Cold-resistant fertilizer for fruits and vegetables and preparation method of cold-resistant fertilizer

Abstract

The invention relates to the technical field of fertilizers, and particularly discloses a cold-resistant fruit and vegetable fertilizer and a preparation method thereof.The cold-resistant fruit and vegetable fertilizer is prepared from, by mass, 55-80 parts of a compound fertilizer, 10-30 parts of a chitosan-based biomass charcoal composite material, 3-5 parts of a microbial composition and 1-3 parts of a plant growth regulator; wherein the biomass charcoal is obtained by carbonizing seaweed, wheat straw and peanut shells as raw materials, the chitosan-based biomass charcoal composite material has a porous structure, has excellent adsorption and slow release effects and good fertilizer and water retention effects, most of the raw materials in the fertilizer are natural organic substances, pollution to soil and the environment is avoided, and under low-temperature stress, the fertilizer has good fertilizer and water retention effects. The fertilizer protects plants through multiple mechanisms, can continuously provide nutrients, guarantees the yield and quality of fruits and vegetables, can adapt to different fruit and vegetable varieties and low-temperature climate conditions in different regions by adjusting the proportion of all the components, and is wide in applicability.

Description

Technical Field

[0001] The present invention relates to the technical field of fertilizers, and specifically to a fertilizer for cold-resistant fruits and vegetables and a preparation method thereof. Background Art

[0002] In recent years, extreme climates have occurred frequently globally, and the frequency of abnormal weather such as low-temperature cold snaps has increased. In agricultural production, low-temperature freezing damage has had a huge impact on the yield and quality of fruits and vegetables, affecting the absorption of crop roots and photosynthesis, causing problems such as flower and fruit dropping, yield reduction, and even plant death, resulting in reduced or even failed harvests of fruits and vegetables, bringing heavy economic losses to growers, and posing a serious threat to the fruit and vegetable planting industry. Enhancing the cold resistance of fruit and vegetable plants through reasonable fertilization is an important and cost-effective means. Traditional chemical fertilizers can supply basic nutrients by providing elements such as nitrogen, phosphorus, and potassium to meet the basic growth needs of fruit and vegetable plants, but the effect of improving the cold resistance performance of fruits and vegetables is poor.

[0003] Chinese Patent Application CN111087259A discloses a liquid fertilizer for cold resistance and stress resistance and promoting plant growth and a preparation method thereof, which includes recycled raw materials, compound amino acids, sulfuric acid solution, potassium hydroxide solution, and microbial bacteria. This fertilizer is safe and non-toxic, can effectively enhance the initial biological resistance of plant seedlings, regulate various physiological functions of plants, and improve cold resistance and stress resistance. However, the components in this fertilizer lack sufficient synergy, the cold resistance mechanism is single, the fertilizer effect is released concentratedly, lacking long-term effectiveness, and it is easy to lose in a low-temperature environment and needs to be supplemented and applied multiple times, greatly increasing the cost. Chinese Patent Application CN109053298A discloses a special fertilizer for improving the cold resistance of fruits and vegetables, which includes, by weight: 60 - 90 parts of fish protein degradation solution, 10 - 20 parts of kelp degradation solution, 10 - 20 parts of calcium nitrate, 10 - 20 parts of molasses fermentation solution, 0.5 - 1 part of penetrant, 0.5 - 1 part of chelating agent, 0.02 - 0.05 part of vitamin B, and 0.02 - 0.05 part of triglyceride. However, the organic fertilizer in this fertilizer decomposes quickly, the fertilizer effect lasts for a short time, the water retention property is poor, and the cold resistance mechanism is single, and the cold resistance effect is average.

[0004] Developing a new type of cold-resistant fertilizer that can effectively enhance the cold resistance of fruits and vegetables, has a long-lasting fertilizer effect, and is environmentally friendly has important practical significance and market demand. Summary of the Invention

[0005] (I) Technical Problems to be Solved Aiming at the deficiencies of the prior art, the present invention provides a fertilizer for cold-resistant fruits and vegetables and a preparation method thereof. The provided fertilizer can effectively enhance the cold resistance of fruits and vegetables and has a long-lasting fertilizer effect.

[0006] (II) Technical Solutions To achieve the above object, the present invention discloses a fertilizer for cold-resistant fruits and vegetables, which comprises the following components by mass: 55-80 parts of compound fertilizer, 10-30 parts of chitosan-based biomass carbon composite material, 3-5 parts of microbial composition, and 1-3 parts of plant growth regulator; The preparation method of the chitosan-based biomass carbon composite material comprises the following steps: S1. Mix biomass powder, surfactant, and deionized water evenly, carry out carbonization treatment in an argon atmosphere. After the treatment is completed, cool, wash with hydrochloric acid solution, filter by suction, wash with deionized water until neutral, and vacuum dry at 60 °C for 12 h to obtain biomass carbon; S2. Mix biomass carbon and mixed acid evenly, disperse ultrasonically, heat up to react. After the reaction is completed, cool to room temperature, filter by suction, wash with deionized water until neutral, and vacuum dry at 60 °C for 12 h to obtain carboxylated biomass carbon; S3. Disperse carboxylated biomass carbon ultrasonically into anhydrous toluene. After uniform dispersion, heat up in a nitrogen atmosphere, add isocyanate ethyl acrylate and catalyst, stir and mix to react. After the reaction is completed, filter by suction, wash with anhydrous toluene, and dry in a drying oven at 60 °C for 12 h to obtain alkenyl-modified biomass carbon; S4. Disperse chitosan ultrasonically into acetic acid solution, adjust the pH to 5-7, stir and mix evenly. In a nitrogen atmosphere, add acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, alkenyl-modified biomass carbon, acrylamide, and initiator, stir and mix, heat up to react. After the reaction is completed, centrifuge, wash with anhydrous ethanol, and dry at 60 °C for 12 h to obtain chitosan-based biomass carbon composite material.

[0007] Preferably, the compound fertilizer is a nitrogen, phosphorus, and potassium compound fertilizer.

[0008] Preferably, the microbial composition is composed of Bacillus subtilis, Bacillus amyloliquefaciens, and Trichoderma harzianum with a mass ratio of 100: (18-30): (25-40).

[0009] Preferably, the plant growth regulator is composed of humic acid and chitosan oligosaccharide with a mass ratio of 100: (30-50).

[0010] Preferably, the biomass powder in S1 is composed of seaweed powder, wheat straw powder, and peanut shell powder with a mass ratio of 4:3:3.

[0011] Preferably, the particle size of the biomass powder in S1 is 60-100 mesh.

[0012] Preferably, the mass ratio of the biomass powder, surfactant, and deionized water in S1 is 100: (120-180): (580-900).

[0013] Preferably, the active agent in S1 is potassium hydroxide.

[0014] Preferably, the carbonization treatment in S1 is carried out in a tubular furnace. During the carbonization treatment, the heating rate is 2 - 5 °C / min, the carbonization temperature is 450 - 520 °C, and the carbonization time is 1 - 2 h.

[0015] Preferably, the concentration of the hydrochloric acid solution in S1 is 2 mol / L.

[0016] Further, the preparation method of the seaweed powder in S1 includes the following steps: washing the seaweed with deionized water. The seaweed is composed of red algae and green algae with a mass ratio of 1:1. After removing surface impurities, it is cut into 3 cm small sections, dried in a drying oven at 60 °C for 12 h, then pulverized and sieved to obtain seaweed powder.

[0017] Further, the preparation method of the wheat straw powder in S1 includes the following steps: washing the wheat straw with deionized water, cutting it into 2 cm small sections, drying in a drying oven at 60 °C for 12 h, performing high-pressure steam sterilization, pulverizing and sieving to obtain wheat straw powder.

[0018] Further, the preparation method of the peanut shell powder in S1 includes the following steps: washing the peanut shells with deionized water, drying in a drying oven at 60 °C for 12 h, pulverizing and sieving to obtain peanut shell powder.

[0019] Preferably, the mass ratio of the biochar to the mixed acid in S2 is 100:(550 - 650).

[0020] Preferably, the mixed acid in S2 is composed of concentrated sulfuric acid and concentrated nitric acid with a mass ratio of 3:1.

[0021] Preferably, the reaction temperature in S2 is 50 - 60 °C, and the reaction time is 3 - 5 h.

[0022] Preferably, the mass ratio of the carboxylated biochar, anhydrous toluene, isocyanatoethyl acrylate and the catalyst in S3 is 100:(5500 - 6500):(180 - 200):(1 - 2).

[0023] Preferably, the catalyst in S3 is dibutyltin dilaurate.

[0024] Preferably, the reaction temperature in S3 is 55 - 65 °C, and the reaction time is 6 - 10 h.

[0025] Preferably, in step S4, the mass ratio of chitosan, acetic acid solution, acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, alkenyl-modified biomass carbon, acrylamide, and initiator is (40-55):(500-800):100:(32-45):(6-10):(25-40):(70-90):(1-3).

[0026] Preferably, in step S4, the reaction temperature is 60-70°C and the reaction time is 3-4 h.

[0027] Preferably, the acetic acid solution in step S4 is an aqueous acetic acid solution with a mass fraction of 1%-3%.

[0028] Preferably, the initiator in step S4 is potassium persulfate.

[0029] A preparation method of a cold-resistant fertilizer for fruits and vegetables comprises the following steps: Mix the compound fertilizer and the chitosan-based biomass carbon composite material in a double-shaft mixer at a stirring rate of 50-100 r / min for 5-8 min, then add the microbial composition and the plant growth regulator, spray distilled water, control the water content ≤8%, stir and mix at a stirring rate of 150-200 r / min for 10-15 min. After mixing evenly, granulate with a granulator, control the humidity at 18%-25%, the particle size at 3-5 mm, dry at 40°C until the water content ≤5%, and sieve to obtain the cold-resistant fertilizer for fruits and vegetables.

[0030] (III) Beneficial technical effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In the present invention, seaweed, wheat straw, and peanut shells are used as raw materials to make biomass powder, which is then carbonized to obtain biomass charcoal, achieving resource recycling. Seaweed contains natural stress-resistant components such as algal polysaccharides and betaine, which can enhance the cold and drought resistance of plants. Wheat straw is rich in cellulose and hemicellulose, and after carbonization, it forms a porous structure, increasing the specific surface area and adsorption capacity of biomass charcoal. Peanut shells contain a relatively high amount of lignin, and after carbonization, they form a stable carbon skeleton, enhancing the mechanical strength and chemical stability of biomass charcoal. The composite components of the three raw materials endow biomass charcoal with both adsorption properties, stress-resistant activity, and structural stability, making it more suitable as a fertilizer carrier. Under the acidification of a mixed acid, carboxyl groups are introduced onto the surface of biomass charcoal to obtain carboxylated biomass charcoal. The carboxyl groups on the carboxylated biomass charcoal react with the isocyanate groups on ethyl isocyanate acrylate under the action of a catalyst to introduce alkenyl groups and amide bonds onto the biomass charcoal, obtaining alkenyl-modified biomass charcoal, effectively avoiding the agglomeration of biomass charcoal, improving the soil aggregate structure, enhancing the soil thermal conductivity, buffering drastic temperature changes, and improving the interfacial compatibility. Chitosan, acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, alkenyl-modified biomass charcoal, and acrylamide polymerize and crosslink under the action of an initiator to obtain a chitosan-based biomass charcoal composite material. 2-Hydroxyethyl methacrylate provides a hydrophilic chain segment, and polyethylene glycol diacrylate enhances the crosslinking density, introducing a large number of active groups to form a stable three-dimensional network gel structure, having excellent mechanical strength and anti-swelling properties, locking in moisture and nutrients, delaying the nutrient release rate, achieving long-term fertilizer supply, and being able to further fix nutrients and enhance cold resistance stability.

[0031] (2) In the present invention, biochar can improve the water adsorption capacity of fertilizers, enhance the water retention performance, alleviate the damage to roots caused by soil water freezing at low temperatures, and can also increase soil organic matter, improve the soil aggregate structure, and enhance the water and fertilizer retention capacity of the soil at low temperatures. Chitosan can induce plants to produce antifreeze proteins, enhance the stability of cell membranes, and at the same time, it has antibacterial effects and reduces the occurrence of diseases at low temperatures. The carboxyl groups in the chitosan-based biochar composite can adsorb metal ions such as K⁺ and Ca²⁺ in the soil, reduce nutrient loss, and improve the slow-release efficiency of fertilizers. The chitosan-based biochar composite forms a slow-release channel, which can effectively load compound fertilizers, microbial compositions, etc. in fertilizers, realize the slow release of nutrients and beneficial bacteria, and maintain continuous supply especially at low temperatures. Further, the chitosan-based biochar composite contains a large number of active groups, which can combine with plant growth regulators through hydrogen bonds to form a slow-release carrier, extend the action time of active substances, and synergistically enhance the cold resistance ability. The chitosan-based biochar composite has a porous structure, has excellent adsorption and slow-release effects, has good fertilizer and water retention effects, can improve the air permeability of the soil, reduce nutrient loss at low temperatures, meet the nutrient requirements of fruits and vegetables at different growth stages, improve the utilization rate of nutrients in fertilizers, and make the fertilizer effect more lasting.

[0032] (3) The nitrogen, phosphorus, and potassium compound fertilizer in the present invention provides the major elements required for the growth of fruits and vegetable plants, provides basic nutritional support, meets the nutritional requirements at different growth stages, can balance plant metabolism, enhance the cell sap concentration, lower the freezing point, and indirectly enhance the cold resistance ability. The nitrogen element contained therein is the main component of proteins in plants. Sufficient nitrogen can promote the robust growth of the roots and leaves of fruits and vegetables and enhance the overall resistance of the plants. The phosphorus element can enhance the root activity of fruits and vegetables and improve the nutrient absorption ability, and can maintain basic metabolism even at low temperatures. The potassium element can help fruits and vegetables accumulate soluble sugars and proline, lower the cell freezing point, and prevent cells from freezing and bursting. Humic acid in the plant growth regulator can improve the soil structure, increase soil fertility, promote the activities of soil microorganisms, and is beneficial to the absorption of nutrients by plants. Further, humic acid has strong adsorption and fertilizer retention properties, can adsorb the nutrients in fertilizers on the surface of soil particles, and release them slowly, providing a long-term and stable nutrient supply for fruits and vegetable plants. Chitosan oligosaccharide can induce plants to produce antifreeze proteins and antioxidant enzymes, and scavenge reactive oxygen species generated by low-temperature stress. In the microbial composition, Bacillus subtilis and Bacillus amyloliquefaciens secrete osmotic adjustment substances such as proline and betaine to lower the cell freezing point, and produce extracellular polysaccharides to wrap the roots to form a protective layer. Trichoderma harzianum activates the expression of cold resistance-related genes in fruits and vegetables by inducing systemic resistance. Further, the microbial composition can decompose soil organic matter to release small molecule carbon sources, promote root development, inhibit the reproduction of pathogenic bacteria, and reduce root rot under low-temperature and high-humidity conditions.

[0033] (4) Most of the raw materials in the fertilizer of the present invention are natural organic substances, which can be decomposed and utilized by microorganisms in the soil and will not cause pollution to the soil and the environment. At the same time, by improving the utilization rate of the fertilizer, nutrient loss is reduced, and the pollution risks to water bodies and the atmosphere are lowered. Under low-temperature stress, the plants are protected through multiple mechanisms, and nutrients can be continuously provided to ensure the yield and quality of fruits and vegetables. Moreover, by adjusting the proportion of each component, it can adapt to different fruit and vegetable varieties and the low-temperature climate conditions in different regions, with wide applicability. Detailed implementation manners

[0034] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below. Preferred embodiments of the present invention are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive. Embodiment

[0035] A preparation method of a cold-resistant fertilizer for fruits and vegetables includes the following steps: By mass, 55 parts of compound fertilizer and 10 parts of chitosan-based biomass carbon composite material are stirred and mixed in a double-shaft mixer. The compound fertilizer is a nitrogen, phosphorus, and potassium compound fertilizer. The stirring and mixing rate is 50 r / min, and the stirring and mixing time is 8 min. Then, 3 parts of microbial composition and 1 part of plant growth regulator are added. The microbial composition is composed of Bacillus subtilis, Bacillus amyloliquefaciens, and Trichoderma harzianum with a mass ratio of 100:18:25. The plant growth regulator is composed of humic acid and chitosan oligosaccharide with a mass ratio of 100:30. Distilled water is sprayed, and the water content is controlled to be ≤8%. Stir and mix, the stirring and mixing rate is 150 r / min, and the stirring and mixing time is 15 min. After mixing evenly, use a granulator to granulate, control the humidity to be 18%, the particle size to be 3 mm, dry at 40 °C until the water content is ≤5%, and sieve to obtain the cold-resistant fertilizer for fruits and vegetables.

[0036] The preparation method of the chitosan-based biomass carbon composite material includes the following steps: S1. Mix the biomass powder, the active agent potassium hydroxide, and deionized water with a mass ratio of 100:120:580 evenly. The biomass powder is composed of seaweed powder, wheat straw powder, and peanut shell powder with a mass ratio of 4:3:3. The particle size of the biomass powder is 60 mesh. Perform carbonization treatment in an argon atmosphere. The carbonization treatment is carried out in a tube furnace. During the carbonization treatment, the heating rate is 2 °C / min, the carbonization treatment temperature is 450 °C, and the carbonization treatment time is 2 h. After the treatment is completed, cool, wash with hydrochloric acid solution with a concentration of 2 mol / L, filter by suction, wash with deionized water until neutral, and vacuum dry at 60 °C for 12 h to obtain biomass carbon; S2. Mix biomass carbon and mixed acid with a mass ratio of 100:550 evenly. The mixed acid consists of concentrated sulfuric acid and concentrated nitric acid with a mass ratio of 3:1. Perform ultrasonic dispersion, raise the temperature, and carry out a reaction at a reaction temperature of 50 °C for 5 h. After the reaction, cool to room temperature, carry out suction filtration, wash with deionized water until neutral, and dry in vacuum at 60 °C for 12 h to obtain carboxylated biomass carbon; S3. Ultrasonically disperse the carboxylated biomass carbon into anhydrous toluene. After uniform dispersion, under a nitrogen atmosphere, raise the temperature, and add ethyl isocyanate acrylate and catalyst dibutyltin dilaurate. The mass ratio of the added carboxylated biomass carbon, anhydrous toluene, ethyl isocyanate acrylate, and catalyst dibutyltin dilaurate is 100:5500:180:1. Stir and mix, and carry out a reaction at 55 °C for 10 h. After the reaction, carry out suction filtration, wash with anhydrous toluene, and dry in a drying oven at 60 °C for 12 h to obtain alkenyl-modified biomass carbon; S4. Ultrasonically disperse chitosan into an acetic acid solution, adjust the pH to 5, stir and mix evenly. Under a nitrogen atmosphere, add acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, alkenyl-modified biomass carbon, acrylamide, and initiator potassium persulfate and stir and mix. The acetic acid solution is an acetic acid aqueous solution with a mass fraction of 1%. The mass ratio of chitosan, acetic acid solution, acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, alkenyl-modified biomass carbon, acrylamide, and initiator potassium persulfate is 40:500:100:32:6:25:70:1. Raise the temperature and carry out a reaction at 60 °C for 4 h. After the reaction, centrifuge, wash with anhydrous ethanol, and dry at 60 °C for 12 h to obtain a chitosan-based biomass carbon composite material. Example

[0037] A preparation method of a cold-resistant fruit and vegetable fertilizer includes the following steps: By mass, mix 65 parts of compound fertilizer and 18 parts of chitosan-based biomass carbon composite material in a double-shaft mixer. The compound fertilizer is a nitrogen, phosphorus, and potassium compound fertilizer. The mixing rate is 80 r / min and the mixing time is 7 min. Then add 4 parts of microbial composition and 2 parts of plant growth regulator. The microbial composition consists of Bacillus subtilis, Bacillus amyloliquefaciens, and Trichoderma harzianum with a mass ratio of 100:22:30. The plant growth regulator consists of humic acid and chitosan oligosaccharide with a mass ratio of 100:38. Spray distilled water, control the water content ≤ 8%, stir and mix. The mixing rate is 180 r / min and the mixing time is 12 min. After mixing evenly, use a granulator to granulate, control the humidity at 20%, and the particle size at 4 mm. Dry at 40 °C until the water content ≤ 5%, and sieve to obtain the cold-resistant fruit and vegetable fertilizer.

[0038] The preparation method of the chitosan-based biomass carbon composite material comprises the following steps: S1. Mix biomass powder, the activating agent potassium hydroxide, and deionized water with a mass ratio of 100:140:750 evenly. The biomass powder is composed of seaweed powder, wheat straw powder, and peanut shell powder with a mass ratio of 4:3:3, and the particle size of the biomass powder is 80 mesh. Conduct carbonization treatment in an argon atmosphere. The carbonization treatment is carried out in a tube furnace. During the carbonization treatment, the heating rate is 3 °C / min, the carbonization temperature is 480 °C, and the carbonization time is 1.5 h. After the treatment is completed, cool it, wash it with hydrochloric acid solution with a concentration of 2 mol / L, filter it by suction, wash it with deionized water until neutral, and dry it in a vacuum at 60 °C for 12 h to obtain biomass carbon. S2. Mix biomass carbon and mixed acid with a mass ratio of 100:580 evenly. The mixed acid is composed of concentrated sulfuric acid and concentrated nitric acid with a mass ratio of 3:1. Conduct ultrasonic dispersion, heat up, and react. The reaction temperature is 55 °C, and the reaction time is 4 h. After the reaction is completed, cool it to room temperature, filter it by suction, wash it with deionized water until neutral, and dry it in a vacuum at 60 °C for 12 h to obtain carboxylated biomass carbon. S3. Ultrasonically disperse the carboxylated biomass carbon into anhydrous toluene. After uniform dispersion, heat up in a nitrogen atmosphere, and add ethyl isocyanate acrylate and the catalyst dibutyltin dilaurate. The mass ratio of the added carboxylated biomass carbon, anhydrous toluene, ethyl isocyanate acrylate, and the catalyst dibutyltin dilaurate is 100:6000:190:1.5. Stir and mix, and react at 60 °C for 8 h. After the reaction is completed, filter it by suction, wash it with anhydrous toluene, and dry it in a drying oven at 60 °C for 12 h to obtain alkenyl-modified biomass carbon. S4. Ultrasonically disperse chitosan into acetic acid solution, adjust the pH to 6, stir and mix evenly. In a nitrogen atmosphere, add acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, alkenyl-modified biomass carbon, acrylamide, and the initiator potassium persulfate and stir and mix. The acetic acid solution is an acetic acid aqueous solution with a mass fraction of 2%. The mass ratio of chitosan, acetic acid solution, acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, alkenyl-modified biomass carbon, acrylamide, and the initiator potassium persulfate is 45:650:100:38:8:30:78:1.8. Heat up and react at 65 °C for 3.5 h. After the reaction is completed, centrifuge it, wash it with absolute ethanol, and dry it at 60 °C for 12 h to obtain the chitosan-based biomass carbon composite material. Example

[0039] A preparation method of a cold-resistant fruit and vegetable fertilizer comprises the following steps: By mass fraction, 65 parts of compound fertilizer and 18 parts of chitosan-based biomass carbon composite are stirred and mixed in a twin-shaft mixer. The compound fertilizer is a nitrogen, phosphorus, and potassium compound fertilizer. The stirring and mixing rate is 80 r / min, and the stirring and mixing time is 7 min. Then, 4 parts of microbial composition and 2 parts of plant growth regulator are added. The microbial composition is composed of Bacillus subtilis, Bacillus amyloliquefaciens, and Trichoderma harzianum with a mass ratio of 100:22:30. The plant growth regulator is composed of humic acid and chitosan oligosaccharide with a mass ratio of 100:38. Distilled water is sprayed, and the water content is controlled to be ≤8%. Stir and mix, the stirring and mixing rate is 180 r / min, and the stirring and mixing time is 12 min. After mixing evenly, use a granulator to granulate, control the humidity to be 20%, and the particle size to be 4 mm. Dry at 40 °C until the water content is ≤5%, and sieve to obtain a fertilizer for cold-resistant fruits and vegetables.

[0040] The preparation method of the chitosan-based biomass carbon composite includes the following steps: S1. Mix biomass powder, active agent potassium hydroxide, and deionized water with a mass ratio of 100:160:850 evenly. The biomass powder is composed of seaweed powder, wheat straw powder, and peanut shell powder with a mass ratio of 4:3:3. The particle size of the biomass powder is 80 mesh. Perform carbonization treatment in an argon atmosphere. The carbonization treatment is carried out in a tubular furnace. During the carbonization treatment, the heating rate is 3 °C / min, the carbonization treatment temperature is 500 °C, and the carbonization treatment time is 1.5 h. After the treatment is completed, cool, wash with hydrochloric acid solution with a concentration of 2 mol / L, filter by suction, wash with deionized water until neutral, and vacuum dry at 60 °C for 12 h to obtain biomass carbon; S2. Mix biomass carbon and mixed acid with a mass ratio of 100:620 evenly. The mixed acid is composed of concentrated sulfuric acid and concentrated nitric acid with a mass ratio of 3:1. Perform ultrasonic dispersion, heat up, and react. The reaction temperature is 55 °C, and the reaction time is 4 h. After the reaction is completed, cool to room temperature, filter by suction, wash with deionized water until neutral, and vacuum dry at 60 °C for 12 h to obtain carboxylated biomass carbon; S3. Ultrasonically disperse the carboxylated biomass carbon into anhydrous toluene. After dispersing evenly, heat up in a nitrogen atmosphere, and add isocyanate ethyl acrylate and catalyst dibutyltin dilaurate. The mass ratio of the added carboxylated biomass carbon, anhydrous toluene, isocyanate ethyl acrylate, and catalyst dibutyltin dilaurate is 100:6000:195:1.8. Stir and mix, react at 60 °C, and the reaction time is 9 h. After the reaction is completed, filter by suction, wash with anhydrous toluene, and dry in a drying oven at 60 °C for 12 h to obtain alkenyl-modified biomass carbon; S4. Ultrasonically disperse chitosan into an acetic acid solution, adjust the pH to 6, stir and mix evenly. In a nitrogen atmosphere, add acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, vinyl-modified biomass carbon, acrylamide, and initiator potassium persulfate and stir and mix. The acetic acid solution is an acetic acid aqueous solution with a mass fraction of 2%. The mass ratio of chitosan, acetic acid solution, acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, vinyl-modified biomass carbon, acrylamide, and initiator potassium persulfate is 50:750:100:42:9:35:85:2.5. Heat up and react at 65 °C for 3.5 h. After the reaction is completed, centrifuge, wash with absolute ethanol, and dry at 60 °C for 12 h to obtain a chitosan-based biomass carbon composite material. Example

[0041] A preparation method of a cold-resistant fertilizer for fruits and vegetables includes the following steps: By mass, mix 75 parts of compound fertilizer and 25 parts of chitosan-based biomass carbon composite material in a double-shaft mixer and stir and mix. The compound fertilizer is a nitrogen, phosphorus, and potassium compound fertilizer. The stirring and mixing rate is 80 r / min, and the stirring and mixing time is 7 min. Then add 4 parts of microbial composition and 2 parts of plant growth regulator. The microbial composition is composed of Bacillus subtilis, Bacillus amyloliquefaciens, and Trichoderma harzianum with a mass ratio of 100:26:35. The plant growth regulator is composed of humic acid and chitosan oligosaccharide with a mass ratio of 100:45. Spray distilled water, control the water content ≤ 8%, stir and mix. The stirring and mixing rate is 180 r / min, and the stirring and mixing time is 12 min. After mixing evenly, use a granulator to granulate, control the humidity to 20%, and the particle size to 4 mm. Dry at 40 °C until the water content ≤ 5%, and sieve to obtain a cold-resistant fertilizer for fruits and vegetables.

[0042] The preparation method of the chitosan-based biomass carbon composite material is the same as that of the chitosan-based biomass carbon composite material in Example 3. Example

[0043] A preparation method of a cold-resistant fertilizer for fruits and vegetables includes the following steps: By mass, 80 parts of compound fertilizer and 30 parts of chitosan-based biomass carbon composite are stirred and mixed in a twin-shaft mixer. The compound fertilizer is a nitrogen, phosphorus, and potassium compound fertilizer. The stirring and mixing rate is 100 r / min, and the stirring and mixing time is 5 min. Then, 5 parts of microbial composition and 3 parts of plant growth regulator are added. The microbial composition is composed of Bacillus subtilis, Bacillus amyloliquefaciens, and Trichoderma harzianum with a mass ratio of 100:30:40. The plant growth regulator is composed of humic acid and chitosan oligosaccharide with a mass ratio of 100:50. Distilled water is sprayed, and the water content is controlled to be ≤8%. Stir and mix at a rate of 200 r / min for 10 min. After mixing evenly, use a granulator to granulate, control the humidity to be 25%, and the particle size to be 5 mm. Dry at 40°C until the water content is ≤5%, and screen to obtain the fertilizer for cold-resistant fruits and vegetables.

[0044] The preparation method of the chitosan-based biomass carbon composite includes the following steps: S1. Mix biomass powder, active agent potassium hydroxide, and deionized water with a mass ratio of 100:180:900 evenly. The biomass powder is composed of seaweed powder, wheat straw powder, and peanut shell powder with a mass ratio of 4:3:3. The particle size of the biomass powder is 100 mesh. Carry out carbonization treatment in an argon atmosphere. The carbonization treatment is carried out in a tube furnace. During the carbonization treatment, the heating rate is 5°C / min, the carbonization temperature is 520°C, and the carbonization time is 1 h. After the treatment is completed, cool, wash with hydrochloric acid solution with a concentration of 2 mol / L, carry out suction filtration, wash with deionized water until neutral, and vacuum dry at 60°C for 12 h to obtain biomass carbon. S2. Mix biomass carbon and mixed acid with a mass ratio of 100:650 evenly. The mixed acid is composed of concentrated sulfuric acid and concentrated nitric acid with a mass ratio of 3:1. Carry out ultrasonic dispersion, heat up, and react. The reaction temperature is 60°C, and the reaction time is 3 h. After the reaction is completed, cool to room temperature, carry out suction filtration, wash with deionized water until neutral, and vacuum dry at 60°C for 12 h to obtain carboxylated biomass carbon. S3. Ultrasonically disperse the carboxylated biomass carbon into anhydrous toluene. After dispersing evenly, heat up in a nitrogen atmosphere, and add isocyanate ethyl acrylate and catalyst dibutyltin dilaurate. The mass ratio of the added carboxylated biomass carbon, anhydrous toluene, isocyanate ethyl acrylate, and catalyst dibutyltin dilaurate is 100:6500:200:2. Stir and mix, and react at 65°C for 6 h. After the reaction is completed, carry out suction filtration, wash with anhydrous toluene, and dry in a drying oven at 60°C for 12 h to obtain alkenyl-modified biomass carbon. S4. Ultrasonically disperse chitosan into an acetic acid solution, adjust the pH to 7, stir and mix evenly. In a nitrogen atmosphere, add acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, vinyl-modified biomass carbon, acrylamide, and initiator potassium persulfate and stir and mix. The acetic acid solution is an acetic acid aqueous solution with a mass fraction of 3%. The mass ratio of chitosan, acetic acid solution, acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, vinyl-modified biomass carbon, acrylamide, and initiator potassium persulfate is 55:800:100:45:10:40:90:3. Raise the temperature and react at 70 °C for 3 h. After the reaction, centrifuge, wash with absolute ethanol, and dry at 60 °C for 12 h to obtain a chitosan-based biomass carbon composite material.

[0045] Comparative Example 1 A method for preparing a compound fertilizer, comprising the following steps: By mass, mix 75 parts of compound fertilizer, 3 parts of biomass carbon, and 22 parts of chitosan-based composite gel in a double-shaft mixer. The compound fertilizer is a nitrogen, phosphorus, and potassium compound fertilizer. The mixing rate is 80 r / min, and the mixing time is 7 min. Then add 4 parts of microbial composition and 2 parts of plant growth regulator. The microbial composition consists of Bacillus subtilis, Bacillus amyloliquefaciens, and Trichoderma harzianum with a mass ratio of 100:26:35. The plant growth regulator consists of humic acid and chitosan oligosaccharide with a mass ratio of 100:45. Spray distilled water, control the water content ≤ 8%, stir and mix. The mixing rate is 180 r / min, and the mixing time is 12 min. After mixing evenly, use a granulator to granulate, control the humidity at 20%, the particle size at 4 mm, dry at 40 °C until the water content ≤ 5%, and sieve to obtain the compound fertilizer.

[0046] The preparation method of the biomass carbon therein includes the following steps: Mix biomass powder, active agent potassium hydroxide, and deionized water with a mass ratio of 100:160:850 evenly. The biomass powder consists of seaweed powder, wheat straw powder, and peanut shell powder with a mass ratio of 4:3:3. The particle size of the biomass powder is 80 mesh. Carry out carbonization treatment in an argon atmosphere. The carbonization treatment is carried out in a tube furnace. During the carbonization treatment, the heating rate is 3 °C / min, the carbonization temperature is 500 °C, and the carbonization time is 1.5 h. After the treatment, cool, wash with hydrochloric acid solution with a concentration of 2 mol / L, filter by suction, wash with deionized water until neutral, and vacuum dry at 60 °C for 12 h to obtain biomass carbon.

[0047] The preparation method of the chitosan-based composite gel therein includes the following steps: Chitosan was ultrasonically dispersed in acetic acid solution, the pH was adjusted to 6, and it was stirred and mixed evenly. In a nitrogen atmosphere, acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, acrylamide, and initiator potassium persulfate were added and stirred and mixed. The acetic acid solution was an acetic acid aqueous solution with a mass fraction of 2%. The mass ratio of chitosan, acetic acid solution, acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, acrylamide, and initiator potassium persulfate was 50:750:100:42:9:85:2.5. The temperature was raised, and the reaction occurred at 65 °C for 3.5 h. After the reaction, it was centrifuged, washed with absolute ethanol, and dried at 60 °C for 12 h to obtain chitosan-based composite gel.

[0048] Comparative Example 2 A preparation method of a compound fertilizer comprises the following steps: By mass, 75 parts of compound fertilizer, 4 parts of chitosan, 3 parts of biochar, and 18 parts of composite gel were stirred and mixed in a double-shaft mixer. The compound fertilizer was a nitrogen, phosphorus, and potassium compound fertilizer. The stirring and mixing rate was 80 r / min, and the stirring and mixing time was 7 min. Then 4 parts of microbial composition and 2 parts of plant growth regulator were added. The microbial composition was composed of Bacillus subtilis, Bacillus amyloliquefaciens, and Trichoderma harzianum with a mass ratio of 100:26:35. The plant growth regulator was composed of humic acid and chitosan oligosaccharide with a mass ratio of 100:45. Distilled water was sprayed, and the water content was controlled to be ≤8%. Stirring and mixing were carried out. The stirring and mixing rate was 180 r / min, and the stirring and mixing time was 12 min. After mixing evenly, it was granulated by a granulator. The humidity was controlled to be 20%, the particle size was 4 mm, and it was dried at 40 °C until the water content was ≤5%. After sieving, the compound fertilizer was obtained.

[0049] The preparation method of the biochar comprises the following steps: Biomass powder, active agent potassium hydroxide, and deionized water with a mass ratio of 100:160:850 were mixed evenly. The biomass powder was composed of seaweed powder, wheat straw powder, and peanut shell powder with a mass ratio of 4:3:3. The particle size of the biomass powder was 80 mesh. Carbonization treatment was carried out in an argon atmosphere. The carbonization treatment was carried out in a tube furnace. During the carbonization treatment, the heating rate was 3 °C / min, the carbonization treatment temperature was 500 °C, and the carbonization treatment time was 1.5 h. After the treatment was completed, it was cooled, washed with hydrochloric acid solution with a concentration of 2 mol / L, filtered by suction, washed with deionized water until neutral, and vacuum dried at 60 °C for 12 h to obtain biochar.

[0050] The preparation method of the composite gel comprises the following steps: Deionized water, acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, acrylamide, and potassium persulfate as an initiator were stirred and mixed. The mass ratio of deionized water, acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, acrylamide, and potassium persulfate was 750:100:42:9:85:2.5. The temperature was raised, and the reaction occurred at 65 °C in a nitrogen atmosphere for 3.5 h. After the reaction, centrifugation was carried out, followed by washing with absolute ethanol and drying at 60 °C for 12 h to obtain the composite gel.

[0051] Comparative Example 3 A preparation method of a composite fertilizer includes the following steps: By mass, 75 parts of compound fertilizer and 25 parts of chitosan-based biomass carbon composite were stirred and mixed in a double-shaft mixer. The compound fertilizer was a nitrogen, phosphorus, and potassium compound fertilizer. The stirring and mixing rate was 80 r / min, and the stirring and mixing time was 7 min. Distilled water was sprayed, and the water content was controlled to be ≤8%. Stirring and mixing were carried out again. The stirring and mixing rate was 180 r / min, and the stirring and mixing time was 12 min. After mixing evenly, granulation was carried out using a granulator, controlling the humidity to be 20% and the particle size to be 4 mm, drying at 40 °C until the water content was ≤5%, and sieving to obtain the composite fertilizer.

[0052] The preparation method of the chitosan-based biomass carbon composite was the same as that of the chitosan-based biomass carbon composite in Example 3.

[0053] The preparation method of the seaweed powder in the above examples and comparative examples includes the following steps: The seaweed was washed with deionized water. The seaweed was composed of red seaweed and green seaweed with a mass ratio of 1:1. After removing surface impurities, it was cut into 3 cm small sections, dried in a drying oven at 60 °C for 12 h, then pulverized and sieved to obtain the seaweed powder.

[0054] The preparation method of the wheat straw powder in the above examples and comparative examples includes the following steps: The wheat straw was washed with deionized water, cut into 2 cm small sections, dried in a drying oven at 60 °C for 12 h, subjected to high-pressure steam sterilization, pulverized, and sieved to obtain the wheat straw powder.

[0055] The preparation method of the peanut shell powder in the above examples and comparative examples includes the following steps: The peanut shell was washed with deionized water, dried in a drying oven at 60 °C for 12 h, pulverized, and sieved to obtain the peanut shell powder.

[0056] In the examples and comparative examples of the present invention, the compound fertilizer was purchased from Hubei Xingfa Chemical Group Co., Ltd., where the compound fertilizer N:P2O5:K2O = 15:6:9; the seaweed was purchased from Qingdao Haixinyuan Biotechnology Co., Ltd.; the Bacillus subtilis was purchased from Jinan Qinghai Chemical Co., Ltd., with the effective viable bacteria ≥ 20 billion / g; the Bacillus amyloliquefaciens was purchased from Shandong Jinyu Biotechnology Co., Ltd., with the effective viable bacteria ≥ 2 billion; the Trichoderma harzianum was purchased from Jinan Qinghai Chemical Co., Ltd., with the effective viable bacteria ≥ 10 billion / g; the chitosan was purchased from Sinopharm Chemical Reagent Co., Ltd.; other raw materials and reagents not specified were commercially available.

[0057] The relevant performance tests were carried out on the fertilizers prepared in Examples 1-5 and Comparative Examples 1-3, and the tests were as follows: (1) The tested tomato variety was "Zidali", purchased from Shengdong Seed Co., Ltd. 270 tomato seedlings at the two-leaf and one-heart stage with consistent growth were randomly divided into nine groups. Examples 1-5 and Comparative Examples 1-3 corresponded to sample groups 1-8 respectively, and the blank group corresponded to the control group. Each group had 30 plants. In sample groups 1-8, the fertilizers in Examples 1-5 and Comparative Examples 1-3 were applied, diluted 100 times with water, and 100 mL of the diluted solution was irrigated to each plant every day. The control group was irrigated with 100 mL of water. After continuous fertilization for 3 days, 24 hours after applying the fertilizer, the tomato seedlings were placed in an artificial climate chamber at 4°C for stress for 48 hours, and then transferred to 25°C for recovery for 7 days, and the survival rate was counted; the leaves of the stressed seedlings were cut into 0.5 cm 2 , put into a test tube, added 10 mL of deionized water, evacuated for 5 minutes, and then left standing for 30 minutes to measure the initial conductivity S0. After boiling for 10 minutes to kill the cells and cooling, the final conductivity S1 was measured, and the permeability of the cell membrane was calculated. The permeability of the cell membrane = (S0 / S1) × 100%; the test results were averaged; (2) The tested tomato variety was "Zidali", purchased from Shengdong Seed Co., Ltd. 90 tomato seedlings with consistent growth were randomly divided into nine groups, denoted as sample groups 1-8 and the blank group. The fertilizers in Examples 1-5 and Comparative Examples 1-3 were applied in sample groups 1-8 respectively, and the compound fertilizer used in the examples and comparative examples was applied in the blank group. The fertilizer was used once at the tomato seedling stage (7 days after transplanting), the flowering stage, and the fruit-setting stage. Each fertilization amount was converted to 50 mg / kg (calculated as pure nitrogen) according to the nitrogen content in the fertilizer. The cultivation conditions were 20-28°C, 12 hours of light per day, and the humidity was 60%-70%. The soil was kept moist. The number of mature fruits of each tomato plant was counted. Randomly select 10 mature fruits, weigh them and calculate the average value, and calculate the total yield of each group. The total yield = the number of fruits per plant × the weight per plant × the number of plants in each group. Based on the blank group, the yield increase rate of tomatoes was calculated. The yield increase rate = (the total yield of the sample group - the total yield of the blank group) / the total yield of the blank group × 100%; The above test results are shown in Table 1: Table 1 Test Items Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Blank Group Survival Rate (%) 80.1 85.9 86.7 88.9 82.8 69.3 55.1 56.4 36.4 Cell Permeability (%) 26.3 21.8 20.1 19.3 22.7 38.4 46.3 45.9 61.8 Yield Increase Rate (%) 8.5 10.3 10.9 12.1 10.5 6.7 5.6 6.1 - It can be seen from the test results in Table 1 that the fertilizers corresponding to Examples 1-5 have excellent cold resistance and can effectively improve the yield and survival rate of crops. In Comparative Example 1, biomass charcoal and chitosan-based composite gel were used to replace the chitosan-based biomass charcoal composite material, and the comprehensive performance decreased. The biomass charcoal was prone to agglomeration, the compatibility between raw materials became poor, the survival rate of seedlings decreased after stress, the cell membrane damage was serious, and the cell permeability was high. In Comparative Example 2, chitosan, biomass charcoal, and composite gel were used to replace the chitosan-based biomass charcoal composite material, the survival rate decreased significantly, the cell permeability increased, and the yield increase rate was average. In Comparative Example 3, the microbial composition and plant growth regulator were not added, and the comprehensive performance decreased, indicating that multiple mechanisms played a synergistic effect on improving the comprehensive performance of plants.

[0058] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. All equivalent changes and improvements made within the scope of the present invention application shall still fall within the scope covered by the present invention.

Claims

1. A fertilizer for cold-resistant fruits and vegetables, characterized in that: By mass fraction, it includes the following components: 55 - 80 parts of compound fertilizer, 10 - 30 parts of chitosan-based biomass carbon composite, 3 - 5 parts of microbial composition, and 1 - 3 parts of plant growth regulator; The preparation method of the chitosan-based biomass carbon composite includes the following steps: S1. Mix biomass powder, surfactant, and deionized water evenly, carry out carbonization treatment in an argon atmosphere. After the treatment is completed, cool it, wash it with hydrochloric acid solution, filter it by suction, wash it until neutral, and dry it at 60 °C for 12 h to obtain biomass carbon; S2. Mix biomass carbon and mixed acid evenly, disperse it by ultrasonic wave, raise the temperature to react. After the reaction ends, cool it, filter it by suction, wash it until neutral, and dry it at 60 °C for 12 h to obtain carboxylated biomass carbon; S3. Ultrasonically disperse the carboxylated biomass carbon into anhydrous toluene. After uniform dispersion, in a nitrogen atmosphere, raise the temperature, add isocyanate ethyl acrylate and catalyst, stir and mix to react. After the reaction ends, filter it by suction, wash it, and dry it at 60 °C for 12 h to obtain alkenyl-modified biomass carbon; S4. Ultrasonically disperse chitosan into acetic acid solution, adjust the pH to 5 - 7, stir and mix evenly. In a nitrogen atmosphere, add acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, alkenyl-modified biomass carbon, acrylamide, and initiator, stir and mix, raise the temperature to react. After the reaction ends, centrifuge it, wash it, and dry it at 60 °C for 12 h to obtain chitosan-based biomass carbon composite.

2. The cold-resistant fruit and vegetable fertilizer according to claim 1, characterized in that: The compound fertilizer is a nitrogen, phosphorus, and potassium compound fertilizer.

3. The fertilizer for cold-resistant fruits and vegetables according to claim 1, characterized in that: The microbial composition is composed of Bacillus subtilis, Bacillus amyloliquefaciens, and Trichoderma harzianum with a mass ratio of 100:(18 - 30):(25 - 40).

4. The fertilizer for cold-resistant fruits and vegetables according to claim 1, characterized in that: The plant growth regulator is composed of humic acid and chitosan oligosaccharide with a mass ratio of 100:(30 - 50).

5. A fertilizer for cold-resistant fruits and vegetables according to claim 1, characterized in that: In S1, the biomass powder is composed of seaweed powder, wheat straw powder, and peanut shell powder with a mass ratio of 4:3:

3. The particle size of the biomass powder is 60 - 100 mesh, and the mass ratio of the biomass powder, surfactant, and deionized water is 100:(120 - 180):(580 - 900).

6. The fertilizer for cold-resistant fruits and vegetables according to claim 1, characterized in that: In S1, the carbonization treatment is carried out in a tubular furnace. During the carbonization treatment, the heating rate is 2 - 5 °C / min, the carbonization temperature is 450 - 520 °C, and the carbonization time is 1 - 2 h.

7. A fertilizer for cold-resistant fruits and vegetables according to claim 1, characterized in that: In S2, the mass ratio of biomass carbon to mixed acid is 100:(550 - 650). The mixed acid is composed of concentrated sulfuric acid and concentrated nitric acid with a mass ratio of 3:

1. The reaction temperature is 50 - 60 °C, and the reaction time is 3 - 5 h.

8. The fertilizer for cold-resistant fruits and vegetables according to claim 1, characterized in that: In S3, the mass ratio of carboxylated biomass carbon, anhydrous toluene, isocyanate ethyl acrylate, and catalyst is 100:(5500 - 6500):(180 - 200):(1 - 2). The reaction temperature is 55 - 65 °C, and the reaction time is 6 - 10 h.

9. The fertilizer for cold-resistant fruits and vegetables according to claim 1, characterized in that: In S4, the mass ratio of chitosan, acetic acid solution, acrylic acid, 2-hydroxyethyl methacrylate, polyethylene glycol diacrylate, alkenyl-modified biomass carbon, acrylamide, and initiator is (40 - 55):(500 - 800):100:(32 - 45):(6 - 10):(25 - 40):(70 - 90):(1 - 3), the reaction temperature is 60 - 70 °C, and the reaction time is 3 - 4 h.

10. A method for preparing a cold-resistant fertilizer for fruits and vegetables according to any one of claims 1-9, characterized in that: It includes the following steps: Stir and mix the compound fertilizer and the chitosan-based biomass carbon composite at a stirring and mixing rate of 50 - 100 r / min for 5 - 8 min, then add the microbial composition and the plant growth regulator, spray distilled water, control the water content ≤ 8%, stir and mix at a stirring and mixing rate of 150 - 200 r / min for 10 - 15 min. After mixing evenly, granulate, control the humidity at 18% - 25%, with a particle size of 3 - 5 mm, dry at 40 °C until the water content ≤ 5%, and sieve to obtain the fertilizer for cold-resistant fruits and vegetables.