Soil conditioner for pepper planting and preparation method thereof

Abstract

The invention discloses a soil conditioner for pepper planting. The soil conditioner is prepared from the following components in parts by weight: 6 to 8 parts of continuous cropping soil, 1.5 to 2.5 parts of attapulgite, 0.5 to 1.5 parts of bentonite, 0.2 to 0.5 part of nano zinc oxide, 1 to 2 parts of chitosan oligosaccharide, 0.8 to 1.2 parts of EM (Effective Microorganisms) microbial inoculum and 0.1 to 0.3 part of graphene oxide. The composite application of the nano material and biomacromolecules is introduced into the soil conditioner, and the problems of agglomeration, weak antibacterial ability and the like are solved.

Description

Technical Field

[0001] This invention relates to the field of chili pepper cultivation technology, specifically to a soil conditioner for chili pepper cultivation and its preparation method. Background Technology

[0002] Chili peppers are an important economic crop in my country, widely cultivated in the southwest region, with Guizhou province having become the province with the largest planting area. However, with the expansion of chili pepper cultivation and continuous cropping year after year, the problem of continuous cropping obstacles has become increasingly prominent. Continuous cropping obstacles manifest as deterioration of soil physical and chemical properties, such as acidification and compaction, as well as restricted plant growth, resulting in stunted plants, reduced quality, and lower yields. This is because long-term continuous cropping leads to uneven consumption of soil nutrients, an imbalance in the proportions of macroelements such as nitrogen, phosphorus, and potassium, and damage to soil structure, reduced porosity, and decreased water and fertilizer retention capacity. Furthermore, continuous cropping can cause soil acidification, lowering the pH value and affecting the activity of enzymes and the availability of nutrients in the soil. Under continuous cropping conditions, the soil microbial ecosystem is disrupted, with a decrease in the number of beneficial microorganisms and a proliferation of harmful microorganisms, especially the accumulation of soil-borne pathogens, which exacerbates the occurrence of root diseases.

[0003] Existing technology CN109370604B describes a soil conditioner for chili pepper cultivation and its preparation method. The soil conditioner uses pine bark, attapulgite, EM (Effective Microorganisms) bacteria, and fermented rice husks as main raw materials, prepared through a multi-step fermentation process. However, in practical applications, it has been found that while the alkaloids from tobacco inhibit bacterial growth, alkaloid residues suppress root respiration in chili peppers and have a broad-spectrum killing effect on soil microbial communities, leading to a reduction in beneficial bacteria such as actinomycetes. Furthermore, although EM bacteria decompose autotoxic substances, the phenolic acids (such as ferulic acid) produced by pine bark decomposition bind at a low rate to the degradation enzymes of EM bacteria, resulting in a still high concentration of autotoxic substances in continuously cropped soils. Therefore, a new soil conditioner for chili pepper cultivation is urgently needed. Summary of the Invention

[0004] The present invention aims to provide a soil conditioner for chili cultivation and its preparation method, which introduces the composite application of nanomaterials and biological macromolecules into the soil conditioner and solves problems such as aggregation and toxicity.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A soil conditioner for chili pepper cultivation comprises, by weight: 6-8 parts of continuously cropped soil, 1.5-2.5 parts of attapulgite soil, 0.5-1.5 parts of bentonite, 0.2-0.5 parts of nano zinc oxide, 1-2 parts of chitosan oligosaccharide, 0.8-1.2 parts of EM microbial agent, and 0.1-0.3 parts of graphene oxide.

[0007] In some embodiments, the EC value of the modifier is controlled within the range of 250–630 μs / cm, and the pH value is controlled within the range of 6.5–7.5.

[0008] In some embodiments, the nano zinc oxide has a particle size of 50-100 nm and its surface is grafted with chitosan oligosaccharide, the chitosan oligosaccharide having a molecular weight of 1000-3000 Da, and forming a composite antibacterial network with graphene oxide through stacking.

[0009] In other embodiments, the attapulgite has a particle size of 150–300 mesh, and the bentonite has a particle size of 100–250 mesh.

[0010] In some embodiments, the EM agent contains 20-30% *Bacillus stearothermophilus* and additionally adds *Bacillus amyloliquefaciens* with a viable count ≥ 2 × 10⁻⁶. 8 CFU / g forms a complex microbial community.

[0011] In some embodiments, the material further includes 0.1 to 0.3 parts of a mesoporous silicon-based material with a pore size distribution of 2 to 50 nm and a specific surface area ≥ 600 m². 2 / g.

[0012] In some embodiments, the material further includes 0.1 to 0.3 parts of a mesoporous silicon-based material with a pore size distribution of 2 to 50 nm and a specific surface area ≥ 600 m². 2 / g.

[0013] A method for preparing a modifier, comprising:

[0014] S1. Disperse 0.2-0.5 parts of nano zinc oxide and 1-2 parts of chitosan oligosaccharide in an ethanol-water mixture (ethanol:water volume ratio 1:1, the amount of which is 5-8 times the total weight of nano zinc oxide and chitosan oligosaccharide) using ultrasonication to obtain a composite aqueous solution; S2. Mix 0.5-1.5 parts of bentonite with half the volume of the composite aqueous solution, stir magnetically, centrifuge, dry, and then sieve to obtain intercalated bentonite;

[0015] S3. Mix 6-8 parts of continuous cropping soil, 1.5-2.5 parts of attapulgite, intercalated bentonite, and 0.1-0.3 parts of mesoporous silica-based material (50% of the total amount) and ball mill them. At the same time, add 0.8-1% of citric acid grinding aid by weight of the mixed matrix. After treatment, sieve. S4. Add 0.1-0.3 parts of graphene oxide to the remaining 1 / 2 volume of the composite aqueous solution and continue stirring for 2 hours to form a composite sol. S5. Spray the composite sol onto the ball-milled matrix and ultrasonically treat it. S6. Mix 0.8-1.2 parts of EM agent with Bacillus amyloliquefaciens suspension and the remaining 50% volume of mesoporous silica-based material. After low-temperature plasma treatment, stir with the above matrix until the water content is 28-30%. Finally, freeze-dry with microwave assistance to obtain the modifier.

[0016] Working principle and beneficial effects of the present invention:

[0017] Bentonite possesses a layered structure. Through intercalation treatment with a composite aqueous solution containing nano-zinc oxide and chitosan oligosaccharide complexes, the nanocomposite can be embedded into the interlayer spaces, significantly expanding the interlayer spacing of the bentonite. This provides attachment sites for other functional components, enhancing its specific surface area and ion exchange capacity. The intercalated bentonite can dynamically regulate the soil's EC value through adsorption and release mechanisms; when the EC value is too high, it releases interlayer K+. + , Ca 2+ When the concentration of buffer salt ions is too low, NH4+ adsorption occurs. + PO4 3- To improve nutrient utilization, it co-adsorbs excess salt ions with attapulgite soil, stabilizing the EC value at 250–630 μS / cm. Simultaneously, it provides a stable loading platform for nano-antibacterial components, enhancing their binding force with the soil.

[0018] Secondly, chitosan oligosaccharides are grafted onto the surface of nano-zinc oxide, forming a complex through covalent bonds between hydroxyl and amino groups. The high specific surface area of ​​nano-zinc oxide disrupts the cell membrane of pathogenic bacteria, while chitosan oligosaccharides inhibit the activity of fungal chitin synthase. The two-dimensional sheet structure of graphene oxide forms a complex network with chitosan oligosaccharides through π-π stacking. Its surface carboxyl groups (-COOH) are covalently linked to the nano-zinc oxide-chitosan oligosaccharide complex, constructing a three-dimensional antibacterial network. Nano-zinc oxide and chitosan oligosaccharides are responsible for efficient antibacterial activity, while graphene oxide enhances the antibacterial durability through physical adsorption and charge interaction.

[0019] Mesoporous silicon-based materials are porous materials primarily composed of silicon dioxide (SiO2), possessing a regular and ordered mesoporous structure (pore size distribution of 2–50 nm) and a specific surface area ≥600 m². 2 / g, pore volume ≥0.8cm 3 / g. Its framework is formed by silicon-oxygen tetrahedra (SiO4) connected by oxygen bridges, and its surface is rich in hydroxyl groups (-OH), which have good hydrophilicity and chemical modification potential.

[0020] Mesoporous silica-based materials, due to their high specific surface area and porous structure, form complexes when mixed with microorganisms. On the one hand, the pores provide colonization space and an anaerobic microenvironment for microorganisms, promoting their metabolic activity; on the other hand, the hydroxyl groups on the material surface bind to the microbial cell walls through hydrogen bonds, enhancing their adsorption stability in the soil and increasing the survival rate of viable bacteria.

[0021] In the preparation method, half of the composite aqueous solution is used for intercalation of bentonite, and half is used for graphene composite sol. The stepwise use of the composite aqueous solution can avoid excessive aggregation of the nano zinc oxide-chitosan oligosaccharide complex in a single stage. The first half is fixed between the bentonite layers through intercalation to form the "skeleton" of the three-dimensional antibacterial network. The latter half forms a two-dimensional composite sol with graphene oxide through π-π stacking, which covers the mineral surface and constructs a dual antibacterial interface.

[0022] This improves the dispersion of the nanocomposite, maximizes the exposure area of ​​the antibacterial components, and the two-dimensional sheets of graphene oxide enhance the mechanical strength of the antibacterial network, preventing the nanoparticles from being lost in the soil.

[0023] One half of the mesoporous silica-based material is ball-milled and mixed with mineral matrices such as continuously cropped soil, attapulgite, and intercalated bentonite. The high specific surface area and porous structure of the mesoporous silica-based material fill the gaps between mineral particles, forming a composite framework. This framework can increase the total porosity of the soil, significantly improve the compaction problem of continuously cropped soil, and enhance aeration and water retention. The pore structure of the other half of the mesoporous silica-based material provides a nanoscale protective microenvironment for EM inoculants and Bacillus amyloliquefaciens. The two halves of the mesoporous material complement each other through different pathways: the mineral mixture provides a stable soil microenvironment for microbial colonization, while the microbial mixture further improves the chemical properties of the mineral framework through metabolic activities. Detailed Implementation

[0024] The following detailed description illustrates the specific implementation method:

[0025] Example 1: A soil conditioner for chili pepper cultivation, comprising, by weight: 6 parts of continuously cropped soil, 1.5 parts of attapulgite soil, 0.5 parts of bentonite, 0.2 parts of nano-zinc oxide, 1 part of chitosan oligosaccharide, 0.8 parts of EM microbial agent, and 0.1 parts of graphene oxide, and also including 0.1 parts of mesoporous silica-based material with a pore size distribution of 2 nm and a specific surface area ≥600 m². 2 / g. The nano zinc oxide has a particle size of 50nm and is grafted with chitosan oligosaccharides, with a molecular weight of 1000Da; the attapulgite has a particle size of 150 mesh, and the bentonite has a particle size of 100 mesh. The EM bacterial agent contains 20% *Bacillus stearothermophilus*, with additional *Bacillus amyloliquefaciens* added.

[0026] A method for preparing a modifier, comprising:

[0027] S1. Nano zinc oxide and chitosan oligosaccharide are ultrasonically dispersed in an ethanol-water mixture with a volume ratio of 1:1 and an amount of 5 times the total weight of nano zinc oxide and chitosan oligosaccharide to obtain a composite aqueous solution; S2. Bentonite is mixed with 1 / 2 of the composite aqueous solution, magnetically stirred, centrifuged, dried, and then sieved to obtain intercalated bentonite.

[0028] S3. Mix 50% of the continuous cropping soil, attapulgite soil, intercalated bentonite, and mesoporous silica-based material, and then ball mill them. At the same time, add citric acid grinding aid according to the weight of the mixed matrix, and then sieve after treatment. S4. Add the remaining 1 / 2 volume of the composite aqueous solution to graphene oxide and continue stirring for 2 hours to form a composite sol. S5. Spray the composite sol onto the ball-milled matrix and ultrasonically treat it. S6. Mix EM agent and Bacillus amyloliquefaciens suspension with the remaining 50% volume of mesoporous silica-based material, treat with low-temperature plasma, stir with the above matrix until the water content is 28%, and finally freeze-dry with microwave assistance to obtain the modifier.

[0029] Example 2 differs from Example 1 in that it includes a soil conditioner for chili pepper cultivation, comprising, by weight: 7 parts of continuously cropped soil, 2 parts of attapulgite soil, 1 part of bentonite, 0.4 parts of nano-zinc oxide, 1.5 parts of chitosan oligosaccharide, 1 part of EM inoculant, and 0.2 parts of graphene oxide, as well as 0.2 parts of mesoporous silica-based material with a pore size distribution of 25 nm and a specific surface area ≥600 m². 2 / g. Among them, the nano zinc oxide has a particle size of 75nm and is grafted with chitosan oligosaccharide on the surface, and the molecular weight of chitosan oligosaccharide is 1500Da; the attapulgite has a particle size of 200 mesh, and the bentonite has a particle size of 200 mesh.

[0030] Example 3 differs from Example 1 in that it includes a soil conditioner for chili pepper cultivation, comprising, by weight: 8 parts of continuously cropped soil, 2.5 parts of attapulgite, 1.5 parts of bentonite, 0.5 parts of nano-zinc oxide, 2 parts of chitosan oligosaccharide, 1.2 parts of EM microbial agent, and 0.3 parts of graphene oxide, as well as 0.3 parts of mesoporous silica-based material with a pore size distribution of 50 nm and a specific surface area ≥600 m². 2 / g. Among them, the nano zinc oxide has a particle size of 100nm and is grafted with chitosan oligosaccharide on the surface, and the molecular weight of chitosan oligosaccharide is 3000Da; the attapulgite has a particle size of 300 mesh, and the bentonite has a particle size of 250 mesh.

[0031] Control group: No soil amendments were applied, and the soil (pH 6.2, EC 820μS / cm, organic matter 18.6g / kg) was in a natural continuous cropping state for 5 years of continuous chili pepper cultivation.

[0032] Existing technology group: Refer to the formula of patent CN109370604B: 32 parts pine bark + 85 parts attapulgite + 1.0 part EM bacteria + 35 parts fermented rice husks. The preparation process is described in the patent specification.

[0033] Control group 1: Compared with Example 1, S2, bentonite was mixed with all the composite aqueous solution, magnetically stirred, centrifuged and dried, and then sieved to obtain intercalated bentonite; S4, pure water was added to graphene oxide and stirred for 2 hours to form a composite sol.

[0034] Control group 2: Compared with Example 1, S2, bentonite was mixed with pure water, magnetically stirred, centrifuged and dried, and then sieved to obtain intercalated bentonite; S4, all composite aqueous solutions were added to graphene oxide and stirred for 2 hours to form a composite sol.

[0035] Control group 3: Compared with Example 1, S3, the continuous cropping soil, attapulgite soil, intercalated bentonite, and all mesoporous silica-based materials were mixed and ball-milled; S3, EM inoculant was mixed with Bacillus amyloliquefaciens suspension.

[0036] Control group 4: Compared with Example 1, S3, continuously cropped soil, attapulgite soil and intercalated bentonite were mixed and ball-milled; S3, EM agent was mixed with Bacillus amyloliquefaciens suspension and all mesoporous silica-based materials.

[0037] Soil samples were collected from chili pepper fields in Zunyi after five years of continuous cropping. The samples were sieved through a 2mm sieve. Initial parameters were: pH 6.2±0.05, EC 820±35μS / cm, organic matter 18.6±1.2g / kg, and Fusarium count 2.1×10⁻⁶. 4 CFU / g soil. Divided into 9 plots (30m). 2 / area), randomized block design, repeated 3 times. Application method: The amendment was spread at 2000 kg / ha, plowed to 20 cm, and "Zunla No. 2" was planted with a plant spacing of 30 cm × 55 cm. Conventional water and fertilizer management was carried out. 60 days after planting, the following indicators were tested: (1) Soil physicochemical properties, pH (glass electrode method), EC (conductivity meter), and aeration porosity (ring cutter method); (2) Microorganisms: Fusarium (selective culture medium counting), EM viable count (dilution coating method); (3) Pepper growth: plant height, stem diameter, taproot length, etc. The following data were obtained:

[0038]

[0039]

[0040] The following conclusions can be drawn from the analysis of the table above:

[0041] (1) Compared with Example 1, Control Group 1 (full intercalation) showed a 110% higher number of Fusarium and an 11.1% higher EC value, demonstrating that the two-dimensional sol formed by the composite aqueous solution after being split in half with graphene can supplement the three-dimensional antibacterial network, improve the antibacterial efficiency by 40%, and optimize EC regulation through graphene ion adsorption. Compared with Example 1, Control Group 2 showed a 3.0% decrease in pH stability and a 25.3% decrease in aeration porosity, indicating that intercalated bentonite is irreplaceable for soil structure improvement. (2) Compared with Example 1, Control Group 3 showed a 32.9% lower number of viable EM bacteria, demonstrating that after splitting the mesoporous silica, 50% of it combines with microorganisms to protect viable bacteria through pores and promote root auxin secretion. Compared with Example 1, Control Group 4 showed a 13.9% lower aeration porosity and a 6.2% higher EC value, indicating that after splitting the mesoporous silica, 50% of it mixes with minerals, which is indispensable for soil pore construction, and the splitting balances structural improvement and biological protection.

[0042] Data from control groups 1-4 indicate that using the full amount of the core material leads to an incomplete antibacterial network or low microbial activity, while using it in half results in a performance breakthrough.

[0043] (3) As the particle size of nano zinc oxide and the pore size of mesoporous silica increase, the inhibition rate of Fusarium increases from 81.4% to 81.9%, and the activity of EM bacteria increases by 12.2%, indicating that the matching between the component scale and the mesoporous structure can further optimize the synergistic effect, but the split design is still the basis of performance.

[0044] (4) Compared with the prior art, Example 1 showed that the Fusarium inhibition rate was increased by 60.8%, the aeration porosity was increased by 43.0%, and the chili plant height was increased by 31.5%.

[0045] In summary, the application of nanomaterials and biomacromolecules in soil conditioners has solved problems such as soil aggregation and weak antibacterial ability.

Claims

1. A soil conditioner for chili pepper cultivation, characterized in that, By weight, it includes: 6-8 parts of continuous cropping soil, 1.5-2.5 parts of attapulgite soil, 0.5-1.5 parts of bentonite, 0.2-0.5 parts of nano zinc oxide, 1-2 parts of chitosan oligosaccharide, 0.8-1.2 parts of EM microbial agent, and 0.1-0.3 parts of graphene oxide.

2. The soil conditioner for chili cultivation according to claim 1, characterized in that, The EC value of the improver is controlled within the range of 250–630 μs / cm, and the pH value is controlled within the range of 6.5–7.

5.

3. The soil conditioner for chili cultivation according to claim 2, characterized in that, The nano zinc oxide has a particle size of 50-100 nm and its surface is grafted with chitosan oligosaccharide. The chitosan oligosaccharide has a molecular weight of 1000-3000 Da and forms a composite antibacterial network with graphene oxide through stacking.

4. The soil conditioner for chili cultivation according to claim 3, characterized in that, The particle size of the attapulgite is 150-300 mesh, and the particle size of the bentonite is 100-250 mesh.

5. The soil conditioner for chili cultivation according to claim 3, characterized in that, The EM bacterial agent contains 20-30% *Bacillus stearothermophilus*, and additionally adds *Bacillus amyloliquefaciens*, with a viable count ≥ 2 × 10⁻⁶. 8 CFU / g forms a complex microbial community.

6. The insecticidal suspension according to claim 5, characterized in that, It also includes 0.1 to 0.3 parts of mesoporous silicon-based materials with a pore size distribution of 2 to 50 nm and a specific surface area ≥ 600 m². 2 / g.

7. A method for preparing the modifier according to any one of claims 1 to 6, characterized in that, include: S1. Disperse 0.2-0.5 parts of nano zinc oxide and 1-2 parts of chitosan oligosaccharide in an ethanol-water mixture with a volume ratio of 1:1 and an amount of 5-8 times the total weight of nano zinc oxide and chitosan oligosaccharide by ultrasonication to obtain a composite aqueous solution. S2. Mix 0.5 to 1.5 parts of bentonite with 1 / 2 volume of composite aqueous solution, stir magnetically, centrifuge and dry, and then sieve to obtain intercalated bentonite; S3. Mix 6-8 parts of continuous cropping soil, 1.5-2.5 parts of attapulgite soil, intercalated bentonite, and 0.1-0.3 parts of mesoporous silica-based material at 50% of their weight and then ball mill them. At the same time, add 0.8-1% of citric acid grinding aid by weight of the mixed matrix and then sieve the mixture. S4. Add 0.1 to 0.3 parts of graphene oxide to the remaining 1 / 2 volume of the composite aqueous solution, and continue stirring for 2 hours to form a composite sol; S5. Spray the composite sol onto the ball-milled matrix and treat it with ultrasound. S6. Mix 0.8-1.2 parts of EM agent with Bacillus amyloliquefaciens suspension and the remaining 50% of mesoporous silica-based material. After low-temperature plasma treatment, stir with the above matrix until the water content is 28-30%. Finally, obtain the modifier by microwave-assisted freeze drying.

8. The application of the soil conditioner according to claims 1 to 6 in regulating soil porosity in continuous cropping of chili peppers, inhibiting Fusarium pathogens, and promoting root growth of chili peppers.

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