Method for comprehensive improvement of coastal saline-alkali soil based on salt-tolerant superabsorbent resin

Abstract

The application discloses a comprehensive improvement method for coastal saline-alkali soil based on salt-tolerant superabsorbent resin, which comprises the following steps: (1) removing a 1.5m deep soil layer, laying grass support pads and gravel layers on the bottom to construct an isolation layer; (2) selecting specially designed water permeable bricks, filling the water permeable bricks with salt-tolerant superabsorbent resin to construct small salt isolation modules; (3) laying the small salt isolation modules on the isolation layer to construct a salt isolation layer; (4) wrapping the salt-tolerant superabsorbent spherical resin in a water-saturated state with pine needle soil, mixing the salt-tolerant superabsorbent spherical resin with leached saline-alkali soil, and backfilling the mixture to form a root water-retention layer above the salt isolation layer; and (5) preparing soil texture repair matrix blocks, mixing the soil texture repair matrix blocks with leached saline-alkali soil, and backfilling the mixture to construct a composite soil cultivation layer. The application can significantly improve the soil environment, improve the soil physical structure, and be beneficial to improving the agricultural productivity and the ecosystem function of the saline-alkali soil by constructing the salt isolation layer and the root water-retention layer and improving the structure of the soil cultivation layer.

Description

TECHNICAL FIELD

[0001] The present application relates to a comprehensive improvement method for coastal saline-alkali land based on salt-tolerant superabsorbent resin, belonging to the technical field of soil engineering improvement and ecological restoration. BACKGROUND

[0002] Due to the long-term influence of seawater (brackish water) intrusion, the soil salt content of coastal saline-alkali land remains high, resulting in heavy soil texture, significant decrease in air and water permeability, and low nutrient content, which severely restricts plant growth and land use. Traditional improvement methods such as leaching, especially in coastal saline-alkali areas, the scarcity of freshwater resources makes it difficult to implement the method of flooding with water, and unreasonable irrigation such as flooding irrigation raises the groundwater level, combined with the strong evaporation effect in coastal areas, further aggravating the accumulation of surface salt, causing secondary soil salinization. The application of chemical regulators may affect soil fertility and ecological balance, while the underground pipe salt drainage is affected by the heavy soil texture in coastal areas, and the soil water and salt drainage effect is poor, which cannot effectively reduce the groundwater level.

[0003] Soil water and salt management is the core of coastal saline-alkali land management. The most important thing is to control the groundwater level, block the soluble salt in the groundwater from rising to the surface and accumulating, which can provide protection for soil structure restoration. Secondly, soil texture improvement is an important measure for the management of coastal saline-alkali land. Soil texture and structure have a great influence on water and salt migration. The finer the soil particles, the higher the capillary pore rising height and speed, and the easier the soil salinization.

[0004] Water-absorbing macromolecular polymers, such as polyacrylamide and water-absorbing resin, have shown great potential in agriculture and soil improvement due to their high water absorption and retention capacity. This material can absorb and retain a large amount of water while reducing water evaporation and loss, playing a key role in soil water retention and improving plant survival rate in arid and semi-arid areas. Using the excellent water absorption and retention of this material has important significance for water and salt management and soil improvement of saline-alkali land. However, the water absorption capacity of ordinary superabsorbent polymers will decrease significantly under high salt conditions, limiting their application in high salt environments. Therefore, salt-tolerant superabsorbent materials that can be widely used in coastal saline-alkali land are particularly important in the application of soil water and salt management and comprehensive improvement of soil texture. Not only can they improve water use efficiency and inhibit soil salt, but also can adjust soil physical structure, improve soil compaction, and promote the formation of soil aggregates, thereby providing favorable conditions for plant growth, significantly improving the agricultural productivity and ecological system function of saline-alkali land, and having important practical application value and prospect. SUMMARY

[0005] The application provides a comprehensive improvement method for coastal saline-alkali soil based on salt-tolerant superabsorbent resin, aiming at setting a salt isolation layer by using salt-tolerant superabsorbent resin to block the soil water and salt transport channel, continuously preventing salt accumulation on the ground surface, and applying the salt-tolerant superabsorbent resin to soil texture improvement, so that the soil hardening problem can be effectively solved, and water permeability and air permeability can be restored.

[0006] The application solves the above technical problems by adopting the technical scheme of a comprehensive improvement method for coastal saline-alkali soil based on superabsorbent resin, which comprises the following steps:

[0007] 1) demarcating a digging area, removing the soil layer with a depth of 1.5 m in the area, laying a straw cushion on the bottom with a thickness of 10 cm, laying a gravel layer on the straw cushion with a thickness of 15 cm, and forming an isolation layer at the bottom after leveling.

[0008] 2) selecting a water permeable brick with salt-tolerant superabsorbent resin in the water permeable brick to form a small salt isolation module.

[0009] 3) laying a 2 cm thick straw cushion on the isolation layer, laying the small salt isolation module on the straw cushion, connecting the salt isolation modules with biomass bricks to form a salt isolation layer.

[0010] 4) washing the removed saline-alkali soil with water until the soil salinity is reduced to below 1%, wrapping the salt-tolerant superabsorbent spherical resin in a pine needle soil in a saturated state, mixing the salt-tolerant superabsorbent spherical resin with the washed saline-alkali soil, and backfilling to form a root water retention layer above the salt isolation layer.

[0011] 5) cutting the prepared soil texture repair matrix into 1 cm 3 size matrix blocks, mixing the matrix blocks with the washed saline-alkali soil, and backfilling to form a composite soil cultivation layer.

[0012] Preferably, in step 1), the gravel layer is composed of gravel with a particle size of 50-80 mm and a thickness of 10 cm from bottom to top, and gravel with a particle size of 30-40 mm and a thickness of 5 cm.

[0013] Preferably, in step 2), the water permeable brick is a cement-based water permeable brick, which is in the shape of a triangular prism, hollow inside, and has a circular opening on the left and right sides of the brick body.

[0014] Preferably, in step 2), the size of the water permeable brick is that the bottom side length is 14 cm and the height is 20 cm.

[0015] Preferably, in step 2), the salt-tolerant superabsorbent resin selected is clay-based zwitterionic hydrophobic salt-tolerant superabsorbent resin spherical particles with a particle size of 5 mm.

[0016] Preferably, in step 2), the formation of the small salt barrier module involves filling the permeable brick with salt-resistant, highly absorbent resin particles through openings on both sides of the permeable brick, with each small salt barrier module using 45g of resin particles.

[0017] Preferably, in step 3), the salt barrier modules are laid in a straight line, and the edges of each row of salt barrier modules are aligned.

[0018] Preferably, in step 3), the size of the biomass bricks is consistent with that of the small salt-barrier module.

[0019] Preferably, in step 3), the small salt-barrier modules are connected by biomass bricks, which are filled in the space between the salt-barrier modules in an alternating manner, with each row of biomass bricks offset from each row of salt-barrier modules by half the length of a brick.

[0020] Preferably, in step 4), saturated salt-resistant superabsorbent spherical resin is mixed in the saline-alkali soil, with 10 saturated salt-resistant superabsorbent spherical resin particles added per cubic meter of soil.

[0021] Preferably, in step 4), the soil thickness of the root water-retaining layer is 40cm.

[0022] Preferably, in step 5), the components used to prepare the soil texture remediation matrix include: 15%–30% plant fiber; 35%–45% fermentation products of agricultural and forestry waste; 0.02%–0.05% soil binder; and 35%–45% fresh water.

[0023] The soil granulating agent is polyacrylamide.

[0024] Preferably, in step 5), soil texture remediation matrix blocks are mixed in saline-alkali soil at a volume ratio of 7:100.

[0025] The beneficial effects of this invention are:

[0026] In soil water and salt management, the use of salt-tolerant superabsorbent resin to establish a salt barrier effectively cuts off the channels for groundwater upwelling, reducing the transport of underground salts to the surface and thus significantly lowering the salt content of the topsoil. Furthermore, the salt-tolerant superabsorbent resin exhibits good chemical stability, enabling it to provide long-term soil improvement without negatively impacting the environment. Regarding soil texture improvement, introducing soil texture remediation matrix blocks into coastal saline-alkali land is beneficial for improving the soil's physical structure and permeability. The introduction of these blocks not only helps retain soil water but also promotes the formation of soil aggregates, while simultaneously improving soil aeration and permeability, creating more favorable conditions for plant root growth. Detailed Implementation

[0027] The following examples further illustrate the essence of the present invention, but the content of the present invention is not limited thereto.

[0028] The coastal saline-alkali land improvement area is located in the estuary saline soil zone of the lower reaches of the Dagu River in Qingdao, Shandong Province, with an experimental area of ​​100 square meters.

[0029] 1) Delineate a 100m area within the predetermined zone. 2 In the test area, the soil layer 1.5m deep was first excavated, and a 10cm thick grass support was laid at the bottom. Then, a 10cm thick layer of crushed stone with a particle size of 50-80mm and a 5cm thick layer of crushed stone with a particle size of 30-40mm were laid on top to complete the construction of the isolation layer.

[0030] 2) Select cement-based triangular prism permeable bricks, and fill each brick with 45g of salt-resistant, highly absorbent resin spherical particles (5mm in diameter) to make small salt-proof modules.

[0031] 3) Lay a 2cm thick straw mat on top of the isolation layer, and lay the small salt-barrier modules on it in a straight line, keeping the edges of each row of salt-barrier modules aligned; connect the salt-barrier modules with biomass bricks, and fill the spaces between the salt-barrier modules in an alternating pattern, with each row of biomass bricks offset from each row of salt-barrier modules by half a brick length, to complete the construction of the salt-barrier layer.

[0032] 4) Rinse the removed saline-alkali soil thoroughly with fresh water until the soil salinity drops below 1%; immerse the salt-tolerant superabsorbent resin spherical particles in clean water, take 400 saturated salt-tolerant superabsorbent resin spherical particles, wrap them with pine needle soil, mix them with the rinsed soil and backfill them, placing them above the salt barrier layer to form a 40cm thick root water retention layer.

[0033] 5) Take 0.18m of plant fiber 3 0.27m of fermentation products from agricultural and forestry waste 3 Soil binder 0.06m 3 Freshwater 0.24m 3 The components were thoroughly mixed to prepare a soil texture remediation matrix, which was then cut into 1cm pieces. 3 Soil texture restoration substrate blocks of various sizes are mixed with leached saline-alkali soil at a volume ratio of 7:100, backfilled and leveled to form a composite soil cultivation layer.

[0034] Soil salinity and physical properties were monitored regularly for six months after construction. Results showed that soil salinity decreased significantly at different depths, with the degree of salt accumulation decreasing with increasing soil depth. During the improvement period, the average salinity of the surface layer (0-20cm) in the experimental area was 9.33 g / kg, 9.23 g / kg, 8.89 g / kg, 8.26 g / kg, 7.65 g / kg, and 6.49 g / kg, respectively, a decrease of 2.84 g / kg; the average salinity of the deeper layer (40-80cm) was 6.21 g / kg, 5.87 g / kg, 5.43 g / kg, 5.12 g / kg, 5.10 g / kg, and 5.03 g / kg, respectively, a decrease of 1.18 g / kg. This indicates that soil salinity at each layer is significantly affected by the soil's structure and properties, demonstrating a significant improvement in soil permeability and water retention.

[0035] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A comprehensive improvement method for coastal saline-alkali land based on salt-resistant superabsorbent resin, characterized in that: include: 1) Delineate the excavation area, remove the soil layer 1.5m deep in the area, lay a straw mat at the bottom with a thickness of 10cm, and lay a layer of crushed stone with a thickness of 15cm on top of it. After leveling, form an isolation layer at the bottom. 2) Permeable bricks are selected. The permeable bricks are cement-based permeable bricks with a triangular prism shape and a hollow interior. The left and right sides of the brick are semi-closed and have circular openings. The permeable bricks contain salt-resistant and highly absorbent resin to form small salt-barrier modules. The process of making small salt-barrier modules is as follows: salt-resistant and highly absorbent resin spherical particles are filled into the permeable brick through the openings on the left and right sides of the permeable brick. The amount of resin particles used in each small salt-barrier module is 45g. 3) Lay a 2cm thick straw mat on top of the isolation layer, and lay the small salt-isolating modules flat on top of the straw mat. Connect the salt-isolating modules with biomass bricks to form a salt-isolating layer. The small salt-isolating modules are laid in a straight line, and the edges of each row of salt-isolating modules are aligned. Connect the small salt-isolating modules with biomass bricks, and fill the spaces between the salt-isolating modules in an alternating manner. The biomass bricks in each row are offset from each row of salt-isolating modules by half a brick length. 4) Rinse the removed saline-alkali soil with water until the soil salinity drops below 1%. Wrap the saturated salt-tolerant superabsorbent spherical resin with pine needle soil, mix it with the rinsed saline-alkali soil and backfill it, placing it above the salt barrier layer to form a root water-retaining layer. 5) Cut the prepared soil texture restoration substrate into 1cm3 substrate blocks, mix them with the leached saline-alkali soil in proportion, and backfill them. After leveling the surface, a composite soil cultivation layer is formed.

2. The comprehensive improvement method for coastal saline-alkali land based on salt-resistant superabsorbent resin according to claim 1, characterized in that: In step 2), the salt-resistant superabsorbent resin selected is clay-based zwitterionic hydrophobic salt-resistant superabsorbent resin spherical particles with a particle size of 5 mm.

3. The comprehensive improvement method for coastal saline-alkali land based on salt-resistant superabsorbent resin according to claim 1, characterized in that: In step 4), saturated salt-tolerant superabsorbent spherical resin is mixed in the saline-alkali soil, with 10 saturated salt-tolerant superabsorbent spherical resin particles added per cubic meter of soil.

4. The comprehensive improvement method for coastal saline-alkali land based on salt-resistant superabsorbent resin according to claim 1, characterized in that: In step 5), the components used to prepare the soil texture remediation matrix include: 15%–30% plant fiber; 35%–45% fermented agricultural and forestry waste products; 0.02%–0.05% soil binder; and 35%–45% fresh water.

5. The comprehensive improvement method for coastal saline-alkali land based on salt-resistant superabsorbent resin according to claim 1, characterized in that: In step 5), soil texture remediation matrix blocks are mixed in saline-alkali soil at a volume ratio of 7:100.