Agricultural biological wetting agent for cultivation substrate, preparation method and application thereof

Abstract

The invention discloses an agricultural biowetting agent for a cultivation substrate, a preparation method thereof, and an application thereof. The invention comprises the following steps: polyethylene glycol is blended with traditional Chinese medicine residue powder, the polyethylene glycol is attached to the surface of the traditional Chinese medicine residue powder, the polyethylene glycol is thermally decomposed during a pyrolysis and carbonization treatment process, and an uneven structure is formed on the surface of biochar, thereby increasing the specific surface area of ​​the biochar and improving the water absorption performance of the biochar; humic acid and a cross-linking agent are then adsorbed by utilizing the adsorption effect of the porous biochar, the humic acid is cross-linked between the porous structures of the biochar to form a gel structure, and the humic acid has excellent water absorption capacity, thereby improving the water absorption and swelling performance of the biochar; the modified biochar is then added to a konjac gum solution, the konjac gum is fixed on the surface of the modified biochar due to hydrogen bonding between interfaces, and after freeze-drying, a gel layer is formed on the surface of the modified biochar, thereby further improving the water absorption and swelling performance of the biochar.

Description

Technical Field

[0001] The invention relates to the technical field of cultivation substrates, and in particular to an agricultural biological wetting agent for cultivation substrates, a preparation method and application thereof. Background Art

[0002] Soilless culture has been rapidly developed and promoted since the 1930s and is now widely used in horticulture, plant container cultivation, agricultural production and other fields.

[0003] Substrate cultivation is the most widely used method of soilless cultivation. It involves anchoring crop roots in an organic or inorganic matrix and providing the necessary nutrients or water through drip irrigation or trickle irrigation. Currently, most countries around the world use gravel, sand, mud (grass), vermiculite, perlite, rock wool, sawdust, and other materials as anchoring substrates. With the widespread application of soilless cultivation technology, the demand for substrates is increasing, leading to the emergence of specialized substrate production companies. The variety of substrates is also increasing, showing a trend of segmentation and specialization.

[0004] The most important factors affecting the quality of cultivation substrates include the physical, chemical and biological properties of the substrate. The physical properties of the substrate that have a greater impact on cultivated crops mainly include bulk density, total porosity, particle size, etc.; the chemical properties mainly include chemical composition (including organic nutrients and mineral nutrients), pH, electrical conductivity, etc.; the biological properties mainly refer to the stability of organic matter in the substrate.

[0005] When preparing a cultivation matrix, the total porosity and water holding capacity of the matrix are two important reference factors. Therefore, a water-retaining agent is usually added to the cultivation matrix. Chinese patent document CN201510495434.8 discloses a method for preparing a rice husk charcoal-based water-retaining agent. The method comprises diluting an acrylic acid monomer with deionized water to a mass percentage concentration of 50%, carbonizing the rice husk and then crushing it. The mixture is mixed with a water-soluble acrylic acid monomer in a reactor, and then neutralized with an aqueous NaOH solution. An additive, a cross-linking agent, and an initiator are then added in sequence. The additive is acrylamide, the cross-linking agent is N,N'-methylenebisacrylamide, and the initiator is ammonium persulfate. The mixture is polymerized at 70-80°C for 30-45 minutes. The polymer is placed in an oven at 85°C for polymerization reaction for 3 hours, crushed, and passed through a 60-mesh sieve to obtain an off-white rice husk charcoal-based water-retaining agent. However, the water-retaining performance of the water-retaining agent prepared by this patent still needs to be further improved. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide an agricultural biological wetting agent for cultivation substrates, a preparation method and application thereof, and when applied to cultivation substrates, the obtained cultivation substrates have excellent water retention and air permeability.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing an agricultural biological wetting agent for a cultivation substrate comprises the following steps:

[0009] S1, drying, grinding, and sieving the Chinese medicine residue to obtain Chinese medicine residue powder;

[0010] S2, dissolving polyethylene glycol in ethanol solvent, then adding Chinese medicine residue powder thereto, uniformly dispersing by ultrasonication, vacuum drying, and then pyrolysis carbonization treatment, followed by cooling to room temperature, grinding, and sieving to obtain porous biochar;

[0011] S3, immersing the porous biochar in a mixed solution containing humic acid and a cross-linking agent, followed by filtering and drying to obtain modified biochar;

[0012] S4, uniformly mixing the modified biochar and the composite Trichoderma agent to obtain a biochar-loaded microbial agent, wherein the mass ratio of the modified biochar to the composite Trichoderma agent is 40-60:3-5;

[0013] S5. Add konjac gum to deionized water, stir to dissolve, then add biochar-loaded microbial agent, disperse evenly, and freeze-dry to obtain an agricultural biological wetting agent.

[0014] Preferably, in step S1, the Chinese medicine residue is selected from Epimedium residue, Isatis root residue or Houttuynia cordata residue.

[0015] Preferably, in step S1, the particle size of the traditional Chinese medicine residue powder is 0.6-2 mm.

[0016] Preferably, in step S2, the mass ratio of polyethylene glycol to traditional Chinese medicine residue powder is 1-2:10-15.

[0017] Preferably, in step S2, the pyrolysis carbonization treatment temperature is 450-600° C., and the pyrolysis carbonization treatment time is 2-3 hours.

[0018] Preferably, in step S3, the mass fraction of humic acid in the mixed solution is 4-8%, and the mass fraction of the cross-linking agent is 1-2%.

[0019] Preferably, in step S3, the cross-linking agent is selected from polyethylene glycol diglycidyl ether.

[0020] Preferably, in step S3, the mass ratio of the porous biochar to the mixed solution is 10-15:100.

[0021] Preferably, in step S5, the mass ratio of konjac gum to biochar-loaded microbial agent is 3-5:10-20.

[0022] The present invention provides an agricultural biological wetting agent prepared by the above preparation method.

[0023] The present invention also provides application of the agricultural biological wetting agent in a cultivation matrix.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention blends polyethylene glycol with traditional Chinese medicine residue powder, and after vacuum drying, polyethylene glycol adheres to the surface of the traditional Chinese medicine residue powder. During the pyrolysis and carbonization process, the polyethylene glycol is thermally decomposed to form an uneven structure on the surface of the biochar, thereby increasing the specific surface area of ​​the biochar and thereby improving the water absorption performance of the biochar.

[0026] (2) The present invention utilizes the adsorption effect of porous biochar to adsorb humic acid and a cross-linking agent. Subsequently, during the drying process, humic acid is cross-linked between the porous structure of the biochar to form a gel structure. Humic acid has excellent water absorption capacity, thereby improving the water absorption and swelling properties of the biochar. At the same time, humic acid, as a fertilizer, can provide nutrients for plant growth. The modified biochar is then added to the konjac glucomannan solution. Due to the hydrogen bonding effect between the interfaces, the konjac glucomannan is fixed on the surface of the modified biochar. After freeze-drying, a gel layer is formed on the surface of the modified biochar, further improving the water absorption and swelling properties of the biochar. At the same time, the konjac glucomannan gel layer wraps the humic acid inside, and can also achieve the effect of slow release of fertilizer. The wetting agent prepared by the present invention is dispersed in the cultivation matrix, which can effectively maintain the soft and loose structural state of the matrix and maintain the water-retaining and breathable effect of the matrix.

[0027] (3) The composite Trichoderma agent used in the present invention contains highly active Bacillus subtilis, Bacillus licheniformis, Trichoderma harzianum and Trichoderma longibrachiatum, which can prevent and treat a variety of fungal and bacterial diseases, and use the characteristics of microorganisms to accelerate the decomposition of organic matter in the soil, activate soil nutrients, release phosphorus and potassium in the soil, improve the soil fertilizer supply environment, and protect the healthy growth of crops. The specific effects are as follows: 1. Inhibition of soil-borne diseases: This product is a composite microbial agent composed of bacteria and fungi. Through microbial nutrient competition and root occupation, it can not only inhibit fungal soil-borne diseases, but also inhibit bacterial soil-borne diseases, reduce the disease index of continuous crops, and prevent the growth of crops year after year. Application can greatly alleviate the obstacles of continuous cropping; 2. Induce plant resistance: Microbial metabolic products can induce plant immunity, enhance the plant's own ability to resist invasion by pathogens, and also improve the plant's resistance to harsh natural environments; 3. Stimulate plant growth: This product is a solid fermentation product, and its matrix contains rich beneficial ingredients, which can stimulate plant growth and promote the development of plant root systems; 4. Increase crop nutrition: Through microbial activity, the insoluble phosphorus, zinc, calcium, magnesium, etc. in the soil are converted into nutrients that can be used by plants, providing nutrition for plants; 5. Decompose pesticide and harmful organic matter residues in the soil, improve the quality of agricultural products, and reduce the accumulation of nitrates in agricultural products.

[0028] (4) The raw materials of the agricultural biological wetting agent prepared by the present invention are derived from Chinese herbal medicine residues, which have the characteristics of wide sources and low costs, realize the resource utilization of waste, and have obvious social and environmental benefits. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0030] It should be noted that, unless otherwise specified, all chemical reagents involved in the present invention were purchased through commercial channels.

[0031] The polyethylene glycol used in the present invention is PEG-400;

[0032] CAS number of fulvic acid: 479-66-3;

[0033] Konjac gum was purchased from Jiangsu Caiwei Biotechnology Co., Ltd.;

[0034] The composite Trichoderma agent was purchased from Hubei Qiming Bioengineering Co., Ltd., with registration number Microbial Fertilizer (2022) Standard No. (11441) and implementation standard GB20287-2006.

[0035] Example 1

[0036] A method for preparing an agricultural biological wetting agent for a cultivation substrate comprises the following steps:

[0037] S1, drying, grinding, and sieving the Houttuynia cordata residue to obtain a Chinese herbal medicine residue powder with a particle size of 0.6-2 mm;

[0038] S2. Dissolve 1 g of polyethylene glycol in 100 mL of ethanol solvent, then add 10 g of traditional Chinese medicine residue powder, disperse evenly with ultrasound, dry in a vacuum at 50° C., and then perform pyrolysis carbonization treatment at a temperature of 450° C. for 3 h. Then cool to room temperature, grind, and sieve to obtain porous biochar with a particle size of 0.6-2 mm.

[0039] S3, immersing 10 g of porous biochar in 100 g of a mixed solution, wherein the mass fraction of humic acid is 4% and the mass fraction of polyethylene glycol diglycidyl ether is 1%, for 2 h, followed by filtering and drying at 60° C. for 3 h to obtain modified biochar;

[0040] S4, uniformly mixing the modified biochar and the composite Trichoderma agent to obtain a biochar-loaded microbial agent, wherein the mass ratio of the modified biochar to the composite Trichoderma agent is 40:3;

[0041] S5. Add 3 g of konjac gum to 100 g of deionized water, stir to dissolve, then add 10 g of biochar-loaded microbial agent, disperse evenly, and freeze-dry to obtain an agricultural biological wetting agent.

[0042] Example 2

[0043] A method for preparing an agricultural biological wetting agent for a cultivation substrate comprises the following steps:

[0044] S1. Drying, grinding, and sieving the epimedium residue to obtain a Chinese medicinal residue powder with a particle size of 0.6-2 mm;

[0045] S2. Dissolve 2 g of polyethylene glycol in 100 mL of ethanol solvent, then add 15 g of traditional Chinese medicine residue powder, disperse evenly by ultrasonication, dry in a vacuum at 50 ° C, and then perform pyrolysis carbonization treatment at 600 ° C for 2 h. Then cool to room temperature, grind, and sieve to obtain porous biochar with a particle size of 0.6-2 mm.

[0046] S3, immersing 15 g of porous biochar in 100 g of a mixed solution, wherein the mass fraction of humic acid is 8% and the mass fraction of polyethylene glycol diglycidyl ether is 2%, for 2 h, followed by filtering and drying at 60° C. for 3 h to obtain modified biochar;

[0047] S4, uniformly mixing the modified biochar and the composite Trichoderma agent to obtain a biochar-loaded microbial agent, wherein the mass ratio of the modified biochar to the composite Trichoderma agent is 60:5;

[0048] S5. Add 5 g of konjac gum to 100 g of deionized water, stir to dissolve, then add 20 g of biochar-loaded microbial agent, disperse evenly, and freeze-dry to obtain an agricultural biological wetting agent.

[0049] Example 3

[0050] A method for preparing an agricultural biological wetting agent for a cultivation substrate comprises the following steps:

[0051] S1, drying, grinding, and sieving the Radix Isatidis residue to obtain a Chinese medicinal residue powder with a particle size of 0.6-2 mm;

[0052] S2. 1.5 g of polyethylene glycol was dissolved in 100 mL of ethanol solvent, and then 12 g of traditional Chinese medicine residue powder was added thereto, and the mixture was uniformly dispersed by ultrasonication. After vacuum drying at 50° C., the mixture was subjected to pyrolysis and carbonization treatment at a temperature of 500° C. for 2 h. The mixture was then cooled to room temperature, ground, and sieved to obtain porous biochar with a particle size of 0.6-2 mm.

[0053] S3, immersing 12 g of porous biochar in 100 g of a mixed solution, wherein the mass fraction of humic acid is 5% and the mass fraction of polyethylene glycol diglycidyl ether is 2%, for 2 h, followed by filtering and drying at 60° C. for 3 h to obtain modified biochar;

[0054] S4, uniformly mixing the modified biochar and the composite Trichoderma agent to obtain a biochar-loaded microbial agent, wherein the mass ratio of the modified biochar to the composite Trichoderma agent is 50:5;

[0055] S5. Add 4 g of konjac gum to 100 g of deionized water, stir to dissolve, then add 15 g of biochar-loaded microbial agent, disperse evenly, and freeze-dry to obtain an agricultural biological wetting agent.

[0056] Example 4

[0057] A method for preparing an agricultural biological wetting agent for a cultivation substrate comprises the following steps:

[0058] S1. Drying, grinding, and sieving the epimedium residue to obtain a Chinese medicinal residue powder with a particle size of 0.6-2 mm;

[0059] S2. Dissolve 2 g of polyethylene glycol in 100 mL of ethanol solvent, then add 12 g of traditional Chinese medicine residue powder, disperse evenly with ultrasound, dry in a vacuum at 50 ° C, and then perform pyrolysis carbonization treatment at a temperature of 550 ° C for 2 h. Then cool to room temperature, grind, and sieve to obtain porous biochar with a particle size of 0.6-2 mm.

[0060] S3, immersing 15 g of porous biochar in 100 g of a mixed solution, wherein the mass fraction of humic acid is 6% and the mass fraction of polyethylene glycol diglycidyl ether is 1.5%, for 2 h, followed by filtering and drying at 60° C. for 3 h to obtain modified biochar;

[0061] S4, uniformly mixing the modified biochar and the composite Trichoderma agent to obtain a biochar-loaded microbial agent, wherein the mass ratio of the modified biochar to the composite Trichoderma agent is 40:4;

[0062] S5. Add 4 g of konjac gum to 100 g of deionized water, stir to dissolve, then add 18 g of biochar-loaded microbial agent, disperse evenly, and freeze-dry to obtain an agricultural biological wetting agent.

[0063] Comparative Example 1

[0064] A method for preparing an agricultural biological wetting agent for a cultivation substrate comprises the following steps:

[0065] S1, drying, grinding, and sieving the Houttuynia cordata residue to obtain a Chinese herbal medicine residue powder with a particle size of 0.6-2 mm;

[0066] S2, subjecting the traditional Chinese medicine residue powder to pyrolysis carbonization treatment at a temperature of 450° C. for 3 h, followed by cooling to room temperature, grinding, and sieving to obtain porous biochar with a particle size of 0.6-2 mm;

[0067] S3, immersing 10 g of porous biochar in 100 g of a mixed solution, wherein the mass fraction of humic acid is 4% and the mass fraction of polyethylene glycol diglycidyl ether is 1%, for 2 h, followed by filtering and drying at 60° C. for 3 h to obtain modified biochar;

[0068] S4, uniformly mixing the modified biochar and the composite Trichoderma agent to obtain a biochar-loaded microbial agent, wherein the mass ratio of the modified biochar to the composite Trichoderma agent is 40:3;

[0069] S5. Add 3 g of konjac gum to 100 g of deionized water, stir to dissolve, then add 10 g of biochar-loaded microbial agent, disperse evenly, and freeze-dry to obtain an agricultural biological wetting agent.

[0070] Comparative Example 2

[0071] A method for preparing an agricultural biological wetting agent for a cultivation substrate comprises the following steps:

[0072] S1, drying, grinding, and sieving the Houttuynia cordata residue to obtain a Chinese herbal medicine residue powder with a particle size of 0.6-2 mm;

[0073] S2. Dissolve 1 g of polyethylene glycol in 100 mL of ethanol solvent, then add 10 g of traditional Chinese medicine residue powder, disperse evenly with ultrasound, dry in a vacuum at 50° C., and then perform pyrolysis carbonization treatment at a temperature of 450° C. for 3 h. Then cool to room temperature, grind, and sieve to obtain porous biochar with a particle size of 0.6-2 mm.

[0074] S3, immersing 10 g of porous biochar in 100 g of a mixed solution, wherein the mass fraction of humic acid is 4% and the mass fraction of polyethylene glycol diglycidyl ether is 1%, for 2 h, followed by filtering and drying at 60° C. for 3 h to obtain modified biochar;

[0075] S4. Evenly mix the modified biochar and the composite Trichoderma agent to obtain an agricultural biological wetting agent, wherein the mass ratio of the modified biochar to the composite Trichoderma agent is 40:3.

[0076] Comparative Example 3

[0077] A method for preparing an agricultural biological wetting agent for a cultivation substrate comprises the following steps:

[0078] S1, drying, grinding, and sieving the Houttuynia cordata residue to obtain a Chinese herbal medicine residue powder with a particle size of 0.6-2 mm;

[0079] S2. Dissolve 1 g of polyethylene glycol in 100 mL of ethanol solvent, then add 10 g of traditional Chinese medicine residue powder, disperse evenly with ultrasound, dry in a vacuum at 50° C., and then perform pyrolysis carbonization treatment at a temperature of 450° C. for 3 h. Then cool to room temperature, grind, and sieve to obtain porous biochar with a particle size of 0.6-2 mm.

[0080] S3, uniformly mixing the modified biochar and the composite Trichoderma agent to obtain a biochar-loaded microbial agent, wherein the mass ratio of the modified biochar to the composite Trichoderma agent is 40:3;

[0081] S4. Add 3 g of konjac gum to 100 g of deionized water, stir to dissolve, then add 10 g of biochar-loaded microbial agent, disperse evenly, and freeze-dry to obtain an agricultural biological wetting agent.

[0082] The performance tests of the wetting agents prepared in Example 1 and Comparative Examples 1-3 are as follows:

[0083] Cow dung, shiitake mushroom residue, and sauce-flavored liquor lees were piled up in a mass ratio of 6:2:2, naturally fermented at 60°C for 7 days, turned over, piled for another 30 days, naturally air-dried, and then crushed to obtain decomposed sheep dung with a particle size of 1-2 mm; then 80 parts of decomposed sheep dung were evenly mixed with 20 parts of a wetting agent to obtain a cultivation medium;

[0084] Take a 2L beaker and weigh its net weight (m1). Fill the beaker with dried cultivation medium to the 1L mark and weigh it (m2). Then seal the beaker with cultivation medium with two layers of wet gauze and soak it in water for 24 hours (the water level must always be at least 2cm above the top of the container). Take it out of the water and pour out the water above the 1L mark to weigh it in the saturated water state (m3). Also weigh the wet gauze used for sealing (m4). Finally, wrap the beaker with wet gauze and invert it for 8 hours to allow the water (gravity water) in the beaker to drain freely and weigh it (m5).

[0085] Water absorption capacity = (m5-m1-m4) / (m2-m1)×100%;

[0086] Total porosity = (m3-m2) / 1000×100%;

[0087] Ventilation porosity = (m3 + m4 - m5) / 1000 × 100%;

[0088] Water holding porosity = total porosity - air permeability porosity;

[0089] Air-water ratio = air-permeable porosity / water-holding porosity;

[0090] The test results are shown in the following table:

[0091] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Water absorption performance (%) 435.18 273.26 342.47 367.73 Total porosity (%) 78.69 54.32 60.54 69.21 Ventilation porosity (%) 25.26 23.05 22.86 23.85 Water holding porosity (%) 53.43 31.27 37.68 45.36 Gas-water ratio 0.47 0.74 0.61 0.53

[0092] Finally, it should be noted that the above embodiments do not limit the present invention in any form. Those skilled in the art will appreciate that modifications and improvements can be made based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are intended to fall within the scope of protection claimed in the present invention.

Claims

1. A method for preparing an agricultural wetting agent for a cultivation substrate, characterized in that: The steps include: S1, drying, grinding, and sieving the Chinese medicine residue to obtain Chinese medicine residue powder; S2, dissolving polyethylene glycol in ethanol solvent, then adding Chinese medicine residue powder thereto, uniformly dispersing by ultrasonication, vacuum drying, and then pyrolysis carbonization treatment, followed by cooling to room temperature, grinding, and sieving to obtain porous biochar; S3, immersing the porous biochar in a mixed solution containing humic acid and a cross-linking agent, followed by filtering and drying to obtain modified biochar; S4, uniformly mixing the modified biochar and the composite Trichoderma agent to obtain a biochar-loaded microbial agent, wherein the mass ratio of the modified biochar to the composite Trichoderma agent is 40-60:3-5; S5, add konjac gum to deionized water, stir and dissolve, then add biochar-loaded microbial inoculum, disperse evenly, and freeze-dry to obtain an agricultural wetting agent; In step S5, the mass ratio of konjac gum to biochar-loaded microbial agent is 3-5:10-20.

2. The method for preparing an agricultural wetting agent for a cultivation substrate according to claim 1, wherein: In step S1, the particle size of the traditional Chinese medicine residue powder is 0.6-2 mm.

3. The method for preparing an agricultural wetting agent for a cultivation substrate according to claim 1, wherein: In step S2, the mass ratio of polyethylene glycol to traditional Chinese medicine residue powder is 1-2:10-15.

4. The method for preparing an agricultural wetting agent for a cultivation substrate according to claim 1, wherein: In step S2, the pyrolysis carbonization treatment temperature is 450-600° C., and the pyrolysis carbonization treatment time is 2-3 hours.

5. The method for preparing an agricultural wetting agent for a cultivation substrate according to claim 1, wherein: In step S3, the mass fraction of humic acid in the mixed solution is 4-8%, and the mass fraction of the cross-linking agent is 1-2%.

6. The method for preparing an agricultural wetting agent for a cultivation substrate according to claim 1, wherein: In step S3, the cross-linking agent is selected from polyethylene glycol diglycidyl ether.

7. The method for preparing an agricultural wetting agent for a cultivation substrate according to claim 1, wherein: In step S3, the mass ratio of the porous biochar to the mixed solution is 10-15:

100.

8. The agricultural wetting agent prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the agricultural wetting agent as claimed in claim 8 in a cultivation medium.