Method for jointly planting suaeda glauca and alfalfa in seed field suitable for severe saline-alkali soil

Abstract

The invention relates to the technical field of severe saline-alkali soil improvement and pasture seed production, in particular to a method for jointly planting a seed field through suaeda glauca and alfalfa, which comprises the steps of furrow ridge culture terrain construction, suaeda glauca planting and salinity regulation, alfalfa planting and protection and pasture seed field management. The salt concentration at the ditch bottom is reduced by using the transpiration of suaeda glauca and the salt absorption characteristic of the root system, and a growth environment is provided for alfalfa; shallow root systems of suaeda glauca and deep root systems of alfalfa form complementation, and salt distribution and water utilization are optimized; the compound improved fertilizer continuously improves the soil fertility and increases the seed yield. The method can effectively improve the severe saline-alkali soil, realizes efficient production of forage grass seeds, and achieves a win-win target of ecological and economic benefits.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of severe saline-alkali land improvement and forage grass seed production, and specifically relates to a method for jointly planting seed fields of Suaeda glauca and alfalfa suitable for severe saline-alkali land. BACKGROUND

[0002] With the continuous development of saline-alkali land improvement technology, using salt-tolerant plants for ecological restoration and agricultural development has become a research hotspot. Severe saline-alkali land poses a serious threat to plant growth due to its high salt content, low fertility, and harsh ecological environment. How to maximize economic benefits while improving saline-alkali land remains a technical challenge to be solved. Currently, existing technologies mainly focus on single plant planting or soil improvement measures, and lack of a coordinated optimization scheme for severe saline-alkali land improvement and efficient production of forage grass seeds, making it difficult to balance improvement effect and economic benefit.

[0003] Through retrieval, it is found that the patent with publication number CN106211846B, “Method for treating muddy coastal beach by planting Suaeda salsa, alfalfa and corn in stages”, realizes the gradual conversion of coastal saline soil to arable land through the planting of pioneer halophyte Suaeda salsa, salt-tolerant soil improvement plant alfalfa, and field crop corn in stages. However, in this technical solution, the planting of Suaeda salsa and alfalfa does not form a clear spatiotemporal configuration synergy, and the advantages of Suaeda glauca in salt absorption and transpiration are not fully utilized to protect the planting of alfalfa, which may result in a low survival rate of alfalfa in severe saline-alkali land environment. In addition, this method mainly focuses on the process of land improvement and does not fully consider the efficient production needs of forage grass seed fields, making it difficult to meet the dual goals of ecological improvement and economic benefit.

[0004] Another patent with publication number CN112293173B, “Method for planting Suaeda salsa in coastal muddy saline-alkali land and application”, realizes the high survival rate planting of Suaeda salsa in severe saline-alkali land by using composted organic fertilizer and / or agricultural straw for soil improvement in the planting plot, combined with irrigation management in different periods. However, this technical solution only focuses on the planting of Suaeda salsa and does not introduce other salt-tolerant plants (such as alfalfa) to form a root complementary effect, limiting its ability to improve severe saline-alkali land while achieving diversified economic output. In addition, although this method has some innovation in the use of fresh water and shallow underground salt water, it does not involve the specific implementation of joint planting of Suaeda glauca and alfalfa, making it difficult to be directly applied to the construction of forage grass seed fields.

[0005] The aforementioned problems indicate that existing saline-alkali land improvement technologies, especially in the joint cultivation of *Suaeda salsa* and alfalfa in severely saline-alkali environments, suffer from insufficient spatiotemporal synergy, underutilization of root complementarity, and inadequate fulfillment of the demand for high-efficiency forage seed production. Therefore, there is an urgent need for a planting method that combines the spatiotemporal synergy and root complementarity of *Suaeda salsa* and alfalfa to achieve the dual goals of severely saline-alkali land improvement and high-efficiency forage seed production, thereby satisfying the need for a win-win situation of ecological restoration and economic benefits. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method that achieves the dual goals of improving severely saline-alkali land and producing high-efficiency forage seeds by combining the spatiotemporal configuration synergy and root complementary effect of Suaeda salsa and alfalfa with furrow-ridge planting mode.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A method for establishing seed fields in severely saline-alkali land by jointly planting Suaeda salsa and alfalfa includes the following steps: Step 1: Constructing the terrain using furrows and ridges After preparing the surface of severely saline-alkali land, construct a furrow-ridge structure with a ridge width of 60-80cm and a furrow width of 40-60cm, and a ridge height of 15-25cm. Use machinery to flatten the ridge surface and furrow bottom to form a uniform height difference, which facilitates salt migration and moisture distribution regulation. Step 2: Cultivation and Salinity Control of Suaeda salsa Sow seeds of Suaeda salsa in rows on the ridges at a rate of 1.5–2.5 kg / mu and a sowing depth of 1–3 cm. During the growth period of Suaeda salsa, transpiration promotes the migration of soil salts from low to high places, while its roots absorb salts and reduce the salt concentration at the bottom of the furrow. Step 3: Alfalfa Establishment and Protection Salt-tolerant alfalfa seeds are sown in rows at the bottom of the furrow at a rate of 0.8–1.2 kg / mu and a sowing depth of 2–4 cm. Suaeda salsa acts as a pioneer plant during the one-year cycle, providing a salt barrier for alfalfa, protecting alfalfa establishment and promoting its root development. Step 4: Management of Forage Seed Fields After the Suaeda salsa matures, harvest it and remove the above-ground parts, leaving the alfalfa as a seed field for perennial forage. During the alfalfa growing season, apply compound fertilizer at a rate of 30-50 kg / mu to continuously improve soil structure and increase seed yield.

[0008] As a preferred technical solution, in step one, the furrow and ridge terrain construction uses a laser leveling instrument for precise land leveling to ensure that the slope of the ridge surface and the bottom of the furrow is controlled within 1% to 3% in order to optimize the water flow path and avoid water accumulation or salt backflow.

[0009] As a preferred technical scheme, in the step two, the seed of Suaeda glauca is treated by biological coating, and the coating material comprises the following components in parts by weight: 10-20 parts of sodium alginate; 5-10 parts of humic acid; 3-8 parts of potassium dihydrogen phosphate; and 2-5 parts of trace element mixture.

[0010] As a preferred technical scheme, in the step three, the seed of alfalfa is selected from a variety with deep root system characteristics, such as Algonquin and WL343HQ, and the root system depth can reach 150-200 cm, which is complementary to the shallow root system of Suaeda glauca, and further optimizes the distribution of soil salt and the water use efficiency.

[0011] As a preferred technical scheme, in the step four, the composite improved fertilizer comprises the following components in parts by weight: 20-30 parts of fermented cow dung; 10-20 parts of shell powder; 5-10 parts of magnesium sulfate; 3-8 parts of borax; and 5-10 parts of microbial agent, which can significantly increase the soil organic matter content and promote the activity of alfalfa nodule bacteria, thereby improving the seed yield.

[0012] Due to the adoption of the above technical scheme, the present application has the following beneficial effects: (1) By the design of the ridge and furrow topography, the transpiration and salt absorption capacity of Suaeda glauca on the ridge surface effectively reduces the salt concentration at the bottom of the furrow, and provides a suitable growth environment for the planting of alfalfa; at the same time, the annual characteristic of Suaeda glauca makes it be removed after completing the improvement task, avoiding the competition influence on the growth of alfalfa.

[0013] (2) The root system complementary effect of Suaeda glauca and alfalfa significantly optimizes the distribution of soil salt and the water use efficiency, and the shallow root system of Suaeda glauca mainly absorbs the surface salt, while the deep root system of alfalfa can penetrate deep into the ground to improve the deep soil structure, forming a stable ecological improvement system.

[0014] (3) The application of the composite improved fertilizer not only continuously improves the soil fertility, but also enhances the nitrogen fixation ability of alfalfa nodule bacteria through the microbial agent, improves the seed yield of pasture, and realizes the win-win goal of the improvement of severe saline-alkali land and economic benefits. DETAILED DESCRIPTION

[0015] The application provides a method for constructing a seed field by combining Suaeda glauca and alfalfa on a severe saline-alkali land. The method can achieve the dual goals of land improvement and efficient production of pasture seeds. First of all, the specific operation process of land formation and the selection basis of related parameters need to be clarified during the implementation process. After the surface of the severe saline-alkali land is prepared, a ridge and furrow structure is constructed according to a ratio of 60 to 80 centimeters for the ridge width and 40 to 60 centimeters for the furrow width. The ridge height is controlled between 15 to 25 centimeters. The design of the ridge and furrow ratio and height is the best range verified by multiple experiments, which can effectively promote the optimization of water flow path and avoid the problem of salt backflow. In order to ensure the accuracy of land formation, it is recommended to use a laser land leveler for land preparation, and the slope of the ridge surface and the furrow bottom is strictly controlled between 1% to 3%. This slope range can ensure uniform water distribution and prevent water accumulation. In actual operation, special attention should be paid to the uniformity of the height difference when mechanically flattening the ridge surface and the furrow bottom, in order to lay a foundation for subsequent salt migration and water regulation.

[0016] Next is the specific implementation process of Suaeda glauca planting and salt regulation. When sowing Suaeda glauca seeds on the ridge surface, the seeding rate should be controlled within 1.5 to 2.5 kilograms per mu, and the seeding depth is set to 1 to 3 centimeters. This combination of seeding rate and depth can ensure a high germination rate and growth stability of Suaeda glauca seeds in severe saline-alkali land. In order to further enhance the salt tolerance and germination ability of Suaeda glauca, the seeds need to be treated with biological coating. The coating materials include 10 to 20 parts of sodium alginate, 5 to 10 parts of humic acid, 3 to 8 parts of potassium dihydrogen phosphate, and 2 to 5 parts of trace element mixture. The ratio of these components has been verified by experiments, which can form a protective film on the surface of the seeds, effectively isolate salt invasion and provide necessary nutritional support. During the growth of Suaeda glauca, its transpiration will promote the migration of salt in the soil from low to high, and its shallow root system can absorb the surface salt, thereby significantly reducing the salt concentration in the furrow bottom. This process can be quantitatively described by the following formula: salt migration amount = transpiration rate x time x salt concentration gradient, where the transpiration rate is affected by environmental temperature and humidity, and the salt concentration gradient is determined by the design of the ridge and furrow structure.

[0017] At the same time or later stage of the planting of Suaeda glauca, it is necessary to sow salt-tolerant alfalfa seeds in the ditch bottom at a rate of 0.8 to 1.2 kg per mu, and the sowing depth is set to 2 to 4 cm. The selection of alfalfa seeds is crucial, and it is recommended to use varieties with deep root characteristics such as Algonquin or WL343HQ, which have root depth of 150 to 200 cm, complementing the shallow root system of Suaeda glauca. Suaeda glauca as an annual pioneer plant provides important salt barrier for alfalfa during its life cycle, enabling alfalfa to complete the planting and gradually develop its deep root system in a more suitable environment. This spatiotemporal configuration synergy mechanism not only optimizes the distribution of soil salt, but also improves water use efficiency, laying a solid foundation for the multi-year growth of subsequent alfalfa. In practical applications, the salt absorption capacity of Suaeda glauca and the root development of alfalfa can be evaluated by regularly monitoring the soil salt distribution and root growth depth.

[0018] When Suaeda glauca matures, its aboveground parts need to be harvested and removed in time to avoid competition with alfalfa growth. At this time, alfalfa has entered the multi-year seed field stage of pasture, and needs scientific management and maintenance. During the growth period of alfalfa, the application of compound modified fertilizer is one of the key links, and the fertilizer dosage is 30 to 50 kg per mu. The formula of the compound modified fertilizer includes fermented cow dung 20 to 30 parts, shell powder 10 to 20 parts, magnesium sulfate 5 to 10 parts, borax 3 to 8 parts, and microbial agent 5 to 10 parts. The reasonable combination of these components can significantly increase the soil organic matter content and promote the activity of alfalfa rhizobium, thereby improving seed yield. Among them, the microbial agent plays a particularly prominent role, which can enhance the nitrogen fixation ability of alfalfa rhizobium, thereby improving soil fertility. The effect of this fertilizer can be quantitatively evaluated by the following formula: Soil fertility improvement amount = organic matter increase amount + nitrogen fixation amount × time Where the organic matter increase amount is determined by fermented cow dung and shell powder, and the nitrogen fixation amount is closely related to the activity of microbial agent.

[0019] In specific application scenarios, the technical solutions of the present application can be widely applied in the fields of severe saline-alkali land improvement and pasture seed production. For example, when implementing the method in a certain severe saline-alkali area, first, the furrow and ridge structure is accurately constructed by a laser land leveler, and the soil preparation work is strictly carried out according to the above parameters. Then, the gray-green Suaeda species seeds treated by biological coating are sown on the ridge surface, and the salt-tolerant alfalfa seeds are sown in the ditch bottom. During the growth of gray-green Suaeda, the soil salt distribution and water flow conditions are monitored regularly to verify the transpiration effect and salt absorption effect. After the gray-green Suaeda matures, the aboveground part is harvested and removed, and the alfalfa is retained as a perennial pasture seed field. During the growth period of alfalfa, composite improved fertilizer is applied, and the root system development and seed yield changes are observed regularly. Through the above steps, not only the soil structure of severe saline-alkali land can be significantly improved, but also the efficient production of pasture seeds can be realized, and finally the win-win goal of ecological improvement and economic benefit is achieved.

[0020] In addition, the technical solutions of the present application can also be combined with other improvement measures for comprehensive application. For example, during the construction of the furrow and ridge terrain, the drip irrigation system can be used for precise irrigation to further optimize the water use efficiency. During the growth period of gray-green Suaeda and alfalfa, unmanned aerial vehicle remote sensing technology can be introduced for real-time monitoring to adjust the management strategy in time. Through the combination use of these auxiliary means, the practical application effect of the present method can be further improved, and more comprehensive technical support can be provided for the sustainable utilization of severe saline-alkali land. It should be noted that in actual operation, the related parameters need to be adjusted appropriately according to the specific geographical environment and climate conditions to ensure the adaptability and feasibility of the technical solutions.

Claims

1. A method for establishing seed fields by jointly planting Suaeda salsa and alfalfa in severely saline-alkali land, characterized in that, Includes the following steps: Step 1: Constructing the terrain using furrows and ridges After preparing the surface of severely saline-alkali land, construct a furrow-ridge structure with a ridge width of 60 to 80 cm and a furrow width of 40 to 60 cm. The ridge height is 15 to 25 cm. Use machinery to flatten the ridge surface and the bottom of the furrow to form a uniform height difference. Step 2: Cultivation and Salinity Control of Suaeda salsa Sow the seeds of Suaeda salsa in rows on the ridges at a rate of 1.5 to 2.5 kg per mu and at a depth of 1 to 3 cm. Step 3: Alfalfa Establishment and Protection Sow salt-tolerant alfalfa seeds in rows at the bottom of the furrow, with a sowing rate of 0.8 to 1.2 kg per mu and a sowing depth of 2 to 4 cm. Step 4: Management of Forage Seed Fields After the Suaeda salsa matures, harvest it and remove the above-ground parts. Keep the alfalfa as a seed field for perennial forage grass. Apply compound fertilizer during the alfalfa growing season at a rate of 30 to 50 kilograms per acre. The seeds of Suaeda salsa are treated with a biological coating material, which includes the following components in parts by weight: 10 to 20 parts sodium alginate, 5 to 10 parts humic acid, 3 to 8 parts potassium dihydrogen phosphate, and 2 to 5 parts a mixture of trace elements.

2. The method for jointly establishing seed fields of *Suaeda salsa* and alfalfa in severely saline-alkali land as described in claim 1, characterized in that... In step one, a laser leveler is used to precisely level the land, ensuring that the slope of the ridges and the bottom of the furrows is controlled between 1% and 3%.

3. The method for jointly establishing seed fields of *Suaeda salsa* and alfalfa in severely saline-alkali land as described in claim 1, characterized in that... In step three, alfalfa seeds are selected from varieties with deep root systems, with a root depth of 150 to 200 centimeters.

4. The method for jointly establishing seed fields of *Suaeda salsa* and alfalfa in severely saline-alkali land as described in claim 1, characterized in that... In step four, the compound improved fertilizer includes the following components in parts by weight: 20 to 30 parts fermented cow manure, 10 to 20 parts shell powder, 5 to 10 parts magnesium sulfate, 3 to 8 parts borax, and 5 to 10 parts microbial inoculant.

5. The method for jointly establishing seed fields of *Suaeda salsa* and alfalfa in severely saline-alkali land as described in claim 1, characterized in that... In step one, the ratio of ridge width to furrow width in the furrow-ridge structure is 1.5:1 to 2:

1.

6. The method for jointly establishing seed fields of *Suaeda salsa* and alfalfa in severely saline-alkali land as described in claim 1, characterized in that... In step two, the sowing depth of Suaeda salsa seeds is 2 cm.

7. The method for jointly establishing seed fields of *Suaeda salsa* and alfalfa in severely saline-alkali land as described in claim 1, characterized in that... In step three, the alfalfa seeds are sown at a depth of 3 cm.

8. The method for jointly establishing seed fields of *Suaeda salsa* and alfalfa in severely saline-alkali land as described in claim 1, characterized in that... In step four, the application rate of compound improved fertilizer is 40 kg per mu.

9. The method for jointly establishing seed fields of *Suaeda salsa* and alfalfa in severely saline-alkali land as described in claim 1, characterized in that... In step four, the microbial agent in the compound improved fertilizer is a nitrogen-fixing bacterial agent.