following technical problems: In the existing measures for improving moderately salinized soil in facility agricultural land, there is a lack of unified process organization and fixed execution order among the various treatment links. Different improvement measures are often implemented in a decentralized manner, which can easily lead to inconsistent treatment sequences or interruptions in the improvement process. As a result, it is difficult to continuously and stably improve and control the distribution of salt in the topsoil and the state of soil structure under continuous production conditions. Summary of the Invention

[0005] To overcome the above shortcomings, this invention provides a method for improving moderately salinized soil in facility agriculture through crop rotation and straw return, aiming to address the problem that different improvement measures in the existing technology are often implemented in a scattered manner, which can easily lead to inconsistent treatment sequences or interruptions in the improvement process.

[0006] This invention provides the following technical solution: a method for improving moderately saline soil in facility agriculture through crop rotation and straw return, comprising the following steps: S1. Set up monitoring points in the cultivated layer of facility agricultural land to collect soil electrical conductivity, soil volumetric water content and soil temperature data, and determine the facility agricultural land as moderately saline soil based on the collected soil electrical conductivity data. S2. On facility agricultural land that is determined to be moderately saline soil, implement crop rotation between deep-rooted crops and shallow-rooted crops, or implement crop rotation between facility vegetable crops and grain crops to form a crop rotation sequence. S3. The above-ground residues of the previous crop rotation are crushed in situ within the facility farmland, and the crushed straw is evenly spread on the surface of the cultivated layer to form a straw layer. S4. Apply decomposed organic material onto the straw layer and simultaneously apply microbial agents to form a composite material layer of straw layer, organic material and microbial agents. S5. Rotary tillage is performed on the composite material layer and the original soil to mix straw, organic materials and microbial agents into the tillage layer to form an improved tillage layer. S6. Irrigate the improved tillage layer, then cover it with mulch and seal the greenhouse to carry out high-temperature fumigation treatment on the facility agricultural land. S7. During the high-temperature fumigation treatment, continuously collect soil electrical conductivity, soil volumetric water content and soil temperature, and perform water replenishment and ventilation dehumidification operations according to the changes in the states. S8. After the high-temperature fumigation treatment is completed, the greenhouse is ventilated and dehumidified. Then, the land for facility agriculture is prepared and ridged, and rotation crops are planted on the ridged cultivation beds to enter the next rotation cycle.

[0007] Preferably, in step S1, the step of determining that the facility agricultural land is moderately saline soil based on the collected soil electrical conductivity status includes: Multiple fixed monitoring points were set up along the crop planting rows and ridges within the facility agricultural land; At each monitoring point, the soil electrical conductivity, soil volumetric water content and soil temperature were collected. The collected data from each monitoring point are summarized and processed to form a soil condition dataset for S6 and S7 control.

[0008] Preferably, in step S2, the step of configuring deep-rooted crops and shallow-rooted crops for rotation, or configuring greenhouse vegetable crops and grain crops for rotation, to form a crop rotation sequence on facility agricultural land determined to be moderately saline soil, includes: The order of cropping deep-rooted crops and shallow-rooted crops should be determined according to the cultivation system of facility agriculture land. Within a crop rotation cycle, deep-rooted crops and shallow-rooted crops are planted sequentially on the same ridge. In the next crop rotation cycle, the crop types from the previous cycle will be swapped with those from the current cycle.

[0009] Preferably, in step S3, the step of evenly spreading the crushed straw on the surface of the tillage layer to form a straw layer includes: Leave the crop stalks on the ground after harvest; The stems are shredded in situ using a shredding device; Spread the chopped straw evenly along the direction of the planting ridges so that the straw covers the entire surface of the cultivated layer.

[0010] Preferably, in step S4, the step of simultaneously applying the microbial agent to form a composite material layer from the straw layer, organic material, and microbial agent includes: Evenly spread well-rotted organic materials on the surface of the straw layer; Microbial agents are applied to the straw layer by spreading or flushing with water while or after spreading the decomposed organic materials. This allows the microbial agents to be spatially interspersed with straw and decomposed organic materials.

[0011] Preferably, in step S5, the composite material layer and the original soil are subjected to rotary tillage to mix straw, organic materials, and microbial agents into the tillage layer, forming an improved tillage layer. Rotary tillage machinery is used to perform rotary tillage operations along the ridge direction on facility farmland; The straw layer, decomposed organic material, and microbial agents are all turned into the soil layer. Multiple cross-rotation tillage processes create a continuous mixed layer of the above materials within the tillage layer.

[0012] Preferably, in step S6, the step of irrigating the improved tillage layer, then covering it with mulch and sealing the greenhouse to implement high-temperature fumigation treatment for the facility agriculture land includes: After rotary tillage and mixing are completed, the facility farmland is irrigated to keep the entire topsoil moist. After irrigation, lay a plastic film to cover the soil surface; Close the vents in the greenhouse to create a sealed, stuffy environment inside.

[0013] Preferably, in step S7, the steps of performing water replenishment and ventilation / dehumidification operations based on the changes in the state include: During the high-temperature fumigation period, the soil electrical conductivity, soil volumetric water content, and soil temperature were periodically measured. When the soil volumetric moisture content deviates from the preset moisture range, water replenishment operations are performed. Ventilation and dehumidification operations are performed when the soil temperature or soil electrical conductivity deviates from the preset range. The system alternates between water replenishment and ventilation / dehumidification operations.

[0014] Preferably, in step S8, the steps of ventilating and dehumidifying the greenhouse, then preparing and ridging the land for agricultural use, and planting rotation crops on the ridged cultivation beds to enter the next rotation cycle include: Remove the mulch film after ventilation and dehumidification are complete; Leveling and ridging of the topsoil; Plant the crops on the formed ridges according to the order of crop rotation.

[0015] Preferably, in step S8, after the crop rotation crop completes one growth cycle, its above-ground parts are retained in the facility agricultural land and used as the treatment object for the straw in-situ crushing and returning to the field step in the next round S3, so that the crop rotation crop configuration step, the straw in-situ crushing and returning to the field step, the organic material and microbial agent application step, the rotary tillage and mixing step, the irrigation and humidity adjustment and high temperature fumigation step, and the state trigger control step are continuously and cyclically executed according to the crop rotation cycle.

[0016] The present invention has the following beneficial effects: 1. This invention organizes the steps of crop rotation configuration, in-situ straw crushing and returning to the field, application of organic materials and microbial agents, rotary tillage and mixing, high-temperature fumigation treatment, and land preparation and planting into a complete process in a fixed sequence, avoiding the interruption of improvement caused by the fragmentation of operation stages or inconsistent treatment sequence, which is conducive to maintaining the relative stability of salt distribution and structural state of the topsoil.

[0017] 2. During the high-temperature fumigation treatment stage, the present invention continuously collects soil electrical conductivity, soil volumetric water content and soil temperature, and performs water replenishment and ventilation dehumidification operations based on the changes in these states, so that the fumigation treatment process no longer relies solely on fixed times or human experience, thereby improving the controllability of the fumigation treatment.

[0018] 3. This invention introduces organic materials and microbial agents after in-situ crushing and returning straw to the field, and then forms an improved tillage layer through rotary tillage, allowing the straw returning process and cultivation preparation process to be completed in the same operational chain. This is beneficial for crop rotation crops to enter the growth stage according to the established cultivation system. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method for improving moderately salinized soil in facility agriculture land through crop rotation and straw return, as proposed in this invention. Figure 2 This is a dynamic change diagram of the volumetric water content of tomato soil at 10 cm and 30 cm depth throughout the entire growth period of the present invention. Figure 3 This is a dynamic change diagram of the electrical conductivity of tomato soil at 10 cm and 30 cm depths throughout the entire growth period of the present invention. Figure 4 The soil desalination rate and salt return rate are different measures of the present invention; Figure 5 This is a diagram showing the influencing factors of soil salinity at 10 cm and 30 cm depths, as presented in this invention. Figure 6 The diagram shows the effect of different control measures of the present invention on nutrient absorption in tomatoes. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0021] Example 1: Refer to Figure 1 This invention provides a method for improving moderately salinized soil in facility agriculture land through crop rotation and straw return, comprising the following steps: S1. Set up monitoring points in the cultivated layer of facility agricultural land to collect soil electrical conductivity, soil volumetric water content and soil temperature data, and determine the facility agricultural land as moderately saline soil based on the collected soil electrical conductivity data. S2. On facility agricultural land that is determined to be moderately saline soil, implement crop rotation between deep-rooted crops and shallow-rooted crops, or implement crop rotation between facility vegetable crops and grain crops to form a crop rotation sequence. S3. The above-ground residues of the previous crop rotation are crushed in situ within the facility farmland, and the crushed straw is evenly spread on the surface of the cultivated layer to form a straw layer. S4. Apply decomposed organic materials onto the straw layer and simultaneously apply microbial agents to form a composite material layer of straw layer, organic materials and microbial agents. S5. Rotary tillage is carried out on the composite material layer and the original soil to mix straw, organic materials and microbial agents into the tillage layer to form an improved tillage layer. S6. Irrigate the improved topsoil, then cover it with plastic film and seal the greenhouse. High-temperature fumigation treatment is carried out on the facility agricultural land. S7. During the high-temperature fumigation treatment, continuously collect soil electrical conductivity, soil volumetric water content and soil temperature, and perform water replenishment and ventilation dehumidification operations according to the changes in the status. S8. After the high-temperature fumigation treatment is completed, the greenhouse is ventilated and dehumidified. Then, the land for facility agriculture is prepared and ridged, and rotation crops are planted on the ridged cultivation beds to enter the next rotation cycle.

[0022] Specifically, this invention uses crop rotation cycles as the basic unit for method execution. Before the start of each crop rotation cycle, the state of the cultivated layer of the facility agricultural land is detected through step S1. Monitoring points are set within the cultivated layer, and the collected data on soil electrical conductivity, soil volumetric water content, and soil temperature constitute the basic data for judgment and control.

[0023] In S2, a crop rotation sequence is established based on the cultivation system of the facility farmland, allowing different root types or crop types to be rotated within the same facility farmland according to the cropping order. The determination of the crop rotation sequence is linked to the in-situ straw crushing and returning operation in step S3, ensuring that the residue from the previous crop directly serves as the subsequent treatment target. In S3, after the rotation crop is harvested, its above-ground residue is retained within the facility farmland and formed into a uniformly distributed straw layer through in-situ crushing. This straw layer covers the surface of the tillage layer, providing a carrier for the subsequent application of organic materials and microbial agents. In S4, decomposed organic materials and microbial agents are applied into the straw layer, forming a composite material layer in space. This composite material layer is mixed with the original soil during subsequent rotary tillage. In S5, the composite material layer is turned into the tillage layer through rotary tillage, creating a continuously distributed improved tillage layer of straw, organic materials, and microbial agents. This improved tillage layer serves as the treatment target for steps S6 and S7.

[0024] In step S6, after irrigating the improved topsoil, the greenhouse is covered with plastic film and sealed, putting the agricultural facility into a high-temperature fumigation state. The high-temperature fumigation treatment and the state monitoring and control operations in step S7 are performed continuously. In S7, soil state vectors are continuously collected during the high-temperature fumigation treatment, and water replenishment is performed based on changes in soil volumetric moisture content. Ventilation and dehumidification are performed based on changes in soil electrical conductivity and soil temperature. Water replenishment and ventilation / dehumidification are performed alternately during the high-temperature fumigation treatment. In step S8, after the high-temperature fumigation treatment ends, the greenhouse is ventilated and dehumidified, the plastic film is removed, the agricultural facility is prepared and ridged, and rotation crops are planted on the resulting cultivation beds. After the rotation crops enter their growth period, the newly formed above-ground residue at the end of their growth cycle is again treated as the object of step S3, thus allowing the method of this invention to be continuously executed according to the rotation cycle.

[0025] Furthermore, in step S1, the step of determining that the facility agricultural land is moderately saline soil based on the collected soil electrical conductivity data includes: Multiple fixed monitoring points were set up along the crop planting rows and ridges within the facility agricultural land; At each monitoring point, the soil electrical conductivity, soil volumetric water content and soil temperature were collected. The collected data from each monitoring point are summarized and processed to form a soil condition dataset for S6 and S7 control.

[0026] Specifically, fixed monitoring points are set up within the cultivated layer of the facility agriculture land. These points are spaced out along the crop planting rows and corresponding to adjacent rows, ensuring that the monitoring points cover the crop growth area on a planar surface. The location of each monitoring point remains unchanged within the same crop rotation cycle to guarantee spatial comparability of data collected at different times.

[0027] At each monitoring point, soil electrical conductivity, soil volumetric water content, and soil temperature were acquired according to a standardized data collection procedure. The data were recorded with time as the index to reflect the changes in the topsoil state at different operational stages. Throughout the data collection process, the parameters at each monitoring point remained consistent to avoid biases introduced by differences in collection methods.

[0028] To provide a unified representation of data from multiple monitoring points, data collected simultaneously from each monitoring point will be aggregated and processed. A total of n fixed monitoring points are set up within the facility agricultural land. At time t, the soil electrical conductivity, soil volumetric water content, and soil temperature collected from the i-th monitoring point are denoted as follows: , and Then, the overall state of agricultural land at that moment can be represented as: ; ; ; in, This represents the soil electrical conductivity state obtained at time t. This represents the soil volumetric water content state obtained at time t. This represents the soil temperature state summarized at time t; n represents the number of fixed monitoring points.

[0029] Through the above-described summarization process, a soil condition dataset characterizing the overall topsoil state of facility agricultural land is formed. This soil condition dataset is used in S1 to determine moderately saline soils, and in S6 and S7 as the control basis for irrigation treatment, high-temperature fumigation treatment, and water replenishment and ventilation / humidification operations.

[0030] The determination of moderately salinized soils is based on the aggregated soil electrical conductivity status. Proceed. When When the soil falls within the pre-defined moderate salinity assessment range, the facility farmland is determined to be moderately salinized soil, and the subsequent crop rotation and straw return improvement process begins. The assessment range can be set based on soil salinity grading standards or on-site testing results, and its specific value does not affect the implementation structure of S1.

[0031] By setting up multiple fixed monitoring points within the facility agricultural land and summarizing and processing the collected data, S1 can generate a soil state dataset that reflects the overall state of the topsoil of the facility agricultural land. This allows subsequent high-temperature fumigation treatment and state trigger control steps to be executed based on a unified data source, thereby ensuring that each operation step is implemented under the same state judgment system.

[0032] Furthermore, in step S2, the steps of implementing a crop rotation sequence by rotating deep-rooted crops with shallow-rooted crops, or rotating greenhouse vegetable crops with grain crops, on facility agricultural land determined to have moderately saline soil include: The order of cropping deep-rooted crops and shallow-rooted crops should be determined according to the cultivation system of facility agriculture land. Within a crop rotation cycle, deep-rooted crops and shallow-rooted crops are planted sequentially on the same ridge. In the next crop rotation cycle, the crop types from the previous cycle will be swapped with those from the current cycle.

[0033] Specifically, crop rotation sequences are established based on the cultivation system of protected agricultural land. Within the same protected agricultural land, crops suitable for rotation are classified according to root distribution characteristics or crop type. Crops with roots mainly distributed in the lower part of the tillage layer are classified as deep-rooted crops, while crops with roots mainly distributed in the upper part of the tillage layer are classified as shallow-rooted crops; alternatively, crops are classified as protected vegetable crops and grain crops. The establishment of crop rotation sequences is based on the classification results and corresponds to the production season and operational arrangements of protected agricultural land.

[0034] Within a crop rotation cycle, deep-rooted and shallow-rooted crops are planted sequentially on the same ridge in a predetermined order, allowing the same ridge to experience the growth process of crops with different root distribution levels during continuous cropping. The same ridge refers to the fixed cultivation bed position formed after land preparation and ridging, which remains unchanged within a crop rotation cycle, thus enabling different crops to share the same soil structure in space.

[0035] In the next crop rotation cycle, the crop types planted in the previous cycle are swapped with the crop types planned for the current cycle. That is, if a deep-rooted crop was planted on a ridge in the previous cycle, a shallow-rooted crop will be planted on that ridge in the next cycle, and vice versa; or if greenhouse vegetables were planted in the previous cycle, a grain crop will be planted on that ridge in the next cycle. This swapping arrangement ensures that the crop types on the same greenhouse farmland alternate in a predetermined order across different crop rotation cycles.

[0036] To formally describe the crop rotation sequence, let the rotation cycle be numbered k, and in the k-th rotation cycle, the crop type corresponding to the same ridge position is denoted as . Then, the crop types in adjacent crop rotation cycles satisfy the following correspondence: ; Where R() represents the crop type swapping mapping, when When it is a deep-rooted crop, It is a shallow-rooted crop; when When it is a shallow-rooted crop, It is a deep-rooted crop; or when When growing greenhouse vegetables, It is a food crop.

[0037] By using the above-mentioned crop rotation configuration method, the crop rotation sequence has clear execution rules in both time and space dimensions, and directly corresponds to the treatment object of in-situ straw crushing and returning to the field in step S3. This ensures that the crop residues formed after each crop rotation cycle can be used as input for the next processing step, realizing the continuous connection between the crop rotation configuration step and the subsequent straw returning and high-temperature fumigation treatment steps.

[0038] Furthermore, in step S3, the step of evenly spreading the crushed straw on the surface of the tillage layer to form a straw layer includes: Leave the crop stalks on the ground after harvest; The stems are shredded in situ using a shredding device; Spread the chopped straw evenly along the direction of the planting ridges so that the straw covers the entire surface of the cultivated layer.

[0039] Specifically, after harvesting the previous crop rotation, the above-ground stems are left within the facility farmland without being removed or piled up, ensuring direct contact between the stems and the topsoil. The retained stems are primarily distributed along the original planting rows, forming strips along the ridge direction. Subsequently, shredding equipment is used to shred the stems in situ along the ridge direction. During the shredding process, the equipment moves along the ridge direction, cutting the stems into smaller segments within their original distribution area, thus preventing concentrated accumulation or migration across ridges. After shredding, the straw remains largely distributed within its original ridge direction.

[0040] After in-situ chopping, the chopped straw is spread out to evenly distribute it along the planting ridges and cover the surface of the tillage layer. Spreading can be achieved through the scattering structure of the shredder itself or subsequent leveling operations, ensuring a continuous distribution of straw on the tillage surface, thus forming a straw layer. This straw layer serves as a support layer for the application of decomposed organic materials and microbial agents in step S4, and is also a component of the rotary tillage mixing layer in step S5.

[0041] To characterize the uniformity of straw application, the topsoil surface can be divided into several unit regions of equal area. At time t, the straw coverage area of ​​the j-th unit region is denoted as... The total area of ​​the unit region is denoted as The average coverage of the straw layer can be expressed as: ; in, This represents the average coverage of the straw layer on the surface of the cultivated layer at time t; Indicates the number of unit regions; This represents the area covered by straw within the j-th unit region; This represents the total area of ​​the unit region.

[0042] By directly crushing the crop in situ after harvest and spreading it evenly along the ridge, a continuous straw layer is formed on the surface of the tillage layer. This straw layer can serve as a uniform support for organic materials and microbial agents in subsequent steps, and is completely turned into the tillage layer during rotary tillage, thus ensuring the continuous connection between the straw return treatment process and subsequent improvement processes.

[0043] Furthermore, in step S4, the step of simultaneously applying the microbial agent to form a composite material layer from the straw layer, organic material, and microbial agent includes: Evenly spread well-rotted organic materials on the surface of the straw layer; Microbial agents are applied to the straw layer by spreading or flushing with water while or after spreading the decomposed organic materials. This allows the microbial agents to be spatially interspersed with straw and decomposed organic materials.

[0044] Specifically, after forming the straw layer in step S3, the straw layer is used directly as the application base, and the decomposed organic material is spread without turning it over. The decomposed organic material is spread along the planting ridge direction, so that it forms a continuous distribution on the surface of the straw layer, thereby ensuring that the organic material can maintain stable contact with the straw layer before subsequent rotary tillage operations.

[0045] After spreading the decomposed organic material, apply the microbial agent into the straw layer. The microbial agent can be applied directly to the surface of the straw layer or by combining it with the irrigation process, allowing it to penetrate into the straw layer through water flushing. Regardless of the application method, the microbial agent should be distributed between the straw layer and the decomposed organic material, covering the entire treatment area along the ridge direction.

[0046] After the decomposed organic material and microbial agents have been applied, the straw layer, organic material, and microbial agents form an alternating distribution structure in both the vertical and horizontal directions. The straw layer is located on the outermost side and is in contact with the surface of the tillage layer; the decomposed organic material is distributed on the surface of the straw layer and between the straw pores; and the microbial agents are dispersed in the spatial structure formed by the straw and organic material, thus forming a composite material layer for subsequent rotary tillage and mixing.

[0047] To characterize the spatial distribution of microbial agents in the composite material layer, the straw-covered area can be divided into several unit regions of equal area. At time t, the amount of microbial agents detected in the k-th unit region is denoted as... The average distribution level of microbial agents in the composite material layer can be expressed as: ; in, This represents the average distribution of microbial agents within the composite material layer at time t; This represents the distribution of microbial agents within the k-th unit region; q represents the number of cell regions.

[0048] After the straw layer is formed, decomposed organic materials and microbial agents are applied sequentially, and the three are arranged in a staggered composite material layer. This composite material layer can be turned into the tillage layer as a whole in the rotary tillage operation in the subsequent step S5, so that the straw, organic materials and microbial agents enter the improved tillage layer at the same time, thereby ensuring that the components of each material have a consistent distribution in the tillage layer during the subsequent high-temperature fumigation treatment.

[0049] Furthermore, in step S5, the composite material layer and the original soil are subjected to rotary tillage to mix straw, organic materials, and microbial agents into the tillage layer, forming an improved tillage layer. This step includes: Rotary tillage machinery is used to perform rotary tillage operations along the ridge direction on facility farmland; The straw layer, decomposed organic material, and microbial agents are all turned into the soil layer. Multiple cross-rotation tillage processes create a continuous mixed layer of the above materials within the tillage layer.

[0050] Specifically, after forming the composite material layer in step S4, no transfer or stratification of the surface material is performed; the location of the composite material layer is directly used as the rotary tillage area. The rotary tillage operation is carried out along the existing ridge direction, ensuring that the direction of travel of the rotary tillage machine is consistent with the direction of the planting ridge. This guarantees that the material is evenly turned over within the ridge direction during the rotary tillage process, avoiding inconsistent distribution caused by cross-ridge mixing.

[0051] During rotary tillage, the rotating parts of the rotary tiller turn the straw layer, decomposed organic matter, and microbial agents on the surface of the tillage layer into the original soil, mixing the composite material layer with the original soil. The tillage depth covers the thickness of the tillage layer, allowing the straw, organic matter, and microbial agents to penetrate the tillage layer and come into direct contact with the original soil. To improve mixing uniformity, after the first round of rotary tillage along the ridge direction, at least one more rotary tillage operation in an intersecting direction is performed. The intersecting direction forms an angle with the ridge direction, causing the materials to redistribute in both horizontal and vertical directions during rotary tillage, thus forming a continuously distributed mixed structure within the tillage layer. After multiple intersecting rotary tillages, the straw, organic matter, and microbial agents no longer exhibit a clear stratification within the tillage layer, forming an improved tillage layer.

[0052] To characterize the material distribution after rotary tillage and mixing, the topsoil can be divided into several units of equal volume. At time t, the first unit... The combined content of straw and organic matter detected within each unit is recorded as follows: The average value of this comprehensive content within the improved topsoil can be expressed as: ; in, This indicates the average distribution level of straw and organic matter in the improved topsoil at time t. Indicates the first The total content of straw and organic materials within each unit; Indicates the number of unit cells.

[0053] By rotary tillage along the ridges and combined with cross-rotary tillage, the composite material layer is turned into the tillage layer as a whole and forms a continuous mixed structure with the original soil. This creates an improved tillage layer for subsequent irrigation and humidity regulation, high-temperature fumigation treatment, and state triggering control steps, providing a unified physical basis for the implementation of subsequent steps within the same tillage layer.

[0054] Furthermore, in step S6, the improved topsoil is irrigated, then covered with mulch and the greenhouse is sealed. The steps of implementing high-temperature fumigation treatment on the facility agricultural land include: After rotary tillage and mixing are completed, the facility farmland is irrigated to keep the entire topsoil moist. After irrigation, lay a plastic film to cover the soil surface; Close the vents in the greenhouse to create a sealed, stuffy environment inside.

[0055] Specifically, after step S5 is completed and the improved tillage layer is formed, the structure of the tillage layer is kept undisturbed by mechanical means, and irrigation is directly applied to the facility farmland. Irrigation transforms the improved tillage layer from a loose state after rotary tillage to a generally moist state, allowing straw, organic materials, microbial agents, and the original soil to form a continuous contact interface under moisture conditions. The irrigation method can be flood irrigation, drip irrigation, or micro-sprinkler irrigation, depending on the irrigation conditions of the facility farmland. During irrigation, the entire treatment area is covered to ensure consistent moisture distribution within the tillage layer.

[0056] After irrigation, mulch film is laid on the surface of the farmland. The film is laid along the ridges and covers the improved topsoil layer, creating a continuous covering. During installation, the overlaps between adjacent films are compacted to minimize air exchange channels. Once the film is laid, the improved topsoil layer is covered. After installation, the ventilation openings and other openings of the greenhouse are closed, creating a sealed space. This seal restricts airflow and isolates the greenhouse environment from the outside, initiating the high-temperature fumigation process. This high-temperature fumigation is implemented based on irrigation and mulch covering, and is continuously integrated with the status acquisition and control process in step S7.

[0057] During the high-temperature greenhouse fumigation process, the heat inside the greenhouse mainly comes from the external environment and the heat released during the decomposition of organic matter within the improved tillage layer. To characterize the heat changes in the tillage layer during the fumigation stage, the average temperature state of the improved tillage layer can be defined at time t. The change process is described by the rate of change of temperature over time: ; in, This represents the temperature state of the improved topsoil layer collected at time t. This indicates the trend of soil temperature changes over time.

[0058] By sequentially implementing irrigation, mulching, and greenhouse sealing after rotary tillage and mixing, the improved tillage layer enters a high-temperature fumigation state under conditions of high moisture content and low air exchange. This provides a unified treatment environment for subsequent water replenishment and ventilation operations based on soil electrical conductivity, soil volumetric moisture content, and soil temperature.

[0059] Furthermore, in step S7, the steps of performing water replenishment and ventilation / dehumidification operations based on changes in state include: During the high-temperature fumigation period, the soil electrical conductivity, soil volumetric water content, and soil temperature were periodically measured. When the soil volumetric moisture content deviates from the preset moisture range, water replenishment operations are performed. Ventilation and dehumidification operations are performed when the soil temperature or soil electrical conductivity deviates from the preset range. The system alternates between water replenishment and ventilation / dehumidification operations.

[0060] Specifically, after the sealed fumigation environment is formed in S6, the high-temperature fumigation treatment stage begins. During this stage, the greenhouse structure remains unchanged, and only the moisture and gas exchange inside the greenhouse is controlled. Soil condition data is collected based on the fixed monitoring points set up in S1. The soil electrical conductivity, soil volumetric water content, and soil temperature of the topsoil are continuously acquired according to a predetermined collection cycle, and the collection results are recorded as time series data.

[0061] At any acquisition time t, the acquired soil state parameters are represented as a state vector: ; in, This indicates the soil electrical conductivity state at time t; This indicates the soil volumetric water content at time t. This indicates the soil temperature state at time t.

[0062] The state vector serves as the basis for determining water replenishment and ventilation / dehumidification operations.

[0063] During the high-temperature fumigation period, when the soil volumetric moisture content was monitored... When the moisture level exceeds the preset range, a water replenishment operation is performed. This operation replenishes moisture to the agricultural facility, bringing the improved topsoil back within the preset moisture range. After water replenishment, soil condition data is collected to confirm the impact of the water replenishment operation on soil volumetric moisture content.

[0064] When monitoring soil temperature status or soil electrical conductivity status When the temperature exceeds the preset range, ventilation and dehumidification are performed. This involves opening the greenhouse vents to exchange air between the greenhouse and the outside environment, thus altering the temperature and humidity conditions inside the greenhouse. After ventilation and dehumidification are completed, the vents are closed and the greenhouse is restored to a sealed state, followed by continued soil condition monitoring. During water replenishment and ventilation / dehumidification, these two operations are not performed simultaneously; instead, they are alternately adjusted based on changes in soil condition parameters. Ventilation and dehumidification are not performed while water replenishment is in progress or has just been completed; conversely, water replenishment is not performed while ventilation and dehumidification are in progress or have just been completed. This method ensures that moisture regulation and gas exchange during high-temperature greenhouse treatment follow the sequence of soil condition changes.

[0065] To characterize the changes in soil state during high-temperature fumigation, adjacent data collection times can be defined. and The state change between them is: ; in, Indicates the time interval Changes in soil electrical conductivity, soil volumetric water content, and soil temperature.

[0066] By continuously collecting soil state parameters during the high-temperature fumigation treatment, and alternating water replenishment and ventilation and dehumidification operations according to the changing sequence of state parameters, the moisture conditions and internal environment of the greenhouse during the fumigation treatment process are kept in correspondence with the actual state of the improved topsoil, thereby ensuring that the high-temperature fumigation treatment is carried out continuously according to a unified state judgment logic throughout the entire implementation process.

[0067] Furthermore, in step S8, the greenhouse is ventilated and dehumidified, followed by land preparation and ridging of the agricultural land, and the rotation crop is planted on the ridged cultivation bed to enter the next rotation cycle. Remove the mulch film after ventilation and dehumidification are complete; Leveling and ridging of the topsoil; Plant the crops on the formed ridges according to the order of crop rotation.

[0068] In step S8, after the rotation crop completes one growth cycle, its above-ground parts are retained in the facility farmland and used as the treatment object for the in-situ straw crushing and returning step in the next round S3. This ensures that the rotation crop configuration step, the in-situ straw crushing and returning step, the organic material and microbial agent application step, the rotary tillage and mixing step, the irrigation and humidity regulation and high-temperature fumigation step, and the state trigger control step are continuously executed in a cycle according to the rotation cycle. Specifically, after S7 is completed, the high-temperature fumigation treatment ends. First, the greenhouse vents are opened for ventilation and dehumidification, allowing the air inside the greenhouse to exchange with the outside environment and reducing the humidity and temperature inside the greenhouse. After ventilation and dehumidification are completed, the mulch covering the improved topsoil surface is removed, allowing the topsoil surface to be fully exposed, and the regular land preparation work can begin.

[0069] After removing the plastic film, the topsoil is leveled to eliminate surface unevenness caused by the high-temperature fumigation and ventilation process. Ridging is then carried out, shaping the topsoil along predetermined ridges to form regularly distributed cultivation beds. These beds remain in place throughout a crop rotation cycle, serving as the basic structure for planting and growing the rotation crops. After ridging, the rotation crops are planted on the formed ridges according to the crop rotation arrangement determined in step S2. During planting, the planting location of the rotation crops is confined to the cultivation beds, ensuring that the root growth area corresponds to the improved topsoil. After planting, the rotation crops enter the growth management stage.

[0070] After the rotation crop completes a growth cycle and is harvested, its above-ground parts are not removed but left in the facility farmland as the material to be processed in the in-situ straw crushing and returning step of the next S3 cycle. This process ensures that the crop residues from the previous rotation cycle directly enter the in-situ straw crushing and returning process of the next rotation cycle, thus achieving a continuous temporal sequence between the rotation crop configuration step, the in-situ straw crushing and returning step, the organic material and microbial agent application step, the rotary tillage and mixing step, the irrigation and humidity regulation and high-temperature fumigation step, and the state triggering control step.

[0071] To represent the continuous execution relationship of the crop rotation cycle, let the crop rotation cycle be numbered k. After the k-th crop rotation cycle ends, the (k+1)-th crop rotation cycle begins. Then the crop rotation process can be represented as: ; in, This represents the complete processing flow consisting of steps S2 to S8 executed sequentially within the k-th cycle.

[0072] By completing ventilation and dehumidification, land preparation and ridging, crop rotation planting and crop residue retention in S8, the improved tillage layer after high-temperature fumigation treatment can directly transition to the cultivation stage of the next crop rotation cycle. After the crop growth cycle ends, the straw in-situ crushing and returning to the field step is seamlessly connected, thereby ensuring that the method of the present invention can be continuously and repeatedly executed in facility agricultural land according to the established crop rotation cycle.

[0073] Example 2: This example uses facility-grown agricultural land as the implementation object. Under the condition of rotating facility vegetable crops and grain crops, a method of improving moderately salinized soil by rotating crop straw and returning it to the field is implemented. The method and steps used in this example are the same as those in the aforementioned implementation method, the difference being the configuration of the rotation crop types.

[0074] In this embodiment, multiple fixed monitoring points are first set up within the topsoil of the facility farmland. These monitoring points are positioned along the crop planting rows and ridges, and their locations remain unchanged within the same crop rotation cycle. The soil electrical conductivity, soil volumetric water content, and soil temperature are collected from these monitoring points, and the collected data are then aggregated and processed. When the aggregated soil electrical conductivity meets the criteria for moderately saline soil, the facility farmland is determined to be moderately saline soil and proceeds to the subsequent remediation process.

[0075] After determining that the farmland for greenhouse agriculture was moderately saline-alkali soil, a rotation system of greenhouse vegetable crops and grain crops was implemented to form a rotation crop sequence. Within one rotation cycle, greenhouse vegetable crops were planted on the same ridge; in the next rotation cycle, grain crops were planted on the same ridge, ensuring that greenhouse vegetable crops and grain crops alternated in time. The configuration of the rotation crop sequence corresponded to the production season of the farmland for greenhouse agriculture and served as the crop source for subsequent straw return treatment.

[0076] After harvesting greenhouse vegetables or grain crops, the above-ground crop residues are left within the greenhouse farmland. Subsequently, the crop residues are shredded in situ along the planting ridges using shredding equipment, and the shredded straw is evenly spread along the ridges to cover the entire surface of the cultivated layer, thus forming a straw layer.

[0077] After the straw layer is formed, well-rotted organic materials are evenly spread on the surface of the straw layer. At the same time or after the well-rotted organic materials are spread, microbial agents are applied to the straw layer by spreading or rinsing with water, so that the straw layer, organic materials and microbial agents form a composite material layer that is spatially interspersed.

[0078] After the composite material layer is constructed, rotary tillage machinery is used to perform rotary tillage operations along the ridge direction on the facility farmland, turning the straw layer, decomposed organic materials, and microbial agents into the tillage layer. Subsequently, through at least one cross-rotation operation in a direction different from the ridge direction, the above materials form a continuously distributed mixed structure within the tillage layer, thereby forming an improved tillage layer.

[0079] After the improved topsoil is formed, the farmland is irrigated to keep the topsoil moist. After irrigation, a plastic film is laid on the surface of the improved topsoil, and the greenhouse ventilation openings are closed to put the farmland into a sealed, fumigated state, thus subjecting the farmland to high-temperature fumigation treatment.

[0080] During the high-temperature fumigation treatment, the soil electrical conductivity, soil volumetric moisture content, and soil temperature in the topsoil layer were periodically collected. Watering and ventilation / dehumidification operations were performed based on these changes. Watering was performed when the soil volumetric moisture content deviated from the preset range; ventilation / dehumidification was performed when the soil temperature or soil electrical conductivity deviated from the preset range. Watering and ventilation / dehumidification operations were alternated during the high-temperature fumigation treatment.

[0081] After the high-temperature fumigation treatment, the greenhouse vents are opened for ventilation and dehumidification, and the mulch film is removed. Subsequently, the farmland is prepared and leveled, and raised beds are created along the predetermined ridge direction to form regularly distributed cultivation beds. The next rotation crop is planted on these beds according to the rotation crop configuration. After the rotation crop completes one growth cycle and is harvested, its above-ground residue remains on the farmland as the material for the in-situ straw crushing and returning step in the next rotation cycle. Through these steps, the in-situ straw crushing and returning, high-temperature fumigation treatment, and state-triggered control steps under the rotation conditions of greenhouse vegetable and grain crops are continuously and cyclically executed within the farmland according to the rotation cycle.

[0082] Example 3: In this example, multiple fixed monitoring points are set up along the crop planting row direction and ridge direction within the topsoil of the facility agricultural land. At each monitoring point, the soil electrical conductivity, soil volumetric water content, and soil temperature are collected according to a unified collection process. The collection results are recorded with time as the index to reflect the state changes of the topsoil at different operation stages. The collection parameters of each monitoring point are kept consistent to avoid introducing bias. In order to uniformly represent the data of multiple monitoring points, the data of each monitoring point collected at the same time are summarized and processed to form a soil state dataset representing the overall topsoil state of the facility agricultural land.

[0083] Based on the above soil condition dataset: Figure 2 The dynamic changes in soil volumetric water content at 10 cm and 30 cm depth throughout the entire growth period of tomato soil are derived from the summarized data on the changes in soil volumetric water content over time. Figure 3 The graphs showing the dynamic changes in soil electrical conductivity at depths of 10 cm and 30 cm throughout the entire tomato growth period are derived from compiled data on the changes in soil electrical conductivity over time. Figure 4 The soil desalination rate and salt return rate shown for different measures are obtained by comparing and statistically analyzing the changes in soil salinity / electrical conductivity in the topsoil under different treatment conditions during the treatment period. Figure 5 The soil salinity influencing factors at 10 cm and 30 cm depths shown are obtained by analyzing the correspondence between soil salinity changes at different depths of the topsoil and the control processes such as water and ventilation during the treatment.

[0084] To facilitate understanding of the specific meaning of the different processing methods in the attached figures, the following is a summary: Figure 6 The experimental measures represented by each treatment number are explained below: Figure 6 The processing methods are as follows: CF: Conventional fertilizer application treatment, which is the application of chemical fertilizers in the process of planting in facility agriculture land according to conventional production methods, without the implementation of straw return to the field and soil improvement and control measures, as a control treatment; OM: Organic material application treatment, which is a treatment method that involves applying well-rotted organic materials into the soil on the basis of conventional fertilization; RF: Crop rotation straw return treatment, which means implementing crop rotation and returning crop straw to the field in situ without subsequent microbial regulation treatment; RF+BS: Crop rotation straw return to the field combined with the application of microbial agent BS, where BS is a form of microbial agent used to promote straw decomposition and soil microecological regulation; RF+SL: Crop rotation straw return combined with the application of soil conditioner SL, where SL is a form of soil conditioner. RF+S+BS: Integrated regulation and treatment, which is a treatment method that combines the in-situ crushing and returning of crop rotation straw to the field with the simultaneous application of organic materials and microbial agents, and the implementation of rotary tillage, high-temperature fumigation and state regulation steps. This treatment method corresponds to the crop rotation straw return method for improving moderately salinized soil in facility agricultural land described in the embodiments of the present invention.

[0085] Among them, the RF+S+BS treatment is the treatment method implemented using the technical solution of the present invention, and the other treatments are used as comparative treatments to illustrate the effects of the method of the present invention on crop nutrient absorption and soil improvement.

[0086] Figure 6 The graph showing the effects of different control measures on nutrient absorption in tomatoes is derived from the measurement / statistical results of nutrient absorption during the growth of greenhouse tomatoes under different control measures. It is also compared with the soil electrical conductivity, soil volumetric water content and soil temperature data collected continuously during the high-temperature fumigation treatment.

[0087] Please refer to Figures 2-6 This embodiment uses greenhouse tomato cultivation land as the implementation object, and implements a crop rotation and straw return method to improve moderately saline soil under multi-regional greenhouse tomato production conditions. This embodiment is used to illustrate the specific application of the method of the present invention in continuous cultivation of greenhouse vegetable crops and multi-site conditions.

[0088] In this embodiment, fixed monitoring points are set up within the facility farmland, located at different positions in the topsoil and covering the tomato planting area. Soil electrical conductivity, soil volumetric moisture content, and soil temperature are collected at different depths within the topsoil through these monitoring points, and the collected data are summarized and processed. When the summarized soil electrical conductivity meets the criteria for moderately saline soil, the facility farmland is determined to be moderately saline soil, and the crop rotation and straw return improvement process is initiated. In the crop rotation configuration step, combined with the cultivation system of facility tomatoes, facility tomatoes are included as a facility vegetable crop type in the crop rotation sequence, forming a crop rotation sequence with non-similar crops. The rotation crops are planted sequentially on the same ridge according to the cropping order, allowing facility tomatoes to alternate with other crop types during the rotation cycle.

[0089] After greenhouse tomatoes complete one growth cycle and are harvested, the above-ground plant remains are left within the greenhouse farmland. Subsequently, the tomato plant remains are pulverized in situ along the planting ridges, ensuring the pulverized tomato straw is evenly spread on the surface of the tillage layer, forming a straw layer. Following the formation of the straw layer, well-rotted organic matter is applied to the surface, along with a microbial agent, creating a composite layer of tomato straw, organic matter, and microbial agents that is interleaved on the tillage surface. This composite layer is then incorporated into the original soil through rotary tillage. In this step, rotary tillage machinery is used to till the greenhouse farmland along the ridges, incorporating the tomato straw, organic matter, and microbial agents into the tillage layer. Cross-tillage further enhances the quality of the materials, creating a continuously distributed improved tillage layer.

[0090] After the improved topsoil layer is formed, the farmland is irrigated to keep it moist. Following irrigation, mulch is laid to cover the soil surface, and then the greenhouse ventilation openings are closed, creating a sealed, fumigated environment for high-temperature fumigation of the improved topsoil. During this process, soil electrical conductivity, soil volumetric moisture content, and soil temperature are continuously monitored. Watering and ventilation / dehumidification operations are performed based on these changes. Watering is initiated when the soil volumetric moisture content deviates from the preset range; ventilation / dehumidification is performed when the soil temperature or electrical conductivity deviates from the preset range, alternating between sealed and ventilated conditions during the fumigation process.

[0091] After the high-temperature fumigation treatment, the greenhouse is ventilated and dehumidified, and the mulch film is removed. The land is then prepared and leveled, and ridges are formed along the predetermined ridge direction to create cultivation beds for planting greenhouse tomatoes. The next rotation crop is planted on these cultivation beds, marking the start of the next crop rotation cycle. After the next crop rotation cycle ends, the above-ground residues of the planted crops remain on the greenhouse land and are used for subsequent in-situ straw pulverization and return to the field. This ensures that the steps of crop rotation, in-situ straw pulverization and return to the field, application of organic materials and microbial agents, rotary tillage and layering, irrigation and humidity control, high-temperature fumigation treatment, and state trigger control are continuously and cyclically executed within the greenhouse land according to the crop rotation cycle.

[0092] Figure 2 This diagram illustrates the changes in soil volumetric moisture content at different depths within the tillage layer over the entire growth period of greenhouse tomatoes. Specifically, it reflects the changes in soil volumetric moisture content at locations near the upper tillage layer and in the lower middle tillage layer. Figure 2 It can be seen that under the crop rotation straw return to the field, high temperature greenhouse and state trigger control process adopted in this embodiment, the soil volume moisture content at different depths of the tillage layer remains continuously changing during the tomato growth period, and is adjusted accordingly with the execution of water replenishment and ventilation dehumidification operations. This change process corresponds to the control logic of performing water replenishment operation based on soil volume moisture content in S7.

[0093] Reference Figure 3 , Figure 3 This study shows the changes in soil electrical conductivity at different depths in the tillage layer over time throughout the entire growth period of greenhouse tomatoes. Figure 3 The electrical conductivity status reflected in the data is used to characterize the changing trend of soil salinity distribution in the topsoil during the tomato growth period. In this embodiment, by continuously collecting soil electrical conductivity status during the high-temperature fumigation treatment and performing ventilation and dehumidification operations when it deviates from the preset state range, the soil electrical conductivity status at different depths of the topsoil is adjusted over time. This change process corresponds to the implementation method of ventilation and dehumidification regulation based on soil electrical conductivity status in step S7.

[0094] Reference Figure 4 , Figure 4 This diagram illustrates a comparison of changes in topsoil salinity under different treatment conditions. Figure 4 The different treatment measures shown correspond to whether or not crop rotation straw return to the field, application of organic materials and microbial agents, and high-temperature fumigation treatment are performed. The treatment process used in this embodiment corresponds to... Figure 4 It includes measures such as in-situ straw crushing and returning to the field, rotary tillage and mixing, and high-temperature fumigation treatment, which are used to illustrate the changes in the soil salinity of the topsoil during the treatment cycle under this process.

[0095] Reference Figure 5 , Figure 5 The diagram illustrates the influencing factors of soil salinity changes at different depths of the topsoil. Figure 5 This study reflects the impact of different depths of the topsoil on crop rotation with straw return, high-temperature fumigation, and other control processes. By creating an improved topsoil layer through rotary tillage and mixing, and by alternately controlling moisture and ventilation during the high-temperature fumigation stage, different depths of the topsoil are subjected to uniform treatment conditions within the same treatment system. This treatment method is similar to... Figure 5 The characteristics of the stratification of the tillage layer are shown.

[0096] Reference Figure 6 , Figure 6 This diagram illustrates the changes in nutrient absorption status of greenhouse tomatoes during their growth process under different control measures. Figure 6 The different control measures shown correspond to whether or not a state-triggered control step is executed. By continuously collecting soil electrical conductivity, soil volumetric water content, and soil temperature data during high-temperature fumigation, and performing water replenishment and ventilation / dehumidification operations based on these data, the greenhouse tomatoes are kept in an environmental condition corresponding to the improved topsoil state during their growth process. This process is related to... Figure 6 The control measures shown correspond to each other, and can be combined with Figures 2 to 6 The soil volumetric water content, electrical conductivity, and changes under different control measures are shown in this embodiment. This embodiment further illustrates the specific implementation process of the method of the present invention under the conditions of greenhouse tomato rotation and the correspondence between soil state control at different growth stages.

[0097] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for improving moderately salinized soil in facility-based agricultural land through crop rotation and straw return, characterized in that, Includes the following steps: S1. Set up monitoring points in the cultivated layer of facility agricultural land to collect soil electrical conductivity, soil volumetric water content and soil temperature data, and determine the facility agricultural land as moderately saline soil based on the collected soil electrical conductivity data. S2. On facility agricultural land that is determined to be moderately saline soil, implement crop rotation between deep-rooted crops and shallow-rooted crops, or implement crop rotation between facility vegetable crops and grain crops to form a crop rotation sequence. S3. The above-ground residues of the previous crop rotation are crushed in situ within the facility farmland, and the crushed straw is evenly spread on the surface of the cultivated layer to form a straw layer. S4. Apply decomposed organic material onto the straw layer and simultaneously apply microbial agents to form a composite material layer of straw layer, organic material and microbial agents. S5. Rotary tillage is performed on the composite material layer and the original soil to mix straw, organic materials and microbial agents into the tillage layer to form an improved tillage layer. S6. Irrigate the improved tillage layer, then cover it with mulch and seal the greenhouse to carry out high-temperature fumigation treatment on the facility agricultural land. S7. During the high-temperature fumigation treatment, continuously collect soil electrical conductivity, soil volumetric water content and soil temperature, and perform water replenishment and ventilation dehumidification operations according to the changes in the states. S8. After the high-temperature fumigation treatment is completed, the greenhouse is ventilated and dehumidified. Then, the land for facility agriculture is prepared and ridged, and rotation crops are planted on the ridged cultivation beds to enter the next rotation cycle.

2. The method for improving moderately salinized soil in facility-farmed agricultural land by crop rotation and straw return as described in claim 1, characterized in that, In step S1, the step of determining that the facility agricultural land is moderately saline soil based on the collected soil electrical conductivity status includes: Multiple fixed monitoring points were set up along the crop planting rows and ridges within the facility agricultural land; At each monitoring point, the soil electrical conductivity, soil volumetric water content and soil temperature were collected. The collected data from each monitoring point are summarized and processed to form a soil condition dataset for S6 and S7 control.

3. The method for improving moderately salinized soil in facility-farmed agricultural land by crop rotation and straw return as described in claim 1, characterized in that, In step S2, the step of configuring deep-rooted crops and shallow-rooted crops for rotation, or configuring greenhouse vegetable crops and grain crops for rotation, to form a crop rotation sequence on facility agricultural land determined to be moderately saline soil, includes: The order of cropping deep-rooted crops and shallow-rooted crops should be determined according to the cultivation system of facility agriculture land. Within a crop rotation cycle, deep-rooted crops and shallow-rooted crops are planted sequentially on the same ridge. In the next crop rotation cycle, the crop types from the previous cycle will be swapped with those from the current cycle.

4. The method for improving moderately salinized soil in facility-farmed agricultural land by crop rotation and straw return as described in claim 1, characterized in that, In step S3, the step of evenly spreading the crushed straw on the surface of the tillage layer to form a straw layer includes: Leave the crop stalks on the ground after harvest; The stems are shredded in situ using a shredding device; Spread the chopped straw evenly along the direction of the planting ridges so that the straw covers the entire surface of the cultivated layer.

5. The method for improving moderately salinized soil in facility-farmed agricultural land by crop rotation and straw return as described in claim 1, characterized in that, In step S4, the step of simultaneously applying the microbial agent to form a composite material layer from the straw layer, organic material, and microbial agent includes: Evenly spread well-rotted organic materials on the surface of the straw layer; Microbial agents are applied to the straw layer by spreading or flushing with water while or after spreading the decomposed organic materials. This allows the microbial agents to be spatially interspersed with straw and decomposed organic materials.

6. The method for improving moderately salinized soil in facility-farmed agricultural land by crop rotation and straw return as described in claim 1, characterized in that, In step S5, the composite material layer and the original soil are subjected to rotary tillage to mix straw, organic materials, and microbial agents into the tillage layer, forming an improved tillage layer. This step includes: Rotary tillage machinery is used to perform rotary tillage operations along the ridge direction on facility farmland; The straw layer, decomposed organic material, and microbial agents are all turned into the soil layer. Multiple cross-rotation tillage processes create a continuous mixed layer of the above materials within the tillage layer.

7. The method for improving moderately salinized soil in facility-farmed agricultural land by crop rotation and straw return as described in claim 1, characterized in that, In step S6, the steps of irrigating the improved tillage layer, then covering it with mulch and sealing the greenhouse to implement high-temperature fumigation treatment for facility agriculture include: After rotary tillage and mixing are completed, the facility farmland is irrigated to keep the entire topsoil moist. After irrigation, lay a plastic film to cover the soil surface; Close the vents in the greenhouse to create a sealed, stuffy environment inside.

8. The method for improving moderately salinized soil in facility-farmed agricultural land by crop rotation and straw return as described in claim 1, characterized in that, In step S7, the steps of performing water replenishment and ventilation / dehumidification operations based on the changes in the state include: During the high-temperature fumigation period, the soil electrical conductivity, soil volumetric water content, and soil temperature were periodically measured. When the soil volumetric moisture content deviates from the preset moisture range, water replenishment operations are performed. Ventilation and dehumidification operations are performed when the soil temperature or soil electrical conductivity deviates from the preset range. The system alternates between water replenishment and ventilation / dehumidification operations.

9. The method for improving moderately salinized soil in facility-farmed agricultural land by crop rotation and straw return as described in claim 1, characterized in that, In step S8, the steps of ventilating and dehumidifying the greenhouse, then preparing and ridging the land for agricultural use, and planting rotation crops on the ridged cultivation beds to enter the next crop rotation cycle include: Remove the mulch film after ventilation and dehumidification are complete; Leveling and ridging of the topsoil; Plant the crops on the formed ridges according to the order of crop rotation.

10. The method for improving moderately salinized soil in facility-farmed agricultural land by crop rotation and straw return as described in claim 1, characterized in that, In step S8, after the crop rotation crop completes one growth cycle, its above-ground parts are retained in the facility agricultural land and used as the processing object for the straw in-situ crushing and returning to the field step in the next round S3. This ensures that the crop rotation crop configuration step, the straw in-situ crushing and returning to the field step, the organic material and microbial agent application step, the rotary tillage and mixing step, the irrigation and humidity regulation and high-temperature fumigation step, and the state trigger control step are continuously and cyclically executed according to the crop rotation cycle.

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