A three-dimensional in-situ afforestation structure and method for coastal saline-alkali land

Abstract

The present invention provides a coastal saline-alkali land in-situ three-dimensional afforestation structure and method, including a planting hole and a trench, wherein the planting hole is provided with a salt-draining trench, an original soil buffer layer, a saltpeter layer, a planting soil layer, a soil fertilization layer, and a surface evaporation control and salt inhibition system from bottom to top, and a salt-isolating membrane is provided around the inner wall of the planting hole above the saltpeter layer; one end of the salt-draining trench is connected to the trench. The coastal saline-alkali land in-situ three-dimensional afforestation structure described in the present invention realizes the comprehensive regulation of water, salt, fertilizer, and soil in saline-alkali soil in coastal areas by combining soil replacement in tree hole micro-domains with engineering measures. It has the characteristics of low cost, simple preparation, and convenient application, can effectively reduce soil salinity and alkali obstacles, promote fertilization and soil improvement in coastal areas, and provide a good living environment for plants.

Description

Technical Field

[0001] The invention belongs to the technical field of afforestation, and in particular relates to an in-situ three-dimensional afforestation structure and method for coastal saline-alkali land. Background Art

[0002] As an important land resource, saline-alkali soil is widely distributed in the inland areas of Northeast my country, North China, Northwest China and the coastal areas north of the Yangtze River. At present, the area of ​​saline soil in my country is 520 million mu, and there are still about 260 million mu of potential salinized soil, and 86.5258 million mu have been reclaimed for planting. Carrying out saline-alkali soil ecological restoration work is of great significance to improving the fertility of saline farmland in my country, ensuring national food security and improving the ecological environment. Coastal saline-alkali soil is mainly distributed in the intertidal zone. Due to the influence of soil formation process and soil parent material, coastal saline-alkali soil has the characteristics of high salt content, poor physical structure, low soil fertility level, and strong seasonal water and salt movement, which seriously affects plant growth and even causes plant death. Therefore, coastal saline-alkali land management and afforestation is an extremely arduous task. At present, there has been no fundamental breakthrough in the technology of establishing native saline-alkali soil shelterbelts in coastal areas.

[0003] According to the characteristics and utilization purpose of coastal saline-alkali soil, corresponding engineering measures, farming measures and comprehensive measures can be taken to repair and utilize saline-alkali soil. The imported soil method is a commonly used measure in afforestation projects. It can quickly and effectively reduce the salt content of the soil by replacing all or part of the soil. However, the imported soil method requires a large amount of earthwork, and the source and transportation are problematic, so the production cost is relatively high. At present, the cost of the imported soil method in afforestation projects is 50-60 yuan / m3. At the same time, the imported soil method is also easy to damage farmland and soil salinization is easy to repeat, which is not sustainable. Therefore, it is of great significance to explore environmentally friendly and ecologically green in-situ soil desalination technology for the improvement and utilization of saline-alkali soil.

[0004] From the perspective of existing technologies, the technologies currently accumulated for in-situ afforestation of coastal saline-alkali lands are mainly carried out from engineering measures such as irrigation and salt washing, terraced fields-shallow pools / deep trenches for salt drainage, and concealed pipes for salt drainage. Although the existing tree-pit planting method is supplemented with soil fertilization technologies such as improvers, organic fertilizers or nutrient soil, due to the lack of effective soil salt isolation and salt inhibition measures, the saline-alkali stress to which plants are subjected gradually increases two years after planting, and even leads to plant death. The restoration and utilization of saline-alkali land is a systematic and integrated project. It is necessary to comprehensively consider multiple factors such as soil irrigation and drainage, water and salt regulation, fertilization and soil improvement, in order to achieve ecological restoration and efficient utilization of coastal saline-alkali land. Summary of the invention

[0005] In view of this, the present invention aims at the practical problems of serious soil salinity barrier and difficulty of plant survival in the process of afforestation and greening of saline-alkali land in coastal areas, and proposes a three-dimensional afforestation structure and method for in-situ saline-alkali land in coastal areas. By combining soil replacement in tree pit micro-domains with engineering measures, the comprehensive regulation of water, salt, fertilizer and soil in saline-alkali soil in coastal areas is achieved. It has the characteristics of low cost, simple preparation and convenient application, can effectively reduce soil salinity barrier, promote fertilization and soil improvement in coastal areas, provide a good living environment for plants, and ensure the survival rate of selected seedlings is above 90%.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] A three-dimensional in-situ afforestation structure for coastal saline-alkali land comprises a planting hole and a trench, wherein a salt-draining trench, an original soil buffer layer, a saltpeter layer, a planting soil layer, a soil fertilization layer and a surface evaporation control and salt inhibition system are arranged in the planting hole from bottom to top, and a salt-isolating membrane is arranged above the saltpeter layer and around the inner wall of the planting hole; one end of the salt-draining trench is connected to the trench.

[0008] Among them, the trench and salt drainage ditch constitute the regional groundwater level control system. The trench is used to drain the salt leached from the upper soil in the planting hole, and the original soil buffer layer plays a buffering role between the salt drainage ditch and the upper structure to avoid excessive loss of water in the upper soil.

[0009] The saltpeter layer and salt-isolating film constitute the salt drainage system of the planting holes. The saltpeter layer can promote the downward leaching of soil salt in the holes, cut off the capillary action of the soil, and block the return of soil salt. The salt-isolating film can isolate the lateral return of soil salt, effectively reducing the harm of seasonal water and salt migration in the soil to plant growth.

[0010] The soil fertilization layer constitutes the soil fertilization system of the planting hole.

[0011] The surface evaporation control and salt suppression system can suppress surface evaporation and prevent soil salt return.

[0012] Furthermore, the slope of the salt drainage ditch towards the rough ditch is 3‰, ensuring that the salt washed from the upper soil to the salt drainage ditch can smoothly enter the rough ditch.

[0013] Furthermore, the salt-draining ditch is filled with saltpeter, and non-woven fabrics are provided between the salt-draining ditch and the filled saltpeter and on the upper surface of the filled saltpeter.

[0014] Among them, the specification of non-woven fabric can be 20g / m 2 The non-woven fabric can be laid in a "U" shape in the salt drainage ditch, and then saltpeter can be filled into the salt drainage ditch.

[0015] Furthermore, one end of the salt drainage ditch is connected to the rough ditch via a blind pipe, and the length of the blind pipe can be selected according to actual conditions.

[0016] Furthermore, non-woven fabric is provided between the saltpeter layer and the original soil buffer layer, and between the saltpeter layer and the planting soil.

[0017] Furthermore, the soil fertilization layer includes a soil conditioner and planting soil, and the soil conditioner includes the following components in mass percentage: superphosphate 7% to 8%, fulvic acid 1% to 4%, furfural residue 8% to 10%, and earthworm manure 75% to 85%, and the sum of the mass percentages of each component is 100%.

[0018] Prepare soil conditioner according to the above components based on actual conditions, then stir and evenly mix the soil conditioner and planting soil according to actual usage, and backfill them into the planting hole to form a soil fertilization layer.

[0019] Furthermore, the surface evaporation control and salt inhibition system is a plastic film covering the surface of the planting hole.

[0020] Furthermore, the depth of the salt drainage ditch is 0.15m, the thickness of the original soil buffer layer is 0.2m, the thickness of the saltpeter layer is 0.1m, the thickness of the planting soil layer is 0.35m, and the thickness of the soil fertilization layer is 0.3m.

[0021] The present invention also includes a method for in-situ three-dimensional afforestation of coastal saline-alkali land, comprising the following steps:

[0022] (1) Positioning;

[0023] (2) Excavation of planting troughs and salt drainage ditch: After excavating the planting troughs, dig a salt drainage ditch along the center of the trough bottom. The salt drainage ditch has a certain slope;

[0024] (3) Digging a rough ditch, connecting the rough ditch with the salt drainage ditch through a blind pipe, and the salt drainage ditch is inclined downward toward the rough ditch;

[0025] (4) Laying and backfilling of salt drainage ditch: Lay non-woven fabric in the salt drainage ditch and backfill with saltpeter. One end of the blind pipe is buried in the saltpeter and the other end is extended to connect with the trench. Lay non-woven fabric on the backfilled saltpeter and backfill with original soil until it is flush with the original soil surface.

[0026] (5) Tree pit positioning and tree pit salt isolation system laying: After the tree pit is positioned, the tree pit is excavated, and a saltpeter layer is laid at the bottom of the tree pit. Non-woven fabrics are laid on the upper and lower surfaces of the saltpeter layer, and a salt isolation film is laid on the inner wall of the tree pit. Then, a certain thickness of planting soil is backfilled into the tree pit;

[0027] (6) soil fertilization: filling the tree hole with a mixed soil conditioner and planting soil, and leveling the land; the soil conditioner comprises the following components by mass percentage: superphosphate 7% to 8%, fulvic acid 1% to 4%, furfural residue 8% to 10%, and earthworm manure 75% to 85%, and the sum of the mass percentages of the components is 100%;

[0028] (7) Surface evaporation control and salt suppression: After planting in the tree holes, cover the entire row of tree holes on the surface to suppress surface evaporation and prevent soil salt from returning.

[0029] Furthermore, in step (2), the depth of the salt drainage ditch is 0.15m and the width is 0.25m; in step (3), the slope of the salt drainage ditch toward the ditch is 3‰; in step (5), the thickness of the saltpeter layer is 0.1m, the vertical distance from the bottom of the saltpeter layer to the salt drainage ditch is 0.2m, and the thickness of the planting soil is 0.35m; in step (6), the thickness of the mixed soil conditioner and planting soil filled in the tree hole is 0.3m; in step (7), the surface evaporation of the entire row of tree holes is suppressed by covering the surface, specifically, with the planted plants in the tree hole as the center, and plastic film is laid in strips on both sides.

[0030] Compared with the prior art, the in-situ three-dimensional afforestation structure and method for coastal saline-alkali land described in the present invention have the following advantages:

[0031] (1) The in-situ three-dimensional afforestation structure and method of coastal saline-alkali land of the present invention realizes the greening of saline-alkali land through the composite improvement of tree hole micro-area grooving. The three-dimensional afforestation technology that combines the bottom grooving with the soil replacement of the planting hole micro-area effectively reduces the amount of earthwork required for the greening project, achieving the purpose of cost saving and efficient management of saline-alkali land.

[0032] (2) The in-situ three-dimensional afforestation structure and method for coastal saline-alkali land described in the present invention achieves soil water and salt regulation through comprehensive measures of planting holes. Based on the combined regulation of salt isolation in the hole, drainage under the hole and surface film covering, the upward movement of soil water and salt is effectively prevented and controlled, and the salt leached from the upper layer is discharged from the soil in time, providing a good water and salt environment for plant growth and ensuring the survival rate of plants.

[0033] (3) The in-situ three-dimensional afforestation structure and method for coastal saline-alkali land described in the present invention can achieve multiple goals of reducing saline-alkali obstacles, fertilizing the soil, and synergizing greening. In the saline-alkali land afforestation project, factors such as water, salt, fertilizer, and soil are considered as a whole for overall planning, and a set of coastal saline-alkali land afforestation optimization operation technology including surface evaporation and salt suppression, groundwater level control, planting hole salt drainage, and soil fertilization is proposed to achieve the synergistic effect of water and salt regulation, fertilization and soil improvement, and greening and afforestation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0035] Figure 1 This is a schematic structural diagram of the in-situ three-dimensional afforestation structure for coastal saline-alkali land described in Example 1;

[0036] Figure 2 It is a structural schematic diagram of another direction of the in-situ three-dimensional afforestation structure of coastal saline-alkali land described in Example 1;

[0037] Figure 3 To test the rationality of the composition and dosage of soil conditioners, the effects of soil conditioners on soil desalination rate at different fulvic acid application rates were described in the part;

[0038] Figure 4 To test the rationality of the composition and dosage of soil conditioners, the effects of soil conditioners on soil desalination rate at different earthworm casting application rates are described in the section.

[0039] Description of reference numerals:

[0040] 1-planting hole; 2-grooves; 3-salt drainage ditch; 4-original soil buffer layer; 5-saltite layer; 6-planting soil layer; 7-soil fertilization layer; 8-surface evaporation control and salt inhibition system; 9-salt isolation membrane; 10-blind pipe. DETAILED DESCRIPTION

[0041] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0042] The present invention will be described in detail below with reference to the embodiments and the accompanying drawings.

[0043] Example 1

[0044] like Figure 1 and 2 As shown, a three-dimensional in-situ afforestation structure for coastal saline-alkali land includes a planting hole 1 and a trench 2. The planting hole 1 is provided with a salt drainage trench 3, an original soil buffer layer 4, a saltpeter layer 5, a planting soil layer 6, a soil fertilization layer 7 and a surface evaporation control and salt inhibition system 8 from bottom to top;

[0045] The salt drainage ditch 3 is 0.15m deep and 0.25m wide. It is set along the center of the bottom of the planting hole 1. The slope of the salt drainage ditch 3 to the ditch 2 is 3‰ to ensure that the salt leached from the upper soil to the salt drainage ditch 3 can be smoothly discharged into the ditch 2. The salt drainage ditch 3 is filled with saltpeter. Non-woven fabrics are laid between the salt drainage ditch 3 and the saltpeter filled and on the upper surface of the saltpeter filled. The specification of the non-woven fabrics is 20g / m 2 The salt drainage ditch 3 and the ditch 2 are connected by a blind pipe 10. The diameter of the blind pipe 10 is about 6 cm and the length is 1 to 1.5 m. One end of the blind pipe 10 is inserted into the saltpeter of the salt drainage ditch 3, and the other end extends into the ditch 2. The length of the ditch 2 is about 0.5 m. The ditch 2 is an inverted trapezoid, with a lower width of 0.75 m, an upper width of 2.3 m at the original soil surface, and a depth of 1.3 m. It is used to discharge the salt leached from the upper soil. A 20 cm thick original soil buffer layer 4 is provided above the salt drainage ditch 3. The original soil buffer layer 4 plays a buffering role between the salt drainage ditch 3 and the upper structure of the original soil buffer layer 4 (which can be called the tree hole part) to avoid excessive loss of moisture in the upper soil.

[0046] The saltpeter layer 5 is arranged on the original soil buffer layer 4. The thickness of the saltpeter layer 5 is 0.1m. The upper and lower surfaces of the saltpeter layer 5 are covered with non-woven fabrics. The specification of the non-woven fabric is 20g / m 2 The saltpeter layer 5 can promote the downward leaching of soil salt in the tree hole, cut off the capillary action of the soil, and block the return of soil salt. The inner wall of the tree hole is provided with a salt-isolating film 9, which can be a plastic film to isolate the lateral return of soil salt, effectively reducing the harm of seasonal water and salt migration in the soil to plant growth; a planting soil layer 6 with a thickness of 0.35m is provided on the saltpeter layer 5.

[0047] The soil fertilization layer 7 is formed by mixing soil conditioner and planting soil and filling them on the planting soil layer 6. The soil conditioner can be calculated according to the volume of the tree hole to be filled. For example, the volume of the tree hole to be filled is 0.18m 3 , then use 6kg of soil conditioner, and the rest is planting soil, mix well and fill it into the tree hole planting soil layer 6 until it is flush with the original soil. The soil conditioner includes the following components by mass percentage: superphosphate 7% to 8%, fulvic acid 1% to 4%, furfural residue 8% to 10%, earthworm manure 75% to 85%, and the sum of the mass percentages of each component is 100%.

[0048] The surface evaporation control and salt inhibition system 8 is a plastic film covering the surface of the planting holes 1. After the planting in the tree holes is completed, the entire row of tree holes is centered on the plant planted in the tree holes and plastic film is laid in strips on both sides. The plastic film can be a black plastic film with a width of 60 cm.

[0049] Performance Testing

[0050] 1. Soil desalination rate and tree survival rate experiment

[0051] The coastal area of ​​Tianjin is a typical area for the development of coastal soil salinization in my country. The test site of the technology of the present invention is located in the third section of the green barrier construction project between Shuangcheng, Jinnan District, Tianjin. The average salt content of the soil in the test site is 8.61g / kg, which is a medium to severe saline-alkali soil. From March 2019 to December 2019, a small area test with a total area of ​​15 acres was carried out in the project test area, and the technical scheme (Example 2) of the present invention was compared with the traditional afforestation technology. The tree species planted in the test area and the control area are golden elms.

[0052] Example 2

[0053] (1) Positioning: Lay out the working roads, areas, ditches, and salt drainage ditches in the planned greening area to identify the exact locations of blind ditches and salt drainage ditches during the afforestation process.

[0054] (2) Excavation of planting troughs and salt drainage trenches: excavate planting troughs with a depth of 0.95m and a centerline spacing of 3m between adjacent planting troughs. Later, excavate salt drainage trenches with a depth of 0.15m and a width of 0.25m along the center of the bottom of the planting trough. The salt drainage trench has a certain slope.

[0055] (3) Excavation of trench: The trench is in the shape of an inverted trapezoid, with a bottom width of 0.75m, a top height of 2.3m at the original soil surface, and a depth of 1.3m. The trench is connected to the salt drainage ditch by a blind pipe 1.5-2.0m long, and the slope of the salt drainage ditch towards the trench is 3‰;

[0056] (4) Laying and backfilling of salt drainage ditch: Lay non-woven fabric in a "U" shape in the salt drainage ditch. The specification of non-woven fabric is 20g / m 2 , and backfill with 0.15m thick saltpeter, one end of the blind pipe is buried in the saltpeter, and the other end is extended to connect with the trench, non-woven fabric is laid on the backfilled saltpeter, and then the original soil is backfilled to the same level as the original soil surface;

[0057] (5) Tree pit positioning and tree pit salt isolation system laying: After land preparation, the tree pits were laid out in 3m×3m rows and the experimental plots were marked. After the tree pits were positioned, a tree pit with a width of 0.8m and a depth of 0.65m was excavated. A 0.1m thick saltpeter layer was laid at the bottom of the tree pit. Non-woven fabric (specification: 20g / m 2 ), lay salt-isolating membrane on the inner wall of the tree hole, and then backfill the tree hole with 0.35m thick planting soil;

[0058] (6) Soil fertilization: Each tree hole (0.18m 36 kg of soil conditioner was applied, which was first mixed with the planting soil and then filled into the tree hole, and the land was leveled; the soil conditioner included the following components by mass percentage: superphosphate 8%, fulvic acid 3%, furfural residue 9%, and earthworm manure 80%;

[0059] (7) Planting of seedlings: Plant golden elm with a breast diameter of about 5 cm. After transplanting, use gate-shaped supports or triangular supports to further reinforce the trees. Use planting soil to build a water circle and then water and maintain the trees;

[0060] (8) Surface evaporation control and salt suppression: After planting, use 60 cm wide plastic film to cover the surface of the entire row of tree holes with the tree holes as the center, and lay one layer on each side in strips.

[0061] (9) Monitoring of plant growth process: including tree survival rate statistics and changes in soil salinity at different levels.

[0062] The test results of the technical solution of the present invention (Example 2) were compared and analyzed with the results of conventional afforestation technologies such as mixing cow dung with mountain sand, salt isolation of tree holes (saltpeter layer + salt isolation film), and drainage of saltpeter leaching layer under tree holes. The results are shown in Tables 1 and 2.

[0063] Table 1 Desalination rate of 0-60cm soil under different technical solutions

[0064]

[0065] Table 1 shows the desalination rate of 0-60cm soil under different technical solutions. It can be seen that compared with the conventional technical solution, the overall desalination of 0-60cm soil can reach 75.69% by adopting the technical solution of the present invention, thereby ensuring that the root activity range of golden elm is in a good habitat. Further analysis shows that compared with other technical solutions, the salinity of 0-20cm, 20-40cm, and 40-60cm soils is significantly reduced under the measures of this technical solution, and the soil desalination rates are 78.67%, 80.87% and 67.52% respectively.

[0066] Table 2 Statistics of survival rate of golden elm under different technical solutions

[0067]

[0068]

[0069] It can be seen from Table 2 that the survival rate of golden elm in the test area using this technical solution can reach 98.12%.

[0070] 2. Test on rationality of soil conditioner components and dosage

[0071] In order to illustrate the rationality of the components and dosage of the soil conditioner for planting holes in this technical solution, the core ingredients of the conditioner, fulvic acid and earthworm manure, were selected for dosage gradient tests. The test is located in the third section of the green barrier construction project between Shuangcheng, Jinnan District, Tianjin. The average salt content of the soil in the test site is 8.61g / kg, which is a medium to severe saline-alkali soil. From March 2019 to December 2019, a small plot test with a total area of ​​5,400m2 was carried out in the project test area to compare the regulatory effects and optimal dosage of adding fulvic acid and earthworm manure on soil salinity and alkali disorders. The tree species planted in the test area is golden elm.

[0072] The main implementation links are as follows (no salt drainage ditch, rough ditch and surface evaporation control and salt suppression system are set up):

[0073] (1) Positioning: Lay out the operation paths, areas, ditches, and salt drainage ditches in the planned greening area to identify the exact locations of blind ditches during the afforestation process.

[0074] (2) Digging planting trenches: Dig planting trenches with a depth of 0.95 m and a centerline spacing of 3 m between adjacent planting trenches;

[0075] (3) Tree pit positioning and tree pit salt isolation system laying: After land preparation, the tree pits were laid out in 3m×3m rows and the experimental plots were marked. After the tree pits were positioned, a tree pit with a width of 0.8m and a depth of 0.65m was excavated. A 0.1m thick saltpeter layer was laid at the bottom of the tree pit. Non-woven fabric (specification: 20g / m 2 ), lay salt-isolating membrane on the inner wall of the tree hole, and then backfill the tree hole with 0.35m thick planting soil;

[0076] (4) Soil fertilization: Each tree hole (0.18m 3 1. Apply 6kg of soil conditioner, mix the soil conditioner with the planting soil and then fill the tree hole, and level the land;

[0077] a. Under the same conditions as in Example 2, the application amount of superphosphate, furfural residue and earthworm castings in the soil conditioner was set to 80, 160 and 320 g / tree hole, and the corresponding mass percentages were 1.8%, 3.5% and 6.8%, respectively;

[0078] b. Under the condition that the application amount of superphosphate, furfural residue and fulvic acid in the soil conditioner (same as in Example 1) remains unchanged, the application gradient of earthworm castings is set to 0, 0.0025, 0.005, 0.0075 and 0.01m 3 / tree hole, that is, 0, 1.67, 3.34, 5.00, 6.67 kg / tree hole, and the corresponding mass percentages are 0%, 58%, 73%, 81%, 85% respectively.

[0079] (5) Planting of seedlings: Plant golden elm with a breast diameter of about 5 cm. After transplanting, use gate-shaped supports or triangular supports to further reinforce the trees. Use planting soil to build a water circle and then water and maintain the trees;

[0080] (6) Monitoring of plant growth process: changes in soil salinity at different levels.

[0081] In the practice of saline-alkali soil remediation, the soil desalination rate at 0-60 cm is an important indicator for measuring the salt reduction effect of soil conditioners. The higher the soil desalination rate from the surface to the deep layer, the more significant the salt reduction effect of the conditioner.

[0082] The test results show that: Figure 3 It can be seen that when the application rate of fulvic acid is 80-160g / tree hole, the salt content of the surface soil can be reduced to below 2‰, and the desalination effect of the 0-20cm, 20-40cm, and 40-60cm soil is significant.

[0083] Depend on Figure 4 It can be seen that compared with the control, the application of earthworm manure can effectively promote soil desalination, and the salt content of soil at different layers can be reduced to below 4‰, and the desalination effect of 0-20cm soil is the most significant. Among them, the application rate of earthworm manure is 0.0075m 3 / tree hole, it has a good regulating effect on the soil structure of 0-60cm, and the desalination rates of 0-20cm, 20-40cm, and 40-60cm soil are 51.03%, 62.71%, and 41.34% respectively. In engineering practice, with the increase of application amount, earthworm manure helps to leach salt into the deep soil, improve the overall desalination effect of the soil, and gradually enhance the fertilization and improvement effect of saline-alkali soil. However, considering the limitation of engineering cost, the application amount of earthworm manure should not be less than 0.0075m 3 / The tree hole should be located on the left or right side.

[0084] In summary, fulvic acid and earthworm castings, the core components of soil conditioners in the tree pit fertilization system, have good effects in regulating soil salinity and alkali. The optimal application amount is fulvic acid: 80-160g / tree pit, and earthworm castings should not be less than 0.0075m3 / tree pit (5kg / tree pit). The mass percentages in the soil conditioner are: fulvic acid 1-4%, earthworm castings 80%.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for in-situ three-dimensional afforestation of coastal saline-alkali land, characterized in that: The following steps are involved: (1) Positioning; (2) Excavation of planting troughs and salt drainage ditch: After excavating the planting troughs, dig a salt drainage ditch along the center of the trough bottom. The salt drainage ditch has a certain slope; (3) Digging a rough ditch, connecting the rough ditch with the salt drainage ditch through a blind pipe, and the salt drainage ditch is inclined downward toward the rough ditch; (4) Laying and backfilling of salt drainage ditch: Lay non-woven fabric in the salt drainage ditch and backfill with saltpeter. One end of the blind pipe is buried in the saltpeter and the other end is extended to connect with the trench. Lay non-woven fabric on the backfilled saltpeter and backfill with original soil until it is flush with the original soil surface. (5) Tree pit positioning and tree pit salt isolation system laying: After the tree pit is positioned, the tree pit is excavated, and a saltpeter layer is laid at the bottom of the tree pit. Non-woven fabrics are laid on the upper and lower surfaces of the saltpeter layer, and a salt isolation film is laid on the inner wall of the tree pit. Then, a certain thickness of planting soil is backfilled into the tree pit; (6) soil fertilization: filling the tree hole with a mixed soil conditioner and planting soil, and leveling the land; the soil conditioner comprises the following components by mass percentage: 8% superphosphate, 3% fulvic acid, 9% furfural residue, and 80% earthworm manure, and the sum of the mass percentages of the components is 100%; (7) Surface evaporation control and salt suppression: After the trees are planted in the pits, the entire row of pits is covered on the surface to suppress surface evaporation and prevent soil salt from returning; In step (2), the depth of the salt drainage ditch is 0.15m and the width is 0.25m; in step (3), the slope of the salt drainage ditch towards the rough ditch is 3‰; in step (5), the thickness of the saltpeter layer is 0.1m, the vertical distance from the bottom of the saltpeter layer to the salt drainage ditch is 0.2m, and the thickness of the planting soil is 0.35m; in step (6), the thickness of the mixed soil conditioner and planting soil filled in the tree pit is 0.3m; in step (7), the surface evaporation of the entire row of tree pits is suppressed by covering the surface, specifically, a plastic film is laid in strips on both sides with the plant planted in the tree pit as the center.

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