Semi-arid region saline-alkali soil improvement method for improving plant diversity

Abstract

The invention discloses a semi-arid region saline-alkali soil improvement method for improving plant diversity. The method comprises the following steps: S1, construction of a treatment unit; s2, arranging treatment units; s3, soil preliminary treatment; s4, planting plants; and S5, soil strengthening treatment. The complete treatment method is provided for solving the problems that the saline-alkali soil in the semi-arid area is high in saline-alkali degree and lack of species, a treatment system is formed by arranging a plurality of treatment units, the treatment system is matched with a special soil conditioner, the high saline-alkali degree of the saline-alkali soil in the semi-arid area can be relieved, and the saline-alkali soil in the semi-arid area can be improved. Meanwhile, a phytoremediation system with the suaeda glauca as the main part is carried, the biodiversity of the exposed saline-alkali soil in the semi-arid region can be further effectively improved, other factors such as rainfall are comprehensively considered according to the influence of seasonal factors, and finally a treatment scheme with one year as the duration is formed; after the treatment is finished, the wetland can be selectively developed into ornamental wetlands or agricultural cultivated lands, so that the economic value is higher.

Description

Technical Field

[0001] The present invention relates to the technical field of soil ecological improvement, and in particular to a method for improving saline-alkali soil in semi-arid areas for improving plant diversity. Background Art

[0002] Saline-alkali land is a type of salt accumulation, which means that the salt content in the soil affects the normal growth of crops. The formation of alkaline soil and alkaline soil is mostly related to the accumulation of carbonates in the soil. Therefore, the alkalinity is generally high, and plants can hardly survive in severe saline-alkali land.

[0003] The main methods for saline-alkali land management include physical management, chemical management, biological management and comprehensive management measures.

[0004] Physical treatment measures: transform saline-alkali soil through physical methods, such as covering with sand and soil, deep plowing and turning, ground covering, etc. Covering with sand and soil is to cover the saline-alkali land with loose porous materials such as blast furnace slag, coal ash slag, etc., to reduce soil salinity and alkalinity and improve soil fertility. Deep plowing and turning deepens the soil layer, promotes the formation of aggregate structure, increases soil porosity, and enhances soil permeability.

[0005] Chemical treatment measures: Use improvers such as gypsum and black alum to reduce or eliminate the alkali in the soil and improve the physical and chemical properties of the soil. These chemical improvers can improve soil structure and promote plant growth.

[0006] Biological control measures: Improve soil fertility, soil structure, and farmland microclimate, reduce surface water evaporation, and inhibit salt return by planting salt-tolerant plants, afforestation, and applying bacterial fertilizers.

[0007] Comprehensive treatment measures: Combine physical, chemical and biological methods, and use various measures according to specific circumstances to achieve the best improvement effect. For example, establish a complete drainage and irrigation system, strengthen water management, strictly control groundwater levels, and wash and remove salt from the soil through irrigation, flood diversion and silt release.

[0008] These treatment methods usually need to be selected and combined according to specific circumstances to achieve the best improvement effect. Seasonal changes also have a great impact on the salt content of saline-alkali land, but there is currently a lack of comprehensive treatment methods that take into account seasonal effects. The invention patent with patent publication number CN108966718A discloses a saline-alkali land improvement method, including the following steps: A. deep plowing and leveling the saline-alkali land; B. draining salt from the leveled saline-alkali land through underground pipes; C. irrigating the saline-alkali land after laying the underground pipes; D. applying soil directional conditioners to the treated saline-alkali land; E. planting salt-tolerant rice varieties. The physical structure of saline-alkali soil can be significantly improved, the total salt content of saline-alkali land can be reduced, the soil can be activated, water and fertilizer can be retained, the organic matter content of the soil can be increased, and the physical and chemical properties of saline-alkali soil can be changed, thereby achieving a long-term virtuous cycle of saline-alkali soil. However, it does not take into account the impact of seasonality. For different salt contents in different seasons, it is difficult for actual treatment measures to achieve the described effects, and there is also a lack of research on the diversity of saline-alkali land plants. Summary of the invention

[0009] In view of the above-mentioned problems, the present invention provides a method for improving saline-alkali soil in semi-arid areas for enhancing plant diversity.

[0010] The technical solution of the present invention is:

[0011] A method for improving saline-alkali soil in semi-arid areas for improving plant diversity comprises the following steps:

[0012] S1. Construction of treatment units: Divide the bare land to be treated into several treatment units. In each treatment unit, from upstream to downstream, there are terrestrial plant planting areas, alkali canopy planting areas, and aquatic plant planting areas. A first drainage channel is excavated on both sides and inside the terrestrial plant planting area, and a second drainage channel is excavated on both sides and inside the alkali canopy planting area. The second drainage channel is connected to the aquatic plant planting area.

[0013] S2, arrangement of treatment units: a plurality of the treatment units are arranged in sequence in the longitudinal direction to form a treatment unit strip, and a plurality of the treatment unit strips are arranged in sequence in the transverse direction, and the alkali canopy planting area and the aquatic plant planting area in two adjacent treatment unit strips are aligned with each other, and underground concealed pipes perpendicular to the treatment unit strips are laid below the alkali canopy planting area and the aquatic plant planting area;

[0014] S3. Preliminary soil treatment: From March to May, water is sequentially injected into the first drainage channel of the upstreammost treatment unit in each treatment unit strip, so that the water depth of the aquatic plant planting area in each treatment unit is not less than 40%, and then soil conditioner is mixed into the terrestrial plant planting area, and the mixing amount is 60-80kg / mu;

[0015] S4, Planting: In March to May, and within 10 to 15 days after the completion of the initial soil treatment in S3, plant terrestrial plants in the terrestrial plant planting area, plant alkali canopy in the alkali canopy planting area, and plant aquatic plants in the aquatic plant planting area. After 15 to 20 days, water is sequentially injected into the first drainage channel of the most upstream treatment unit in each treatment unit strip, so that the water depth in the aquatic plant planting area in each treatment unit is not less than 60%;

[0016] S5. Soil strengthening management: From June to September, local water replenishment and drainage combined with rainfall are used to maintain the water depth of the aquatic plant planting area in each management unit at 60-70%. From October to March of the following year, local water replenishment and drainage combined with rainfall are used to maintain the water depth of the aquatic plant planting area in each management unit at 20-30%.

[0017] While S3 to S5 are being carried out, the collected salt water is discharged through underground pipes.

[0018] Furthermore, within one of the management units, the first drainage channels on both sides and the second drainage channels on both sides are connected to each other, there are 2 to 4 first drainage channels inside the terrestrial plant planting area, there are 3 to 6 second drainage channels inside the alkali canopy planting area, and the first drainage channels and the second drainage channels are arranged crosswise.

[0019] Description: By optimizing the number and direction of the first drainage channel and the second drainage channel, the irrigation of the treatment unit can be more uniform, the salt can be carried effectively, and it is conducive to the subsequent salt accumulation and dredging.

[0020] Furthermore, the area ratio of the terrestrial plant planting area, the alkali canopy planting area, and the aquatic plant planting area is 1:1-1.5:2-3, and the depth of the aquatic plant planting area is 30-40 cm.

[0021] Description: Rationally allocate the number of crop types by optimizing the area of ​​each planting area.

[0022] Furthermore, each of the governance unit stripes includes 5 to 20 governance units, and the number of governance unit strips is 3 to 10.

[0023] Note: By optimizing the number of governance unit strips and the number of governance units, the irrigation effect and desalination effect are guaranteed, and the transformation of subsequent governance units is facilitated.

[0024] Furthermore, the soil conditioner in S3 is a mixture of desulfurized gypsum, sheep manure, and modified biochar in a mass ratio of 1:1:2 to 3.

[0025] Description: Soil conditioners can be used to investigate the physical and chemical properties of soil, which is beneficial to crop growth.

[0026] Furthermore, the preparation method of the biochar is as follows: the reeds in S5 are harvested as the biomass raw material of the biochar, the harvesting period is divided into two periods, the first period is the growing period of March to April, and the second period is the end of the maturity period, the reeds harvested twice are mixed in a mass ratio of 1:1, cut into 1-3 cm small segments, soaked in a sulfuric acid solution with a mass concentration of 30-40% for 48±1h, taken out and washed with deionized water to a pH of 7±0.2 to obtain acidified reed segments, the acidified reed segments are dried in an oven at 50-60°C, and then crushed for 10 0-120 mesh sieve to obtain acidified reed powder, soak the acidified reed powder in a Fe(NO3)3 solution with a molar concentration of 0.3-0.5, adjust the mass ratio of the acidified reed powder to the pure iron in the Fe(NO3)3 solution to 20-25:1, soak for 12 hours, place them together in a high-pressure reactor, keep them warm at 220-260°C for 4-6 hours under the condition of continuous N2 introduction, take out the solid-liquid mixture, wash it with anhydrous ethanol and filter it to obtain solid powder, dry the solid powder in an oven at 45-55°C to obtain biochar.

[0027] Description: Through the optimization of the preparation method of biochar, not only can the reeds planted in the aquatic plant planting area be utilized to realize local materials, but also the biochar preparation method is improved according to the characteristics of the reeds and the needs of saline-alkali land management. Through acidification and iron-modified hydrothermal methods, the adsorption capacity and activity of biochar can be improved, which can effectively improve the high-salt environment in saline-alkali land.

[0028] Furthermore, the terrestrial plants in S4 are one or more of Siberian canopus, salt claw, sedge, and Achnatherum splendens, and the aquatic plants are reeds. The seed dosage of terrestrial plants, alkali canopy, and aquatic plants during planting is 7-8 kg / mu, and the plant distance between terrestrial plants and alkali canopy is maintained at 5-6 cm.

[0029] Description: By using alkali canopy as the main improved crop, supplemented by other terrestrial plants and aquatic plants, the environment of saline-alkali bare land can be effectively improved, thereby playing a good role in improving the subsequent plant diversity.

[0030] Furthermore, the underground pipe has a diameter of 100 to 120 mm, the pipe body of the underground pipe is provided with micropores of 0.5 to 1 mm, the material of the underground pipe is PVC or PE, the buried depth of the underground pipe is 1 to 2 m, and filter material is laid on the top of the underground pipe.

[0031] Description: Optimize the characteristics of underground pipes to ensure that they can effectively collect water and have a sufficient service life.

[0032] Furthermore, both ends of each of the underground concealed pipes extend outside the treatment unit strips located on both sides, and a water pump is provided at one end of the underground concealed pipe.

[0033] Note: Optimize the length of underground pipes to ensure that they can effectively collect water from salt accumulation.

[0034] The beneficial effects of the present invention are:

[0035] (1) The method for improving saline-alkali land in semi-arid areas for improving plant diversity of the present invention is aimed at the problems of high salinity and alkalinity of saline-alkali land in semi-arid areas and lack of plant species, and provides a complete treatment method. By arranging multiple treatment units to form a treatment system, combined with the special soil conditioner of the present invention, the high salinity and alkalinity of saline-alkali land in semi-arid areas can be alleviated. At the same time, the plant restoration system mainly based on alkali canopy can further effectively improve the biodiversity of exposed saline-alkali land in semi-arid areas. According to the influence of seasonal factors, other factors such as rainfall are comprehensively considered, and finally a treatment plan with a duration of one year is formed. After the treatment is completed, it can be selectively developed into ornamental wetlands or agricultural arable land, which has great economic value.

[0036] (2) The method for improving saline-alkali land in semi-arid areas for enhancing plant diversity of the present invention can effectively improve the environment of bare saline-alkali land by using alkali canopy as the main improved crop, supplemented by other terrestrial plants and aquatic plants, thereby having a good improvement effect on the subsequent plant diversity; and through the preferred method for preparing biochar, not only can the reeds planted in the aquatic plant planting area be utilized to achieve local material resources, but also the biochar preparation method is improved according to the characteristics of the reeds and the needs of saline-alkali land management, and the adsorption capacity and activity of the biochar can be improved by acidification and iron-modified hydrothermal methods, and the two harvests of reeds can not only ensure a high cellulose content, but also control the growth rate of reeds in the aquatic plant planting area, which can effectively improve the high salt environment in the saline-alkali land. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the strip distribution of treatment units of a method for improving saline-alkali land in semi-arid areas for improving plant diversity according to the present invention;

[0038] Figure 2 It is a schematic diagram of the internal structure of a treatment unit of a method for improving saline-alkali land in semi-arid areas for improving plant diversity according to the present invention;

[0039] Figure 3 It is a schematic diagram of vegetation coverage and plant diversity of various comparative experiments in an experimental example of a method for improving saline-alkali land in a semi-arid area for improving plant diversity of the present invention;

[0040] Figure 4It is a schematic diagram of soil physical and chemical indicators of various comparative experiments in an experimental example of a method for improving saline-alkali land soil in a semi-arid region for improving plant diversity of the present invention;

[0041] Figure 5 The present invention is a method for improving saline-alkali land soil in semi-arid areas for improving plant diversity. In the experimental example, the bare land condition of saline-alkali land in semi-arid areas is treated according to the method of Example 1;

[0042] Figure 6 This is a method for improving saline-alkali land in semi-arid areas for improving plant diversity in an experimental example of the present invention, in which the bare land condition of saline-alkali land in semi-arid areas is treated according to the method of Example 1.

[0043] Among them, 1-terrestrial plant planting area, 11-first drainage channel, 2-alkali canopy planting area, 21-second drainage channel, 3-aquatic plant planting area, 4-underground concealed pipe. DETAILED DESCRIPTION

[0044] Example 1

[0045] A method for improving saline-alkali soil in semi-arid areas for improving plant diversity comprises the following steps:

[0046] S1. Construction of governance units: Divide the bare land to be governed into several governance units, such as Figure 2 As shown, in each treatment unit, from the upstream direction to the downstream direction, there are terrestrial plant planting area 1, alkali canopy planting area 2, and aquatic plant planting area 3. The first drainage channel 11 is excavated on both sides and inside of the terrestrial plant planting area 1, and the second drainage channel 21 is excavated on both sides and inside of the alkali canopy planting area 2. The second drainage channel 21 is connected with the aquatic plant planting area 3. In one treatment unit, the first drainage channels 11 on both sides and the second drainage channels 21 on both sides are connected to each other. There are two first drainage channels 11 in the terrestrial plant planting area 1, and there are three second drainage channels 21 in the alkali canopy planting area 2, and the first drainage channels 11 and the second drainage channels 21 are arranged crosswise.

[0047] S2. Governance unit arrangement: Figure 1 As shown, 10 treatment units are arranged in sequence in the longitudinal direction to form a treatment unit strip, and 5 treatment unit strips are arranged in sequence in the transverse direction. At the same time, the alkali canopy planting area 2 and the aquatic plant planting area 3 in two adjacent treatment unit strips are aligned with each other, and an underground concealed pipe 4 perpendicular to the treatment unit strip is laid below the alkali canopy planting area 2 and the aquatic plant planting area 3. The area ratio of the terrestrial plant planting area 1, the alkali canopy planting area 2, and the aquatic plant planting area 3 is 1:1.3:2.5, and the depth of the aquatic plant planting area 3 is 35 cm;

[0048] S3. Preliminary soil treatment: In March, water was injected into the first drainage channel 11 of the most upstream treatment unit in each treatment unit strip in turn, so that the water depth of the aquatic plant planting area 3 in each treatment unit was 50%, and then soil conditioner was mixed into the terrestrial plant planting area 1, with a mixing amount of 75 kg / mu. The soil conditioner was a mixture of desulfurized gypsum, sheep manure, and modified biochar in a mass ratio of 1:1:2;

[0049] The preparation method of biochar is as follows: the reeds in S5 are harvested as the biomass raw material of biochar, and the harvesting period is divided into two periods, the first period is the growing period of March, and the second period is the end of the maturity period. The reeds harvested twice are mixed in a mass ratio of 1:1, cut into 2 cm small segments, and soaked in a sulfuric acid solution with a mass concentration of 35% for 48 hours. After being taken out, they are washed with deionized water to a pH of 7 to obtain acidified reed segments, and the acidified reed segments are dried in an oven at 55°C, and then crushed through 110 mesh sieve to obtain acidified reed powder, soak the acidified reed powder in a Fe(NO3)3 solution with a molar concentration of 0.4, adjust the mass ratio of the acidified reed powder to the pure iron in the Fe(NO3)3 solution to 23:1, soak for 12 hours, place them together in a high-pressure reactor, keep them warm at 240°C for 5 hours under the condition of continuous N2 flow, take out the solid-liquid mixture, wash it with anhydrous ethanol and filter it to obtain a solid powder, dry the solid powder in an oven at 50°C to obtain biochar;

[0050] S4, plant planting: in March, and within 10 days after the completion of the initial soil treatment in S3, terrestrial plants are planted in the terrestrial plant planting area 1, alkali canopy is planted in the alkali canopy planting area 2, and aquatic plants are planted in the aquatic plant planting area 3. After 15 days, water is sequentially injected into the first drainage channel 11 of the most upstream treatment unit in each treatment unit strip, so that the water depth of the aquatic plant planting area 3 in each treatment unit is 70%. The terrestrial plants are sedge and Achnatherum splendens, and the aquatic plants are reeds. The seed dosage of terrestrial plants, alkali canopy and aquatic plants during planting is 7kg / mu, and the plant distance between terrestrial plants and alkali canopy is maintained at 5cm;

[0051] S5. Soil strengthening and management: From June to September, local water replenishment and drainage combined with rainfall are used to maintain the water depth of the aquatic plant planting area 3 in each management unit at 62%. From October to March of the following year, local water replenishment and drainage combined with rainfall are used to maintain the water depth of the aquatic plant planting area 3 in each management unit at 24%.

[0052] While S3 to S5 are being carried out, the collected salt water is discharged through the underground pipe 4. The diameter of the underground pipe 4 is 110 mm. The pipe body of the underground pipe 4 is provided with 0.7 mm micropores. The material of the underground pipe 4 is PVC or PE. The buried depth of the underground pipe 4 is 1.5 m. Filter material is laid on the top of the underground pipe 4. The filter material is expanded clay with a particle size of 5 mm. Both ends of each underground pipe 4 extend outside the treatment unit strips on both sides. A water pump is provided at one end of the underground pipe 4.

[0053] Example 2

[0054] The difference between this embodiment and embodiment 1 is that:

[0055] There are three first drainage channels 11 in the terrestrial plant planting area 1, and four second drainage channels 21 in the alkali canopy planting area 2. The area ratio of the terrestrial plant planting area 1, the alkali canopy planting area 2, and the aquatic plant planting area 3 is 1:1:2. The depth of the aquatic plant planting area 3 is 30 cm. Each management unit strip includes 5 management units, and the number of management unit strips is 3.

[0056] Example 3

[0057] The difference between this embodiment and embodiment 1 is that:

[0058] There are 4 first drainage channels 11 in the terrestrial plant planting area 1, and 6 second drainage channels 21 in the alkali canopy planting area 2. The area ratio of the terrestrial plant planting area 1, the alkali canopy planting area 2, and the aquatic plant planting area 3 is 1:1.5:3. The depth of the aquatic plant planting area 3 is 40 cm. Each management unit strip includes 20 management units, and the number of management unit strips is 10.

[0059] Note: In the actual treatment process, the number of treatment unit strips and treatment units should be reasonably allocated according to the size of the bare saline-alkali land and the salt content. When the area of ​​the bare saline-alkali land is large, the number and size of the treatment units should be appropriately increased. When the salt content of the bare saline-alkali land is high, the area of ​​the alkali canopy planting area 2 and the aquatic plant planting area 3 should be appropriately increased, and the number of the first drainage channel 11 and the second drainage channel 21 should be appropriately increased to promote drainage effect and improve the leaching rate of accumulated salt.

[0060] Example 4

[0061] The difference between this embodiment and embodiment 1 is that:

[0062] The soil conditioner is a mixture of desulfurized gypsum, sheep manure, and modified biochar in a mass ratio of 1:1:3;

[0063] The preparation method of biochar is as follows: the reeds in S5 are harvested as the biomass raw material of biochar, and the harvesting period is divided into two stages, the first stage is when the growth is in March, and the second stage is at the end of the maturity stage. The reeds harvested twice are mixed in a mass ratio of 1:1, cut into 1 cm small segments, and immersed in a sulfuric acid solution with a mass concentration of 30% for 47 hours. After being taken out, they are washed with deionized water to a pH of 6.8 to obtain acidified reed segments, and the acidified reed segments are dried in an oven at 50°C, and then crushed over 100 The acidified reed powder was sieved through a mesh sieve to obtain acidified reed powder, and the acidified reed powder was soaked in a Fe(NO3)3 solution with a molar concentration of 0.3, and the mass ratio of the acidified reed powder to the pure iron in the Fe(NO3)3 solution was adjusted to 20:1. After soaking for 12 hours, they were placed in a high-pressure reactor together, and kept warm at 220°C for 4 hours under the condition of continuous N2 introduction. The solid-liquid mixture was taken out, washed with anhydrous ethanol and filtered to obtain a solid powder, and the solid powder was dried in an oven at 45°C to obtain biochar.

[0064] Example 5

[0065] The difference between this embodiment and embodiment 1 is that:

[0066] The soil conditioner is a mixture of desulfurized gypsum, sheep manure, and modified biochar in a mass ratio of 1:1:3;

[0067] The preparation method of biochar is as follows: the reeds in S5 are harvested as the biomass raw material of biochar, and the harvesting period is divided into two stages, the first stage is when the growth is in April, and the second stage is at the end of the maturity stage. The reeds harvested twice are mixed in a mass ratio of 1:1, cut into 3 cm small segments, and immersed in a sulfuric acid solution with a mass concentration of 40% for 49 hours. After being taken out, they are washed with deionized water to a pH of 7.2 to obtain acidified reed segments, and the acidified reed segments are dried in an oven at 60°C, and then crushed for 120 The acidified reed powder was sieved through a mesh to obtain acidified reed powder, and the acidified reed powder was soaked in a Fe(NO3)3 solution with a molar concentration of 0.5, and the mass ratio of the acidified reed powder to the pure iron in the Fe(NO3)3 solution was adjusted to 25:1. After soaking for 12 hours, they were placed in a high-pressure reactor together, and kept warm at 260°C for 6 hours under the condition of continuous N2 introduction. The solid-liquid mixture was taken out, washed with anhydrous ethanol and filtered to obtain a solid powder, and the solid powder was dried in an oven at 55°C to obtain biochar.

[0068] Example 6

[0069] The difference between this embodiment and embodiment 1 is that:

[0070] The soil conditioner is a mixture of desulfurized gypsum, sheep manure, and modified biochar in a mass ratio of 1:1:2;

[0071] The preparation method of biochar is as follows: the reeds in S5 are harvested as the biomass raw material of biochar, and the harvesting period is divided into two stages, the first stage is when the growth is in April, and the second stage is at the end of the maturity period. The reeds harvested twice are mixed in a mass ratio of 1:1, cut into 3 cm small segments, and soaked in a sulfuric acid solution with a mass concentration of 33% for 48 hours. After being taken out, they are washed with deionized water to a pH of 7 to obtain acidified reed segments, and the acidified reed segments are dried in an oven at 58°C, and then crushed through 100 mesh. The acidified reed powder was sieved to obtain acidified reed powder, and the acidified reed powder was soaked in a Fe(NO3)3 solution with a molar concentration of 0.3, and the mass ratio of the acidified reed powder to the pure iron in the Fe(NO3)3 solution was adjusted to 21:1. After soaking for 12 hours, they were placed in a high-pressure reactor together, and kept warm at 250°C for 5 hours under the condition of continuous N2 flow. The solid-liquid mixture was taken out, washed with anhydrous ethanol and filtered to obtain a solid powder, and the solid powder was dried in an oven at 47°C to obtain biochar.

[0072] Note: In Examples 4 to 6, the proportion of soil conditioner is reasonably adjusted according to the amount of reeds harvested in the aquatic plant planting area 3. When more reeds are harvested, the amount of reeds can be appropriately increased, that is, the content of modified biochar is increased, but the modified biochar should not be too high, otherwise it will cause increased costs and waste of resources; at the same time, when preparing biochar, N2 is introduced at a flow rate of 100 mL / min for 30 minutes to keep the hydropyrolysis carbonization reaction process in an anaerobic state.

[0073] Example 7

[0074] The difference between this embodiment and embodiment 1 is that:

[0075] S3. The initial soil treatment is carried out in April, so that the water depth of the aquatic plant planting area 3 in each treatment unit is 40%, and then the soil conditioner is mixed into the terrestrial plant planting area 1, and the mixing amount is 60kg / mu;

[0076] S4, the time of plant planting is in April and May, and within 15 days after the completion of the initial soil treatment in S3, terrestrial plants are planted in the terrestrial plant planting area 1, alkali canopy is planted in the alkali canopy planting area 2, and aquatic plants are planted in the aquatic plant planting area 3. After 20 days, water is sequentially injected into the first drainage channel 11 of the upstreammost treatment unit in each treatment unit strip, so that the water depth of the aquatic plant planting area 3 in each treatment unit is 60%. The terrestrial plants are Siberian saltbush and salt claw, and the aquatic plants are reeds. The seed dosage of terrestrial plants, alkali canopy and aquatic plants during planting is 8kg / mu, and the plant distance between terrestrial plants and alkali canopy is maintained at 6cm;

[0077] S5. The soil strengthening treatment time is from June to September. Through local water replenishment and drainage combined with rainfall, the water depth of the aquatic plant planting area 3 in each treatment unit is maintained at 70%. From October to March of the following year, through local water replenishment and drainage combined with rainfall, the water depth of the aquatic plant planting area 3 in each treatment unit is maintained at 30%.

[0078] Note: In S3~S5, the month to start treatment should be reasonably selected according to the geographical location of the saline-alkali land. For example, in areas with warmer climates, treatment can be started earlier, and in areas with colder climates, treatment can be started later. In areas with higher precipitation throughout the year, treatment can also be started earlier to avoid the impact of precipitation on plant planting.

[0079] Example 8

[0080] The difference between this embodiment and embodiment 1 is that:

[0081] While S3 to S5 are being carried out, the collected salt water is discharged through the underground pipe 4. The diameter of the underground pipe 4 is 100 mm. The pipe body of the underground pipe 4 is provided with 0.5 mm micropores. The material of the underground pipe 4 is PVC or PE. The buried depth of the underground pipe 4 is 1 m. Filter material is laid on the top of the underground pipe 4. Both ends of each underground pipe 4 extend outside the treatment unit strips on both sides. A water pump is provided at one end of the underground pipe 4.

[0082] Example 9

[0083] The difference between this embodiment and embodiment 1 is that:

[0084] While S3 to S5 are being carried out, the collected salt water is discharged through the underground pipe 4. The diameter of the underground pipe 4 is 120 mm. The pipe body of the underground pipe 4 is provided with 1 mm micropores. The material of the underground pipe 4 is PVC or PE. The buried depth of the underground pipe 4 is 2 m. Filter material is laid on the top of the underground pipe 4. Both ends of each underground pipe 4 extend outside the treatment unit strips on both sides. A water pump is provided at one end of the underground pipe 4.

[0085] Note: In Examples 8 and 9, the position of the underground pipe 4 is adjusted according to factors such as the precipitation in the area. For example, in areas with high precipitation or a large area of ​​saline-alkali land, the laying depth of the underground pipe 4 is appropriately increased.

[0086] Experimental example

[0087] Next, we verify the feasibility of the method of the present invention by means of field experiments. We selected bare saline-alkali land in the retreat zone of inland lakes in the semi-arid plateau. Among them, after being arranged according to the S2 management unit, the terrestrial plant planting area 1 and the alkali canopy planting area 2 in each management unit together form an area of ​​3m*4m. The direction of the management unit is perpendicular to the local dominant wind direction (northwest wind). Fresh water is regularly irrigated during the seedling stage to ensure the water requirement for plant survival. After the vegetation cover is formed, the maintenance water consumption is gradually reduced, and the plants with excessive growth in the planting area are appropriately thinned and weeded in time.

[0088] At the same time, we conducted a horizontal comparison within multiple independent governance units. The specific comparison method is shown in Table 1.

[0089] Table 1 Configuration

[0090] Serial number Configuration T1 Suaeda salsa+Atriplex sibirica T2 Suaeda + salt claw T3 Suaeda salsa+Atriplex sibirica+Achnatherum splendens T4 Suaeda salsa + Atriplex sibirica + Salicornia crusgalli + Cyperus rotundus + Achnatherum splendens T5 Suaeda salsa + Atriplex sibirica + desulfurized gypsum or sheep manure or biochar T6 Suaeda salsa + Atriplex sibirica + Achnatherum splendens + desulfurized gypsum or sheep manure or biochar T7 Example 1

[0091] Regularly investigate the coverage, quantity, and plant diversity of plants in the sample plots. At the same time, collect sample soil under different treatment measures, investigate the physical and chemical properties of the soil, and compare the differences in the physical and chemical properties of the soil under different restoration measures. Compare the restoration results, such as Figure 3 and Figure 4 As shown, when a variety of plants were planted in a mixed manner and desulfurized gypsum, sheep manure and biochar were applied in Example 1, the vegetation coverage was the highest, the plant diversity was the highest, and the soil pH value was the lowest, indicating that the method of the present invention can effectively improve the salinity of saline-alkali land, and can effectively improve the plant diversity of saline-alkali land after treatment.

[0092] like Figure 5 and Figure 6 As shown, it can also be seen from the comparison chart of the treatment results of Example 1 that after one year of treatment according to the method of Example 1, the plant species diversity in the saline-alkali land is significantly increased.

Claims

1. A method for improving saline-alkali soil in semi-arid areas to enhance plant diversity, characterized in that: The following steps are involved: S1. Construction of treatment units: the bare land to be treated is divided into a plurality of treatment units. In each treatment unit, from upstream to downstream, there are a terrestrial plant planting area (1), an alkali canopy planting area (2), and an aquatic plant planting area (3). A first drainage channel (11) is excavated on both sides and inside the terrestrial plant planting area (1), and a second drainage channel (21) is excavated on both sides and inside the alkali canopy planting area (2). The second drainage channel (21) is connected to the aquatic plant planting area (3); S2, arrangement of treatment units: a plurality of the treatment units are arranged in sequence in the longitudinal direction to form a treatment unit strip, and a plurality of the treatment unit strips are arranged in sequence in the transverse direction, and at the same time, the alkali canopy planting area (2) and the aquatic plant planting area (3) in two adjacent treatment unit strips are aligned with each other, and an underground concealed pipe (4) perpendicular to the treatment unit strip is laid below the alkali canopy planting area (2) and the aquatic plant planting area (3); S3. Preliminary soil treatment: In March to May, water is sequentially injected into the first drainage channel (11) of the upstreammost treatment unit in each treatment unit strip, so that the water depth of the aquatic plant planting area (3) in each treatment unit is not less than 40%, and then soil conditioner is mixed into the terrestrial plant planting area (1), and the mixing amount is 60-80 kg / mu; S4, plant planting: in March to May, and within 10 to 15 days after the completion of the initial soil treatment in S3, terrestrial plants are planted in the terrestrial plant planting area (1), alkali canopy is planted in the alkali canopy planting area (2), and aquatic plants are planted in the aquatic plant planting area (3). After 15 to 20 days, water is sequentially injected into the first drainage channel (11) of the upstreammost treatment unit in each treatment unit strip, so that the water depth in the aquatic plant planting area (3) in each treatment unit is not less than 60%; S5. Soil strengthening and management: from June to September, local water replenishment and drainage are combined with rainfall to maintain the water depth of the aquatic plant planting area (3) in each management unit at 60-70%. From October to March of the following year, local water replenishment and drainage are combined with rainfall to maintain the water depth of the aquatic plant planting area (3) in each management unit at 20-30%. While S3 to S5 are being carried out, the collected salt water is discharged through the underground concealed pipe (4).

2. The method for improving saline-alkali soil in semi-arid areas for improving plant diversity according to claim 1, characterized in that: In one of the treatment units, the first drainage channels (11) located on both sides and the second drainage channels (21) located on both sides are connected to each other, the number of the first drainage channels (11) inside the terrestrial plant planting area (1) is 2 to 4, the number of the second drainage channels (21) inside the alkali canopy planting area (2) is 3 to 6, and the first drainage channels (11) and the second drainage channels (21) are arranged crosswise.

3. The method for improving saline-alkali soil in semi-arid areas for improving plant diversity according to claim 1, characterized in that: The ratio of the areas of the terrestrial plant planting area (1), the alkali canopy planting area (2), and the aquatic plant planting area (3) is 1:1-1.5:2-3, and the depth of the aquatic plant planting area (3) is 30-40 cm.

4. The method for improving saline-alkali soil in semi-arid areas for improving plant diversity according to claim 1, characterized in that: Each of the governance unit stripes includes 5 to 20 governance units, and the number of governance unit strips is 3 to 10.

5. The method for improving saline-alkali soil in semi-arid areas for increasing plant diversity according to claim 1, characterized in that: The soil conditioner in S3 is a mixture of desulfurized gypsum, sheep manure and modified biochar in a mass ratio of 1:1:2-3.

6. The method for improving saline-alkali soil in semi-arid areas for increasing plant diversity according to claim 5, characterized in that: The preparation method of the biochar is as follows: the reeds in S5 are harvested as the biomass raw material of the biochar, the harvesting period is divided into two periods, the first period is the growing period of March to April, and the second period is the end of the maturity period, the reeds harvested twice are mixed in a mass ratio of 1:1, cut into 1-3 cm small segments, soaked in a sulfuric acid solution with a mass concentration of 30-40% for 48±1h, taken out and washed with deionized water to a pH of 7±0.2 to obtain acidified reed segments, the acidified reed segments are dried in an oven at 50-60°C, and then crushed to 100-1 20 mesh sieve to obtain acidified reed powder, soak the acidified reed powder in a Fe(NO3)3 solution with a molar concentration of 0.3-0.5, adjust the mass ratio of the acidified reed powder to the pure iron in the Fe(NO3)3 solution to 20-25:1, soak for 12 hours, put them into a high-pressure reactor together, keep them warm at 220-260°C for 4-6 hours under the condition of continuous N2 introduction, take out the solid-liquid mixture, wash it with anhydrous ethanol and filter it to obtain solid powder, dry the solid powder in an oven at 45-55°C to obtain biochar.

7. The method for improving saline-alkali soil in semi-arid areas for improving plant diversity according to claim 1, characterized in that: The terrestrial plants in S4 are one or more of Siberian canopy, salt claw, sedge, and Achnatherum splendens, and the aquatic plants are reeds. The seed dosage of terrestrial plants, alkali canopy, and aquatic plants during planting is 7-8 kg / mu, and the plant distance between terrestrial plants and alkali canopy is maintained at 5-6 cm.

8. The method for improving saline-alkali soil in semi-arid areas for increasing plant diversity according to claim 1, characterized in that: The underground pipe (4) has a diameter of 100 to 120 mm, the pipe body of the underground pipe (4) is provided with micropores of 0.5 to 1 mm, the material of the underground pipe (4) is PVC or PE, the buried depth of the underground pipe (4) is 1 to 2 m, and filter material is laid on the top of the underground pipe (4).

9. The method for improving saline-alkali soil in semi-arid areas for increasing plant diversity according to claim 1, characterized in that: Both ends of each underground concealed pipe (4) extend outside the treatment unit strips located on both sides, and a water pump is provided at one end of the underground concealed pipe (4).

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