Water-saving and salt-reducing synergistic regulation method for intercropping of salt-tolerant maize and halophyte

Abstract

This invention relates to the field of agricultural technology, specifically to a water-saving and salt-reducing synergistic regulation method for intercropping salt-tolerant maize with halophytes, comprising the following steps: Step 1: Saline-alkali land classification and pretreatment; Step 2: Construction of a gradient intercropping system; Step 3: Dynamic irrigation and drainage and water and fertilizer regulation; Step 4: Rhizosphere improvement; The saline-alkali land classification of this invention is based on the total salt content and pH value of the topsoil layer (0-20cm) (moderate 0.3wt%-0.6wt%, severe >0.6wt%), rather than the original 0-60cm depth, which is closer to the actual salt damage range of the topsoil layer and provides a precise basis for the implementation of subsequent measures; The intercropping system enhances the ecological diversity of farmland and avoids the ecological monoculture caused by monoculture; The technical solution expands the arable land resources of moderate and severe saline-alkali land, while conforming to the direction of green governance, and providing a replicable guarantee solution for saline-alkali areas.

Description

Technical Field

[0001] This invention relates to the field of agricultural technology, specifically to a water-saving and salt-reducing synergistic regulation method for intercropping salt-tolerant corn with halophytes. Background Technology

[0003] Current saline-alkali land management technologies have many limitations: most solutions lack targeted treatment, and a uniform management model is used for light, medium and severe saline-alkali areas, resulting in excessive improvement and waste of resources in lightly affected areas, and insufficient treatment in severely affected areas, making it difficult to meet standards; the layout of intercropping systems is too simple, and the bandwidth ratio of corn and halophytes is not adapted to the degree of salinity, making it impossible to achieve a balance between salt absorption and resource utilization; the coordination between irrigation and drainage and improvement measures is poor, and traditional flood irrigation not only has a water resource utilization rate of less than 30%, but also lacks salt drainage channels, and leached salt is prone to rise back with groundwater infiltration, etc.

[0004] Therefore, developing a synergistic regulation method that adapts to different salinity levels, balances water conservation and salt reduction, and achieves increased crop yields has become a problem that the industry needs to solve. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and propose a water-saving and salt-reducing synergistic regulation method for intercropping salt-tolerant maize with halophytes.

[0006] The specific technical solution is as follows: A water-saving and salt-reducing synergistic regulation method for intercropping salt-tolerant corn with halophytes, comprising the following steps:

[0007] Step 1: Grading and pretreatment of saline-alkali land. Measure the total salt content and pH value of the topsoil layer (0-20cm). Divide the land into moderate and severe saline-alkali areas. For moderate to severe saline-alkali land, drill holes with a diameter of 25cm and a depth of 100cm at a density of 4m×4m in the severe areas. Fill the 30-60cm layer of the holes with decomposed corn stalks and the 60-100cm layer with quartz sand.

[0008] Step 2: Construct a gradient intercropping system, uniformly adopting a layout pattern of alternating 2 rows of corn strips and halophyte strips. In moderately saturated areas, the combination of corn strip and halophyte strip width is 80cm for corn strip and 40cm for halophyte strip. In severely saturated areas, the combination of corn strip width 80cm for corn strip and 60cm for halophyte strip or corn strip width 80cm for halophyte strip can be selected. The corn strip consists of 2 rows of salt-tolerant corn, and the halophyte strip consists of a mixed planting of Suaeda salsa and Suaeda salsa.

[0009] Step 3: Dynamic irrigation and drainage and water and fertilizer regulation. A composite irrigation and drainage system consisting of drip irrigation tape and underground pipes is laid. Based on the underground pipe layout, a sand-mixing and alkali-suppressing operation is added. The sand content is 15%-20% of the topsoil mass. After mixing, the soil is tilled to a depth of 20cm and thoroughly mixed. The underground pipes are buried 80cm deep, spaced 15m apart, and wrapped with non-woven fabric and a quartz sand filter layer. The drip irrigation tapes are arranged along the crop rows at a spacing of 40cm and a flow rate of 2L / h. Dynamic irrigation is applied according to the soil matrix potential of corn seedlings (-20kPa to -15kPa) and during the jointing stage (-15kPa to -10kPa). For halophytes, leaching is performed every 15 or 20 days from June to August, with a single irrigation volume of 30m³. 3 / mu, after leaching, the salt is discharged through underground pipes;

[0010] Topsoil depth: 0-20cm;

[0011] Step 4: Rhizosphere improvement. Apply 5-8g / hole of compound improver to corn planting holes and 20-24kg / mu of compound improver to halophyte planting furrows. The compound improver is made of 2-3mm particles, which is prepared by mixing modified biochar and salt-tolerant bacteria suspension at a mass ratio of 10:2-3 and then drying.

[0012] As a further technical solution, the regional division criteria in step 1 are as follows: moderate total salinity 8g / kg-15g / kg; heavy total salinity >15g / kg, pH value >8.0.

[0013] As a further technical solution, in step 2, a compact plant type of salt-tolerant corn is selected, with a row spacing of 40cm, which is suitable for the layout of two rows of corn within an 80cm corn strip, with a plant spacing of 20cm, and a seedling density of 5500 plants per mu.

[0014] As a further technical solution, in step 2, *Suaeda salsa* and *Salvia splendens* are mixed and sown at a mass ratio of 2-3:1; the row spacing for mixed sowing is 30cm, matching the width specifications of a 40cm / 60cm / 80cm halophyte strip, and the sowing rate is 8g / m². 2 The biomass (fresh weight) of mixed sowing of Suaeda salsa and Salicornia salsa on one mu of land is about 4000 kg, and the dry weight is 25% of the fresh weight, which is about 1000 kg. The actual biomass is calculated according to the mixed sowing ratio of Suaeda salsa and Salicornia salsa.

[0015] As a further technical solution, step 3 adopts soil testing and formula fertilization, reducing the amount of base fertilizer by 20% compared to traditional fertilization, and applying topdressing fertilizer in 3 times with water through drip irrigation system, with each topdressing amount being 1 / 3 of the total topdressing amount.

[0016] As a further technical solution, the preparation steps of the modified biochar with composite modifier are as follows: using corn stalks as raw material, anaerobic carbonizing at 500-550℃ for 2 hours, then pulverizing to 80 mesh, adding citric acid solution at a solid-liquid ratio of 1:10-12, stirring at 60℃ for 4 hours, filtering and washing with water until neutral, adding 8wt%-10wt% humic acid solution and 0.5wt%-0.7wt% nano-montmorillonite, reacting at 50℃ for 2 hours, and drying at 105℃.

[0017] As a further technical solution, the citric acid solution has a mass fraction of 5.5%; the humic acid solution has a mass fraction of 5.8%.

[0018] As a further technical solution, the preparation steps of the salt-tolerant bacterial suspension are as follows: Take Bacillus subtilis strain, inoculate it into LB medium containing 3wt% NaCl, culture at 30℃ with shaking for 48 hours, collect the bacterial cells by centrifugation, and resuspend it with a protectant containing trehalose and xanthan gum to prepare a suspension with a concentration of 1×10⁻⁶. 9 CFU / mL bacterial suspension.

[0019] As a further technical solution, the protective agent is made by mixing 10g trehalose, 2g xanthan gum and 100mL deionized water.

[0020] As a further technical solution, 2wt% sodium carboxymethyl cellulose is added as a binder during the assembly of the composite modifier, and the mixture is vacuum dried and molded at 35°C.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention classifies saline-alkali land based on the total salt content and pH value of the topsoil layer (0-20cm), rather than the original 0-60cm depth. This better reflects the actual salt damage range of the topsoil layer and provides a precise basis for subsequent measures. For severely affected areas, holes with a diameter of 25cm and a depth of 100cm are drilled at a density of 4m×4m. The 30-60cm layer is filled with decomposed corn stalks, and the 60-100cm layer is filled with quartz sand. The organic acids produced by the decomposed stalks can initially neutralize the soil alkalinity, while the quartz sand constructs deep water-conducting channels, improving soil permeability and effectively solving the problem of salt retention and poor drainage in severely saline-alkali land. Moderately affected areas only require deep tillage to 20cm and land leveling, without drilling, avoiding resource misallocation caused by a "one-size-fits-all" approach. Mildly affected areas are not included in the treatment, focusing on the core needs of moderate to severe areas.

[0023] This invention employs a uniform layout of alternating 2-row corn strips (80cm) and halophyte strips: in moderately saline areas, the strip ratio is 80cm (corn):40cm (halophiles); in severely saline areas, it is 80cm:60cm or 80cm:80cm. The halophytes are a mixture of Suaeda salsa and Salicyla serrata in a specific mass ratio. This layout creates a suitable salt absorption gradient between salt-tolerant corn and halophytes: the halophytes reduce the salt concentration in the top 0-10cm soil layer through root salt secretion, creating a localized low-salt microenvironment for corn, resulting in a more than 25% increase in the fresh weight of individual corn roots compared to traditional planting methods; simultaneously, the halophyte strips have a 30cm row spacing and a salt content of 8g / m³. 2 The seeding rate should be set in a way that balances biomass and salt control, and avoids competition for resources between halophytes and maize.

[0024] Precision irrigation to prevent backflow: Drip irrigation tapes are arranged at 40cm intervals with a flow rate of 2L / h. Combined with dynamic adjustment of soil matrix potential (-20kPa to -15kPa during the corn seedling stage and -15kPa to -10kPa during the jointing stage), precise water supply is achieved, avoiding the problem of "salt flowing away with the water but backflow and salt accumulation" caused by traditional flood irrigation; halophytes are irrigated with a 30m² leaching solution every 15-20 days from June to August. 3 / acre, simultaneously coordinating with underground pipe salt discharge to form a leaching-discharge linkage.

[0025] Sand mixing and underground pipe anti-clogging efficiency improvement: By mixing sand to suppress alkali, soil porosity can be improved and water infiltration efficiency can be enhanced; the underground pipes are buried at a depth of 80cm and a spacing of 15m, and are wrapped with non-woven fabric and quartz sand filter layer, which can effectively intercept soil particles to prevent clogging, and the salt removal efficiency is improved compared with the design without filter layer.

[0026] Enhanced Adsorption and Salt Tolerance: Modified biochar uses corn stalks as raw material, undergoes anaerobic carbonization at 500-550℃, modification with citric acid solution, and the addition of humic acid and nano-montmorillonite, thus improving both adsorption and salt tolerance. + The adsorption capacity was further reduced by modifying the biochar with citric acid to counteract its weak alkalinity and introduce acidic groups. The salt-tolerant bacteria suspension was Bacillus subtilis, which can secrete extracellular polysaccharides to reduce the permeability of corn root cell membranes and increase the salt tolerance threshold of corn.

[0027] Long-lasting and stable, preventing runoff: Adding 2wt% sodium carboxymethyl cellulose as a binder and vacuum drying at 35℃ ensures that the amendment particles remain stable in the soil for more than 6 months, preventing runoff during the rainy season.

[0028] Intercropping systems enhance farmland biodiversity and avoid ecological monoculture caused by monoculture; the technical solutions expand arable land resources in moderately to severely saline-alkali areas, while also conforming to the direction of green governance, providing replicable solutions for saline-alkali regions. Attached Figure Description

[0029] Figure 1This is a flowchart of the water-saving and salt-reducing synergistic regulation method for intercropping salt-tolerant maize and halophytes according to the present invention.

[0030] Figure 2 This is a schematic diagram illustrating the planting of salt-tolerant corn belts and halophyte belts according to the present invention. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] This invention provides a water-saving and salt-reducing synergistic regulation method for intercropping salt-tolerant maize with halophytes, comprising the following steps:

[0033] Step 1: Grading and pretreatment of saline-alkali land. Measure the total salt content and pH value of the topsoil layer (0-20cm). Divide the land into moderate and severe saline-alkali areas. Carry out pretreatment for moderate and severe saline-alkali land. In the severe areas, drill holes at a specific density and fill the holes with corresponding materials at different depths.

[0034] Step 2: Construct a gradient intercropping system, uniformly adopting a 2-row alternating layout of maize strip and halophyte strip, with differentiated halophyte strip widths for moderate and severe areas, and clearly defining the crop configuration of maize strip and halophyte strip;

[0035] Step 3: Dynamic irrigation and drainage and water and fertilizer regulation, laying a composite irrigation and drainage system, adding sand mixing and alkali suppression operation on the basis of underground pipe laying, setting drip irrigation and rinsing irrigation parameters to achieve dynamic irrigation and drainage and water and fertilizer synergy;

[0036] Step 4: Rhizosphere improvement. Apply compound amendment to corn planting holes and halophyte planting furrows respectively, and clarify the specifications and raw material ratio of the compound amendment.

[0037] This invention achieves the dual goals of water conservation and salt reduction, and increased crop yield in moderately to severely saline-alkali land through the synergistic effects of graded pretreatment of saline-alkali land, gradient intercropping layout, dynamic irrigation and drainage regulation, and rhizosphere improvement. This method is highly targeted and adaptable to varying degrees of moderately to severely saline-alkali land, exhibiting significant water-saving effects, high soil desalination rates, and increased crop yields. It addresses the problems of water waste, incomplete desalination, and poor crop growth in traditional saline-alkali land management.

[0038] Each step is explained in detail:

[0039] The grading and pretreatment of saline-alkali land in step 1 of this invention defines the grading standard as follows: moderate salinity (8g / kg-15g / kg total salinity) and severe salinity (>15g / kg total salinity). The soil layer to be measured is the topsoil layer (0-20cm). For both moderate and severe saline-alkali land, basic deep tillage pretreatment is required. In moderately saline-alkali areas, the land is tilled to a depth of 20cm and leveled. In severely saline-alkali areas, in addition to tilling to a depth of 20cm, holes are drilled at a density of 4m×4m, with a hole diameter of 25cm and a hole depth of 100cm. The first 30-60cm layer inside the hole is filled with decomposed corn stalks, and the next 60-100cm layer is filled with quartz sand.

[0040] In step 2 of constructing the gradient intercropping system, the corn strip consists of two rows of salt-tolerant corn. Compact varieties are preferred, with a row spacing of 40cm (suitable for an 80cm corn strip width) and a plant spacing of 20cm, maintaining 5500 plants per mu (approximately 0.067 hectares). The halophyte strip consists of a mixed planting of *Suaeda salsa* and *Saussurea involucrata*, sown at a ratio of 2-3:1 by weight, with a row spacing of 30cm and a seeding rate of 8g / m². 2 In moderately affected areas, the corn belt width is 80cm and the halophyte belt width is 40cm. In severely affected areas, an 80cm corn belt width can be combined with a 60cm halophyte belt width, or an 80cm corn belt width can be combined with an 80cm halophyte belt width.

[0041] In step 3 of the dynamic irrigation and drainage and water and fertilizer regulation, the buried depth of the subsurface pipes in the composite irrigation and drainage system is preferably 60cm, the spacing is preferably 25m, and the outer layer is wrapped with non-woven fabric and quartz sand filter layer. After the subsurface pipes are laid, sand mixing and alkali suppression operation needs to be carried out. The amount of sand mixed is 15%-20% of the soil mass of the 0-20cm topsoil layer. After mixing, the soil is tilled to a depth of 20cm and mixed evenly. The drip irrigation tape is arranged along the crop rows, with a spacing of preferably 40cm and a flow rate of preferably 2L / h. The irrigation parameters are preferably -20kPa to -15kPa soil matrix potential during the corn seedling stage and -15kPa to -10kPa dynamic irrigation during the jointing stage. For halophytes, leaching irrigation is carried out every 15 or 20 days from June to August, and the single irrigation volume is preferably 30m³. 3 / acre, after leaching, salt is discharged through underground pipes. Water and fertilizer management preferably adopts soil testing and formula fertilization. The amount of base fertilizer applied is reduced by 20% compared with traditional fertilization. Topdressing is applied in 3 times with water through drip irrigation system, and the amount of topdressing each time is 1 / 3 of the total amount of topdressing.

[0042] In step 4 of the rhizosphere improvement process, the composite amendment is preferably made of granules with a particle size of 2-3 mm, prepared by mixing modified biochar and salt-tolerant bacteria suspension at a mass ratio of 10:2-3 and then drying. The preferred application dosage is 5-8 g / hole for corn planting and 20-24 kg / acre for halophyte planting furrows.

[0043] The preferred steps for preparing modified biochar with composite amendment are as follows: using corn stalks as raw material, anaerobic carbonizing at 500-550℃ for 2 hours, then pulverizing to 80 mesh, adding 5.5% citric acid solution at a solid-liquid ratio of 1:10-12, stirring at 60℃ for 4 hours, filtering and washing with water until neutral, then adding 8wt%-10wt% humic acid solution (preferably 5.8% wt%) and 0.5wt%-0.7wt% nano-montmorillonite, reacting at 50℃ for 2 hours, and drying at 105℃.

[0044] The preferred steps for preparing the salt-tolerant bacterial suspension are as follows: Take a commercially available Bacillus subtilis strain, inoculate it into LB medium containing 3 wt% NaCl, incubate at 30°C with shaking for 48 h, collect the bacterial cells by centrifugation, resuspend it with a protectant, and prepare a suspension with a concentration of 1×10⁻⁶. 9 A bacterial suspension with CFU / mL. The preservative is preferably prepared by mixing 10g trehalose, 2g xanthan gum, and 100mL deionized water.

[0045] When assembling the composite modifier, it is preferable to add 2wt% sodium carboxymethyl cellulose as a binder and then vacuum dry and mold it at 35°C.

[0046] To further illustrate the present invention, the following detailed description is provided through the examples, comparative examples, and experiments. In the following examples and comparative examples of the present invention: the salt-tolerant corn variety used is "Denghai 618" (compact plant type); the seeds of *Suaeda salsa* and *Suaeda salsa* are both commercially available conventional varieties; the modified biochar of the compound improver is prepared according to the above-mentioned preferred steps; the salt-tolerant bacteria suspension is prepared according to the above-mentioned preferred steps; the decomposed corn stalks, quartz sand, citric acid, humic acid, nano-montmorillonite, sodium carboxymethyl cellulose, trehalose, xanthan gum, etc. are all commercially available conventional products.

[0047] Example 1:

[0048] Saline-alkali land classification and pretreatment: If the total salt content of the topsoil (0-20cm) is <15.0g / kg and the pH value is >8.0, it is classified as a moderately saline-alkali area. The soil is then deeply tilled to a depth of 20cm and the land is leveled.

[0049] Gradient intercropping system construction: A two-row corn strip-halophyte strip alternating layout was adopted, with the corn strip width 80cm and the halophyte strip width 40cm. Two rows of salt-tolerant corn were planted in the corn strip, with a row spacing of 40cm and a plant spacing of 20cm, maintaining 5500 plants per mu (approximately 0.067 hectares). The halophyte strip was planted with a mixed sowing of *Suaeda salsa* and *Saussurea involucrata* at a 2:1 mass ratio, with a row spacing of 30cm and a seeding rate of 8g / m². 2 .

[0050] Dynamic irrigation and drainage with water and fertilizer regulation: A composite irrigation and drainage system consisting of drip irrigation tape and underground pipes is installed. The underground pipes are buried at a depth of 80cm and spaced 15m apart, covered with a non-woven fabric and quartz sand filter layer. The sand content is 15% of the topsoil mass, and after mixing, it is tilled to a depth of 20cm. The drip irrigation tapes are laid along the crop rows at a spacing of 40cm, with a flow rate of 2L / h. During the corn seedling stage, dynamic irrigation is applied at a soil matrix potential of -19kPa, and during the jointing stage, dynamic irrigation is applied at a soil matrix potential of -13kPa. Halophytes are irrigated every 15 days from June to August, with a single irrigation volume of 30m³. 3 / acre, salt is discharged through underground pipes after leaching. Soil testing and formula fertilization are adopted, and the amount of base fertilizer applied is reduced by 20% compared with traditional fertilization. Topdressing is applied in 3 times with water through drip irrigation system, and the amount of topdressing each time is 1 / 3 of the total amount of topdressing.

[0051] Rhizosphere improvement: Apply 7g / hole of compound conditioner to corn planting holes and 23kg / acre of compound conditioner to halophyte planting furrows. The compound conditioner consists of 2-3mm granules, made by mixing modified biochar and salt-tolerant bacteria suspension at a mass ratio of 10:2.8, adding 2wt% sodium carboxymethyl cellulose as a binder, and vacuum drying at 35℃.

[0052] Example 2:

[0053] Saline-alkali land classification and pretreatment: Areas with a total salt content >15g / kg and pH value >8.0 in the topsoil layer (0-20cm) were classified as severely saline-alkali areas. Holes with a diameter of 25cm and a depth of 100cm were drilled at a density of 4m×4m. The first 30-60cm layer was filled with decomposed corn stalks, and the next 60-100cm layer was filled with quartz sand. The soil was then deeply tilled to a depth of 20cm and the land leveled.

[0054] Gradient intercropping system construction: A two-row corn strip-halophyte strip alternating layout was adopted, with the corn strip width 80cm and the halophyte strip width 60cm. Two rows of salt-tolerant corn were planted in the corn strip, with a row spacing of 40cm and a plant spacing of 20cm, maintaining 5500 plants per mu (approximately 0.067 hectares). The halophyte strip was planted with a mixed sowing of *Suaeda salsa* and *Saussurea involucrata* at a 3:1 mass ratio, with a row spacing of 30cm and a seeding rate of 8g / m². 2 .

[0055] Dynamic irrigation and drainage with water and fertilizer regulation: A composite irrigation and drainage system consisting of drip irrigation tape and underground pipes is installed. The underground pipes are buried at a depth of 80cm and spaced 15m apart, covered with non-woven fabric and a quartz sand filter layer. The sand content is 18% of the topsoil mass, and after mixing, it is tilled to a depth of 20cm. The drip irrigation tapes are arranged along the crop rows at a spacing of 40cm and a flow rate of 2L / h. During the corn seedling stage, dynamic irrigation is applied at a soil matrix potential of -20kPa, and during the jointing stage, dynamic irrigation is applied at a soil matrix potential of -15kPa. Halophytes are irrigated every 20 days from June to August, with a single irrigation volume of 30m³. 3 / acre, salt is discharged through underground pipes after leaching. Soil testing and formula fertilization are adopted, and the amount of base fertilizer applied is reduced by 20% compared with traditional fertilization. Topdressing is applied in 3 times with water through drip irrigation system, and the amount of topdressing each time is 1 / 3 of the total amount of topdressing.

[0056] Rhizosphere improvement: Apply 8g / hole of compound conditioner to corn planting holes and 24kg / acre of compound conditioner to halophyte planting furrows. The compound conditioner consists of 2-3mm granules, made by mixing modified biochar and salt-tolerant bacteria suspension at a mass ratio of 10:3, adding 2wt% sodium carboxymethyl cellulose as a binder, and vacuum drying at 35℃.

[0057] Example 3:

[0058] Saline-alkali land classification and pretreatment: Areas with a total salt content greater than 15 g / kg and a pH value greater than 8.0 in the topsoil layer (0-20 cm) are classified as severely saline-alkali areas. Holes with a diameter of 25 cm and a depth of 100 cm are drilled at a density of 4 m × 4 m. The first 30-60 cm layer is filled with decomposed corn stalks, and the next 60-100 cm layer is filled with quartz sand. The soil is then deeply tilled to a depth of 20 cm and the land is leveled.

[0059] Gradient intercropping system construction: A two-row corn strip-halophyte strip alternating layout was adopted, with both corn and halophyte strips being 80cm wide. Two rows of salt-tolerant corn were planted in the corn strips, with a row spacing of 40cm and a plant spacing of 20cm, maintaining 5500 plants per mu (approximately 0.067 hectares). The halophyte strips were planted with a mixture of *Suaeda salsa* and *Saussurea involucrata* at a mass ratio of 2.5:1, with a row spacing of 30cm and a seeding rate of 8g / m². 2 .

[0060] Dynamic irrigation and drainage with water and fertilizer regulation: A composite irrigation and drainage system consisting of drip irrigation tape and underground pipes is laid. The underground pipes are buried at a depth of 80cm and spaced 15m apart, covered with a non-woven fabric and quartz sand filter layer. The sand content is 20% of the topsoil mass, and after mixing, it is tilled to a depth of 20cm to ensure even distribution. The drip irrigation tapes are laid along the crop rows at a spacing of 40cm and a flow rate of 2L / h. During the corn seedling stage, dynamic irrigation is applied at a soil matrix potential of -18kPa, and during the jointing stage, dynamic irrigation is applied at a soil matrix potential of -14kPa. For halophytes, leaching is performed every 15 days from June to August, with a single irrigation volume of 30m³. 3 / acre, salt is discharged through underground pipes after leaching. Soil testing and formula fertilization are adopted, and the amount of base fertilizer applied is reduced by 20% compared with traditional fertilization. Topdressing is applied in 3 times with water through drip irrigation system, and the amount of topdressing each time is 1 / 3 of the total amount of topdressing.

[0061] Rhizosphere improvement: Apply 7g / hole of compound conditioner to corn planting holes and 22kg / mu of compound conditioner to halophyte planting furrows. The compound conditioner is made of 2-3mm particles, which are produced by mixing modified biochar and salt-tolerant bacteria suspension at a mass ratio of 10:2.5, adding 2wt% sodium carboxymethyl cellulose as a binder, and vacuum drying at 35℃.

[0062] Comparative Example 1:

[0063] The treatment method provided in Example 1 is adopted, except that: step 4, rhizosphere improvement, is not carried out, that is, no compound amendment is applied to the corn planting hole and the halophyte planting furrow. The remaining steps and parameters are completely consistent with those in Example 1.

[0064] Comparative Example 2:

[0065] The treatment method provided in Example 1 is adopted, except that: step 3 does not involve sand mixing and alkali suppression, and the dynamic irrigation and drainage and water and fertilizer regulation are changed to the traditional flood irrigation method. The drip irrigation tape and underground pipe combined irrigation and drainage system are not laid. Corn is irrigated in the traditional way. Halophytes are not specially irrigated. Fertilization is carried out in the traditional one-time fertilization method. The amount of base fertilizer is the conventional amount. No topdressing is carried out. The remaining steps and parameters are completely consistent with Example 1.

[0066] Experiment 1: Soil desalination effect test;

[0067] Experimental materials and site: The soil at the experimental site was measured to be sulfate-type silty clay, with the following basic physicochemical properties: pH of the 0-100cm soil layer was 8.18-8.38, and the bulk density of the 0-20cm topsoil layer was 1.72 g / cm³. 3 The soil has a permeability coefficient of 0.00624 cm / h, sulfate accounts for 90.05%-92.52% of the total salt, soil organic matter is about 12 g / kg, available nitrogen is 42.01-46.84 mg / kg, and available phosphorus is 4.93-5.90 mg / kg.

[0068] Processing Design: Examples 1-3 (method of the present invention) and Comparative Examples 1-2 (control method) were set up, with 3 replicate cells for each treatment, and each cell area was 30m². 2 A 1m isolation row is set between the small units.

[0069] Measurement indicators and methods: Soil samples were collected from the 0-10cm and 10-20cm layers of each plot before sowing (before the experiment) and after corn harvest (after the experiment). Three replicates were taken from each soil layer and mixed to form a representative sample. The total salt content of the soil was determined by the gravimetric method: After air-drying and passing the soil samples through a 2mm sieve, they were extracted by shaking at a soil-to-water ratio of 1:5 for 30 minutes. After filtration, the supernatant was collected, evaporated and dried at a constant temperature of 80℃ until constant weight, and the salt mass was weighed. The desalination rate of the soil layer and the overall desalination rate (salt leaching rate) were calculated.

[0070] Key operating parameters: Buried depth of underground pipes 80cm, spacing 15m (outer layer of non-woven fabric and quartz sand filter), sand content 20%-25% of the topsoil mass (particle size 0.5-1mm); Experimental results:

[0071] Table 1 Soil desalination effect

[0072]

[0073] As shown in Table 1, the method of the present invention (Examples 1-3) achieved efficient desalination in sulfate-type moderately to severely saline-alkali land:

[0074] In moderately saline-alkali land (Example 1), the desalination rate of the 0-10cm topsoil reached 48.6%, the desalination rate of the 10-20cm soil layer was 44.4%, and the overall desalination rate was 47.0%, with the surface desalination effect being better than that of the deeper layers.

[0075] The overall desalination rate of severely saline-alkali land (Examples 2-3) remained stable at 34.0%-37.0%, although the desalination rate was lower than that of moderately saline-alkali land due to the high initial salinity and low sulfate solubility.

[0076] As can be seen from the comparison, the present invention effectively solves the problems of poor drainage and sulfate retention in silty clay through the synergistic effect of "deep burial of underground pipes, sand mixing and improvement, and rhizosphere conditioning". The desalination effect is 1.9-2.0 times better than traditional flood irrigation (Comparative Example 2) and better than the treatment without amendment (Comparative Example 1), which verifies the pertinence and effectiveness of the method.

[0077] Experiment 2: Maize yield and halophyte biomass;

[0078] Experimental materials: The salt-tolerant maize variety was "Denghai 618" (compact plant type), and the seeds of Suaeda salsa and Suaeda salsa were commercially available conventional varieties.

[0079] Measurement indicators and methods:

[0080] Corn yield: At harvest, remove the two protective plants at the edge of the row and the first row of the plot, collect the ears of the middle plants, air dry and thresh them, and calculate the yield per mu based on the standard moisture content of 14%. At the same time, measure the number of kernels per ear and the weight of 1000 kernels (10 ears of corn are randomly selected from each plot for measurement).

[0081] Halophyte biomass: Harvest the above-ground parts of halophytes at the end of the growth period (September), measure the fresh weight of Suaeda salsa and Suaeda salsa, calculate the dry weight based on the measured dry-to-fresh ratio of 25%, and calculate the biomass per mu.

[0082] Experimental results:

[0083] Table 2 Crop Yield and Biomass

[0084] Processing group Number of kernels per ear of corn 1000-kernel weight of corn (g) Corn yield per mu (kg) Biomass of Suaeda salsa in saline-alkali soil (kg) Biomass of *Salmonella salina* per mu (kg) Total biomass of halophytes per mu (kg) Example 1 420 290 360 562.5 187.5 750.6 Example 2 380 275 290 472.5 157.5 630.2 Example 3 390 280 300 495.0 165.0 660.1 Comparative Example 1 330 260 270 400.0 133.3 533.3 Comparative Example 2 290 245 210 352.5 117.5 470.5

[0085] Corn growth performance: The number of kernels per ear, thousand-kernel weight, and yield per mu of corn in Examples 1-3 were significantly better than those in the comparative examples. Among them, the corn yield per mu in moderately saline-alkali land (Example 1) reached 360 kg, which was 71.4% higher than that of traditional flood irrigation (Comparative Example 2) and 33.3% higher than that of the treatment without soil conditioner (Comparative Example 1); the yield per mu in severely saline-alkali land (Examples 2-3) was 290-300 kg, which was 38.1%-42.9% higher than that of Comparative Example 2, which verified the adaptability of the present invention to high-salt and low-nutrient soils.

[0086] Halophyte biomass: The total biomass of halophytes in Examples 1-3 reached 630-750 kg / mu, an increase of 34.0%-59.6% compared to Comparative Example 2 (470 kg). This fully demonstrated their advantage in sulfate absorption, reducing soil salinity and generating additional biological output.

[0087] Experiment 3: Water use efficiency;

[0088] Measurement indicators and methods:

[0089] Total irrigation volume: The total amount of drip irrigation and leaching irrigation for halophytes throughout the entire growth period is accurately measured using water meters;

[0090] Rainfall during the reproductive period: monitored by automatic weather stations at the experimental site;

[0091] Soil water consumption: The soil water consumption was calculated by measuring the change in soil moisture content in the 0-20cm layer before sowing and after harvest using the oven drying method.

[0092] Water use efficiency: Calculated by the formula: Water use efficiency = (irrigation amount + soil water consumption + rainfall) / corn yield per mu (the lower the value, the more efficient the water use).

[0093] Experimental results:

[0094] Table 3 Water use efficiency

[0095] Processing group Total water applied (m 3 acre) Rainfall during the growing season (m 3 / acre) Soil water consumption (m 3 acre)]]> Corn yield per mu (kg) <![CDATA[Water use efficiency (m 3 / kg)]]> Example 1 (Moderate) 290 80 60 360 1.14 Example 2 (Severe) 330 80 70 290 1.48 Example 3 (Severe) 310 80 65 300 1.39 Comparative Example 1 (without modifier) 290 80 60 270 1.47 Comparative Example 2 (Traditional flood irrigation) 480 80 75 210 2.15

[0096] Water use efficiency: The water use efficiency of Examples 1-3 is 1.14-1.48m. 3 / kg, significantly lower than the comparative example, indicating that the synergistic measures of "dynamic precision irrigation and underground pipe salt drainage" of the present invention effectively improve water use efficiency.

[0097] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not describe all details exhaustively, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification.

Claims

1. A method for water-saving and salt-reducing synergistic regulation of intercropping salt-tolerant maize with halophytes, characterized in that, Includes the following steps: Step 1: Grading and pretreatment of saline-alkali land. Measure the total salt content and pH value of the topsoil layer (0-20cm). Divide the land into moderate and severe saline-alkali areas. For moderate to severe saline-alkali land, drill holes with a diameter of 25cm and a depth of 100cm at a density of 4m×4m in the severe areas. Fill the 30-60cm layer of the holes with decomposed corn stalks and the 60-100cm layer with quartz sand. Step 2: Construct a gradient intercropping system, uniformly adopting a layout pattern of alternating 2 rows of corn strips and halophyte strips. In moderately saturated areas, the combination of corn strip and halophyte strip width is 80cm for corn strip and 40cm for halophyte strip. In severely saturated areas, the combination of corn strip width 80cm for corn strip and 60cm for halophyte strip or corn strip width 80cm for halophyte strip can be selected. The corn strip consists of 2 rows of salt-tolerant corn, and the halophyte strip consists of a mixed planting of Suaeda salsa and Suaeda salsa. Step 3: Dynamic irrigation and drainage and water and fertilizer regulation. A composite irrigation and drainage system consisting of drip irrigation tape and underground pipes is laid. Based on the underground pipe layout, a sand-mixing and alkali-suppressing operation is added. The sand content is 15%-20% of the topsoil mass. After mixing, the soil is tilled to a depth of 20cm and thoroughly mixed. The underground pipes are buried 80cm deep, spaced 15m apart, and wrapped with non-woven fabric and a quartz sand filter layer. The drip irrigation tapes are arranged along the crop rows at a spacing of 40cm and a flow rate of 2L / h. Dynamic irrigation is applied according to the soil matrix potential of corn seedlings (-20kPa to -15kPa) and during the jointing stage (-15kPa to -10kPa). For halophytes, leaching is performed every 15 or 20 days from June to August, with a single irrigation volume of 30m³. 3 / mu, after leaching, the salt is discharged through underground pipes; Topsoil depth: 0-20cm; Step 4: Rhizosphere improvement. Apply 5-8g / hole of compound improver to corn planting holes and 20-24kg / mu of compound improver to halophyte planting furrows. The compound improver is made of 2-3mm particles, which is prepared by mixing modified biochar and salt-tolerant bacteria suspension at a mass ratio of 10:2-3 and then drying.

2. The method according to claim 1, characterized in that, The criteria for dividing the region in step 1 are: moderate total salt content 8g / kg-15g / kg; heavy total salt content >15g / kg, pH value >8.

0.

3. The method according to claim 1, characterized in that, In step 2, a compact plant type of salt-tolerant corn is selected, with a row spacing of 40cm, suitable for a layout of 2 rows of corn within an 80cm corn strip, a plant spacing of 20cm, and a seedling density of 5500 plants per mu.

4. The method according to claim 1, characterized in that, In step 2, *Suaeda salsa* and *Salvia splendens* are mixed and sown at a mass ratio of 2-3:1; the row spacing for mixed sowing is 30cm, matching the width specifications of a 40cm / 60cm / 80cm halophyte strip, and the sowing rate is 8g / m². 2 .

5. The method according to claim 1, characterized in that, In step 3, soil testing and fertilizer formulation are adopted. The amount of base fertilizer applied is reduced by 20% compared with the traditional amount of fertilizer applied. The topdressing is applied in 3 times with water through the drip irrigation system, and the amount of topdressing each time is 1 / 3 of the total amount of topdressing.

6. The method according to claim 1, characterized in that, The steps for preparing modified biochar with composite amendment are as follows: using corn stalks as raw material, anaerobic carbonization at 500-550℃ for 2 hours, then pulverizing to 80 mesh, adding citric acid solution at a solid-liquid ratio of 1:10-12, stirring at 60℃ for 4 hours, filtering and washing with water until neutral, adding 8wt%-10wt% humic acid solution and 0.5wt%-0.7wt% nano-montmorillonite, reacting at 50℃ for 2 hours, and drying at 105℃.

7. The method according to claim 6, characterized in that, The citric acid solution had a mass fraction of 5.5%; the humic acid solution had a mass fraction of 5.8%.

8. The method according to claim 1, characterized in that, The preparation steps for the halophilic bacterial suspension are as follows: Take Bacillus subtilis strain, inoculate into LB medium containing 3wt% NaCl, culture at 30℃ with shaking for 48 h, collect the bacterial cells by centrifugation, and resuspend in a protectant containing trehalose and xanthan gum to prepare a suspension with a concentration of 1×10⁻⁶. 9 CFU / mL bacterial suspension.

9. The method according to claim 8, characterized in that, The protective agent is made by mixing 10g trehalose, 2g xanthan gum and 100mL deionized water.

10. The method according to claim 1, characterized in that, During the assembly of the composite modifier, 2 wt% sodium carboxymethyl cellulose was added as a binder, and the mixture was vacuum dried and molded at 35°C.

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