A saline-alkali soil conditioner, preparation method and saline-alkali soil conditioner

Abstract

The present invention belongs to the technical field of coordinated utilization of multi-industry waste and saline-alkali soil improvement, and discloses a saline-alkali soil improver, a preparation method and a saline-alkali soil improvement method, wherein the saline-alkali soil improver is composed of modified iron tailings, modified fly ash, pig manure organic fertilizer and decomposed peanut shells according to a weight ratio of 8:1:4:1, wherein the pig manure organic fertilizer is mixed and modulated by pig manure and organic matter according to a ratio of 8:2. The improver of the present invention significantly increases the organic matter content of saline-alkali soil, regulates soil acidity and alkalinity, enhances the water retention capacity of the soil, improves the air permeability of the soil, improves the growth condition of plants, and has a good effect on medium and low fertility saline-alkali soil. The improvement method of the present invention has a simple process, is easy to implement, is pollution-free, has a wide range of raw material sources, is cheap, has low production costs, can quickly and effectively supplement the organic matter content, effectively increases the organic matter content in saline-alkali soil, and provides a suitable environment for plant growth.

Description

Technical Field

[0001] The present invention belongs to the technical field of coordinated utilization of multi-industry wastes and saline-alkali soil improvement, and in particular relates to a saline-alkali soil improver, a preparation method and a saline-alkali soil improvement method. Background Art

[0002] With the continuous development of economy and society, soil degradation in my country has become increasingly prominent. Problems such as salinization, nutrient deficiency, and structural degradation have seriously affected crop production and the sustainable development of agriculture. The total area of ​​saline soil in my country is about 3.69×10 7 hm 2 , of which agricultural land salinization is about 7.6×10 6 hm 2 , accounting for about 1 / 5 of my country's agricultural arable land area. How to maintain soil quality, improve saline-alkali soil, eliminate soil toxicity, and reduce the spread of soil-borne diseases has become the focus of attention. The correct use of soil improvement products can effectively alleviate many of the above problems, so the use and research of soil improvement products are gradually favored.

[0003] With the rapid development of world economic integration, the solid waste generated in daily life and production and operation activities has increased dramatically. Not only does it occupy a large amount of land resources due to its stacking, but also because of its diverse and complex components and the potential and long-term harm of its hazards, it is easy to cause direct, indirect or potential pollution to the environment, and even trigger secondary geological disasters such as collapse, landslide, mudslide and debris flow.

[0004] The chemical composition of iron tailings mainly includes SiO2, Al2O3, Fe2O3, CaO, MgO, etc. Among them, SiO2, CaO, MgO, etc. are the medium elements required by plants, and they also contain some other trace elements. If it is modified and activated, it can be called a potential raw material for soil conditioner. Fly ash is the main solid waste discharged by coal-fired power plants. With the development of the power industry, the amount of fly ash discharged from coal-fired power plants has increased year by year, becoming one of the largest industrial waste residues discharged in my country. Therefore, the reuse of fly ash and turning waste into treasure has become an important technical and economic policy in economic construction, and an important means to solve the contradiction between environmental pollution in power production and resource shortage.

[0005] In the existing patent CN112322305A, iron ore tailings, activated carbon, coal slag, limestone, and sodium carboxymethyl cellulose are selected as raw materials, and the raw materials are simply compounded, and agricultural waste is not fully utilized. CN108795440A uses biochar, rice husks, ceramsite, organic fertilizer, and attapulgite powder as raw materials for improvers, uses straw to burn biochar at high temperature, and uses animal feces to ferment and make organic fertilizer to achieve the utilization of agricultural waste. CN110317097A uses solid wastes such as blast furnace slag to mix with polymer water retaining agents, borax, zinc sulfate and trace bactericides, and performs high-temperature calcination treatment on the solid waste. CN114887584A uses fly ash as a soil improver, and modifies it with water, ethanol, silane coupling agent, amino acid aqueous solution and hydrochloric acid. At present, soil improvers have been widely used in the improvement of degraded soils, but most of them have a single improvement function and high improvement cost, and fail to achieve the synergistic improvement of multiple soil indicators.

[0006] Through the above analysis, the problems and defects of the existing technology are: the existing soil conditioners have a single improvement function, the raw materials are not fully utilized, the improvement cost is high, and the coordinated improvement of multiple soil indicators cannot be achieved. Summary of the invention

[0007] In order to overcome the problems existing in the related art, the embodiments disclosed in the present invention provide a saline-alkali soil conditioner, a preparation method and a saline-alkali soil improvement method, and the technical scheme is as follows:

[0008] The invention is realized in this way: a saline-alkali soil conditioner is composed of modified iron tailings, modified fly ash, pig manure organic fertilizer and decomposed peanut shells in a weight ratio of 8:1:4:1.

[0009] The raw material pretreatment includes: air drying, sieving and drying the iron tailings, and then washing, drying, grinding and sieving the fly ash;

[0010] The raw material modification includes: placing the iron tailings in a muffle furnace for calcination to obtain activated iron tailings; then modifying the fly ash with a sulfuric acid solution to obtain modified fly ash;

[0011] The preparation of the saline-alkali soil conditioner comprises: mixing the modified iron tailings and fly ash with pig manure organic fertilizer and decomposed peanut shells to obtain the saline-alkali soil conditioner.

[0012] Furthermore, the pig manure organic fertilizer is prepared by mixing pig manure and organic matter in a weight ratio of 8:2.

[0013] Another object of the present invention is to provide a method for preparing a saline-alkali soil conditioner, the method being used to prepare the saline-alkali soil conditioner, the method comprising:

[0014] S1, raw material pretreatment: after the iron tailings are air-dried, screened and dried, the fly ash is pre-treated by washing, drying, grinding and screening;

[0015] S2, raw material modification: placing the iron tailings in a muffle furnace for calcination to obtain activated iron tailings; then modifying the fly ash with a sulfuric acid solution to obtain modified fly ash;

[0016] S3, mixing the modified iron tailings and fly ash with pig manure organic fertilizer and decomposed peanut shells to obtain a saline-alkali soil conditioner.

[0017] In step S1, raw materials are pre-processed, including:

[0018] The iron tailings are sequentially air-dried, passed through an 18-mesh screen and dried;

[0019] The fly ash recovered from the power plant is processed through an 18-mesh screen, and the processed fly ash is rinsed with deionized water, dried and ground, and then processed through a 100-mesh screen and sealed for use.

[0020] In step S2, the raw materials are modified, including:

[0021] The iron tailings in step S1 are placed in a muffle furnace for calcination and cooled to obtain activated iron tailings;

[0022] The fly ash in step S1 is modified with a 1.73 mol / L sulfuric acid solution at a heating temperature of 79.51° C. for a heating time of 1.87 h. The fly ash after acid leaching is filtered, washed, dried and ground to finally obtain modified fly ash.

[0023] Furthermore, during the modification process of the iron tailings, the calcination temperature was 800°C and the calcination time was 1.5 h.

[0024] Furthermore, during the fly ash modification process, the solid-liquid ratio of fly ash and sulfuric acid solution was 1:5.

[0025] In combination with all the above technical solutions, the beneficial effects of the present invention are as follows: in order to take into account the resource utilization of industrial and agricultural wastes, the present invention uses iron tailings rich in trace elements, fly ash with a loose porous structure, and industrial and agricultural wastes such as straw and feces rich in organic matter as raw materials, and modifies and optimizes them through physical and chemical means such as high-temperature calcination and acid treatment. The goal is to synergistically improve functions such as soil structure optimization, salinization reduction, and soil fertilization. The modification technologies and compounding schemes of different industrial and agricultural wastes are analyzed, and the goal is to synergistically improve soil physical and chemical and fertility indicators such as porosity, bulk density, organic matter, alkaline nitrogen, and available phosphorus. A multifunctional green soil conditioner is prepared, which has the advantages of low production cost and good improvement effect, and can be applied to the field of soil improvement.

[0026] The improver of the present invention significantly increases the organic matter content of saline-alkali soil, regulates soil pH, enhances soil water retention capacity, improves soil air permeability, improves plant growth conditions, and has a good effect on medium- and low-fertility saline-alkali soil.

[0027] The raw materials of the improver of the present invention are all industrial and agricultural wastes, which realizes the comprehensive utilization of "reduction, resource utilization and harmlessness" of solid wastes. It is a practical technology that conforms to the concept of circular economy and has practical application value.

[0028] The improvement method of the present invention has simple process, is easy to implement, is pollution-free, has a wide source of raw materials, is inexpensive, has low production cost, can quickly and effectively supplement the organic matter content, effectively increases the organic matter content in saline-alkali soil, provides a suitable environment for plant growth, has a wide range of applications, is highly operable, is easy to promote and apply to other types of soils, and has great promotion and application value.

[0029] After the implementation of soil conditioner technology, the expected benefits include improving soil quality, increasing agricultural product output, and improving soil structure and ecological environment, indirectly improving the quality of life of residents and bringing economic benefits, while increasing biodiversity and reducing soil erosion. From a commercial perspective, the use of industrial waste as saline-alkali soil conditioner can not only effectively solve the problem of waste disposal, but also promote environmental protection and promote the growth of the organic fertilizer industry and related industrial chains. Most of the current studies on conditioners directly apply raw materials. Although some studies involve modification, they are limited to describing changes in composition. This study modified the waste to explore the effects of different calcination conditions on the activity of elements in tailings and the changes in the specific surface area of ​​fly ash under sulfuric acid modification. By modifying the raw materials, it is adapted to the needs of soil pond improvement. This technical solution improves the improvement effect of the conditioner on saline-alkali soil by modifying raw materials and optimizing formulas and processes.

[0030] Traditional saline-alkali soil conditioners often rely on the purchase of expensive raw materials, while this conditioner utilizes industrial and agricultural waste to reduce costs; improper treatment of industrial and agricultural waste will cause environmental pollution, while this technical solution realizes the resource utilization of waste and reduces the environmental burden; traditional conditioners have limited improvement effects on saline-alkali soil, while this conditioner improves the improvement effect by optimizing the formula and process; traditional conditioners may introduce alien species or harmful chemicals, while this conditioner is based on natural waste to reduce ecological risks; the production process of traditional conditioners may be relatively complicated, while this new conditioner simplifies the production process and facilitates promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings herein are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the description, serve to explain the principles of the present disclosure;

[0032] Figure 1 It is a flow chart of a method for preparing a saline-alkali soil conditioner by collaboratively preparing wastes from multiple industries provided in an embodiment of the present invention;

[0033] Figure 2 is a principal component analysis score diagram of an orthogonal test of wasteland soil provided by an embodiment of the present invention;

[0034] Figure 3 It is a principal component analysis score diagram of a potted plant experiment provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0036] The innovation of the present invention lies in that the raw materials are modified and the proportions are adjusted to make them suitable for soil improvement. The present invention modifies the waste and explores the influence of different calcination conditions on the activity of elements in tailings and the change of the specific surface area of ​​fly ash under sulfuric acid modification conditions, aiming to develop materials suitable for soil improvement, thereby providing a theoretical basis for the reuse of industrial solid waste.

[0037] This method uses iron tailings as the main raw material, combined with fly ash, organic fertilizer and peanut shells to prepare a new type of soil conditioner, the weight ratio of which is: modified iron tailings: modified fly ash: pig manure organic fertilizer: decomposed peanut shells = 8:1:4:1. The pig manure organic fertilizer includes pig manure and organic matter mixed in a ratio of 8:2 (different in different seasons, mostly wheat straw in summer, mostly corn straw and peanut straw in autumn and winter). The effect was verified by potted plant experiments and the optimal application amount was determined to be 5%. The results show that the conditioner can effectively increase the organic matter content of saline-alkali soil, adjust the pH value, enhance water retention and air permeability, and significantly improve plant growth. It is especially suitable for the improvement of medium and low fertility saline-alkali soil.

[0038] The research and development test of the ratio of the improver components is detailed in Example 1.

[0039] like Figure 1 As shown, the method for preparing a soil conditioner from iron tailings provided in an embodiment of the present invention comprises the following steps:

[0040] S1: Raw material pretreatment:

[0041] S1-1: First, the iron tailings are preliminarily air-dried, passed through an 18-mesh screen and dried;

[0042] S1-2: The fly ash recovered from the power plant is processed through an 18-mesh screen. The processed fly ash is rinsed with deionized water, dried and ground, and then processed through a 100-mesh screen and sealed for use.

[0043] S2: Raw material modification: The iron tailings and fly ash modification experiments are detailed in Example 2.

[0044] S2-1: taking the iron tailings in step S1 and calcining them in a muffle furnace at a temperature of 800 degrees Celsius for 1.5 hours, and cooling them to obtain activated iron tailings;

[0045] S2-2: The fly ash in step S1 is modified using a 1.73 mol / L sulfuric acid solution, wherein the solid-liquid ratio is 1:5, the heating temperature is 79.51 degrees Celsius, and the heating time is 1.87 hours. The fly ash after acid leaching is filtered, washed, dried, and ground to finally obtain modified fly ash.

[0046] S3: Mixing the iron tailings and fly ash modified in step S2 with commercially available organic fertilizer and peanut shells.

[0047] The planting soil of the present invention is taken from the saline-alkali soil in the estuary area of ​​Dongying.

[0048] The method for improving iron tailings soil using the above-mentioned iron tailings soil conditioner comprises the following steps:

[0049] The iron tailings conditioner was applied to saline-alkali soil by tillage, and the application amount of the iron tailings soil conditioner was the area of ​​the improved area × 20 cm × soil density × 5%.

[0050] Preferably according to the present invention, the tillage depth is 20 cm for mechanical tillage.

[0051] The iron tailings soil conditioner of the present invention effectively reduces the salinity and alkalinity of the soil, increases the content of soil organic matter and trace elements, and has a good improvement on the physical properties of the soil such as particle size, porosity and bulk density.

[0052] The soil improvement effect is detailed in Example 3, and the plant improvement effect is detailed in Example 4.

[0053] Among them, the modified iron tailings can effectively increase the beneficial metal elements in the soil and reduce the salinity of the soil by replacing sodium ions. The modified fly ash has a small particle size and a rough surface, a large specific surface area, and is more likely to form large soil aggregates with soil particles, improving the physical properties of the soil. The modified fly ash has a low pH and also has the effect of reducing soil alkalinity. In addition to providing organic matter and nitrogen, phosphorus and potassium elements, the combination of pig manure organic fertilizer and fermented peanut shells can also form humic acid, which also has a good improvement effect on saline-alkali soil.

[0054] Example 1: Improver formula development test

[0055] The test selected uncultivated saline-alkali soil from wasteland for analysis through orthogonal test, named as wasteland soil test group, hereinafter referred to as WT (Wildland Treatment). A four-factor five-level orthogonal experimental design was adopted, without considering the first-order interaction, and two groups of repeated controls were set for each treatment to determine the optimal ratio of iron tailings, fly ash, pig manure and peanut shells in soil conditioners. The combination of conditioners is shown in Table 1. A blank test was set as a control for each test group, and the blank was listed as an error.

[0056] Table 1 L16 (45) orthogonal experimental design:

[0057]

[0058] Iron tailings, fly ash, pig manure and peanut shells were mixed evenly according to the requirements of the orthogonal experimental design table to prepare soil conditioners with different proportions. After the two types of soils were collected, they were air-dried and passed through a 2mm sieve. The sieved soil was mixed evenly with the conditioner and watered at 70% of the maximum water holding rate. The flower pots were 15cm in diameter and 12cm in height. There were drainage holes at the bottom. Before filling the soil, a gauze was placed at the bottom, and a gravel layer about 2cm high was laid for drainage and salt removal. When filling the soil, it was laid layer by layer to ensure uniformity. Vaseline was applied to the wall of the flower pot to prevent edge effects with the soil. During this period, the gravimetric method was used for regular watering to maintain a maximum water holding rate of 60-70%. After 30 days of equilibrium, the soil was air-dried, ground and sieved. The soil was collected and its physical and chemical indicators such as organic matter, alkaline nitrogen, available phosphorus, available potassium, available silicon, available iron, calcium ions, magnesium ions, potassium ions, bulk density, porosity, pH value, conductivity, sodium ions and sand particle ratio were determined.

[0059] Origin2022 software was used to perform principal component analysis (PCA) on the test groups and their indicators of the test results. Positive indicators such as porosity, organic matter, alkaline nitrogen, available phosphorus, available potassium, available silicon, effective iron, calcium ions, magnesium ions, potassium ions and sand particle ratio were treated normally, and reverse indicators such as bulk density, pH value, conductivity and sodium ions were treated inversely.

[0060] The scores of the principal component analysis of the orthogonal test for wasteland soil are shown in Table 2 and Figure 2 shown.

[0061] Table 2 Comprehensive score table of wasteland soil treatments:

[0062]

[0063] Through PCA comprehensive score evaluation and ranking, the WT4 test group scored the highest and had the best improvement effect, but excessive addition of fly ash could easily have an impact on the environment. WT10 and WT13 had similar scores, and WT5 scored slightly lower. Considering the recycling value of iron tailings, WT13 was selected as the improver formula for wasteland soil, namely A4, B1, C4, and D2, that is, modified iron tailings: modified fly ash: pig manure organic fertilizer: decomposed peanut shells = 8:1:4:1.

[0064] Example 2: Experiment on optimization of modification conditions of iron ore tailings fly ash

[0065] (1) Optimization of iron tailings calcination time

[0066] Representative iron tailings samples were selected, dried, ground and sieved to ensure that the samples had a uniform particle size distribution. The iron tailings samples were placed in a crucible and placed in a muffle furnace. The iron tailings samples were calcined at five different times: 0.5h, 1.0h, 1.5h, 2.0h and 2.5h. The calcination temperature at each time was fixed at 600℃ to ensure uniform temperature inside the sample. After calcination, each sample was cooled, and the contents of effective silicon, available potassium, effective iron, calcium ions and magnesium ions in the iron tailings at different calcination times were measured to determine the optimal calcination time.

[0067] Table 3 Iron tailings ion content at different calcination times:

[0068]

[0069] As shown in Table 3, the content of effective silicon is higher when the calcination time is between 0.5h and 1.5h. The content of available potassium and effective iron in iron tailings shows an overall trend of gradual decrease with the increase of calcination time, while the content of calcium and magnesium ions shows a trend of gradual increase and stabilization or even decrease with the increase of calcination time. After comprehensive analysis, 1.5h is selected as the calcination time of iron tailings.

[0070] (2) Optimization of iron tailings calcination temperature

[0071] Using the calcination time determined above, prepare the iron tailings samples, ensure that the initial conditions of each sample are the same, put the iron tailings samples into a crucible and place them in a muffle furnace, and calcine the iron tailings samples at six different temperatures of 200°C, 400°C, 600°C, 800°C, 900°C and 1000°C. The calcination time at each temperature is fixed to the optimal preparation temperature determined above. After the calcination is completed, each sample is cooled, and the samples before and after calcination are collected for the content of effective silicon, available potassium, effective iron, calcium ions and magnesium ions, and the optimal calcination temperature is determined by comparison. According to the analysis results, the optimal calcination temperature and time parameters are finally determined, as shown in Table 4.

[0072] Table 4 Iron tailings ion content at different calcination temperatures:

[0073]

[0074] In summary, the iron tailings can effectively activate the contents of effective silicon, effective iron and calcium ions at 800°C, while the contents of available potassium and magnesium ions reach the highest at 600°C. Considering the improvement effect of calcium ions in the SiO2 phase of the iron tailings on saline-alkali soil, 800°C is selected as the optimal calcination temperature for iron tailings modification. At this temperature, the contents of effective silicon, effective iron, calcium ions, magnesium ions and available potassium in the iron tailings all reach a good level, which is conducive to improving the effect of iron tailings as a soil conditioner.

[0075] (3) Preparation test of modified fly ash using response surface model

[0076] The response surface experimental design method was used to select acid modification concentration, reaction temperature and time as influencing factors, and set the corresponding levels. Taking the central composite design as an example, three levels of the three factors can be set, as shown in Table 5.

[0077] Table 5 Fly ash modification test design table:

[0078]

[0079] Typical fly ash was selected as the experimental raw material and screened to ensure uniform particle size distribution. A certain amount of fly ash sample was weighed and added to deionized water to make a suspension. According to the design level in Table 6, sulfuric acid solution of different concentrations was added to the suspension at a liquid-solid ratio of 5:1, and the solution was transferred to a constant temperature water bath. Turn on the magnetic stirrer, adjust to the appropriate speed, and monitor the reaction temperature at the same time. When the reaction time reaches the set value, stop heating immediately, take out the sample and wash it with deionized water to neutrality, and then dry it in an oven to constant weight. The dried sample was ground and sieved, and the specific surface area was determined using a fully automatic specific surface and porosity analyzer. All experimental data were collected and analyzed using Design-Expert software. A quadratic polynomial model was established, and the influence of acid modification concentration, temperature and time on the specific surface area of ​​fly ash was obtained by regression analysis. According to the results of response surface analysis, the optimal combination of acid modification concentration, temperature and time was determined, and the optimal acid modification conditions were determined.

[0080] Table 6 Experimental design and results:

[0081]

[0082] By using the numerical optimization function of DesignExpert10.0 software, in order to obtain the optimal conditions, the specific surface area of ​​fly ash is set to be maximized. At the same time, for cost saving considerations, the importance of other operating parameters is reduced and set to the minimum. The optimal operating conditions can be obtained as the optimization test conditions predicted by the quadratic model: reaction temperature 79.51℃, reaction time 1.87h, sulfuric acid concentration 1.73mol / L. Under these conditions, the modification is carried out in a solution with a solid-liquid ratio of 1:5. After the modification is completed, the slurry is filtered, washed with deionized water, and dried at 105℃ in turn, and finally sulfuric acid-modified fly ash is obtained.

[0083] Example 3: Improvement of soil structure, salinity and fertility properties by soil conditioners

[0084] The soil conditioner was added to the wasteland soil at 5%, and the improvement effect is shown in Table 7.

[0085] Table 7 Improvement effect:

[0086]

[0087] As shown in Table 7, the improver has a significant effect on improving the uncultivated wasteland soil, with an increase of 22.23% in organic matter, and a good improvement effect on the alkaline nitrogen, available phosphorus and available potassium in the soil, with an improvement rate between 29.70% and 82.75%. At the same time, the mineral elements of effective silicon and calcium and magnesium ions in the soil are improved, but because the effective silicon content of the soil itself is high, the improvement is not obvious. In addition, from the improvement effect of bulk density and porosity, it can be seen that the improver has a certain improvement effect on the structural properties of the uncultivated wasteland soil. From the improvement effect of pH value and conductivity, it can be seen that the improver has a significant improvement effect on the saline-alkali properties of the uncultivated wasteland soil.

[0088] Example 4: Effect verification of two improvers and selection of dosage

[0089] In order to verify the effect of the amendment formula and determine the appropriate dosage, a potted planting experiment was conducted with alfalfa as the object, and wasteland soil with poor physical and chemical conditions and more development and utilization value was selected to explore the effects of different dosages on plant survival rate, growth rate, biomass and enzyme activity. Through a comprehensive analysis of the above indicators, the effectiveness of the soil amendment was verified and the optimal dosage was determined.

[0090] The soil was divided into five groups, and soil conditioners were added to the wasteland soil at a weight ratio of 0%, 1%, 2%, 5%, and 10%, respectively. Two groups of repeated controls were set up for each group of experiments, and the flower pots and soil treatments were consistent with the above experiments. After one week of maturation, alfalfa seeds were evenly sown in each treated soil, about 10 seeds were sown in each pot, evenly arranged in the planting pot, and the planting depth was about 1 cm. After sowing, the soil was kept moist and placed in a light incubator, the temperature was controlled at 20-25℃, and the light was sufficient. The data obtained are shown in Table 8.

[0091] Table 8 Experimental data for verification of improver effect:

[0092]

[0093] Origin2022 was used to perform principal component analysis (PCA) on different dosage groups and indicators of the test results. Positive indicators such as final survival rate, maximum height, maximum biomass, CAT and SOD were treated normally, and the negative indicator MDA was reversed.

[0094] The principal component comprehensive analysis scores of the potted plant experiment are shown in Table 9 and Figure 3 shown.

[0095] Table 9 Comprehensive analysis score table:

[0096]

[0097] From the comprehensive analysis score table of the five treatments, it can be seen that the highest score is 7.5% dosage, and the lowest score is 0.0%. Through PCA score chart analysis and comprehensive score evaluation ranking, 7.5% dosage has the highest score and the best improvement effect, followed by 5.0% dosage and 10.0% dosage. If only the soil improvement effect is pursued, the 7.5% dosage is selected; if the cost-effectiveness is required while ensuring the soil improvement effect, the 5.0% dosage is selected.

[0098] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0099] To further demonstrate the positive effects of the above embodiment, the present invention conducted the following experiment based on the above technical solution. To compare the effect difference between the improver and conventional commercial improvers, the commercial improver was added to the wasteland soil, and the difference in improvement effect is shown in Table 10.

[0100] Table 10 Comparison of improvement effects:

[0101]

[0102] As shown in Table 10, traditional commercially available improvers performed well in increasing the nitrogen, phosphorus and potassium content in the soil, but had limited effects in increasing the organic matter content and adjusting the pH value, and failed to improve key indicators such as soil density, porosity, conductivity, effective silicon and calcium and magnesium ions. In general, compared with traditional improvers, this improver has the following advantages: The technical solution of saline-alkali soil improver prepared with industrial and agricultural waste has the following advantages over the traditional addition of fertilizers such as chemical fertilizers: This technical solution utilizes industrial and agricultural waste as raw materials, realizes the resource utilization of waste, and reduces the consumption of natural resources; By using waste as raw materials, this technical solution reduces the production cost of improvers, which is of great significance for large-scale promotion and application; It reduces dependence on traditional chemical fertilizers, thereby reducing environmental pollution, which is in line with the development trend of green environmental protection; This technical solution can improve the physical and chemical properties of the soil, increase soil fertility and crop yields.

[0103] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered within the protection scope of the present invention.

Claims

1. A saline-alkali soil conditioner, characterized in that: The saline-alkali soil conditioner is composed of modified iron tailings, modified fly ash, pig manure organic fertilizer and decomposed peanut shells in a weight ratio of 8:1:4:1; The raw material pretreatment includes: air drying, sieving and drying the iron tailings, and then washing, drying, grinding and sieving the fly ash; The raw material modification includes: placing the iron tailings in a muffle furnace for calcination to obtain activated iron tailings; then modifying the fly ash with a sulfuric acid solution to obtain modified fly ash; The preparation of the saline-alkali soil conditioner comprises: mixing the modified iron tailings and fly ash with pig manure organic fertilizer and decomposed peanut shells to obtain the saline-alkali soil conditioner.

2. The saline-alkali soil conditioner according to claim 1, characterized in that The pig manure organic fertilizer is prepared by mixing pig manure and organic matter in a weight ratio of 8:

2.

3. A method for preparing a saline-alkali soil conditioner, characterized in that: The method is used to prepare the saline-alkali soil conditioner according to any one of claims 1 to 2, and the method comprises: S1, raw material pretreatment: after the iron tailings are air-dried, screened and dried, the fly ash is pre-treated by washing, drying, grinding and screening; S2, raw material modification: placing the iron tailings in a muffle furnace for calcination to obtain activated iron tailings; then modifying the fly ash with a sulfuric acid solution to obtain modified fly ash; S3, mixing the modified iron tailings and fly ash with pig manure organic fertilizer and decomposed peanut shells to obtain a saline-alkali soil conditioner.

4. The method for preparing the saline-alkali soil conditioner according to claim 3, characterized in that: In step S1, raw materials are pre-processed, including: The iron tailings are sequentially air-dried, passed through an 18-mesh screen and dried; The fly ash recovered from the power plant is processed through an 18-mesh screen, and the processed fly ash is rinsed with deionized water, dried and ground, and then processed through a 100-mesh screen and sealed for use.

5. The method for preparing the saline-alkali soil conditioner according to claim 3, characterized in that: In step S2, the raw materials are modified, including: The iron tailings in step S1 are placed in a muffle furnace for calcination and cooled to obtain activated iron tailings; The fly ash in step S1 is modified with a 1.73 mol / L sulfuric acid solution at a heating temperature of 79.51° C. for a heating time of 1.87 h. The fly ash after acid leaching is filtered, washed, dried and ground to finally obtain modified fly ash.

6. The method for preparing the saline-alkali soil conditioner according to claim 5, characterized in that: During the modification process of iron tailings, the calcination temperature was 800°C and the calcination time was 1.5h.

7. The method for preparing the saline-alkali soil conditioner according to claim 6, characterized in that: During the fly ash modification process, the solid-liquid ratio of fly ash and sulfuric acid solution is 1:5.

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