Method for soil improvement and crop cultivation of soda saline-alkali soil in seasonal frozen soil region

Abstract

The invention relates to the technical field of soil saline-alkali soil improvement, and discloses a seasonal permafrost region soda saline-alkali soil improvement and crop cultivation method, which comprises the following steps: (1) digging a catchment lake, a deep ditch and a plurality of shallow ditches in saline-alkali soil to be improved, enabling the plurality of shallow ditches to be respectively connected with the deep ditch, enabling the deep ditch to be communicated with the catchment lake, and enabling the deep ditch to be communicated with the catchment lake; the deep ditch is communicated with the catchment lake, the depth L1 of the deep ditch meets the condition that L1 = h1 + delta h1 + h01, and the ratio of the depth of the deep ditch to the depth of the shallow ditch is 1.5-3.5; (2) digging at least one vertical shaft between two adjacent shallow trenches, wherein the ratio of the depth of the vertical shaft to the depth of the deep trench is 0.7-1.5; and (3) injecting water into the soil between the shallow ditches. According to the method, the soil structure can be improved, the soil acid-base property can be adjusted, the micro-ecological environment of the soil can be improved, and crops can normally grow in a good soil environment.

Description

Technical Field

[0001] The invention relates to the technical field of soil saline-alkali land improvement, and in particular to a method for improving soil in soda saline-alkali land in a seasonally frozen soil zone and cultivating crops. Background Art

[0002] Soda saline-alkali soil is mostly distributed in seasonal frozen soil areas in my country, and the salt types are mainly sodium carbonate and sodium bicarbonate. Unlike saline-alkali soil formed by intense surface evaporation and salinization, the formation of soda saline-alkali soil in frozen soil areas is also related to the freeze-thaw process. When the soil water freezes in winter, the salt in the groundwater rises with the water and accumulates in the frozen layer. When the temperature rises in spring and the frozen layer melts, the upper layer begins to melt first. Then, under the effect of excessive evaporation, the salt that originally accumulated slowly in the upper layer of the frozen layer quickly gathers on the soil surface, with an intensity like an "eruption", exacerbating the soil salinization process. This also makes soda saline-alkali soil in seasonal frozen soil areas more difficult to control than other types.

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

[0004] When the soil is highly salinized, the soil aggregate structure is destroyed, the soil becomes compacted, the water permeability and air permeability of the soil are reduced, the soil structure is seriously damaged, and the possibility of surface runoff and soil erosion increases. At the same time, the ion concentration in the soil solution of saline-alkali soil increases, the pH value increases, the conductivity and exchangeable sodium ratio increases, the mineralization of carbon and nitrogen decreases, the enzyme activity in the soil is inhibited, the number of microorganisms and the community structure are destroyed, which in turn affects the activity of soil microorganisms and the transformation of organic matter, and reduces the soil nutrient utilization rate, organic matter content and soil fertility, resulting in soil nutrient barrenness, and ultimately causing poor crop growth, quality decline, and yield reduction. Severe salinization will also cause difficulties in crop growth and no yield, etc., seriously damaging the regional ecological environment.

[0005] At present, the treatment method of soda saline-alkali land is to plant economic crops such as rice and use improvement materials such as desulfurized gypsum. However, due to the limitations of freshwater resources and the type of cultivated land use, this method is not sustainable. On the other hand, due to the special physical and chemical properties of soda saline-alkali land in the permafrost area, the yield of crops such as rice is low and the quality is not as good as that of conventional rice fields, and the effect of soil improvement is not satisfactory. Therefore, no effective method has been given for the improvement of soda saline-alkali land in the permafrost area of ​​Songnen Plain. In view of the above reasons, it is urgent to provide a soil improvement method that can effectively improve the physical and chemical properties and ecological environment of the soil, reduce the degree of soil salinization, and increase crop yields. Summary of the invention

[0006] The purpose of the present invention is to overcome the problem that in the management of soda saline-alkali land in seasonal frozen soil areas, the salinization degree and salt return phenomenon of the land in the Songnen Plain are still serious after the implementation of the existing improvement technology, resulting in serious damage to the soil structure and restricted crop growth. A method for soil improvement and crop cultivation is provided, which can improve the physical and chemical properties and microbial environment of the soil, promote the healthy recovery of the soil ecological environment, and maintain the normal growth of crops.

[0007] In order to achieve the above object, the present invention provides a method for improving soil in soda saline-alkali land in a seasonally frozen soil region in a first aspect, wherein the method comprises:

[0008] (1) A water collection lake, a deep ditch and multiple shallow ditches are excavated in the saline-alkali land to be improved, so that the multiple shallow ditches are connected to the deep ditch, the deep ditch is connected to the water collection lake, and the depth L1 of the deep ditch satisfies: L1 = h1 + Δh1 + h 01 ; where h1≥3m, Δh1 is the underground stable water head difference, in m; h 01 is the water level depth in the deep ditch, in meters; the ratio between the depth of the deep ditch and the depth of the shallow ditch is 1.5-3.5;

[0009] (2) digging at least one vertical shaft 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 injected into the soil between the shallow trenches.

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

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

[0013] (2) Planting crops on improved land.

[0014] Through the above technical scheme, the present invention achieves at least the following beneficial technical effects: the method of the present invention can improve the soil structure and adjust the soil acidity and alkalinity, such as porosity, permeability, soil air capacity, pH, and alkalinity, thereby promoting the formation of a good microecological environment in the soil, increasing the abundance of microorganisms, and allowing crops to grow normally in a good soil environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of measuring the critical depth of groundwater in the present invention. DETAILED DESCRIPTION

[0016] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0017] A first aspect of the present invention provides a method for soil improvement, wherein the method comprises:

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

[0019] (2) digging at least one vertical shaft 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 injected into the soil between the shallow trenches.

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

[0022] According to the present invention, h1 refers to the highest level of groundwater in the saline-alkali land to be improved, and h1 ≥ "critical depth of groundwater" (critical depth of groundwater is also called critical water level, which refers to the shallowest groundwater depth that limits the occurrence of secondary salinization of soil, such as Figure 1 As shown in the figure, the "critical depth of groundwater" in seasonal frozen soil areas is generally greater than that in other areas due to freeze-thaw reasons. Preferably, h1≥3m, more preferably, h1 is 3.2-4.5m; Δh1 is the underground stable water head difference, preferably, Δh1 is 0.1-0.2m; h 01 is 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 the groundwater table refers to the shortest distance between the horizontal surface of the groundwater and the ground 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 crops and the highest liquid level of the groundwater level.

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

[0027] Where, h2≥0.5m, Δh2 is the underground stable water head difference, in m; h 02 It is the water level depth in the shallow ditch, in m.

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

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

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

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

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

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

[0034] According to the present invention, when the depth of the deep ditch and the depth of the shallow ditch meet the above-mentioned limitations, on the one hand, the excess water in the soil can be drained away more efficiently and quickly during the rainy season and flood disasters, thereby preventing crops from being damaged by waterlogging and waterlogging. At the same time, the salt content in the soil is reduced, and the salinization and alkalization effects of salt on the soil can be weakened, thereby further improving the soil structure, especially improving the porosity, air capacity and permeability of the soil, providing a good soil environment for the growth of microorganisms, promoting the activity of microorganisms and the conversion of nutrients, and increasing crop yields.

[0035] According to some embodiments of the present invention, the method further comprises excavating a plurality of ridges between adjacent shallow grooves, wherein the ridges are opened in parallel with the shallow grooves.

[0036] Preferably, the ridge body consists of a ridge platform and a ridge ditch.

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

[0038] According to the present invention, the ridge body is composed of high convex ridge platforms and low concave ridge ditches, and the ditches are between adjacent ridge platforms. The high convex ridge platforms are used for planting crops, and the low concave ridge ditches are used for drainage.

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

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

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

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

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

[0044] The inventors of the present invention have found that the ridge body has an impact on the heat preservation, drainage and moisture retention of the soil. When the width and height of the ridge body meet the above preferred range, the soil permeability is good, the soil water content can be better reduced, the soil structure, soil thermal conditions, soil ventilation conditions can be improved, the redox potential can be increased, and the reproduction of soil microorganisms can be promoted, the transformation and utilization of soil fast-acting nutrients can be accelerated, the soil microecological environment can be effectively improved, the root system of crops can be promoted to grow, the root system vitality and function can be enhanced, the absorption and utilization of water and nutrients by the crop root system can be improved, and the crop yield can be finally increased.

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

[0046] According to the present invention, the excavation depth of the water collection lake should ensure that the daily water level in the lake is controlled below the critical depth of groundwater, and 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 water collection 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 distance between two adjacent shallow grooves can be adjusted according to the salt discharge capacity of the single-side shallow groove. Preferably, the distance between two adjacent shallow grooves is 60-100 times the depth of the shallow groove.

[0049] According to the present invention, the number of deep trenches dug in the saline-alkali land to be improved is not particularly limited, and multiple deep trenches can be dug according to the area of ​​the saline-alkali land to be improved. In a specific embodiment provided by the present invention, the area surrounded by one deep trench and multiple shallow trenches dug in the saline-alkali land to be improved is taken as the minimum unit, and other areas are arranged in the same manner according to the design of the minimum unit. The inventors of the present invention have found that the smaller the spacing between the deep trenches is, the more conducive it is to lowering and controlling the daily groundwater level and preventing and controlling the occurrence of salinization.

[0050] According to the present invention, the distance between two adjacent deep grooves can be adjusted according to the salt discharge capacity of the single-side deep groove. Preferably, the distance between two adjacent deep grooves is 60-100 times the depth of the deep groove.

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

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

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

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

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

[0056] According to some embodiments of the present invention, a water level monitor and / or a water pump is further 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 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 time of water injection is preferably after the thawing of the frozen layer 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 the soil is moistened so that water accumulates in the furrows. For example, the water inlets and outlets of the shallow furrows and deep furrows can be blocked, and water can be injected into the furrows using a water pump.

[0060] Preferably, the water injection method includes injecting water into the ridge soil so that the water reaches 0.5-1m into the soil or water is discharged in a shallow ditch.

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

[0062] According to the present invention, the soil in saline-alkali land is severely compacted and has poor permeability. Deep plowing and rotary tillage of the soil can reconstruct the soil structure of the cultivated layer, improve the soil aggregate structure, and dilute the salt content of the cultivated layer soil, thereby creating a soil environment with a balance of "water, fertilizer, air, and heat".

[0063] According to the present invention, the method of deep tillage and rotary tillage is not particularly limited, for example, a tiller or rotary tiller may be used for the operation.

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

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

[0066] According to the present invention, the calculation method of soil alkalinity is shown in "LY / T 1249-1999 Calculation of soil alkalinity", soil alkalinity (%) = 100 × (exchangeable sodium ion content / cation exchange capacity); wherein, soil exchangeable sodium ion content and cation exchange capacity are measured according to the method of "NY / T 295-1995 Determination of cation exchange capacity and exchangeable base of neutral soil".

[0067] According to the present invention, soil porosity is measured by volume method, soil porosity (%) = 100% × (1-bulk density / specific gravity); wherein bulk density refers to the ratio of the weight of soil to the volume it occupies without destroying the soil structure; and specific gravity refers to the ratio of the volume actually 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 measured by a double ring method, and the specific operation process includes: taking an original soil sample with a ring cutter, immersing it in water, and then, under a unit water pressure gradient, according to Darcy's law, obtaining the water flow velocity per unit soil cross-sectional area perpendicular to the water flow direction.

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

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

[0071] (2) Planting crops on 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 the improved land, the soil moisture content of the tillage layer during the crop growth period is regulated to further promote the growth of the crops. 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 daily testing of the soil moisture content and timely replenishment of irrigation water or drainage so that the soil field water holding capacity is stably controlled at 15-20% by weight, thereby controlling the soil salt concentration, reducing salt and alkali damage, and maintaining normal crop growth.

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

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

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

[0078] Example 1

[0079] (1) Deep plowing and rotary tillage of saline-alkali land were performed using a powder ridge agricultural machine to reduce the soil particle size to 0.8 ± 0.2 cm;

[0080] (2) At 54600m 2 A deep trench and two shallow trenches were dug in the saline-alkali land to be improved. The shallow trench was connected to the deep trench, and the deep trench was connected to the water collection lake (area 2730m 2 ) is connected;

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

[0082] The highest groundwater level (h2) in the rainy season of the saline-alkali land to be improved is 1.2m, the underground stable water head difference (Δh2) is 0.1m, and the water level depth in the shallow ditch (h 02 ) is 0.1m, the bottom width of the shallow ditch (w2) is 0.5m, the slope coefficient (S2) is 1.5, the depth of the shallow ditch (L2) is 1.4m, the width of the shallow ditch (W2) is 4.7m, and the spacing is 140m;

[0083] (3) 150 ridges are dug between two adjacent shallow ditches, with a ridge width of 90 cm; the width of the ridge platform is 70 cm, and the height of the ridge platform is 30 cm; the width of the ridge ditch is 20 cm, and the depth of the ridge ditch is 30 cm; a vertical shaft is dug in the middle of the smallest rectangular saline-alkali land surrounded by two adjacent shallow ditches and the deep ditch, with a depth of 5 m and a diameter of 3 m;

[0084] (4) Pour water into the soil of the ridge platform until the water reaches 1m into the soil, then stop pouring water and let it stand to drain water naturally by infiltration;

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

[0086] Finally, the sunflower seed yield was measured to be 150kg / mu.

[0087] Example 2

[0088] (1) Deep plowing and rotary tillage of saline-alkali land were performed using a powder ridge agricultural machine to reduce the soil particle size to 0.8 ± 0.2 cm;

[0089] (2) At 189,000 m 2 A deep trench and four shallow trenches were dug in the saline-alkali land to be improved. The shallow trenches were connected to the deep trenches, and the deep trenches were connected to the water collection lake (area 9450m 2 ) is connected;

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

[0091] The highest groundwater level (h2) in the rainy season of the saline-alkali land to be improved is 1.2m, the underground stable water head difference (Δh2) is 0.1m, and the water level depth in the shallow ditch (h 02 ) is 0.1m, the width of the shallow ditch bottom (w2) is 0.5m, the slope coefficient (S2) is 1.5, the depth of the shallow ditch (L2) is 1.4m, the width of the shallow ditch (W2) is 4.7m, and the spacing is 120m;

[0092] (3) 165 ridges are dug between two adjacent shallow ditches, with a ridge width of 70 cm; the width of the ridge platform is 50 cm, and the height of the ridge platform is 30 cm; the width of the ridge ditch is 20 cm, and the depth of the ridge ditch is 30 cm; a vertical shaft is dug in the middle of the smallest rectangular saline-alkali land surrounded by two adjacent shallow ditches and the deep ditch, with a depth of 5 m and a diameter of 3 m;

[0093] (4) Pour water into the soil of the ridge platform until the water reaches 1m into the soil, then stop pouring water and let it stand to drain water naturally by infiltration;

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

[0095] Finally, the sunflower seed yield was measured to be 180kg / mu.

[0096] Example 3

[0097] The method of Example 2 is the same, except that the width of the ridge body is 90 cm, the width of the ridge platform is 70 cm, the height of the ridge platform is 10 cm, the width of the ridge furrow is 20 cm, and the depth is 10 cm;

[0098] Finally, the sunflower seed yield was measured to be 100kg / mu.

[0099] Comparative Example 1

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

[0101] Comparative Example 2

[0102] The method of Example 2 is as follows, except that the depth of the deep trench is 1.5 m, the depth of the shallow trench is 1.3 m, and the depth of the shaft is 2 m;

[0103] Finally, the sunflower seed yield was measured to be 80kg / mu.

[0104] Test Example 1

[0105] Before crop planting and after crop harvesting, the soil physical and chemical properties of the saline-alkali land in the embodiment and the comparative example were measured, and the results are shown in Table 1.

[0106] The pH value was measured using a pH meter.

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

[0108] Soil alkalinity (%) = 100 × (exchangeable sodium ion content / cation exchange capacity). The calculation method of alkalinity is shown in "LY / T 1249-1999 Calculation of soil alkalinity", where soil exchangeable sodium ion content and cation exchange capacity are determined according to the method of "NY / T 295-1995 Determination of cation exchange capacity and exchangeable base of neutral soil".

[0109] Soil porosity is measured by volume method, soil porosity (%) = 100% × (1-bulk density / specific gravity); bulk density refers to the ratio of the weight of soil to the volume it occupies without destroying the soil structure; specific gravity refers to the ratio of the volume actually occupied by soil solid particles to the weight of the same volume of water.

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

[0111] The abundance of microorganisms is determined by real-time fluorescence quantitative PCR, a method for quantitatively analyzing specific DNA sequences in the sample to be tested through internal or external reference methods.

[0112] Table 1

[0113]

[0114] It can be seen from the data of Example 1-2 in Table 1 that the pH, salinity and alkalinity of the saline-alkali soil before field planting after improvement are very high, soil porosity, permeability coefficient and microbial abundance are low, and the pH, salinity and alkalinity of the saline-alkali soil after field planting after improvement are all decreased, and soil porosity, permeability coefficient and microbial abundance are all improved, and the degree of soil salinization, soil structure and microecological environment are all effectively improved. It can be seen from this that the soil porosity, permeability coefficient, pH and alkalinity of saline-alkali land can be improved by the method of the present invention, and then the soil is promoted to form a good microecological environment, improve microbial abundance, and allow crops to grow normally in a good soil environment, and increase yield.

[0115] By comparing Example 2 with Example 3, it can be seen that the preferred method can further improve the soil structure, pH and microecological environment of saline-alkali land and increase yield.

[0116] In Comparative Example 1, no soil improvement was performed. Before planting, the soil was severely salinized, the soil was compacted, the air permeability was poor, and the microecological environment was poor. After planting crops, the soil salinization was more serious, the soil compaction was not improved, and the microecological environment was worse, resulting in a reduction in crop yield. In Comparative Example 2, the ratio between the depth of the deep ditch and the depth of the shallow ditch was reduced, the degree of soil salinization was aggravated, the soil became compacted, the air permeability became poor, and the microecological environment was not improved, resulting in a reduction in crop yield.

[0117] In summary, the method of the embodiment of the present invention can further improve the soil structure, pH and microecological environment of saline-alkali land and increase yield.

[0118] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for improving soil in soda saline-alkali land in seasonal frozen soil areas, characterized in that: The method includes: (1) A water collection lake, a deep ditch and multiple shallow ditches are excavated in the saline-alkali land to be improved, so that the multiple shallow ditches are connected to the deep ditch, the deep ditch is connected to the water collection lake, and the depth L1 of the deep ditch satisfies: L1 = h1 + Δh1 + h 01 ; where h1≥3m, Δh1 is the underground stable water head difference, in m; h 01 is the water level depth in the deep ditch, in meters; 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 trenches, wherein the ratio between the depth of the vertical shaft and the depth of the deep trench is 0.7-1.5; (3) Water is injected into the soil between the shallow trenches.

2. The method according to claim 1, wherein: The depth L1 of the deep groove satisfies: L1 = h1 + Δh1 + h 01 , h1 is 3.2-4.5m, Δh1 is 0.1-0.2m, h 01 0.1-0.2m; And / or, the method further comprises excavating a plurality of ridges between adjacent shallow trenches, wherein the ridges are parallel to the shallow trenches; Preferably, the ridge body consists of a ridge platform and a ridge ditch; Preferably, the width of the ridge body is 50-90 cm, and the spacing between ridge platforms is 15-20 cm; Preferably, the ratio of the width to the height of the ridge is (1.5-3.5):1; Preferably, the ratio of the width to the depth of the ridge is (0.5-1):

1.

3. The method according to claim 1, wherein: The area of ​​the water collection 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 grooves.

4. The method according to claim 1, wherein: The depth L2 of the shallow groove satisfies: L2 = h2 + Δh2 + h 02 ; Where, h2≥0.5m, Δh2 is the underground stable water head difference, in m; h 02 is the depth of water level in the shallow ditch, in m; Preferably, h2 is 0.8-1.2 m; Δh2 is 0.1-0.2 m; h 02 0.1-0.2m; And / or, the deep groove is vertically connected to the shallow groove.

5. The method according to any one of claims 1 to 4, wherein: The width W1 of the deep groove, the slope coefficient S1 of the deep groove, the bottom width w1 of the deep groove, and the depth L1 of the deep groove satisfy the relationship: W1=L1×S1×2+w1; And / or, the width W2 of the shallow groove, the slope coefficient S2 of the shallow groove, the groove bottom width w2 of the shallow groove, and the depth L2 of the shallow groove satisfy the relationship: W2=L2×S2×2+w2; Preferably, the slope coefficient S1 of the deep ditch is 1.5-2, and the ditch bottom width w1 of the deep ditch is 1-3m; the slope coefficient S2 of the shallow ditch is 1-1.5, and the ditch bottom width w2 of the shallow ditch is 0.5-1m.

6. The method according to claim 2, wherein: The depth of the vertical shaft is 3-5m and the diameter is 2-3m; Preferably, the water injection method includes injecting water into the soil of the ridge platform so that the water reaches 0.5-1m of the soil or water is discharged in the shallow ditch; Preferably, the method further comprises deep ploughing and rotary tillage of the soil before digging deep trenches and shallow trenches in the saline-alkali land to be improved, so that the soil particle size is within the range of 0.5-1 cm.

7. The method according to any one of claims 1 to 4, wherein: A water level monitor and / or a water pump are also provided in the shaft.

8. The method according to any one of claims 1 to 4, wherein: The saline-alkali land to be improved has a salt content of ≥6 g / kg, an alkalinity of ≥30%, a pH of 8.5-10.5, a permeability coefficient of 0.85-1.2 mm / min, and is clay loam.

9. A method for cultivating crops in soda saline-alkali land in seasonally frozen soil areas, characterized in that: The method includes: (1) improving the saline-alkali land to be improved according to the method according to any one of claims 1 to 8; (2) Planting crops on improved land.

10. The method according to claim 9, wherein: The crop is selected from at least one of sunflower, sugar beet and soybean.

Images