Composite silicon-calcium-magnesium soil conditioner for acid soil and preparation method thereof

Abstract

The invention relates to the technical field of soil remediation, and discloses a composite silicon-calcium-magnesium soil conditioner for acid soil and a preparation method thereof. The invention provides a composite silicon-calcium-magnesium soil conditioner for acid soil. The composite silicon-calcium-magnesium soil conditioner is prepared from the following raw materials in parts by mass: 20-30 parts of activated silicon-calcium-magnesium powder, 40-60 parts of decomposed agricultural organic waste and 5-15 parts of a composite microbial agent. After the composite silicon-calcium-magnesium soil conditioner for the acid soil is used for conditioning for 30 days, the pH value of the soil can reach 6.5, exchangeable aluminum can reach 0.1 cmol / kg, available phosphorus can reach 21.7 mg / kg, exchangeable calcium can reach 7.8 cmol / kg, organic matter can reach 25.2 g / kg, and the physical and chemical properties of the acid soil can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of soil remediation technology, and more specifically, to a composite silicon-calcium-magnesium soil conditioner for acidic soils and its preparation method. Background Technology

[0002] Soil acidification is one of the major soil degradation problems facing global agricultural production. Its causes involve multiple factors, including natural soil formation processes, long-term excessive application of chemical nitrogen fertilizers, acid rain deposition, and continuous cropping obstacles. Excessive hydrogen ion concentration in acidic soils leads to the release of large amounts of exchangeable aluminum, iron, manganese, and other toxic metal ions. These ions not only directly inhibit plant root growth and damage cell structure but also hinder the absorption and utilization of essential nutrients such as phosphorus, calcium, and magnesium, resulting in slow crop growth, reduced stress resistance, sharp yield reductions, and even crop failure.

[0003] Currently, the main technology for improving acidic soils relies on the application of traditional mineral conditioners such as quicklime and dolomite powder. While these mineral conditioners can quickly neutralize soil acidity, they may have adverse effects on soil structure and microbial communities.

[0004] Therefore, developing a soil conditioner that can steadily increase soil pH, comprehensively improve soil nutrient structure, and effectively enhance soil fertility has become an urgent need in the field of agricultural soil remediation. Summary of the Invention

[0005] The purpose of this invention is to provide a soil conditioner that can steadily increase soil pH, comprehensively improve soil nutrient structure, and effectively enhance soil fertility.

[0006] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention: A composite silicon-calcium-magnesium soil conditioner for acidic soils, comprising the following raw materials in parts by weight: 20-30 parts activated silicon-calcium-magnesium powder, 40-60 parts decomposed agricultural organic waste, and 5-15 parts compound microbial agent.

[0007] Furthermore, the preparation method of the activated silicon-calcium-magnesium powder includes the following steps: 1) Mix quartz sand, calcite powder and magnesite powder to obtain a premix; 2) Place the silane coupling agent, humic acid, and nano-ferric oxide in water and mix to obtain an activated suspension; 3) Place the premix obtained in step 1) into the activated suspension obtained in step 2) and mix to obtain the activator mixed premix; 4) The activator mixture premix obtained in step 3) is activated by crushing and sieving to obtain the activated material; 5) Dissolve sodium alginate, polyvinyl alcohol, and citric acid in water to obtain an embedding solution; 6) Using fluidized bed spray coating technology, the activated material obtained in step 4) is embedded in the embedding liquid obtained in step 5), and dried to obtain the activated silicon-calcium-magnesium powder.

[0008] Furthermore, in step 1), the mass ratio of the quartz sand, calcite powder and magnesite powder is (1-3):(4-6):(2-4).

[0009] Furthermore, in step 2), the mass ratio of the silane coupling agent, humic acid, nano-ferric oxide and water is (2-4):(4-6):(0.5-1.5):(8-12).

[0010] Furthermore, in step 2), the mixing specifically involves controlling the stirring speed to 100-200 rpm and mixing at room temperature for 3-5 minutes.

[0011] Furthermore, in step 3), the mass ratio of the premix to the activated suspension is (4-6):1.

[0012] Furthermore, in step 3), the mixing specifically involves controlling the stirring speed to 200-300 rpm and mixing at room temperature for 25-35 minutes.

[0013] Furthermore, in step 4), the activation treatment specifically involves: in an air atmosphere, controlling the heating rate at 5°C / min, heating to 350–450°C, holding at that temperature for 30–60 min, and then controlling the heating rate at 10°C / min, heating to 550–650°C, and holding at that temperature for 1.5–2.5 h.

[0014] Furthermore, in step 5), the mass ratio of sodium alginate, polyvinyl alcohol, citric acid and water is (0.5-1.5):(1-2):(0.1-0.5):(80-90).

[0015] Furthermore, in step 5), the dissolution specifically involves: controlling the stirring speed to 200-300 rpm, first heating the water to 80-85°C, then adding polyvinyl alcohol to the water, and after the polyvinyl alcohol is completely dissolved, cooling the temperature to 40-50°C, adding sodium alginate and citric acid, and dissolving completely.

[0016] Furthermore, in step 6), the mass ratio of the activation treatment material to the embedding solution is 1: (0.4 to 0.6).

[0017] Furthermore, in step 6), the parameters of the fluidized bed spray coating technology are: inlet air temperature 50-60℃, spray rate 5-15mL / min, and atomization pressure 0.2-0.4MPa.

[0018] Furthermore, the method for preparing the composted agricultural organic waste includes the following steps: 1) Mix rice straw, sugarcane residue and silkworm excrement, crush and sieve to obtain agricultural organic waste powder; 2) Mix Trichoderma reesei and Proteobacterium chrysosporium to obtain a composting agent; 3) Mix agricultural organic waste powder with composting microbial agent and compost to obtain the composted agricultural organic waste.

[0019] Furthermore, in step 1), the mass ratio of rice straw, sugarcane residue, and silkworm excrement is 1:1:1.

[0020] Furthermore, in step 2), the mass ratio of Trichoderma reesei to Protozoa chrysophagus is 1:1.

[0021] Furthermore, in step 3), the mass ratio of the agricultural organic waste powder to the composting agent is (48-51):1.

[0022] Furthermore, in step 3), the fermentation specifically involves controlling the moisture content to be 40%–60% and fermenting at 40°C for 7–14 days.

[0023] Furthermore, the compound microbial agent is composed of *Azotobacter chrysogenum*, *Bacillus circulans*, and *Nocardia brasiliensis* in a mass ratio of (4–6): (1–3): (0.5–1.5).

[0024] The second technical solution of the present invention: The preparation method of the above-mentioned composite silicon-calcium-magnesium soil conditioner for acidic soil includes the following steps: 1) Mix well-rotted agricultural organic waste and compound microbial inoculant to obtain a premix; 2) Mix the premix obtained in step 1) with the activated silicon-calcium-magnesium powder to obtain the composite silicon-calcium-magnesium soil conditioner.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a composite silicon-calcium-magnesium soil conditioner for acidic soils. After 30 days of conditioning, the soil pH can reach 6.5, exchangeable aluminum can reach 0.1 cmol / kg, available phosphorus can reach 21.7 mg / kg, exchangeable calcium can reach 7.8 cmol / kg, and organic matter can reach 25.2 g / kg, which can effectively improve the physical and chemical properties of acidic soils.

[0026] This invention uses quartz sand, calcite, and magnesite as mineral raw materials. Through synergistic pretreatment with silane coupling agent, humic acid, and nano-ferric oxide, combined with two-stage gradient calcination, it can provide essential nutrients such as silicon, calcium, and magnesium for plant growth. Furthermore, the synergistic pretreatment combined with two-stage gradient calcination causes lattice distortion within the quartz sand, calcite, and magnesite, directionally generating alkaline composite phases such as active calcium silicate and magnesium hydroxide. This significantly improves soil pH regulation efficiency, rapidly neutralizes hydrogen ions and exchangeable aluminum in acidic soils, and promotes further mineral weathering, thereby increasing the solubility of silicon, calcium, and magnesium. This invention employs a sodium alginate-polyvinyl alcohol-citric acid composite encapsulation system to coat activated minerals. On one hand, the encapsulation layer forms a physical barrier, preventing the mineral particles from dissolving rapidly in the initial application stage, thus avoiding drastic fluctuations in local soil pH and protecting the activity of the composite microbial agent. This solves the technical problem of poor compatibility between traditional mineral conditioners and microbial agents. On the other hand, citric acid, as a slow-release regulator, is slowly released under the influence of soil microbial metabolism and changes in environmental humidity, triggering the gradual disintegration of the encapsulation layer. This achieves controlled slow release of nutrients such as silicon, calcium, and magnesium, avoiding nutrient loss and the risk of secondary soil acidification.

[0027] This invention selects Trichoderma reesei and Protozoa chrysospora as a compound composting agent, which can efficiently degrade cellulose and lignin in rice straw, sugarcane bagasse and silkworm excrement, and directionally convert them into stable humus, small molecule organic acids and other growth-promoting substances. The resulting compost has a loose structure and few pathogens and weed seeds, making it not only an excellent soil structure improver, but also a continuous source of organic nutrients.

[0028] This invention constructs a synergistic microbial system by combining *Azotobacter chrysogenum*, *Bacillus circulans*, and *Nocardia brasiliensis*. *Azotobacter chrysogenum* efficiently fixes free nitrogen from the air, converting it into ammonium nitrogen that plants can absorb. *Bacillus circulans* secretes organic acids, effectively activating insoluble phosphorus and potassium in the soil, increasing the available phosphorus content to 25.7 mg / kg and the exchangeable calcium content to 10.8 cmol / kg. *Nocardia brasiliensis* synergistically regulates the soil microecological balance and inhibits the reproduction of harmful pathogens. The synergistic effect of these three components steadily increases the soil pH to the suitable range of 6.1–6.5 while comprehensively improving the soil nutrient structure and effectively enhancing soil fertility. Detailed Implementation

[0029] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0030] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0031] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0032] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This specification and embodiments are merely exemplary.

[0033] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0034] Unless otherwise specified, all raw materials used in the following examples and comparative examples were commercially available. Please refer to Table 1 for details. Table 1 Raw Materials and Specifications

[0035] The following embodiments illustrate a method for preparing a composite silicon-calcium-magnesium soil conditioner for acidic soils, comprising the following steps: 1. Preparation of activated silicon-calcium-magnesium powder 1) The quartz sand, calcite powder and magnesite powder are mixed in a mass ratio of (1-3):(4-6):(2-4) to obtain a premix; 2) According to the mass ratio of silane coupling agent, humic acid, nano-Fe3O4 and water, the silane coupling agent, humic acid and nano-Fe3O4 are placed in water, the stirring speed is controlled at 100-200 rpm, and the mixture is mixed at room temperature for 3-5 min to obtain an activated suspension; 3) According to the mass ratio of premix to activated suspension of (4-6):1, place the premix obtained in step 1) into the activated suspension obtained in step 2), control the stirring speed to 200-300 rpm, and mix at room temperature for 25-35 min to obtain the activator mixed premix; 4) The activator mixture premix obtained in step 3) is activated, crushed, and passed through a 100-mesh sieve to obtain the activated material; The activation treatment specifically involves: in an air atmosphere, controlling the heating rate at 5℃ / min, heating to 350-450℃, holding at that temperature for 30-60 minutes, and then controlling the heating rate at 10℃ / min, heating to 550-650℃, and holding at that temperature for 1.5-2.5 hours. 5) According to the mass ratio of sodium alginate, polyvinyl alcohol, citric acid and water, it is (0.5~1.5):(1~2):(0.1~0.5):(80~90), and the stirring speed is controlled at 200~300 rpm. First, heat the water to 80~85℃, and add polyvinyl alcohol to the water. After the polyvinyl alcohol is completely dissolved, cool it to 40~50℃, add sodium alginate and citric acid, and dissolve them completely to obtain the embedding solution. 6) Using fluidized bed spray coating technology, the activated material obtained in step 4) is embedded in the embedding liquid obtained in step 5) at a mass ratio of 1:(0.4~0.6) of the activated material and the embedding liquid, and dried until the water content is less than 10% to obtain the activated silicon-calcium-magnesium powder. The parameters for fluidized bed spray coating technology are: inlet air temperature 50-60℃, spray rate 5-15mL / min, and atomization pressure 0.2-0.4MPa. 2. Preparation of composted agricultural organic waste 1) Mix rice straw, sugarcane residue and silkworm excrement in a mass ratio of 1:1:1, crush them, and pass them through a 20-mesh sieve to obtain agricultural organic waste powder. 2) Mix Trichoderma reesei and Proteobacterium chrysosporium at a mass ratio of 1:1 to obtain a composting agent; 3) Mix the agricultural organic waste powder and the composting agent at a mass ratio of (48-51):1, control the moisture content to 40%-60%, and compost at 40℃ for 7-14 days to obtain the composted agricultural organic waste. 3. Preparation of compound microbial agents The composite microbial agent was obtained by mixing Azotobacter chrysogenum, Bacillus circulans, and Nocardia brasiliensis in a mass ratio of (4-6):(1-3):(0.5-1.5). 4. Preparation of composite silicon-calcium-magnesium soil conditioner 1) Weigh each raw material according to the following mass proportions: 20-30 parts activated silicon-calcium-magnesium powder, 40-60 parts decomposed agricultural organic waste, and 5-15 parts compound microbial agent; 2) Mix the decomposed agricultural organic waste weighed in step 1) with the compound microbial agent to obtain a premix; 3) Mix the premix obtained in step 2) with the activated silicon-calcium-magnesium powder weighed in step 1) to obtain the composite silicon-calcium-magnesium soil conditioner.

[0036] Example 1 A composite silicon-calcium-magnesium soil conditioner 1. Preparation of activated silicon-calcium-magnesium powder 1) Mix the quartz sand, calcite powder and magnesite powder in a mass ratio of 2:5:3 to obtain a premix; 2) According to the mass ratio of silane coupling agent, humic acid, nano iron oxide and water of 3:5:1:10, silane coupling agent, humic acid and nano iron oxide are placed in water, the stirring speed is controlled at 150 rpm, and the mixture is mixed at room temperature for 4 min to obtain an activated suspension. 3) According to the mass ratio of premix to activation suspension of 5:1, place the premix obtained in step 1) into the activation suspension obtained in step 2), control the stirring speed to 250 rpm, and mix at room temperature for 30 min to obtain the activator mixed premix. 4) The activator mixture premix obtained in step 3) is activated, crushed, and passed through a 100-mesh sieve to obtain the activated material; The activation treatment specifically involves: in an air atmosphere, controlling the heating rate at 5℃ / min, heating to 400℃, holding and calcining for 40 min, and then controlling the heating rate at 10℃ / min, heating to 600℃, and holding and calcining for 2 h. 5) According to the mass ratio of sodium alginate, polyvinyl alcohol, citric acid and water of 1:1.5:0.2:85, control the stirring speed at 250 rpm, first heat the water to 83°C, then add polyvinyl alcohol to the water. After the polyvinyl alcohol is completely dissolved, cool down to 45°C, add sodium alginate and citric acid, and dissolve completely to obtain the embedding solution. 6) Using fluidized bed spray coating technology, the activated material obtained in step 4) is embedded in the embedding liquid obtained in step 5) at a mass ratio of 1:0.5 between the activated material and the embedding liquid, and dried until the water content is less than 10% to obtain the activated silicon-calcium-magnesium powder. The parameters for the fluidized bed spray coating technology are: inlet air temperature 55℃, spray rate 10mL / min, and atomization pressure 0.3MPa. 2. Preparation of composted agricultural organic waste 1) Mix rice straw, sugarcane residue and silkworm excrement in a mass ratio of 1:1:1, crush them, and pass them through a 20-mesh sieve to obtain agricultural organic waste powder. 2) Mix Trichoderma reesei and Proteobacterium chrysosporium at a mass ratio of 1:1 to obtain a composting agent; 3) Mix the agricultural organic waste powder and the composting agent at a mass ratio of 50:1, control the moisture content to 50%, and compost at 40℃ for 10 days to obtain the composted agricultural organic waste. 3. Preparation of compound microbial agents The composite microbial agent was obtained by mixing Azotobacter chrysogenum, Bacillus circulatoryus, and Nocardia brasiliensis in a mass ratio of 5:2:1. 4. Preparation of composite silicon-calcium-magnesium soil conditioner 1) Weigh each raw material according to the following mass proportions: 25 parts activated silicon-calcium-magnesium powder, 50 parts decomposed agricultural organic waste, and 10 parts compound microbial inoculant; 2) Mix the decomposed agricultural organic waste weighed in step 1) with the compound microbial agent to obtain a premix; 3) Mix the premix obtained in step 2) with the activated silicon-calcium-magnesium powder weighed in step 1) to obtain the composite silicon-calcium-magnesium soil conditioner.

[0037] Example 2 A composite silicon-calcium-magnesium soil conditioner 1. Preparation of activated silicon-calcium-magnesium powder 1) Mix the quartz sand, calcite powder and magnesite powder in a mass ratio of 1:4:2 to obtain a premix; 2) According to the mass ratio of silane coupling agent, humic acid, nano iron oxide and water of 2:4:0.5:8, silane coupling agent, humic acid and nano iron oxide are placed in water, the stirring speed is controlled at 100 rpm, and the mixture is mixed at room temperature for 3 min to obtain an activated suspension. 3) According to the mass ratio of premix to activation suspension of 4:1, place the premix obtained in step 1) into the activation suspension obtained in step 2), control the stirring speed to 200 rpm, and mix at room temperature for 25 min to obtain the activator mixed premix. 4) The activator mixture premix obtained in step 3) is activated, crushed, and passed through a 100-mesh sieve to obtain the activated material; The activation treatment specifically involves: heating to 350°C in an air atmosphere at a controlled heating rate of 5°C / min, holding the temperature for 30 min, and then heating to 550°C at a controlled heating rate of 10°C / min, holding the temperature for 1.5 h. 5) According to the mass ratio of sodium alginate, polyvinyl alcohol, citric acid and water of 0.5∶1∶0.1∶80, control the stirring speed at 200 rpm, first heat the water to 80℃, then add polyvinyl alcohol to the water. After the polyvinyl alcohol is completely dissolved, cool down to 40℃, add sodium alginate and citric acid, and dissolve completely to obtain the embedding solution. 6) Using fluidized bed spray coating technology, the activated material obtained in step 4) is embedded in the embedding liquid obtained in step 5) at a mass ratio of 1:0.4 between the activated material and the embedding liquid, and dried until the water content is less than 10% to obtain the activated silicon-calcium-magnesium powder. The parameters for the fluidized bed spray coating technology are: inlet air temperature 50℃, spray rate 5mL / min, and atomization pressure 0.2MPa. 2. Preparation of composted agricultural organic waste 1) Mix rice straw, sugarcane residue and silkworm excrement in a mass ratio of 1:1:1, crush them, and pass them through a 20-mesh sieve to obtain agricultural organic waste powder. 2) Mix Trichoderma reesei and Proteobacterium chrysosporium at a mass ratio of 1:1 to obtain a composting agent; 3) The agricultural organic waste powder and the composting agent are mixed at a mass ratio of 48:1, the moisture content is controlled at 40%, and the mixture is composted at 40°C for 7 days to obtain the composted agricultural organic waste. 3. Preparation of compound microbial agents The composite microbial agent was obtained by mixing Azotobacter chrysogenum, Bacillus circulans, and Nocardia brasiliensis in a mass ratio of 4:1:0.5. 4. Preparation of composite silicon-calcium-magnesium soil conditioner 1) Weigh each raw material according to the following mass proportions: 20 parts activated silicon-calcium-magnesium powder, 40 parts decomposed agricultural organic waste, and 5 parts compound microbial inoculant; 2) Mix the decomposed agricultural organic waste weighed in step 1) with the compound microbial agent to obtain a premix; 3) Mix the premix obtained in step 2) with the activated silicon-calcium-magnesium powder weighed in step 1) to obtain the composite silicon-calcium-magnesium soil conditioner.

[0038] Example 3 A composite silicon-calcium-magnesium soil conditioner 1. Preparation of activated silicon-calcium-magnesium powder 1) Mix the quartz sand, calcite powder and magnesite powder in a mass ratio of 3:6:4 to obtain a premix. 2) According to the mass ratio of silane coupling agent, humic acid, nano iron oxide and water of 4:6:1.5:12, silane coupling agent, humic acid and nano iron oxide are placed in water, the stirring speed is controlled at 200 rpm, and the mixture is mixed at room temperature for 5 min to obtain an activated suspension. 3) According to the mass ratio of premix to activation suspension of 6:1, place the premix obtained in step 1) into the activation suspension obtained in step 2), control the stirring speed at 300 rpm, and mix at room temperature for 35 min to obtain the activator mixed premix. 4) The activator mixture premix obtained in step 3) is activated, crushed, and passed through a 100-mesh sieve to obtain the activated material; The activation treatment specifically involves: heating to 450°C in an air atmosphere at a controlled heating rate of 5°C / min, holding the temperature for 60 min, and then heating to 650°C at a controlled heating rate of 10°C / min, holding the temperature for 2.5 h. 5) According to the mass ratio of sodium alginate, polyvinyl alcohol, citric acid and water of 1.5∶2∶0.5∶90, control the stirring speed at 300 rpm, first heat the water to 85℃, then add polyvinyl alcohol to the water. After the polyvinyl alcohol is completely dissolved, cool down to 50℃, add sodium alginate and citric acid, and dissolve completely to obtain the embedding solution. 6) Using fluidized bed spray coating technology, the activated material obtained in step 4) is embedded in the embedding liquid obtained in step 5) at a mass ratio of 1:0.6 between the activated material and the embedding liquid, and dried until the water content is less than 10% to obtain the activated silicon-calcium-magnesium powder. The parameters for the fluidized bed spray coating technology are: inlet air temperature 60℃, spray rate 15mL / min, and atomization pressure 0.4MPa. 2. Preparation of composted agricultural organic waste 1) Mix rice straw, sugarcane residue and silkworm excrement in a mass ratio of 1:1:1, crush them, and pass them through a 20-mesh sieve to obtain agricultural organic waste powder. 2) Mix Trichoderma reesei and Proteobacterium chrysosporium at a mass ratio of 1:1 to obtain a composting agent; 3) The agricultural organic waste powder and the composting agent are mixed at a mass ratio of 51:1, the moisture content is controlled at 60%, and the mixture is composted at 40°C for 14 days to obtain the composted agricultural organic waste. 3. Preparation of compound microbial agents The composite microbial agent was obtained by mixing Azotobacter chrysogenum, Bacillus circulans, and Nocardia brasiliensis in a mass ratio of 6:3:1.5. 4. Preparation of composite silicon-calcium-magnesium soil conditioner 1) Weigh each raw material according to the following mass proportions: 30 parts activated silicon-calcium-magnesium powder, 60 parts decomposed agricultural organic waste, and 15 parts compound microbial inoculant; 2) Mix the decomposed agricultural organic waste weighed in step 1) with the compound microbial agent to obtain a premix; 3) Mix the premix obtained in step 2) with the activated silicon-calcium-magnesium powder weighed in step 1) to obtain the composite silicon-calcium-magnesium soil conditioner.

[0039] Comparative Example 1 A soil conditioner Same as Example 1, except that the preparation of the activated silicon-calcium-magnesium powder in step 1 is as follows: 1) Mix the quartz sand, calcite powder and magnesite powder in a mass ratio of 2:5:3 to obtain a premix; 2) According to the mass ratio of humic acid, nano-ferric oxide and water of 5:1:10, humic acid and nano-ferric oxide are placed in water, the stirring speed is controlled at 150 rpm, and the mixture is mixed at room temperature for 4 min to obtain an activated suspension. 3) According to the mass ratio of premix to activation suspension of 5:1, place the premix obtained in step 1) into the activation suspension obtained in step 2), control the stirring speed to 250 rpm, and mix at room temperature for 30 min to obtain the activator mixed premix. 4) The activator mixture premix obtained in step 3) is activated, crushed, and passed through a 100-mesh sieve to obtain the activated material; The activation treatment specifically involves: in an air atmosphere, controlling the heating rate at 5℃ / min, heating to 400℃, holding and calcining for 40 min, and then controlling the heating rate at 10℃ / min, heating to 600℃, and holding and calcining for 2 h. 5) According to the mass ratio of sodium alginate, polyvinyl alcohol, citric acid and water of 1:1.5:0.2:85, control the stirring speed at 250 rpm, first heat the water to 83°C, then add polyvinyl alcohol to the water. After the polyvinyl alcohol is completely dissolved, cool down to 45°C, add sodium alginate and citric acid, and dissolve completely to obtain the embedding solution. 6) Using fluidized bed spray coating technology, the activated material obtained in step 4) is embedded in the embedding liquid obtained in step 5) at a mass ratio of 1:0.5 between the activated material and the embedding liquid, and dried until the water content is less than 10% to obtain the activated silicon-calcium-magnesium powder. The parameters for fluidized bed spray coating technology are: inlet air temperature 55℃, spray rate 10mL / min, and atomization pressure 0.3MPa.

[0040] Comparative Example 2 A soil conditioner Same as Example 1, except that the preparation of the activated silicon-calcium-magnesium powder in step 1 is as follows: 1) Mix the quartz sand, calcite powder and magnesite powder in a mass ratio of 2:5:3 to obtain a premix; 2) According to the mass ratio of silane coupling agent, nano-iron oxide and water of 3:1:10, silane coupling agent and nano-iron oxide are placed in water, the stirring speed is controlled at 150 rpm, and the mixture is mixed at room temperature for 4 min to obtain an activated suspension. 3) According to the mass ratio of premix to activation suspension of 5:1, place the premix obtained in step 1) into the activation suspension obtained in step 2), control the stirring speed to 250 rpm, and mix at room temperature for 30 min to obtain the activator mixed premix. 4) The activator mixture premix obtained in step 3) is activated, crushed, and passed through a 100-mesh sieve to obtain the activated material; The activation treatment specifically involves: in an air atmosphere, controlling the heating rate at 5℃ / min, heating to 400℃, holding and calcining for 40 min, and then controlling the heating rate at 10℃ / min, heating to 600℃, and holding and calcining for 2 h. 5) According to the mass ratio of sodium alginate, polyvinyl alcohol, citric acid and water of 1:1.5:0.2:85, control the stirring speed at 250 rpm, first heat the water to 83°C, then add polyvinyl alcohol to the water. After the polyvinyl alcohol is completely dissolved, cool down to 45°C, add sodium alginate and citric acid, and dissolve completely to obtain the embedding solution. 6) Using fluidized bed spray coating technology, the activated material obtained in step 4) is embedded in the embedding liquid obtained in step 5) at a mass ratio of 1:0.5 between the activated material and the embedding liquid, and dried until the water content is less than 10% to obtain the activated silicon-calcium-magnesium powder. The parameters for fluidized bed spray coating technology are: inlet air temperature 55℃, spray rate 10mL / min, and atomization pressure 0.3MPa.

[0041] Comparative Example 3 A soil conditioner Same as Example 1, except that the preparation of the activated silicon-calcium-magnesium powder in step 1 is as follows: 1) Mix the quartz sand, calcite powder and magnesite powder in a mass ratio of 2:5:3 to obtain a premix; 2) According to the mass ratio of silane coupling agent, humic acid and water of 3:5:10, silane coupling agent and humic acid are placed in water, the stirring speed is controlled at 150 rpm, and the mixture is mixed at room temperature for 4 min to obtain an activated suspension. 3) According to the mass ratio of premix to activation suspension of 5:1, place the premix obtained in step 1) into the activation suspension obtained in step 2), control the stirring speed to 250 rpm, and mix at room temperature for 30 min to obtain the activator mixed premix. 4) The activator mixture premix obtained in step 3) is activated, crushed, and passed through a 100-mesh sieve to obtain the activated material; The activation treatment specifically involves: in an air atmosphere, controlling the heating rate at 5℃ / min, heating to 400℃, holding and calcining for 40 min, and then controlling the heating rate at 10℃ / min, heating to 600℃, and holding and calcining for 2 h. 5) According to the mass ratio of sodium alginate, polyvinyl alcohol, citric acid and water of 1:1.5:0.2:85, control the stirring speed at 250 rpm, first heat the water to 83°C, then add polyvinyl alcohol to the water. After the polyvinyl alcohol is completely dissolved, cool down to 45°C, add sodium alginate and citric acid, and dissolve completely to obtain the embedding solution. 6) Using fluidized bed spray coating technology, the activated material obtained in step 4) is embedded in the embedding liquid obtained in step 5) at a mass ratio of 1:0.5 between the activated material and the embedding liquid, and dried until the water content is less than 10% to obtain the activated silicon-calcium-magnesium powder. The parameters for fluidized bed spray coating technology are: inlet air temperature 55℃, spray rate 10mL / min, and atomization pressure 0.3MPa.

[0042] Comparative Example 4 A soil conditioner Same as Example 1, except that the preparation of the activated silicon-calcium-magnesium powder in step 1 is as follows: 1) Mix the quartz sand, calcite powder and magnesite powder in a mass ratio of 2:5:3 to obtain a premix; 2) According to the mass ratio of silane coupling agent, humic acid, nano iron oxide and water of 3:5:1:10, silane coupling agent, humic acid and nano iron oxide are placed in water, the stirring speed is controlled at 150 rpm, and the mixture is mixed at room temperature for 4 min to obtain an activated suspension. 3) According to the mass ratio of premix to activation suspension of 5:1, place the premix obtained in step 1) into the activation suspension obtained in step 2), control the stirring speed to 250 rpm, and mix at room temperature for 30 min to obtain the activator mixed premix. 4) The activator mixture premix obtained in step 3) is activated, crushed, and passed through a 100-mesh sieve to obtain the activated material; The activation treatment specifically involves: heating to 600°C in an air atmosphere at a controlled heating rate of 10°C / min, and holding the temperature for 2.5 hours. 5) According to the mass ratio of sodium alginate, polyvinyl alcohol, citric acid and water of 1:1.5:0.2:85, control the stirring speed at 250 rpm, first heat the water to 83°C, then add polyvinyl alcohol to the water. After the polyvinyl alcohol is completely dissolved, cool down to 45°C, add sodium alginate and citric acid, and dissolve completely to obtain the embedding solution. 6) Using fluidized bed spray coating technology, the activated material obtained in step 4) is embedded in the embedding liquid obtained in step 5) at a mass ratio of 1:0.5 between the activated material and the embedding liquid, and dried until the water content is less than 10% to obtain the activated silicon-calcium-magnesium powder. The parameters for fluidized bed spray coating technology are: inlet air temperature 55℃, spray rate 10mL / min, and atomization pressure 0.3MPa.

[0043] Comparative Example 5 A soil conditioner Same as Example 1, except that the preparation of the activated silicon-calcium-magnesium powder in step 1 is as follows: 1) Mix the quartz sand, calcite powder and magnesite powder in a mass ratio of 2:5:3 to obtain a premix; 2) According to the mass ratio of silane coupling agent, humic acid, nano iron oxide and water of 3:5:1:10, silane coupling agent, humic acid and nano iron oxide are placed in water, the stirring speed is controlled at 150 rpm, and the mixture is mixed at room temperature for 4 min to obtain an activated suspension. 3) According to the mass ratio of premix to activation suspension of 5:1, place the premix obtained in step 1) into the activation suspension obtained in step 2), control the stirring speed to 250 rpm, and mix at room temperature for 30 min to obtain the activator mixed premix. 4) The activator mixture premix obtained in step 3) is activated, crushed, and passed through a 100-mesh sieve to obtain the activated material, namely the activated silicon-calcium-magnesium powder. The activation treatment specifically involves: heating to 400°C in an air atmosphere at a controlled heating rate of 5°C / min, holding the temperature for 40 min, and then heating to 600°C at a controlled heating rate of 10°C / min for 2 h.

[0044] Comparative Example 6 A soil conditioner Same as Example 1, except that the preparation of the compound microbial agent in step 3 is as follows: The compound microbial agent was obtained by mixing Azotobacter chrysogenum (replaced with BNCC 137688 purchased from Beina Biotechnology), Bacillus circulatoryus, and Nocardia brasiliensis in a mass ratio of 5:2:1.

[0045] Comparative Example 7 A soil conditioner Same as Example 1, except that the preparation of the compound microbial agent in step 3 is as follows: The compound microbial agent was obtained by mixing Azotobacter chrysogenum, Bacillus circulans (replaced with CGMCC 1.8808 purchased from China General Microbiological Culture Collection Center) and Nocardia brasiliensis in a mass ratio of 5:2:1.

[0046] Comparative Example 8 A soil conditioner Same as Example 1, except that the preparation of the compound microbial agent in step 3 is as follows: The compound microbial agent was obtained by mixing Azotobacter chrysogenum, Bacillus circulatoryus, and Nocardia brasiliensis (replaced with BNCC360427 purchased from Beina Biotechnology) in a mass ratio of 5:2:1.

[0047] Effect verification Physicochemical property testing Using an acidic soil (pH=4.8) as the test soil, the soil conditioners prepared in Examples 1-3 and Comparative Examples 1-8 of this invention were applied at a rate of 100 kg / mu. The physicochemical properties of the soil were tested 30 days after the application was completed. The test results are shown in Table 2. Table 2 Results of Physicochemical Properties Test

[0048] As shown in Table 2, the composite silicon-calcium-magnesium soil conditioner for acidic soil provided by this invention, after 30 days of conditioning, can improve the soil pH to 6.5, exchangeable aluminum to 0.1 cmol / kg, available phosphorus to 21.7 mg / kg, exchangeable calcium to 7.8 cmol / kg, and organic matter to 25.2 g / kg, effectively improving the physicochemical properties of acidic soil. As shown in Table 2, omitting activation, omitting encapsulation treatment, or changing the strains of the compound microbial agent will all have adverse effects on the physicochemical properties.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A composite silicon-calcium-magnesium soil conditioner for acidic soils, characterized in that, Includes the following quantities of raw materials: 20-30 parts activated silicon-calcium-magnesium powder, 40-60 parts decomposed agricultural organic waste, and 5-15 parts compound microbial agent.

2. The composite silicon-calcium-magnesium soil conditioner for acidic soil according to claim 1, characterized in that, The preparation method of the activated silicon-calcium-magnesium powder includes the following steps: 1) Mix quartz sand, calcite powder and magnesite powder to obtain a premix; 2) Place the silane coupling agent, humic acid, and nano-ferric oxide in water and mix to obtain an activated suspension; 3) Place the premix obtained in step 1) into the activated suspension obtained in step 2) and mix to obtain the activator mixed premix; 4) The activator mixture premix obtained in step 3) is activated by crushing and sieving to obtain the activated material; 5) Dissolve sodium alginate, polyvinyl alcohol, and citric acid in water to obtain an embedding solution; 6) Using fluidized bed spray coating technology, the activated material obtained in step 4) is embedded in the embedding liquid obtained in step 5), and dried to obtain the activated silicon-calcium-magnesium powder.

3. The composite silicon-calcium-magnesium soil conditioner for acidic soil according to claim 2, characterized in that, In step 1), the mass ratio of the quartz sand, calcite powder, and magnesite powder is (1-3):(4-6):(2-4); In step 2), the mass ratio of the silane coupling agent, humic acid, nano-ferric oxide and water is (2-4):(4-6):(0.5-1.5):(8-12); the mixing is specifically carried out by controlling the stirring speed to 100-200 rpm and mixing at room temperature for 3-5 minutes.

4. A composite silicon-calcium-magnesium soil conditioner for acidic soils according to claim 2, characterized in that, In step 3), the mass ratio of the premix to the activated suspension is (4-6):1; the mixing process specifically involves controlling the stirring speed at 200-300 rpm and mixing at room temperature for 25-35 minutes. In step 4), the activation treatment specifically involves: in an air atmosphere, controlling the heating rate at 5℃ / min, heating to 350-450℃, holding at that temperature for 30-60 minutes, and then controlling the heating rate at 10℃ / min, heating to 550-650℃, and holding at that temperature for 1.5-2.5 hours.

5. A composite silicon-calcium-magnesium soil conditioner for acidic soils according to claim 2, characterized in that, In step 5), the mass ratio of sodium alginate, polyvinyl alcohol, citric acid, and water is (0.5-1.5):(1-2):(0.1-0.5):(80-90); the dissolution process specifically involves controlling the stirring speed at 200-300 rpm, first heating the water to 80-85°C, then adding polyvinyl alcohol to the water. After the polyvinyl alcohol is completely dissolved, the temperature is lowered to 40-50°C, and sodium alginate and citric acid are added and completely dissolved. In step 6), the mass ratio of the activated material to the encapsulating liquid is 1:(0.4-0.6); the parameters of the fluidized bed spray coating technology are: inlet air temperature 50-60℃, spray rate 5-15mL / min, and atomization pressure 0.2-0.4MPa.

6. A composite silicon-calcium-magnesium soil conditioner for acidic soils according to claim 1, characterized in that, The method for preparing the decomposed agricultural organic waste includes the following steps: 1) Mix rice straw, sugarcane residue and silkworm excrement, crush and sieve to obtain agricultural organic waste powder; 2) Mix Trichoderma reesei and Protocormia chrysospora to obtain a composting agent; 3) Mix agricultural organic waste powder with composting microbial agent and compost to obtain the composted agricultural organic waste.

7. A composite silicon-calcium-magnesium soil conditioner for acidic soils according to claim 1, characterized in that, In step 1), the mass ratio of rice straw, sugarcane residue, and silkworm excrement is 1:1:1; In step 2), the mass ratio of Trichoderma reesei to Procambarus chrysospora is 1:1; In step 3), the mass ratio of the agricultural organic waste powder to the composting agent is (48-51):1; the composting specifically involves controlling the moisture content to be 40%-60% and composting at 40℃ for 7-14 days.

8. A composite silicon-calcium-magnesium soil conditioner for acidic soils according to claim 1, characterized in that, The compound microbial agent is composed of *Azotobacter chrysogenum*, *Bacillus circulans*, and *Nocardia brasiliensis* in a mass ratio of (4–6): (1–3): (0.5–1.5).

9. A method for preparing a composite silicon-calcium-magnesium soil conditioner for acidic soil as described in any one of claims 1 to 8, characterized in that, Includes the following steps: 1) Mix well-rotted agricultural organic waste and compound microbial inoculant to obtain a premix; 2) Mix the premix obtained in step 1) with the activated silicon-calcium-magnesium powder to obtain the composite silicon-calcium-magnesium soil conditioner.

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