Method for soil improvement and crop cultivation in seasonally frozen soil area of soda saline-alkali soil

Abstract

The application relates to the technical field of soil saline-alkali land improvement, and discloses a method for improving soda saline-alkali land soil and cultivating crops in a seasonal frozen soil area, which comprises the following steps: (1) digging a water collecting lake, a deep ditch and a plurality of shallow ditches in the saline-alkali land to be improved, so that the plurality of shallow ditches are connected with the deep ditch respectively, the deep ditch is communicated with the water collecting lake, the deep ditch is communicated with the water collecting lake, and the depth L1 of the deep ditch satisfies: L1=h1+Delta h1+h 01 , the ratio between the depth of the deep ditch and the depth of the shallow ditch is 1.5-3.5; (2) digging at least one vertical shaft between two adjacent shallow ditches, and the ratio between the depth of the vertical shaft and the depth of the deep ditch is 0.7-1.5; and (3) injecting water into the soil between the shallow ditches. The method can improve the soil structure, regulate the soil acidity and alkalinity, improve the micro-ecological environment of the soil, and make crops grow normally in a good soil environment.

Description

Technical Field

[0001] This invention relates to the field of soil salinity improvement technology, specifically to a method for improving soda salinity soil in seasonally frozen soil regions and for crop cultivation. Background Technology

[0002] Soda saline-alkali soils are mostly distributed in seasonally frozen soil regions of my country, with sodium carbonate and sodium bicarbonate as the main salt types. Unlike saline-alkali soils formed by intense surface evaporation and salinization, the formation of soda saline-alkali soils in frozen soil regions is also related to the freeze-thaw process. When soil water freezes in winter, salts in the groundwater rise with the water and accumulate in the frozen layer. When the frozen layer thaws in spring, the upper layer thaws first, and then, under excessive evaporation, the salts that were originally slowly accumulating in the upper layer of the frozen layer rapidly accumulate to the soil surface, with an intensity akin to an "eruption," exacerbating the soil salinization process. This also makes soda saline-alkali soils in seasonally frozen soil regions more difficult to manage than other types.

[0003] The Songnen Plain is one of the three major areas of concentrated distribution of soda saline-alkali soil in the world. It has a high groundwater level, high salt content, high pH, ​​and severely deteriorated soil structure. The soil is heavy when wet and compacted when dry, with poor soil permeability. The salt content of the topsoil is too high, reaching the level of severe salinization. Moreover, the area of ​​saline-alkali wasteland in the region is expanding rapidly.

[0004] High soil salinization disrupts soil aggregate structure, leading to soil compaction, reduced permeability and aeration, and severe damage to soil structure. This increases the likelihood of surface runoff and soil erosion. Simultaneously, saline-alkali soils exhibit increased ion concentrations, elevated pH, higher electrical conductivity and the exchangeable sodium ratio, decreased carbon and nitrogen mineralization, inhibited enzyme activity, and disrupted microbial populations and community structure. This negatively impacts soil microbial activity and organic matter transformation, resulting in decreased soil nutrient utilization, reduced organic matter content, and lower soil fertility. Consequently, soil nutrient depletion ultimately leads to poor crop growth, decreased quality, and reduced yield. In severe cases of salinization, crop growth becomes difficult and yields are reduced, severely damaging the regional ecological environment.

[0005] Currently, the treatment of soda saline-alkali land involves planting cash crops such as rice, combined with soil amendments such as desulfurized gypsum. However, this method is not sustainable due to limitations in freshwater resources and land use types. Furthermore, the unique physical and chemical properties of soda saline-alkali soil in permafrost regions result in low yields and lower quality of crops like rice compared to conventional paddy fields, leading to unsatisfactory soil improvement results. Therefore, no effective method has been provided for the improvement of soda saline-alkali land in the permafrost region of the Songnen Plain. Given these reasons, there is an urgent need to provide a soil improvement method that can effectively improve the physical and chemical properties and ecological environment of the soil, reduce soil salinization, and increase crop yields. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems that, in the treatment of soda saline-alkali land in seasonally frozen soil areas, the degree of salinization and salt return in the Songnen Plain remains severe after the implementation of existing improvement technologies, resulting in serious damage to soil structure and limited crop growth. This invention provides a method for soil improvement and crop cultivation that can improve the physical and chemical properties and microbial environment of the soil, promote the healthy restoration of the soil ecological environment, and maintain normal crop growth.

[0007] To achieve the above objectives, a first aspect of the present invention provides a method for soil improvement in soda-saline-alkali land in seasonally frozen soil regions, wherein the method includes:

[0008] (1) In the saline-alkali land to be improved, a catchment lake, a deep ditch, and multiple shallow ditches are excavated, such that each of the shallow ditches is connected to a deep ditch, and the deep ditch is connected to the catchment lake. The depth L1 of the deep ditch satisfies: L1=h1+Δh1+h 01 Where h1≥3m, Δh1 is the groundwater head difference in meters; h 01 The depth of the water level in the deep ditch is measured in meters (m); the ratio between the depth of the deep ditch and the depth of the shallow ditch is 1.5-3.5.

[0009] (2) At least one vertical shaft is excavated between two adjacent shallow trenches, wherein the ratio between the depth of the vertical shaft and the depth of the deep trench is 0.7-1.5;

[0010] (3) Water is poured into the soil between the shallow trenches.

[0011] A second aspect of the present invention provides a method for cultivating crops in seasonally frozen soil regions with soda-saline-alkali soil, the method comprising:

[0012] (1) The saline-alkali land to be improved is improved by the method according to the first aspect of the present invention;

[0013] (2) Plant crops on the improved land.

[0014] Through the above technical solutions, the present invention achieves at least the following beneficial technical effects: the method of the present invention can improve soil structure and regulate soil acidity and alkalinity, such as porosity, permeability, soil air capacity, pH, and alkalinity, thereby promoting the formation of a good micro-ecological environment in the soil, increasing the abundance of microorganisms, and enabling crops to grow normally in a good soil environment. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating the measurement of the critical depth of groundwater in this invention. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] The first aspect of this invention provides a method for soil improvement, wherein the method includes:

[0018] (1) In the saline-alkali land to be improved, a catchment lake, a deep ditch, and multiple shallow ditches are excavated, such that each of the shallow ditches is connected to a deep ditch, and the deep ditch is connected to the catchment lake. The depth L1 of the deep ditch satisfies: L1=h1+Δh1+h0; where h1≥3m, Δh1 is the groundwater head difference in meters; h 01 The depth of the water level in the deep ditch is measured in meters (m); the ratio between the depth of the deep ditch and the depth of the shallow ditch is 1.5-3.5.

[0019] (2) At least one vertical shaft is excavated between two adjacent shallow trenches, wherein the ratio between the depth of the vertical shaft and the depth of the deep trench is 0.7-1.5;

[0020] (3) Water is poured into the soil between the shallow trenches.

[0021] According to the present invention, the depth of furrows, deep furrows and shallow furrows refers to the vertical distance from the bottom of the furrow to the ground surface.

[0022] According to this invention, h1 refers to the highest daily groundwater level of the saline-alkali land to be improved, and h1 ≥ "critical groundwater depth" (critical groundwater depth, also known as critical water level, refers to the shallowest groundwater depth that limits secondary soil salinization, such as...). Figure 1 As shown), in seasonally frozen soil areas, the "critical depth of groundwater" is generally greater than in other areas due to freeze-thaw cycles. Preferably, h1 ≥ 3m, more preferably, h1 is 3.2-4.5m; Δh1 is the difference in stable groundwater head, preferably Δh1 is 0.1-0.2m; h 01 The water level depth in the deep trench, preferably h 01 It is 0.1-0.2m.

[0023] According to the present invention, the highest level of groundwater refers to the closest distance between the horizontal plane of groundwater and the Earth's surface.

[0024] According to the present invention, the water level depth in the deep trench refers to the vertical height between the water level in the deep trench and the bottom of the deep trench.

[0025] According to the present invention, the depth of the shallow trench can be adjusted according to the maximum root growth depth of the planted crop and the highest water level of the groundwater.

[0026] According to some embodiments of the present invention, the depth L2 of the shallow trench satisfies: L2 = h2 + Δh2 + h 02 ;

[0027] Where h2≥0.5m, Δh2 is the groundwater head difference in meters; h 02 The depth of the water level in the shallow ditch is expressed in meters (m).

[0028] According to the present invention, the groundwater steady head difference (Δh1 or Δh2) is a commonly used parameter in hydraulics and can be measured using conventional methods.

[0029] According to the present invention, the water level depth in the shallow ditch refers to the vertical height between the water level in the shallow ditch and the bottom of the ditch.

[0030] According to the present invention, h2 refers to the highest water level of the groundwater in the saline-alkali land to be improved during the rainy season, and h2 ≥ "the standard value for drainage of crops in cultivated areas". The drainage depth for common crops such as cotton and corn is 1-1.2m, and the drainage depth for wheat, soybeans and sorghum is 0.8-1m.

[0031] Preferably, h2 is 0.8-1.2m; Δh2 is 0.1-0.2m; h 02 It is 0.1-0.2m.

[0032] Preferably, the depth of the deep trench is 3.2-4.5m, and the depth of the shallow trench is 1-1.4m.

[0033] According to some embodiments of the present invention, the deep trench and the shallow trench are perpendicularly connected. In one specific embodiment of the present invention, for a rectangular saline-alkali land to be improved, the deep trench is arranged in the length direction and the shallow trench is arranged in the width direction.

[0034] According to the present invention, when the depth of the deep trench and the depth of the shallow trench meet the above-mentioned limitations, on the one hand, excess water in the soil can be drained away more efficiently during the rainy season and floods, avoiding waterlogging and waterlogging damage to crops. On the other hand, the salt content in the soil is reduced, which can weaken the salinization and alkalization effects of salt on the soil, thereby further improving the soil structure, especially increasing the soil porosity, soil air capacity and permeability, providing a good soil environment for microbial growth, promoting microbial activity and nutrient conversion, and increasing crop yield.

[0035] According to some embodiments of the present invention, the method further includes excavating a plurality of ridges between adjacent shallow trenches, the ridges being excavated parallel to the shallow trenches.

[0036] Preferably, the ridge body consists of ridge platforms and furrows.

[0037] Preferably, the width of the ridge is 50-90cm, and the spacing between the ridges is 15-20cm.

[0038] According to the present invention, the ridge body is composed of raised ridges and lower furrows, with furrows between adjacent ridges. The raised ridges are used for planting crops, and the lower furrows are used for drainage.

[0039] According to the present invention, the height of the ridge refers to the vertical distance from the bottom of the furrow to the top of the ridge.

[0040] Preferably, the width to height ratio of the ridge is (1.5-3.5):1.

[0041] Preferably, the ratio of the width to the depth of the furrow is (0.5-1):1.

[0042] More preferably, the width of the ridge is 50-70cm and the height is 20-30cm.

[0043] More preferably, the width of the furrow is 15-20cm and the depth is 20-30cm.

[0044] The inventors of this invention have discovered that ridges affect soil insulation, drainage, and moisture retention. When the width and height of the ridges meet the aforementioned preferred ranges, soil permeability is improved, leading to better reduction of soil moisture content, improvement of soil structure, soil thermal conditions, and soil aeration, and an increase in redox potential. This, in turn, promotes the reproduction of soil microorganisms, accelerates the conversion and utilization of readily available nutrients in the soil, effectively improves the soil microecological environment, promotes root development, enhances root vitality and function, and improves the absorption and utilization of water and nutrients by crop roots, ultimately increasing crop yield.

[0045] According to the present invention, the catchment lake is connected to the drainage outlet of the deep ditch. The catchment lake is located at the lowest point of the saline-alkali land improvement area or at the lowest point of the groundwater level, ensuring that surface water and groundwater can be retained and drained into the catchment lake, thereby achieving the effect of water collection and balancing the regional groundwater level. The catchment lake balances the regional groundwater level by relying on the regional groundwater potential difference.

[0046] According to the present invention, the excavation depth of the catchment lake should ensure that the water level in the lake is controlled below the critical groundwater depth on a daily basis. The depth setting should also refer to the groundwater level depth, drainage volume, and other conditions in the saline-alkali land improvement area. Preferably, the depth of the catchment lake is 10-20m.

[0047] According to some embodiments of the present invention, the area of ​​the catchment lake is 3%-5% of the area of ​​the saline-alkali land to be improved.

[0048] According to the present invention, the spacing between two adjacent shallow trenches can be adjusted according to the salt drainage capacity of a single shallow trench. Preferably, the spacing between two adjacent shallow trenches is 60-100 times the depth of the shallow trench.

[0049] According to the present invention, there is no particular limitation on the number of deep trenches dug in the saline-alkali land to be improved; multiple deep trenches can be dug according to the area of ​​the saline-alkali land to be improved. In one specific embodiment of the present invention, the area enclosed by one deep trench and multiple shallow trenches in the saline-alkali land to be improved is taken as the smallest unit, and other areas are arranged in the same manner according to the design of the smallest unit. The inventors of the present invention have found that the smaller the spacing between the deep trenches, the more beneficial it is to lower and control the daily groundwater level and prevent salinization.

[0050] According to the present invention, the spacing between two adjacent deep trenches can be adjusted according to the salt drainage capacity of a single deep trench. Preferably, the spacing between two adjacent deep trenches is 60-100 times the depth of the deep trench.

[0051] According to the present invention, the width of a shallow or deep trench refers to the cross-sectional width of the trench.

[0052] According to some embodiments of the present invention, the width W1 of the deep trench and the slope coefficient S1 of the deep trench, the bottom width w1 of the deep trench, and the depth L1 of the deep trench satisfy the following relationship: W1 = L1 × S1 × 2 + w1.

[0053] According to some embodiments of the present invention, the width W2 of the shallow ditch and the slope coefficient S2 of the shallow ditch, the bottom width w2 of the shallow ditch, and the depth D2 of the shallow ditch satisfy the following relationship: W2 = L2 × S2 × 2 + w2.

[0054] According to the present invention, the units of S1, L1, S2, L2, w1, and w2 are all meters (m). The slope coefficient represents a constant of slope, which refers to the angle of inclination between the shallow or deep ditch and the ground. Since the soil texture of soda-saline-alkali land in seasonally frozen soil areas is relatively heavy, preferably, the slope coefficient S1 of the deep ditch is 1.5-2, and the bottom width w1 of the deep ditch is 1-3 meters; the slope coefficient S2 of the shallow ditch is 1-1.5, and the bottom width w2 of the shallow ditch is 0.5-1 meter.

[0055] According to the present invention, the depth of the shaft is 1-2m greater than the "critical depth of groundwater". Preferably, the depth of the shaft is 3-5m and the diameter is 2-3m.

[0056] According to some embodiments of the present invention, a water level monitor and / or a water pump are also provided in the shaft.

[0057] According to the present invention, when the water level detector installed in the shaft detects that the groundwater level exceeds the "critical depth", the water pump is started to drain the water, so that the groundwater level drops below the "critical depth", thereby accurately controlling the daily groundwater level.

[0058] According to the present invention, the preferred time for water injection is after the frozen layer thaws in spring and / or in autumn.

[0059] According to the present invention, there is no particular limitation on the method of water injection, as long as it can moisten the soil and cause water to accumulate in the furrows. For example, the inlets and outlets of shallow and deep furrows can be blocked, and water can be pumped into the furrows using a water pump.

[0060] Preferably, the water injection method includes injecting water into the soil of the raised bed, such that the water reaches a depth of 0.5-1m in the soil or water is discharged in a shallow ditch.

[0061] Preferably, the method further includes deep tillage and rotary tillage of the soil before excavating deep and shallow trenches in the saline-alkali land to be improved, so that the soil particle size is in the range of 0.5-1cm.

[0062] According to the present invention, the soil in saline-alkali land is severely compacted and has poor permeability. Deep plowing and rotary tillage can reconstruct the soil structure of the topsoil, improve the soil aggregate structure, and reduce the salinity of the topsoil, thereby creating a balanced soil environment in terms of water, fertilizer, air and heat.

[0063] According to the present invention, there are no particular limitations on the methods of deep tillage and rotary tillage, such as using a tiller and a rotary tiller.

[0064] According to some embodiments of the present invention, the soil of the saline-alkali land to be improved has a salt content ≥6g / kg, an alkalinity ≥30%, a pH of 8.5-10.5, a permeability coefficient of 0.85-1.2mm / min, and is clay loam.

[0065] According to the present invention, the soil salinity is determined by the residue drying method. The specific operation process includes: taking a certain amount of soil leachate and placing it in a porcelain evaporating dish, evaporating it to dryness on a water bath, adding H2O2 to oxidize the organic matter, and then drying it in an oven at 105-110℃, weighing it, and obtaining the mass of the dried residue.

[0066] According to the present invention, the method for calculating soil alkalinity is as specified in "LY / T 1249-1999 Calculation of Soil Alkalinity", where soil alkalinity (%) = 100 × (exchangeable sodium ion content / cation exchange capacity); wherein, the soil exchangeable sodium ion content and cation exchange capacity are determined according to the method specified in "NY / T 295-1995 Determination of Cation Exchange Capacity and Exchangeable Bases in Neutral Soils".

[0067] According to the present invention, soil porosity is determined by the volumetric method, and soil porosity (%) = 100% × (1 - bulk density / specific gravity); where bulk density refers to the ratio of the weight of soil to the volume it occupies without damaging the soil structure; and specific gravity refers to the ratio of the actual volume occupied by soil solid particles to the weight of the same volume of water.

[0068] According to the present invention, the soil permeability coefficient is determined by the double-ring method. The specific operation process includes: taking an undisturbed soil sample with a ring cutter, soaking it in water, and then, under a unit water pressure gradient, calculating the water flow velocity per unit soil cross-sectional area perpendicular to the water flow direction according to Darcy's law.

[0069] A second aspect of the present invention provides a method for cultivating crops in seasonally frozen soil regions with soda-saline-alkali soil, the method comprising:

[0070] (1) The saline-alkali land to be improved is improved by the method according to the first aspect of the present invention;

[0071] (2) Plant crops on the improved land.

[0072] According to some embodiments of the present invention, the crop is selected from at least one of sunflower, sugar beet and soybean.

[0073] According to the present invention, after planting crops on improved land, the soil moisture content of the topsoil during the crop growth period is regulated to further promote crop growth. Preferably, the soil moisture content is controlled at 15-20% by weight.

[0074] According to the present invention, regulating the soil moisture content of the tillage layer during the crop growth period refers to the timely replenishment of irrigation water or drainage by routinely monitoring the soil moisture content, so as to keep the soil field water holding capacity stably controlled at 15-20% by weight, thereby controlling the soil salinity concentration, reducing salt damage and alkali damage, and maintaining normal crop growth.

[0075] The present invention will be described in detail below through embodiments.

[0076] In the following examples, the saline-alkali land to be improved is located in Da'an City, Jilin Province. The soil salt content is >6g / kg, the alkalinity is 30%, and it is a severely saline-alkali soil. The soil texture is clay loam, the pH is 10.2, and the permeability coefficient is 0.83mm / min.

[0077] The total area of ​​saline-alkali land to be improved is 500 hm². 2 (Length × Width = 1890m × 2650m).

[0078] Example 1

[0079] (1) The saline-alkali land was deep-plowed and rotary-tilled using a pulverized soil tillage machine, so that the soil particle size was 0.8±0.2cm;

[0080] (2) At 54600m 2 One deep ditch and two shallow ditches were dug in the saline-alkali land to be improved. The shallow ditches extended and connected with the deep ditch, and the deep ditch connected with the catchment lake (with an area of ​​2730m²). 2 ) Connect;

[0081] The highest daily groundwater level (h1) of the saline-alkali land to be improved is 3.3m, the groundwater head difference (Δh1) is 0.1m, and the water level depth in the deep ditch (h) is... 01 The depth of the ditch is 0.1m, the bottom width (w1) of the ditch is 2m, the slope coefficient (S1) is 1.5, the depth (L1) of the ditch is 3.5m, and the width (W1) of the ditch is 12.5m.

[0082] The highest groundwater level (h2) in the saline-alkali land to be improved during the rainy season is 1.2m, the groundwater head difference (Δh2) is 0.1m, and the water level depth in the shallow ditch (h) is... 02 The ditch has a bottom width (w2) of 0.1m, a slope coefficient (S2) of 1.5, a depth (L2) of 1.4m, a width (W2) of 4.7m, and a spacing of 140m.

[0083] (3) 150 ridges are dug between two adjacent shallow ditches. The width of the ridge is 90cm. The width of the ridge platform is 70cm and the height of the ridge platform is 30cm. The width of the ridge ditch is 20cm and the depth of the ridge ditch is 30cm. A vertical well is dug in the middle of the smallest rectangle of saline-alkali land enclosed by two adjacent shallow ditches and deep ditches. The depth of the vertical well is 5m and the diameter of the well is 3m.

[0084] (4) Pour water into the soil of the ridge, and stop pouring water after the water reaches 1m into the soil. Let it stand and let the water drain naturally.

[0085] (5) Sunflowers were planted on the improved saline-alkali land and conventional cultivation and management were carried out. Sunflowers were sown in single rows with a plant spacing of 50cm.

[0086] The final yield of sunflower seeds was measured to be 150 kg / mu.

[0087] Example 2

[0088] (1) The saline-alkali land was deep-plowed and rotary-tilled using a pulverized soil tillage machine, so that the soil particle size was 0.8±0.2cm;

[0089] (2) at 189000m 2 One deep ditch and four shallow ditches were dug in the saline-alkali land to be improved. The shallow ditches extended and connected with the deep ditch, and the deep ditch connected with the catchment lake (with an area of ​​9450m²). 2 ) Connect;

[0090] The highest daily groundwater level (h1) of the saline-alkali land to be improved is 3.3m, the groundwater head difference (Δh1) is 0.1m, and the water level depth in the deep ditch (h) is... 01 The depth of the ditch is 0.1m, the bottom width (w1) of the ditch is 2m, the slope coefficient (S1) is 1.5, the depth (L1) of the ditch is 3.5m, and the width (W1) of the ditch is 12.5m.

[0091] The highest groundwater level (h2) in the saline-alkali land to be improved during the rainy season is 1.2m, the groundwater head difference (Δh2) is 0.1m, and the water level depth in the shallow ditch (h) is... 02 The ditch has a bottom width (w2) of 0.1m, a slope coefficient (S2) of 1.5, a depth (L2) of 1.4m, a width (W2) of 4.7m, and a spacing of 120m.

[0092] (3) 165 ridges are dug between two adjacent shallow ditches. The width of the ridge is 70cm. The width of the ridge platform is 50cm and the height of the ridge platform is 30cm. The width of the ridge ditch is 20cm and the depth of the ridge ditch is 30cm. A vertical well is dug in the middle of the smallest rectangle of saline-alkali land enclosed by two adjacent shallow ditches and deep ditches. The depth of the vertical well is 5m and the diameter of the well is 3m.

[0093] (4) Pour water into the soil of the ridge, and stop pouring water after the water reaches 1m into the soil. Let it stand and let the water drain naturally.

[0094] (5) Sunflowers were planted on the improved saline-alkali land and conventional cultivation and management were carried out. Sunflowers were sown in single rows with a plant spacing of 50cm.

[0095] The final yield of sunflower seeds was measured to be 180 kg / mu.

[0096] Example 3

[0097] The method of Example 2 differs in that the width of the ridge is 90cm, the width of the ridge platform is 70cm, the height of the ridge platform is 10cm, the width of the furrow is 20cm, and the depth is 10cm.

[0098] The final yield of sunflower seeds was measured to be 100 kg / mu.

[0099] Comparative Example 1

[0100] The method in Example 2 was followed, except that the soil was not improved and salt-tolerant sunflowers were planted directly. The final yield of sunflowers was measured to be 50 kg / mu.

[0101] Comparative Example 2

[0102] The method of Example 2 differs in that the depth of the deep trench is 1.5m, the depth of the shallow trench is 1.3m, and the depth of the vertical shaft is 2m.

[0103] The final yield of sunflower seeds was measured to be 80 kg / mu.

[0104] Test Example 1

[0105] Before crop transplanting and after crop harvesting, the soil physicochemical properties of the saline-alkali land in the examples and comparative examples were measured, and the results are shown in Table 1.

[0106] pH values ​​were measured using a pH meter.

[0107] The salt content was determined by the residue drying method. The specific operation process includes: taking a certain amount of soil leachate and placing it in a porcelain evaporating dish, evaporating it to dryness on a water bath, adding H2O2 to oxidize the organic matter, and then drying it in an oven at 105-110℃, weighing it, and obtaining the mass of the dried residue.

[0108] Soil alkalinity (%) = 100 × (exchangeable sodium ion content / cation exchange capacity). The calculation method for alkalinity is given in "LY / T 1249-1999 Calculation of Soil Alkalinity". The exchangeable sodium ion content and cation exchange capacity of the soil are determined according to the method in "NY / T 295-1995 Determination of Cation Exchange Capacity and Exchangeable Bases in Neutral Soils".

[0109] Soil porosity was determined using the volumetric method. Soil porosity (%) = 100% × (1 - bulk density / specific gravity). Bulk density is the ratio of the weight of soil to its volume without damaging the soil structure. Specific gravity is the ratio of the actual volume occupied by soil solid particles to the weight of the same volume of water.

[0110] The permeability coefficient was determined using the double-ring method. The specific operation process included: taking an undisturbed soil sample with a ring cutter, soaking it in water, and then, under a unit water pressure gradient, calculating the water flow velocity per unit soil cross-sectional area perpendicular to the water flow direction according to Darcy's law.

[0111] Microbial abundance was determined using real-time quantitative PCR, a method that uses internal or external references to quantify specific DNA sequences in the test sample.

[0112] Table 1

[0113]

[0114] As shown by the data from Examples 1-2 in Table 1, the saline-alkali soil before planting had high pH, ​​salinity, and alkalinity, and low porosity, permeability, and microbial abundance. After planting, the pH, salinity, and alkalinity of the improved saline-alkali soil decreased, while the porosity, permeability, and microbial abundance increased. The degree of soil salinization, soil structure, and microecological environment were effectively improved. Therefore, the method of this invention can improve the porosity, permeability, pH, and alkalinity of saline-alkali soil, thereby promoting the formation of a favorable microecological environment, increasing microbial abundance, enabling crops to grow normally in a good soil environment, and increasing yield.

[0115] A comparison of Example 2 and Example 3 shows that the preferred method can further improve the soil structure, pH and micro-ecological environment of saline-alkali land, and increase yield.

[0116] In Comparative Example 1, without soil improvement, the soil before planting was severely salinized, compacted, poorly aerated, and had a poor microecological environment. After planting crops, the soil salinization worsened, the soil compaction did not improve, and the microecological environment became even worse, leading to reduced crop yield. In Comparative Example 2, the ratio between the depth of deep furrows and the depth of shallow furrows decreased, the degree of soil salinization increased, the soil became compacted, the aeration decreased, and the microecological environment did not improve, leading to reduced crop yield.

[0117] In summary, the method described in this invention can further improve the soil structure, pH, and microecological environment of saline-alkali land, thereby increasing yield.

[0118] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for improving soda-saline-alkali soil in seasonally frozen soil regions, characterized in that, The method includes: (1) In the saline-alkali land to be improved, a catchment lake, a deep ditch and multiple shallow ditches are excavated, such that each of the shallow ditches is connected to the deep ditch, and the deep ditch is connected to the catchment lake. The depth L1 of the deep ditch satisfies: L1=h1+Δh1+h 01 Where h1≥3m, Δh1 is the groundwater head difference in meters; h 01 The depth of the water level in the deep ditch is measured in meters (m); the ratio between the depth of the deep ditch and the depth of the shallow ditch is 1.5-3.

5. (2) At least one vertical shaft is excavated between two adjacent shallow trenches, wherein the ratio between the depth of the vertical shaft and the depth of the deep trench is 0.7-1.5; (3) Inject water into the soil between the shallow trenches; The depth L2 of the shallow trench satisfies: L2 = h2 + Δh2 + h 02 h2≥0.5m, Δh2 is the steady groundwater head difference, in meters; h 02 The depth of the water level in the shallow ditch is expressed in meters (m). The width W1 of the deep ditch satisfies the following relationship with the slope coefficient S1, the bottom width w1, and the depth L1 of the deep ditch: W1 = L1 × S1 × 2 + w1; the slope coefficient S1 of the deep ditch is 1.5-2, and the bottom width w1 of the deep ditch is 1-3m. The width W2 of the shallow ditch satisfies the following relationship with the slope coefficient S2, the bottom width w2, and the depth L2 of the shallow ditch: W2 = L2 × S2 × 2 + w2; the slope coefficient S2 of the shallow ditch is 1-1.5, and the bottom width w2 of the shallow ditch is 0.5-1m.

2. The method according to claim 1, wherein, The depth L1 of the trench satisfies: L1 = h1 + Δh1 + h 01 h1 is 3.2-4.5m, Δh1 is 0.1-0.2m, h 01 It is 0.1-0.2m; And / or, the method further includes excavating a plurality of ridges between adjacent shallow trenches, the ridges being excavated parallel to the shallow trenches.

3. The method according to claim 2, wherein, The ridge consists of ridge platforms and furrows.

4. The method according to claim 3, wherein, The width of the ridge is 50-90cm, and the spacing between the ridges is 15-20cm.

5. The method according to claim 3, wherein, The width to height ratio of the ridge is (1.5-3.5):

1.

6. The method according to claim 3, wherein, The width to depth ratio of the furrow is (0.5-1):

1.

7. The method according to claim 1, wherein, The area of ​​the catchment lake is 3%-5% of the area of ​​the saline-alkali land to be improved; And / or, the distance between two adjacent shallow grooves is 60-100 times the depth of the shallow groove.

8. The method according to claim 1, wherein, h2 is 0.8-1.2m; Δh2 is 0.1-0.2m; h 02 It is 0.1-0.2m; And / or, the deep trench is perpendicularly connected to the shallow trench.

9. The method according to claim 2, wherein, The depth of the shaft is 3-5m and the diameter is 2-3m.

10. The method according to claim 3, wherein, The water injection method includes injecting water into the soil of the ridge, such that the water reaches 0.5-1m into the soil or water is discharged in shallow ditches.

11. The method according to claim 2, wherein, The method also includes deep tillage and rotary tillage of the soil before excavating deep and shallow trenches in the saline-alkali land to be improved, so that the soil particle size is in the range of 0.5-1cm.

12. The method according to any one of claims 1-11, wherein, The shaft is also equipped with a water level monitor and / or a water pump.

13. The method according to any one of claims 1-11, wherein, The saline-alkali land to be improved has a salt content ≥6g / kg, alkalinity ≥30%, pH 8.5-10.5, permeability coefficient 0.85-1.2mm / min, and is clay loam soil.

14. A method for cultivating crops in seasonally frozen soil regions with soda-saline-alkali soil, characterized in that, The method includes: (1) The method according to any one of claims 1-13 is used to improve the saline-alkali land to be improved; (2) Planting crops on the improved land.

15. The method according to claim 14, wherein, The crop is selected from at least one of sunflower, sugar beet and soybean.

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