Multifunctional composite calcium carbonate soil conditioner and preparation method thereof

Abstract

The application provides a multifunctional composite calcium carbonate soil modifier and a preparation method thereof, and belongs to the technical field of agricultural soil improvement and inorganic functional materials. The modifier is prepared by using heavy calcium carbonate as a base material, and is composed of biochar, modified diatomite, potassium humate and chitosan derivatives in cooperation through an integrated process of wet activation-dry compounding-low temperature granulation, and has the functions of acid regulation, soil loosening, water retention, nitrogen fixation, phosphorus dissolution, carbon increase and microorganism promotion. Experiments show that the product can steadily increase the pH of acidic soil from 4.5-4.9 to 6.0-7.0, increase the soil organic matter by 20-35%, and increase the effective viable bacterial count by 60-85%; the yield of rice, corn and vegetables is increased by 18-32%, the nitrogen utilization rate reaches 15-22%, and the product has the advantages of slow and long-acting, green and environmental protection, non-compaction and no yield reduction, and can be widely used for the improvement of red-yellow soil acidification, orchards, vegetable gardens and saline-alkali and acidic soil, and has outstanding market value.

Description

Technical Field

[0001] This invention relates to the field of agricultural soil improvement and inorganic functional materials technology, and in particular to a multifunctional composite calcium carbonate soil conditioner and its preparation method. Background Technology

[0002] Currently, domestic arable land soils face problems such as acidification, compaction, infertility, low organic matter content, and severe nutrient loss. Existing technologies have significant shortcomings: calcium carbonate alone can only adjust acidity, without the functions of fertilization, water retention, or carbon fixation; quicklime and silicon-calcium-potassium conditioners are too alkaline, easily burning seedlings and damaging microorganisms; humic acid and organic fertilizers are easily lost, slow to take effect, costly, and difficult to store; simple physical mixing of minerals and organic matter results in poor binding force, slow onset of effect, and uneven distribution; and it is impossible to simultaneously achieve a synergistic effect of acidification, fertilization, fertilizer supply, soil improvement, and yield increase.

[0003] Therefore, developing a new type of composite soil conditioner with calcium carbonate as the main component, multiple functions, simple process, and low cost is an urgent need for modern agriculture. Summary of the Invention

[0004] The purpose of this invention is to provide a multifunctional composite calcium carbonate soil conditioner and its preparation method, so as to solve the above-mentioned technical problems.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a multifunctional composite calcium carbonate soil conditioner, prepared from raw materials comprising the following parts by weight: 60-80 parts of heavy calcium carbonate; 5-15 parts of biochar; 5-10 parts of modified diatomaceous earth; 3-8 parts of potassium humate; 1-3 parts of chitosan derivative; Dispersant 0.2~0.5 parts; 1-2 parts adhesive.

[0006] Furthermore, the heavy calcium carbonate contains ≥95% CaCO3 and has a D50 of 10~50μm.

[0007] Furthermore, the biochar is straw charcoal with a specific surface area > 200 m² / g.

[0008] Furthermore, the modified diatomaceous earth is obtained by acid activation and has a porosity of ≥60%.

[0009] Furthermore, the adhesive is a starch paste.

[0010] This invention also provides a method for preparing a multifunctional composite calcium carbonate soil conditioner, comprising the following steps: 1) After mixing heavy calcium carbonate and phosphoric acid solution, the mixture is activated, and then biochar, modified diatomaceous earth and dispersant are added for dispersion treatment to obtain a mineral complex. 2) Potassium humate and chitosan derivatives are mixed in a mineral complex and organically coated. Then, the binder is sprayed onto the surface of the particles by spray granulation and dried to obtain a multifunctional composite calcium carbonate soil conditioner.

[0011] Furthermore, the activation treatment temperature is 60~80℃, and the mass concentration of the phosphoric acid solution is 10~20%.

[0012] Furthermore, the organic coating temperature is 50~65℃, the spray granulation particle size is 2~4mm, and the drying temperature is ≤70℃.

[0013] The beneficial effects of this invention are: 1. Mild acid adjustment, long-lasting stability: pH increases from 4.5~4.9 to 6.0~7.0 without rebounding for 90 days.

[0014] 2. Significantly increased organic matter and CEC: organic matter +20~35%, CEC +25~40%.

[0015] 3. Water-stable aggregates are increased by 35-50%, completely eliminating caking.

[0016] 4. Strong water and fertilizer retention: water retention +30~45%, nitrogen fertilizer loss -18~28%.

[0017] 5. Microbial levels increase by 60-85%, resulting in high soil health.

[0018] 6. Crop yield increases by 18-32%, and root systems become more developed.

[0019] 7. The process is simple, the cost is low, and it is easy to scale up. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the microstructure of the multifunctional composite calcium carbonate soil conditioner prepared in Example 1 of the present invention. Detailed Implementation

[0021] This invention provides a multifunctional composite calcium carbonate soil conditioner, prepared from raw materials comprising the following parts by weight: 60-80 parts of heavy calcium carbonate; 5-15 parts of biochar; 5-10 parts of modified diatomaceous earth; 3-8 parts of potassium humate; 1-3 parts of chitosan derivative; Dispersant 0.2~0.5 parts; 1-2 parts adhesive.

[0022] In this invention, the content of the heavy calcium carbonate is preferably 65-75 parts by mass, more preferably 68-72 parts, and even more preferably 70 parts.

[0023] In this invention, the biochar content is preferably 6 to 12 parts by mass, and more preferably 8 to 10 parts by mass.

[0024] In this invention, the content of the modified diatomaceous earth is preferably 6 to 9 parts by weight, and more preferably 7 to 8 parts by weight.

[0025] In this invention, the content of potassium humate is preferably 4 to 7 parts by weight, and more preferably 5 to 6 parts by weight.

[0026] In this invention, the content of the chitosan derivative is preferably 1.5 to 2.5 parts by weight, and more preferably 2 parts.

[0027] In this invention, the content of the dispersant is preferably 0.3 to 0.4 parts by weight.

[0028] In this invention, the content of the adhesive is preferably 1.2 to 1.8 parts by weight, and more preferably 1.5 parts by weight.

[0029] In this invention, the heavy calcium carbonate contains ≥95% CaCO3 and has a D50 of 10~50μm.

[0030] In this invention, the biochar is straw charcoal with a specific surface area >200m² / g.

[0031] In this invention, the modified diatomaceous earth is obtained by acid activation and has a porosity of ≥60%.

[0032] In this invention, the binder is starch paste and the dispersant is sodium polyacrylate.

[0033] This invention also provides a method for preparing a multifunctional composite calcium carbonate soil conditioner, comprising the following steps: 1) After mixing heavy calcium carbonate and phosphoric acid solution, the mixture is activated, and then biochar, modified diatomaceous earth and dispersant are added for dispersion treatment to obtain a mineral complex. 2) Potassium humate and chitosan derivatives are mixed in a mineral complex and organically coated. Then, the binder is sprayed onto the surface of the particles by spray granulation and dried to obtain a multifunctional composite calcium carbonate soil conditioner.

[0034] In this invention, the activation treatment temperature is 60~80℃, preferably 65~75℃, and more preferably 70℃; the mass concentration of the phosphoric acid solution is 10~20%, preferably 15%.

[0035] In this invention, the temperature of the organic coating is 50~65℃, preferably 55~60℃, and more preferably 56~59℃; the particle size of the spray granulation is 2~4mm, preferably 3mm; and the drying temperature is ≤70℃.

[0036] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0037] Example 1

[0038] Raw material ratio: 70 parts heavy calcium carbonate, 10 parts biochar, 8 parts modified diatomaceous earth, 6 parts potassium humate, 2 parts chitosan derivative, 0.3 parts dispersant (sodium polyacrylate), and 1.5 parts starch paste.

[0039] Preparation method: 1) Mix heavy calcium carbonate with a 15% phosphoric acid solution at a solid-liquid ratio of 1:0.3, activate at 70°C for 30 min, then add biochar, modified diatomaceous earth and dispersant, and disperse at high speed for 20 min to obtain a mineral complex.

[0040] 2) Add potassium humate and chitosan derivative to the mineral complex, stir and coat at 60°C for 40 min, then granulate using a spray granulator (particle size 3 mm), while simultaneously spraying starch paste onto the surface of the particles, and finally dry at 65°C until the moisture content is ≤5% to obtain the product. Figure 1 This is a schematic diagram of the microstructure of the soil conditioner prepared in this embodiment. As can be seen from the figure, the composite calcium carbonate conditioner of the present invention has a loose, flocculent aggregate structure, with rough and porous particle surfaces, uniform dispersion, and no obvious hard agglomerates, indicating that the calcium carbonate matrix has been uniformly coated by the modified components.

[0041] Example 2

[0042] 75 parts heavy calcium carbonate, 6 parts biochar, 8 parts modified diatomaceous earth, 5 parts potassium humate, 2 parts chitosan derivative, 0.3 parts dispersant (sodium polyacrylate), and 1.5 parts starch paste.

[0043] The preparation method is the same as in Example 1.

[0044] Features: It adjusts acidity faster and is suitable for strongly acidic soils.

[0045] Example 3

[0046] 65 parts heavy calcium carbonate, 14 parts biochar, 10 parts modified diatomaceous earth, 7 parts potassium humate, 3 parts chitosan derivative, 0.4 parts dispersant (sodium polyacrylate), and 1.8 parts starch paste.

[0047] The preparation method is the same as in Example 1.

[0048] Features: Excellent water and fertilizer retention, suitable for dry land and orchards.

[0049] Example 4

[0050] 68 parts of heavy calcium carbonate, 10 parts of biochar, 8 parts of modified diatomaceous earth, 9 parts of potassium humate, 3 parts of chitosan derivative, 0.3 parts of dispersant (sodium polyacrylate), and 1.5 parts of starch paste.

[0051] The preparation method is the same as in Example 1.

[0052] Features: Excellent for improving soil fertility, suitable for poor vegetable fields.

[0053] Example 5

[0054] Based on Example 1, the following were added: 1 part magnesium sulfate, 0.2 parts zinc sulfate, and 0.1 parts borax. Features: Supplements calcium while simultaneously providing magnesium, zinc, and boron, improving the quality of agricultural products.

[0055] Example 6

[0056] Reduce the amount of potassium humate and replace it with biochemical humic acid; otherwise, it remains the same as in Example 1. Features: Low salt content, does not damage roots, suitable for use during the seedling and early seedling stages.

[0057] Test soil: acidic red soil, pH=4.6; application rate: 50 kg / mu.

[0058] Table 1 Soil data 30 days after application of soil conditioner in the example.

[0059] Crop trials (rice / Chinese cabbage / corn)

[0060] Rice experiment using soil conditioner from Example 1

[0061] Yield per mu: 625 kg, an increase of 29.7%, and nitrogen fertilizer utilization rate increased by 20.3%.

[0062] Dryland maize experiment using soil conditioner from Example 3

[0063] Yield per mu: 728 kg, an increase of 26.4%, with significant improvement in drought resistance and water retention.

[0064] A soil conditioner experiment was conducted on Chinese cabbage using the soil conditioner from Example 4.

[0065] The germination rate was 95.3%, the fresh weight yield increased by 31.6%, and the leaves were dark green.

[0066] Comparative Example 1

[0067] Raw material ratio (parts by weight): 100 parts of heavy calcium carbonate (CaCO3≥95%, D50=30μm).

[0068] Preparation method: The control sample was prepared by directly pulverizing heavy calcium carbonate through a 200-mesh sieve without any activation treatment or organic modification.

[0069] Effects: Only raises pH; does not retain water, enrich fertilizer, improve granulation, or promote microbial growth. Extremely poor results.

[0070] Comparative Example 2

[0071] Raw material ratio (parts by weight): 100 portions of commercially available quicklime (CaO≥90%).

[0072] Preparation method: Quicklime is directly crushed and passed through a 100-mesh sieve. When using it, water is added to make a slurry before applying it to the soil.

[0073] Effects: pH spiked to 8.7, causing root burn, decreased germination rate, and a 40% reduction in microorganisms.

[0074] Comparative Example 3

[0075] Raw material ratio (parts by weight): 70 parts of heavy calcium carbonate (same as in Example 1), and 6 parts of ordinary humic acid raw material (unpurified, not potassium humate).

[0076] Preparation method: The heavy calcium carbonate and ordinary humic acid raw materials are simply dry-mixed using a three-dimensional mixer (mixing time 10 min), without phosphoric acid activation treatment, organic coating, or spray granulation, and applied directly as powder.

[0077] Effects: No activation or coating, easy to delaminate, slow to take effect, poor water retention, and the effect is less than 60% of that of this invention.

[0078] Comparative Example 4

[0079] Raw material ratio (parts by weight): 88 parts of heavy calcium carbonate (replacing 10 parts of biochar and 8 parts of diatomaceous earth in Example 1), 6 parts of potassium humate, 2 parts of chitosan derivative, 0.3 parts of dispersant (sodium polyacrylate), and 1.5 parts of binder (starch paste). That is, biochar and modified diatomaceous earth are completely omitted, and the remaining components and amounts are the same as in Example 1.

[0080] Preparation method: The preparation process is the same as in Example 1 (including phosphoric acid activation, organic coating, and spray granulation).

[0081] Effects: Water retention capacity decreased by 42%, CEC was low, and nutrients were easily leached away.

[0082] Comparative Example 5

[0083] Raw material ratio (parts by weight): 78 parts of heavy calcium carbonate (replacing 6 parts of potassium humate and 2 parts of chitosan derivative in Example 1), 10 parts of biochar, 8 parts of modified diatomaceous earth, 0.3 parts of dispersant (sodium polyacrylate), and 1.5 parts of binder (starch paste). That is, the organic active components (potassium humate and chitosan derivative) are completely omitted, and only the mineral components and binder are retained.

[0084] Preparation method: The preparation process is the same as in Example 1 (but the "organic coating" step is omitted, and the minerals are directly granulated after being activated and dispersed by phosphoric acid and then coated with starch paste).

[0085] Results: Microbial growth was less than 15%, granular structure was poor, and crop yield increased by less than 10%.

[0086] As can be seen from the above embodiments, the present invention provides a multifunctional composite calcium carbonate soil conditioner and its preparation method. This conditioner uses heavy calcium carbonate as the base material and is synergistically composed of composite biochar, modified diatomaceous earth, potassium humate, and chitosan derivatives. It is prepared through an integrated process of wet activation-dry compounding-low-temperature granulation, integrating multiple functions such as acid adjustment, soil loosening, water retention, nitrogen fixation, phosphorus solubilization, carbon increase, and microbial promotion. Experiments show that this product can stably raise the pH of acidic soil from 4.5-4.9 to 6.0-7.0, increase soil organic matter by 20-35%, increase cation exchange capacity (CEC) by 25-40%, increase water-stable aggregates by 35-50%, and increase the number of effective viable bacteria by 60-85%. It can also increase the yield of rice, corn, and vegetables by 18-32% and improve nitrogen fertilizer utilization by 15-22%. It has significant advantages such as slow and long-lasting effects, green and environmentally friendly properties, no soil compaction, and no yield reduction. It can be widely used for the improvement of acidified red and yellow soil, orchards, vegetable gardens, and saline-alkali acidic soils, and has outstanding market value.

[0087] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A multifunctional composite calcium carbonate soil conditioner, characterized in that, It is prepared from raw materials comprising the following parts by mass: 60-80 parts of heavy calcium carbonate; 5-15 parts of biochar; 5-10 parts of modified diatomaceous earth; 3-8 parts of potassium humate; 1-3 parts of chitosan derivative; Dispersant 0.2~0.5 parts; 1-2 parts adhesive.

2. The multifunctional composite calcium carbonate soil conditioner according to claim 1, characterized in that, The heavy calcium carbonate contains ≥95% CaCO3 and has a D50 of 10~50μm.

3. The multifunctional composite calcium carbonate soil conditioner according to claim 2, characterized in that, The biochar is straw charcoal with a specific surface area >200m² / g.

4. The multifunctional composite calcium carbonate soil conditioner according to claim 1 or 3, characterized in that, The modified diatomaceous earth is obtained by acid activation and has a porosity of ≥60%.

5. The multifunctional composite calcium carbonate soil conditioner according to claim 1, characterized in that, The adhesive is a starch paste.

6. The preparation method of the multifunctional composite calcium carbonate soil conditioner according to any one of claims 1 to 5, characterized in that, Includes the following steps: 1) After mixing heavy calcium carbonate and phosphoric acid solution, the mixture is activated, and then biochar, modified diatomaceous earth and dispersant are added for dispersion treatment to obtain a mineral complex. 2) Potassium humate and chitosan derivatives are mixed in a mineral complex and organically coated. Then, the binder is sprayed onto the surface of the particles by spray granulation and dried to obtain a multifunctional composite calcium carbonate soil conditioner.

7. The preparation method according to claim 6, characterized in that, The activation treatment is performed at a temperature of 60-80°C, and the mass concentration of the phosphoric acid solution is 10-20%.

8. The preparation method according to claim 6 or 7, characterized in that, The organic coating temperature is 50~65℃, the spray granulation particle size is 2~4mm, and the drying temperature is ≤70℃.

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