Water-saving and salt-inhibiting method and system for improving saline-alkali land in arid region

Abstract

The invention provides a water-saving salt-inhibiting method and system for improving saline-alkali soil in an arid region, and the method comprises the steps: improving a soil body of target saline-alkali soil, and obtaining a soil layer with soil particles smaller than a first particle threshold value and a gravel layer with soil particles larger than a second particle threshold value and smaller than a third particle threshold value; the underground water burial depth of the target saline-alkali soil is obtained, the thickness of the soil layer is set to be larger than a preset first thickness threshold value so that the improved soil layer can be located above the underground water burial depth, and the thickness of the gravel layer is set to be larger than a preset second thickness threshold value; after the soil body configuration structure comprising the improved soil layer and the gravel layer is completed, irrigation and salt leaching are carried out, so that the salinity of the soil layer is reduced to be smaller than a preset salinity threshold value; during each irrigation after crops are planted in the soil body configuration structure, the depth of an irrigated wetting front is not greater than the thickness of the soil layer. And the water-saving and salt-inhibiting efficiency can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of saline-alkali land improvement, and in particular to a water-saving and salt-inhibiting method and system for improving saline-alkali land in arid areas. Background Art

[0002] Food security is a top priority for the country, and improving the productivity of cultivated land is a fundamental measure to ensure food security. In the relatively closed inland western region, due to the lack of access to the sea, rainfall is relatively scarce, evaporation is intense, sandstorms are prevalent, and soil salt is difficult to remove out of the area. There are large areas of arid saline-alkali land with scarce water resources, high soil salt content but flat terrain. As the geological cycle proceeds, the soil salinity in these arid saline-alkali lands gradually increases. Therefore, one of the effective measures to improve the productivity of cultivated land is to effectively transform these areas and fully tap the comprehensive utilization potential of saline-alkali land. Summary of the invention

[0003] In view of this, the object of the present invention is to provide a water-saving and salt-inhibiting method and system for improving saline-alkali land in arid areas, so as to improve soil production efficiency.

[0004] In a first aspect, an embodiment of the present invention provides a method for improving saline-alkali land in arid areas by saving water and inhibiting salt, comprising: Improve the soil of the target saline-alkali land to obtain a soil layer with soil particles smaller than a first particle threshold and a gravel layer with soil particles larger than a second particle threshold but smaller than a third particle threshold; Obtaining the groundwater depth of the target saline-alkali land, setting the soil layer thickness to be greater than a preset first thickness threshold so that the improved soil layer is located above the groundwater depth, and setting the gravel layer thickness to be greater than a preset second thickness threshold; After the soil configuration structure including the improved soil layer and the gravel layer is completed, water is poured to wash away the salt so as to reduce the salinity of the soil layer to less than a preset salinity threshold; During each irrigation after planting crops in the soil configuration structure, the depth of the irrigation wetting front is no greater than the thickness of the soil layer.

[0005] In combination with the first aspect, an embodiment of the present invention provides a first possible implementation of the first aspect, wherein obtaining a soil layer in which soil particles are smaller than a first particle threshold and a gravel layer in which soil particles are larger than a second particle threshold and smaller than a third particle threshold comprises: The soil configuration characteristics of the target saline-alkali land are determined to be shallow effective soil layer and multi-layer texture mutation. The screening method based on the first threshold of particles is used to screen out gravel in the soil, turn the screened gravel to the lower part of the soil to form a gravel layer, and turn the screened fine soil material to the upper part of the gravel layer to form a soil layer. The soil configuration characteristics of the target saline-alkali land are determined to be deep soil with uniform texture, thick compacted layer and shallow burial depth. The soil is crushed and mixed, and gravel is obtained from other areas and turned to the bottom of the soil to form a gravel layer. Furthermore, the crushed and mixed soil is turned to the top of the gravel layer to form a soil layer.

[0006] In combination with the first aspect, the embodiment of the present invention provides a second possible implementation of the first aspect, wherein the step of irrigating with water to wash away salt to reduce the salinity of the soil layer to less than a preset salinity threshold value includes: The soil layer is irrigated until the soil is saturated or supersaturated, so that the saturated water or supersaturated water, driven by gravity, penetrates through the gravel layer and flows into the deep soil. The irrigation is stopped after the salinity of the soil layer is reduced to less than the preset salt threshold.

[0007] In combination with the first aspect, the first possible implementation manner of the first aspect, or the second possible implementation manner of the first aspect, the embodiment of the present invention provides a third possible implementation manner of the first aspect, wherein obtaining a soil layer having soil particles smaller than a first particle threshold comprises: The surface soil of the target saline-alkali land is transformed into a soil layer with more than 75% of soil particles less than 2mm and a depth greater than 50cm.

[0008] In combination with the first aspect and any possible implementation manner of the first aspect to the third possible implementation manner of the first aspect, the embodiment of the present invention provides a fourth possible implementation manner of the first aspect, wherein the method further includes: Every preset year, the salinity of the target saline-alkali land is tested before planting. When it is detected that the salinity exceeds the salinity threshold, water is re-irrigated to wash away the salt.

[0009] In combination with the first aspect, and any possible implementation manner from the first possible implementation manner to the third possible implementation manner of the first aspect, an embodiment of the present invention provides a fifth possible implementation manner of the first aspect, wherein the groundwater burial depth is greater than the sum of the thickness of the soil layer and the thickness of the gravel layer.

[0010] In combination with the first aspect, and any possible implementation manner from the first possible implementation manner to the third possible implementation manner of the first aspect, an embodiment of the present invention provides a sixth possible implementation manner of the first aspect, wherein the first threshold value of particles is 2 mm, the second threshold value of particles is 2 mm, and the third threshold value of particles is 250 mm.

[0011] In combination with the first aspect and any possible implementation manner from the first possible implementation manner to the third possible implementation manner of the first aspect, an embodiment of the present invention provides a seventh possible implementation manner of the first aspect, characterized in that the first thickness threshold is 100 cm, the second thickness threshold is 20 cm, and the salt threshold is 2.0 g / kg.

[0012] In combination with the first aspect and any possible implementation manner from the first possible implementation manner to the third possible implementation manner of the first aspect, an embodiment of the present invention provides an eighth possible implementation manner of the first aspect, characterized in that the preset period is 15 years.

[0013] In a second aspect, an embodiment of the present invention provides a water-saving and salt-inhibiting system for improving saline-alkali land in arid areas, comprising: a soil layer and a gravel layer, wherein: The soil layer is a soil layer whose soil particles are smaller than a first particle threshold, and is obtained by transforming the surface soil of the target saline-alkali land. The thickness of the soil layer is greater than a preset first thickness threshold, and the groundwater depth of the target saline-alkali land is below the soil layer; The gravel layer is located below the soil layer, and is used to transform the soil below the soil layer of the target saline-alkali land into a soil layer with soil particles larger than the second particle threshold and smaller than the third particle threshold, and the thickness of the gravel layer is greater than the preset second thickness threshold; Water is poured into the transformed soil layer to wash away the salt until the salinity of the soil layer is reduced to less than a preset salinity threshold; Crops are planted in the soil layer after the salt is washed off with water, and each time the crops are irrigated, the depth of the irrigation wetting front is not greater than the thickness of the soil layer.

[0014] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 A schematic flow chart of a method for improving saline-alkali land in arid areas provided by an embodiment of the present invention is shown; Figure 2 The schematic diagram of the structure of the water-saving and salt-inhibiting system for improving saline-alkali land in arid areas provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0018] In the related art, in the relatively closed inland western region, due to the lack of an outlet to the sea, rainfall is relatively scarce, evaporation is intense, and sandstorms are prevalent, the soil salt in the soil is difficult to discharge outside the domain. With the progress of the geological cycle, the soil salinity in the region gradually increases, and there are saline-alkali lands in arid areas with scarce water resources, high soil salt content but flat terrain. In these saline-alkali lands, the soil salt in the cultivated layer mainly comes from the deep soil of the geological cycle, and only a small part comes from aerial precipitation and irrigation. Therefore, it is not suitable to use the existing irrigation and leaching method. Even if there are conditions for the irrigation and leaching method, since the soil salt is reciprocating in the soil body, the soil salt cannot be discharged outside the domain. It can only create local low-salt spatial areas in stages, thereby consuming precious water resources, resulting in a worsening of the water shortage situation and reducing production efficiency. Therefore, it is the basis for improving the productivity of cultivated land to effectively transform these soil bodies, solve the problems of agricultural water conservation and soil salinity, and fully tap the comprehensive utilization potential of saline-alkali land.

[0019] Soil configuration has a significant impact on the cross-sectional movement of soil moisture and salt. Reasonable soil configuration can not only improve the salt discharge efficiency and inhibit the movement of salt to the root zone, but also reduce leakage, inhibit evaporation, conserve water and save water, thereby improving the productivity of cultivated land. Through soil sampling surveys of saline-alkali lands in the western arid region, it was found that the soil configuration of most saline-alkali lands in the western inland is: the soil texture is too deep and uniform, the effective soil layer is shallow, the compacted layer is thick and the burial depth is shallow, and the texture has multiple layers of mutations, which makes the water-saving and salt-inhibiting performance weak, which is not conducive to water-saving, soil moisture conservation and salt inhibition.

[0020] In this embodiment, a method for improving the salinity of saline-alkali land soil with low operating cost and long-term effect is proposed, which can permanently eliminate the hazards of soil salt, reduce the water consumption per unit of cultivated land, save water and inhibit salt. Specifically, according to a basic law of soil moisture physics: saturated water can freely pass between soils of different textures, while unsaturated water is difficult to enter coarse soil and gravel layers from fine soil. Therefore, using this principle, according to the soil configuration characteristics of saline-alkali land in the western arid area, a coarse particle layer that is much coarser than the upper soil layer is set at a certain depth of soil layer (soil layer below the tillage layer), forming an isolation layer of the upper soil layer, so that through soil transformation and appropriate irrigation methods, the salt can be leached out of the target soil at a certain depth, and the salt can be prevented from returning to the target soil, and the soil moisture can be prevented from leaking, thereby achieving water saving.

[0021] The embodiment of the present invention provides a method for saving water and inhibiting salt in improving saline-alkali land in arid areas, which is described below through examples.

[0022] Figure 1 The schematic diagram of the process of the water-saving and salt-inhibiting method for improving saline-alkali land in arid areas provided by the embodiment of the present invention is shown. Figure 1 As shown, the process includes: S101, improving the soil of the target saline-alkali land to obtain a soil layer with soil particles smaller than a first particle threshold and a gravel layer with soil particles larger than a second particle threshold and smaller than a third particle threshold; In this embodiment, as an optional embodiment, the first particle threshold is 2 mm, the second particle threshold is 2 mm, and the third particle threshold is 250 mm, wherein the first particle threshold and the second particle threshold may be equal or unequal. In this embodiment, the second particle threshold is 5 mm to form a mutation at the contact interface between the soil layer and the gravel layer.

[0023] In this embodiment, as an optional embodiment, the soil texture in the improved soil layer includes but is not limited to: loamy sand, sandy loam, loam, and clay loam.

[0024] In this embodiment, as an optional embodiment, obtaining a soil layer in which soil particles are smaller than a first particle threshold includes: The surface soil of the target saline-alkali land is transformed into a soil layer with more than 75% of soil particles less than 2mm and a depth greater than 50cm.

[0025] In this embodiment, as an optional embodiment, obtaining a soil layer in which soil particles are smaller than a first particle threshold and a gravel layer in which soil particles are larger than a second particle threshold and smaller than a third particle threshold includes: The soil configuration characteristics of the target saline-alkali land are determined to be shallow effective soil layer and multi-layer mutation of texture. The screening method based on the first threshold of particles is adopted to screen out gravel in the soil based on the interphase filling method, and the screened gravel is turned to the lower part of the soil to form a gravel layer, and the screened fine soil material is turned to the upper part of the gravel layer to form a soil layer. The soil configuration characteristics of the target saline-alkali land are determined to be uniform and thick in texture, thick in compaction layer and shallow in burial depth. The soil is crushed and mixed, and gravel is obtained from other areas and turned over to the bottom of the soil to form a gravel layer. Furthermore, the crushed and mixed soil is turned over to the top of the gravel layer to form a soil layer.

[0026] In this embodiment, as an optional embodiment, the coarse particle material in the gravel layer includes but is not limited to: rock or mineral debris.

[0027] S102, obtaining the groundwater depth of the target saline-alkali land, setting the soil layer thickness to be greater than a preset first thickness threshold so that the improved soil layer is located above the groundwater depth, and setting the gravel layer thickness to be greater than a preset second thickness threshold; In this embodiment, as an optional embodiment, the first thickness threshold is 50 cm, and as another optional embodiment, the first thickness threshold is 100 cm. In this way, for saline-alkali land in arid areas, it can be ensured that the groundwater depth of the saline-alkali land is below the soil layer.

[0028] In this embodiment, as an optional embodiment, the second thickness threshold is greater than or equal to 20 cm.

[0029] In this embodiment, as an optional embodiment, the salt threshold is 2.0 g / kg.

[0030] In this embodiment, as an optional embodiment, the groundwater depth is greater than the soil layer thickness. As another optional embodiment, the groundwater depth is greater than the sum of the soil layer thickness and the gravel layer thickness.

[0031] In this embodiment, for saline-alkali land in arid areas where the soil texture is too deep and uniform, the effective soil layer is shallow, the compacted layer is thick and the burial depth is shallow, and the texture has multiple layers of mutation, in order to form a significant texture mutation with the upper soil layer and prevent the upper soil layer from being supported by water and forming stagnant water, as an optional embodiment, the coarse particles in the gravel layer are set to have a particle size greater than 2mm and less than 250mm, and the thickness of the gravel layer is greater than or equal to 20cm.

[0032] In this embodiment, as an optional embodiment, through engineering measures, the soil at a depth of 1 meter and below is transformed into a coarse-gravel layer with a particle size of ≥ 2 mm; the soil above a depth of 1 meter is transformed into a soil texture finer than sand, such as loamy sand, sandy loam, loam, clay loam, etc. As an optional embodiment, the improved soil configuration is specifically as follows: The thickness of the upper fine soil layer (soil layer) is ≥50cm, with the optimal thickness being around 100cm; at the same time, more than 75% of the soil particles are less than 2mm in size.

[0033] The material of the lower coarse-grained soil layer (gravel layer) is rock or mineral debris, with a particle size of >2mm and <250mm; thickness ≥20cm.

[0034] S103, after the soil configuration structure including the improved soil layer and the gravel layer is completed, water is poured to wash away the salt, so as to reduce the salinity of the soil layer to less than a preset salinity threshold; In this embodiment, as an optional embodiment, watering and salt removal are performed to reduce the salinity of the soil layer to less than a preset salinity threshold, including: The soil layer is irrigated until the soil is saturated or supersaturated, so that the saturated water or supersaturated water, driven by gravity, penetrates through the gravel layer and flows into the deep soil. The irrigation is stopped after the salinity of the soil layer is reduced to less than the preset salt threshold.

[0035] S104, during each irrigation after the crops are planted in the soil configuration structure, the depth of the irrigation wetting front is not greater than the thickness of the soil layer.

[0036] In this embodiment, as an optional embodiment, in the first year after the soil body configuration structure is formed, 1 to 2 irrigations are performed to wash away the salt, so as to reduce the salt content of the upper soil layer to less than 2.0 g / kg. After planting crops, the depth of the wetting front is less than or equal to the thickness of the upper soil layer during each irrigation. That is, except for the irrigation for washing away the salt, when irrigation is performed during the planting process, the depth of the wetting front of a single irrigation cannot be greater than the depth of the soil layer.

[0037] In this embodiment, as an optional embodiment, the method further includes: Every preset year, the salinity of the target saline-alkali land is tested before planting. When it is detected that the salinity exceeds the salinity threshold, water is re-irrigated to wash away the salt.

[0038] In this embodiment, as an optional embodiment, after the operation of the soil configuration structure exceeds the preset service life threshold, water is re-irrigated to wash out the salt, wherein the service life threshold can be between 15 and 24 years. As an optional embodiment, since the method of this embodiment can effectively prevent the salt back-salination of deep soil, the salt accumulation in the soil mainly comes from aerial sedimentation and irrigation. Therefore, after the soil layer is washed out, the salt content remains relatively stable, and the preset service life can be set to 5 to 6 years.

[0039] In this embodiment, in the first year after the soil configuration structure is built, 1-2 irrigations are performed to wash away the salt, so as to reduce the salt content of the upper soil layer to below 2.0 g / kg. Thereafter, in order to prevent the soil layer and the gravel layer from establishing water connection, the depth of the wetting front is ≤ the thickness of the upper soil layer during each irrigation. After the target saline-alkali land has been in operation for many years (generally between 15 and 24 years), another irrigation is performed to wash away the salt.

[0040] The method of this embodiment can be effectively used in arid saline-alkali areas where the groundwater depth is ≥100 cm.

[0041] In this embodiment, different methods of transforming the soil are selected according to the conditions of the target saline-alkali soil. For example, for a soil with a shallow effective soil layer and multiple layers of sudden changes in texture, the soil contains both gravel and fine-textured soil. As an optional embodiment, a screening method is used to screen out the gravel in the soil, and then the screened gravel is turned to the lower part of the soil, and at the same time, the screened fine soil material is turned to the upper part. For a soil with a shallow effective soil layer, a thick compacted layer and a shallow burial depth, the soil generally does not contain gravel or contains less gravel, so gravel can be obtained from other areas and turned to the lower part of the soil, and the compacted layer can be broken and mixed at the same time.

[0042] In this embodiment, in the first year after the soil configuration structure is built, 1 to 2 irrigations are performed to wash out the salt, depending on the soil salt content, so as to reduce the salt content of the upper soil layer to below 2.0 g / kg. Specifically, the soil layer is irrigated until the soil is saturated or supersaturated, so that the saturated water and supersaturated water, driven by gravity, penetrate through the gravel layer and flow into the deep soil, thereby leaching the salt in the soil layer out of the soil layer. Thereafter, in the irrigation management of crop production, in order to prevent the soil layer and the gravel layer from establishing a water connection, the depth of the wetting front is less than the thickness of the upper soil layer during each irrigation. After many years of operation (generally between 15 and 24 years), the salt brought by the irrigation water and dust fall may gradually accumulate in the soil. If the soil salt content exceeds the salinization standard, for example, 2.0 g / kg, irrigation and salt washing are performed again.

[0043] Two specific embodiments are given below to illustrate the water-saving and salt-inhibiting method for improving saline-alkali land in arid areas according to the present embodiment.

[0044] Embodiment 1: A saline-alkali land in an arid area, 1570 meters above sea level, plateau, river valley plain, soil parent material-irrigation sediment, set up three pilots A, B, and C, among which pilot A is a pilot improved by the method of this embodiment, and pilot B is a pilot of the original soil body. The crop varieties planted in the three pilots are the same, and the agricultural production measures in planting are also the same. Among them, in pilot A, more than 120cm is uniform loam, below 120cm is gravel + coarse sand, the salt content of the tillage layer is 0.79g / kg, and the wheat yield per mu is about 500kg. In pilot B, more than 30cm is loam, 30~35cm is gravel, and below 35cm is sand-clay alternating layers. The soil body is approximately "shallow tillage layer type" and "texture variable type" soil body, the salt content of the tillage layer is 4.90g / kg, and the wheat yield per mu is about 250kg. Compared with position B, the yield at position A is increased by 100%.

[0045] Embodiment 2: Another arid saline-alkali land, 1052 meters above sea level, plateau, alluvial plain, irrigation sediment parent material, set up three pilots A, B, C, adjacent pilots are about 400 meters apart, the three pilots planted the same crop varieties, the agricultural production measures in the planting are also the same. Among them, the A pilot is a pilot improved by the method of this embodiment, the A pilot is a uniform loam above 68cm, gravel below 68cm, the salt content of the tillage layer is 0.94g / kg, and the wheat yield per mu is about 600kg. The B pilot is the original soil pilot, the B pilot is sandy loam above 120cm, but the soil from 30 to 80cm is extremely solid, the soil is approximately "uniform soil texture" and "thick compact layer and shallow burial depth" soil, the salt content of the tillage layer is 4.64g / kg, and the wheat yield per mu is about 400kg. Compared with the B position, the yield at the A position is increased by 50%.

[0046] In this embodiment, by constructing a soil layer and a gravel layer, the soil layer almost cuts off the up and down movement of unsaturated water at 1 meter, avoiding deep water leakage, and also cutting off the source of deep soil salt, so there is no need to wash salt every year, which can effectively reduce the annual salt washing irrigation water and deep irrigation water leakage. In the related art, for saline-alkali land in arid areas used as arable land, it is generally necessary to wash salt in winter and spring, requiring about 145m³ / mu of water, while non-salinized arable land using the method of this embodiment only needs to be irrigated about 30m³ / mu before sowing. The irrigation amount of corn and wheat during the whole growth period is 300~340m³ / mu, and the irrigation amount of cotton during the whole growth period is about 390m³ / mu. Using the method of this embodiment, the water leakage loss during the growth period of corn and cotton only accounts for 12~13% and 13~27% of the irrigation amount. Therefore, the "water-saving and salt-inhibiting" method of this embodiment can reduce the soil irrigation by 150-165 m³ / mu, which is equivalent to 31%-34% of the current irrigation amount, that is, it can reduce the agricultural water consumption per unit of cultivated land by more than 30%, control the soil salinity below 2.0 g / kg for a long time, and increase the crop production capacity of cultivated land by more than 50%. Under the condition of optimized water content, the wheat yield per mu is more than 450 kg.

[0047] Figure 2 The schematic diagram of the water-saving and salt-inhibiting system for improving saline-alkali land in arid areas provided by the embodiment of the present invention is shown. Figure 2 As shown, the water-saving and salt-inhibiting system includes a soil layer 21 and a gravel layer 22, wherein: Soil layer 21 is a soil layer whose soil particles are smaller than a first particle threshold, obtained by transforming the surface soil of the target saline-alkali land, the thickness of the soil layer is greater than a preset first thickness threshold, and the groundwater depth of the target saline-alkali land is below the soil layer; The gravel layer 22 is located below the soil layer 21, and is used to transform the soil below the soil layer of the target saline-alkali land into a soil layer with soil particles larger than the second particle threshold and smaller than the third particle threshold, and the thickness of the gravel layer is greater than the preset second thickness threshold; The transformed soil layer 21 is irrigated with water to wash away the salt until the salt content of the soil layer 21 is reduced to less than a preset salt threshold value; Crops are planted in the soil layer 21 after irrigation and salt removal. Each time the crops are irrigated, the depth of the irrigation wetting front is not greater than the thickness of the soil layer.

[0048] In this embodiment, as an optional embodiment, water is irrigated to wash away salt in the transformed soil layer until the salinity of the soil layer is reduced to less than a preset salinity threshold, including: The soil layer is irrigated until the soil is saturated or supersaturated, so that the saturated water or supersaturated water, driven by gravity, penetrates through the gravel layer and flows into the deep soil. The irrigation is stopped after the salinity of the soil layer is reduced to less than the preset salt threshold.

[0049] In this embodiment, as an optional embodiment, the water-saving and salt-inhibiting system further includes: The salt detection unit is used to detect the salt content of the target saline-alkali land before planting at preset annual intervals. When it is detected that the salt content exceeds the salt threshold, the soil layer is re-irrigated to wash away the salt.

[0050] It should be noted that similar numbers and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and are not to be understood as indicating or implying relative importance.

[0051] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application, rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application is described in detail with reference to the above-mentioned embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-mentioned embodiments within the technical scope disclosed in the present application, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application. They should all be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for improving saline-alkali land in arid areas, characterized in that: include: Improve the soil of the target saline-alkali land to obtain a soil layer with soil particles smaller than a first particle threshold and a gravel layer with soil particles larger than a second particle threshold but smaller than a third particle threshold; Obtaining the groundwater depth of the target saline-alkali land, setting the soil layer thickness to be greater than a preset first thickness threshold so that the improved soil layer is located above the groundwater depth, and setting the gravel layer thickness to be greater than a preset second thickness threshold; After the soil configuration structure including the improved soil layer and the gravel layer is completed, water is poured to wash away the salt so as to reduce the salinity of the soil layer to less than a preset salinity threshold; During each irrigation after planting crops in the soil configuration structure, the depth of the irrigation wetting front is no greater than the thickness of the soil layer.

2. The method for saving water and inhibiting salt in improving saline-alkali land in arid areas according to claim 1, characterized in that: The step of obtaining a soil layer in which soil particles are smaller than a first particle threshold and a gravel layer in which soil particles are larger than a second particle threshold but smaller than a third particle threshold comprises: Determine that the existing soil configuration characteristics of the target saline-alkali land are shallow effective soil layer and multi-layer texture mutation, adopt the screening method based on the first threshold of particles, based on the interphase filling method, screen out the gravel in the soil, turn the screened gravel to the bottom of the soil to form a gravel layer, and turn the screened fine soil material to the top of the gravel layer to form a soil layer; The soil configuration characteristics of the target saline-alkali land are determined to be uniform in texture, thick in compaction layer and shallow in burial depth. The soil is crushed and mixed, gravel is obtained from other areas and turned over to the bottom of the soil to form a gravel layer, and the crushed and mixed soil is turned over to the top of the gravel layer to form a soil layer.

3. The method for improving saline-alkali land in arid areas according to claim 1, characterized in that: The method of washing out the salt by watering to reduce the salinity of the soil layer to less than a preset salinity threshold value includes: The soil layer is irrigated until the soil is saturated or supersaturated, so that the saturated water or supersaturated water, driven by gravity, penetrates through the gravel layer and flows into the deep soil. The irrigation is stopped after the salinity of the soil layer is reduced to less than the preset salt threshold.

4. The method for improving saline-alkali land in arid areas according to any one of claims 1 to 3, characterized in that: The step of obtaining a soil layer in which soil particles are smaller than a first particle threshold comprises: The surface soil of the target saline-alkali land is transformed into a soil layer with more than 75% of soil particles less than 2mm and a depth greater than 50cm.

5. The method for saving water and inhibiting salt in improving saline-alkali land in arid areas according to any one of claims 1 to 4, characterized in that: The method further comprises: Every preset year, the salinity of the target saline-alkali land is tested before planting. When it is detected that the salinity exceeds the salinity threshold, water is re-irrigated to wash away the salt.

6. The method for saving water and inhibiting salt in arid saline-alkali land according to any one of claims 1 to 4, characterized in that: The groundwater burial depth is greater than the sum of the thickness of the soil layer and the thickness of the gravel layer.

7. The method for improving saline-alkali land in arid areas according to any one of claims 1 to 4, characterized in that: The first threshold value of particles is 2 mm, the second threshold value of particles is 2 mm, and the third threshold value of particles is 250 mm.

8. The method for saving water and inhibiting salt in improving saline-alkali land in arid areas according to any one of claims 1 to 4, characterized in that: The first thickness threshold is 100 cm, the second thickness threshold is 20 cm, and the salt threshold is 2.0 g / kg.

9. The method for saving water and inhibiting salt in improving saline-alkali land in arid areas according to any one of claims 1 to 4, characterized in that: The preset period is 15 years.

10. A water-saving and salt-inhibiting system for improving saline-alkali land in arid areas, characterized in that: include: Soil layer and gravel layer, among which, The soil layer is a soil layer whose soil particles are smaller than a first particle threshold, and is obtained by transforming the surface soil of the target saline-alkali land. The thickness of the soil layer is greater than a preset first thickness threshold, and the groundwater depth of the target saline-alkali land is below the soil layer; The gravel layer is located below the soil layer, and is used to transform the soil below the soil layer of the target saline-alkali land into a soil layer with soil particles larger than the second particle threshold and smaller than the third particle threshold, and the thickness of the gravel layer is greater than the preset second thickness threshold; Water is poured into the transformed soil layer to wash away the salt until the salinity of the soil layer is reduced to less than a preset salinity threshold; Crops are planted in the soil layer after the salt is washed off with water, and each time the crops are irrigated, the depth of the irrigation wetting front is not greater than the thickness of the soil layer.

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