Organic-inorganic composite material acidified soil conditioner and preparation method thereof

Abstract

The invention belongs to the technical field of soil improvement, and relates to an organic-inorganic composite material acidified soil conditioner and a preparation method thereof.The preparation method comprises the following steps that firstly, magnesium carbonate, calcium carbonate, talcum powder, silicon dioxide and plant ash are mixed to obtain an inorganic material; step 2, mixing and fermenting livestock manure, plant straw, coco coir, soybean meal, seaweed meal, biochar and compound bacteria powder to obtain an organic material; and step 3, fully mixing the inorganic material and the organic material, and coating to obtain the organic-inorganic composite material acidified soil conditioner. Through organic-inorganic composite system design, segmented fermentation control and an environment-friendly coating technology, the core defects that an existing acid soil conditioner is limited in single material function, insufficient in organic-inorganic synergism, risk in secondary acidification in the fermentation process, uncontrollable in nutrient release and the like are systematically overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of soil improvement and relates to an organic-inorganic composite material acidified soil conditioner and a preparation method thereof. Background Art

[0002] The normal growth and development of crops depends on a healthy soil environment. However, in nature, the soils in which crops grow often present various obstacles, such as acidic soils. Because protons in soil participate in almost all chemical reaction cycles, soil acidification can disrupt proton balance, thereby affecting the transformation of elemental forms in the soil. Generally speaking, the pH value of soil suitable for most crops is between slightly acidic and neutral. Although different crops have different tolerances to soil pH, soil acidification still significantly affects the normal growth and development of crop roots. The use of soil conditioners can improve the physical and chemical properties of the soil, making it easier for crops to absorb water and nutrients from the soil, providing favorable conditions for the growth of soil microorganisms, and further improving soil productivity.

[0003] At present, common acidic soil conditioners include the following categories: 1) Lime conditioners, such as quicklime and slaked lime, which increase the pH value by quickly neutralizing hydrogen ions. They are the most commonly used acidic soil conditioners. However, long-term use will lead to excessive calcium ions, destroying the soil aggregate structure and causing soil compaction. In addition, high calcium may inhibit the absorption of elements such as magnesium and potassium by crops, affecting their growth.

[0004] 2) Organic conditioners, such as compost and biochar, improve soil structure and promote microbial activity by increasing organic matter. Organic decomposition may produce short-chain organic acids, resulting in weak acid neutralization ability. Long-term application is required to significantly increase the pH value, which cannot meet the needs of rapid improvement.

[0005] 3) Composite conditioners simply mix inorganic and organic materials, but due to the improper ratio of inorganic and organic components, functional conflicts occur. For example, organic matter adsorbs calcium ions, reducing neutralization efficiency. Without modification based on the material properties, there is a risk of secondary pollution.

[0006] Therefore, it is urgent to provide a multifunctional organic-inorganic composite conditioner that has quick and long-lasting effects and can also take into account fertilization and other functions. Summary of the Invention

[0007] In order to solve the above problems, the present invention provides a method for preparing an organic-inorganic composite material acidifying soil conditioner.

[0008] Step 1: Magnesium carbonate, calcium carbonate, talc, silicon dioxide and wood ash are mixed and crushed to D50≤500nm, and then mixed with sodium carboxymethyl cellulose solution at a solid-liquid mass ratio of 1:3, and ultrasonicated at 50-60kHz for 40-60min to obtain an inorganic material.

[0009] Preferably, the mass ratio of the magnesium carbonate, calcium carbonate, talc, silicon dioxide and wood ash is 3:7:5:6:3.

[0010] Preferably, the mass fraction of the sodium carboxymethyl cellulose solution is 0.5-1%.

[0011] Step 2: Mix and grind livestock manure, plant straw, coconut husk, soybean meal, seaweed powder, biochar and composite bacterial powder, pass through a 20-30 mesh sieve, add molasses water to adjust the moisture content to 60-70%, and ferment at 40-50°C, 50-60% humidity, and 8% oxygen content or more for 3-5 days; at 45-55°C, 55-65% humidity, and oxygenate for 20-30 minutes every 4-5 hours, with an oxygen flow rate of 0.4-0.5m 3 / h, and ferment for 4-6 days with an oxygen content of 1-3% during the rest of the time; ferment for 6-7 days at 50-60°C, 60-65% humidity, and an oxygen content ≤8%, add humic acid after the fermentation is completed, and age at 50-60°C for 1.5-2 days to obtain organic materials.

[0012] Preferably, the mass ratio of the livestock manure, plant straw, coconut husk, soybean meal, seaweed powder, biochar, and composite bacterial powder is 15:10:8:12:9:6:2. Most preferably, the composite bacterial powder includes Bacillus subtilis powder, Trichoderma powder, Lactobacillus powder, and yeast powder in a mass ratio of 3:2:1:1.

[0013] Preferably, the mass ratio of molasses to water in the molasses water is 1:9.

[0014] Preferably, the humic acid accounts for 5-6% of the total mass of the fermentation product.

[0015] Step 3: After the inorganic material and the organic material are fully mixed, they are dried at 50-60° C. to a moisture content of ≤8%, and then granulated to obtain a primary product with a particle size of 3-5 mm. The primary product is placed in a coating tower and coated with a coating agent. The inlet air temperature is 45-55° C. and the coating thickness is 50-100 μm. After the coating is completed, an organic-inorganic composite material acidified soil conditioner is obtained.

[0016] Preferably, the mass ratio of the inorganic material to the organic material is (2-5):(8-12), and most preferably, the mass ratio of the inorganic material to the organic material is 1:3.

[0017] Preferably, the coating agent comprises chitosan, calcium alginate, polylactic acid, urea, potassium dihydrogen phosphate and water in a mass ratio of 5:3:5:4:3:100.

[0018] The present invention has the following advantages:

[0019] (1) Synergistic effect of organic-inorganic composite system, inorganic materials quickly release alkaline substances to neutralize H + , organic materials (fermentation products, humic acid) continuously provide organic matter, improve soil structure and microbial environment, avoid nutrient competition, achieve functional complementarity, and solve the problem of poor improvement effect of existing compound conditioners due to unreasonable ratios.

[0020] (2) The three-stage fermentation of the present invention ensures that organic matter is fully decomposed, avoids the production of short-chain organic acids such as acetic acid and propionic acid, and prevents secondary acidification. The composite bacterial powder accelerates the degradation of cellulose, generates stable humus, and enhances the soil's fertilizer retention capacity, thus solving the problem that traditional composting often produces acidic substances due to incomplete fermentation.

[0021] (3) The present invention forms a semipermeable membrane through a coating agent to control the slow release of nutrients and reduce the application frequency. Degradable materials such as polylactic acid avoid plastic coating pollution, which meets the needs of green agriculture and solves the problem that traditional granular conditioners have no coating or use non-degradable materials, which easily cause nutrient loss or environmental pollution. DETAILED DESCRIPTION

[0022] The following is a clear and complete description of the technical solutions in the embodiments of the invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0023] Example 1

[0024] Step 1: Magnesium carbonate, calcium carbonate, talc, silicon dioxide and wood ash are mixed in a mass ratio of 3:7:5:6:3 and crushed until D50 is ≤ 500 nm, and then mixed with a 0.8% sodium carboxymethyl cellulose solution in a solid-liquid mass ratio of 1:3, and ultrasonicated at 50 kHz for 50 minutes to obtain an inorganic material.

[0025] Step 2: Cow dung, corn stalks, coconut husk, soybean meal, seaweed powder, biochar and composite bacteria powder are mixed and crushed in a mass ratio of 15:10:8:12:9:6:2, passed through a 25-mesh sieve, and molasses water is added to adjust the moisture content to 65%. Ferment at 40°C, 50% humidity, and 8% oxygen content for 4 days; at 50°C, 660% humidity, and oxygenation for 30 minutes every 4 hours, with an oxygenation rate of 0.4m 3 / h, with the remaining time spent fermenting at an oxygen content of 2% for 5 days; then fermenting at 55°C, 65% humidity, and an oxygen content of ≤8% for 6 days. After fermentation, humic acid was added, and the mixture was aged at 55°C for 2 days to obtain an organic material. The composite bacterial powder includes Bacillus subtilis powder, Trichoderma powder, Lactobacillus powder, and yeast powder in a mass ratio of 3:2:1:1. These powders are all commercially available. The mass ratio of molasses to water in the molasses water is 1:9. The humic acid accounts for 5-6% of the total mass of the fermented product.

[0026] Step 3: After the inorganic material and the organic material are thoroughly mixed in a mass ratio of 1:3, the mixture is dried at 55°C to a moisture content of ≤8%, and then granulated to obtain a primary product with a particle size of 3-5 mm. The primary product is placed in a coating tower and coated with a coating agent at an inlet air temperature of 50°C and a coating thickness of 95-100 μm. After the coating is completed, an organic-inorganic composite material acidified soil conditioner is obtained. The coating agent includes chitosan, calcium alginate, polylactic acid, urea, potassium dihydrogen phosphate, and water in a mass ratio of 5:3:5:4:3:100.

[0027] Test Example 1

[0028] 1. Collect field acidic soil samples and test their physical and chemical properties: pH = 4.2, organic matter content = 1.2%, available phosphorus = 12 mg / kg, available potassium = 85 mg / kg, total nitrogen = 0.8 g / kg, Cr 3+ Content = 5.2 mg / kg.

[0029] 2. Experimental Grouping

[0030] Blank group: no conditioning agent was administered.

[0031] Control group: lime was applied at a rate of 2 kg / m 2 .

[0032] Experimental group: Conditioner prepared according to the method of Example 1, dosage is 2kg / m 2 .

[0033] 3. Soil treatment and cultivation

[0034] Mix the conditioner evenly into the soil and maintain the soil moisture content at 60% of the field capacity.

[0035] Place in a greenhouse for cultivation at a temperature of 25±2℃ and regularly turn the soil for ventilation.

[0036] 4. Measurement indicators and cycles

[0037] Samples were taken at 0 days, 30 days, 60 days, and 90 days after application, and the following indicators were measured:

[0038] Soil pH was determined by potentiometric method, organic matter content was determined by potassium dichromate oxidation method, available phosphorus was determined by spectrophotometry, available potassium was determined by flame photometry, total nitrogen was determined by Kjeldahl method, and Cr was determined by atomic absorption spectrometry. 3+ content.

[0039] Table 1 Changes in soil pH and organic matter

[0040] pH (0 day) pH (30 days) pH (60 days) pH (90 days) Organic matter (90 days) Blank group 4.2 4.1 4.0 4.0 1.3 control group 4.2 5.8 5.5 5.0 1.5 Experimental group 4.2 6.3 6.6 6.9 3.8

[0041] Table 2 Changes in soil nutrient content (90 days)

[0042] Available phosphorus (mg / kg) Fast-acting potassium (mg / kg) Total nitrogen (g / kg) Blank group 12 85 0.8 control group 28 120 1.2 Experimental group 45 185 2.5

[0043] Table 3Cr 3+ Passivation effect

[0044] <![CDATA[Cr 3+ Content (mg / kg)]]> Passivation rate (%) Blank group 5.2 - control group 4.8 7.7 Experimental group 1.6 69.2

[0045] As shown in Table 1-3, the conditioner of the present invention can increase the soil pH from 4.2 to 6.3 within 30 days, and it is still stable at 6.9 after 90 days, which is significantly better than the traditional conditioner. The conditioner of the present invention can significantly improve the soil nutrients, and the available phosphorus, available potassium and total nitrogen contents are 45mg / kg, 185mg / kg and 2.5g / kg respectively, which are 1.6-2.1 times that of the traditional conditioner. The conditioner of the present invention can effectively passivate heavy metals, Cr 3+ The passivation rate reaches 69.2%, which is much higher than traditional conditioners.

[0046] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an organic-inorganic composite material acidifying soil conditioner, characterized in that: The following steps are involved: Step 1: Magnesium carbonate, calcium carbonate, talc, silicon dioxide and wood ash are mixed and ground, then mixed with sodium carboxymethyl cellulose solution, and ultrasonically treated to obtain an inorganic material; Step 2: livestock manure, plant straw, coconut husk, soybean meal, seaweed powder, biochar and composite bacterial powder are mixed and crushed, sieved, molasses water is added to adjust the moisture content, and fermented at 40-60° C. and 50-65% humidity for 13-18 days. After the fermentation is completed, humic acid is added and the mixture is aged at 50-60° C. for 1.5-2 days to obtain an organic material; Step 3: After the inorganic material and the organic material are fully mixed, they are dried to a moisture content of ≤8%, and then granulated to obtain a primary product. The primary product is placed in a coating tower and coated with a coating agent. The inlet air temperature is 45-55° C. and the coating thickness is 50-100 μm. After the coating is completed, an organic-inorganic composite material acidified soil conditioner is obtained.

2. The method for preparing an organic-inorganic composite material acidifying soil conditioner according to claim 1, characterized in that: The mass ratio of magnesium carbonate, calcium carbonate, talc, silicon dioxide and wood ash in step 1 is 3:7:5:6:

3.

3. The method for preparing an organic-inorganic composite material acidifying soil conditioner according to claim 1, characterized in that: The mass fraction of the sodium carboxymethyl cellulose solution in step 1 is 0.5-1%.

4. The method for preparing an organic-inorganic composite material acidifying soil conditioner according to claim 1, characterized in that: The fermentation process in step 2 is as follows: fermentation for 3-5 days at 40-50°C, humidity 50-60%, oxygen content ≥ 8%; fermentation for 20-30 minutes every 4-5 hours at 45-55°C, humidity 55-65%, oxygenation at a rate of 0.4-0.5m 3 / h, and ferment for 4-6 days with an oxygen content of 1-3% during the rest of the time; ferment for 6-7 days at 50-60℃, 60-65% humidity, and an oxygen content ≤8%.

5. The method for preparing an organic-inorganic composite material acidifying soil conditioner according to claim 1, characterized in that: The mass ratio of the livestock manure, plant straw, coconut bran, soybean meal, seaweed powder, biochar and composite bacterial powder in step 2 is 15:10:8:12:9:6:

2.

6. The method for preparing an organic-inorganic composite material acidifying soil conditioner according to claim 1, characterized in that: The composite bacterial powder in step 2 includes Bacillus subtilis powder, Trichoderma powder, Lactobacillus powder and yeast powder, with a mass ratio of 3:2:1:

1.

7. The method for preparing an organic-inorganic composite material acidifying soil conditioner according to claim 1, characterized in that: The mass ratio of molasses to water in the molasses water in step 2 is 1:9, and the humic acid accounts for 5-6% of the total mass of the fermentation product.

8. The method for preparing an organic-inorganic composite material acidifying soil conditioner according to claim 1, characterized in that: The mass ratio of the inorganic material to the organic material in step 3 is (2-5):(8-12).

9. The method for preparing an organic-inorganic composite material acidifying soil conditioner according to claim 1, characterized in that: The coating agent in step three includes chitosan, calcium alginate, polylactic acid, urea, potassium dihydrogen phosphate and water in a mass ratio of 5:3:5:4:3:

100.

10. An organic-inorganic composite material acidified soil conditioner prepared by the method according to any one of claims 1 to 9.