A method for structural reconstruction and saline-alkali improvement suitable for saline-alkali farmland and application thereof

Abstract

The application belongs to the technical field of saline-alkali land improvement, and particularly relates to a structure reconstruction and saline-alkali improvement method suitable for saline-alkali farmland and application thereof. The application effectively improves soil structure, increases soil air permeability and water permeability, reduces salt concentration in soil, and further improves soil quality through measures such as soil improvement, water-salt regulation, salt spot ploughing layer reconstruction and leaching promotion. The optimized soil condition of the application provides a better growth environment for crops, which helps to improve the survival rate and yield of crops, and to enhance the growth environment of crops. The application integrates various improvement methods, can effectively manage different degrees of saline-alkali land, and has high adaptability and flexibility. Moreover, the application focuses on long-term effects, not only pays attention to short-term improvement effect, but also considers subsequent maintenance and management, which is beneficial to realize sustainable utilization of land resources.

Description

Technical Field

[0001] This invention belongs to the field of saline-alkali land improvement technology, specifically relating to a structural reconstruction and saline-alkali improvement method suitable for saline-alkali arable land and its application. Background Technology

[0002] Soil salinization is a widespread and severe problem in southern Xinjiang, posing a core constraint on local agricultural development. Saline-alkali land generally suffers from physical defects such as heavy soil structure, low porosity, and poor aeration and permeability. High salt content and unbalanced pH levels inhibit crop root development, hinder the absorption of soil moisture and nutrients, significantly increase the difficulty of field management, and directly result in low crop emergence rates and low yields. Furthermore, southern Xinjiang's arid climate with high evaporation rates allows soil salts to easily migrate upwards with capillary water and accumulate in the topsoil, resulting in irregular salt patches and making land reclamation and utilization extremely difficult. This severely hinders the resource utilization of arable land and the sustainable and high-quality development of agriculture in the region.

[0003] Currently, China has established four main improvement technology systems for saline-alkali farmland in southern Xinjiang: engineering, biological, agronomic, and chemical. These technologies are applied in accordance with local conditions in demonstration areas for saline-alkali land management in southern Xinjiang, such as Bachu County, forming large-scale practical solutions. Engineering measures include open ditch drainage, underground pipe salt removal, and vertical well irrigation combined with the dredging of main drainage channels. Open ditch drainage relies on mechanical or manual excavation of ditches, utilizing water level differences to leach soil salts out. Underground pipe salt removal technology has been implemented in Duolaitibag Township, completing the special treatment of 1,500 mu of saline-alkali land. In the upstream and downstream townships of the Yarkand River basin, 152 emergency drainage wells have been deployed, and 203.77 km of main drainage channels have been dredged simultaneously, constructing a regional gravity drainage network. Biological measures mainly rely on salt-tolerant plants to absorb and fix salt, inhibiting salt accumulation on the surface, and breeding new multi-resistant cotton varieties, establishing variety screening and demonstration planting bases. Agronomic measures include drip irrigation under mulch, brackish water irrigation, land leveling, sand covering with topsoil, and dry sowing followed by wet emergence of cotton, which improve field irrigation and drainage conditions by optimizing irrigation patterns, leveling the field surface, and improving soil quality. Chemical measures typically involve the application of organic fertilizers, acidic and neutral chemical fertilizers, and humic acid to optimize soil aggregate structure, regulate soil physicochemical properties, and reduce surface salinity.

[0004] Among existing improvement technologies, the mainstream technical solutions most closely related to the improvement conditions of this invention can be divided into two categories. The first category is traditional drainage combined with land leveling technology. This involves excavating drainage ditches and laying drainage pipes to lower the groundwater level, combined with mechanical land leveling to optimize the topsoil structure. This solution can quickly reduce shallow soil salinity and improve field conditions. However, due to local topographical differences, the drainage network has poor adaptability, and desalination is incomplete in areas with high groundwater levels. Furthermore, it can only improve the topsoil layer above 30cm, while deep, heavy clay soil layers are prone to repeated compaction, resulting in poor long-term improvement effects. The second category is chemical amendment combined with organic fertilizer improvement technology. This commonly uses desulfurized gypsum combined with organic fertilizer to adjust soil pH and replenish organic matter. This solution is fast-acting and can optimize soil fertility in the short term. However, chemical amendments can only temporarily change the chemical properties of the soil and cannot reconstruct the physical structure of the soil. The improvement effect is limited, and continuous application will significantly increase the cost of treatment, easily causing regional soil and water pollution and a heavy ecological burden.

[0005] Based on existing improvement technologies and similar solutions, the current saline-alkali land improvement industry in southern Xinjiang generally suffers from several unavoidable technical defects. Firstly, drainage systems rely on gravity drainage, lacking intelligent monitoring and control structures. Open ditches are prone to siltation and blockage, structural damage, and high maintenance costs. Drainage and salt leaching efficiency is low in severely saline-alkali plots, and salt patch treatment is uneven. Secondly, organic amendments decompose rapidly, requiring continuous external replenishment. This results in strong material dependence, high treatment costs, and insufficient long-term improvement performance. Thirdly, conventional deep tillage operations have limited improvement depth, only loosening the surface soil and failing to break down deep colloid barriers. Improper operations can also damage soil stability and induce waterlogging and salt return problems. Fourthly, salt-tolerant economic crops are scarce, and the research and development and promotion of new cotton varieties have long cycles, making it difficult to adapt to the planting needs of different salinity gradients and climates in southern Xinjiang.

[0006] In summary, existing improvement technologies suffer from several industry pain points, including weak drainage control capabilities, lack of deep soil improvement, short improvement time, poor adaptability, and high treatment costs. Single improvement methods cannot simultaneously address the needs of short-term desalination, long-term salt fixation, and soil structure reconstruction, and the overall improvement effect fails to meet the requirements for high-standard reclamation of arable land. Therefore, considering the unique soil conditions and climate characteristics of saline-alkali land in southern Xinjiang, developing a method for soil structure reconstruction and salinity improvement that integrates land leveling, deep soil reconstruction, graded water and salt regulation, and long-term ecological improvement has become an urgent need for technological development in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a method for structural reconstruction and salinity improvement of saline-alkali farmland and its application. This invention provides a comprehensive improvement technology system that integrates "fertile soil expansion + water and salt regulation + salt spot topsoil reconstruction and leaching promotion + land leveling", which can fundamentally solve the problem of soil salinization and improve the quality of farmland and crop productivity.

[0008] This invention provides a method for structural reconstruction and salinity improvement of saline-alkali farmland, comprising the following steps: 1) Construction of drainage ditches: Construct main drainage ditches and peripheral drainage ditches on the plot to be improved. The main drainage ditches and peripheral drainage ditches intersect each other perpendicularly in a grid pattern. Multiple peripheral drainage ditches are arranged in parallel at equal intervals and have the same slope. The distance between two adjacent peripheral drainage ditches is 20-30m. Multiple main drainage ditches have the same slope. The distance between two adjacent main drainage ditches is 70-80m. The main drainage ditches and peripheral drainage ditches are backfilled with 25-35cm of crushed straw from the bottom and covered with non-woven fabric to form a straw layer. The original soil is then backfilled from the straw layer upwards. The height of the backfilled original soil is 20cm higher than the ground surface. The main drainage channel located on one side of the plot to be improved is connected to multiple corrugated pipes and drainage ditches, which are parallel to the main drainage ditch. The multiple corrugated pipes are arranged in parallel, with a spacing of 75m between adjacent corrugated pipes. The drainage ditches are either the original drainage ditches of the plot to be improved or newly constructed drainage ditches. 2) Soil deep loosening and obstacle removal: Deep loosening is carried out on the plots where drainage ditches have been built by digging ditches. The depth of deep loosening is 0.5m, and the distance between two adjacent ditches is 0.5m. 3) Land leveling: Level the land after deep tillage and obstacle removal. The north-south elevation difference of the leveled land shall be within ±5cm, and the east-west elevation difference shall be within ±3cm. 4) Apply farmyard manure: Apply farmyard manure to the leveled land and plow it in the autumn of the year before planting crops; 5) Irrigation: ridging and irrigating the plots where farmyard manure has been applied.

[0009] Preferably, the saline-alkali arable land includes severely saline-alkali arable land, which has the following characteristics: soil salt content in the 60cm soil layer is 15~30g / kg, soil pH value is >8.5, the soil compaction layer is thick, the salt drainage channel is not smooth and the terrain is uneven; the thickness of the soil compaction layer is 1~3cm.

[0010] Preferably, the main drainage ditch has a depth of 0.8~1.0m, a bottom width of 0.4m, and an upper opening width of 0.6m; the peripheral drainage ditch has a depth of 0.8~1.0m, a bottom width of 0.4m, and an upper opening width of 0.6m.

[0011] Preferably, the slope of the main drainage ditch is 0.1% to 0.3%, and the slope of the peripheral drainage ditch is 0.1% to 0.3%.

[0012] Preferably, the corrugated pipe includes a DN150 PVC drainage pipe or a DN300 PVC drainage pipe; the burial depth of the corrugated pipe is 1.2m.

[0013] Preferably, each corrugated pipe is equipped with a water collection flower pipe at its water inlet end, and the outside of the water collection flower pipe is wrapped with non-woven fabric.

[0014] Preferably, the water collection pipe is 6m long, and the opening is made by drilling holes around the pipe wall. 10mm water-permeable holes, spaced 50mm apart, arranged in a floral pattern.

[0015] Preferably, the farmyard manure is compost obtained by piling up manure and urea as raw materials, wherein the volume ratio of manure to urea is 1 m³ / kg. 3 3 kg; the amount of compost applied is 1 m3 manure / acre, based on the volume of manure.

[0016] Preferably, the irrigation volume is 200 cubic meters per mu per irrigation, and the irrigation is carried out 2 to 3 times in total.

[0017] The present invention also provides the application of the above-described structural reconstruction and salinity improvement methods for saline-alkali arable land in improving arable land quality and / or crop productivity.

[0018] Beneficial effects: This invention effectively improves soil structure, increases soil aeration and permeability, and reduces soil salinity by implementing measures such as soil expansion, water and salt regulation, and salt patch topsoil reconstruction to promote leaching, thereby improving soil quality. Furthermore, the optimized soil conditions provide a better growing environment for crops, contributing to higher survival rates and yields, thus enhancing the crop growth environment. Compared to traditional large-scale application of chemical amendments, this invention employs a localized, precise treatment method, reducing the use of chemical substances, lowering costs, and minimizing environmental impact. Therefore, this invention integrates multiple improvement methods, effectively treating land with varying degrees of salinity and alkalinity, demonstrating high adaptability and flexibility. Moreover, this invention emphasizes long-term effects, considering not only short-term improvement results but also subsequent maintenance and management, promoting the sustainable use of land resources. Additionally, this invention reduces the use of environmentally harmful chemicals, relying more on natural processes and ecological methods to restore soil health. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.

[0020] Figures 1-3 This is a soil profile of Plot 4 in the Bachu County Agricultural Industrial Park before remediation in Example 1; Figure 4 This is a vertical distribution diagram of total salt in the soil in Example 1, where the horizontal and vertical axes are in units of g / kg and cm, respectively; Figure 5 This is a vertical distribution diagram of chloride ions in the soil in Example 1, where the units of the horizontal and vertical axes are g / kg and cm, respectively. Figure 6 This is a vertical distribution diagram of sodium ions in the soil in Example 1, where the units of the horizontal and vertical axes are g / kg and cm, respectively. Figures 7-15 This is a map showing the distribution of water-soluble salts at different soil depths in Example 1; Figures 16-17 This is a flowchart of the process of the improved method in Example 2; Figure 18 These are some construction drawings from the process of building the drainage ditch in Example 2; Figure 19 This is a diagram illustrating the preparation process of the organic fertilizer in Example 2; Figure 20 This is a diagram illustrating the process of applying farmyard manure in Example 2; Figure 21 This is a diagram showing the seepage status 10 days after irrigation in the spring of 2024 in Example 2; Figure 22 This is a diagram illustrating the watering process that began on February 15, 2025, in Example 2. Figure 23 This is a diagram illustrating the irrigation situation on February 16, 2025, in Example 2. Figure 24 This is a diagram showing the completion of irrigation on February 17, 2025, in Example 2; Figure 25 The image is taken by a drone on February 18, 2025, the first day after irrigation was completed in Example 2. Figure 26 This is a diagram illustrating the opening of the valve to begin drainage on February 20, 2025, in Example 2. Figure 27 This is a diagram illustrating the waiting period for water to begin flowing out of the seepage culvert in Example 2 on February 21, 2025. Figure 28 This is a diagram illustrating the significantly reduced seepage and drainage volume on February 22, 2025, in Example 2. Figure 29 This is a diagram illustrating the reduced seepage and drainage volume on February 23, 2025, in Example 2. Figure 30 This is a diagram showing the soil salinity at different soil depths before irrigation in 2025 in Example 3. Figure 31 This is a sampling potential distribution diagram for 2025 in Example 3; Figure 32 This is a diagram showing the soil salinity at different soil depths after cotton harvest in 2025, as shown in Example 3. Figure 33 This is a trend diagram of soil surface salt content in cotton at different growth stages in 2025, as shown in Example 3. Figure 34 This is a diagram showing soil salinity at different soil depths from 2024 to 2025 in Example 3. Figures 35-37 Soil salinity at different soil depths after cotton harvest in 2025, as shown in Example 3; Figures 38-39 This is a map showing the NDVI distribution of Plot 4 in the Bachu County Agricultural Industrial Park from 2024 to 2025 in Example 3. Figure 40 The image shows the vegetation cover of Plot 4 in the Bachu County Agricultural Industrial Park from 2024 to 2025 in Example 3, with the left image representing 2024 and the right image representing 2025. Detailed Implementation

[0021] This invention provides a method for structural reconstruction and salinity improvement of saline-alkali farmland, comprising the following steps: 1) Construction of drainage ditches: Construct main drainage ditches and peripheral drainage ditches on the plot to be improved. The main drainage ditches and peripheral drainage ditches intersect each other perpendicularly in a grid pattern. Multiple peripheral drainage ditches are arranged in parallel at equal intervals and have the same slope. The distance between two adjacent peripheral drainage ditches is 20-30m. Multiple main drainage ditches have the same slope. The distance between two adjacent main drainage ditches is 70-80m. The main drainage ditches and peripheral drainage ditches are backfilled with 25-35cm of crushed straw from the bottom and covered with non-woven fabric to form a straw layer. The original soil is then backfilled from the straw layer upwards. The height of the backfilled original soil is 20cm higher than the ground surface. The main drainage channel located on one side of the plot to be improved is connected to multiple corrugated pipes and drainage ditches, which are parallel to the main drainage ditch. The multiple corrugated pipes are arranged in parallel, with a spacing of 75m between adjacent corrugated pipes. The drainage ditches are either the original drainage ditches of the plot to be improved or newly constructed drainage ditches. 2) Soil deep loosening and obstacle removal: Deep loosening is carried out on the plots where drainage ditches have been built by digging ditches. The depth of deep loosening is 0.5m, and the distance between two adjacent ditches is 0.5m. 3) Land leveling: Level the land after deep tillage and obstacle removal. The north-south elevation difference of the leveled land shall be within ±5cm, and the east-west elevation difference shall be within ±3cm. 4) Apply farmyard manure: Apply farmyard manure to the leveled land and plow it in the autumn of the year before planting crops; 5) Irrigation: ridging and irrigating the plots where farmyard manure has been applied.

[0022] In one embodiment, the saline-alkali arable land includes severely saline-alkali arable land, which has the following characteristics: soil salt content within a 60cm soil layer is 15-30g / kg, soil pH value > 8.5, thick soil compaction layer, poor salt drainage, and uneven terrain. In one embodiment, the saline-alkali arable land described in this invention can be saline-alkali arable land in Xinjiang; in another embodiment, the saline-alkali arable land is loam or clay. For example, in the severely saline-alkali arable land of this embodiment, the soil is loam, and there is a 20cm thick clay impermeable layer below the topsoil, hindering soil permeability, resulting in severe surface salt accumulation, significant barrier between the topsoil and the underlying layer, and poor drainage. In another embodiment, the thickness of the soil compaction layer described in this invention can be 1-3cm.

[0023] In one embodiment, the depth of the main drainage ditch is 0.8~1.0m, and more specifically, 1.0m; the bottom width of the main drainage ditch is 0.4m; and the top width of the main drainage ditch is 0.6m. In another embodiment, the depth of the peripheral drainage ditch is 0.8~1.0m, and more specifically, 1.0m; in yet another embodiment, the bottom width of the peripheral drainage ditch is 0.4m; and the top width of the peripheral drainage outlet is 0.6m.

[0024] In one implementation, the slope of the main drainage ditch is 0.1% to 0.3%, and more specifically, 0.2%; the slope of the peripheral drainage ditch is 0.1% to 0.3%, and more specifically, 0.2%. In this invention, the depth settings of the main drainage ditch and peripheral drainage ditch ensure that the crop roots are not harmed by salt.

[0025] In one embodiment, the corrugated pipe includes a DN150 PVC drainage pipe or a DN300 PVC drainage pipe, and more specifically, a DN150 PVC drainage pipe; the burial depth of the corrugated pipe is 1.2m. In another embodiment, each corrugated pipe is equipped with a water collection spout at its inlet end, and the outside of the water collection spout is wrapped with non-woven fabric; further, the pore size of the non-woven fabric can be 40 mesh. In another embodiment, the length of the water collection spout is 6m, and the opening specification is that the pipe wall is perforated around the perimeter. 10mm water-permeable holes, spaced 50mm apart, arranged in a floral pattern.

[0026] In one embodiment, the farmyard manure is compost obtained by piling up manure and urea as raw materials, wherein the volume ratio of manure to urea is 1 m³ / kg. 3 3 kg; the amount of compost applied is 1 m³ based on the volume of manure.3 Feces per acre.

[0027] In one implementation method, the amount of water used for irrigation is 200 cubic meters per mu per irrigation, and a total of 2 to 3 irrigations are performed. In this invention, when irrigating for the next time, the water injected in the previous irrigation must have completely infiltrated and there must be no standing water on the ground.

[0028] As one implementation method, the structural reconstruction and salinity improvement method for saline-alkali farmland described in this invention also includes laying drip irrigation pipes on the improved land. The constructed drainage ditch system, combined with drip irrigation salt control technology, improves drainage efficiency, reduces unnecessary water evaporation and waste, and more effectively controls the salt concentration in the soil.

[0029] In this invention, deep tillage breaks up the hard, compacted layer formed by rotary tillage, improving soil aeration and water permeability, promoting root development, conserving water, enhancing drought and flood resistance, improving soil structure, and increasing soil fertility. Combining this with the construction of drainage ditches, the practice of burying straw at the bottom of the ditches restructures the soil, further enhancing the aeration and water permeability of deeper soil layers and preventing soil compaction. This method not only improves the surface soil but also penetrates deep into the soil, achieving long-term soil improvement.

[0030] This invention also provides the application of the above-described structural reconstruction and saline-alkali improvement methods for saline-alkali farmland in improving farmland quality and / or crop productivity. This invention not only overcomes the problems of low drainage efficiency, difficulty in deep soil improvement, and environmental issues arising from relying solely on chemical amendments in traditional methods, but also achieves comprehensive improvement of soil quality and sustainable development through the integrated application of multiple improvement methods.

[0031] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0032] Example 1 Soil properties and saline-alkali environment survey of severely saline-alkali reclaimed land in Xinjiang The land to be restored in this embodiment is the brick factory land in Saikesan Village, Bachu Town, Bachu County, Kashgar Prefecture, Xinjiang (hereinafter referred to as Plot No. 4 of Bachu County Agricultural Industrial Park). Its soil profile is shown in the figure below. Figures 1-3 As shown.

[0033] In March 2024, basic surface soil samples were collected from the demonstration area in Bachu County to test soil nutrients, exchangeable ions, trace elements, heavy metals, salinity, and eight major ions. Profile samples were tested for water-soluble salts and the eight major ions. After harvest, soil pH, water-soluble salts, electrical conductivity, hydrolyzable nitrogen, available phosphorus, available potassium, organic matter, and total nitrogen were measured. Tables 1-5 were used to analyze soil limiting factors in the core demonstration area of ​​saline-alkali land.

[0034] Table 1 Nutrient Grading Standards

[0035] Table 2 Salt content grading standards

[0036] Table 3. Standards for Grading the Abundance and Deficiency of Trace Elements

[0037] Table 4 pH value grading standards

[0038] Table 5 Soil Heavy Metal Classification Standards

[0039] (1) Analysis of the geochemical properties of severely saline-alkali cultivated land Salinity type: Based on the test data of soil samples from 0 to 100 cm depth, the average content of water-soluble salts was 20.55 g / kg, chloride ion content was 4.01 g / kg, sulfate ion content was 9.61 g / kg, and the equivalent ratio was 0.57, indicating a chloride-sulfate type of salinity. Calculated based on the cation equivalent ratio, the calcium-magnesium equivalent ratio was 2.85, and the potassium-sodium / calcium-magnesium equivalent ratio was 1.21, indicating a calcium-sodium type of saline-alkali soil.

[0040] Water-soluble salts: The electrical conductivity (EC) of the soil in the demonstration area is 6.95 ms / cm, the pH value is 8.18, the water-soluble salt content of the surface soil in the demonstration area is 27.5 g / kg, the sodium adsorption ratio is 2.70, the salt content is high, and it is a severely saline-alkali land.

[0041] Soil nutrients: Organic matter: 6.88 g / kg, level 5 in Table 1 (6~10 g / kg). Total nitrogen: 0.38 g / kg, the lowest level in Table 1 (<=0.5 g / kg). Hydrolyzable nitrogen (alkaline nitrogen): 37.4 mg / kg, level 5 in Table 1 (30~60 mg / kg). Available phosphorus: 2.9 mg / kg, the lowest level in Table 1 (<=3 mg / kg). Available potassium: 220 mg / kg, higher than the highest level in Table 1 (>200 mg / kg). The soil organic matter, total nitrogen, and available phosphorus contents are low, while the available potassium content is high.

[0042] Soil type: The soil texture is sandy soil and loamy sandy soil, which means that the soil particles are relatively large, the drainage is good but the fertilizer retention capacity is poor. The survey results are shown in Tables 6-9.

[0043] Table 6. Test Results of Foundation Samples from Plot 4 in the Park

[0044] Table 7. Results of exchangeable ion detection in surface soil samples.

[0045] Table 8. Results of Heavy Metal Detection in Topsoil Samples

[0046] Table 9. Results of Soil Salinity Testing in Profile Soil Samples

[0047] Soil cleanliness: Based on the heavy metal test results in Table 8 and referring to the risk screening values ​​in Table 6, it can be concluded that arsenic, mercury, lead, chromium, cadmium, and total nickel did not exceed their respective risk screening values.

[0048] Soil bulk density: The average soil bulk density is 1.43 g / cm³. 3 (As shown in Table 10), it has no adverse effects on crop growth.

[0049] Table 10 Soil bulk density and moisture content of Plot 4 in the park

[0050] (2) Evaluation of cultivated land quality According to the "Grading of Cultivated Land Quality" (GB / T33469-2016), the comprehensive index of cultivated land quality for each evaluation unit is calculated using the cumulative method. The formula for calculating the comprehensive index of cultivated land quality is: P = ∑(Fi × Ci) Where: P—Comprehensive index of arable land quality; Fi — the membership degree of the i-th evaluation metric; Ci — the combined weight of the i-th evaluation index.

[0051] Table 11 Soil Evaluation Indicators Before the Experiment

[0052] The farmland was assessed as being classified as Grade 10.

[0053] (3) Identification of obstacle factors The data from the profile samples show that salt accumulation on the surface is quite obvious in this demonstration area. A clay layer appears below 30cm, and the heavy clay texture of the soil hinders the downward movement of salt. Soil salinity gradually decreases with increasing depth.

[0054] Differences in salinity distribution at different depths ( Figures 4-15 As shown in the figure: There are significant differences in soil salinity distribution at different depths. Areas with higher salinity at some depths may have lower salinity at other depths. For example, at shallower depths of 0-10cm and 10-20cm, the salinity distribution is more complex, with relatively more high-salinity areas (pink and light pink) and a more dispersed distribution. However, at deeper depths of 30-40cm and below, the salinity distribution is relatively more uniform, with high-salinity areas relatively concentrated in certain specific locations.

[0055] Salt content variation trend: Generally, the distribution of salt content changes with increasing depth, but it is not a simple increase or decrease. For example, in some areas, the salt content first decreases and then increases from shallow to deep, while in other areas it may show the opposite trend.

[0056] Summary of soil limiting factors in the demonstration area: The soil electrical conductivity (EC) of the demonstration area is 6.95 mS / cm, the pH value is 8.18, the water-soluble salt content of the topsoil is 27.5 g / kg, the sodium adsorption ratio is 2.70, indicating high salt content and severe saline-alkali soil. The soil organic matter content is low, the soil structure is poor, it is muddy when wet and compacted when dry, the topsoil bulk density is 1.5, and the soil limiting layer appears between 30 cm and 90 cm, affecting the vertical movement of soil water and salt.

[0057] Example 2 Structural reconstruction and salinity improvement methods for severely saline-alkali reclaimed land in Xinjiang, with a process flow diagram as follows: Figures 16-17 As shown, the steps are as follows: 1. Construct drainage ditches (culverts + corrugated pipes): Construct a crisscrossing drainage ditch system, connecting it to the existing alkali drainage channels. The overall drainage ditch system forms a "well" shaped underground drainage system, with the specific layout as follows: 1) Overall layout: The entire site adopts a grid layout. The horizontal direction is east-west for drainage ditches, and the vertical direction is north-south for main drainage ditches. The grids intersect to form standard strip fields. A DN160 PVC water collection and drainage pipe is installed on the east side, which eventually connects to the alkali drainage canal.

[0058] There are six drainage ditches, 1 meter deep on the west side and 1.3 meters deep on the east side. Six 9-meter-long pipes, each 16 cm in diameter, are buried inside each ditch. Holes are drilled on the west side, spaced 5 cm apart, for a total length of 5 meters, and covered with non-woven fabric. Holes are drilled 1 meter deep on the east side and covered with non-woven fabric. A drainage ditch, 54 meters long and 60 cm wide, is dug every five ditches.

[0059] 2) Number and spacing of drainage ditches: 27 rows of drainage ditches are set from west to east, with equal spacing of 15m and a slope of 0.1% from west to east. 3 rows of main drainage ditches are set from south to north, with equal spacing of 70~80m and a slope of 0.1% from south to north.

[0060] The layout logic can be summarized as follows: 27 east-west drainage ditches and 3 north-south main ditches intersect perpendicularly to each other, forming a regular grid-like network. Groundwater and saline-alkali water from the fields flow down the slopes into the main drainage ditches.

[0061] 3) Standard cross-sectional parameters of the drainage ditches: The depth of the main drainage ditch is 1.0m, the bottom width is 0.4m, and the top width is 0.6m. The depth of the main drainage ditch is 1.0m, the bottom width is 0.4m, and the top width is 0.6m.

[0062] 4) Construction of the seepage prevention filter layer at the bottom of the ditch (uniform construction method for both the main ditch and the ditch): layer by layer from the bottom of the ditch upwards: first backfill the bottom of the ditch with 30cm thick crushed corn stalks, then backfill the top layer with the original soil in layers, leaving a 20cm margin on the surface. After natural settlement during winter or spring irrigation, the surface will be leveled and shaped to achieve the functions of filtering water, preventing siltation, preventing collapse, improving the durability of the drainage ditch, and preventing siltation from clogging the pipes later.

[0063] 5) DN150 PVC drainage pipe layout (along the main drainage ditch on the east side): Six pipes are installed along the main drainage ditch on the east side, running from west to east. The center-to-center spacing between pipes is 75m, and the total length of each individual drainage pipe is 45m. The pipe has an outer diameter of 160mm and a burial depth of 1.2m. The end connection is: the pipe outlet is directly connected to the existing alkali drainage ditch, so that the groundwater and saline water collected by the grid-shaped ditch network can be discharged in a unified manner.

[0064] 6) Inlet and collection pipe structure (standard configuration on the inlet side of each drain pipe): Each DN150 drain pipe is equipped with a collection pipe at the inlet end. The pipe is 6m long, and the opening specifications are as follows: holes are drilled around the pipe wall. The pipe has 10mm permeable holes with a spacing of 50mm, arranged in an interlaced pattern. The outside of the pipe is completely wrapped with 40-mesh non-woven fabric to collect seepage water from the main ditch and the drainage ditch, filter out mud, sand, straw and other debris, and prevent the pipe from becoming clogged.

[0065] 7) Water flow logic (complete water cycle): soil salinity seepage in the field → east-west drainage ditch (0.1% west-to-east slope) → flows into the north-south main drainage ditch (0.1% south-to-north slope) → 6 sets of DN150 water collection pipes + drainage pipes along the main ditch on the east side → flow into the original alkali drainage canal and be discharged off the site.

[0066] The construction process of the drainage system is as follows: surveying and setting out → trench excavation → slope measurement → manual adjustment of trench slope → straw purchase → straw stacking between trenches → straw loading → straw transportation → straw backfilling → laying non-woven fabric → manual backfilling → mechanical backfilling → tractor compaction → wrapping corrugated pipes with non-woven fabric → corrugated pipe installation → corrugated pipe backfilling. Some construction drawings are shown below. Figure 18 As shown.

[0067] 2. Deep loosening and obstacle breaking: Deep loosening and trenching are carried out along the north-south direction of the plot, with a trench depth of 0.5 m and a spacing of 0.5 m. The number of trenches is determined in combination with the spacing and the size of the plot (395 trenches were dug in this example). The purpose is to break up the channels between the topsoil and the lower layer, increase the permeability and aeration of the soil, ensure that the excess water can be quickly drained after winter irrigation, and ensure that there is no water accumulation on the surface of the field.

[0068] The process of deep soil loosening and obstacle removal is as follows: purchase of deep loosening equipment → tractor rental → test run of deep loosening tractor → depth test and trench spacing test → deep loosening of field → spot check of deep loosening depth → leveling of field by tractor.

[0069] Deep loosening of the soil increases its permeability and aeration, ensuring that residual water can be quickly drained after winter irrigation and preventing water accumulation on the field surface.

[0070] 3. Land leveling: Due to elevation differences in the north-south and east-west directions, the northern part of the plot has severe salt accumulation, necessitating land leveling work. Leveling standards: A high-horsepower tractor is used to drive a laser leveling machine to complete the work, so that the north-south difference in elevation of the leveled plot is within ±5cm and the east-west difference is within ±3cm, ensuring that the flatness of the ground meets the requirements for subsequent irrigation and drainage.

[0071] The land leveling process is as follows: surveying and setting out → leveling with a bulldozer on the field ridges → plowing and tilling with a high-horsepower machine → leveling with a laser leveler → measurement and acceptance (within ±5cm error).

[0072] 4. Apply farmyard manure: Purchase 400 cubic meters of cow manure, at 3 cubic meters per acre. One cubic meter of cow manure requires 3 kg of urea. After sprinkling with water, pile the manure and cover it with a tarpaulin (e.g., ...). Figure 19As shown), turn the soil over approximately every 10 days. Apply well-rotted fertilizer to the soil in the autumn of the previous year (e.g., Figure 20 As shown in the image, the tractor rolled into the soil.

[0073] 5. Irrigation measures: Use tractors to create ridges, irrigate at a rate of 200 cubic meters per mu, irrigate 3 times, and observe the seepage time.

[0074] 6. Effects before and after improvement 1) Irrigation situation in the spring of 2024: The seepage status 10 days after spring irrigation is as follows: Figure 21 As shown, the water did not seep into the ground for 15 days, and manual pumping was required to completely drain the spring irrigation water.

[0075] 2) Irrigation situation in the spring of 2025: February 15th: Watering begins at 13:00 in the afternoon, as... Figure 22 As shown; the irrigation situation on February 16th is as follows. Figure 23 As shown; watering was completed at 19:45 on February 17th. Figure 24 As shown; drone imagery from the first day after irrigation was completed on February 18th. Figure 25 As shown; the valve was not opened for drainage on February 19th; the valve was opened for drainage on February 20th, as... Figure 26 As shown, water was connected to each drainage pipe as a test object; on February 21, water was waited for seepage, and water began to flow out of the culvert, as... Figure 27 As shown; on February 22nd, while waiting for seepage, the drainage volume decreased significantly, as... Figure 28 As shown; February 23rd, waiting for seepage, drainage volume is small, such as... Figure 29 As shown.

[0076] Summary: Irrigation period: from 13:00 on February 15th to 19:45 on February 17th, with a 3-hour break in between. The total irrigation time was 51 hours and 45 minutes, with 200 cubic meters of water per mu (approximately 667 square meters). Ten days after irrigation, all the water had infiltrated to the surface.

[0077] Example 3 Technical plan for cotton cultivation in Plot No. 4 of the Agricultural Industrial Park in Bachu County, Kashgar Prefecture, Xinjiang, in 2025: I. Basic Information 1. Previous crops: cotton and corn.

[0078] 2. Variety selection: Zhongmian 125 (a conventional variety. Growth period of 130 days. Good seedling growth and steady growth in the middle and late stages. Compact plant type, cylindrical shape, plant height of 83.4cm, type I fruiting branches, purplish-red stems with hairs, and small, light green leaves).

[0079] 3. Monitoring indicators during the test: 1) Record the cotton sowing time, sowing amount, plant spacing, fertilizer application amount at each stage, cultivation time, application amount and spraying time of mepiquat chloride, and the use of other pesticides.

[0080] 2) Cotton growth stage observation: Observations are conducted at different growth stages of cotton, including sowing, seedling, budding, flowering and boll-forming, and boll-opening stages. Observation indicators include cotton plant height, stem diameter, number of flowers and bolls, flower and boll size, number of fruiting branches, number of bolls per plant, weight per boll, width of the four leaves from the bottom, boll shedding rate, chlorophyll content, and other growth indicators. After harvest, the dry matter accumulation and nitrogen uptake rate of cotton are measured.

[0081] 3) Soil collection and testing: Soil samples were collected at designated locations before sowing and during harvest. Surface samples were taken to measure soil alkalinity, total salt, pH, organic matter, total nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus, and available potassium.

[0082] 4) Cotton yield measurement: seed cotton yield, lint yield, lint percentage, etc.

[0083] II. Land preparation and sowing conditions 1. Planting pattern: 2.05m wide film, one film for six rows, 14 holes with side soil covering.

[0084] 2. Land preparation and sowing: The steps of (1) building drainage ditches, (2) deep loosening of soil, (3) leveling of land, (4) application of farmyard manure, and (5) irrigation are the steps in Example 2.

[0085] (6) Constructing a drip irrigation system: Construct it according to the local conventional layout habits and methods.

[0086] (7) Apply base fertilizer Apply base fertilizer on April 9th, using 40 kg of compound fertilizer per mu (N:P:K=18~18~18); from April 9th ​​to April 10th, plow (deep plowing 28~30cm) and harrow twice, and spray pendimethalin during this period to prevent weeds from spreading in the field.

[0087] 3. Sowing: Sowing was completed from April 11th to April 12th. Modified cotton sowing machinery suitable for dry sowing and wet emergence was used. The seeder's nozzle was a cross-shaped small pointed nozzle, 2.5cm in length. A 2.05-meter wide, ≥0.015mm thick plastic film was selected, along with a 0.015mm thickened wide film. For machine-harvested cotton, a "66cm + 13cm" configuration was used, with an average row spacing of 38cm, a single row length of 1754 meters per mu (approximately 667 square meters), and a 14-hole tray seeder with a plant spacing of 9.77cm, theoretically yielding 17957 plants per mu. One film and three irrigation pipes were used. Drip irrigation tape was a patch-type drip irrigation tape, laid in the middle of narrow rows. The machine used Beidou navigation for automatic driving, with side sealing, and a sowing depth of approximately 1.5cm.

[0088] 4. Drip irrigation for seedling emergence: Begin drip irrigation on April 14th, with the first drip irrigation volume being 25 cubic meters per mu (approximately 0.16 acres). 3 Apply 2 kg / mu of humic acid fertilizer via drip irrigation; apply a second drip irrigation on April 19th, with a drip volume of 20 m³ / mu. 3 Apply 2 kg / mu of humic acid fertilizer with water dripping.

[0089] III. Post-Management Plan 1. Seedling stage (emergence - around May 20th) management The main goal is to ensure that the seedlings are uniform, healthy, and free from pests and diseases.

[0090] (1) Soil sealing to conserve moisture: In cotton fields with side-sealed soil, the planting holes are not sealed with soil, making it easy for soil moisture to dissipate and for salts to rise and accumulate. At the 2-3 leaf stage, use an elevated winch soil sealing machine to seal the holes to conserve moisture and control weeds inside the film. The soil sealing thickness should be 1-1.5 cm, so as not to crush the seedlings. At this time, apply fertilizer with irrigation water, with 3 kg / mu of urea phosphate + 3 kg / mu of potassium dihydrogen phosphate.

[0091] (2) Seedling stage chemical control: Spray mepiquat chloride 1-2 times. The first time is at the 2-4 leaf stage, with a dosage of 0.8-1 gram per mu. If the internode length of the main stem is greater than 7 cm or the height of the main stem is greater than the plant width, carry out the second chemical control in a timely manner, with a dosage of 1-1.5 grams of mepiquat chloride per mu. Thrips should be controlled at the same time during chemical control. If there is continuous hot and dry weather, the number of thrips control should be increased appropriately.

[0092] (3) Weed control: From late April to early May, manual or chemical agents are used to control weeds in the field.

[0093] (4) Pest control: When 70% of the cotton seedlings have fully expanded cotyledons, apply preventative pest control once; apply preventative pest control once at the 2-leaf stage; and apply control once at the 4-5 leaf stage based on the pest situation. During control, spray protective strips along the field edges to reduce the base population of pests and prevent cotton aphids and spider mites from migrating and harming cotton fields. Strengthen the investigation of central aphid and mite plants. If central aphid or mite plants are found, surround and spray the affected areas, and strictly prohibit the application of pesticides to the entire field. When cotton aphids are spreading, use pesticides such as 50% flonicamid water-dispersible granules and 22.4% spirotetramat suspension for control; when cotton spider mites occur, use pesticides such as 20% pyridaben wettable powder and 30% etoxazole suspension for control; thrips can be controlled with pesticides such as 60 g / L spinosad suspension and 25% thiamethoxam water-dispersible granules.

[0094] 2. Management during the budding stage (around May 20th to June 15th) The goal is to ensure the cotton grows steadily, produces more buds, blooms earlier, and establishes a good foundation for high yield.

[0095] (1) Water and fertilizer management: Based on whether the cotton shows signs of drought, water twice, using the drip irrigation technique, fertilizing after each watering. Each drip irrigation should be done 10 days after budding, with a drip volume of 20-25 ml. 3Apply 7 kg / mu of urea, 6 kg / mu of monoammonium phosphate, and 1.5 kg / mu of potassium humate via drip irrigation. A second drip irrigation application should be performed 9 days later to ensure vigorous vegetative and reproductive growth of the cotton plants during the flowering period, with a drip irrigation volume of 20-25 ml. 3 Apply 8 kg / mu of urea + 10 kg / mu of compound fertilizer (or 10 kg / mu of monoammonium phosphate) per mu.

[0096] (2) Chemical regulation during the budding stage: Chemical regulation is carried out twice, at the 6-7 leaf stage and the 10-11 leaf stage, with 1-2 grams of chlormequat chloride sprayed per mu each time, to effectively control the internode length and prevent excessive growth of cotton.

[0097] (3) Pest and disease control: Focus on controlling cotton aphids, mirid bugs, cotton bollworms, and Fusarium wilt. For the spread of cotton aphids and mirid bugs, alternate spraying with 50% flonicamid water-dispersible granules, 25% thiamethoxam water-dispersible granules, and 22.4% spirotetramat suspension concentrate can be used for control. For cotton bollworms, maintain systematic investigation and monitoring, control the number of the first generation, and make full use of corn traps, pheromones, insecticidal lamps, etc. to attract and kill pests; use pesticides scientifically and rationally, spraying at the peak of egg production and treating before the third instar to control the density of the second and third generations.

[0098] 3. Management during the flowering and bell-forming period (June 16 - July 30) The main objectives are to prevent boll shedding, promote the formation of more bolls, increase the size of bolls, prevent boll rot, and prevent premature aging.

[0099] (1) Water and fertilizer management: Apply nitrogen fertilizer appropriately during the flowering and boll-forming stage, increase the application of phosphorus and potassium fertilizer, and supplement with micronutrient fertilizers such as boron and zinc. During this period, drip irrigation is required 5-7 times, with each drip irrigation covering 25-30 ml. 3 / mu, drip irrigation interval 8 days, the drip irrigation frequency needs to be increased in hot weather. Each time, apply 5-8 kg / mu of urea with irrigation. During the initial flowering to full bloom period, apply 10 kg / mu of high nitrogen and high phosphorus compound fertilizer + 2 kg / mu of potassium sulfate with irrigation each time. During the full bloom to boll formation period, apply 10 kg / mu of high phosphorus and high potassium compound fertilizer (or 6 kg / mu of monoammonium phosphate and 4 kg / mu of potassium sulfate) with irrigation each time.

[0100] (2) Timely topping: Topping should be completed before July 10. After topping, 9-10 fruit branches should be retained, and the natural height of the cotton plant should be controlled at 80-85cm. Manual topping should be used.

[0101] (3) Chemical regulation: First, chemical regulation during the flowering and boll-forming stage. Chemical regulation is carried out twice from flowering to topping. The first time is at the 12-13 leaf stage, with 2-3 grams of mepiquat chloride per mu. The second time is carried out 3 days before topping, with 2-3 grams of mepiquat chloride per mu. Second, chemical control after topping. Chemical control is required twice after topping. The first time is carried out 5-7 days after topping, with 5-7 grams of mepiquat chloride per mu. The second time is carried out 8-10 days after topping, with 8-12 grams of mepiquat chloride per mu.

[0102] (4) Pest control: Strengthen the control of cotton aphids, cotton bollworms, cotton spider mites, and thrips. For cotton bollworms, nucleopolyhedrovirus biological pesticides should be given priority. For chemical pesticides, 0.5% abamectin EC and 15% indoxacarb SC can be used in rotation. For cotton aphids, thrips, and cotton spider mites, the same pesticides should be used, and attention should be paid to alternating pesticides.

[0103] (5) Foliar fertilization: In order to improve the vitality of cotton pollen and photosynthesis, enhance the cotton's resistance to adverse conditions, maintain boll weight and improve cotton quality, foliar fertilizer can be sprayed 1-2 times during the flowering and boll-forming period, with 100 grams of boron fertilizer and 200 grams of potassium dihydrogen phosphate sprayed each time.

[0104] 4. Management during the fluffing period (August 1st - September 15th) The goal is to promote early maturity, prevent premature aging and delayed maturity, and improve fiber quality.

[0105] (1) Water and fertilizer management: Drip irrigation during the boll opening period can increase boll weight, but the amount of irrigation should not be too much, about 20 cubic meters per mu is appropriate, to avoid boll rot caused by excessive humidity in the cotton field. According to the boll development, fertilization should be stopped on August 25th, and drip irrigation should also be stopped on August 25th. For cotton fields with vigorous growth, irrigation should be stopped earlier, and for fields with poor soil water retention, the irrigation stop time should be appropriately delayed. According to the cotton growth, drip irrigation is generally carried out 3 times. The first drip irrigation is carried out with an amount of 20-25 cubic meters per mu and 10 kg of compound fertilizer per mu; the interval is 10 days. The second drip irrigation is carried out with an amount of 20-25 cubic meters per mu and 10 kg of compound fertilizer per mu; the third drip irrigation is carried out with an interval of 10 days, with an amount of 20 cubic meters per mu and 8 kg of compound fertilizer per mu.

[0106] (2) Chemical defoliation: When the cotton boll opening rate reaches 30-40%, apply defoliant. The average daily temperature should be maintained above 18℃ and the minimum nighttime temperature should not be lower than 12℃ for 7 days after defoliant application to ensure effective defoliation. Defoliant application should be completed before September 15th. Use a boom sprayer with a divider when applying defoliant, operating at a speed of 4-5 km / h to ensure even and thorough application. Defoliant can be applied using 54% thiamethoxam, 80% thiabendazole, etc., combined with ethephon for defoliation and ripening. For example, use 12-15 ml / mu of 54% thiamethoxam and 60-80 g / mu of ethephon, diluted with 40 kg / mu of water. If there are weather changes or poor defoliation results, conduct a second application after approximately 5-7 days. The use of drones for defoliant application is strictly prohibited.

[0107] 5. Harvest period management (1) Pre-harvest preparation: After water is stopped, the drip irrigation facilities should be dismantled and recycled in a timely manner, and weeds, hanging branches and residual film and obstacles should be removed to prepare for the cotton harvester to enter the field.

[0108] (2) Harvest at the appropriate time: When the cotton defoliation rate reaches 95% or more and the boll opening rate reaches 95% or more, harvest in a timely manner.

[0109] (3) Operational requirements: The cotton harvesting speed should be controlled at 3.5-5 km / h. The cotton cleanliness, moisture regain and impurity content should be checked in a timely manner. Harvesting should not continue if the moisture regain is >12%.

[0110] (4) Harvesting quality: The harvesting rate is above 93%, the cotton left behind is 3-5%, the cotton knocked down is 1-2%, the impurity rate is below 10%, and the seed cotton moisture content is ≤12%.

[0111] 6. Remove residual film After cotton harvest, a residual film recycling machine completes the entire process in one go, including straw return to the field, film removal, film application, impurity removal, film removal, and rolling or packing of residual film. The film recycling rate in farmland during the season should be over 85%, and the straw crushing length should be <10cm. When recycling residual film, the impurity content should be minimized to facilitate recycling. Residual film must be centrally processed and not piled up along field edges or roadsides to prevent secondary pollution.

[0112] IV. Disaster Prevention and Mitigation (a) Low-temperature damage: Based on medium- and long-term weather forecasts, adopt methods such as dry sowing and wet emergence to ensure that the seed germination period avoids low-temperature weather and prevents seed rot and seedling rot. For cotton fields that have just emerged, smoke around the field to prevent frost damage. After suffering from low-temperature damage, cotton fields with missing seedlings should be replanted while the soil is still moist; for fields with a seedling survival rate of less than 50%, reseed directly on the plastic film.

[0113] (II) Wind and Hail Disasters: Strengthen meteorological monitoring and use artificial weather modification to mitigate hail disasters. For cotton plants that have suffered hail damage during the budding stage and whose growing points have been broken, the topping time should be appropriately postponed; for cotton fields affected during the flowering and boll-forming stage, the water stoppage time should be reasonably postponed to make full use of existing green organs and strive for yield; for cotton fields with no harvest, timely replanting should be carried out to reduce disaster losses.

[0114] (III) High temperature disasters: Adjust the frequency of drip irrigation to increase the humidity of cotton fields and ensure water supply; apply appropriate topdressing to prevent premature aging; foliar spray plant growth regulators to enhance the resistance of cotton plants; strengthen the prevention and control of diseases and pests.

[0115] Technical plan for cotton cultivation in Plot No. 4 of the Agricultural Industrial Park in Bachu County, Kashgar Prefecture, Xinjiang in 2024: Cotton was cultivated according to the 2025 cotton cultivation management method, except that it was cultivated on plot No. 4 before the structural reconstruction and salinity improvement were carried out according to the steps in Example 2.

[0116] Comparison of the technical effects of cotton cultivation in Plot 4 of the Bachu County Agricultural Industrial Park, Kashgar Prefecture, Xinjiang in 2024 and 2025: I. Results of cotton emergence rate and yield 1. Emergence rate In 2024, the seedling emergence rate of plot No. 4 in the Bachu County Agricultural Industrial Park was 45%. In 2025, the average seedling emergence rate of plot No. 4 was 67%, which was 22 percentage points higher than the seedling emergence rate of the demonstration area in 2024 (45%), representing an increase of 48.9%.

[0117] 2. Production During the yield measurement in 2025, experts were invited to randomly select 5 sampling points, each with an area of ​​6.67m². 2 Count the number of cotton plants and the number of effective bolls at each sampling point, and calculate the weight of seed cotton with 30 bolls and the weight of a single boll. Calculate the average number of plants per mu and the average yield per mu based on the results of the five quadrats.

[0118] Table 12. Yield Measurement Results for Plot No. 4 in 2025

[0119] Table 13. Yield Measurement Results for Plot No. 4 in 2024

[0120] Tables 12-13 show that the average yield of seed cotton in the demonstration area in 2024 was 256.58 kg / mu. In 2025, the average yield of seed cotton in the demonstration area was 298.36 kg / mu, an increase of 41.78 kg / mu compared with the yield in 2024, representing a growth rate of 16.3%.

[0121] II. Soil salinity test results 1. Soil salinity at different depths before irrigation in 2025, as follows: Figure 30 As shown.

[0122] ① Overall salt levels are high, and spatial distribution is uneven. During sampling, the principle of even distribution within the plot was followed. Figure 31 Sampling was conducted at nine red locations. Surface soil samples were collected at the seedling, budding, flowering, and boll-opening stages. Before winter irrigation and after cotton harvest, soil profiles at depths of 0-5cm, 5-10cm, 10-20cm, 20-40cm, 40-60cm, and 60-100cm were collected at each location. Five biological replicates were collected at each location to test soil pH, water-soluble salt content, and electrical conductivity. The average soil salinity was 16.85 g / kg, far exceeding the salt tolerance threshold for most crops. The highest salinity value, 59.76 g / kg, was found at a depth of 60-100cm at location 3-3 in zone 3, indicating that this plot not only had high surface salinity but also severe deep soil salinity.

[0123] ②The differences between the three regions are enormous: The soil salinity in Zone 1 is relatively low overall, with an average salinity of 10.4 g / kg. The highest salinity is 14.6 g / kg in the 5-10 cm soil layer at points 1-4.

[0124] The salinity in Zone 2 is moderate, with an average of about 12.5 g / kg. The salinity in the topsoil (0-5 cm) at sampling point 2-1 reaches 34.2 g / kg, which is an extremely high value.

[0125] The soil salinity in Zone 3 is generally high, with an average salt content of up to 27.0 g / kg and a salt content of up to 47 g / kg in the 60-100 cm soil layer. This area is severely salinized and is no longer suitable for conventional agricultural planting.

[0126] ③ Salinity analysis of different soil layer thicknesses: Looking at the entire area of ​​Plot 4, the soil salinity exhibits a clear vertical distribution characteristic with depth. The overall trend is: higher salinity in the surface layer, decreasing in the middle layer, and highest in the deep layer. The average salt content is highest in the 0-5cm surface layer, reaching 19.48g / kg, indicating that this layer is significantly affected by evaporation, and salt accumulates on the surface. The average salt content is slightly lower in the 5-10cm layer, at 18.76g / kg, indicating that salt enrichment is mainly concentrated within the top 10cm. In the 10-20cm layer, the average salt content drops to 16.52g / kg, showing a clear downward trend. At a depth of 20-40cm, the salt content decreases to 12.05g / kg, the lowest among all soil layers, possibly related to past irrigation leaching or groundwater recharge, forming a relatively low-salt transition zone. In the 40-60cm soil layer, the salt content slightly increases, averaging 14.95g / kg. In the 60-100cm deep soil layer, the average salt content is 17.78g / kg, approaching or even exceeding the salt content of some surface soil layers, indicating that salt has accumulated in the deeper soil layers.

[0127] 2. Soil salinity at different soil depths after cotton harvest in 2025, as follows: Figure 32 As shown.

[0128] ① Overall trend: Soil salinity shows a significant decreasing trend with increasing depth, especially in the top 0-40cm soil layer where salinity is higher, while it decreases significantly below 40cm. The highest salinity occurs in 0-5cm (10.2g / kg), and the lowest occurs in 40-60cm (2.9g / kg).

[0129] ② Surface salt accumulation: The salt content in the 0-40cm soil layer remains at 7.7-10.2g / kg, possibly due to salt accumulation on the soil surface caused by evaporation and other factors. If leaching is not carried out after harvest or rainfall is low, salt is likely to accumulate on the surface.

[0130] ③ Deep soil (>40cm): The salinity was significantly reduced to <4g / kg, indicating that the salinity did not migrate downwards significantly and the area below the root zone was less affected by salinization.

[0131] After the autumn harvest in 2025, according to the reference standard for soil salinization level, the soil in plot No. 4 from 0 to 40 cm is classified as severely saline soil, while the soil below 40 cm is classified as light to moderately saline soil.

[0132] 3. The trend of soil surface salinity content in 2025 is shown in the figure below. Figure 33 As shown.

[0133] ① Analysis of the changing trend of soil salinity content Overall trend: Soil salinity increases from seedling stage to flowering stage, reaching a peak of 20.13 g / kg at flowering stage; then it gradually decreases from boll stage to a minimum of 14.44 g / kg at harvest.

[0134] Seedling stage → Flowering stage: Salt may accumulate in the soil surface layer due to strong evaporation, high mineralization of irrigation water, or poor drainage. Flowering stage → Harvest stage: Soil salinity gradually decreases as crop transpiration rate increases, or with rainfall or artificial salt leaching measures (irrigation to suppress salt).

[0135] ② Calculation of desalination rate Calculate the annual salt removal rate using the seedling stage as the initial value: Net desalination rate = (17.2-14.44) / 17.2×100%≈16.05%, and the results are shown in Table 14.

[0136] Table 14. Changes in desalination rate during the growing season (g / kg)

[0137] Throughout the cotton growing season, soil salinity exhibited a trend of "increasing first and then decreasing." Starting from the seedling stage (17.2 g / kg), salinity gradually increased, reaching its highest value of the year (20.13 g / kg) during flowering. Subsequently, soil salinity decreased significantly, dropping to 14.44 g / kg by harvest. This change suggests that in the early stages, factors such as evaporation, high irrigation water mineralization, or limited drainage conditions may have led to salt accumulation in the surface layer; while in the middle and later stages, effective desalination was achieved through natural leaching, crop transpiration regulation, or human management measures (irrigation to suppress salt).

[0138] Calculated from the peak salinity at the flowering period, the desalination rate of the soil surface reached 28.3% by the harvest period, indicating that the desalination rate of this plot was relatively high in the 2-3 months after the flowering period. The desalination process was not uniform, with the highest desalination rate from the boll opening period to the harvest period, reaching as high as 17.6% in a single stage.

[0139] Comparing the entire growth period, the net desalination rate from seedling stage to harvest was 16.1%, which is lower than the desalination rate after the peak, but still shows that the soil salinity generally decreased on an annual scale, indicating that the current integrated improvement model has a certain improvement effect on plot No. 4.

[0140] 4. Comparative analysis with basic soil data in 2024 ① Soil surface salt content Before the 2024 experiment, the water-soluble salt content of the topsoil was 27.5 g / kg. After the 2025 harvest, the water-soluble salt content of the topsoil was 14.44 g / kg, a decrease of 47.49%.

[0141] ② Soil profile salinity Soil salinity at different soil depths from 2024 to 2025 is shown in the figure below. Figure 34 As shown, soil salinity at different soil depths after cotton harvest in 2025 is as follows: Figures 35-37 As shown.

[0142] As can be seen, the temporal dynamics of salt content are as follows: From a time series perspective, the water-soluble salt content in the topsoil (0-5cm) exhibits significant seasonal fluctuations. In the spring of 2024, the salt content reached a high of 53.1 g / kg, indicating severe salt accumulation in the topsoil during this period. By the autumn of 2024, the topsoil salt content had plummeted to 8.19 g / kg, a decrease of 84.6%. In the spring of 2025, the salt content rebounded to 19.48 g / kg, while in the autumn of 2025 it further decreased to 15.61 g / kg. This indicates that although there is a seasonal trend of salt return, the overall salt level is significantly lower than the same period in 2024, demonstrating the significant effectiveness of the comprehensive improvement model applied to severely saline-alkali land.

[0143] Vertical distribution characteristics: A typical "surface-accumulation" salt distribution pattern was observed in all sampling periods, meaning the salt concentration decreased with increasing soil depth, particularly prominent in the spring of 2024 (0–5 cm: 53.1 g / kg; 60–100 cm: 12.8 g / kg). Over time, the vertical gradient flattened. In the autumn of 2025, the salt concentrations in the 0–5 cm and 60–100 cm layers were 15.61 g / kg and 12.48 g / kg, respectively, showing a significant narrowing of the difference. In the autumn of 2024 and the spring of 2025, the salt concentration in the 60–100 cm soil layer (12.04 g / kg and 17.77 g / kg, respectively) was slightly higher than that in the upper middle layer (40–60 cm soil layer).

[0144] Salinization Evolution Trend: Data from four phases show that the soil salinization level in the study area progressed from "high—low—medium—low." In the spring of 2024, the salinization was severe (>40 g / kg). Following the first year of soil improvement experiments, the salinity rapidly decreased and remained at a low to medium level (<20 g / kg). Although there was a return of salinity in the spring of 2025, the peak value was much lower than in 2024, and it declined again in the autumn, indicating that the saline-alkali land improvement measures implemented in the autumn of 2024 were effective.

[0145] III. Vegetation Index and Coverage, 2024-2025 NDVI distribution map as follows Figures 38-40 As shown in the figure. This embodiment selected NDVI images of plot No. 4 from four periods: August 31, 2024, and July 1, July 11, and August 5, 2025. Comparative analysis revealed that the vegetation cover in this area showed a year-on-year increasing trend. In the same period of 2024, NDVI values ​​were generally low, mainly concentrated in the range of 0.08 to 0.54, and there were many non-vegetated areas. However, data from the same period in 2025 showed a significant increase in NDVI values, especially during July and August, when the area of ​​high-value areas (NDVI > 0.54) expanded rapidly, and vegetation cover increased from approximately 50% to 85%. Combined with time series analysis, it can be seen that vegetation growth has a clear seasonal pattern, with summer being the peak growth period, and NDVI values ​​reaching above 0.80. Vegetation cover: 55 days after seedling emergence in 2024, the vegetation cover was 69.44%, and 55 days after seedling emergence in 2025, the vegetation cover was 79.15%.

[0146] It is evident that the structural reconstruction and salt-alkali improvement described in the above embodiments have the following advantages: 1. It helps to lower the groundwater level and reduce the accumulation of salt in the soil, thereby improving the permeability of irrigation and drainage efficiency.

[0147] 2. Improvement of soil structure: Engineering improvement measures, such as deep plowing and adding soil conditioners such as organic fertilizers, can improve soil structure, increase soil porosity, promote better water infiltration and retention, and benefit root growth.

[0148] 3. Enhanced salt leaching effect: Good irrigation management can carry excess salt in the soil below the root zone through the leaching action of water, preventing salt accumulation in the rhizosphere. Winter and spring are ideal times for salt leaching due to relatively low evaporation rates.

[0149] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for structural reconstruction and salinity improvement of saline-alkali farmland, characterized in that, Includes the following steps: 1) Construction of drainage ditches: Construct main drainage ditches and peripheral drainage ditches on the plot to be improved. The main drainage ditches and peripheral drainage ditches intersect each other perpendicularly in a grid pattern. Multiple peripheral drainage ditches are arranged in parallel at equal intervals and have the same slope. The distance between two adjacent peripheral drainage ditches is 20-30m. Multiple main drainage ditches have the same slope. The distance between two adjacent main drainage ditches is 70-80m. The main drainage ditches and peripheral drainage ditches are backfilled with 25-35cm of crushed straw from the bottom and covered with non-woven fabric to form a straw layer. The original soil is then backfilled from the straw layer upwards. The height of the backfilled original soil is 20cm higher than the ground surface. The main drainage channel located on one side of the plot to be improved is connected to multiple corrugated pipes and drainage ditches, which are parallel to the main drainage ditch. The multiple corrugated pipes are arranged in parallel, with a spacing of 75m between adjacent corrugated pipes. The drainage ditches are either the original drainage ditches of the plot to be improved or newly constructed drainage ditches. 2) Soil deep loosening and obstacle removal: Deep loosening is carried out on the plots where drainage ditches have been built by digging ditches. The depth of deep loosening is 0.5m, and the distance between two adjacent ditches is 0.5m. 3) Land leveling: Level the land after deep tillage and obstacle removal. The north-south elevation difference of the leveled land shall be within ±5cm, and the east-west elevation difference shall be within ±3cm. 4) Apply farmyard manure: Apply farmyard manure to the leveled land and plow it in the autumn of the year before planting crops; 5) Irrigation: ridging and irrigating the plots where farmyard manure has been applied.

2. The method for structural reconstruction and salinity improvement of saline-alkali farmland according to claim 1, characterized in that, The saline-alkali arable land includes severely saline-alkali arable land, which has the following characteristics: soil salt content in the 60cm soil layer is 15~30g / kg, soil pH value is >8.5, the soil compaction layer is thick, the salt drainage channel is not smooth and the terrain is uneven; the thickness of the soil compaction layer is 1~3cm.

3. The method for structural reconstruction and salinity improvement of saline-alkali farmland according to claim 1, characterized in that, The main drainage ditch has a depth of 0.8~1.0m, a bottom width of 0.4m, and an upper opening width of 0.6m; the peripheral drainage ditch has a depth of 0.8~1.0m, a bottom width of 0.4m, and an upper opening width of 0.6m.

4. The method for structural reconstruction and salinity improvement of saline-alkali farmland according to claim 1, characterized in that, The slope of the main drainage ditch is 0.1% to 0.3%, and the slope of the peripheral drainage ditch is 0.1% to 0.3%.

5. The method for structural reconstruction and salinity improvement of saline-alkali farmland according to claim 1, characterized in that, The corrugated pipe includes a DN150 PVC drainage pipe or a DN300 PVC drainage pipe; the burial depth of the corrugated pipe is 1.2m.

6. The method for structural reconstruction and salinity improvement of saline-alkali farmland according to claim 1 or 5, characterized in that, Each corrugated pipe is equipped with a water collection flower pipe at its inlet end, and the outside of the water collection flower pipe is wrapped with non-woven fabric.

7. The method for structural reconstruction and salinity improvement of saline-alkali farmland according to claim 6, characterized in that, The water collection pipe is 6m long, and the opening specifications are as follows: holes are drilled around all four sides of the pipe wall. 10mm water-permeable holes, spaced 50mm apart, arranged in a floral pattern.

8. The method for structural reconstruction and salinity improvement of saline-alkali farmland according to claim 1, characterized in that, The farmyard manure is compost obtained by piling up manure and urea as raw materials, wherein the volume ratio of manure to urea is 1 m³ / min. 3 3 kg; the amount of compost applied is 1 m³ based on the volume of manure. 3 Feces per acre.

9. The method for structural reconstruction and salinity improvement of saline-alkali farmland according to claim 1, characterized in that, The irrigation volume is 200 cubic meters per mu per irrigation, and a total of 2 to 3 irrigations are carried out.

10. The application of the structural reconstruction and saline-alkali improvement method for saline-alkali arable land according to any one of claims 1 to 9 in improving arable land quality and / or crop productivity.

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