Ultra-stable mineralization in-situ salt fixation method for improvement of saline-alkali soil in arid region and application of ultra-stable mineralization in-situ salt fixation method

Abstract

The invention relates to the technical field of soil improvement and ecological restoration, and discloses an ultra-stable mineralization in-situ salt fixation method for improvement of saline-alkali soil in an arid region and application of the ultra-stable mineralization in-situ salt fixation method. The invention provides a method for improving northwest inland saline-alkali soil based on combination of an ultra-stable mineralized in-situ salt-fixing soil conditioner, precise partitioning, biological improvement and salt-tolerant plant planting. According to the method, a salt elimination foundation is created through physical soil preparation, firstly, the soil alkalization degree and the salt content are rapidly reduced through an ultra-stable mineralization in-situ salt fixation soil conditioner, the physical structure of the soil is improved, and then rapid salt elimination and alkali inhibition, fertility cultivation and ecological reconstruction of the saline-alkali soil are finally achieved by constructing different plant planting modes and establishing a stable vegetation system. And a sustainable saline-alkali soil comprehensive treatment mode with good effect and low cost is formed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil improvement and ecological restoration, and particularly relates to a super-stable mineralization in-situ salt fixation method for saline-alkali soil improvement in arid regions and application. BACKGROUND

[0002] The northwest inland areas of China (such as Xinjiang, Qinghai, Gansu, and the western part of Inner Mongolia) are located deep in the inland, have a dry climate, and have a much greater evaporation capacity than precipitation. The underground water is shallow and has a high degree of mineralization. The salt is largely accumulated on the surface with water evaporation, and a large area of saline-alkali land is formed. Among them, the extremely severe saline-alkali land with a total salt content of more than 1.0% (even as high as 2-3%) is widely distributed. The soil structure of this kind of land is extremely poor, the sodium ion content is high, the water permeability and air permeability are almost lost, and the natural vegetation is sparse or even has no plant. Not only is it a huge waste of land resources, but also it affects the surrounding ecological environment and human health through salt dust storms and other forms, and restricts the sustainable development of the region.

[0003] At present, the salt is controlled by engineering irrigation and drainage measures. However, due to the high salt content and insufficient water in the northwest severe saline-alkali wasteland, the engineering quantity of such measures is large, the cost is high, and only the spatial distribution of salt can be changed or the surface salt can be inhibited, which cannot fundamentally solve the problem of soil alkalization and is easy to repeat. The chemical improvement of desulfurized gypsum, sulfur and the use of waste biomass materials has a significant effect on reducing alkali and salt, improving microbial activity and promoting plant growth and development. However, the application objects of the above technologies are mostly based on saline-alkali farmland, and it is difficult to meet the soil requirements of the severe saline-alkali wasteland in the northwest arid region. Biological improvement can also be carried out through the ways of salt absorption by plants, root improvement of soil structure, and microbial activation of nutrients. This method is environmentally friendly and low in cost, but for extremely severe saline-alkali land, the survival rate of direct planting of plants is extremely low, the improvement speed is slow, and it is difficult to take effect in a short period of time.

[0004] In summary, the existing technologies are mostly the use of single method or simple combination, and it is difficult to achieve rapid, stable, long-term and economically feasible improvement for the complex problems of "salt, alkali, board, and thin" coexisting in the extremely severe saline-alkali land in the northwest inland. Therefore, it is urgent to develop a comprehensive improvement method based on super-stable mineralization for rapid salt fixation, which can solve multiple obstacle factors. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art, and provides a super-stable mineralization in-situ salt fixation method for saline-alkali soil improvement in arid regions and application.

[0006] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a super-stable mineralization in-situ salt fixation soil improver for saline-alkali soil improvement in arid regions, wherein the super-stable mineralization in-situ salt fixation soil improver comprises the following components: a mineral source component, an organic source component and a biological source component. The mineral source component comprises a calcium source and an iron source.

[0007] The second aspect of the present application provides an application of the super-stable mineralization in-situ salt-fixing soil amendment according to the first aspect in the improvement of saline-alkali soil in arid regions.

[0008] The third aspect of the present application provides a method for improving saline-alkali soil in arid regions by using the super-stable mineralization in-situ salt-fixing soil amendment according to the first aspect, wherein the method comprises mixing each component of the super-stable mineralization in-situ salt-fixing soil amendment with the saline-alkali soil to be improved for soil improvement.

[0009] The method is a rapid, efficient and durable ecological restoration method for saline-alkali land by combining super-stable mineralization in-situ salt-fixing, biological improvement and planting of salt-tolerant plants.

[0010] Through the above technical solution, the present application has the following beneficial technical effects: (1) The present application realizes salt fixation by using the super-stable mineralization salt-fixing soil amendment: the Fe 2+ and other ore-forming missing elements provided by the amendment react with the salt ions in the soil, and through the process of being fixed into the newly generated mineral lattice, the salt in the soil is converted into stable mineral phase in situ; the functional microorganisms continuously activate the soil and promote aggregation; the amendment can be used to improve the saline-alkali soil in arid regions, and the improvement is rapid and the effect is durable.

[0011] (2) The present application also provides a method for improving saline-alkali land in the northwest inland based on the super-stable mineralization in-situ salt-fixing soil amendment, precise partitioning, biological improvement and planting of salt-tolerant plants. The method creates a salt discharge basis through physical land preparation, first rapidly reduces the soil alkalinity and salt content by using the super-stable mineralization in-situ salt-fixing soil amendment, and improves the soil physical structure, then constructs different plant planting modes, and establishes a stable vegetation system, finally realizes rapid desalination and alkali inhibition of the saline-alkali land, cultivates the fertility and reconstructs the ecology, and forms a comprehensive saline-alkali land management mode with good effect, low cost and sustainability. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is the overall technical flow chart of the super-stable mineralization in-situ salt-fixing and ecological restoration of saline-alkali land according to the present application.

[0013] Figure 2 is a schematic diagram of four kinds of compound planting modes.

[0014] Figure 3 is the corn emergence effect of each treatment group of the improved soil sample in Yakeshounuti Village, Xinjiang.

[0015] Figure 4 is the corn emergence effect of each treatment group of the improved soil sample in Yingtu'er Village, Xinjiang.

[0016] Figure 5 is the corn emergence effect of Xinjiang Wuzun Town Yingni and Village soil sample modification Z1-Z3 treatment group.

[0017] Figure 6 is the corn emergence effect of Xinjiang Wuzun Town Yingni and Village soil sample modification Z4-Z6 treatment group.

[0018] Figure 7 is the corn emergence effect of Xinjiang Wuzun Town Yingni and Village soil sample modification Z7-Z9 treatment group.

[0019] Figure 8 is the on-site modification effect of Gansu Jingtai saline-alkali wasteland. DETAILED DESCRIPTION

[0020] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the invention. The endpoints of the ranges and any numerical values should be interpreted as approximately including values near the reported values. For numerical ranges, the endpoints are included in the ranges. The disclosure of ranges includes endpoints.

[0021] The first aspect of the present application provides an ultra-stable mineralized in-situ salt-fixing soil modifier for saline-alkali soil modification in arid regions, wherein the soil modifier comprises the following components: a mineral source component, an organic source component and a biological source component. The mineral source component comprises a calcium source and an iron source.

[0022] In the modifier, the mineral source component provides abundant Ca 2+ , which replaces the exchangeable Na + in the soil colloid, effectively reducing the degree of soil salinization; at the same time, the supplemented iron element promotes the in-situ formation of LDH-like natural mineral phases in the soil, thereby synergistically reducing the soil alkalinity and pH value.

[0023] In some embodiments of the present application, the calcium source is selected from at least one of calcium-based montmorillonite, phosphogypsum and calcium-based bentonite.

[0024] In some embodiments of the present application, the iron source is selected from at least one of ferrous sulfate and iron disulfide.

[0025] In some embodiments of the present application, the weight fraction of the calcium source is 30-50 parts, for example, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, etc., and any value within the range of any two of the above.

[0026] In some embodiments of the present application, the weight fraction of the iron source is 30-50 parts, such as 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, and any value within the range between any two of the above-mentioned values.

[0027] In some embodiments of the present application, the mineral source component further comprises at least one of vermiculite and attapulgite.

[0028] In some embodiments of the present application, the weight fraction of the vermiculite is 10-25 parts, such as 10 parts, 15 parts, 20 parts, 25 parts, and any value within the range between any two of the above-mentioned values.

[0029] In some embodiments of the present application, the weight fraction of the attapulgite is 10-30 parts, such as 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, and any value within the range between any two of the above-mentioned values.

[0030] In some embodiments of the present application, the organic source component is selected from at least one of humic acid, crop straw, and organic fertilizer.

[0031] In the organic source component, the humic acid plays its ion exchange and buffering performance, assists in replacing Na + and complexing heavy metals, and activates soil microbial activity; the crop straw and the organic fertilizer provide carbon source and energy for soil microorganisms, promote microbial reproduction, and improve soil aggregate structure.

[0032] In some embodiments of the present application, the weight fraction of the humic acid is 10-20 parts, such as 10 parts, 15 parts, 20 parts, and any value within the range between any two of the above-mentioned values.

[0033] In some embodiments of the present application, the weight fraction of the crop straw is 10-30 parts, such as 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, and any value within the range between any two of the above-mentioned values.

[0034] In some embodiments of the present application, the weight fraction of the organic fertilizer is 10-30 parts, such as 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, and any value within the range between any two of the above-mentioned values.

[0035] In some embodiments of the present application, the crop straw is wheat straw.

[0036] In some embodiments of the present application, the organic fertilizer is rotten cow dung.

[0037] In some embodiments of the present application, the biological component is a functional microbial agent. The functional microbial agent in the biological component can adapt to the saline-alkali stress environment, synergize with the aforementioned mineral and organic components, and enhance the stability of the soil micro-ecosystem and the efficiency of mineralization and salt fixation.

[0038] In some embodiments of the present application, the functional microbial agent is in a weight fraction of 5-10 parts, such as 5 parts, 8 parts, 10 parts, and any value within the range of any two of the aforementioned values.

[0039] In some embodiments of the present application, the functional microbial agent is a Bacillus subtilis agent and / or arbuscular mycorrhizal fungus agent.

[0040] In some embodiments of the present application, the effective viable count of the core strain in the functional microbial agent is not less than 2.0 x 10 9 CFU / g. The core strain refers to Bacillus subtilis and / or arbuscular mycorrhizal fungus.

[0041] The second aspect of the present application provides an application of the super-stable mineralization in-situ salt fixation soil conditioner according to the first aspect in the improvement of saline-alkali soil in arid regions.

[0042] In some embodiments of the present application, the application amount of the soil conditioner is 1-2% of the weight of the soil to be improved, preferably 1.5%.

[0043] After mixing the conditioner with the soil to be improved, the soil is first wetted with an aqueous citric acid solution, and then water is added to make the water content of the soil reach about 50% (e.g., 40-70%) after a period of time (e.g., 7 days).

[0044] The third aspect of the present application provides a method for improving saline-alkali soil in arid regions using the super-stable mineralization in-situ salt fixation soil conditioner according to the first aspect, wherein the method comprises mixing the components of the super-stable mineralization in-situ salt fixation soil conditioner with the saline-alkali soil to be improved for soil improvement.

[0045] In some embodiments of the present application, the method comprises the following steps: (1) deep plowing the area to be improved, and then mixing the organic base fertilizer with the saline-alkali soil to be improved; (2) mixing the components of the super-stable mineralization in-situ salt fixation soil conditioner with the saline-alkali soil to be improved; (3) irrigating with irrigation water containing citric acid, and then using pure irrigation water to further promote the mineralization reaction and elute the residual salt after the soil surface is dry; (4) planting plants on high ridges when the soil moisture reaches 60-70%; (5) Continuous monitoring of soil salt, nutrients and vegetation changes, and subsequent introduction of more species to further improve and sustainably use saline-alkali land.

[0046] In some embodiments of the present application, step (1) is physical land preparation and micro-domain field construction. The specific operation can be as follows: use a subsoiler to subsoil at a depth of 30-50 cm, completely break the hard plough pan, and improve the infiltration performance and air permeability of the soil; after subsoiling, evenly spread 50-80 kg of organic base fertilizer (matured cow dung, straw compost, mushroom residue, etc.) per 100 m 2 The surface is evenly spread with 50-80 kg of organic base fertilizer (matured cow dung, straw compost, mushroom residue, etc.), and mixed with 0-20 cm surface soil by rotary tillage or manual plowing. Through mechanized physical land preparation, small-scale water and salt regulation units are constructed to achieve balanced soil water and salt distribution and optimized tillage levels.

[0047] In step (2), after uniformly spreading each component of the mineralized solid salt soil conditioner, immediately use manual, rotary tiller or disc harrow to mix the conditioner with the 0-20 cm soil layer.

[0048] In some embodiments of the present application, the method further comprises: before step (1), dividing the area to be improved into multiple grid units, exploring the salt distribution, selecting representative point soil samples within the grid for analysis and determination; in step (2), according to the saline soil classification system of the USDA Soil Salinity Laboratory (The USDA Soil Salinity Laboratory, Richards L A. Diagnosis and improvement of saline and alkaline soils. Agriculture Handbook No. 60. Washington, DC: US Department of Agriculture, 1954.), combined with the sampling and determination results, dividing the soil unit area of different soil types and different grades, and applying different amounts of mineralized solid salt soil conditioner.

[0049] In the present application, precise surveying and zoning design are carried out before step (1). The specific operation can be as follows: Firstly, the area to be improved is surveyed in detail. Using GPS and GIS technology, the area is divided into 2m*2m, 5m*5m or 10m*10m grid units (select the appropriate division unit according to the area of the improved area). Portable conductivity meter or electromagnetic induction instrument is used for mobile measurement, and apparent soil electrical conductivity (EC) data of large area is quickly obtained to preliminarily judge the degree and distribution of regional salinization. On this basis, representative points are selected in each grid, and 0-20cm surface soil samples are collected, and the total salt content (TSS), pH value and Na + , K + , Ca 2+ , Mg 2+ , HCO3 - , CO3 2- , Cl - , SO4 2- ion composition are determined in the laboratory. According to the United States Saline Soil Classification Standard, combined with the determination results, the improved area is divided into different grade sub-unit areas.

[0050] Table 1 Grade characteristics of saline-alkali soil sub-unit according to the saline soil classification system of the USDA Soil Salinity Laboratory ; Note: The conductivity is the measured value at 25℃; the judged saline-alkali soil type and its classification is in the period of soil sample determination.

[0051] The calculation formula of ESP (percentage of exchangeable sodium) is: ESP (%) = 100 x (-0.0126 + 0.01475SAR) / [1 + (-0.0126 + 0.01475SAR)].

[0052] The calculation formula of S AR (sodium adsorption ratio) is: SAR = [Na + ] / ([Ca 2+ ]+[Mg 2+ ]) 1 / 2 Wherein, [Na + ] is the concentration of soluble sodium ions in the soil sample, in units of millimoles per liter (mmol / L); [Ca 2+ ] is the concentration of soluble calcium ions in the soil sample, in units of millimoles per liter (mmol / L); [Mg 2+ ] is the concentration of soluble magnesium ions in the soil sample, in units of millimoles per liter (mmol / L).

[0053] According to different grades of regions, the application amount of the mineralized solid salt improvement agent in the subsequent steps is accurately calculated, and different salt-tolerant plant configuration modes are designed, so that resource saving and the accurate improvement of "one strategy for one region" are realized.

[0054] In some embodiments of the application, for sodic soil, when the sodium adsorption ratio is 15-20, the application amount is 400-450 kg per mu; when the sodium adsorption ratio is 20-30, the application amount is 600-650 kg per mu; and when the sodium adsorption ratio is > 30, the application amount is 900-1000 kg per mu.

[0055] In some embodiments of the application, for salinization-sodic soil, when the salinization degree is slight, the application amount is 200-250 kg per mu; when the salinization degree is moderate, the application amount is 250-350 kg per mu; and when the salinization degree is severe and extremely severe, the application amount is 500-800 kg per mu.

[0056] In some embodiments of the application, for saline soil, when the salinization degree is slight, the application amount is 150-250 kg per mu; when the salinization degree is moderate, the application amount is 300-400 kg per mu; and when the salinization degree is severe and extremely severe, the application amount is 600-800 kg per mu.

[0057] In some embodiments of the application, step (3) is water-saving and salt control. The specific operation can be as follows: after the super-stable mineralized in-situ solid salt soil improvement agent is uniformly applied, appropriate watering is immediately performed according to the area of the repaired soil, and if the area is large, a drip irrigation or micro-sprinkling irrigation system is installed. The operation is performed in two stages: The first stage: using "improved water" for irrigation. A small amount of citric acid is added to the irrigation water to adjust the pH to 6.5-7.0 of slightly acidic water. The irrigation amount is controlled at 15-20 m 3 / mu, so that the soil profile is fully wetted and the replacement reaction is promoted to occur; The second stage: interval 7-10 days, after the soil surface is slightly dry, this time ordinary irrigation water is used, and the irrigation amount is 10-15 m 3 / mu, further promoting the mineralization reaction, washing out the residual salt, and bringing Ca 2+ and other beneficial ions into deeper soil layers to avoid water resource waste and soil structure damage caused by traditional flood irrigation.

[0058] In some embodiments of the application, step (4) is crop screening and compound planting. After overall irrigation, 7-14 days later, when the soil humidity reaches 60-70%, the plant high ridge planting can be performed.

[0059] The plant high ridge planting adopts one of the following planting modes: arbor-shrub-herb, herb-green manure crop-economic crop, arbor-economic crop-green manure crop, shrub-herb-economic crop, preferably herb-green manure crop-economic crop. The above-mentioned compound planting mode can establish a clear hierarchical vegetation and increase biological diversity.

[0060] The present application specifically illustrates the planting mode as follows: Mode one: "arbor-shrub-herb" compound mode Plant combination: arbor: tamarix; shrub: halogeton glomeratus or nitraria sibirica; herb: suaeda salsa; planting layout: arbor row spacing 5-8 meters; shrub around arbor spacing 1-2 meters; herb covers the ground between arbor and shrub rows.

[0061] Advantages: deep-rooted arbor absorbs underground salt and fixes soil structure; shrub forms a windbreak to reduce wind erosion and topsoil loss; herb covers the soil surface, absorbs and discharges salt, and increases organic matter to improve soil structure.

[0062] Mode two: "herb-green manure crop-economic crop" compound mode Plant combination: herb: suaeda salsa; green manure crop: sesbania or alfalfa; economic crop: corn or oil sunflower; planting layout: herb covers the slope and the space between rows; green manure crop is rotated or intercropped between economic crop rows; economic crop is the main harvested crop.

[0063] Advantages: green manure crop fixes nitrogen, increases organic matter, and improves soil structure; shallow-rooted suaeda salsa absorbs surface salt; corn and oil sunflower can provide economic benefits and reduce treatment costs.

[0064] Mode three: "arbor-economic crop-green manure crop" compound mode Plant combination: arbor: tamarix; economic crop: sorghum or wild barley; green manure crop: alfalfa; planting layout: wide row spacing (5-7 meters) between arbor rows; green manure is intercropped between economic crop rows.

[0065] Advantages: arbor deep root absorbs salt and improves underground soil; sorghum and wild barley can be used for feed or food production; green manure crop increases soil organic matter and improves structure; arbor and green manure root systems complement each other to improve soil water use efficiency.

[0066] Mode four: "shrub-herb-economic crop" compound mode Plant combination: shrub: nitraria sibirica or halogeton glomeratus; herb: suaeda salsa; economic crop: corn or oil sunflower; planting layout: herb covers the empty space and the space between rows; economic crop is interspersed.

[0067] Advantages: shrubs form a barrier to reduce wind erosion and salt accumulation; herbaceous plants absorb surface salt and protect the roots of economic crops; corn and sunflower provide income while growing in improved soil; shrubs and herbs compound coverage, increase the ground vegetation level, and reduce the salt-alkali bare land.

[0068] In the present application, perennial salt-tolerant and drought-tolerant plants or crops that are locally adapted are preferred. For example, trees (deep-rooted, alkali-resistant and salt-resistant): tamarix; shrubs (drought-resistant, sand-fixing, wind-protecting and soil-protecting): haloxylon ammodendron or nitraria sibirica; herbs (shallow-rooted, soil-covering, salt-absorbing and soil-improving): suaeda salsa; economic crops (considering both income and soil improvement): at least one of sunflower, corn, wild barley and sorghum; green manure crops (soil improvement): at least one of sesbania cannabina and alfalfa.

[0069] In some embodiments of the present application, step (5) is to monitor the management and ecological succession. With the improvement of the soil environment, more ecologically and economically valuable species (such as wolfberry, elaeagnus angustifolia, alfalfa, etc.) can be artificially introduced or naturally invaded, guiding the ecological system to successively evolve from the pioneer community to a more complex and stable climax community, and ultimately realizing the complete improvement and sustainable utilization of the saline-alkali land.

[0070] The method for improving saline-alkali soil in a dry region by using the in-situ salt-fixing soil improver provided by the present application has the following advantages: (1) Strong systematicness and multi-technology integration: survey, engineering, chemistry, biology and agronomic measures are organically combined to form a complete technical chain for the four problems of "salt, alkali, board and thin" of extremely severe saline-alkali land, solving the limitations of single technology effect.

[0071] (2) Water and energy saving and environment friendly: artificial and drip irrigation are adopted, and the water consumption is reduced by 30-50% compared with traditional flooding irrigation; agricultural waste is used to reduce costs and avoid secondary pollution.

[0072] (3) Equal emphasis on ecological and economic benefits: through the construction of a compound vegetation system, not only the ecology is restored, but also certain economic benefits can be generated through the harvesting of salt-tolerant forage and sunflower economic crops.

[0073] (4) Wide adaptability: the core idea of the method is universal, and specific parameters (such as the amount of the improver, the amount of leaching water and the types of plants) can be flexibly adjusted according to the specific soil and climate conditions of different regions, and the method has great popularization potential in the saline-alkali regions of the vast northwest inland of China.

[0074] The present application will be described in detail through the following examples.

[0075] The following examples and comparative examples are not specified conditions, in accordance with conventional conditions or manufacturer's recommended conditions. The reagents or instruments used are not specified manufacturer, are conventional products that can be obtained by commercial channels.

[0076] Material sources: .

[0077] Application Example 1 This application example is used to illustrate the effect of different super-stable mineralization in-situ salt-fixing soil improver on soil improvement.

[0078] The soil sample was collected in Yakexiannuti Village, Kuche City, Aksu Region, Xinjiang Uygur Autonomous Region. The collection site is located in the northern margin of the Tarim Basin in the hinterland of the Eurasian continent, belonging to the typical temperate continental desert climate. According to the soil determination results, the average total salt content (TSS) of 0-20 cm soil layer is 2.504%, ECe is 6.58 dS / m, ESP is 4.91%, and pH is 8.36. According to the salt-affected soil classification system of the USDA Soil Salinity Laboratory, it belongs to moderate salinity soil.

[0079] Table 2 Soil sampling and determination results .

[0080] After soil determination, the super-stable mineralization in-situ salt-fixing soil improver formula improvement experiment was carried out, and the main experimental treatment group combination design is as follows: Table 3 Mineralization salt-fixing soil improver formula combination (calculated according to the proportion of 100 total amount) .

[0081] Implementation process: 2% of the improver is added to 100g of soil to be treated, mixed evenly, then 0.5mg / L of citric acid irrigation liquid (pH 6.8) is used to wet the soil, and the soil is placed for 7d; then, deionized water is used to keep the soil moisture content at about 50%, and a corn seed germination experiment is carried out. 2 corn seeds are planted for each treatment, and the emergence effect is observed in time under natural light conditions.

[0082] Figure 3 The results show that after one week of experiment, the K2 treatment group successfully emerged, the K1 and K3 treatment groups appeared bud points, but compared with the K2 treatment, the emergence was slow, and the CK-A group did not emerge.

[0083] Application Example 2 This application example is used to illustrate the effect of different super-stable mineralization in-situ salt-fixing soil improver on soil improvement.

[0084] The soil sample was collected in Yingtuer village, Kuqa city, Aksu region, Xinjiang Uygur autonomous region. A total of 3 points were collected, the total salt content (TSS) of 0-20 cm soil layer was 1.7-2.0%, ECe was 5.11-5.35 dS / m, ESP was 3.10%-8.19%, and pH was about 8.0. According to the soil determination results, according to the salinized soil classification system of the United States Department of Agriculture Salinity Laboratory, the collection area belongs to medium and heavy saline soil type.

[0085] Table 4 Determination results of point sampling .

[0086] Table 5 Added mineralized solid salt improvement agent formula combination (calculated according to the proportion of 100 parts of total amount) .

[0087] The implementation process: according to the method of application example 1, the difference is that 1.5% of the improvement agent is added to 100g of soil, and the pH of the 0.5mg / L citric acid irrigation liquid used is 6.54.

[0088] Figure 4 The results show that, after one week of experiment, compared with the control, the Y3 treatment group successfully germinated, and the germination effect was better.

[0089] Application example 3 This application example is used to illustrate the effect of different super-stable mineralized in-situ solid salt soil improvement agents on soil improvement.

[0090] The soil sample was collected in Yingnihe village, Wuzun town, Kuqa city, Aksu region, Xinjiang Uygur autonomous region. A total of 3 points were collected, the average total salt content (TSS) of 0-20 cm soil layer was 1.3-1.6%, ECe was 4.78-5.35 dS / m, ESP was 3.01%-5.28%, and pH was about 8.0. According to the soil determination results, according to the salinized soil classification system of the United States Department of Agriculture Salinity Laboratory, it belongs to medium saline soil.

[0091] Table 6 Determination results of point sampling .

[0092] Table 7 Added mineralized solid salt improvement agent formula combination (calculated according to the proportion of 100 parts of total amount) .

[0093] Implementation process: according to the method of application example 1, add 1% of the modifier to 100g soil, use 0.5mg / L citric acid irrigation liquid with pH of 6.91.

[0094] Figure 5 The results show that after one week of experiment, compared with the control, each treatment group did not emerge, and the improvement effect was limited.

[0095] Figure 6 The results show that after one week of experiment, compared with the control, Z4 and Z5 treatment groups successfully emerged, and the emergence effect was better.

[0096] Figure 7 The results show that after one week of experiment, compared with the control, Z7, Z8 and Z9 treatment groups successfully emerged, and the emergence effect was better.

[0097] Application example 4 This application example is used to illustrate the method for improving saline-alkali soil in arid areas by using in-situ salt solidification of super-stable mineralization soil modifier.

[0098] (1) Project area profile: Located in the extremely severe saline-alkali wasteland of Jingtai County, Baiyin City, Gansu Province, it is located in the transition zone between the Loess Plateau and the Tengger Desert. The climate of this land is dry, the annual evaporation is about 16 times the precipitation, the water deficit is serious, the salt is easy to rise and accumulate in the surface layer, the soil is sandy saline-sodic soil, the average total salt content (TSS) of 0-20cm soil layer is >2%, the pH is between 8-10, the organic matter content is <0.5%, and there is almost no vegetation.

[0099] (2) Implementation process: S1. Precise survey and zoning: 100m 2 The test field is divided into 4 grids of 5m*5m. The portable electromagnetic induction conductivity meter survey shows that the salt distribution is uneven, and the northeast corner is the highest. After sampling and determination, combined with the American saline soil classification standard, 35m 2 of the 100m 2 land is divided into "severe area" (TSS: 3.34%; ECe: 10.12dS / m; SAR: 32.54503; ESP: 31.85%), 35m 2 is divided into "moderate area" (TSS: 2.43%; ECe: 8.07dS / m; SAR: 28.8199; ESP: 29.20%), and 30m 2 is divided into "moderate area" (TSS: 1.94%; ECe: 6.99dS / m; SAR: 18.18732; ESP: 20.36%).

[0100] Table 8 Point sampling and determination results .

[0101] S2. Physical land preparation: 40cm deep ploughing was carried out. After deep ploughing, 80kg of organic base fertilizer of cow manure was evenly applied to the surface of the land, and mixed with the 0-20cm surface soil by manual ploughing. 2

[0102] S3. Application of mineralized salt-fixing soil amendment: The super-stable mineralized in-situ salt-fixing soil amendment includes the following components: calcium-based montmorillonite 30 parts; ferrous sulfate 30 parts; attapulgite 30 parts; humic acid 10 parts; wheat straw 15 parts; Bacillus subtilis inoculant 5 parts.

[0103] For "extremely severe areas", 120kg of mineralized salt-fixing amendment was applied; for "super severe areas", 90kg was applied; for "severe areas", 60kg was applied. After application with a fertilizer spreader, rotary tillage was carried out to a depth of 20cm.

[0104] S4. Water-saving irrigation: First stage: irrigation with "improved water". 0.5 mg / L of citric acid was added to the irrigation water to adjust the pH to 6.5-7.0 of slightly acidic water. The total irrigation amount was controlled at 1.5m 3 , to fully wet the soil profile. After leaching irrigation, a smooth mineralization of 10d was carried out, and the second stage was entered.

[0105] Second stage: using ordinary irrigation water, the total irrigation amount was 0.75m 3 .

[0106] S5. Planting plants: Ten days after overall irrigation, when the soil moisture was 60%, ridging was carried out; a total of 13 ridges were formed, with a ridge length of 7m, a ridge width of 60cm, and a ridge height of 15cm, using a "herbaceous-green manure crop-economic crop" composite mode for cross planting.

[0107] Field bean seeds were selected, dibbled, with a plant spacing of 20cm x 20cm; corn seeds were dibbled, with a plant spacing of 20cm x 20cm; sunflower seeds were dibbled, with a row spacing of 30cm x 30cm; and Suaeda salsa seeds were broadcasted, sown in the ridge side and ridge ditch area.

[0108] S6. Management and effect monitoring: timely observation of seedling emergence and improvement effect.

[0109] Table 9 Changes in soil salt content indicators in different months .

[0110] Figure 8 The on-site improvement effect is shown. ​

[0111] In late June of the same year, the improvement was completed, and in July of the same year after the improvement: in general, the survival rate of corn in each improved area was 90%, the emergence rate of oil sunflower was 70%, the coverage of sesbania was 50%, and the coverage of halocnemum strobilaceum was 70%. The TSS of the soil in the 0-20cm soil layer was reduced to about 1.65%, the pH was reduced to about 8.2, and the SAR was reduced to 15-18. The soil salinity was reduced, the soil was gradually loosened, and the hardening was reduced.

[0112] In August of the same year after the improvement: in general, the growth state of plants in each improved area was good, the TSS was reduced to about 1.30%, the pH was reduced to about 8.0, the SAR was reduced to 10-14, and the soil gradually formed a granular structure.

[0113] In September of the same year after the improvement: the vegetation community was more dense, although the temperature in the northwest decreased rapidly, the plants gradually withered, but the soil indicators continued to improve, the TSS was reduced to about 1.0%, the pH was reduced to about 7.95, except that the SAR value in the extremely severe area had no obvious change compared with the previous month, the SAR in the severe area and the moderate-severe area was reduced to 9.54 and 11.17 respectively, reaching the improvement effect of greatly reducing salt damage, and it was found that other grass species naturally invaded the improved area, the ecological system tended to be stable, and had the potential to plant more economic crops.

[0114] The preferred embodiments of the application are described in detail above, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the application and belong to the protection scope of the application.

Claims

1. A super-stable mineralized in-situ salt-fixing soil conditioner for improving saline-alkali soil in arid areas, characterized in that, The soil conditioner comprises the following components: mineral-based components, organic-based components, and biological-based components; The mineral source components include both calcium and iron sources.

2. The ultra-stable mineralized in-situ salt-fixing soil conditioner according to claim 1, wherein, The calcium source is selected from at least one of calcium-based montmorillonite, phosphogypsum, and calcium-based bentonite. Preferably, the iron source is selected from at least one of ferrous sulfate and ferric disulfide; Preferably, the calcium source is 30-50 parts by weight; Preferably, the iron source is 30-50 parts by weight.

3. The ultra-stable mineralized in-situ salt-fixing soil conditioner according to claim 2, wherein, The mineral source component also includes at least one of vermiculite and attapulgite; Preferably, the vermiculite is present in 10-20 parts by weight; Preferably, the weight of the attapulgite is 10-30 parts.

4. The superstable mineralized in-situ salt-fixing soil conditioner according to any one of claims 1-3, wherein, The organic source component is selected from at least one of humic acid, crop straw and organic fertilizer; Preferably, the humic acid is present in 10-25 parts by weight; Preferably, the crop straw is in the form of 10-30 parts by weight; Preferably, the organic fertilizer is 10-30 parts by weight; Preferably, the crop straw is wheat straw; Preferably, the organic fertilizer is well-rotted cow manure.

5. The super-stable mineralized in-situ salt-fixing soil conditioner according to any one of claims 1-4, wherein, The biological source component is a functional microbial agent; Preferably, the functional microbial agent is present in 5-10 parts by weight; Preferably, the functional microbial agent is a Bacillus subtilis agent and / or an arbuscular mycorrhizal fungal agent; Preferably, the effective viable count of the core strain in the functional microbial agent is not less than 2.0 × 10⁻⁶. 9 CFU / g.

6. The application of the super-stable mineralized in-situ salt-fixing soil conditioner according to any one of claims 1-5 in the improvement of saline-alkali soil in arid areas; Preferably, the soil conditioner is applied at a rate of 1-2% of the weight of the soil to be improved, more preferably 1.5%.

7. A method for improving saline-alkali soil in arid areas using the ultra-stable mineralized in-situ salt-fixing soil conditioner according to any one of claims 1-5, characterized in that, The method includes: mixing the components of the super-stable mineralized in-situ salt-fixing soil conditioner with the saline-alkali soil to be improved for soil improvement.

8. The method according to claim 7, wherein, The method includes the following steps: (1) Deep tillage is carried out on the area to be improved, and then organic base fertilizer is mixed with the saline-alkali soil to be improved; (2) Mix the components of the super-stable mineralized in-situ salt-fixing soil conditioner with the saline-alkali soil to be improved; (3) Use irrigation water containing citric acid for irrigation, and after the soil surface dries, use pure irrigation water to further promote the mineralization reaction and wash away residual salts. (4) Plant the plants on raised beds when the soil moisture reaches 60-70%; (5) Continuously monitor changes in soil salinity, nutrients and vegetation, and introduce more species to further improve and sustainably utilize saline-alkali land.

9. The method according to claim 7 or 8, wherein, The method further includes: before step (1), dividing the area to be improved into multiple grid units, conducting salt distribution exploration, selecting representative soil samples within the grid, and conducting analysis and measurement; in step (2), based on the USDA Salinity Laboratory's saline soil classification system and combined with the sampling and measurement results, dividing different soil types and different levels of sub-units, and applying different amounts of ultra-stable mineralized in-situ salt-fixing soil conditioner. Preferably, for sodium-rich soil, the application rate is 400-450 kg / mu when the sodium adsorption ratio is 15-20; 600-650 kg / mu when the sodium adsorption ratio is 20-30; and 900-1000 kg / mu when the sodium adsorption ratio is >30. Preferably, for saline-sodium soils, the application rate is 200-250 kg / mu when the salinization degree is mild; 250-350 kg / mu when the salinization degree is moderate; and 500-800 kg / mu when the salinization degree is severe or extremely severe. Preferably, for saline soil, the application rate is 150-250 kg / mu when the salinization degree is mild; 300-400 kg / mu when the salinization degree is moderate; and 600-800 kg / mu when the salinization degree is severe or extremely severe.

10. The method according to any one of claims 7-9, wherein, The plant ridge planting in step (4) adopts one of the following planting patterns: tree-shrub-herb, herb-green manure crop-economic crop, tree-economic crop-green manure crop, shrub-herb-economic crop, preferably herb-green manure crop-economic crop; Preferably, the tree is tamarisk; Preferably, the shrub is selected from at least one of *Salvia splendens* and *Nitraria tangutorum*; Preferably, the herb is Suaeda salsa; Preferably, the cash crop is selected from at least one of sunflower, corn, wild barley and sorghum; Preferably, the green manure crop is selected from at least one of sesbania and alfalfa.

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