Method for improving coal mine acid soil in northern grassland region

Abstract

The application discloses a method for improving coal mine acidic soil in northern grassland area, which comprises the following steps: firstly, dividing the original soil into two layers, i.e., a reduction neutral surface soil layer and a reduction barrier layer; secondly, excavating the original soil from top to bottom to form an excavation area, mixing the excavated soil with an acidic improver to form improved surface soil; thirdly, laying the reduction barrier layer at the bottom of the excavation area, which is made of reduction material and clay particles; and finally, backfilling the improved surface soil to generate acid-base conditions suitable for the growth of acid-resistant plants. The method can effectively reduce the acidity of the coal mine soil in the northern grassland area through the physical-chemical-biological interaction mechanism.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of acid soil improvement, in particular to a method for improving coal mine acid soil in northern grassland area. BACKGROUND

[0002] At present, most of the researches on acid coal mine are concentrated in southern area, and the researches on how to repair acid soil under cold conditions in northern area are less. In coal mines containing a large amount of sulfur-containing minerals, the sulfur-containing minerals will catalyze and oxidize into Fe2+ and SO42- under the action of water and oxygen, and acid will be generated in the oxidation process. Fe2+ is further oxidized to Fe3+, and the pH is further reduced. When the environmental acidity increases, the effective concentration of Al3+ and Fe2+ in the soil increases rapidly, and the excess metal cations induce the formation of active oxygen free radicals, which seriously interfere with the normal material metabolism in the plant body, and interfere and destroy the cell structure and function, becoming a limiting factor for plant growth. SUMMARY

[0003] The purpose of the present application is to provide a method for improving coal mine acid soil in northern grassland area, to improve the site conditions of plants by applying reducing substances and alkaline substances to acid soil, and to improve the soil pH by using chemical-biological combined repair, so as to improve the acid soil.

[0004] To achieve the above purpose, the present application discloses a method for improving coal mine acid soil in northern grassland area, comprising the following steps:

[0005] Step S100, dividing the original soil into two layers of reducing neutral topsoil layer and reducing barrier layer;

[0006] Step S200, excavating the original soil from top to bottom to form an excavation area, mixing alkaline substances with acid production inhibition improver and excavated soil in steps, first applying alkaline substances for one week, and then applying acid production inhibition improver, to form improved reducing neutral topsoil;

[0007] Step S300, laying a reducing barrier layer constructed by reducing substances and clay particles at the bottom of the excavation area, wherein the clay particles are taken from sandy soil between 40-100cm of land disturbed by the mine;

[0008] Step S400, backfilling the improved topsoil to create acid-base conditions suitable for the growth of acid-tolerant plants;

[0009] Step S500, mixing acid-tolerant and cold-tolerant alfalfa and tall fescue to repair the coal mine acid soil, and the weight parts of the seeds sown are: alfalfa 1-3 parts, and tall fescue 5-10 parts.

[0010] Further, the original soil is excavated to a depth of 30-40 cm, and the thickness of the reduction barrier layer is 5-10 cm.

[0011] Further, the alkaline substance includes one or more of limestone, dolomite, montmorillonite, desulfurized gypsum, fly ash, etc., and the addition amount of the alkaline substance is determined according to the pH of the soil, when pH < 3, 500 g / m2 is added; when 3 < pH < 4, 200-350 g / m2 is added; when 4 < pH < 5, 1000 g / m2 is added; when pH > 5, no alkaline substance is added, so that pH > plant growth level, at this time, it is the minimum pH value of the plant growth limit.

[0012] Further, the reduction improvement agent includes organic reducing substance, coal-based reducing substance, metal ion chelate and soil biological modifier; wherein the organic reducing substance is 30-50 parts by weight, the coal-based reducing substance is 30-50 parts by weight, the metal ion chelate is 1-2 parts by weight, and the soil biological modifier is 1-3 parts by weight.

[0013] Further, the metal ion chelate includes one or more of organic acid, ethylenediaminetetraacetic acid disodium salt and potassium tartrate.

[0014] Further, the soil biological modifier is a multifunctional agent, and the multifunctional agent is one or more of bacillus subtilis, bacillus licheniformis, EM fungicide, yeast, actinomycetes and nitrogen-fixing bacteria.

[0015] Further, in step 300, the reducing substance includes organic reducing substance and coal-based reducing substance, wherein the organic reducing substance is one or more of cow and sheep manure, household garbage compost, straw compost and wood ash, and the coal-based reducing substance is peat.

[0016] Further, in the reducing substance, the organic reducing substance and the coal-based reducing substance are 1:1 by weight.

[0017] Further, in step 300, the weight of the reducing substance is determined according to the different soil oxidation-reduction potentials, when soil Eh > 500 mV, the reducing substance is added and measured until Eh ≤ 500 mV and soil organic matter content > 4%; when the original soil Eh ≤ 500 mV, the soil organic matter content > 4% according to the soil fertility.

[0018] The beneficial effects of the present application are:

[0019] (1) By the physical-chemical-plant combined management mode, the reducing environment of the soil is shaped, and the acid soil in the north coal mine is repaired;

[0020] (2) the soil is divided into a reductive neutral topsoil layer and a reductive barrier layer, in the upper layer, the alkaline substance and the acid production inhibiting modifier are mixed with the excavated topsoil in steps to realize the double acid control of relieving acidity and continuously inhibiting acid; the reductive barrier layer made of reductive substance and clay particles is laid at the bottom to avoid the capillary action of acidic water in the lower layer from returning upward;

[0021] (3) the alkaline substance is used to adjust the pH of the soil first, then the reductive substance is used to inhibit the oxidation acid production of the sulfur-containing mineral, and the metal chelate is used to convert Al3+ and Fe3+ in the soil into low-toxic or non-toxic chelated forms to relieve the toxic effect of excessive metal on plants;

[0022] (4) the soil biological modifier is applied to improve the community structure of soil microorganisms, accelerate the energy flow and material circulation, and provide a growing site condition for plants;

[0023] (5) alfalfa and tall fescue are mixed and sowed, and are rolled back into the field in the harvest season to further optimize the soil environment. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a schematic view of dividing the original soil into a topsoil layer and a reductive isolation layer; DETAILED DESCRIPTION

[0025] The application will be further described in detail below in combination with the drawings and specific embodiments.

[0026] The application discloses a method for improving acid soil in a northern grassland coal mine, and is used for improving acid soil caused by oxidation acid production of sulfur-containing minerals in a northern open-pit coal mine pit and a dump.

[0027] Firstly, the soil to be improved is divided into a reductive neutral topsoil layer and a reductive barrier layer, as shown in Figure 1 the soil is excavated to a depth of 30 cm, wherein the reductive barrier layer is 10 cm, and the topsoil layer is 20 cm. The soil to be improved is excavated from top to bottom to form an excavation area, the alkaline substance and the acid production inhibiting modifier are mixed with the excavated soil to form the improved topsoil. The reductive barrier layer made of reductive substance and clay particles is laid at the bottom of the excavation area; the improved topsoil is backfilled to generate acid-base conditions suitable for the growth of acid-resistant plants; alfalfa and tall fescue are mixed and sowed to repair the acid soil in the coal mine.

[0028] The step of mixing the distribution with the excavated soil is to first apply the alkaline substance for one week and then apply the acid-inhibiting substance. In specific use, the soil acidity of the soil to be improved is first determined, the amount of the alkaline substance is determined according to the soil acidity, and then the alkaline substance and the acid-inhibiting improvement agent are put into the soil to be improved and mixed uniformly with the soil. The alkaline substance includes one or more of limestone, dolomite, montmorillonite, desulfurized gypsum, and fly ash, and the amount of the alkaline substance is determined according to the soil pH. When the pH is less than 3, 500 g / m2 of the alkaline substance is added; when the pH is between 3 and 4, 200-350 g / m2 of the alkaline substance is added; when the pH is between 4 and 5, 100 g / m2 of the alkaline substance is added; and when the pH is greater than 5, no alkaline substance is added, so that the pH is greater than the plant growth level. At this time, it is the minimum pH value of the plant growth limit.

[0029] The acid-inhibiting improvement agent includes organic reducing substances, coal-based reducing substances, metal ion chelates, and soil biological improvement agents. Among them, the organic reducing substances and the coal-based reducing substances belong to reducing substances, which are used in the construction of the neutral topsoil layer and the reduction barrier layer. The metal ion chelates and the soil biological improvement agents belong to acid-inhibiting improvement agents. Specifically, the organic reducing substances include one or more of various organic matters such as cow and sheep manure, household waste compost, straw compost, and wood ash; and the coal-based reducing substance is coal slime.

[0030] In the construction of the reduction barrier layer, the weight parts of the reducing substance are determined according to the different soil oxidation-reduction potentials. When the soil Eh is greater than 500 mV, the reducing substance is added and measured until the Eh is less than or equal to 500 mV and the soil organic matter content is greater than 4%. When the original soil Eh is less than or equal to 500 mV, the soil fertility is adjusted so that the soil organic matter content is greater than 4%. The acid-inhibiting improvement agent includes the following components in the following weight parts: organic reducing substance 30-50 parts, coal-based reducing substance 30-50 parts, metal ion chelate 1-2 parts, and soil biological improvement agent 1-3 parts. The metal ion chelate includes one or more of organic acid, ethylenediaminetetraacetic acid disodium salt, and potassium tartrate. The clay particles are taken from sandy soil between 40-100 cm of land disturbed by mining.

[0031] The soil biological improvement agent is a multifunctional agent. Specifically, the multifunctional agent is one or more of Bacillus subtilis, Bacillus licheniformis, EM bacterial agent, yeast, actinomycetes, and nitrogen-fixing bacteria, and the effective viable count of the multifunctional bacterial agent is greater than or equal to 100 billion / g.

[0032] The acid-tolerant plants include alfalfa and tall fescue, and the weight parts of the seeds for sowing are as follows: alfalfa 1-3 parts and tall fescue 5-10 parts.

[0033] Example 1

[0034] The soil pH is measured as 4.5, Eh = 650 mV, the soil is excavated 30 cm, and the excavated soil is mixed with lime, cow and sheep manure, coal slime, organic acid and Bacillus subtilis in the proportion of 100 g / m2, 2000 g / m2, 2000 g / m2, 50 g / m2 and 50 g / m2 respectively, and the soil is mixed for one week; the clay particles, cow and sheep manure, household garbage, peat are filled into the soil in the proportion of 100:40:30:50:1:1 by weight, a 10 cm reduction barrier layer is formed, and the improved soil is filled on top. Plant alfalfa and tall fescue in the proportion of 1:3.

[0035] Example 2

[0036] The soil pH is measured as 4.5, Eh = 650 mV, the soil is excavated 30 cm, and the excavated soil is mixed with lime, cow and sheep manure, coal slime, organic acid and Bacillus subtilis in the proportion of 100 g / m2, 2000 g / m2, 2000 g / m2, 50 g / m2 and 50 g / m2 respectively, and the soil is mixed for one week; the clay particles, cow and sheep manure, household garbage, peat are filled into the soil in the proportion of 100:40:30:50:1:1 by weight, a 10 cm reduction barrier layer is formed, and the improved soil is filled on top. Plant alfalfa and tall fescue in the proportion of 1:3.

[0037] Example 3

[0038] The soil pH is measured as 4.5, Eh = 650 mV, the soil is excavated 30 cm, and the excavated soil is mixed with lime, cow and sheep manure, coal slime, organic acid and Bacillus subtilis in the proportion of 100 g / m2, 2000 g / m2, 2000 g / m2, 50 g / m2 and 50 g / m2 respectively, and the soil is mixed for one week; the clay particles, cow and sheep manure, household garbage, peat are filled into the soil in the proportion of 100:40:30:50:1:1 by weight, a 10 cm reduction barrier layer is formed, and the improved soil is filled on top. Plant alfalfa and tall fescue in the proportion of 1:3.

[0039] Comparative Example 1

[0040] The same as Example 1, except that the soil is not improved, and tall fescue and alfalfa are directly planted.

[0041] Comparative Example 2

[0042] The same as Example 1, except that the reduction barrier layer is not set, the soil is improved and filled, and tall fescue and alfalfa are planted.

[0043] Comparative Example 3

[0044] The same as Example 1, except that the soil is not improved, but the reduction barrier layer is set, and tall fescue and alfalfa are planted.

[0045] Comparative Example 4

[0046] Same as Example 2, except that no soil amendment was performed.

[0047] Comparative Example 5

[0048] Same as Example 3, except that no soil amendment was performed.

[0049] The plant growth status after soil improvement using the methods of Examples 1-3 and Comparative Examples 1-5 was statistically analyzed, and the results are shown in Table 1.

[0050] Table 1 Plant growth status

[0051]

[0052]

[0053] Conclusion: The germination rate, ten-day survival rate, two-month survival rate and plant biomass of the experimental group were significantly improved after the improvement, indicating that the improvement scheme can effectively improve the site conditions of plants and promote plant growth.

[0054] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes that can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention are all within the protection scope of the claims of the present invention.

Claims

1. A method of ameliorating acid soils of coal mines in the northern prairie region, characterized by, The method comprises the following steps: Step S100, dividing the original soil into a reduction neutral surface layer and a reduction barrier layer; Step S200, excavating the original soil from top to bottom to form an excavation area, mixing the alkaline substance with the acid production inhibition modifier and the excavated soil in steps, first applying the alkaline substance for one week, then applying the acid production inhibition modifier, to form the improved reduction neutral surface layer soil; The acid production inhibition modifier comprises organic reducing substance, coal-based reducing substance, metal ion chelate and soil biological modifier; wherein the organic reducing substance is 30-50 parts by weight, the coal-based reducing substance is 30-50 parts by weight, the metal ion chelate is 1-2 parts by weight, and the soil biological modifier is 1-3 parts by weight; The metal ion chelate comprises one or more of organic acid, ethylenediaminetetraacetic acid disodium salt and potassium tartrate; The soil biological modifier is a multifunctional agent, and the multifunctional agent is one or more of bacillus subtilis, bacillus licheniformis, EM bacterial agent, yeast, actinomycetes and nitrogen-fixing bacteria; Step S300, laying a reduction barrier layer constructed by reducing substance and clay particles at the bottom of the excavation area, wherein the clay particles are taken from sandy soil between 40-100 cm of the disturbed land in the mining area; Step S400, backfilling the improved surface layer soil to produce acid-alkali conditions suitable for the growth of acid-tolerant plants; Step S500, mixing acid-tolerant and cold-tolerant alfalfa and tall fescue to repair the coal mine acid soil, and the weight parts of the seeds sown are: alfalfa 1-3 parts and tall fescue 5-10 parts.

2. The method for improving acidic soil of coal mine in northern grassland region according to claim 1, characterized in that, The excavation depth of the original soil is 30-40 cm, and the thickness of the reduction barrier layer is 5-10 cm.

3. The method for improving acidic soil of coal mine in northern grassland region according to claim 1, characterized in that, The alkaline substance comprises one or more of limestone, dolomite, montmorillonite, desulfurized gypsum and fly ash, and the addition amount of the alkaline substance is determined according to the pH of the soil, when pH<3, 500 g / m2 is added; when 3<pH<4, 200-350 g / m2 is added; when 4<pH<5, 1000 g / m2 is added; when pH>5, no alkaline substance is added, so that pH>plant growth level, which is the minimum pH value of plant growth limit.

4. The method for improving acidic soil of coal mine in northern grassland region according to claim 1, characterized in that, In step 300, the reducing substance comprises organic reducing substance and coal-based reducing substance, wherein the organic reducing substance is one or more of cow and sheep manure, household garbage compost, straw compost and wood ash; and the coal-based reducing substance is peat.

5. The method for improving acidic soil of coal mine in northern grassland region according to claim 4, characterized in that, In the reducing substance, the weight parts of the organic reducing substance and the coal-based reducing substance are 1:

1.

6. The method for improving acidic soil of coal mine in northern grassland region according to claim 1, characterized in that, In step 300, the weight parts of the reducing substance are determined according to the different soil oxidation-reduction potentials, when soil Eh>500 mV, the reducing substance is added and determined until Eh≤500 mV and soil organic matter content>4%; when the original soil Eh≤500 mV, the soil organic matter content is>4% according to the soil fertility.

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