A high-quality forage grass production method based on saline-alkali land ecological restoration

Abstract

The application provides a high-quality forage grass production method based on saline-alkali land ecological restoration, and belongs to the technical field of saline-alkali land ecological restoration. The method of the application directly reduces the surface soil salt source by physical desalination at the spring salt return peak period, breaks the hardening barrier, uses the salt-tolerant pioneer plant Suaeda to actively absorb salt and reduce pH, and creates a low-salt microenvironment for the growth of subsequent crops, and introduces the deep-rooted high-quality forage grass switchgrass to continuously improve the soil while producing high-protein forage (switchgrass). The method aims to overcome the technical problems of the prior art, such as repeated treatment, high cost and no economic output, and realizes a new mode of sustainable utilization of saline-alkali land, that is, promoting treatment by use and producing while restoring.

Description

Technical Field

[0001] This invention belongs to the field of saline-alkali land ecological restoration technology, and in particular relates to a method for producing high-quality forage based on saline-alkali land ecological restoration. Background Technology

[0002] Soil salinization is a key obstacle to sustainable agricultural development and ecological security worldwide. In the "Three Norths" region (Northeast, North China, and Northwest China), the area of ​​saline-alkali land reaches as high as 29.8498 million hectares. 2 This accounts for 82.2% of the total area of ​​saline-alkali land in China (Ma Kai et al., 2023). Among them, the problem is particularly severe in the Northeast soda saline-alkali area, with the Songnen Plain as its core. The soil in this area is mainly soda saline-alkali soil, characterized by extremely high pH value (often >10.0), highly dispersed soil colloids, and extremely poor permeability. It is the most difficult to improve among all types of saline-alkali soil.

[0003] Currently, the main technical approaches used both domestically and internationally for the treatment of severely soda-saline-alkali soils are as follows, but all of them have significant limitations: First, engineering and physical improvement methods are costly and lack sustainability. While soil replacement can change the soil matrix in the short term, the engineering cost is extremely high, and large-scale soil removal causes serious topsoil disturbance and secondary ecological damage, making it unsuitable for widespread application in the vast, severely saline-alkali areas of the Songnen Plain. Traditional large-scale salt washing requires a large amount of freshwater resources, which are scarce in this region. Furthermore, with strong evaporation in spring after salt washing, deep salts easily accumulate on the surface again, leading to a vicious cycle of salt washing and salt return, resulting in inconsistent treatment effects.

[0004] Secondly, engineering-based salt drainage and chemical amendment measures face environmental risks and applicability bottlenecks. While engineering measures such as underground pipe drainage can lower the local groundwater level, the lack of natural drainage areas in the saline-alkali regions of Northeast China means that the discharged high-salt water accumulates in low-lying areas, forming new salt source accumulation zones, and does not fundamentally eliminate salt damage. Long-term and excessive application of chemical amendments (such as gypsum and aluminum sulfate) can easily lead to soil compaction and calcium-magnesium ion imbalance, and may also introduce heavy metal residues, threatening the quality and safety of subsequent agricultural products.

[0005] Third, biological and microbial remediation methods lack stability. Although exogenous functional microorganisms can theoretically regulate the rhizosphere microenvironment, their colonization rate is generally less than 20% under high salt and alkali stress in the field. They are severely affected by soil pH fluctuations and rapid changes in salinity, making the remediation effect extremely uncontrollable and difficult to form a stable plant-microbe interaction system.

[0006] More importantly, existing saline-alkali land management technologies generally overlook a unique type of seasonal obstacle and long-term economic driving mechanism. In the cold regions of Northeast China, after the freeze-thaw cycle in winter and the intense evapotranspiration in spring, a large amount of salt in the deep soil migrates and accumulates to the surface, forming a dense salt crust. If this salt crust is not actively removed during the peak salt return period before the rainy season (late April to early May), the salt will be re-infiltrated into the deep soil after being washed away by rainwater. This not only greatly increases the difficulty of subsequent management but also directly leads to the death of a large number of seedlings sown in spring due to high salt stress. Current improvement technologies mostly focus on passive salt leaching or in-situ neutralization, lacking proactive intervention strategies targeting this critical phenological window.

[0007] Furthermore, existing governance models are generally trapped in a "only input, no output" dilemma. Traditional improvement methods have long cycles, require large upfront investments, and lack economic returns during the restoration process, resulting in a lack of enthusiasm for participation from local governments and farmers. This makes it difficult for comprehensive management of saline-alkali land to form a long-term, self-sustaining mechanism. The sharp contradiction between ecological restoration and economic benefits has become a key bottleneck restricting the resource utilization of severely saline-alkali land in my country.

[0008] In view of this, the present invention provides a method for producing high-quality forage based on the ecological restoration of saline-alkali land. Summary of the Invention

[0009] To address the problems of existing saline-alkali land restoration technologies neglecting economic output and difficulty in recovering restoration costs, this invention proposes a high-quality forage production method based on saline-alkali land ecological restoration. This invention achieves a sustainable saline-alkali land management model of "restoration and production simultaneously" through physical desalination, pH regulation using Suaeda salsa, and planting switchgrass forage.

[0010] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for producing high-quality forage based on the ecological restoration of saline-alkali land. The method is used to establish switchgrass on severely soda-type saline-alkali land with pH>10.0, and includes the following steps: (1) For severely soda-type saline-alkali patches with pH>10.0, the accumulated salt crust layer on the surface is artificially removed in spring to reduce the salt source in the topsoil. (2) Apply organic fertilizer to the soil after removing the salt crust layer, till and mix it evenly, and then irrigate until the soil is moist. (3) Sowing Suaeda salsa ( Halogeton glomeratus Seeds, sowing rate is 15–30 kg / hm. 2 By utilizing the salt accumulation and pH reduction effects of Suaeda salsa during its growth process, a low-salt microenvironment can be created for the subsequent establishment of switchgrass. (4) After the Suaeda salsa enters its vigorous growth period, transplant Sorghum stenoptera (Salix matsudana) into the gaps between the plants. Panicum virgatum Seedlings, transplanting density is 20,000 to 30,000 plants / hm² 2; (5) Water management should be carried out according to the principle of supplementing water in the dry season and supplementing less water in the rainy season. At the end of the growing season of the year, Suaeda salsa should be pulled out and used for feeding after the willow branch millet turns green the following year.

[0011] Technical principle: This invention constructs a five-step synergistic chain of physical source reduction, organic soil improvement, pioneer alkali reduction, deep-rooted forage grass, and water and salt regulation: Physical removal of salt crust in spring: Taking advantage of the salt accumulation pattern caused by winter freeze-thaw and spring evaporation in soda saline-alkali areas, the salt source is actively removed before the peak of salt return, thus breaking the vicious cycle of salt crust leaching and infiltration, and secondary salt return.

[0012] Rotary tillage with organic fertilizer: The humus in cow manure organic fertilizer can absorb sodium. + It improves the soil aggregate structure, and rotary tillage breaks up the compacted layer, enhancing water infiltration.

[0013] Sowing Suaeda salsa: Utilizing the salt-accumulating properties of Suaeda salsa, salt is absorbed through the root system and removed along with the roots during harvesting, thus actively reducing soil pH and salinity.

[0014] Planting switchgrass: Utilizing the deep root system (improving deep structure) and high light efficiency of C4 (high biomass), switchgrass can be established in succession after the saline-alkali environment is improved, thus achieving forage production.

[0015] Water management and harvesting: Water supplements during the dry season to ensure seedling survival, and water sparingly during the rainy season to utilize natural salt leaching; harvest Suaeda salsa to remove salt, and leave stubble on Sorghum to ensure greening the following year.

[0016] The five steps described above constitute a synergistic technical chain, none of which can be omitted: If the physical desalination in step (1) is omitted, the salt crust will be leached into the deep soil layer after the rainy season in spring, and any subsequent biological improvement measures will not be effective under extremely high salt stress. The switchgrass seedlings will not survive if they are directly exposed to an extreme environment with an electrical conductivity >70 mS / cm and a pH >10.0. If the planting of Suaeda salsa in step (3) is omitted, there is a lack of preconditions for creating a low-salt microenvironment for switchgrass, and the switchgrass will not be able to complete its establishment due to the lack of a sheltered habitat. Therefore, physical desalination and pioneer planting of Suaeda salsa are necessary prerequisites for the successful establishment of switchgrass on severely soda saline-alkali land. The two, together with the subsequent planting of switchgrass, constitute an inseparable and complete technical solution, reflecting the progressive ecological restoration logic of first restoring the environment and then producing forage.

[0017] Furthermore, the thickness of the salt crust removed in step (1) is 0.5 to 1.5 cm.

[0018] Technical Principle: The 0.5–1.5 cm layer is the main crystalline layer thickness for salt accumulation on the surface of severely saline-alkali land in spring. This layer has the highest salt concentration (electrical conductivity reaching 73.27 mS / cm), while the soil salinity below it is relatively low. Removing this layer can remove most of the surface salt accumulation without disturbing the underlying soil. The removal process can be carried out using a plastic steel snowplow, which is lightweight, has a sharp blade, does not damage the topsoil structure, and is low in cost and allows for a large working area per person, making it suitable for the treatment of large, scattered patches in severely saline-alkali areas.

[0019] Furthermore, the time for manually removing the salt crust layer in step (1) is from late April to early May, which is the end of spring and the beginning of summer.

[0020] Technical principle: Late April to early May is the period when the permafrost in Northeast China has completely thawed, temperatures are rising, and the rainy season has not yet arrived. Surface evaporation is intense, and the salt crust forms most stably and firmly, making it easy to remove mechanically or manually. If this period occurs earlier, the permafrost is not thawed, making removal difficult; if it occurs later, rain leaching will cause the salt crust to redissolve and infiltrate, losing the optimal window for physical removal.

[0021] Furthermore, the organic fertilizer mentioned in step (2) is cow manure that has undergone composting and fermentation, and the application rate is 10-20 t / hm. 2 .

[0022] Technical Principle: Cow manure is commonly used in saline-alkali grasslands, providing an abundant and inexpensive source. After composting and fermentation, it has a high organic matter content. When applied to rotary tillage, it increases soil porosity and improves permeability; the rich humus content can also absorb sodium. + Simultaneously, it activates indigenous functional microorganisms. And 10–20 t / hm 2 The application rate is moderate, which can effectively improve the soil in the 0-30 cm topsoil layer, while avoiding excessive application that could lead to nutrient imbalance or excessive costs.

[0023] Furthermore, in step (3), after sowing Suaeda salsa, no soil covering or only shallow soil covering is performed, and the seeds are sown evenly by broadcasting.

[0024] Technical principle: Suaeda salsa seeds are small and have a low thousand-seed weight. Broadcasting ensures even distribution of seeds per unit area, creating a covering advantage. No soil covering or only shallow soil covering is used because Suaeda salsa seeds require light to germinate, and the surface soil of saline-alkali soil has low moisture content and high salt content. Deep burial would cause the seeds to lose viability due to high osmotic stress. Shallow sowing utilizes the slightly moist surface layer in spring to promote germination.

[0025] Furthermore, the transplanting time for the willow branch millet seedlings mentioned in step (4) is 2 months after the sowing of Suaeda salsa, that is, from early to mid-July.

[0026] Technical principle: At this time, Suaeda salsa has entered its vigorous growth period. Through root absorption and surface mulching, it significantly reduces the local soil pH and salinity. With the arrival of the rainy season in Northeast China, natural rainfall washes away the surface salts, resulting in suitable soil moisture. The gaps between Suaeda salsa plants form a sheltered microenvironment, providing low-salt and moist conditions for the establishment of switchgrass seedlings. This conforms to the temporal logic of ecological succession: pioneer species improve habitats—establishing species enter.

[0027] Furthermore, the harvesting time in step (5) is from the end of August to the beginning of September, and the Suaeda salsa is removed along with its roots during harvesting.

[0028] Technical principle: The peak period for biomass accumulation of Suaeda salsa and switchgrass is from late August to early September, and the rainy season is basically over. Removing Suaeda salsa with its roots can completely remove the salt absorbed and accumulated by the roots from the system (maximum desalination), while releasing light and space resources for switchgrass. Switchgrass can retain all plants to facilitate the return of nutrients to underground organs, ensuring safe overwintering and rapid greening in the following year.

[0029] Furthermore, it also includes step (6): during the growing season after the switchgrass turns green, regularly monitor soil salinity, pH value, organic matter content, as well as the growth dynamics and feed quality of the switchgrass.

[0030] Furthermore, the salt crust removed in step (1) is collected and sent to an industrial salt processing plant for resource utilization.

[0031] Furthermore, in step (5), after the willow sorghum turns green again the following year, irrigation is only supplemented under extreme drought conditions, and no more chemical fertilizers or chemical amendments are applied.

[0032] Compared with the prior art, the present invention has the following advantages and technical effects: This invention utilizes the peak season for spring salt return, directly reducing topsoil salt sources through physical desalination and breaking down soil compaction barriers. It leverages the salt-tolerant pioneer plant *Suaeda salsa* to actively absorb salt and lower pH, creating a low-salt microenvironment for subsequent crop growth. Furthermore, it introduces deep-rooted, high-quality switchgrass, producing high-protein forage while continuously improving the soil. This method aims to overcome the technical challenges of existing technologies—characterized by recurring treatments, high costs, and no economic output—and achieve a new sustainable utilization model for saline-alkali land that promotes treatment through application and generates output while restoring.

[0033] This invention differs from traditional passive salt washing or in-situ neutralization. It can accurately grasp the window of opportunity during the peak salt return period (late April to early May) when the salt crust has the best physical properties, low water content, and is easy to remove, thus achieving proactive source reduction. It also utilizes the salt accumulation and pH-lowering function of Suaeda salsa to create a safe micro-habitat for switchgrass, rather than relying on water-intensive leaching or costly chemical replacement. At the same time, it utilizes the deep root system and perennial characteristics of switchgrass, which only requires natural rainfall to maintain growth in the second year, completely getting rid of the cyclical investment dilemma of traditional soil improvement methods that require seasonal modifications.

[0034] This invention enables switchgrass to be successfully established on severely saline-alkali land where it would otherwise be impossible to survive, through physical desalination in step (1) and pioneer planting of Suaeda salsa in step (3). In contrast, in plots without physical desalination and Suaeda salsa improvement, the survival rate of switchgrass was 0% 15 days after transplanting, and all seedlings died due to high salt stress. This fully demonstrates that the three-step progressive strategy of physical desalination, pioneer desalination, and deep-rooted forage grass in this invention is a key technical path for the rapid conversion of severely saline-alkali land into high-quality forage grassland. Detailed Implementation

[0035] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0036] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0037] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0038] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0039] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0040] This invention provides a method for producing high-quality forage based on the ecological restoration of saline-alkali land. This method is used to establish switchgrass on severely soda-type saline-alkali land with a pH > 10.0, and includes the following steps: (1) For severely soda-type saline-alkali patches with pH>10.0, the accumulated salt crust layer on the surface is removed manually in spring; (2) Apply organic fertilizer to the soil after removing the salt crust layer, till and mix it evenly, and then irrigate until the soil is moist. (3) Sowing Suaeda salsa ( Blue-bellied toad Seeds, sowing rate is 15–30 kg / hm. 2 ; (4) After the Suaeda salsa enters its vigorous growth period, transplant Sorghum stenoptera (Salix matsudana) into the gaps between the plants. Panicum virgatum Seedlings, transplanting density is 20,000 to 30,000 plants / hm² 2 ; (5) Water management should be carried out according to the principle of supplementing water in the dry season and supplementing less water in the rainy season. At the end of the growing season of the year, Suaeda salsa should be pulled out and used for feeding after the willow branch millet turns green the following year.

[0041] In a preferred embodiment of the present invention, the thickness of the salt crust removed in step (1) is 0.5 to 1.5 cm.

[0042] In a preferred embodiment of the present invention, the time for manually removing the salt crust layer in step (1) is from late April to early May, which is the end of spring and the beginning of summer.

[0043] In a preferred embodiment of the present invention, the organic fertilizer in step (2) is cow manure that has undergone composting and fermentation, and the application rate is 10-20 t / hm. 2 .

[0044] In a preferred embodiment of the present invention, in step (3), after sowing Suaeda salsa, no soil covering or only shallow soil covering is performed, and the seeds are sown evenly by broadcasting.

[0045] In a preferred embodiment of the present invention, the transplanting time of the willow branch millet seedlings in step (4) is 2 months after the sowing of Suaeda salsa, that is, from early to mid-July.

[0046] In a preferred embodiment of the present invention, the harvesting time in step (5) is from the end of August to the beginning of September, and the Suaeda salsa is removed along with its roots during harvesting.

[0047] In a preferred embodiment of the present invention, step (6) is also included: during the growing season after the switchgrass turns green again, the soil salinity, pH value, organic matter content, and the growth dynamics and feed quality of the switchgrass are monitored regularly.

[0048] In a preferred embodiment of the present invention, the method is applicable to the severely saline-alkali soil area of ​​Songnen Plain. After a complete growing season of restoration, the desalination rate of the 0-30 cm soil layer reaches 60%-75%, and the vegetation coverage of switchgrass reaches 60% in one year.

[0049] In a preferred embodiment of the present invention, the salt crust removed in step (1) is collected and sent to an industrial salt processing plant for resource utilization.

[0050] In a preferred embodiment of the present invention, after the willow sorghum turns green again the following year in step (5), irrigation is only supplemented under extreme drought conditions, and no chemical fertilizers or chemical amendments are applied.

[0051] In a preferred embodiment of the present invention, in step (3), Suaeda salsa serves as a pioneer plant. During its growth period, it reduces the soil pH by 0.3 to 1.1 units and the surface conductivity by 20% to 70% through root absorption and surface covering.

[0052] In a preferred embodiment of the invention, switchgrass seedlings are obtained through seed propagation. The specific method is as follows: 60 days before transplanting, the seeds are pre-cooled at 5℃-10℃ for 10 days in a moist state to break dormancy. Seedling trays, preferably with 50 or 72 cells, are filled with substrate. The substrate is a mixture of peat moss and loam of equal volume, sieved through a 20-mesh sieve. After the substrate is thoroughly irrigated (relative moisture content of 40%-60%), sowing occurs, with 3-5 seeds sown per tray and covered with 8mm-10mm of substrate. The seedling temperature is maintained at 20℃-30℃, and the relative humidity at 60%-70%. Seedlings with well-developed root systems, a good root ball, good growth, no pests or diseases, a height of over 15cm, and at least 5 visible leaves are ready for transplanting. 2-3 seedlings are transplanted per cell.

[0053] The embodiments of the present invention were carried out in a severely degraded area of ​​the Momoge Wetland in western Jilin Province, where there was no vegetation cover and the pH was >10.0.

[0054] The technical solution of the present invention will be further illustrated by the following embodiments.

[0055] Example 1 A method for producing high-quality forage based on saline-alkali land ecological restoration is carried out in the following steps: (1) Physical removal of surface salt crust in spring From May 6 to 8, a severely soda-type saline-alkali soil patch was selected in the Momoge National Nature Reserve in Jilin Province. The ground was uncovered by vegetation and had a layer of salt crust on the surface. The salt crust with an accumulated thickness of 0.5 cm was manually removed and transported out. The tool used to remove the salt crust (or salt crust layer) was a plastic steel snow shovel. The experimental plot was 10 m × 10 m in size.

[0056] (2) Apply organic fertilizer After the salt crust is removed, the soil layer is exposed. Cow manure organic fertilizer is then applied at a rate of 20 t / hm². 2 Apply the appropriate amount to the saline-alkali land, use a rotary tiller to mix it evenly, then rake it flat and irrigate it thoroughly to keep the soil moist.

[0057] (3) Planting of Suaeda salsa seedlings and sowing of Suaeda salsa seedlings in spring Suaeda salsa was planted as the single dominant species using broadcast sowing at a rate of 30 kg / hm².2 That is, 100 m 2 Apply 0.3 kg of seeds.

[0058] (4) Propagation and colony building of *Symplocos spp.* and transplanting of *Symplocos spp.* in the gaps of *Suaeda salsa*.

[0059] During the peak growth period of Suaeda salsa (July 28th), after the Suaeda salsa forms a canopy, immediately replant switchgrass in the gaps. At this time, the soil moisture is good, and the surface salts are washed away by rainwater, which is conducive to the survival of switchgrass seedlings. Replant switchgrass in the gaps at a planting density of 30,000 seedlings / hm². 2 That is, 100 m 2 300 seedlings were transplanted. Switchgrass seedlings were obtained through seed propagation. Starting 60 days before transplanting, the seeds were pre-cooled at 5°C for 10 days in a moist environment to break dormancy. 72-cell trays were filled with an equal volume mixture of peat moss and loam as the substrate, sieved through a 20-mesh sieve. The substrate was thoroughly irrigated to a relative moisture content of approximately 50%. Sowing then occurred, with 5 seeds sown per cell, covered with 8-10 mm of substrate. The seedling temperature was maintained at approximately 20°C at night and 30°C during the day, with a relative humidity of approximately 65%. When the seedlings reached a height exceeding 15 cm, seedlings with well-developed root systems and at least 5 visible leaves were collected for transplanting. Three seedlings were transplanted per cell.

[0060] (5) Management and monitoring Water regularly. On August 30th of the first year, uproot and remove the Suaeda salsa to remove the salt. In July-August of the second year, harvest the switchgrass to obtain high-quality forage.

[0061] Comparative Example 1 On the same plot as in Example 1 (a severely soda-type saline-alkali soil patch in Jilin Momoge National Nature Reserve, pH>10.0, with a salt crust on the surface), the physical removal of the salt crust in step (1) was not performed, nor was the addition of organic fertilizer in step (2). At the same time (early May), Suaeda salsa seeds were sown and willow sorghum seedlings were transplanted (early July). The transplanting density and management methods (irrigation, water management, etc.) were consistent with those in Example 1.

[0062] Performance testing The results of measuring the water content, pH and electrical conductivity of the surface salt crust and the topsoil (0-15 cm) after the salt crust was removed in Example 1 are shown in Table 1.

[0063] Table 1. Moisture content, pH, and electrical conductivity of the surface salt crust and the topsoil after salt crust removal in Example 1. The unimproved soil in the severely degraded area of ​​Momoge Wetland in western Jilin Province was used as the control group. The test results of soil salinity and organic matter content in the second year after improvement in Example 1 are shown in Table 2.

[0064] Table 2 Soil remediation effects and forage yield and quality after implementation Note: The plant height, heading rate, and crude protein in the table refer to the average values ​​measured and calculated after sampling of switchgrass.

[0065] As shown in Table 1, in early May, surface salt crust and topsoil (0-15cm) after salt layer removal were collected in the Momoge National Nature Reserve in Jilin Province. The dry weight of salt crust removed was 1.935 t / hm². 2 According to the formula C≈G×K, where C represents salt content (g / kg), G represents conductivity (mS / cm), and K is a conversion factor (commonly used for sodium chloride with a conversion factor of 0.66-0.72), the total salt removal amount calculated using this formula is 93.57-102.08 kg / hm². 2 As shown in Table 2, in the second year after the implementation of Example 1, the soil pH decreased by 1.47 units, electrical conductivity decreased by 77.5%, total soil organic matter increased by 164%, and total nitrogen and total phosphorus increased by more than 100%. In untreated saline-alkali soils with a pH > 10, switchgrass could not grow normally when planted alone. When mixed with *Alternanthera philoxeroides* (Comparative Example 1), it achieved some coverage in the first year, but the effect was far lower than that of Example 1. Compared with the control and Comparative Example 1, vegetation growth and quality were improved. The application of this technology can realize the conversion of saline-alkali land into high-quality forage switchgrass grassland.

[0066] Compared with existing technologies, this invention directly reduces topsoil salt sources through physical desalination in spring, removing a total salt amount of 93.57~102.08 kg per hectare, thus cutting off the vicious cycle of salt return-leaching-re-salinization at the source. After a full growing season of restoration, the desalination rate of the 0~30 cm soil layer reaches 60%~75%, the soil pH decreases by 1.47 units, the exchangeable sodium percentage (ESP) decreases from 32.36% to 7.56% (a reduction of 76.6%), and the soil organic matter content increases by 164%. Simultaneously, the introduced switchgrass shows a 43.9% increase in plant height and a 131% increase in heading rate in the second year, while maintaining a crude protein content above 5.5%, achieving a rapid conversion of severely saline-alkali land into high-yield, high-quality forage grassland.

[0067] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing high-quality forage based on saline-alkali land ecological restoration, characterized in that, The method described is used to establish switchgrass on severely soda-type saline-alkali land with pH > 10.0, and includes the following steps: (1) For severely soda-type saline-alkali patches with pH>10.0, the accumulated salt crust layer on the surface is removed manually in spring; (2) Apply organic fertilizer to the soil after removing the salt crust layer, till and mix it evenly, and then irrigate until the soil is moist. (3) Sow Suaeda salsa seeds at a rate of 15–30 kg / hm². 2 ; (4) After the Suaeda salsa enters its vigorous growth period, transplant the seedlings of Sorghum stenoptera into the gaps between the plants, with a transplanting density of 20,000 to 30,000 plants / hm². 2 ; (5) Water management should be carried out according to the principle of supplementing water in the dry season and supplementing less water in the rainy season. At the end of the growing season of the year, Suaeda salsa should be pulled out and used for feeding after the willow branch millet turns green the following year.

2. The method for producing high-quality forage based on saline-alkali land ecological restoration according to claim 1, characterized in that, The thickness of the salt crust removed in step (1) is 0.5 to 1.5 cm.

3. The method for producing high-quality forage based on saline-alkali land ecological restoration according to claim 1, characterized in that, The time for manually removing the salt crust in step (1) is from late April to early May.

4. The method for producing high-quality forage grass based on saline-alkali land ecological restoration according to claim 1, characterized in that, The organic fertilizer mentioned in step (2) is cow manure that has been composted and fermented, and the application rate is 10-20 t / hm. 2 .

5. The method for producing high-quality forage based on saline-alkali land ecological restoration according to claim 1, characterized in that, In step (3), after sowing Suaeda salsa, no soil covering or only shallow soil covering is required; the seeds are sown evenly by broadcasting.

6. The method for producing high-quality forage grass based on saline-alkali land ecological restoration according to claim 1, characterized in that, The transplanting time for the *Salix matsudana* seedlings mentioned in step (4) is 2 months after the *Suaeda salsa* sowing.

7. The method for producing high-quality forage based on saline-alkali land ecological restoration according to claim 1, characterized in that, The cutting time mentioned in step (5) is from the end of August to the beginning of September. When cutting, the Suaeda salsa should be removed along with its roots.

8. The method for producing high-quality forage grass based on saline-alkali land ecological restoration according to claim 1, characterized in that, It also includes step (6): During the growing season after the switchgrass turns green, regularly monitor soil salinity, pH value, organic matter content, and the growth dynamics and feed quality of the switchgrass.

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