A method for building soil configuration of shallow groundwater uniform sand heavy saline-alkali land

Abstract

This invention relates to the field of soil engineering technology for saline-alkali land, and discloses a method for creating soil configuration in severely saline-alkali land with uniform sandy soil and shallow groundwater. The method includes: screening plots and performing preliminary zoning; selecting zoning with uniform sandy soil characteristics based on soil profile parameters; sequentially dividing the land into functional zones and simultaneously classifying crop root types; dividing the soil profile of each functional zone into a surface salt-controlling and draining layer, a root zone suitable layer, and a lower salt-blocking and regulating layer; optimizing and regulating the salt-blocking materials of the lower salt-blocking and regulating layer, the improvement materials of the root zone suitable layer, and the parameters of the surface salt-controlling and draining layer, and then implementing the soil configuration for each functional zone; obtaining the parameters of each functional zone after the soil configuration implementation, controlling and adjusting them, and simultaneously setting up sampling points to calculate the soil configuration and salt control indicators of each functional zone to evaluate the soil configuration compliance and salt control effect; this invention significantly improves the suitable soil configuration environment for crop planting.

Description

Technical Field

[0001] This invention relates to the field of soil engineering technology for saline-alkali land, specifically to a method for constructing soil structure in shallowly buried groundwater sandy, heavily saline-alkali land. Background Technology

[0002] In areas with high evaporation, low rainfall, and shallow groundwater depth, severely saline-alkali sandy soils commonly suffer from problems such as continuous upward movement of groundwater salinity, repeated surface salt return, and poor root zone suitability. Unlike typical saline-alkali soils, which are mainly characterized by high surface salinity, these types of lands typically exhibit the following characteristics: shallow groundwater depth, with evaporation significantly exceeding natural rainfall leaching; soil composition dominated by sand particles, with minimal differences in texture between soil layers; low organic matter content in the topsoil, weak water and fertilizer retention capacity, and poor natural structural stability. Under these combined conditions, groundwater and the salts it carries easily migrate upwards along the continuous pores and capillary channels of the soil profile, accumulating in the root zone and surface layer. This results in the topsoil being in a state of high salinity or prone to salt return for extended periods, significantly restricting crop emergence, growth, and yield stability.

[0003] Existing saline-alkali land improvement technologies mainly include mulching, drip irrigation, application of organic fertilizer or gypsum to the topsoil, straw return to the field, and salt leaching through irrigation and drainage. While these measures can reduce surface evaporation, improve topsoil fertility, regulate local salt distribution, or promote salt leaching under certain conditions, they primarily affect the surface or topsoil, lacking a systematic approach to control the continuous upward movement of salts driven by groundwater at the profile scale. Furthermore, existing technologies often rely on single measures or simple superposition, lacking a systematic approach that identifies, configures, and links parameters based on differences in dominant limiting factors across different land parcels. This makes it difficult to achieve the three-dimensional configuration goals of deep salt inhibition, mid-layer soil improvement and fertilization, and surface salt control and drainage.

[0004] Furthermore, in sandy, severely saline-alkali lands, due to the high sand content and low content of fine particles and cementitious materials, the natural soil lacks stable barrier interfaces, resulting in strong continuity and sensitivity in water and salt migration processes. For such plots, simply adopting uniform tillage depth, uniform material application rates, or uniform surface agronomic measures often fails to adapt to the differences in groundwater recharge risk, root zone structural vulnerability, and salt return intensity among different zones, leading to unstable improvement effects and poor engineering repeatability. Summary of the Invention

[0005] To address the aforementioned shortcomings in existing technologies, this invention provides a method for constructing soil structure in shallowly buried groundwater, uniformly sandy, and severely saline-alkali land. This method aims to solve the problems of continuous upward flow of groundwater salts, frequent surface salt return, and poor root zone suitability in severely saline-alkali land characterized by high evaporation, low rainfall, shallowly buried groundwater, uniform sandy texture, and low organic matter.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A method for constructing soil structure in shallowly buried, sandy, severely saline-alkali land includes the following steps: The plots were screened and initially divided. Based on the soil profile parameters, the plots with uniform sandy characteristics were screened. Functional zoning was carried out in sequence, and the crop root system type was classified at the same time. The soil profile of each functional zone is divided into a surface salt-controlling and salt-discharging layer, a root zone suitable layer, and a lower salt-blocking and regulating layer. After optimizing and regulating the parameters of the salt-blocking material in the lower salt-blocking control layer, the improved material in the root zone adaptation layer, and the surface salt-controlling and salt-draining layer, the soil configuration of each functional zone is implemented. After the implementation of the soil configuration, the parameters of each functional zone are obtained, controlled and adjusted, and sampling points are set up to calculate the soil configuration and salinity control indexes of each functional zone in order to evaluate the soil configuration compliance and salinity control effect.

[0007] Further, the process involves screening plots and making preliminary zoning. Based on soil profile parameters, zoning with homogeneous sandy characteristics is selected, and functional zoning is carried out sequentially. Simultaneously, the process of classifying crop root types is also completed: Based on groundwater depth, surface and subsurface salinity, and soil profile mechanical composition, land parcels are screened to generate initially qualified parcels. Several survey points were set up within the initially qualified plots to obtain the groundwater depth, salinity index and organic matter content parameters of each survey point, and preliminary zoning was carried out based on the parameter characteristics. Representative profile points were selected within each preliminary zone, and the soil profile parameters of each representative profile point were tested. Preliminary zones with homogeneous sandy characteristics were screened to obtain several improvement operation zones. Based on soil profile parameters, each improvement operation zone is functionally divided into zones dominated by salt replenishment risk, zones dominated by root zone vulnerability, and zones with limited synergy. Based on the depth of the lower boundary of the main root activity layer, crops are classified into shallow-rooted crops, medium-rooted crops, and deep-rooted crops.

[0008] Furthermore, the process of selecting preliminary zones with homogeneous sandy characteristics is as follows: Let the first The first preliminary partitioning in the The mass fraction of sand particles in each soil profile section is: The corresponding layer thickness is The weighted average sand content of this preliminary partition is... for:

[0009] in, Initial partition numbering; Numbering of soil profile sections; For the first The first preliminary partition The thickness of each soil layer section in the profile; For the first Weighted average sand content of each preliminary zone; Calculate the difference between the maximum and minimum mass fraction of sand particles in this preliminary partition:

[0010] in, For the first The difference between the maximum and minimum mass fraction of sand particles in each preliminary zone; For the first The maximum mass fraction of sand particles in each preliminary zone; For the first The minimum mass fraction of sand particles in each preliminary zone; Determine the weighted average sand content Is it greater than or equal to a preset sand content threshold, and what is the difference? If the initial zone is less than or equal to the preset quality difference, then the initial zone has the characteristics of uniform sand and is defined as an improvement zone; otherwise, the initial zone does not have the characteristics of uniform sand and is not processed.

[0011] Furthermore, the process of dividing the soil profile of each functional zone into a surface salt-controlling and salt-draining layer, a root zone suitable layer, and a lower salt-prevention and regulation layer is as follows: Determine the ridge height, ridge width, ridge width, and trench width for each functional zone, construct trapezoidal ridges and trenches, obtain the location of the surface salt-controlling and salt-discharging layer in the soil profile, and calculate the proportion of low-level buffer salt-collecting zones for each functional zone. Based on the functional zones as the lower boundary depth of the main root activity layer and the root buffer margin, the lower boundary depth of the suitable root zone is calculated, and the upper boundary depth of the suitable root zone is set as the reference surface. The thickness of the suitable root zone is calculated to obtain the position of the suitable root zone in the soil profile. The reference surface is the original ground surface after leveling before ridging. Set the retention distance between the root zone suitable layer and the lower salt-controlling layer for each functional zone, calculate the upper limit depth of the lower salt-controlling layer, set the thickness of the lower salt-controlling layer, calculate the upper limit depth of the lower salt-controlling layer, and obtain the position of the lower salt-controlling layer in the soil profile.

[0012] Furthermore, the process of optimizing and regulating the parameters of the salt-blocking material in the lower salt-blocking control layer, the improved material in the root zone adaptation layer, and the surface salt-controlling and salt-draining layer is as follows: The salt barrier material of the lower salt barrier control layer is preset, and the amount of salt barrier material to be laid is calculated, i.e.:

[0013] in, Number the functional partitions; It is a salt-barrier material type; Functional partition Salt barrier material of the lower salt barrier control layer The amount of material laid; Functional partition The thickness of the lower salt barrier layer; Salt barrier material The equivalent packing density; Functional partition Salt barrier material of the lower salt barrier control layer Coverage rate; Functional partition Salt barrier material of the lower salt barrier control layer Moisture content; Calculate the soil mass of the root zone suitable layer based on the soil unit weight.

[0014] in, Functional partition Soil quality in the root zone suitable layer; Functional partition The thickness of the root zone adaptation layer; Functional partition The soil bulk density of the root zone suitable layer; Based on the soil quality of the root zone's suitable growing layer, and combined with the target dry basis mass fraction of organic fertilizer and calcium-containing amendment, the application rates of organic fertilizer and calcium-containing amendment in the root zone's suitable growing layer are calculated, i.e.:

[0015]

[0016] in, , Functional partitions The amount of organic fertilizer and calcium-containing amendments applied to the root zone's suitable growth layer; , Functional partitions The target dry basis mass fraction of organic fertilizer materials and calcium-containing amendment materials; , Functional partitions The moisture content of organic fertilizer materials and calcium-containing amendment materials; Obtain the film coverage rate of the surface salt control and salt discharge layer and the proportion of the low-level buffer salt collection area; Ultimately, by regulating the coverage rate of salt-blocking materials in the lower salt-blocking control layer of different types of functional zones, the target dry basis mixing mass fraction of organic fertilizer materials and calcium-containing improvement materials in the root zone suitable layer, the film coverage rate of the surface salt-controlling and salt-draining layer, and the proportion of the low-level buffer salt collection zone, the optimal configuration of parameters for each functional zone is achieved.

[0017] Furthermore, the process of implementing the soil configuration for each functional zone is as follows: For each functional zone, crops are placed, ditches or trenches are dug, salt-blocking materials are laid in the lower salt-controlling layer, soil is backfilled, organic fertilizer materials and calcium-containing amendment materials are placed in the root zone suitable layer and mixed evenly, a surface salt-controlling and salt-draining layer is constructed and covered with surface salt-controlling and salt-draining layer covering material, and finally a local water-saving irrigation system is deployed to realize the soil structure creation of severely saline-alkali land.

[0018] Furthermore, the process of obtaining parameters for each functional zone after the implementation of the soil configuration, controlling and adjusting them, setting up sampling points, and calculating the soil configuration and salinity control indices for each functional zone to evaluate the effectiveness of soil configuration compliance and salinity control is as follows: The parameters of each functional zone were extracted and checked, including the thickness of the root zone suitable layer, the upper and lower boundary depths and thicknesses of the lower salt-controlling layer, the coverage of salt-controlling materials, the ridge width, the furrow width, the ridge thickness of the surface salt-controlling and salt-draining layer, the mulch coverage, and the layout of the local water-saving irrigation system. During the early stages of crop growth and the period of salt return sensitivity, the salt content of the surface monitoring layer and subsurface monitoring layer of each functional zone is tracked and investigated in real time. If surface salt return is enhanced, the coverage of salt-blocking materials, the frequency of local water supply, or the width of the trench is adjusted. Sampling points were set up in each functional zone. Based on the salinity index of the surface monitoring layer and subsurface monitoring layer after and before the implementation of the soil configuration, the salinity reduction rate of the surface monitoring layer and subsurface monitoring layer was calculated respectively. Determine whether the salt reduction rate of both the surface monitoring layer and the subsurface monitoring layer is not lower than the preset threshold. If so, the sampling point is a qualified point; otherwise, the sampling point is an unqualified point. Calculate the overall pass rate of each functional zone and determine whether the overall pass rate is greater than or equal to the preset threshold. If it is, the functional zone passes the acceptance test; otherwise, the functional zone fails the acceptance test.

[0019] The present invention has the following beneficial effects: This invention proposes a method for creating soil structure in shallowly buried, sandy, and severely saline-alkali land. By dividing the land into zones and constructing a three-layer synergistic soil structure consisting of a surface salt-controlling and draining layer, a root zone suitable layer, and a lower salt-blocking and regulating layer, this method achieves comprehensive improvement from surface to profile, from unified to zoned, from single-item superposition to three-layer synergy, from experience-based application to parameter linkage, and from experience-based construction to engineering closed-loop. It can also quantitatively control water and salt migration in the profile, configure improvement schemes differently for each zone, and form a closed-loop engineering acceptance system. This effectively reduces groundwater recharge and return, improves the root zone growth environment, and significantly enhances the pertinence, stability, and sustainability of the improvement effect, thereby creating a suitable soil environment for crop growth in the long term. Attached Figure Description

[0020] Figure 1 This is a schematic flowchart of a method for constructing soil structure in shallowly buried groundwater sandy and severely saline-alkali land proposed in this invention. Figure 2 This is a schematic diagram of the soil mechanical composition in a severely saline-alkali land area, as shown in the example. Figure 3 This is a schematic diagram comparing the pH and salinity of the method proposed in this invention with a control in the embodiments; Figure 4 This is a schematic diagram comparing the corn growth indicators of the method proposed in this invention with those of the control in the embodiments. Figure 5 This is a schematic diagram comparing the corn yield of the method proposed in this invention with that of the control in the embodiments. Detailed Implementation

[0021] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0022] The specific embodiments of this invention are as follows: like Figure 1 As shown, a method for constructing soil structure in shallowly buried, sandy, severely saline-alkali land includes the following steps: Step 1: Select plots and perform preliminary zoning. Based on soil profile parameters, select zoning with uniform sandy characteristics, and then divide them into functional zoning zones in sequence, while simultaneously completing the classification of crop root system types.

[0023] This step is to screen the applicable objects of the present invention and form the basic unit for subsequent configuration and construction; in order to take into account both practical operability and configuration design needs, a technical route of initial screening of applicable objects and two-level investigation is adopted; its operation process is as follows: (1) Based on the groundwater depth, surface and subsurface salt content, and soil profile mechanical composition, the plots are screened to generate qualified plots in the initial screening.

[0024] In this step, the present invention is applicable to severely saline-alkali land with shallow groundwater, high sand content in the soil profile, and significant salt accumulation. Therefore, when conducting the initial screening of the plot, the following conditions must be met: 1) The groundwater depth is no more than 1.5m, preferably in the range of 1.0m-1.5m, and more preferably in the range of 1.0m-1.2m; 2) There is significant salt accumulation in the 0cm-20cm surface monitoring layer and the 20cm-40cm subsurface monitoring layer; To unify the expression of the position of each layer, the original ground surface after leveling before ridging is used as the reference surface, denoted as: z0=0; 3) The mechanical composition of the soil profile is mainly composed of sand particles.

[0025] In an optional embodiment of the present invention, the groundwater depth threshold Gc can be used as the basis for determining shallow groundwater: when the groundwater depth G in a certain area is ≤1.5m, it is determined that the present invention is applicable and it is classified as a qualified plot in the initial screening; when the groundwater depth G in a certain area is ≤1.2m, it is further determined that the risk of salt replenishment in the area is relatively strong, and it is still included in the qualified plot in the initial screening.

[0026] (2) Set up several survey points in the qualified plots in the initial screening, obtain the groundwater depth, salinity index and organic matter content parameters of each survey point, and make preliminary zoning based on the parameter characteristics.

[0027] This step is the first-level survey (rapid surface survey). It involves acquiring groundwater depth, salinity, and organic matter content parameters at each survey point, and then using these parameters to establish preliminary zoning. The purpose of the first-level survey is to identify the spatial differentiation characteristics of initially qualified plots for preliminary zoning, without requiring complete soil profile sampling at every survey point. Specifically, within the initially qualified plots, several survey points are laid out using a checkerboard or regular grid method, with a spacing of 20m-50m between each point. The parameters measured in the first-level survey include: 1) groundwater depth G; 2) salinity of the 0cm-20cm surface monitoring layer. ;3) Salinity index of the 20cm-40cm subsurface monitoring layer ; 4) Organic matter content (OM) of the 0cm-20cm surface monitoring layer; 5) Soil bulk density (ρ) of the 0cm-20cm surface monitoring layer can be measured if necessary; Specifically, the salinity index of the 0cm-20cm surface monitoring layer is used to characterize the salinity status of the salt return sensitive layer and the cultivated surface layer; the salinity index of the 20cm-40cm subsurface monitoring layer is used to characterize the salinity status of the layers below the surface and adjacent to the main root layer. Therefore, after the primary survey is completed, the initially qualified plots are divided into several preliminary zones or operational units based on the spatial adjacency and parameter similarity (parameter characteristics) of the survey points.

[0028] (3) Select representative profile points in each preliminary zone, test the soil profile parameters of each representative profile point, screen the preliminary zones with uniform sandy characteristics, and obtain several improvement operation zones. This step is the secondary survey (i.e., representative profile verification). The purpose of the secondary survey is to: 1) verify whether the zone possesses homogeneous sandy characteristics; 2) clarify the salinity distribution characteristics of the soil profile; 3) determine the lower boundary depth of the main root activity layer; and 4) provide a basis for the three-layer functional configuration design. Specifically, 2–3 representative profile points are selected within each preliminary zone, and stratified sampling is conducted on the 0cm–60cm soil layer (soil profiles at different depths), which can be extended to 0cm–80cm if necessary. The soil profile parameters measured at each representative profile point include: 1) mass fraction of sand, silt, and clay particles in each layer; 2) salinity index in each layer; 3) bulk density in each layer; 4) organic matter content in each layer; and 5) lower boundary depth of the main root activity layer. Simultaneously, for each preliminary zone… Based on the primary survey points and secondary representative profile points included, representative soil profile parameters for each zone are formed using average, weighted average, or spatial interpolation methods. The final representative soil profile parameters include: 1) the first... Groundwater depth in each preliminary zone ;2) No. Organic matter content of the surface monitoring layer in the preliminary partition ;3) No. Soil unit weight of the surface monitoring layer in the preliminary zoning area ;4) No. Salinity index of the 0cm-20cm surface monitoring layer in the preliminary zone ;5) No. Salinity indicators of the 20cm-40cm subsurface monitoring layer in the preliminary zone. ;6) No. The lower boundary of the main root activity layer of crops in the preliminary zoning .

[0029] Furthermore, the purpose of determining the homogeneous sandy texture is to screen the applicable objects of the present invention and to determine whether the region can be uniformly configured as a single partition; wherein, preliminary partitions that do not possess homogeneous sandy texture characteristics are not considered as objects of the present invention. Specifically, the process of screening preliminary partitions that possess homogeneous sandy texture characteristics is as follows: Let the first The first preliminary partitioning in the The mass fraction of sand particles in each soil profile section is: The corresponding layer thickness is The weighted average sand content of this preliminary partition is... for:

[0030] In the formula, Initial partition numbering; Numbering of soil profile sections; For the first The first preliminary partition The thickness of each soil layer section in the profile; For the first Weighted average sand content of each preliminary zone.

[0031] Calculate the difference between the maximum and minimum mass fraction of sand particles in this preliminary partition:

[0032] In the formula, For the first The difference between the maximum and minimum mass fraction of sand particles in each preliminary zone; For the first The maximum mass fraction of sand particles in each preliminary zone; For the first The minimum mass fraction of sand particles in each preliminary zone.

[0033] A zone is considered to have homogeneous sandy characteristics when it simultaneously meets the following conditions: 1) Weighted average sand content ≥70%, preferably ≥75%; 2) Difference ≤15 percentage points, preferably ≤10 percentage points; Therefore, the initial zones with homogeneous sandy characteristics will be used as improvement zones for subsequent operations.

[0034] (4) Based on the soil profile parameters, the functional types of each improvement operation zone are divided into salt replenishment risk-dominated zones, root zone vulnerability-dominated zones, and collaborative restricted zones.

[0035] This step only classifies the functional types of improvement zones with homogeneous sandy characteristics, including three categories: salt replenishment risk-dominated zones, root zone vulnerability-dominated zones, and cooperative-restricted zones; specifically: 1) When the first Each improved task partition simultaneously satisfies: , If so, the partition is determined to be a salt replenishment risk-dominated partition; among which, To improve the work area numbering, For the first Groundwater depth in each improved work zone For the first The salinity index of the 0cm-20cm surface monitoring layer in each improved work zone. The salinity threshold for the surface monitoring layer is preferably 4000 μS / cm, and this threshold should be determined based on the same salinity measurement method and remain consistent throughout the text. 2) When the first Each improved task partition simultaneously satisfies: , , If so, the partition is determined to be a root-area fragile-dominant partition. For the first Organic matter content of the surface monitoring layer in each improved work zone The threshold for organic matter content. For the first Soil unit weight of the surface monitoring layer in each improved work zone. This represents the soil unit weight threshold. For the first The weighted average sand content of each improved work zone The threshold value for sand content; where: ; ; Furthermore, the purpose of identifying this zoning is to screen areas with insufficient organic matter, weak water and fertilizer retention capacity, and obvious high sandy characteristics. 3) When the same improvement operation zoning simultaneously meets the criteria for salt supplementation risk-dominated and root zone vulnerability-dominated, it is determined to be a synergistically restricted zoning.

[0036] (5) Based on the depth of the lower boundary of the main root activity layer of crops, crops are classified into shallow-rooted crops, medium-rooted crops, and deep-rooted crops; In this step, according to the first The lower boundary depth of the main root activity layer of crops in each functional zone Crops are classified as: shallow-rooted crops: ;Medium-rooted crops: Deep-rooted crops: .in, Number the functional partitions; Step 2: Divide the soil profile of each functional zone into a surface salt control and drainage layer, a root zone suitable layer, and a lower salt-blocking and regulating layer.

[0037] This step determines the spatial relationship (i.e., their location within the soil profile) of the surface salt-controlling and draining layer, the root zone suitable layer, and the lower salt-blocking and regulating layer. It should be noted that the surface salt-controlling and draining layer primarily functions through terraced ridge-furrow micro-topography, surface cover, and surface water and salt redistribution; the root zone suitable layer primarily functions through root zone soil improvement, fertilization, and water and fertilizer retention. Therefore, these two layers may have some functional overlap within the surface area, but their functions differ. The lower salt-blocking and regulating layer is explicitly located below the root zone suitable layer and does not overlap with the previous two layers. Based on this, the locations of the surface salt-controlling and draining layer, the root zone suitable layer, and the lower salt-blocking and regulating layer are determined as follows: First, determine the surface salt control and drainage layer, which is composed of trapezoidal ridges and furrows. The parameters of the trapezoidal ridges and furrows include: 1) ridge height. , For the first 1) Ridge height of each functional zone; 2) Ridge width , For the first 3) Width of the ridge in each functional zone; , For the first 4) Trench width; The width of the ridge under each functional zone; , For the first The trench width of each functional zone; where the ridge top elevation is + ,+ For the first The elevation of the top of the ridge in each functional zone; the elevation of the bottom of the trench is 0 or... , For the first The trench excavation depth for each functional zone, and when only ridging is performed without additional trench excavation, can be taken as follows: The parameter range for trapezoidal ridges is: , , ; Assume the proportion of the low-level buffer salt collection area is... ,but , For the first The proportion of low-level buffer salt collection areas in each functional partition; This indicates the proportion of the low-level buffer salt collection area in the total lateral width of a ridge-furrow configuration cycle, preferably... More preferably 0.25-0.35.

[0038] Secondly, the root zone suitable layer is determined. This root zone suitable layer is used to cover the main root activity range of the crop, specifically: Let the first The lower boundary depth of the main root activity layer of crops in each functional zone is: , No. The root buffer margin of each functional partition is The lower bound depth of the adaptable layer in the root region is:

[0039] In the formula, For the first The lower boundary depth of the adaptability layer of the root region in each functional partition is the vertical depth of the lower boundary from the reference plane; among which, Preferably, the diameter is 3cm-8cm, and more preferably 5cm.

[0040] The upper boundary depth of the adaptable layer in the root region is preferably the reference plane, i.e.:

[0041] In the formula, For the first The upper limit depth of the root zone adaptability layer of a functional partition.

[0042] Therefore, the thickness of the adaptable layer in the root zone is:

[0043] In the formula, For the first The thickness of the root zone adaptation layer of each functional partition.

[0044] Finally, the lower salt-barrier control layer was determined, specifically as follows: Let the first The retention spacing between the functional partitioned root zone adaptability layer and the lower salt-controlling layer The upper limit depth of the lower salt-controlling layer is:

[0045] In the formula, For the first The upper boundary depth of the salt-barrier control layer in the lower part of each functional partition is the vertical depth of the upper boundary from the reference plane; preferably, For shallow-rooted crops, 5cm-10cm is preferred; for medium- and deep-rooted crops, 10cm-15cm is preferred.

[0046] Let the thickness of the lower salt-barrier layer be... Then its lower bound depth is:

[0047] In the formula, For the first Thickness of the lower salt barrier control layer of each functional zone; For the first The lower boundary depth of the salt-barrier control layer in the lower part of each functional partition. Among them, The preferred size is 5cm-10cm.

[0048] Step 3: Optimize and regulate the parameters of the salt-blocking material in the lower salt-blocking control layer, the improved material in the root zone adaptation layer, and the surface salt-controlling and salt-discharging layer.

[0049] This step involves configuring the parameters of the salt-blocking material in the lower salt-controlling layer, the improvement material in the root zone adaptation layer, and the surface salt-controlling and desalination layer in a coordinated manner based on the dominant limiting factors of each functional zone; the operation process is as follows: (1) Configure the salt barrier material for the lower salt barrier control layer; assuming the salt barrier material type is... Its laying volume for:

[0050] In the formula: Salt barrier material The equivalent packing density; Functional partition Salt barrier material of the lower salt barrier control layer The coverage rate is preferably 0.80-1.00, more preferably 0.85-0.95; Functional partition Salt barrier material of the lower salt barrier control layer Moisture content; Salt barrier material The amount of paving.

[0051] (2) Configure materials for improving the root zone adaptation layer; Let the soil density of the suitable root zone be... The soil quality of the suitable layer in the root zone for:

[0052] In the formula, Functional partition Soil mass of the root zone suitable layer, in kg / mu; Functional partition The thickness of the root zone adaptation layer, in cm; Functional partition The unit weight of the soil in the root zone suitable layer is expressed in g / cm³. 3 .in, (Right now 66.7×10 1 (One mu is approximately equal to 667 square meters) is a comprehensive coefficient converted based on an area of ​​1 mu.

[0053] The target dry basis blending mass fraction of organic fertilizer materials is set at 100%. The target dry basis blending mass fraction of the calcium-containing modified material is ,but:

[0054]

[0055] In the formula: , Functional partitions The amount of organic fertilizer and calcium-containing amendments applied to the root zone's suitable growth layer; , Functional partitions The target dry basis mass fraction of organic fertilizer materials and calcium-containing amendment materials; , Functional partitions The moisture content of organic fertilizer materials and calcium-containing improvement materials.

[0056] Therefore, for root zone-dominated fragile areas, the target dry basis blending mass fraction of organic fertilizer materials should be increased. For zones where salt replenishment risk is the primary concern, increase the target dry-based blending mass fraction of calcium-containing modified materials. and coverage For synergistically restricted partitioning, simultaneously increase the target dry basis blending mass fraction of organic fertilizer materials. Target dry basis blending mass fraction of calcium-containing modified materials and coverage .

[0057] (3) Configure the parameters of the surface salt control and drainage layer; the surface salt control and drainage layer can be formed by the combined action of trapezoidal ridges, surface mulching, and local water-saving irrigation. Establish functional zones. The coverage rate of the film is The preferred concentration is 0.70-0.95, and more preferably 0.80-0.90. For salt replenishment risk-driven zones, priority should be given to increasing the proportion of low-lying buffer salt-collecting areas. With film coverage Collaborative restricted partitioning can simultaneously optimize the proportion of low-level buffer salt collection areas. , film coverage And local water supply parameters.

[0058] Step 4: Implement soil configuration for each functional zone after optimization and adjustment; The steps are as follows: Based on the decision results of steps two and three, the lower salt-controlling layer is laid, the root zone adaptability layer is improved, and the surface salt-controlling and salt-removing layer is constructed sequentially according to each functional zone; the operation process is as follows: For each functional zone, crops are placed, trenches or troughs are dug, salt-blocking material is laid in the lower salt-regulating layer, and backfilling is performed. Organic fertilizer material and calcium-containing amendment material for the root zone are added and mixed thoroughly, a surface salt-controlling and drainage layer is constructed, and a covering material for this layer is laid. Finally, a localized water-saving irrigation system is deployed to achieve the soil structure creation for severely saline-alkali land, namely: Positioning and layout → trenching or grooving → laying the lower salt-controlling layer → backfilling with soil → applying root zone improvement material and mixing it evenly → constructing trapezoidal ridges and trenches → laying surface covering material → setting up a local water-saving irrigation system. The lower salt-controlling layer should be laid within the designed layer area and should avoid significant intrusion into the root zone's suitable growth layer. The root zone improvement material should be mainly distributed within the root zone's suitable growth layer and should not be mixed into the lower salt-controlling layer on a large scale. The trapezoidal ridges and furrows should form a continuous micro-topographic structure and maintain a relatively stable relationship between the high-level planting area and the low-level buffer salt collection area.

[0059] Step 5: Obtain the parameters of each functional zone after the implementation of the soil configuration, control and adjust them, set up sampling points, and calculate the soil configuration and salinity control indicators of each functional zone to evaluate the soil configuration compliance and salinity control effect.

[0060] This step involves construction vector control, operational adjustment, and project acceptance for each functional zone of the soil configuration; the operation process is as follows: (1) After the soil configuration is implemented, conduct construction quality inspections on each functional zone. Inspection parameters should include at least: ridge height. ; Wide on the ridge ; Wide under the ridge ; trench width Low-level buffer salt collection area ratio The upper boundary depth of the lower salt-controlling layer ; Lower boundary depth of the lower salt-controlling layer Thickness of the lower salt barrier layer ; Coverage rate of film The allowable deviation for the interface position of the lower salt barrier layer is ±5cm; the allowable deviation for the thickness of the lower salt barrier layer is ±2cm; and the allowable deviation for the ridge height is ±3cm.

[0061] (2) Conduct operational adjustments; during the early stages of crop growth and the period of salt return sensitivity, track the changes in salinity in the 0cm-20cm surface monitoring layer and the 20cm-40cm subsurface monitoring layer of each functional zone. When surface salt return is enhanced, improve the integrity of the mulch film, adjust the frequency of local water supply, or strengthen the buffering effect of the trench; when the subsurface salinity does not decrease significantly, supplementary treatment can be taken for areas with substandard local configurations. (3) Conduct project acceptance and effect evaluation; Let the salinity index of the 0cm-20cm surface monitoring layer before implementation or as the untreated control be... The salinity index of the 0cm-20cm surface monitoring layer during the critical period after implementation is: The surface salt content reduction rate for: ;in, Number the functional partitions; Functional partition Salinity index of the 0cm-20cm surface monitoring layer before implementation or in the untreated control; Functional partition Salinity index of the 0cm-20cm surface monitoring layer during the critical period after implementation; Functional partition The rate of salt reduction in the 0cm-20cm surface layer.

[0062] Let the salinity index of the 20cm-40cm subsurface monitoring layer before implementation or in the untreated control be: The salinity index of the 20cm-40cm subsurface monitoring layer during the critical period after implementation is as follows: The rate of decrease in subsurface salinity for: ;in, Functional partition Salinity index of the 20cm-40cm subsurface monitoring layer before implementation or in the untreated control; Functional partition Salinity index of the 20cm-40cm subsurface monitoring layer during the critical period after implementation; Functional partition The rate of salt reduction in the 20cm-40cm subsurface layer.

[0063] A point is considered a qualified point when it simultaneously meets the following conditions: 1) The interface position and thickness of the lower salt barrier layer meet the design requirements; 2) The surface salt control and drainage layer configuration parameters meet the design requirements; 3) The salt reduction rate of both the surface and subsurface layers is not lower than the preset threshold.

[0064] Preferably, the surface salinity reduction rate and subsurface salinity reduction rate The percentage should not be less than 10%, and preferably not less than 15%.

[0065] Finally, the overall pass rate P for each region is calculated using the following formula:

[0066] In the formula, The number of qualified points; This represents the total number of sampling points. When P ≥ 80%, the functional zoning project is deemed to have passed acceptance. When P < 80%, the non-compliant areas should be re-inspected after taking measures such as supplementary laying, local reshaping, re-mixing, or re-laying of local water supply systems until the requirements are met.

[0067] Furthermore, to verify the effectiveness of the soil configuration construction method for shallowly buried groundwater-rich, sandy, and severely saline-alkali land proposed in this invention, the method was applied to maize crop cultivation in Hotan region of Xinjiang, as follows: (1) Overview of the test site The experimental site is located in the saline-alkali area of ​​Hotan Prefecture, Xinjiang, with soil type being homogeneous sandy moderately to severely saline-alkali soil. Preliminary investigation indicated that the groundwater depth at the experimental site was approximately 115 cm, and the target improvement layer was 0 cm–80 cm. Measurements showed that the soil profile was predominantly sandy, with a weighted average sand content of 78% in the 0 cm–80 cm soil layers, meeting the homogeneous sandy soil characteristics. Figure 2 As shown, the organic carbon content of the top 20cm soil layer ranged from 1.16 g / kg to 1.35 g / kg; the pH was approximately 9, and the electrical conductivity exceeded 4000 μS / cm. These results indicate that this plot exhibits both significant risks of continuous salinity replenishment in the lower part of the soil and a fragile root zone structure with poor adaptability in the middle and upper parts, classifying it as a typical synergistically restricted zoning.

[0068] Based on this, the method proposed in this invention was applied to severely saline-alkali farmland in Hotan region of Xinjiang, using maize as the experimental crop. Maize is a deep-rooted crop, and under the local conditions, its main root activity layer is relatively deep. To balance the growth space of the root zone and the need for lower salt retention, a plant-derived interlayer made of maize stalks was laid 50 cm below the surface, forming a lower salt-regulating layer to reduce the continuous upward movement of groundwater and its carried salts along the soil profile. Above the interlayer, organic manure was applied according to the preferred parameters of this invention and mixed with the topsoil to form a suitable root zone layer, which improves organic matter levels, soil structure, and enhances the water and fertilizer retention capacity of the root zone. A raised-ridge micro-topography was constructed on the surface, forming a relatively high planting area and a low-lying buffer salt collection area, constituting a surface salt-controlling and discharging layer to regulate the spatial distribution of surface water and salt and mitigate rhizosphere salt damage.

[0069] Meanwhile, conventional saline-alkali land maize planting methods (combined treatment of mulching, drip irrigation and application of organic fertilizer in the topsoil) were used as a control group to compare and verify the application effect of the method proposed in this invention on the severely saline-alkali farmland in Hotan, Xinjiang.

[0070] Final verification shows that the method proposed in this invention effectively reduces salt content by more than 50%, as follows: Figure 3 As shown; the method proposed in this invention effectively promotes crop germination and growth, as follows. Figure 4 As shown; the method proposed in this invention significantly increases crop yield (more than twice that of the control group), basically reaching the yield level of medium-yield maize fields, such as... Figure 5 As shown.

[0071] In summary, the soil configuration construction method for shallowly buried groundwater-rich, sandy, and severely saline-alkali land proposed in this invention achieves the following technical effects: 1. It has achieved an improvement from surface-level control to profile-level control. This invention is no longer limited to single treatment of the surface or topsoil. Instead, it constructs a three-layer synergistic structure of surface salt control and drainage layer, root zone suitable layer, and lower salt-blocking and regulating layer to reconstruct the water and salt migration path of the soil profile as a whole, thereby weakening the continuity of groundwater salt recharge from the source. 2. It has achieved an improvement from unified processing to precise partition configuration. This invention divides land parcels into zones based on parameters such as groundwater depth, salinity profile distribution, sand content, organic matter level, and crop root activity layer. It can distinguish between zones dominated by salt replenishment risk, zones dominated by root zone vulnerability, and zones with synergistic constraints, and carry out differentiated configuration based on these zones, thereby improving the pertinence and adaptability of soil configuration creation. 3. It has achieved an upgrade from the superposition of single measures to a three-layer synergistic configuration. This invention organizes three functional units—lower salt control and regulation, middle soil improvement and fertilization, and surface salt control and drainage—according to interface relationships and functional division of labor, so that they no longer exist in isolation, but form an overall soil structure with clear spatial relationships and collaborative logic.

[0072] 4. It has achieved an improvement from experience-based application to parameter-linked configuration. This invention provides quantitative control over the thickness of the root zone suitable layer, the thickness of the lower salt-controlling layer, the interface spacing, the ratio of the surface furrow to the top layer, the coverage rate, and the amount of amendment materials applied. It also links these controls with crop root characteristics, groundwater depth, sand content, and dominant risk type, which helps to improve the feasibility and repeatability of the scheme.

[0073] 5. It has enabled the transition from experience-based construction to a closed-loop system for project acceptance. This invention establishes a closed-loop process from plot identification, configuration, construction implementation to effect acceptance by setting indicators such as configuration interface position, salt barrier layer coverage, surface configuration parameters, root zone salt reduction rate, and zoning qualification rate. This is beneficial to improving the stability of engineering quality in field promotion.

[0074] 6. More suitable for creating a long-term suitable environment in uniform sandy, severely saline-alkali land.

[0075] For severely saline-alkali land with high sand content, fragile structure, poor water and fertilizer retention capacity and significant risk of salt return, this invention can simultaneously reduce salt replenishment, improve the root zone environment and control surface salt return, thereby improving the stability and sustainability of the improvement effect.

[0076] Specific embodiments have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

[0077] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for constructing soil structure in shallowly buried, sandy, severely saline-alkali land, characterized in that, Includes the following steps: The land parcels were screened and initially divided into zones. Based on soil profile parameters, zones with homogeneous sandy soil characteristics were selected. Functional zones were then divided sequentially, and crop root system type classification was completed simultaneously. Specifically: Based on groundwater depth, surface and subsurface salinity, and soil profile mechanical composition, land parcels are screened to generate initially qualified parcels. Several survey points were set up within the initially qualified plots to obtain the groundwater depth, salinity index and organic matter content parameters of each survey point, and preliminary zoning was carried out based on the parameter characteristics. Representative profile points were selected within each preliminary zone, and the soil profile parameters of each representative profile point were tested. Preliminary zones with homogeneous sandy characteristics were screened to obtain several improvement operation zones. Based on soil profile parameters, each improvement operation zone is functionally divided into zones dominated by salt replenishment risk, zones dominated by root zone vulnerability, and zones with limited synergy. Based on the depth of the lower boundary of the main root activity layer, crops are classified into shallow-rooted crops, medium-rooted crops, and deep-rooted crops. The soil profile of each functional zone is divided into a surface salt-controlling and salt-discharging layer, a root zone suitable layer, and a lower salt-blocking and regulating layer. After optimizing and regulating the parameters of the salt-blocking material in the lower salt-blocking control layer, the improved material in the root zone adaptation layer, and the surface salt-controlling and salt-draining layer, the soil configuration of each functional zone is implemented. After the implementation of the soil configuration, the parameters of each functional zone are obtained, controlled and adjusted, and sampling points are set up to calculate the soil configuration and salinity control indexes of each functional zone in order to evaluate the soil configuration compliance and salinity control effect.

2. The method for constructing soil structure in shallowly buried, sandy, heavily saline-alkali land according to claim 1, characterized in that, The process of selecting preliminary zones with homogeneous sandy characteristics is as follows: Let the first The first preliminary partitioning in the The mass fraction of sand particles in each soil profile section is: The corresponding layer thickness is The weighted average sand content of this preliminary partition is... for: in, Initial partition numbering; Numbering of soil profile sections; For the first The first preliminary partition The thickness of each soil layer section in the profile; For the first Weighted average sand content of each preliminary zone; Calculate the difference between the maximum and minimum mass fraction of sand particles in this preliminary partition: in, For the first The difference between the maximum and minimum mass fraction of sand particles in each preliminary zone; For the first The maximum mass fraction of sand particles in each preliminary zone; For the first The minimum mass fraction of sand particles in each preliminary zone; Determine the weighted average sand content Is it greater than or equal to a preset sand content threshold, and what is the difference? If the initial zone is less than or equal to the preset quality difference, then the initial zone has the characteristics of uniform sand and is defined as an improvement zone; otherwise, the initial zone does not have the characteristics of uniform sand and is not processed.

3. The method for constructing soil structure in shallowly buried, sandy, heavily saline-alkali land according to claim 1, characterized in that, The process of dividing the soil profile of each functional zone into a surface salt-controlling and salt-discharging layer, a root zone suitable layer, and a lower salt-prevention and regulation layer is as follows: Determine the ridge height, ridge width, ridge width, and trench width for each functional zone, construct trapezoidal ridges and trenches, obtain the location of the surface salt-controlling and salt-discharging layer in the soil profile, and calculate the proportion of low-level buffer salt-collecting zones for each functional zone. Based on the functional zones as the lower boundary depth of the main root activity layer and the root buffer margin, the lower boundary depth of the suitable root zone is calculated, and the upper boundary depth of the suitable root zone is set as the reference surface. The thickness of the suitable root zone is calculated to obtain the position of the suitable root zone in the soil profile. The reference surface is the original ground surface after leveling before ridging. Set the retention distance between the root zone suitable layer and the lower salt-controlling layer for each functional zone, calculate the upper limit depth of the lower salt-controlling layer, set the thickness of the lower salt-controlling layer, calculate the upper limit depth of the lower salt-controlling layer, and obtain the position of the lower salt-controlling layer in the soil profile.

4. The method for constructing soil structure in shallowly buried, sandy, heavily saline-alkali land according to claim 1, characterized in that, The process of optimizing and regulating the parameters of the salt-blocking material in the lower salt-blocking control layer, the improved material in the root zone adaptation layer, and the surface salt-controlling and salt-draining layer is as follows: The salt barrier material of the lower salt barrier control layer is preset, and the amount of salt barrier material to be laid is calculated, i.e.: in, Number the functional partitions; It is a salt-barrier material type; Functional partition Salt barrier material of the lower salt barrier control layer The amount of material laid; Functional partition The thickness of the lower salt barrier layer; Salt barrier material The equivalent packing density; Functional partition Salt barrier material of the lower salt barrier control layer Coverage rate; Functional partition Salt barrier material of the lower salt barrier control layer Moisture content; Based on the soil unit weight of the root zone suitable layer, the soil mass of the root zone suitable layer is calculated, i.e.: in, Functional partition Soil quality in the root zone suitable layer; Functional partition The thickness of the root zone adaptation layer; Functional partition The soil density of the root zone's suitable growing layer; Based on the soil quality of the root zone's suitable growing layer, and combined with the target dry basis mass fraction of organic fertilizer and calcium-containing amendment, the application rates of organic fertilizer and calcium-containing amendment in the root zone's suitable growing layer are calculated, i.e.: in, , Functional partitions The amount of organic fertilizer and calcium-containing amendments applied to the root zone's suitable growth layer; , Functional partitions The target dry basis mass fraction of organic fertilizer materials and calcium-containing amendment materials; , Functional partitions The moisture content of organic fertilizer materials and calcium-containing amendment materials; Obtain the film coverage rate of the surface salt control and salt discharge layer and the proportion of the low-level buffer salt collection area; Ultimately, by regulating the coverage rate of salt-blocking materials in the lower salt-blocking control layer of different types of functional zones, the target dry basis mixing mass fraction of organic fertilizer materials and calcium-containing improvement materials in the root zone suitable layer, the film coverage rate of the surface salt-controlling and salt-draining layer, and the proportion of the low-level buffer salt collection zone, the optimal configuration of parameters for each functional zone is achieved.

5. The method for constructing soil structure in shallowly buried, sandy, heavily saline-alkali land according to claim 1, characterized in that, The process of implementing the soil configuration for each functional zone is as follows: For each functional zone, crops are placed, ditches or trenches are dug, salt-blocking materials are laid in the lower salt-controlling layer, soil is backfilled, organic fertilizer materials and calcium-containing amendment materials are placed in the root zone suitable layer and mixed evenly, a surface salt-controlling and salt-draining layer is constructed and covered with surface salt-controlling and salt-draining layer covering material, and finally a local water-saving irrigation system is deployed to realize the soil structure creation of severely saline-alkali land.

6. The method for constructing soil structure in shallowly buried, sandy, heavily saline-alkali land according to claim 1, characterized in that, The process of obtaining parameters for each functional zone after soil configuration implementation, controlling and adjusting them, setting up sampling points, and calculating soil configuration and salinity control indices for each functional zone to evaluate the effectiveness of soil configuration compliance and salinity control is as follows: The parameters of each functional zone were extracted and checked, including the thickness of the root zone suitable layer, the upper and lower boundary depths and thicknesses of the lower salt-controlling layer, the coverage of salt-controlling materials, the ridge width, the furrow width, the ridge thickness of the surface salt-controlling and salt-draining layer, the mulch coverage, and the layout of the local water-saving irrigation system. During the early stages of crop growth and the period of salt return sensitivity, the salt content of the surface monitoring layer and subsurface monitoring layer of each functional zone is tracked and investigated in real time. If surface salt return is enhanced, the coverage of salt-blocking materials, the frequency of local water supply, or the width of the trench is adjusted. Sampling points were set up in each functional zone. Based on the salinity index of the surface monitoring layer and subsurface monitoring layer after and before the implementation of the soil configuration, the salinity reduction rate of the surface monitoring layer and subsurface monitoring layer was calculated respectively. Determine whether the salt reduction rate of both the surface monitoring layer and the subsurface monitoring layer is not lower than the preset threshold. If so, the sampling point is a qualified point; otherwise, the sampling point is an unqualified point. Calculate the overall pass rate of each functional zone and determine whether the overall pass rate is greater than or equal to the preset threshold. If it is, the functional zone passes the acceptance test; otherwise, the functional zone fails the acceptance test.

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